| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 311.1 | 1 vote for Laser Launch! | SOFBAS::WOLFF | | Tue Jul 14 1987 14:02 | 2 |
| I vote for Laser Launch ala Jerry Pournelle's novels. Such an elegant
idea, and modelling shows that its feasible!
|
| 311.2 | X tons to Orbit | SOFBAS::WOLFF | | Tue Jul 14 1987 14:15 | 3 |
| Maybe the figure of 10 tons is too high. Say, ... any single digit
ton mass figure, from 1 to 10. How to economically get it into
orbit. (Quick, dirty, and safe!)
|
| 311.3 | In the future... | EDEN::KLAES | The Universe is safe. | Tue Jul 14 1987 14:46 | 6 |
| How about the Space Elevator?
Or the transporter?
Larry
|
| 311.4 | | JETSAM::ANDRADE | The sentinel (.)(.) | Tue Jul 14 1987 14:56 | 4 |
| Put an asteroid in Earth orbit.
Then just use it to make anything you want. No need to carry it
all up.
|
| 311.5 | :-) | STAR::BANKS | In Search of Mediocrity | Tue Jul 14 1987 15:17 | 4 |
| Put all the lawyers, politicians and lobbyists you can find on a
very long ladder, and have them "bucket brigade" it up, piece by
piece into orbit. With them occupied like this, maybe the rest
of us can get on with our lives unimpeded.
|
| 311.6 | cheap, fast, reliable | MONSTR::HUGHES | Walk like an Alien | Tue Jul 14 1987 15:33 | 69 |
| ...pick any two...
We could reduce the cost of access to space without resorting to
exotic technology. In fact, taking the exotic route is one of the
reasons the shuttle is nowhere near as cost effective as was promised.
With existing chemical rocket technology, $/ton in leo could be reduced
significantly if that were the primary objective. It would require
a long term commitment and a reasonable lack of interference on
the part of elected representatives whose primary concern is how
to get themselves re-elected in 3 or 4 years time...
I would envisage something like...
- build a large expendable launch vehicle (LELV) whose primary
objective is 'cheap' with a secondary view towards reusability (to my
mind this suggests that parallel staging would be a major candidate)
- when the LELV is operational, investigate recovering/reusing some
components, e.g. a flyback booster in a serially staged system or
recovering booster stages in a parallel staged system
- once some degree of reusability is accomplished in the LELV,
concetrate on complete reusability
- concentrate on payload to low earth orbit
- develope orbital transfer vehicles (OTV) to carry payloads from LEO
to higher orbits or escape trajectories. Design the OTVs to be cheap
enough to be used for one shot missions but not to preclude reuse in
the future
- when the OTV is operational, investigate reuse and refueling
possibilities
- design a man-rated vehicle that can be carried by the LELV and
its successors. Reliability should come from making the man carrying
vehicle fault tolerant and not by attemtpting to make the LELV
inherently reliable, i.e. the burden for recovering from a major
malfunction should be on the man carrying vehicle and not the LELV
- the initial goals of the man carrying vehicle should be safety,
SAFETY and recoverability, i.e. a controlled reentry and landing.
A very close second would be reusability of the manned vehicle
(probably before the LELV).
- in the long term investigate replacing the OTV with exotic
technologies such as nuclear or solar powered propulsion
At this stage, I think we would be ready to actively work on exotic
systems to get large payloads to LEO.
If this sounds familiar, it is probably because someone has thought
of it before me...
re: non-nuclear Orion-type vehicles
What makes you think conventional chemical explosives are more
efficient than LOX/LH2 or FLOX/LH2 type systems? Or even conventional,
'non-high energy' propellants for that matter?
re: laser launching
I'd like to hear or read more about this. What is it that makes
it appear so attractive?
gary
|
| 311.7 | Hot air launch vehicles | MONSTR::HUGHES | Walk like an Alien | Tue Jul 14 1987 15:51 | 6 |
| re .5
Yeah, maybe something like that is needed. Either that or a launch
vehicle that burns LOX/politicians... :-)
gary
|
| 311.8 | Laser Launchers | SOFBAS::WOLFF | | Wed Jul 15 1987 09:07 | 27 |
| Laser Launching.
It appears so attractive to me for a number of reasons which
don't necessarily mean it is the most efficient means of getting
into orbit. So let me explain.
1) A 'free electron' laser (theoretically) is a very efficient
means of transforming electric power into a light beam. Pottentially
much greater than 20%.
2) A well focused laser beam, tuned to the right frequency has
been shown to very efficiently vaporize certain solid materials.
If the beam is pulsed at the right pulse-per-minute rate a highly
efficient rocket engine results.
3) The power for the engine remains on the ground while the
boost vehicle consists of cargo, vehicle shell, and propulsion reaction
mass. Everything which gets to orbit is useable in one way or another
in orbit with no wastage.
4) Modelling shows that laser launchers have the highest cargo
to weight percentage of ANY kind of launch methodology.
Laser Launchers have one big draw back, they can't be built
now. They require one major technological breakthrough: High
Temperature Super-Conductors. The free-electron laser is not
economical until room-temp SC's are available. When that happens
and the test lasers are built (for SDI is for no other reasons)
I think we'll all see some more interest in Laser Launchers.
The most promising thing for Laser Launchers is that room-temp
SCs may not be so far away! Some researchers have already detected
good signs in materials as high as 98 degrees F!!!!!
|
| 311.9 | | MONSTR::HUGHES | Walk like an Alien | Wed Jul 15 1987 10:08 | 26 |
| Interesting.
But, much of a LV's energy is spent accelerating the payload to orbital
velocity in a 'horizontal' direction, not straight up. Consider the
shuttle - when it is about 60 miles up it is spending most of its
energy accelerating down range and is climbing relatively slowly. This
would mean that the reaction mass would have to be expelled in a
different direction than the incoming laser beam making for a much
more complex system on board the LV, in effect a laser fired motor.
The beam would have to be fired at some sort of inlet that would
not allow vaporised reaction mass to escape. Thus not 'everything that
gets to orbit' is useable.
> 2) A well focused laser beam, tuned to the right frequency has
I think this is a problem that is not easily dismissed. It is a major
problem area for the SDI folks and all they are trying to do is
concentrate the beam enough to destroy warheads or satellites. Laser
launching would require even finer control since destroying the LV is
not the objective.
If that becomes possible laser launching may become attractive for
sending payloads to escape velocity, where up is where you want to
go (but you specifically asked about launcing to earth orbit).
gary
|
| 311.10 | Niven did it first | VINO::DZIEDZIC | | Wed Jul 15 1987 11:52 | 14 |
| Something on an aside, it was Larry Niven who popularized the
idea of laser propulsion in the sci-fi media. Pournelle did
several collaborations with Niven after Niven's original
stories which is probably where Pournell got his ideas.
One of Niven's favorite schemes for laser propulsion was a
LARGE laser on the vehicle itself. It wouldn't develop a
great deal of thrust, but it could thrust for a long time
(as long as there was energy to power it!) and so develop
a great deal of velocity. It also made a neat (defensive)
weapon when the occupants were attacked by aliens (Kzinti).
So much for sci-fi.
|
| 311.11 | | CLOSUS::TAVARES | John--Stay low, keep moving | Wed Jul 15 1987 17:59 | 9 |
| Tell ya what gang, I'm betting that our recent breakthroughs in
superconductivity will soon allow us to build magnets that will
have sufficient density to neutralize the earth's magnetic field.
Then we'll float all that junk up a la flying saucer.
I think that we'll soon find that some of those contactees
weren't lying about how one of those things works, either.
No, I'm not a flying saucer nut.
|
| 311.12 | howzabout gravity? | MORRIS::TRANDOLPH | | Thu Jul 16 1987 09:37 | 3 |
| >Then we'll float all that junk ...
You're gonna have to neutralize *gravity* to do that... -Tom R.
|
| 311.13 | RE 311.12 | EDEN::KLAES | The Universe is safe. | Thu Jul 16 1987 10:04 | 4 |
| Well, just build antigravity lifters...
Larry
|
| 311.14 | | CLOSUS::TAVARES | John--Stay low, keep moving | Thu Jul 16 1987 13:47 | 12 |
| No, I don't mean antigravity, I mean using a very powerful magnet
to float a load up into space. I read somewhere that the
required field density is in the order of several thousand gauss
(that was years ago, I could be way off). Last week I saw
something that predicted magnets in the order of several hundred
gauss within the next 5 years, using superconducting techniques.
I think they'll be there in say, 50 - 100 years. I don't think
that the laser drive will be developed any faster.
We're using magnetic fields to float things now in the
laboratory; I think we've been doing this for about 20 years now.
|
| 311.15 | The military way - 20 yr old technology | ANGORA::TRANDOLPH | | Thu Jul 16 1987 19:03 | 22 |
| I may be wrong, but haven't most of the magnetic "floating" experiments
up to now been performed by one magnet (anchored on the ground)
repelling another (floating) ? I'm thinking of the "maglev" trains
and such that have been attempted. I don't think that Earth's magnetic
field is strong enough for this stuff - take a compass needle as
an example. It takes almost nothing at all to turn it contrary to
it's preferred orientation. Now bring the compass close to a powerful
permanent magnet - you can't move the needle, except maybe by
physically grabbing it and forcing it around.
Of course, I guess you could put one *big* superconducting magnet
on the ground, and one on the "ship", but I don't think you could
do much more than go straight up.
Anyway, my thought is that we should have done the shuttle the right
way to begin with - runway launch, air breathing (where possible),
good old fashioned brute force. There's no technological reason at all
why we couldn't have had it well before now. The runway launch/air
breathing technology has existed for some time in the SR71 turbo/ramjet
setup. Cross it with the X-15 and you have your aerospace plane.
Making it big enough to lift ten tons of cargo is just a matter
of scale... bigger, stronger, more powerful. -Tom R.
|
| 311.16 | Maglev is alive and well in England | JANUS::BARKER | | Fri Jul 17 1987 06:26 | 16 |
| > I may be wrong, but haven't most of the magnetic "floating" experiments
> up to now been performed by one magnet (anchored on the ground)
> repelling another (floating) ? I'm thinking of the "maglev" trains
> and such that have been attempted.
Some maglev things may use repulsion, but most either induce eddy currents
into aluminium rails (more commonly used for propulsion with the linear
induction motor) or use the attraction between an electromagnet and steel
rails for levitation. Attractive electromagnets require to be servo-
controlled to maintain a constant ride height with varying loads.
Meglev trains have been more than attempted. There has been a maglev
"people mover" train in operation between the airport and train station in
Birmingham, England for some time.
jb
|
| 311.17 | some more thoughts... | SOFBAS::WOLFF | | Mon Jul 20 1987 09:07 | 19 |
|
reply 311.6 seems to be most on the mark. From reading the other notes
in this conference dealing with the Russians and the Europeans it seems
that they are pursuing that very path.
Are we in the US on the verge of being passed by because we are
technologically the best? We've spent so much effort building the BEST
and most ELEGANT shuttle system. But is it the right platform for our
needs?
I don't think so. If the Europeans get it together in the '90s the
way their plans could work, they will be much more economically
efficient than we are. Then we'll be buying space on their boosters.
But is that so bad?
Is the shuttle a military vehicle, explorational vehicle, or
commercial vehicle? What is its purpose, and what is our purpose? I
don't think its the right vehicle for the job that we want done, ie an
economically viable means of getting tons into orbit.
Any comments?
|
| 311.18 | The shuttle tries to be all things to all men | JANUS::BARKER | | Tue Jul 21 1987 07:24 | 13 |
| > Is the shuttle a military vehicle, explorational vehicle, or
> commercial vehicle?
NASA wanted an explorational/scientific vehicle.
DoD wanted a military vehicle.
It was decided to do commercial work to help pay for running costs.
The result was a huge compromise, which means that the shuttle is hugely
expensive to run and does none of its jobs superbly well.
JB
|
| 311.19 | Whats better then the shuttle | JETSAM::ANDRADE | The sentinel (.)(.) | Tue Jul 21 1987 09:52 | 7 |
| re .18
Never heard nothing agaisnt the shuttle until one blew up.
Lets not go too overboard about it, in spite of everything
the shuttle is still the best ground to orbit vehicle this
world has ever seen.
|
| 311.20 | | MONSTR::HUGHES | Walk like an Alien | Tue Jul 21 1987 12:00 | 35 |
| re .19
A LOT of people have been very critical of the shuttle from the
early 70s, when the design started to solidify, onwards. As .18 says,
it was a massive compromise with many, many non-tech's making
unilateral changes to the design criteria (the boosters for example
changed between solid/liquid and expendable/reuseable several times
and solid-reuseable was probably the worst possible choice).
It did not get much coverage in the popular press (read no coverage)
as the average 'man on the street' is not supposed to be interested
and NASA was working hard to maintain the 'Pollyanna' image.
Like many other activities, it becomes fair more public when something
goes catastrophically wrong.
The tile problems on the first flight got publicity, but not much
publicity was given to the deforming of several major structural
components of the orbiter on the same flight. Two flights at least have
come very close to nozzle burn through on the SRBs and I don't rcall
that getting much publicity either.
NASA has managed to pull back from the brink of disaster on several
flights - the shuttle has to fly at the hairy edge of its performance
envelope on nearly every flight. My personal, semi-educated guess (made
in the late 70s) was that it had about a 1 in 25 chance of catastrophic
failure. Unfrotunately, NASA began to believe its own PR and began
to ignore the risks.
It is not 'the best ground to orbit vehicle this world has ever seen'
by a long shot. It IS the world's first semi-reuseable spacecraft and
the first controlled return manned spacecraft, both of which are major
achievements.
gary
|
| 311.21 | What now | JETSAM::ANDRADE | The sentinel (.)(.) | Tue Jul 21 1987 15:46 | 20 |
| re .20
Thanks, for clarifying that. I get most my info from public sources.
I believed that the overall shuttle design, was very sound and had
safety as its top goal. With all the other goals secondary (in
another words, they would have cancelled rather then release an unsafe
vehicle) I also believed that the suttle was performing well within
its performance envelope.
Somehow I got the idea that the big risks in the shuttle bussiness
came from, first the new technologies in it (this always true with
new stuff), and second from manufacturing mistakes etc...
And not from a limitation of the master design itself.!!!!!!!!!!!!
So what should the US do, give up on the shuttle as a bad job.
And start a new from scratch. Or redesign the shuttle top/down
building more safety factors in. Or just go on as its currently
doing, that is going ahead with a basically unsafe vehicle with
just a few more small safety features added in.
|
| 311.22 | random thoughts on the shuttle | MONSTR::HUGHES | Walk like an Alien | Wed Jul 22 1987 09:37 | 27 |
| Although compromised, the shuttle is a workable design and a powerful
vehicle for manned access to LEO. But it should be treated as the
experimental vehicle that it still is. We are not yet at the point
of 'routine access to space'.
Having chosen to take the high tech road, NASA still needs to treat
manned space flight as a high risk operation. Amongst other things,
this means not carrying along passengers like teacher and politicians
(well, okay, you can take politicians up, but not bring them back :-)
Some major rethinking should be done around vehicle safety. I expect
it will fly without major new fault recovery capabilities. Hopefully
NASA won't get too cocky when it has another 20 successful missions
under its belt.
It also means that using it to launch satellites is potentially exposing
astronauts to high risk for little scientific return. Satellites
that do not require astronauts to be present at deployment should
be relegated to ELVs. Until the Titan 4/Centaur G-Prime is flying
I expect there will be some payloads that must fly on the shuttle.
The shuttle system is evolving and improving but I doubt that it will
ever be the 'space truck' NASA hoped it would be. Hopefully Shuttle 2
will fill that role, based upon the technology and experience of the
current shuttle.
gary
|
| 311.23 | Spaceflight with magsails | VERGA::KLAES | All the Universe, or nothing! | Thu Apr 02 1992 14:39 | 7 |
| The May 1992 issue of ANALOG SCIENCE FICTION AND FACT magazine
has a somewhat technical article by Robert M. Zubrin on magnetic
sail spacecraft. The article discusses the concept of vehicles
which use celestial magnetic fields to move in space.
Larry
|
| 311.24 | Canonical List of Space Transport Methods | VERGA::KLAES | Quo vadimus? | Tue Feb 22 1994 17:49 | 526 |
| Article: 827
From: [email protected] (Dani Eder)
Newsgroups: sci.space.tech
Subject: Canonical List of Space Transport Methods v0.3
Date: 17 Feb 94 18:18:58 GMT
Organization: Boeing AI Center, Huntsville, AL
Canonical List of Space Transport Methods
-----------------------------------------
Version 0.3 15 February 1994
by
Dani Eder
Net: [email protected]
Mail: Route 1, Box 188-2
Athens, AL 35611
FAX: (205) 461-2939
Voice: (205) 461-3731 (days, temp.)
(205) 232-7467 (home)
------------
Introduction
------------
This document is a list of all known space transport methods. The
list includes only those methods whose underlying physical principles
are understood (i.e. no warp drives as in Star Trek). This list is the
product of a number of years of collecting (and occasionally
inventing) space transportation methods. This is an early draft that
mostly lists the concepts. Later versions are intended to flesh out
each method with descriptions and references. If you know of a space
transport method which is not on this list, I would appreciate being
informed of it. If you have references or text descriptions on a
concept, they would be appreciated also.
Some related information on the basics of space transport, the forces
and energies involved, and concepts that affect transportation are
included. [Editorial comments appear in square brackets]
The List contains the following sections:
Section A: Basics of Space Transport
Section B: Propulsive Forces List
Section C: Energy Sources List
Section D: Propulsion Concepts List
Section E: Transportation-Related Concepts
------------------------------------
Section A: Basics of Space Transport
------------------------------------
A.1 The rocket equation
A.2 Staging
A.3 Orbit equations
---------------------------------
Section B: Propulsive Forces List
---------------------------------
B.1 Reaction Against Exhaust
B.1a Bulk Solid
B.1b Heated Gas
B.1c Combustion Gas
B.1d Plasma
B.1e Ion
B.1f Atomic Particle
B.1g Photon
B.2 External Interaction
B.2a Mechanical Traction
B.2b Cable Tension
B.2c Friction
B.2d Gas Pressure
B.2e Aerodynamic Forces
B.2f Photon Reflection
B.2g Solar Wind Deflection
B.2h Magnetic Field
B.2i Gravity Field
------------------------------
Section C: Energy Sources List
------------------------------
C.1 Mechanical Sources
C.1a Compressed Gas
C.1b Potential Energy
C.1c Kinetic Energy
C.2 Chemical Sources
C.2a Fuel-Atmosphere Combustion
C.2b Fuel-Oxidizer Combustion
C.3 Thermal Sources
C.3a Heated Storage Bed
C.3b Concentrated Sunlight
C.4 Electrical Sources
C.4a Power Line
C.4b Battery Storage
C.4c Magnetic Storage
C.4d Photovoltaic Array
C.4e Solar-Driven Turbine/Generator
C.4f Microwave Antenna Array
C.5 Power Beam Sources
C.5a Laser
C.5b Microwave
C.5c Neutral Particle
C.5 Nuclear Sources
C.5a Radioactive decay
C.5b Nuclear Fission
C.5c Nuclear Fusion
C.5d Nuclear Explosions
C.6 Matter Conversion Sources
C.6a Antimatter
C.6b Quantum Black Hole
-----------------------------------
Section D: Propulsion Concepts List
-----------------------------------
D.1 Structural Methods
D.1a Static Structures
[I have fleshed out this section as an example of the type of
material I would like to have in all the sections]
Static structures have parts which are mostly fixed in relation to
each other, although the structure as a whole may move with
respect to the ground. Large structures are primarily governed in
their design by the ratio of strength to density, or specific
strength. Other important properties in certain cases include
stiffness, temperature dependance of properties, and resistance to
decay from the surrounding environment.
Methods of movement on the structure include:
(i) Standard elevator:
Refer to standard engineering references for design details.
(ii) Inchworm type winch:
Cable anchor climbs up from one attachment point to the next while
cargo is attached to one point. Then cargo is hauled to next
attachment point. Useful where continuous attachment track or
full length elevator cable would be too heavy. Requires
independant power for winch.
(iii) Fluid transfer in pipes:
For example, Dr. Dana Andrews suggested pumping gas generated on
the Lunar surface up to it's L2 point. A column of Oxygen at .1
atmosphere at L2, and a temperature of 1000 K (a solar heated pipe
can be used to keep the gas hot) would have a pressure of 2310 atm
(34,000 psi) at the bottom.
Name: 1 Large Towers
Other Names:
Type: C.1b/B.2a (Potential Energy via Mechanical Traction)
Description:
Use of advanced aerospace materials makes possible the
construction of towers that are many kilometers tall. Such towers
can be used directly as a high altitude platform, as a launch
platform for a propulsive vehicle, or as a support structure for
an accelerator system. Structural design is a major issue.
If a tall structure is being considered, the weight of the tower
structure becomes the driving issue, because it can end up being
many times the weight of the 'payload' the tower is supporting.
If the 'payload' is at the top of the tower, the structure just
underneath only has to support the payload's weight. The next
piece of structure below that must support the payload -plus- the
top bit of structure, so it has to be a little bit beefier (have
a larger cross sectional area). Going down the structure, it has
to get stronger and stronger to support the greater weight above.
To put some numbers to the problem, let us take a plain carbon
steel structure (the type of steel used for ordinary building
construction). It has an allowable load of 18,000 psi. To
make the problem simple, assume we are holding up an 18,000 lb
payload on top of the tower, so we need exactly one square inch
of cross sectional area of steel to hold up the weight. Steel
has a density of 0.3 pounds per cubic inch. The top 10 feet
of the tower has 120 inches in height times 1 square inch in
cross section equals 120 cubic inches of steel. This weighs
36 pounds. So the structure 10 feet down from the top has to
support 18,036 lbs, and therefore has to have an area of 1.002
square inches. The area increases in a compound interest
fashion as you go down the tower.
To be mathematically exact, if we take the strength of the
material in pounds per square inch and divide by the density in
pounds per cubic inches, we get an number called the 'scale
height'. In this case, (18000psi)/(0.3lb/cu in) = 60000 inches =
5000 ft. So the scale height for plain carbon steel is 5000 ft.
Over each scale height of the structure, the cross sectional area
increases by a factor of e (2.71828...). So a tower 15000 ft tall
would have an area at the bottom e cubed (20.08) times the area at
the top, and the weight of steel would be e^3 - 1, or 19.08 times
the payload weight.
Now, plain carbon steel is not a very good material to use if you
want a really big tower. Let us look at advanced carbon
composites, such as is used in modern aircraft and spacecraft.
One specific formulation (Amoco T300/ERL1906 if you must know)
has a compressive strength of 280,000 psi. We derate this by half
to get the allowable load. This is the same as is done for the
steel, where you only use 50% of the strength to give you a safety
margin. So we have 140,000 psi as an allowable load. The density
is 0.066 lb/cu in. Dividing we have a scale height of 2,121,000
inches, or 176,800 feet, or 53.88 kilometers. If you build
several scale heights tall, you can see in theory you could build
structures hundreds of kilometers tall.
In reality you can't get quite this good a result. Most probably
your're payload won't all be at the top. And for the bottom 20
kilometers or so you will have to allow for wind loads, ice build-
up, and other such nasty things. Above this height, you have to
worry about atomic oxygen attacking your carbon/epoxy structural
material, so there will be some reduction in how high you can
build. But you still can build many times taller than anything
built so far.
Status: The tallest existing structure is a TV antenna which
is 2150 ft tall. Some engineering/architectural studies on very
large towers have been done. No attempts to build anything over
1000 meters tall are known. This concept should be within current
technology for structural materials, although it may require an
advance in construction techniques.
Variations:
1a Unguyed Mast
1b Guyed Mast
1c Series of Towers
References:
[to be inserted]
2 Orbital Tethers
2a Hanging Tether
2b Rotating Tether
3 High Altitude Balloon
4 Low-Density Tunnel
4a Hydrogen Tunnel
4b Evacuated Tunnel
D.1b Dynamic Structures
5 Fountain/Mass Driver
6 Launch Loop
7 Multi-Stage Tethers
D.2 Guns and Accelerators
D.2a Mechanical Accelerators
8 Leveraged Catapult
9 Rotary Sling
D.2b Artillery
10 Solid Propellant Charge
11 Liquid Propellant Charge
12 Gaseous Charge
12a Fuel-Oxidizer Charge
12b Scramjet Gun
D.2c Light Gas Gun
13 Pressure Tank Storage
14 Underwater Storage
15 Thermal Bed Heated
16 Particle Bed Reactor Heated
17 Electric Discharge Heated
18 Nuclear Charge Heated
19 Combustion Driven Piston
20 Gravity Driven Piston
D.2c Electric Accelerators
21 Railgun
22 Coilgun
D.3 Combustion Engines
D.3a Air-Breathing Engines
23 Fanjet
24 Turbo-Ramjet
25 Ramjet
26 Scramjet
27 Inverted Scramjet
28 Laser-Thermal JetJ
D.3b Internally Fuelled Engines
29 Solid Rocket
30 Hybrid Rocket
31 Liquid Rocket
D.4 Thermal Engines
32 Electric-Rail Rocket
33 Resistojet
34 Solar-Thermal
35 Laser-Thermal
36a Chamber Absorbtion
36b External Ablation
37 Solid Core Nuclear
38 Liquid Core Nuclear
39 Gas Core Nuclear
40 Muon-Catalyzed Fusion
D.5 Bulk Matter Engines
41 Rotary Flinger
42 Coilgun Engine
43 Railgun Engine
D.6 Ion and Plasma Engines
44 Arc Jet
45 Electrostatic Ion
45a Solar-Electric Ion
45b Thermoelectric Ion
45c Laser-Electric Ion
45d Microwave-Electric Ion
45e Nuclear-Electric Ion
46 Electron beam Heated Plasma
47 Microwave Heated Plasma
48 Fusion Heated Plasma
48a Reactor leakage mixed
48b Plasma Kernal Mixed
D.6 High Energy Particles
D.6a Particle Rockets
49 Pulsed Fission Nuclear (Orion)
50 Microfusion
51 Alpha Particle
52 Fission Fragment
53 Fusion Particle
53a Magnetic Confinement
53b Inertial Confinement
53c Electrostatic Confinement
54 Antimatter Annihilation
D.6b External Particle Interaction
55 Magsail
56 Particle Beam
57 Interstellar Ramjet
58 Interstellar Scramjet
D.7 Photon Engines
D.7a Photon Sails
59 Solar Sail
60 Laser Lightsail
61 Starwisp
D.7b Photon Rockets
62 Thermal Photon Reflector
63 Quantum Black Hole Generator
D.8 External Interactions
64 Ionospheric Current Loop
65 Gravity Assist
66 Dumb-Waiter
67 Aerobrake
68 Rheobrake
------------------------------------------
Section E: Transportation-Related Concepts
------------------------------------------
E.1 On-site resource use
69 On-site fuel extraction
70 Comet consumption en-route
71 Solar Sails from FeNi Asteroid
72 Structural materials
73 Solar Power Stations
73a Planet Surface
73b Orbiting
74 Atmospheric Laser
E.2 Payload Mass/Volume Minimization
75 Closed Life Support
76 Inflatable Structures
77 Recycling upper stages
78 Fabricators/Replicators
79 Nanofax Transmitter
--------------------------
Section F: General References
--------------------------
References [F1] to [F18] contain data about two or more propulsion concepts:
[F1] Byers, David C.; Wasel, Robert A. "NASA Electric Propulsion
Program", NASA Technical Memorandum 89856, May 1987.
[F2] Forward, R. L. "Advanced Space Propulsion Study - Antiproton
and Beamed Power Propulsion", Final Report, 1 May 1986 - 30 Jun
1987,J Hughes Research Laboratories, report AFAL-TR-87-070, 1987.
[F3] Forward, R. L. "Exotic Propulsion in the 21st Century", in
Aerospace Century XXI (see reference [8]).
[F4] Harvego, E. A.; Sulmeisters, T. K. "A Comparison of
PropulsionJ Systems for Potential Space Mission Applications",
ASME WinterJ Meeting, Boston, Massachusetts, 13 December 1987, 1987.
[F5] Kerrebrock, J. L "Report of the National Commission on Space -
One Commissioner's View", in Aerospace Century XXI (see reference [8]).
[F6] Korobeinikov, V. P. "On the Use of Solar Energy for the
Acceleration of Bodies to Cosmic Velocities", Acta Astronautica,
v 15 no 11 p 937-40, November 1987.
[F7] Matloff, G. L. "Electric Propulsion and Interstellar Flight",
19th International Electric Propulsion Conference, Colorado
Springs, Colorado, 11 May 1987.
[F8] Morgenthaler, G. W.; Tobiska, W. K. "Aerospace Century XXI:
Space Flight Technologies", Proceedings of the 33rd Annual AAS
International Conference, Boulder, Colorado, 26-29 Oct. 1986.
Published as Advances in the Astronautical Sciences, vol 64, pt
2, 1987.
[F9] Phillips, P. G.; Redd, B. "Propulsion Options for Manned
Missions to the Moon and Mars", in Aerospace Century XXI (see
reference 8).
[F10] Faughnan, Barbara (ed.); Maryniak, Gregg (ed.) "Space
Manufacturing 5: Engineering with Lunar and Asteroidal Materials",
proceedingsJ of the 7th Princeton/AIAA/SSI Conference, Princeton,
New Jersey, 8-11J May 1985.
[F11] Wang, S.-Y.; Staiger P. J. "Primary Propulsion of Electro-
Thermal,J Ion and Chemical Systems for Space Based Radar Orbit
Transfer", AIAA/SAE/ASME/ASEE 21st Joint Propulsion Conference,
AIAA paper number 85-1477, 1985.
[F12] Jones, R. M. "Space Supertankers: Electric Propulsion
SystemsJ for the Transportation of Extraterrestrial Resources"
AIAA/SAE/ASME 20th Joint Propulsion Conference, AIAA paper number
84-1323, 1984.
[F13] Jones, R. M.; Kaplan, D. I.; Nock, K. T. "Electric
PropulsionJ Systems for Space Stations" AIAA/SAE/ASME 19th Joint
Propulsion Conference,J AIAA paper number 83-1208, 1983.
[F14] Poeschel, R. L. "Comparison of Electric Propulsion
Technologies",J AIAA paper number 82-1243 presented at
AIAA/SAE/ASME 18th Joint PropulsionJ Conference, Cleveland, Ohio,
21-23 June 1982.
[F15] Diesposti, R. S.; Pelouch, J. J. "Performance and Economic
Comparison of Externally Energized vs Chemically Energized Space
Propulsion",J AIAA paper number 81-0703 presented at 15th
International Electric Propulsion Conference, Las Vegas, Nevada,
21-23 June 1981.
[F16] Kunz, K. E. "Orbit Transfer Propulsion and Large Space
Systems",J J. Spacecraft and Rockets vol 17 no 6 pp 495-500, Nov.-
Dec.J 1980.
[F17] Parkash, D. M. "Electric Propulsion for Space Missions",
Electr. India vol 19 no 7 pp 5-15, 15 April 1979.
[F18] Loeb, H. W. "Electric Propulsion Technology Status and
Development Plans - European Programs (Space Vehicles)", J.
Spacecraft andJ Rockets, vol 11 no 12 pp 821-8, Dec. 1974.
----------
Notes:
----------
This section has unconsolidated notes
Name:
Alternate Names:
Type:
Description:
Status:
References:
--
A higher intelligence, formerly from the Bubbleworld on the far side
of the Galaxy, now masquerading as a human engineer.
|
| 311.25 | Canonical List Version 0.6 | JVERNE::KLAES | Be Here Now | Mon Mar 07 1994 16:01 | 2282 |
| Article: 996
From: [email protected] (Dani Eder)
Newsgroups: sci.space.tech
Subject: Canonical List of Space Transportation Methods v0.6
Date: 2 Mar 94 16:05:41 GMT
Organization: Boeing AI Center, Huntsville, AL
Canonical List of Space Transport Methods
Version 0.6 1 March 1994
Dani Eder
Route 1, Box 188-2
Athens, AL 35611
[email protected]
Introduction
This document is a list of all known space transport methods. It includes
only those methods whose underlying physical principles are understood
(i.e. no warp drives as in Star Trek). It is the product of a number of years
of collecting - and occasionally inventing - space transportation methods.
This draft (v. 0.6) lists the concepts, with at least a basic description of
each method. Later versions are intended to flesh out each method with
improved descriptions and more current references. If you know of a space
transport method which is not on this list, I would appreciate being
informed of it. If you have references or text descriptions on a concept,
they would be appreciated also.
Some related information on the basics of space transport, the forces and
energies involved, and concepts that affect transportation are included.
[Editorial comments and material that needs lots of editing appear in square
brackets]
The List contains the following sections:
Section A: Basics of Space Transport
Section B: Propulsive Forces List
Section C: Energy Sources List
Section D: Propulsion Concepts List
Section E: Transportation-Related Concepts
Section A: Basics of Space Transport
A.1 The rocket equation
A.2 Staging
A.3 Orbit equations
A.4 Ascent Trajectories
Circular orbit velocity at the earth's surface is 7910 meter/sec. At the
equator, the Earth rotates eastward at 465 meters/sec, so in theory a
transportation system has to provide the difference, or 7445 meters/sec.
The Earth's atmosphere causes losses that add to the theoretical velocity
increment for many space transportation methods.
In the case of chemical rockets, they normally fly straight up intially, so as
to spend the least amount of time incurring aerodynamic drag. The vertical
velocity does not contribute to the circular orbit veloicty (since
they are perpendicular), so an optimized ascent trajectory rather quickly
pitches down from vertical towards the horizontal. Just enough climb is
used to clear the atmosphere and minimize aerodynamic drag. The rocket
consumes fuel to climb vertically and to overcome drag, so it would achieve
a higher final velocity in a drag and gravity free environment. The velocity
it would achieve under these conditions is called the 'ideal velocity'. It is
this value that the propulsion system is designed to meet. The 'real
velocity' is what the rocket actually has left after the drag and gravity
effects. These are called drag losses and gee losses respectively. A real
rocket has to provide about 9000 meters/sec to reach orbit, so the losses are
about 1500 meters/sec,
or a 20% penalty.
A.5 Combining Methods
Section B: Propulsive Forces List
[This section lists the forces that can be used for space transport]
B.1 Reaction Against Exhaust
B.1a Bulk Solid
B.1b Heated Gas
B.1c Combustion Gas
B.1d Plasma
B.1e Ion
B.1f Atomic Particle
B.1g Photon
B.2 External Interaction
B.2a Mechanical Traction
B.2b Cable Tension
B.2c Friction
B.2d Gas Pressure
B.2e Aerodynamic Forces
B.2f Photon Reflection
B.2g Solar Wind Deflection
B.2h Magnetic Field
B.2i Gravity Field
Section C: Energy Sources List
[This section lists the emergy sources that can be used for space transport]
C.1 Mechanical Sources
C.1a Compressed Gas
C.1b Potential Energy
C.1c Kinetic Energy
C.2 Chemical Sources
C.2a Fuel-Atmosphere Combustion
C.2b Fuel-Oxidizer Combustion
C.3 Thermal Sources
C.3a Heated Storage Bed
C.3b Concentrated Sunlight
C.4 Electrical Sources
C.4a Power Line
C.4b Battery Storage
C.4c Magnetic Storage
C.4d Photovoltaic Array
[1] Anonymous "Conference Record of the Nineteenth IEEE Photovoltaic
Specialists Conference- 1987", New Orleans, Louisiana, 4-8 May 1987.
[2] Anonymous "NASA Conference Publication 2475: Space Photovoltaic
Research and Technology 1986: High Efficiency, Space Environment, and Array
Technology", Cleveland, Ohio, 7-9 October 1986.
[3] Chubb, Donald L. "Combination Solar Photovoltaic Heat Engine Energy
Converter", Journal of Propulsion and Power, v 3 no 4 pp 365-74, July-August
1987.J J
C.4e Solar-Driven Turbine/Generator
[1] Spielberg, J. I. "A Solar Powered Outer Space Helium Heat Engine", Appl.
Phys. Commun. vol 4 no 4 pp 279-84, 1984-1985.
C.4f Microwave Antenna Array
C.5 Beam Sources
C.5a Laser
C.5b Microwave
C.5c Neutral Particle
C.6 Nuclear Sources
C.6a Radioactive decay
[1] Lockwood, A.; Ewell, R.; Wood, C. "Advanced High TemperatureJ Thermo-
electrics for Space Power", Proceedings of the 16th Intersociety Energy
Conversion Engineering Conference, v 2 pp 1985-1990, 1981.
C.6b Nuclear Fission
[1] El Genk, M.S.; Hoover, M. D. "Space Nuclear Power SystemsJ 1986:
Proceedings of the Third Symposium", 1987.J J
[2] Sovie, Ronald J. "SP-100 Advanced Technology Program", NASAJ Technical
Memorandum 89888, 1987.
[3] Bloomfield, Harvey S. "Small Space Reactor Power Systems for Unmanned
Solar System Exploration Missions", NASA Technical MemorandumJ 100228,
December 1987.J J
[4] Buden, D.; Trapp, T. J. "Space Nuclear Power Plant TechnologyJ
Development Philosophy for a Ground Engineering Phase", ProceedingsJ of
the 20th Intersociety Energy Conversion Engineering ConferenceJ vol 1 pp
358-66, 1985.J J
C.6c Nuclear Fusion
[1] Miley, G. H. et al "Advanced Fusion Power: A preliminaryJ
Assessment, final report 1986-1987". National Academy of SciencesJ
report #AD-A185903, 1987.J J
[2] Eklund, P. M. "Quark-Catalyzed Fusion-Heated Rockets", AIAAJ paper
number 82-1218 presented at AIAA/SAE/ASME 18th Joint PropulsionJ
Conference, Cleveland, Ohio, 21-23 June 1982.
C.6d Nuclear Explosions
C.6 Matter Conversion Sources
C.6a Antimatter
[1] Hora, H.; Loeb, H. W. "Efficient Production of AntihydrogenJ by Laser for
Space Propulsion", Z. Flugwiss. Weltraumforsch.,J v. 10 no. 6 pp 393-400,
November-December 1986.
[2] Forward, R.L., ed. "Mirror Matter Newsletter", self published,
all volumes, contains extensive bibliography.
C.6b Quantum Black Hole
Section D: Propulsion Concepts List
[This section lists propulsion concepts, organized by type]
D.1 Structural Methods
D.1a Static Structures
Static structures have parts which are mostly fixed in relation to each other,
although the structure as a whole may move with respect to the ground.
Large structures are primarily governed in their design by the ratio of
strength to density, or specific strength. Other important properties in
certain cases include stiffness, temperature dependance of properties, and
resistance to decay from the surrounding environment.
Methods of movement on the structure include:
(i) Standard elevator:
Refer to standard engineering references for design details.
(ii) Inchworm type winch:
A small motor driven trolley pulls a length of cable behind it as it climbs up
the structure. It then hooks the cable to a fixed point on the structure. The
cargo elevator remains attached to the next lower point on the structure
during this time. The elevator then uses an on-board winch to reel itself up
from one attachment point to the next. This type of winch is useful where
continuous attachment track or full length elevator cable would be too
heavy. Requires independant power for winch.
(iii) Fluid transfer in pipes:
For example, Dr. Dana Andrews has suggested pumping gas generated on
the Lunar surface up to the Lunar L2 point. A column of Oxygen at .1
atmosphere at L2, and a temperature of 1000 K (a solar heated pipe can be
used to keep the gas hot) would have a pressure of 2310 atm (234 MPa) at
the bottom. Another approach is to have pumping stations spaced along the
tower.
1 Large Towers
Alternate Names:
Type: C.1b/B.2a (Potential Energy via Mechanical Traction)
Description:
Use of advanced aerospace materials makes possible the construction of
towers that are many kilometers tall. Such towers can be used directly as a
high altitude platform, as a launch platform for a propulsive vehicle, or as a
support structure for an accelerator system. Structural design is a major
issue.
If a tall structure is being considered, the weight of the tower
structure becomes the driving issue, because it can end up being many
times the weight of the 'payload' the tower is supporting. If the
'payload' is at the top of the tower, the structure just underneath
only has to support the payload's weight. The next piece of structure
below that must support the payload -plus- the top bit of structure,
so it has to be a little bit beefier (have a larger cross sectional
area). Going down the structure, it has to get stronger and stronger
to support the greater weight above.
To put some numbers to the problem, let us take a plain carbon steel
structure (the type of steel used for ordinary building construction). It has
an allowable load of 125 MPa. To make the problem simple, assume we
are holding up a 1275 kg payload on top of the tower, which under one
gravity has a weight of 12,500 N. Thereforewe need one square centimeter
of cross sectional area of steel to hold up the weight. Steel has a density of
7800 kg per cubic meter. The top meter of the tower has a volume of
0.01x0.01x1.0= 0.0001 cubic meter. This has a mass of 0.78kg. So the
structure 1 meter down from the top has to support a mass of 1275.78 kg,
i.e. the payload plus the top meter of steel. The load has increased by
0.06%, so the cross sectional area also increases by 0.06%. The area
increases in a compound interest fashion at the rate of 0.06% per meter as
you go down the tower. Over the course of 1 km in height, the increase is
by a factor of 1.8433.
We define the scale height of a structure as the length over which the cross
sectional area increases by a factor of e (2.71828...). In the case we have
been using it is 1635 meters. The scale height can be found by dividing the
allowable load of the material by the density times the local acceleration (one
gravity in the case of the Earth):
h(scale) = load / (density x acceleration)
= 125 MPa / (7800 kg/m^3 x 9.80665 m/s^2) = 1635 meters
So a tower 4.9 km tall would have an area at the bottom e cubed (20.08)
times the area at the top, and the weight of steel would be e^3 - 1, or 19.08
times the payload weight.
[ SI CONVERSION TO HERE ]
Now, plain carbon steel is not a very good material to use if you want
a really big tower. Let us look at advanced carbon composites, such
as is used in modern aircraft and spacecraft. One specific
formulation (Amoco T300/ERL1906 if you must know) has a compressive
strength of 280,000 psi. We derate this by half to get the allowable
load. This is the same as is done for the steel, where you only use
50% of the strength to give you a safety margin. So we have 140,000
psi as an allowable load. The density is 0.066 lb/cu in. Dividing we
have a scale height of 2,121,000 inches, or 176,800 feet, or 53.88
kilometers. If you build several scale heights tall, you can see in
theory you could build structures hundreds of kilometers tall.
In reality you can't get quite this good a result. Most probably your're
payload won't all be at the top. And for the bottom 20 kilometers or so you
will have to allow for wind loads, ice build- up, and other such nasty
things. Above this height, you have to worry about atomic oxygen
attacking your carbon/epoxy structural material, so there will be some
reduction in how high you can build. But you still can build many times
taller than anything built so far.
[ Compressive members support a payload at altitude. Advanced materials
make tall structures possible. Modern composite materials, for example
graphite/epoxy, have specific strengths (strength/weight) of many
kilometers. For example, T300 graphite/934 epoxy has a compressive
strength of 1.513 GPa (219.4 ksi) and a density of 1577 kg/m^3 (0.057J
lb/in^3). The specific strength is therefore 97.8 km at one gravity. It is
therefore possible to build guyed mast type towers many kilometersJ tall. If
the tower is used many times to support a launch system, the structural cost
(figure 3) would be justified. The top of the tower would be above most or
all of the atmosphere. This would significantly reduce drag and gravity
losses for any transportation system, and provide some initial altitude. The
tower will be considered in combination with other concepts. (note 1
million psi graphite is available)J] J J
Status:
The tallest existing structure is a TV antenna which is 2150 ft tall. Some
engineering/ architectural studies on very large towers have been done. No
attempts to build anything over 1000 meters tall are known. This concept
should be within current technology for structural materials, although it
may require an advance in construction techniques.
Variations:
1a Unguyed Mast
1b Guyed Mast
1c Series of Towers
References:
2 Tethers
Alternate Names: Beanstalks, Jacob's Ladder, Space Bridge,
Geosynchronous Towers
Type:
Description:
Tensile members in orbit store and transfer momentum to vehicles. The
tethers may be gravity-gradient stabilized or rotating endwise. A
ground-to- geosynchronous cable is not feasible with today's
structural materials. Tethers, of which a geosynchronous cable is a
special case, obey an exponential mass-ratio-to-payload-weight
relation similar to that for chemical rockets. It is possible, with
existing materials, to build tethers which will provide several km/s
of delta v. In a launch system application, an orbiting tether can be
set rotating so that the lower end travels slower than orbitalJ
velocity. A launch vehicle could rendezvous with the tether, drop a
payload, then release. Since only the payload remains in orbit,J the
propulsion system on the tether only has to provide momentum to add to
the payload; the launch vehicle never has to take itself to orbital
velocity. In this case the tether acts as a 'momentum bank', lending
velocity to the launch vehicle temporarily while the payload is unloaded.
Tethers are the generalization of the 'beanstalk' or geosynchronous tower
concept. In the original concept, a cable is placed so that it hangs vertically
over the equator, and is in a 24 hour orbit.J It thus appears to hang
vertically over one spot on the Earth. The task of reaching Earth orbit then
reduces to a very long (35,000 km) elevator ride. Unfortunately for the
original idea, tensile strengths approaching 2 million pounds per square inch
(12.5 GPa) are required for reasonable designs.
Tethers generalize on the original concept by (1) allowing any length,J (2)
allowing any orbital period, (3) allowing any swinging or rotating states,
and, (4) allowing multiple tethers to be connected in various geometries.
One simple case would be a tether vertically oriented in earth orbit, spanning
the altitudes from 300km to 2000km. A cargo could be carried on an
elevator over this altitude range. While it is not as elegant as the
geosynchronous case, it is constructable with existing materials.J J
Material strength to density ratio is the critical criterion for
designing tethers. To build a minimum mass tether, one wishes to taper
it's cross section by a factor of e per scale length. The scale
length is the length at which under one gravity, the weight of a
constantJsection cable equals the tensile strength (i.e. just breaks).
While the gravitational field around a planet is non-uniform, the
'depth' of the gravity well is equal to the surface gravity times the
radius of the planet. The following table shows the taper factors
derivedJ for each gravity well given materials available at different
times: [the table lost formatting when converted from Word - to be fixed ]
============================================================
===========J Taper Factors Required For Various Gravity
Wells and Technology Levels |
------------------------------------------------------------
------------
Gravity Depth ---------------- Time Period ------------
--
Well (km 1960s 1970s Early 1987
1990s
J @1g) 1980s
(est)
---------- ------ ----- ----- ----- -----
-----
Moon's 287 21 3.1 2.5 2.1
2.0
Mars' 1289 7.8E5 160 58 28
21
1/2 Earth's 3190 3.8E14 2.7E5 2.3E4 4000
1900
Earth's 6375 1.4E29 7.2E10 5.1E8 1.5E7
3.4E6J
------------------------------------------------------------
------------ Material Fiber- Kevlar
Carbon CarbonJ Carbon
J glass
Tensile Str. (MPa) 2410 3625 5650 6895
7650
Density (kg/m^3) 2580 1450 1810 1827
1840
Scale length (km@1g) 95 255 318 385
424
============================================================
============J J J
Status:
Variations:
2a Orbital Hanging Tether
2b Orbital Rotating Tether
2c Terrestrial Tether
One vehicle pulls another without direct mechanical attachment.J
Allows modification of one vehicle without reconfiguration of joined
pair. Allows one type of vehicle to pull another. Reduces loads on
lead vehicle by lift-to- drag ratio.J J J
References:
[1] Anderson, J. L. "Tether Technology - Conference Summary", AmericanJ
Institute of Astronautics and Aeronautics paper 88-0533, 1988.
[2] Carroll, J. A. "Tether Space Propulsion", AIAA paper 86-1389,J 1986.
[3] Ebisch, K. E. "Skyhook: Another Space Construction Project",J American
Journal of Physics, v 50 no 5 pp 467-69, 1982.J J J
3 Aerostat
Alternate Names: High altitude balloon
Type:
Description:
One approach to minimizing drag and gravity losses is to carry a vehicle
aloft with a high altitude balloon. Research balloons have carried ton-class
payloads in the range of 15-30 km high, which is above the bulk of the
atmosphere.
Status:
Variations:
References:
4 Low-Density Tunnel
4a Light Gas Tunnel
Alternate Names:
Type:
Description:
One or more light gas balloons are strung along the path of a vehicle or
projectile. The gas has a lower density than air. The formula for drag is
0.5CdrAv2, where r is the density. Thus the lower density will lower drag.
Status:
Variations:
References:
4b Evacuated Tunnel
Alternate Names:
Type:
Description: An evacuated tunnel is supported up through the atmosphere
(as by one or more towers). A launch system such as an electromagnetic
accelerator fires a projectile up through the tunnel. Drag losses are
minimized within the tunnel, and are low in the remaining part of the
atmosphere which must be traversed. If the top end requires some means of
keeping air from flowing in and filling the tunnel - such as a hatch that
remains closed until the accelerator is about to fire.
Status:
Variations:
References:
D.1b Dynamic Structures
Static structures rely on the strength of materials to hold themselves
up. Dynamic structures rely on the forces generated by rapidly moving
parts to hold up the structure. The advantage of this approach is it
can support structures beyond the limits of material strengths. The
disadvantage is that if the machinery that controls the moving parts
fails, the structure falls apart.
5 Fountain/Mass Driver
Alternate Names:
Type:
Description:
An electromagnetic accelerator provides a stream of masses moving up
vertically. A series of coils decelerates the masses as they go up, then
accelerates them back down again, at a few gravities. When they reach
bottom, the accelerator slows them down and throws them back up again, at
hundreds of gravities. Thus the accelerator is many times shorther than the
fountain height. The reaction of the coils to the acceleration of the fountain
of masses provides a lifting force that can support a structure. The lifting
force is distributed along where the coils are located. This can be along the
length of a tower, or concentrated at the top, with the stream of masses in
free-flight most of the way.
Status:
Variations:
References:
6 Launch Loop
Alternate Names:
Type:
Description:
A strip or sections of a strip are maintained at super-orbital
velocities. They are constrained by magnetic forces to support a
structure, while being prevented from leaving orbit. A vehicle rides
the strip, using magnetic braking against the strip's motion to
accelerate. Several concepts using super-orbital velocity structures
have been proposed. One is known as the 'launch loop'. In this
concept a segmented metal ribbon is accelerated to more than orbital
velocity at low Earth orbit. The ribbon is restrained from rising to
higherJ apogees by a series of cables suspended from magnetically
levitated hardware supported by the ribbons. The ribbon is guided to
ground level in an evacuated tube, and turned 180 degrees using
magnets on the ground. A vehicle going to orbit rides an elevator to
a station where the cable moves horizontally at altitude. The vehicle
accelerates using magnetic drag against the ribbon, then releases when
it achieves orbital velocity.J J J
Status:
Variations:
References:
7 Multi-Stage Tethers
Alternate Names:
Type:
Description:
A multi-stage tether has more than one tether, with the tethers in relative
motion. For example, a vertically hanging tether in Earth orbit can have a
rotating tether at it's lower end. The advantage of such an arrangement is to
lower the mass ratio of tether to payload compared to a single tether. The
mass ratio of a rotating tether is approximately proportional to exp(tip
velocity squared). If two tethers each supply half the tip velocity, then the
ratio becomes exp(2(tip velocity/2)squared), which is a smaller total mass
ratio.
Another feature of a multi-stage tether is that the tip velocity vector of the
two stages add. Since one rotates with respect to the other, the sum of the
vectors changes over time. Given suitable choices of tip velocities and
angular rates, one can receive and send payloads with arbitrary speed and
direction up to the sum of the two vectors.
Status:
Variations:
References:
D.2 Guns and Accelerators
D.2a Mechanical Accelerators
[ orphan concept : Tow-Rope (Terrestrial Tether) J
J J Reaction : One vehicle pulls another without direct mechanical
attachment.J Allows modification of one vehicle without reconfiguration of
joined pair.]
8 Leveraged Catapult
Alternate Names:
Type:
Description:
A leveraged catapult uses a relatively large or heavy driver to accelerate a
smaller payload at several gravities by mechanical means. Devices such a
multiple sheave pulley or a gear train convert a large force moving slowly to
a small force moving fast, and transmit the force along a cable.
The mechanical advantage produces more than one gravity of acceleration.
This concept may be the simplest to implement on a small scale. It consists
of a large weight connected via cableJ and pulley arrangement to a much
lighter projectile. The weight is allowed to fall under gravity, and the
projectile accelerates at much more than one gravity due to the mechanical
leverage of the pulley.J Despite the seeming simplicity of the concept,
velocities of severalJ km/s are possible, which would greatly reduce the size
of a rocket needed to provide the balance of the velocity.
The performance of this concept reaches a limit due to the weight, drag, and
heating of the cable attached to the payload and the magnitude of the driving
force, which is divided by the leverage ratio to yield the force on the
payload.
Status:
Variations:
8a Drop Weight
A falling mass is connected to a vehicle by a multiple-sheave pulley and
high strength cable. Two types of location are possibilities - river gorges
and mountain peaks. Locations such as the Grand Canyon and the
Columbia River gorge have lots of vertical relief for the drop weight. At
these locations the weight can consist of a large fabric bag filled with water
from the river at the bottom. The bag can be emptied before hitting bottom.
This reduces the weight that has to be stopped by a braking system.
For mountain peak locations, the drop weight runs down a set of rails and is
stopped by running into a body of water or running up an opposing hillside
plus possibly wheel braking. The mountain location may be preferred
because of the greater launch altitude.J
8b Locomotive Driver
A set of railroad locomotives provides the motive force, which is multiplied
by a gear mechanism to a higher speed.
8c Jet Driver
This is similar to the locomotive case, but the gear ratio is lower
since the jet can reach a higher speed on a take-off run.
References:
9 Rotary Sling
Alternate Names:
Type:
Description:
In principle, this is a sling or bolo scaled up and using aerospace materials.
A drive arm is driven in rotation by some means. A cable with the payload
attached to the end is played out gradually as the system comes up to speed.
The drive arm leads the cable slightly so the cable and payload see a torque
that continues to accelerate them. When the desired payload velocity is
reached, the payload releases and flies off. The cable is then retracted and
the drive arm slows down. When it stops, another payload is attached.
In a vacuum, such as on the Lunar surface, this is theoretically a very
efficient system, as the sling can be driven by an electric motor and the
mechanical losses can be held to a low value. Some method of recovering
the energy of the arm and cable (such as by transferring it to a second
system by using the motor as a generator), can lead to efficiencies over 60%
in theory.
On Earth such a system is hindered by air drag. One method of
reducing drag effects is to attach a shaped fairing to the cable
material, so as to lower drag compared to a circular cable. Another
is to mount the drive arm on the top of a large tower, so the cable is
not moving in dense air. A third is to generate lift along the cable
or at the payload, so the rapidly moving part of the cable, near the
payload, is at a high altitude, where there is less drag.
Status:
Variations:
References:
D.2b Artillery
10 Solid Propellant Charge
Alternate Names:
Type:
Description:Explosive vaporizes behind projectile in barrel. Gas pressure
accelerates projectile to high velocity. Conventional artillery reaches speeds
of around 1000 m/s.
Status: Artillery has a long history and extensive use. The High
Altitude Research Probe project attached two naval gun barrels in
series and used relatively light projectiles to reach higher muzzle
velocities than conventional artillery.
Variations:
References:
11 Liquid Propellant Charge
Alternate Names:
Type:
Description: Similar to conventional solid propellant artillery except liquid
propellants are metered into the chamber, then ignited. Liquid propellants
have been studied because they produce lighter molecular weight
combustion products, which leads to higher muzzle velocities, and because
bulk liquids can be stored more compactly than shells, and require less
handling equipment to load.
Status:
Variations:
References:
12 Gaseous Charge
12a Fuel-Oxidizer Charge
Alternate Names:
Type:
Description: Similar to conventional artillery except gaseous propellants are
metered into the chamber. This is essentially what happens in the cylinder
of a car engine, as a point of reference.
Status: Used as the driver for the Livermore gas gun (fuel-air mix drives 1
ton piston, which in turn compresses hydrogen working gas).
Variations:
References:
12b Scramjet Gun
Alternate Names:
Type:
Description:
Fuel/oxidizer mixture present in barrel is burned as projectile travels up
barrel. If projectile shape resembles two cones base to base, as in an inside-
out scramjet, the gas is compressed between the projectile body and barrel
wall. The combustion occurs behind the point of peak compression, and
produces more pressure on the aft body than the compression on the fore-
body. This pressure difference provides a net force accelerating the
projectile.
One attraction of this concept is that a high acceleration launch can
occur without the need for the projectile to use onboard propellants.
If the projectile has a inlet/nozzle shape (hollow in the middle) it
might continue accelerating in the atmosphere by injecting fuel into
the air-only incoming flow, extending the performance beyond what a
gun alone can do. Another attraction of this conceptJ is the
simplicity of the launcher, which is a simple tube capableJ of
withstanding the internal pressure generated during combustion.
Status: Research being performed at the University of Washington under
Prof. Adam Bruckner. Research gun in basement of building.
Variations:
References:
13 Rocket Fed Gun
Alternate Names:
Type:
Description: Rocket engine at chamber end of gun produces hot gas
to accelerate projectile. In a conventional gun, all the gas is
formed at once as the charge goes off. In this concept the gas is
produced by a rocket type engine and fills the barrel with gas as the
projectile runs down it. Compared to a conventional gun, the peak
pressure is lower, so the barrel is lighter.
Status:
Variations:
References:
D.2c Light Gas Gun
Light gas guns are designed to reach higher muzzle velocities than
combustion guns. They do this by using hot hydrogen (or sometimes
helium) as the working gas. These have a lower molecular weight, and
therefore a higher speed of sound. Guns are strongly limited by the speed
of sound of the gas they use. The drawback to light gas guns is that the gas
does not generate high pressures and temperatures by itself (as do
combustion byproducts). Therefore some external means are required to
produce the gas conditions desired.
14 Pressure Tank Storage
Alternate Names:
Type:
Description: The gas is stored in a chamber, then adiabatically expandedJ
in a barrel, doing work against a projectile.J
Status:
Variations:
References:J J J
[1] Taylor, R. A. "A Space Debris Simulation Facility for Spacecraft Materials
Evaluation", SAMPE Quarterly , v 18 no 2 pp 28-34, 1987.
15 Underwater Storage
Alternate Names:
Type:
Description:
In a gas gun on land the amount of structural meterial in the gun is governed
by the tensile strength of the barrel and chamber.J In an underwater gun, an
evacuated barrel is under compression by water pressure. The gas pressure
in the gun can now be the external wat er pressure plus the pressure the
barrel wall can withstand in tension, which is up to twice as high as the land
version.
Other features of an underwater gun are the ability to store gas with very
little pressure containment (the storage tank can be in equilibrium with the
surrounding water), and the ability to point the gun in different directions
and elevations.
The underwater gas gun consists of a gas storage chamber at some depth in
a fluid, in this case the ocean, a long barrel connected to a chamber at one
end and held at the surface by a floating platform at the other end, plus some
supporting equipment.
TheJchamber is a made of structural material such as steel.J An inlet pipe
allows filling of the chamber with a compressed gas.J A valve is mounted
on the inlet pipe. An outlet pipe of larger diameter than the inlet pipe
connects to the gun barrel. An outlet valve is mounted on the outlet pipe.
This valve may be divided into two parts: a fast opening and closing part,
and a tight sealing part.J The interior of the chamber is lined with
insulation. The inner surfaceJ of the insulation is covered by a refractory
liner, such as tungsten.J An electrical lead is connected to a heating element
inside the chamber.J
An inert gas such as argon perfuses the insulation. The inert gas protects
the chamber structure from exposure to hot hydrogen, and has a lower
thermal conductivity. An inert gas fill/drainJline is connected to the volume
between the chamber wall and the liner.J A pressure actuated relief valve
connects the chamber with a volume of cold gas. This cold gas is
surrounded by a flexible membrane such as rubber coated fiberglass cloth.
In operation, the gas inside the chamber, the inert gas, and the
waterJoutside the chamber are all at substantially the same pressure. Thus
the outer structural wall does not have to withstand large
pressureJdifferences from inside to outside. One part of the chamber wall
is movable, as in a sliding piston, to allow variation in the
chamberJvolume. The gas in the chamber is preferably hot, so as to
provide the highestJmuzzle velocity for the gun. When the gun is operated,
this gas is released into the gun barrel. In order to preserve the small
pressure difference across the wall of the chamber, either the chamber
volume must decrease or gas from an adjacent cold gas bladder must replace
the hot gas as it is expelled. This arrangement prevents ocean water from
contactingJ the chamber walls or hot gas.J J In the case of the sliding
piston, the membrane collapses, with theJ gas formerly within it moving in
behind the piston. In the alternateJ case, the membrane also collapses, with
the gas formerly within it moving through a valve into the chamber.
The chamber has an exit valve which leads to the gun barrel. It also has gas
supply lines feeding the interior of the chamber and the volume between the
chamber walls.J These lines are connected to regulators which maintain
nearly equalJ gas pressures, which in turn are nearly equal to the ocean
pressure.J This allows the chamber to be moved to the surface for
maintenance, and to be placed at different depths for providing different
firingJ pressures or different gun elevations.
The muzzle of the gun is at the ocean surface, so elevation of the gun can be
achieved by changing the depth of the chamber end. SinceJthe gun as a
whole is floating in the ocean, it can be pointed inJany direction. Some
means for heating the gas stored in the chamberJ is needed, such as an
electric resistance heater. At the muzzle endJof the gun, a tube surrounds
the barrel, with a substantial volumeJin beween the two. There are
passages through the wall of the barrelJthat allow the gas to diffuse into the
tube rather than out the endJ of the gun, thus conserving the gas.
At the muzzle of the gun is a valve which can rapidly open, and anJejector
pump which prevents air from entering the barrel. In operation,Jthe ejector
pump starts before the gun is fired, with the valve shut.J The valve is
opened, then the gun is fired. In this way, the projectileJencounters only
near vacuum within the barrel, followed by air.
Status:
Variations:
References:
16 Thermal Bed Heated
Alternate Names:
Type:
Description:
Hot gas is generated by flowing hydrogen through a chamber which
contains refractory oxide particles. The particles are heated slowly (roughly
1 hour time period) by some type of heater near the center of the chamber.
This sets up a temperature gradient, so the exterior of the chamber is
relatively cool, and can thus be made of ordinary steels. When the
hydrogen flows through the chamber, the large surface area of the particles
allows very high heat transfer rates - so the heat in the chamber can be
extracted in a fraction of a second.
Status: A small research gun of this type has been built at
Brookhaven Natl. Lab.
Variations:
References:
17 Particle Bed Reactor Heated
Alternate Names:
Type:
Description:
Hot gas is generated by flowing through particle bed typeJreactor. Gas
expands against projectile, accelerating it. LightJgas guns have been
operated to above orbital velocity, and 1 kg projectilesJhave been
accelerated to over half orbital velocity. This type of gun rapidly becomes
less efficient above the speed of sound ofJthe gas. As a consequence the
working fluid is usually hot hydrogen.J Conventional gas guns have used
powder charge driven pistons to compress and heat the gas. This is not
expected to be practical on the scale needed to launch useful payloads to
orbit. One way to heat the gas is to pass it through a small particle bed
nuclear reactor. This type of reactor produces a great deal of heat in a small
volume, since the small particles of nuclear fuel have a large surface/volume
ratio and can efficiently transfer the heat to working fluid. This uses the
benefits of nuclear power for space launch, without the drawbacks of a
flying reactor.
Status:
Variations:
References:
18 Electric Discharge Heated
Alternate Names:
Type:
Description:
Gas is heated by electric discharge, then expands against projectile
in barrel. The limiting factor for a light gas gun is the speed of
sound in the gas. One way to heat the gas toJ much higher
temperatures is an electric discharge within the gas.
Status:
Variations:
References:
J
19 Nuclear Charge Heated
Alternate Names:
Type:
Description: Similar to artillery, except explosive in chamber is
atomic bomb. This concept makes sense in a situation where very large
payloads need to be launched. A large underground chamber is
excavated, and filled with hydrogen gas as the working fluid. A large
barrel leads off the chamber upward at an angle. A crossbar is set
into the barrel near the chamber, and the projectile is attached to
the crossbar with a bolt that is designed to fail at a pre-determined
stress. This keeps the projectile in place until the operating
pressure is reached. A small atomic bomb is suspended in the chamber
and detonated to create lots of hot hydrogen in a very short time.
Status:
Variations:
References:
20 Combustion Driven Piston
Alternate Names:
Type:
Description: This is a type of two-stage gas gun. A cylindrical chamber
contains a piston. On the back side of the piston high pressure gas is
generated by combustion. This can be gunpowder or a fuel-air mixture. On
the front side of the piston is the working gas, which is usually hydrogen.
The hydrogen is compressed and heated until a valve or seal is opened.
Then the working gas accelerates the projectile.
Status:
Variations:
References:
21 Gravity Driven Piston
Alternate Names:
Type:
Description:
A sliding or falling mass is used to compress gas in a chamber. The
gas is then expanded in a barrel. An alternate method of compressing
and heating the working fluid in a light gas gun is a rapidly moving,
massive piston. If the gun is built on the side of a mountain, the
energy for launch is stored as potential energy in the piston. The
piston is levitated on an air or lubricated bearing and slides down
the mountain to a cylinder.J The cylinder leads to a barrel containing
the projectile, which accelerates upward.
Status:
Variations:
References:
D.2d Electric Accelerators
Electric accelerators typically require high peak power for a short period of
time. Hence inexpensive energy storage is very important for these
concepts. Two places to look for inexpensive energy storage are (1)
Magnetic fusion experiments, and (2) Inductive energy stores. The latter
falls into subcategories: cooled normal conductors, and superconductors.
22 Railgun
Alternate Names: Electromagentic Gun
Type:
Description:
High current electricity supplied by rails is shorted through plasma arc.
Plasma is accelerated by reaction against magnetic field produced by
current. Plasma pushes projectile. A railgun uses magnetic forces to
accelerate payloads. Typically two parallel conducting rails are bridged by a
plasma arc. The plasma is accelerated downJthe gun by the arrangement of
currents and fields. Given suitable power supplies, it can be considered for
earth launch systems at lower accelerations than those proposed for weapon
systems.J J
Status:
This device was under intensive development for the Strategic Defense
Initiative. A large gun was built at Eglin AFB in Florida and used a bank of
thousands of car batteries wired in parallel as a power supply. Prototype
railguns achieved high velocities, but the high currents produced rail
erosion.
Variations:
References:
[72] Robinson, C. A. "Defense Department Developing Orbital Guns", Aviation
Week and Space Technology, v 121 no 12 pp 69-70, 1984.J J
[73]Bauer, D. P. et al "Application of Electromagnetic Accelerators to Space
Propulsion" IEEE Trans. Magnetics vol MAG-18 no 1 pp 170-5, Jan. 1982.
23 Coilgun
Alternate Names: Mass Driver Launcher
Type:
Description:
Series of coils forming gun react with coil(s) on projectile
magnetically, producing thrust. Popularly known as a 'mass
driver', this concept uses magnetic attraction between two current
carrying coils to accelerate a projectile. The concept has been
developed in connection with launching lunar materials for space
manufacturing.J Accelerator designs with high efficiency (>90%) and
high muzzle velocitiesJ (>8 km/s) have been proposed. This
potentially leads to a transportationJ system whose operating costs
consist mostly of electricity, or $0.28/lb.J Laboratory versions of
electromagnetic accelerators have reachedJ1800 gravities acceleration.
Accelerations in the range of 50-100 gravities are sufficient for
cargo launch from the surface of the earth.
Status:
Variations:
References:
[74] Nagatomo, Makoto; Kyotani, Yoshihiro "Feasibility Study on Linear-Motor-
Assisted Take-Off (LMATO) Of Winged Launch Vehicle", Acta Astronautica, v 15
no 11 pp 851-857, 1987.
[75] Kolm, H.; Mongeau, P. "Alternative Launching Medium", IEEE Spectrum, v
19 no 4 pp 30-36, 1982.
[76] Kolm, H. "An Electromagnetic 'Slingshot' for Space Propulsion",
Spaceworld pp 9-14, Feb. 1978.
D.3 Combustion Engines
D.3a Air-Breathing Engines
Concepts 24 through 27 all involve using a planet's (usually the Earth's)
atmosphere as a supply of oxygen to support combustion with a fuel carried
on the vehicle. It should be noted that some vehicle concepts (such as the
National Aerospaceplane (NASP) would integrate more than one engine
concept in a single engine. For example, most NASP configurations would
have ramjet and scramjet propulsion combined in the same engine.
24 Fanjet
Alternate Names:
Type:
Description:
The fanjet is the standard type of jet engine found on passenger
aircraft and military aircraft. The original form of the engine, the
turbo-jet, has a series of turbine compressor stages to compress the
incoming air flow. This is followed by a combustor where fuel is
added and burned, creating a hot gas. The gas is then expanded
through a turbine which is connected by a shaft to the compressor.
The expanded gas emerges at high velocity from the back of the engine.
The modern fanjet adds a fan which is also driven by the turbine. All of the
airflow goes through the fan, but only a part goes into the compressor. The
air which does not go into the compressor is said to have 'bypassed' the
compressor. The 'bypass ratio' is the ratio of bypass air to combustor air.
Generally higher bypass ratio engines are more fuel efficient (in units of
thrust divided by fuel consumption rate). Also in general, engines that
operate at higher speeds are designed with lower bypass ratios.
Typical modern performance values are engine thrust-to weight ratios
(T/W) of 6:1 for large subsonic engines, trending towards about 10:1
for high performance military jets. Fuel efficiency is measured in
units of thrust divided by mass flow rate. In English units this is
pounds divided by pounds per second, or just seconds, and is termed
'specific impulse'. In SI units this is Newtons per kilogram per
second, which has the units of meters per second. In some propulsion
systems, such as chemical rockets, the SI unit corresponds to the
actual exhaust jet velocity. In the case of air- breathing propulsion
it is not, the velocity result is just an indicator of engine
efficiency. In English units the performance of subsonic engines is
about 10,000 seconds, trending to about 7000 seconds for supersonic
military engines. Fanjets and turbojets operate up to about 3.5 times
the speed of sound (M=3.5).
Status:
In common use on aircraft for aircraft propulsion. The B-52 bomber has
been used to carry the Pegasus three stage solid rocket to 35,000 ft
altitude. The B-52 uses 8 fanjet type engines for propulsion. Numerous
paper studies have been made of using aircraft as carriers for rocket stages.
Variations:
References:
25 Turbo-Ramjet
Alternate Names:
Type:
Description:
A fan compresses incoming air stream, which is then mixedJwith fuel,
burned and exhausted. Compressor is driven by gas generator/turbine. In a
fanjet, the incoming air is compressed and heated by the compressor stages,
then mixed with fuel and run through the turbine stages. At higher
velocities the air gets hotter in compression since it has a higher incoming
kinetic energy. This leads to a higher turbine temperature. Eventually a
turbine temperature limit is reached based on the material used, which sets a
limit to the speed of the engine. In the turbo-ramjet the compressor is
driven by a gas generator/turbine set which use on-board propellant for their
operation. Since the gas generator is independant of the flight speed, it can
operate over a wider range of Mach numbers than the fanjet ( to Mach 6 vs.
to Mach 3)
Status:
Variations:
References:
26 Ramjet
Alternate Names:
Type:
Description:
Incoming air stream is accelerated to subsonic relativeJto engine,
mixed with fuel, then exhausted. The incoming air is moving at the
vehicle velocity entering the engine. After burning the fuel, the air
is hotter and can expand to a higher velocity out the nozzle. This
sets up a pressure difference that leaves a net thrust. Ramjets
cannot operate at zero speed, but they can reach somewhat higher limits
than an engine with rotating machinery (range Mach 0.5 to about Mach 8).
Status:
Variations:
References:
27 Scramjet
Alternate Names:
Type:
Description:
Incoming air stream is compressed by shock waves, mixedJwith fuel, and
expanded against engine or vehicle. Tha airstream remains supersonic
relative to the vehicle. The forward thrust is produced by expanding the
exhaust against a nozzle shape. Even though the gas is moving
supersonically relative to the vehicle, the sidewise expansion can act on the
vehicle if the slope of the nozzle is low enough. Thus the vehicle can fly
faster than the exahust gas moves. Scramjets may provide useful thrust up
to about Mach 15, or 60% of orbital speed.
Status:
Variations:
References:
28 Inverted Scramjet
Alternate Names: Buoyant Scramjet
Type:
Description: Series of balloons floated in atmosphere through which
projectile flies. Projectile carries oxygen and flies through hydrogen
(oxygen is much denser, so cross section is reduced.
Status:
Variations:
References:
29 Laser-Thermal Jet
Alternate Names:
Type:
Description: Laser is focussed and absorbed in heat exchanger, or laser-
sustainedJ plasma.
Status:
Variations:
References:
[78] Myrabo, L. N. "Concept for Light-Powered Flight", AIAA paper number 82-
1214 presented at AIAA/SAE/ASME 18th Joint Propulsion Conference,
Cleveland, Ohio, 21-23 June 1982.
D.3b Internally Fuelled Engines
30 Solid Rocket
Alternate Names:
Type:
Description: A solid rocket consists of a high-strength casing, a
nozzle, and a solid propellant grain which burns at a pre-designed
rate. The grain is a mixture of materials containing both fuel and
oxidizer, so combustion can proceed without any external action once
it is ignited. Modern solid propellants have a formulation close to
the following: About 15% by weight organic fuel, usually a type of
rubber, about 20% by weight aluminum powder (which acts as a metallic
fuel), and about 65% ammonium perchlorate (NH3ClO4), which is the oxidizer.
About 1-2% epoxy is added to the powders to hold them together. The epoxy,
being an organic material, is also part of the fuel.
Status:
Variations:
References:
31 Hybrid Rocket
Alternate Names:
Type:
Description: The hybrid rocket consists of a solid fuel grain and a liquid
oxidizer. One combination is rubber for the fuel and liquid oxygen for the
oxidizer. The fuel is in the form of a hollow cylinder or perforated block.
The oxidizer is sprayed onto the fuel and the material is ignited. By not
being self-supporting in combustion, the fuel part can be treated as non-
hazardous whn being made and shipped. Only when on the launch pad and
the oxidizer tank is filled is there a hazardous combination. With only a
single liquid to handle, the harware is relatively simple in design.
Status:
Variations:
References:
32 Liquid Rocket
Alternate Names:
Type:
Description: Mixture of fuel and oxidizer are burned in combustion
chamber which leads to a converging-diverging nozzle. The flow becomes
sonic at the narrow part of the nozzle, then continues to accelerate in the
diverging part of the nozzle. This is the most common form of launch
propulsion used to date to put things in Earth orbit. A variety of propellant
combinations have been used, including mono- bi-, and even tri-propellant
combinations.
Status:
Variations: Number propellant variants by oxidizer/fuel letters
Oxidizer Variants
Formula Mol. Wt.
a Oxygen O2 32
b Hydrogen Peroxide O2H2 34
c Fluorine F2 36
d Nitrogen Tetroxide N4O4 92
Fuel Variants
a Hydrogen H2 2
b Methane CH4 16
Pump-fed Variant
Pressure-fed Variant
References:
[42] Cooper, Larry P. "Status of Advanced Orbital Transfer Propulsion", Space
Technology (Oxford), v 7 no 3 pp 205-16, 1987.J J
[43] Godai, Tomifumi "H-II Rocket: New Japanese Launch VehicleJ in the 1990s",
Endeavour , v 11 no 3 pp 116-21, 1987.J J
[44] Wilhite, A. W. "Advanced Rocket Propulsion Technology Assessment for
Future Space Transportation", Journal of Spacecraft and Rockets, v 19 no 4 pp
314-19, 1982.
33 Gaseous Thruster
Alternate Names:
Type:
Description: The propellant is introduced in gas form to the chamber. It
may be a mono-propellant (a single gas) or a bi-propellant combination.
Status:
Variations:
References:
34 Mechanically Augmented Thruster
Alternate Names:
Type:
Description: Velocity of exaust gases is increased by placing thrusters on
end of rotating arm. Adds 200-300 sec to specific impulse based on
structual material capabilities.
Status:
Variations:
References:
D.4 Thermal Engines
35 Electric-Rail Rocket
Alternate Names:
Type:
Description: High voltage electricity supplied by rails is shorted through
tungsten heat exchanger, which heats hydrogen carried by vehicle flying
between rails.
Status:
Variations:
References:
[71] Wilbur, P. J.; Mitchell, C. E.; Shaw, B. D. "Electrothermal
Ramjet", AIAA paper number 82-1216 presented at AIAA/SAE/ASME 18th
Joint Propulsion Conference, Cleveland, OH, 21-23 June 1982.J
36 Resistojet
Alternate Names:
Type:
Description: Sunlight generates electricity, which is used to heat gas
passed over or through a heating element.J J
Status:
Variations:
References: J
[113] Louviere, Allen J. et al "Water-Propellant Resistojets for Man-Tended
Platforms", NASA Technical Memorandum 100110, 1987.J
37 Solar-Thermal
Alternate Names:
Type:
Description: Sunlight is concentrated by a reflector or lens, then heats an
absorber. The absorber transfers heat to a working fluid, usually hydrogen.
The hydrogen is then expanded through a nozzle.
Status:
Variations:
References:
[88] Gartrell, C. F. "Future Solar Orbital Transfer Vehicle Concept", IEEE
Transactions on Aerospace Electronic Systems, vol AES-19 no 5 pp 704-10,
1983.
38 Laser-Thermal
38a Chamber Absorbtion
Alternate Names:
Type:
Description: J
Beam is passed through window in rocket engine. It is then absorbed by a
heat exchanger or is focussed to create laser-sustained plasma. Hot gas is
then expelled through nozzle. By using an energy source external to the
propellant, specific impulse increases of 100% can be achieved by using
hydrogen rather than oxygen/hydrogen.J One method of doing this is with a
large, ground-based laser to heat the hydrogen. This concept is applicable
from the ground to orbital velocity, and may be used in conjunction with
another concept. Use of laser propulsion only in an upper stage would
allow smaller lasersJthan are required for a first stage laser rocket, hence a
laser upper stage has nearer term technical viability than a first stage.J J
Status:
Variations:
References:
[79] Abe, T.; Shimada, T. "Laser Assisted Propulsion System Experiment on
Space Flyer Unit", 38th International Astronautical Federation Conference paper
number IAF-87-298, 1987.J J
[80] Abe, T.; Kuriki, K. "Laser Propulsion Test Onboard Space Station", Space
Solar Power Review vol 5 no 2 pp 121-5, 1985.J J
[81] Jones, L. W.; Keefer, D. R. "NASA's Laser Propulsion Project",
Astronautics and Aeronautics, v 20 no 9 pp 66-73, 1982.
38b External Ablation
Alternate Names: Laser Detonation-Wave Engine J
Type:
Description:
Propellant is a solid block with a flat bottom. First laser pulse evaporates a
layer of propellant. Second, larger, pulse creates plasma detonation wave,
which shocks and heats the propellant layer. Layer expands against base of
solid block.J J
Status:
Variations:
References:
[82] Kare, J.T. "SDIO/DARPA Workshop on Laser Propulsion, Volume 1:
Executive Summary" Lawrence Livermore National Laboratory report number
DE87-003254, 1987.
39 Microwave Thermal J
Alternate Names:
Type:
Description:
Microwaves are absorbed by engine, which becomes hot.J Hydrogen is
flowed through engine, gets hot, and is then exhausted.J A large phased
microwave array on the ground can focus onto a rocket-sized area over a
range of hundreds of kilometers. Given a way to couple the microwave
energy to a working fluid such as hydrogen, this type of propulsion could
provide significant launch vehicle velocities.J High power microwave
amplifiers exist in a variety of forms with efficiencies up to 75% and power
levels up to one megawatt. This concept uses direct heating of the engine
structure, which acts as a heat exchanger to heat the working fluid.
Example: 10 meter diameter receiver, 5 cm wavelength, 1 km phased array,
range = 200 km.
Status:
Variations:
References:
40 Solid Core Nuclear
Alternate Names:
Type:
Description:
Hydrogen is heated by flowing through nuclear reactor,J then exhausted in
rocket nozzle. Although the nuclear rocket program was stopped a number
of years ago, more recent work at Brookhaven National Laboratories on
fluidized particle bed reactors warrants their consideration for launch
vehicles. The small particle size (.3 mm) allows high heat transfer rates to
the working fluid, hydrogen, and hence potentially high thrust to weight
ratios.J J
Status:
Variations:
References:
[49] Thomas, Ulrich "Nuclear Ferry - Cislunar Space Transportation Option
of the Future", Space Technology (Oxford) v 7 no 3 pp 227-234,J 1987.J J
[50] Holman, R.R.; Pierce, B. L. "Development of NERVA reactor for Space
Nuclear Propulsion", presented at AIAA/ASME/SAE/ASEE 22nd Joint
Propulsion Conference, Huntsville, Alabama, 16-18 Jun 1986, AIAA paper
number 86-1582, 1986.J J
[51] Thom, K. et al "Physics and Potentials of Fissioning PlasmasJ for Space
Power and Propulsion", Acta Astronautica vol 3 no 7-8 pp 505-16, Jul. -Aug.
1976.J J
[46] DiStefano, E. "Space Nuclear Propulsion - Future Applications and
Technology", 2nd Symposium on Space Nuclear Power Systems, Albequerque,
New Mexico, 14 January 1985, pp 331-342, 1987.J J
41 Liquid Core Nuclear
Alternate Names:
Type:
Description: In order to attain higher performance than a solid core
rocket, the reactor core is raised to a high enough temperature to become
liquid. Hydrogen is bubbled through the liquid, then exhausted out a
nozzle.
Status:
Variations:
References:
42 Gas Core Nuclear
Alternate Names:
Type:
Description: The reactor core is hot enough that the core is gasseous in
form. The hydrogen flow is seeded with an absorbent material to directly
absorb the thermal radiation from the core. The core is kept from leaking
out the nozzle by a transparent container (nucear light bulb), a flow vortex,
which uses the density difference between uranium and hydrogen, or
magnetic separation, which uses the ionization difference between the
uranium and the hydrogen.
Status:
Variations:
References:
43 Muon-Catalyzed Fusion
Alternate Names:
Type:
Description:
A beam of muons is directed at a deuterium/tritiumJ mixture, where the
muons catalyze mutiple fusion reactions. The heatedJ gas powers an
electric generator to power an ion or neutral particleJ beam thruster.
Status:
Variations:
References:
D.5 Bulk Matter Engines
44 Rotary Flinger
Alternate Names:
Type:
Description: A one or two stage rotary mechanism mechanically
accelerates a small amount of reaction mass, then releases it. In the two
stage version, top speeds of 6 km/s are possible.
Status:
Variations:
References:
45 Coilgun Engine
Alternate Names: Mass Driver Reaction Engine
Type:
Description: A carrier, or bucket, is accelerated by interaction ofJ
magnetic fields from 'driver' coils. The carrier holds a reaction mass,
which is released. The bucket is slowed down and reused.
Status:
Variations:
References:
46 Railgun Engine
Alternate Names:
Type:
Description:The interaction of the fields in current carrying railsJ and a
plasma short circuit of the rails accelerates the plasma, andJ anything in
front of it.J
Status:
Variations:
References:
D.6 Ion and Plasma Engines
47 Arc Jet
Alternate Names:
Type:
Description:
Sunlight is converted to electricity by a photovoltaic array. The
electricity is arced through a propellant stream, heating it. The
propellant is then expanded through a nozzle.J J J
Status:
Variations:
References:
[89] Hardy, Terry L.; Curran, Francis M. "Low Power DC Arcjet Operation with
Hydrogen/Nitrogen/Ammoinia Mixtures", NASA TechnicalJ Memorandum
89876, 1987.
[90] Stone, James R.; Huston, Edward S. "NASA/USAF Arcjet Research and
Technology Program", NASA Technical Memorandum 100112, 1987.J J
[91] Kagaya, Y. et al "Quasi-steady MPD Arc-jet for Space Propulsion",J
Symposium for Space Technology and Science, Tokyo, Japan, 19 May 1986, pp
145-154, 1986.J J
[92] Manago, Masata et al "Fast Acting Valve for MPD Arcjet",J IHI Engineering
Review, v 19 no 2 pp 99-100, April 1986.J J
[93] Pivirotto, T. J.; King, D. Q. "Thermal Arcjet TechnologyJ for Space
Propulsion", Chemical Propulsion Information Agency, Laurel, Maryland, 1985.
48 Electrostatic Ion
Alternate Names:
Type:
Description:
Status:
Variations:
References:
[53] Rawlin, Vincent K; Patterson, Michael J. "High Power Ion Thruster
Performance", NASA Technical Memorandum 100127, 1987.J J
48a Solar-Electric Ion
Sunlight is converted to electricity by a photovoltaic array. The
electricity is used to ionize and electrostatically accelerate the
propellant.J J
[94] Mitterauer, J. "Liquid Metal Ion Sources as Thrusters forJ
Electric Space Propulsion", J. Phys. Colloq. (France) volJ 48, no C-6,
pp 171-6, Nov. 1987.J J
[95] Mitterauer, J. "Field Emission Electric Propulsion - EmissionJ
Site Distribution of Slit Emitters", IEEE Trans. on Plasma Sci.J vol
PS-15, pp 593-8, Oct. 1987.J J
[96] Stuhlinger, E. et al "Solar-Electric Propulsion for a Comet Nucleus Sample
Return Mission" presented at 38th Congress of the InternationalJAstronautical
Federation, Brighton, England, 10 Ocotober 1987.J J
[97] Nakamura, Y.; Kuricki, K. "Electric Propulsion Test Onboard the Space
Station", Space Solar Power Review vol 5 no 2J pp 213-9, 1985.J J
[98] Voulelikas, G. D. "Electric Propulsion: A Review of Future Space
Propulsion Technology"J Communications Research Centre, Ottawa,
Ontario, report numberJ CRC-396, October 1985.J J
[99] Bartoli, C. et al "A Liquid Caesium Field Ion Source for Space
Propulsion", J. Phys. D vol 17 no 12 pp 2473-83, 14J Dec. 1984.J J
[100] Imai, R.; Kitamura, S. "Space Operation of Engineering Test
Satellite -III Ion Engine", Proceedings of JSASS/AIAA/DGLR 17th Intl.J
Electric Propulsion Conf. pp 103-8, 1984.J J
[101] Jones, R. M.; Poeschel, R. L. "Primary Space Propulsion for 1995-2000 -
Electrostatic Technology Applications" AIAA/SAE/ASME 20th Joint Propulsion
Conference, AIAA paper number 84-1450, 1984.J J
[102] Bartoli, C. et al "Recent Developments in High Current LiquidJ Metal Ion
Sources for Space Propulsion", Vacuum vol 34 noJ 1-2 pp 43-6, Jan. -Feb.
1984.J J
[103] Brophy, J. R.; Wilbur, P. J. "Recent Developments in IonJ Sources for
Space Propulsion", Proceedings of the Intl. Ion Engineering Congress vol 1 pp
411-22, 1983.J [104] Anon. "Ion Propulsion Engine Tests Scheduled", Aviation
Week and Space Technology, v 116 no 26 pp 144-5, 1982.J J
[105] James, E.; Ramsey, W., Sr.; Steiner, G. "Developing a Scaleable Inert Gas
Ion Thruster", AIAA paper number 82-1275 presented at AIAA/SAE/ASME 18th
Joint Propulsion Conference, Cleveland, OH, 21-23 June 1982.J
[106] Zafran, S. et al "Aerospace Highlights 1982: Electric
Propulsion",JAstronautics and Aeronautics, v 20 no 12 pp 71-72, 1982.J J
[107] Clark, K. E.; Kaufman, H. B. "Aerospace Highlights 1981: Electric
Propulsion", Astronautics and Aeronautics, v 19 no 12 pp 58-59, 1981.J J
[108] Kaufman, H. R. "Performance of Large Inert-Gas Thrusters",J AIAA paper
number 81-0720 presented at 15th International Electric Propulsion Conference,
Las Vegas, Nevada, 21-23 April 1981.J J
[109] Byers, D. C.; Rawlin, V. K. "Critical Elements of Electron-BombardmenJ t
Propulsion for Large Space Systems", J. Spacecraft and RocketsJ vol 14 no 11
pp 648-54, Nov. 1977.J J
[110] Mutin, J.; Tatry, B. "Electric Propulsion in the Field ofJ Space", Acta
Electron. (France) vol 17 no 4 pp 357-70, Oct.J 1974 (in French).
48b Thermoelectric Ion
Radioactive isotope decay produces heat. Heat is converted to electricity by
semiconductors. Electricity ionizes and accelerates atoms in engine.J J
48c Laser-Electric Ion
Laser tuned to optimum absorption wavelength of photovoltaicJ cells. Cells
convert laser light to electricity, which is used toJ power ion engine. Ion
engine accelerates ionized propellants electrostaticallyJ .J J
[D] Maeno, K. "Advanced Scheme of CO2 Laser for Space Propulsion", Space
Solar Power Review vol 5 no 2 pp 207-11, 1985.J
48d Microwave-Electric Ion
J
A microwave receiving antenna (rectenna) on spacecraft converts
microwaves to electricity. Electricity is used to ionize and accelerate
atoms.J J
[D] Nordley, G. D.; Brown, W. C. "Space Based Nuclear-Microwave Electric
Propulsion", 3rd Symposium on Space Nuclear Power Systems,J Albuquerque,
New Mexico, 13 January 1986, pp 383-95, 1987.
48e Nuclear-Electric Ion
J
Nuclear reactor generates heat, which is converted to electricity in
thermoelectric or turbine/generator cycles. Electricity is used to ionize
propellant and accelerate it by electrostatic voltage.J J J J
[1] Cutler, A. H. "Power Demands for Space Resource Utilization",J Space
Nuclear Power Systems 1986 pp 25-42.J J
[2] Buden, D.; Garrison, P. W. "Space Nuclear Power Systems andJ the Design
of the Nuclear Electric Propulsion OTV", presented at AIAA/SAE/ASME 20th
Joint Propulsion Conference, AIAA paper number 84-1447, 1984.
[3] Powell, J. R.; Boots, T. E. "Integrated Nuclear Propulsion/PrimeJ Power
Systems", AIAA paper number 82-1215 presented at AIAA/SAE/ASMEJ 18th
Joint Propulsion Conference, Cleveland, Ohio, 21-23 June 1982.J J
[4] Powell, J. R.; Botts, T. E.; Myrabo, L. N. "Annular Bed Nuclear
Power Source for Electric Thrusters", AIAA paper number 82-1278
presented at AIAA/SAE/ ASME 18th Joint Propulsion Conference,
Cleveland, Ohio, 21-23 June 1982.J J
[5] Ray, P. K. "Solar Electric versus Nuclear Electric Propulsion in Geocentric
Space", Trans. Am. Nucl. Soc. vol 39 pp 358-9, Nov.-Dec. 1981.J J
[6] Hsieh, T. M.; Phillips, W. M. "An Improved Thermionic Power Conversion
System for Space Propulsion", Proceedings of the 13th Intersociety Energy
Conversion Engineering Conference pp 1917-1923, 1978.
[7] Reichel, R. H. "The Air-Scooping Nuclear-Electric Propulsion Concept for
Advanced Orbital Space Transportation Missions", J. British Interplanetary Soc.
vol 31 no 2 pp 62-6, Feb. 1978.
49 Electron Beam Heated Plasma
Alternate Names:
Type:
Description: A high voltage (hundreds of keV) electron beam is injected
axially into a propellant flow. The electron beam heats the flow to plasma
temperatures, which produces high specific impulse. Cool gas is injected
along the chamber walls to provide film cooling and protect the chamber
from the very high temperature plasma.
Status:
Variations:
References:
50 Microwave Heated Plasma
Alternate Names: Electron-Cyclotron Absorption Rocket
Type:
Description:J Partially ionized gas directly absorbs microwaves,
becomingJhot, then expands through rocket nozzle.
Status:
Variations:
References:
51 Fusion Heated Plasma
Alternate Names:
Type:
Description: Exhaust of pure fusion rocket is a thin, extremely hot
plasma.J If higher thrust is needed, hydrogen can be mixed with plasma.
This increases thrust at the expense of performance.J
Status:
Variations:
References:
51a Reactor leakage mixed
51b Plasma Kernal Mixed
52 Antimatter-Heated Plasma J
J J Reaction : Where higher thrust is required, at a sacrifice in
performance,J hydrogen can be heated by the reaction in concept 20.
D.7 High Energy Particles
D.7a Particle Rockets
53 Pulsed Fission Nuclear
Alternate Names: Orion
Type:
Description: A series of small atomic bombs yield debris/particles
which pushes against plate/shock absorber arrangement. The shock
absorber evens out the explosion pulses to an even acceleration for the
vehicle.
Status:
Variations:
References:
54 Microfusion
Alternate Names:
Type:
Description: A conventional atomic bomb requires a certain
minimum size to operate with reasonable efficiency (a few kilotons).
In the microfusion approach, a fuel pellet consists of a fusion core
material (deuterium/tritium) surrounded by a fission shell (uranium
235). This is similar to the arrangement of a fusion atomic bomb.
Instead of chemical explosives, which are what trigger a fusion bomb,
a set of lasers or a heavy ion beam are used to compress and set off
the fission shell, which in turn sets off the fusion core. A laser or
ion compression can get higher compressions than a chemical explosion,
thus can set off smaller pellets. It is easier to set off a fission
shell than directly causing the fusion core to ignite (which is the
goal of the inertial fusion program). If explosions in the ton range
rather than kiloton range can be achieved, it will produce a more
useful vehicle than the pulsed fission concept in the previous item.
Status:
Variations:
References:
55 Alpha Particle
Alternate Names:
Type:
Description:
Radioactive element coats one side of thin sheet whichJis capable of
absorbing alpha particles. Particles emitted into sheetJare absorbed,
particles emitted in opposite direction escape, providingJnet thrust.
Status:
Variations:
References:
56 Fission Fragment
Alternate Names:
Type:
Description: Thin wires containing fissionable material are at the
heart of this concept. Thin wires are used to allow the nuclear
fragments from the fission to escape. They are directed by
electrostatic or electromagnetic fields to mostly go out the back end
of the thruster. The performance is very high because of the high
speed of the fragments.
Status:
Variations:
References:
57 Fusion Particle
Alternate Names:
Type:
Description: Various thermonuclear fusion reactors have been proposed.
The results of a fusion reaction are high energy particles which can, in
priniple, be harnessed for propulsion.
Status:
Variations:
57a Magnetic Confinement
Plasma in chamber similar to fusion power reactor is
intentionallyJleaked to magnetic nozzle.
References:
[D] Freeman, M. "Two Days to Mars with Fusion Propulsion", 21st Century
Science and Technology, vol 1, pp 26-31, Mar.-Apr. 1988.J J
[D] Kammash, T.; Galbraith, D. L. "A Fusion-Driven Rocket Propulsion
Scheme for Space Exploration", Trans. Am. Nucl. Soc. vol 54 pp 118-9, 1987.J
J
[D] Mitchell, H. M.; Cooper, R. F.; Verga, R. L. "Controlled
Fusion for Space Propulsion. Report for April 1961-June 1962", US Air
Force report number AD- 408118/8/XAB, April, 1963.J
57b Inertial Confinement
Fuel pellet is heated and compressed by lasers, electronJ beam, or ion
beam. After fusing, the resulting plasma is directedJ by a magnetic
nozzle.J
References:
[Dn] Kammash, T.; Galbraith, D. L. "A Fusion Reactor for Space
Applications", Fusion Technology, v. 12 no. 1 pp 11-21, July 1987.J J
[Dn] Orth, C. D. et al "Interplanetary Propulsion using Inertial
Fusion", report number UCRL--95275-Rev. 1: 4th Symposium on Space
Nuclear Power Systems, Albequerque, New Mexico, 12 January 1987.
57c Electrostatic Confinement
The fusion fuel is confined by a spherical potential well of order 100
kV. When the fuel reacts, the particles are ejected with energy of
order 2 MeV, so escape the potential well. The potential well is at
the focus of a paraboloidal shell, which reflects the fusion particles
to the rear in a narrow beam (20-30 degree width).
References:
57d Plasma Mantle Confinement
The fusion fuel is contained in a toroidal/poloidal current pattern,
similar to a Tokamak except all the currents are in the plasma. The
current pattern is surrounded by a plasma sheath which isolates the
fuel from a surrounding working fluid. The fluid provides mechanical
compression, which heats the fuel to fusion ignition. After the fuel
burn is completed, the energy generated heats the working fluid to
high temperature, which then goes out a nozzle producing thrust.
References:
[ See papers on 'Plasmak' fusion device in file 'Space.Propulsion'. ]
58 Neutral Particle Beam Thruster
Alternate Names:
Type:
Description: J A high energy (order 50 MeV) particle accelerator generates
a proton beam. This beam is neutralized (turned into atoms), then ejected.
The exhaust is moving at a substantial fraction of the speed of light, so
performance is very high. This type of machine was explored under the
SDI program as a way of destroying missiles (with the beam).
Status:
Variations:
References:
59 Antimatter Annihilation
Alternate Names:
Type:
Description: J Protons and antiprotons annihilate, producing pions, then
muons, then gamma rays. The charged particles can be acted upon by a
magnetic nozzle. Antimatter provides the highest theoretical energy fuel
(100% matter to energy conversion), although the overhead involved with
storing antimatter may reduce the practical efficiency to a level comparable
to other propulsion methods.J
Status:
Variations:
References:
D.7b External Particle Interaction
60 Magsail
Alternate Names:
Type:
Description: The magsail operates by placing a large superconducting
loop in the solar wind stream. The current loop produces a magnetic field
that deflects the solar wind, producing a reaction force.
Status:
Variations:
References:
61 External Particle Beam
Alternate Names:
Type:
Description: A fixed particle beam source aims it at a target vehicle. The
particles are absorbed or reflected generating thrust at the vehicle.
Status:
Variations:
References:
62 Interstellar Ramjet
Alternate Names:
Type:
Description: Compressing and fusing interstellar hydrogen for
propulsion. Because of the low density of the interstellar medium, an
extraordinarily large scoop is required to get any useful thrust. Performance
is limited by the exhaust velocity of the fusion reaction to a few percent of
the speed of light.
Status:
Variations:
References:
63 Interstellar Scramjet
Alternate Names:
Type:
Description: Similar to the interstellar ramjet, the interstellar medium is
compressed to fusion density and temperature. In this concept it is only
compressed laterally, then re-expanded against a nozzle. Incredible vehicle
sizes and lengths are required to reach fusion conditions, but speed may
reach a substantial fraction of the speed of light.
Status:
Variations:
References:
D.8 Photon Engines
D.8a Photon Sails
64 Solar Sail
Alternate Names: Lightsails
Type:
Description: J J Sunlight reflecting off a large area sail
produces force because momentum of photons is reversed by refelection.
Force is (1+r)(E/c) for normal reflection, where r is the
reflectivity of the sail, E is the incident power, and c is the speed
of light. At the distance of the Earth from the Sun, the incident
power is 1370 MW per square kilometer. This produces about 8
Newtons/square kilometer for high-reflectivity sails. J J
Status:
Variations:
References:
[Dn] Marchal, C. "Solar Sails and the ARSAT Satellite - Scientific
Applications and Techniques", L'Aeronautique et L'Astronautique, no
127, pp 53-7, 1987.
65 Laser Lightsail
Alternate Names:
Type:
Description: Laser photons are reflected off sail material. Reflection of
photons reverses their momentum vectors' component which is normal to
the sail. By conservation law, the sail gains momentum. Laser sails can
have higher performance than solar sails because the laser beam intensity is
not limited like the brightness of the sun.
Status:
Variations:
References:
66 Microwave Sail
Alternate Names: Starwisp
Type:
Description: J
Microwaves are reflected off very thin, open mesh. Momentum change of
photons bouncing off of mesh provides thrust. Because an open mesh of
thin wires can have a very low weight, in theory this propulsion method can
give high accelerations.J
Status:
Variations:
References:
D.8b Photon Rockets
67 Thermal Photon Reflector
Alternate Names:
Type:
Description: A heat generating device, such as a nuclear reactor, is at the
focus of a paraboloidal reflector. The thermal photons are focussed into a
near parallel beam, which propells the vehicle. Another high-energy source
is a matter-antimatter reaction, which is absorbed by a blanket of heavy
metals and converted to heat.
Status:
Variations:
References:
68 Quantum Black Hole Generator
Alternate Names:
Type:
Description: In theory, a quantum black hole will emit particles as if it
were a black body of a certain temperature. If new matter is added to the
black hole at a rate sufficient to offset the emission losses, effectively 100%
conversion of matter to energy can be achieved. Black holes, quantum or
otherwise, are very massive, so the utility of such for propulsion is
questionable for anything smaller than an asteroid sized spaceship.
Status:
Variations:
References:
69 Gamma Ray Thruster
Alternate Names:
Type:
Description:
Gamma rays produced by antimatter annihilation behind vehicle can be
absorbed by a thick layer of heavy metals. Momentum of gamma ray
photons produces thrust.
Status:
Variations:
References:
D.9 External Interactions
70 Ionospheric Current Loop
Alternate Names: Electrodynamic Engine
Type:
Description: A current-carrying wire in a planetary magnetic field feels an
IxB force. The current loop is closed through an ionosphere. The wire
accelerates in one direction (pulling a vehicle along), and the ionosphere
accelerates in the other direction. Per unit of power input a current loop
thruster produces more thrust than an ion engine. No propellant is
consumed directly, although some material is consumed to produce a
plasma that enables good electrical contact with the ionosphere. Effectively
this gives a specific impulse in the 25,000 range.
Status:
Variations:
References:
[Dn] Belcher, J. W. "The Jupiter-Io Connection: an Alfven Engine in Space",
Science vol 238 no 4824 pp 170-6, 9 Oct 1987.
71 Gravity Assist
Alternate Names: Planetary Flyby, Celestial Billiards
Type:
Description: Momentum exchange between planetary body and
vehicle allow changing direction, and velocity in other reference frames.
Status:
Variations:
References:
72 Dumb-Waiter
Alternate Names:
Type:
Description: Matter falling down a gravity well can be an energy source to
power payloads going up the gravity well.
Status:
Variations:
References:
73 Aerobrake
Alternate Names:
Type:
Description: Using drag against a planetary atmosphere to slow down.J
J J
Status:
Variations:
References:
74 Rheobrake
Alternate Names:
Type:
Description: Using drag against a planetary surface to slow down.
For example, imagine a rail made of cast basalt on the lunar surface.
It is laid level to the ground, and is shaped like a conventional
steel railroad rail. An arriving vehicle is in a low grazing orbit.
It aligns with the rail, just above it, then exends some clamps over
the rail. By applying clamping pressure, the vehicle can brake from
lunar orbit to a stop. Obviously the brake will be dissipating a lot
of heat, and will therefore have to be made of high temperature
material such as graphite.
Another approach is to have a 'runway' which is a smoothed area on the
lunar surface. The arriving vehicle slows down to below orbital speed, then
gravity puts it down on the runway, and friction on the bottom of the
vehicle slows it down.
Status:
Variations:
References:
Section E: Transportation-Related
Concepts
E.1 On-site resource use
75 On-site fuel extraction
Alternate Names:
Type:
Description: If you don't have to bring it with you, your mass ratio
improves.
Status:
Variations:
References:
[E1] Ramohalli, K.; Ash, R.; Dowler, W.; French, J. "Some Aspects of
Space Propulsion with Extraterrestrial Resources", Journal of
Spacecraft and Rockets v 24 no 3 pp 236-44, 1987.J J J
76 Comet consumption en-route
Alternate Names:
Type:
Description: Interstellar missions require a lot of propellant. In this
concept, several comets are intercepted by a propulsion unit that comes from
the 'mother ship'. The propulsion unit consumes part of the comet to bring
the rest of the comet up to speed, and then uses the remainder to further
accelerate the mother ship. This allows somewhat better velocities than
starting with all the fuel onboard at the start of the mission.
Status:
Variations:
References:
77 Solar Sails from FeNi Asteroid
Alternate Names:
Type:
Description: To recover large amounts of material from the
asteroids, Iron-nickel alloy can be rolled into foil, and the foil
used to make solar sails. If the material you want to extract is
steel, then it sails itself back to where you want it. If you want
some other material, you can make large amounts of sail area fairly
simply (you need the equivalent of a rolling mill - a way to heat the
material and a way to force it between two rollers to make thin
sheets. Steel is not as light as aluminum-magnesium alloy as a sail
material, and it is not as good a reflector, but it is readily
available in large quantities in asteroids and does not need a lot of
processing to make into a useable
form.
Status:
Variations:
References:
78 Structural materials
Alternate Names:
Type:
Description: A variety of structural materials can be made from local
materials in space, thus reducing the amount of material that has to be
brought from Earth. Examples include Iron-nickel from that type of
asteroid, and from meteoroid dust on the lunar surface (which only require
magnetic separation), and cast or sintered rock, using solar heating to melt
random rock into useful shapes.
Status:
Variations:
References:
79 Solar Power Stations
Alternate Names:
Type:
Description: Sunlight in space is not affected by night, clouds, or
atmospheric absorbtion. A large solar power plant can produce power, then
send it elsewhere using an efficient microwave beam. Example uses are to
deliver power to Earth from orbit, and to deliver power to a Mars lander
using the transit vehicle solar array.
Status:
Variations:
79a Planet Surface
79b Orbiting
79c Photovoltaic
79d Solar-Thermal
References:
80 Atmospheric Laser
Alternate Names:
Type:
Description: Lasing medium is the atmosphere or ionosphere of a planet
or satellite.J J
Status:
Variations:
References:
E.2 Payload Mass/Volume Minimization
81 Closed Life Support
By recycling part or all of the materials used to sustain life, the amount of
stored supplies or newly delivered supplies can be reduced. If coupled with
local extraction of life support supplies, can reduce the amount of extraction
required. Water, air, and food are the principal items that can be recycled.
82 Inflatable/Erectable Structures
For launch from a planet it may be useful to collapse a structure into a small
package. Once on location it is inflated or assembled to form the finished
object.
83 Recycling upper stages
A conventional rocket takes the final stage, along with the payload, into
orbit. By re-fueling the stage, or by converting the stage tanks and
structures to another use (such as an occupied pressurized module), some
payload weight and volume is saved.
84 Fabricators/Replicators
A general-purpose factory system can make a wide variety of products,
including copies of most or all of it's own parts. Then a small seed factory
can grow to a large production capacity with a high output product to intial
payload mass ratio.
85 Nanofax Transmitter
The energy to transmit the description of an object to another star, even at an
atom by atom level, is about a million times less than the energy to
physically move the object from one star to another. Thus, after the first
probe sets up a receiving/replication station at the other star, other objects
are more efficiently scanned, transmitted, and reconstructed at the receiving
end. Using atomic scale technology (nanotech) it may be possible to send
people this way. The subjective time to travel at the speed of light is zero.
Section F: General References
References [F1] to [F18] contain data about two or more propulsion
concepts:
[F1] Byers, David C.; Wasel, Robert A. "NASA Electric PropulsionJProgram",
NASA Technical Memorandum 89856, May 1987.
[F2] Forward, R. L. "Advanced Space Propulsion Study - Antiproton and
Beamed Power Propulsion", Final Report, 1 May 1986 - 30 Jun 1987,J Hughes
Research Laboratories, report AFAL-TR-87-070, 1987.
[F3] Forward, R. L. "Exotic Propulsion in the 21st Century", in Aerospace
Century XXI (see reference [F8]).J J
[F4] Harvego, E. A.; Sulmeisters, T. K. "A Comparison of Propulsion Systems
for Potential Space Mission Applications", ASME WinterJ Meeting, Boston,
Massachusetts, 13 December 1987, 1987.
[F5] Kerrebrock, J. L "Report of the National Commission on SpaceJ- One
Commissioner's View", in Aerospace Century XXI (seeJreference [F8]).
[F6] Korobeinikov, V. P. "On the Use of Solar Energy for the Acceleration of
Bodies to Cosmic Velocities", Acta Astronautica, v 15 no 11 p 937-40, November
1987.
[F7] Matloff, G. L. "Electric Propulsion and Interstellar Flight", 19th
International Electric Propulsion Conference, Colorado Springs, Colorado, 11
May 1987.
[F8] Morgenthaler, G. W.; Tobiska, W. K. "Aerospace Century XXI:JSpace
Flight Technologies", Proceedings of the 33rd Annual AAS InternationalJ
Conference, Boulder, Colorado, 26-29 Oct. 1986. Published as Advances in the
Astronautical Sciences, vol 64, pt 2, 1987.
[F9] Phillips, P. G.; Redd, B. "Propulsion Options for Manned
Missions to the Moon and Mars", in Aerospace Century XXI (see reference F8).
[F10] Faughnan, Barbara (ed.); Maryniak, Gregg (ed.) "Space Manufacturing 5:
Engineering with Lunar and Asteroidal Materials", proceedings of the 7th
Princeton/AIAA/SSI Conference, Princeton, New Jersey, 8-11 May 1985.
[F11] Wang, S.-Y.; Staiger P. J. "Primary Propulsion of
Electro-Thermal, Ion and Chemical Systems for Space Based Radar Orbit
Transfer", AIAA/SAE/ASME/ASEE 21st Joint Propulsion Conference, AIAA
paper number 85-1477, 1985.
[F12] Jones, R. M. "Space Supertankers: Electric Propulsion Systems for the
Transportation of Extraterrestrial Resources" AIAA/SAE/ASME 20th Joint
Propulsion Conference, AIAA paper number 84-1323, 1984.
[F13] Jones, R. M.; Kaplan, D. I.; Nock, K. T. "Electric Propulsion
Systems for Space Stations" AIAA/SAE/ASME 19th Joint Propulsion
Conference,J AIAA paper number 83-1208, 1983.
[F14] Poeschel, R. L. "Comparison of Electric Propulsion Technologies",J
AIAA paper number 82-1243 presented at AIAA/SAE/ASME 18th Joint
Propulsion Conference, Cleveland, Ohio, 21-23 June 1982.
[F15] Diesposti, R. S.; Pelouch, J. J. "Performance and
EconomicJComparison of Externally Energized vs Chemically Energized Space
Propulsion",J AIAA paper number 81-0703 presented at 15th International
Electric Propulsion Conference, Las Vegas, Nevada, 21-23 June 1981.
[F16] Kunz, K. E. "Orbit Transfer Propulsion and Large Space Systems", J.
Spacecraft and Rockets vol 17 no 6 pp 495-500, Nov.-Dec. 1980.
[F17] Parkash, D. M. "Electric Propulsion for Space Missions",
Electr. India vol 19 no 7 pp 5-15, 15 April 1979.J J
[F18] Loeb, H. W. "Electric Propulsion Technology Status and
Development Plans - European Programs (Space Vehicles)", J. Spacecraft
and Rockets , vol 11 no 12 pp 821-8, Dec. 1974.J
--
A higher intelligence, formerly from the Bubbleworld on the
far side of the Galaxy, now masquerading as a human engineer.
|
| 311.26 | Hypervelocity launcher | MTWAIN::KLAES | Keep Looking Up | Wed May 25 1994 15:11 | 36 |
| From: US4RMC::"carr#m#[email protected]" "Carr,Paul" 25-MAY-1994 09:46:48.18
To: Space Technology Discussion Group <[email protected]>
CC:
Subj: hypervelocity launcher
Interesting note from "Desgin News", dated 9 May 1994:
"A hypervelocity launcher at Sandia National Labs has accelerated a
quarter-inch diameter plate of metal to a reported record-high
velocity of 15.8 km/sec, or nearly 36,000 mph. For reference, the
researchers say, a high powered rifle bullet travels about 0.6 km/sec,
or about 1340 mph. The record speed equals the relative velocity of
two space objects colliding head-on in low-earth-orbit. This is
significant because the Sandia facility supports NASA in the design of
debris shielding materials for the space station and telecommunication
satellites. Fax Lalit Chhabildas (505) 844-0918"
Anyuone know what technology they're using? Any relation to SSI-type
mass drivers?
############################################################
Paul Carr
Martin Marietta Astro Space (usual disclaimer applies)
Princeton, NJ
"He had foreborne, hoping that others would forbear, and they had not.
He had toiled in back rooms while shallower men held the stage. They
held it still." - - - LeCarre, _Smiley's People_
############################################################
% ====== Internet headers and postmarks (see DECWRL::GATEWAY.DOC) ======
% Date: 25 May 1994 09:08:57 -0400
% From: "Carr,Paul" <carr#m#[email protected]>
% Subject: hypervelocity launcher
% To: Space Technology Discussion Group <[email protected]>
|
| 311.27 | RE 311.26 | MTWAIN::KLAES | Keep Looking Up | Tue May 31 1994 18:09 | 75 |
| From: US4RMC::"[email protected]" 26-MAY-1994 22:02:51.71
CC:
Subj: Re: Hypervelocity launcher
Paul, I'm pretty sure they're using a light gas gun driven by
a large plastic piston:
----------\ piston deforms into necked area, raising pressure
piston | | He \----------- of helium in breech to several
driven | | gas /----------- hundred kpsi, and firing projectile
by ----------/ down the barrel
conventional explosive
This is about the only concept for hypervelocity guns that even
approaches re-usability (you "just" have to machine all the extruded
plastic out of the gun barrel. The electromagnetic rail guns that get
into the 10-klick range are typically a one-shot device that must be
completely rebuilt after each firing. The RAM accelerator project
(which I did some grad work on) at last count had only reached
"several" klicks; and I'm pretty sure it didn't go to Sandia for
further development.
Ben Trueblood
[email protected]
% ====== Internet headers and postmarks (see DECWRL::GATEWAY.DOC) ======
% Date: Thu, 26 May 94 22:00:57 EDT
% Reply-To: [email protected]
% Originator: [email protected]
% Sender: [email protected]
% From: [email protected] (Ben Trueblood)
% Subject: Re: Hypervelocity launcher
% X-Listserver-Version: 6.0 -- UNIX ListServer by Anastasios Kotsikonas
% X-Comment: SSI Members email Discussion Group
From: US4RMC::"[email protected]" "MAIL-11 Daemon" 27-MAY-1994 00:46:22.82
To: [email protected]
CC:
Subj: Re: hypervelocity launcher
Finally..., a topic I have some expertise in...
>Interesting note from "Desgin News", dated 9 May 1994:
>Anyone know what technology they're using? Any relation to SSI-type mass
>drivers?
Typically 2-stage light gas guns (that use hydrogen) are used to
accelerate projectiles to ~7 km/s. I've personally done experiments at
the NASA Ames Vertical Gun Range, where we could get 3.2mm Al spheres
up to around 6.5 km/s. The problem we had at Ames beyond around ~7
km/s was photographic flash over: i.e. the photographs used to verify
the projectile velocity weren't able to 'see' the spherical
projectile. Also, the velocity we could achieve depended upon whether
or not they were braking in a new barrel.
I have also done low velocity experiments at the University of Dayton
Impact Physics Laboratory; using the powder guns, we got a 6.35 mm St.
sphere up to 2.044 km/s.
Getting back to your question, they may use some kind of EM
acceleration, a new technology light gas gun or possibly some hybrid
of the two different technologies. I haven't sat down and worked out
the theoretical velocity limit for spherical projectiles using light
gas gun technology in quite sometime. I'll have to give that more thought.
Douglas J. Buettner, M.S. Physics (Hypervelocity Intact Capture)
% ====== Internet headers and postmarks (see DECWRL::GATEWAY.DOC) ======
% From: [email protected]
% X-Mailer: America Online Mailer
% Sender: DBuettner <[email protected]>
% To: [email protected]
% Date: Fri, 27 May 94 00:25:32 EDT
% Subject: Re: hypervelocity launcher
|
| 311.28 | Canonical List Version 0.75 - Part 1 of 4 | MTWAIN::KLAES | Houston, Tranquility Base here... | Tue Jul 05 1994 15:30 | 740 |
| Article: 2391
From: [email protected] (Dani Eder)
Newsgroups: sci.space.tech
Subject: Canonical List of Space Transport Methods (1/4)
Date: 1 Jul 94 18:16:29 GMT
Organization: Boeing AI Center, Huntsville, AL
Canonical List
of
Space Transport and Engineering Methods
Version 0.75 28 Jun 1994
Dani Eder
Route 1, Box 188-2
Athens, AL 35611
[email protected]
Introduction
This document is a list of all known space transport methods and some
space engineering methods. It includes only those methods whose
underlying physical principles are understood (i.e. no warp drives as in
Star Trek). It is the product of a number of years of collecting -
and occasionally inventing - them.
I am motivated by a desire to see civilization expand into space and my
frustration by the slow pace of progress at the current time. Most current
space vehicles and projects use techniques that existed in the 1950's and
1960's. Some new ideas were developed as early as 1960, but have not
been put into used even today. From the 1970's to today many additional
ideas have been generated. Most of these have received scant attention.
By disseminating information on these ideas, I hope others will realize
the vast untapped potential contained in these ideas.
This draft (version 0.75) lists all the concepts I am aware of, with at
least a basic description of each. As you can tell by the version number,
which is less than one, this is still very much a work in progress. Later
versions of this document are intended to flesh out each method with
improved descriptions and current references. If you know of a method
which is not on this list, I would appreciate being informed of it. If
you have references or text descriptions on a concept, they would be
appreciated also.
Some related information on the basics of space transport, the forces and
energies used, and space project engineering are included. Editorial
comments and material that needs lots of editing appear in square brackets.
The document contains the following sections:
Section A: Basics of Space Transport
Section B: Propulsive Forces List
Section C: Energy Sources List
Section D: Propulsion Concepts List
Section E: Space Engineering Methods
Section F: General References
Revision History:
version date comments
0.1-0.7 <5/94 Various in house drafts
0.71 3 Jun 94 Translated from Word to ASCII and posted to
sci.space.tech
0.72 8 Jun 94 Cleaned up text, added ideas from Landis.
------------------------------------
Section A: Basics of Space Transport
------------------------------------
The traditional job of the rocket designer has been to find the best
compromise between high cost and small payload. Larger payloads can
be achieved by making a rocket last a single flight (thus using
lighter structures than ones built to last many flights), and by
dropping parts of the propulsion system (as fuel is used up less
thrust is required to maintain acceleration, so you can drop engines).
These measures are expensive (you have to replace or re-assemble
the rocket), but were necessary in the past because of the weight
of structures and the low performance of chemical rockets.
A.1 The rocket equation
Some numbers will illustrate the problem. A good chemical rocket
has an exhaust velocity (the speed of the gases coming out the nozzle)
of 4500 m/s. The velocity to reach orbit is about 9000 m/s. The
basic equation of rocketry, the "rocket equation" tells you that
the ratio of rocket mass when full of fuel to rocket mass after
burning the fuel is:
m(i) / m(f) = exp ( dV / v(e) )
Where:
m(i) = intial mass
m(f) = final mass
dV = velocity change (9000 m/s in this case)
v(e) = exhaust velocity (4500 m/s in this case)
So in our example, dV/v(e) = 2, so m(i)/m(f) = exp(2) = 7.39.
Therefore 1/7.39, or 13.5% of the initial weight is left on reaching
orbit. In the past (before 1980s), the structure would be about 15%
of the takeoff mass, so there was a negative payload (i.e. you
couldn't get to orbit), even with a throw-away structure.
The rocket equation is generally valid for any type of reaction engine
with any velocity change.
A.2 Staging
In an attempt to increase the payload fraction, staging (dropping part of
the rocket during the ascent) has been used. The vehicle is much lighter
as it burns off fuel. Less thrust, and hence fewer or smaller engines
are required in the later part of the launch. As propellant tanks are
emptied, they can be dropped off. A set of engines and tanks dropped as
a unit is called a 'stage', and they are numbered in the order they are
used and dropped (hence first stage, second stage, etc.). The drawback
to staging is that your vehicle must be re-assembled before the next
flight. This makes operating the vehicle more expensive.
To continue the example above, let us split the vehicle into two stages,
each of which provides half of the velocity to orbit. Using the rocket
equation, each stage has a ratio of initial to final mass, or mass ratio,
of exp (1) = 2.72:1. Thus after the first stage burns it's fuel,
1/2.72 = 36.8% of the initial vehicle remains. The fuel for the first
stage represents 85% of the total first stage mass. The other 15%,
the structure and engines, is 11.1% of the total vehicle mass. So
the first stage in total is 74.4% of the total vehicle. The second
stage and payload is then 25.6% of the takeoff mass.
Similarly, the second stage has the same mass ratio, and so 36.8% of
it's mass is left after it burns it's fuel. Taking 15% for the structure,
we have 21.8% of the second stage+payload for the payload alone. Thus
the payload = 21.8% of 25.6% = 5.6% of the total vehicle mass. This
is a positive figure, unlike the single stage case, which is why all
rockets so far have used more than one stage.
A.3 Structures
The non-fuel mass of a stage can be grouped into engines, tanks, and
'other'. Engines produce 40-100 times their weight in thrust. For
liftoff from the ground, you want about 1.3 times the vehicle weight
in thrust, so the engines are about 1.3-3% of the total weight. A
large tank, such as the Shuttle External Tank, can weigh 4% of the
fuel weight, but other tanks can range up to 10% of the fuel weight.
'Other' inlcudes plumbing, parachutes (if you want to use it again)
guidance systems, and such non-propulsion parts. It can range from
1% up to 10% of the total weight.
Older materials required 15% of the total weight for one-use
structures. Modern materials require about 10% of the total weight
for re-useable structures. Structures tend to get heavier at the
rate of 10% for each factor of 10 in life. So a 100-use structure
will be about 20% heavier than a one-use structure.
A.4 Orbit equations
The circular orbit velocity, v(circ), for any body can be found from:
v(circ) = sqrt ( GM/r )
Where:
G = Gravitational constant
M = Mass of body orbited
r = radius to center of body orbited
G is a univeral constant, and the mass of the Earth is essentially
constant (neglecting falling meteors and things we launch away from
Earth), so often the product G*M = K = 3.986 x 10^14 m^3/s^2 is used.
Escape velocity = sqrt ( 2GM/r ), or sqrt(2) = 1.414 times circular
orbit velocity.
A.5 Ascent Trajectories
Circular orbit velocity at the earth's surface is 7910 meter/sec. At the
equator, the Earth rotates eastward at 465 meters/sec, so in theory a
transportation system has to provide the difference, or 7445 meters/sec.
The Earth's atmosphere causes losses that add to the theoretical velocity
increment for many space transportation methods.
In the case of chemical rockets, they normally fly straight up intially,
so as to spend the least amount of time incurring aerodynamic drag. The
vertical velocity thus achieved does not contribute to the circular orbit
veloicty (since they are perpendicular), so an optimized ascent trajectory
rather quickly pitches down from vertical towards the horizontal. Just
enough climb is used to clear the atmosphere and minimize aerodynamic drag.
The rocket consumes fuel to climb vertically and to overcome drag, so it
would achieve a higher final velocity in a drag and gravity free environment.
The velocity it would achieve under these conditions is called the 'ideal
velocity'. It is this value that the propulsion system is designed to meet.
The 'real velocity' is what the rocket actually has left after the drag and
gravity effects. These are called drag losses and gee losses respectively.
A real rocket has to provide about 9000 meters/sec to reach orbit, so the
losses are about 1500 meters/sec, or a 20% penalty.
A.6 Combining Methods
There is no law that says you have to use the same method of propulsion
all the way from the ground to orbit. In fact, it makes sense to use
different methods if one does better in the atmosphere and another does
better in the later, vacuum part of the ascent.
In past rockets, this has been done by using different type of fuel
for different stages in a rocket. In the early part of the flight, air
drag is important, so a dense fuel is preferred. A dense fuel means
smaller fuel tanks, and hence less area to create drag. Thus the
Saturn V used liquid oxygen/kerosine and the Shuttle uses solid rockets
for the first stage, both being dense fuels. Both use liquid oxygen/
liquid hydrogen for the second stage. This has the highest performance
in use for a chemical rocket fuel.
The Pegasus rocket uses an aircraft to get above the bulk of the
atmosphere. A sub-sonic jet engine has about ten times the performance
of a chemical rocket, mostly because it does not have to carry oxygen
to burn.
Many, many propulsion combinations are possible in getting to Earth
orbit and beyond. A large part of space propulsion design is choosing
which methods to use and when to switch from one to another.
---------------------------------
Section B: Propulsive Forces List
---------------------------------
This section lists the forces that can be used for propulsion. The forces
can be broken into two classes. The first class is reaction force from an
expelled material. The second class are forces created by interaction with
an entity outside the vehicle.
B.1 Reaction Against Exhaust
The list of expelled materials is generally in order of velocity. The
reaction law is Force = Mass x Acceleration (F = ma). Acceleration is
change in velocity per time (dv/dt), so we can move the dt term to the
mass and re-write the reaction law as F = (dm/dt)v (Force equals mass
change per time times velocity). In this form we can see the factors
that affect propulsion performance. If we want more force (thrust), we
can either increase the mass flow rate, or increase the velocity, or some
combination. Since a rocket by definition carries its own fuel, which is
a finite quantity, to get more performance we generally want as high an
expelled velocity as possible. In the list that follows, the range of
reasonably achieved velocities is listed. Note that what we mainly use
today (combustion gas) is among the lowest in performance.
B.1a Bulk Solid 5 km/s
B.1b Heated Gas 10 km/s
B.1c Combustion Gas 5 km/s
B.1d Plasma 20 km/s
B.1e Ion 100 km/s
B.1f Atomic Particle 10,000 km/s
B.1g Photon 300,000 km/s
B.2 External Interaction
B.2a Mechanical Traction
B.2b Cable Tension
B.2c Friction
B.2d Gas Pressure
B.2e Aerodynamic Forces
B.2f Photon Reflection
B.2g Solar Wind Deflection
B.2h Magnetic Field
B.2i Gravity Field
------------------------------
Section C: Energy Sources List
------------------------------
This section lists the sources of energy that can be used for space transport.
C.1 Mechanical Sources
C.1a Compressed Gas
C.1b Potential Energy
C.1c Kinetic Energy
C.2 Chemical Sources
C.2a Fuel-Atmosphere Combustion
C.2b Fuel-Oxidizer Combustion
C.3 Thermal Sources
C.3a Heated Storage Bed
C.3b Concentrated Sunlight
C.4 Electrical Sources
C.4a Power Line
C.4b Battery Storage
C.4c Magnetic Storage
C.4d Photovoltaic Array
[C1] Anonymous "Conference Record of the Nineteenth IEEE
Photovoltaic Specialists Conference- 1987", New Orleans, Louisiana, 4-8
May 1987.
[C2] Anonymous "NASA Conference Publication 2475: Space
Photovoltaic Research and Technology 1986: High Efficiency, Space
Environment, and Array Technology", Cleveland, Ohio, 7-9 October 1986.
[C3] Chubb, Donald L. "Combination Solar Photovoltaic Heat Engine
Energy Converter", Journal of Propulsion and Power, v 3 no 4 pp 365-74,
July-August 1987.
C.4e Solar-Driven Turbine/Generator
[C4] Spielberg, J. I. "A Solar Powered Outer Space Helium Heat Engine",
Appl. Phys. Commun. vol 4 no 4 pp 279-84, 1984-1985.
C.4f Microwave Antenna Array
C.5 Beam Sources
C.5a Laser
C.5b Microwave
C.5c Neutral Particle
C.6 Nuclear Sources
C.6a Radioactive decay
[C5] Lockwood, A.; Ewell, R.; Wood, C. "Advanced High
Temperature Thermo-electrics for Space Power", Proceedings of the 16th
Intersociety Energy Conversion Engineering Conference, v 2 pp 1985-
1990, 1981.
C.6b Nuclear Fission
[C6] El Genk, M.S.; Hoover, M. D. "Space Nuclear Power Systems
1986: Proceedings of the Third Symposium", 1987.
[C7] Sovie, Ronald J. "SP-100 Advanced Technology Program",
NASA Technical Memorandum 89888, 1987.
[C8] Bloomfield, Harvey S. "Small Space Reactor Power Systems for
Unmanned Solar System Exploration Missions", NASA Technical
Memorandum 100228, December 1987.
[C9] Buden, D.; Trapp, T. J. "Space Nuclear Power Plant Technology
Development Philosophy for a Ground Engineering Phase", Proceedings
of the 20th Intersociety Energy Conversion Engineering Conference vol 1
pp 358-66, 1985.
C.6c Nuclear Fusion
[C10] Miley, G. H. et al "Advanced Fusion Power: A preliminary
Assessment, final report 1986-1987". National Academy of Sciences
report #AD-A185903, 1987.
[C11] Eklund, P. M. "Quark-Catalyzed Fusion-Heated Rockets", AIAA
paper number 82-1218 presented at AIAA/SAE/ASME 18th Joint
Propulsion Conference, Cleveland, Ohio, 21-23 June 1982.
C.6d Nuclear Explosions
C.7 Matter Conversion Sources
C.7a Antimatter
[C12] Hora, H.; Loeb, H. W. "Efficient Production of Antihydrogen by
Laser for Space Propulsion", Z. Flugwiss. Weltraumforsch., v. 10 no. 6
pp 393-400, November-December 1986.
[C13] Forward, R. L., ed. "Mirror Matter Newsletter", self published, all
volumes, contains extensive bibliography.
C.7b Quantum Black Hole
-----------------------------------
Section D: Propulsion Concepts List
-----------------------------------
This section lists propulsion concepts grouped into categories by type.
D.1 Structural Methods
D.1a Static Structures
Static structures have parts which are mostly fixed in relation to each other,
although the structure as a whole may move with respect to the ground.
Large structures are primarily governed in their design by the ratio of
strength to density, or specific strength. Other important properties in
certain cases include stiffness, temperature dependance of properties, and
resistance to decay from the surrounding environment.
Methods of movement on the structure include: (i) Standard elevator: (refer
to standard engineering references for design details) (ii) Inchworm type
winch: A small motor driven trolley pulls a length of cable behind it as it
climbs up the structure. It then hooks the cable to a fixed point on the
structure. The cargo elevator remains attached to the next lower point on the
structure during this time. The elevator then uses an on-board winch to reel
itself up from one attachment point to the next. This type of winch is
useful where continuous attachment track or full length elevator cable would
be too heavy. Requires independant power for winch. (iii) Fluid transfer in
pipes: For example, Dr. Dana Andrews has suggested pumping gas
generated on the Lunar surface up to the Lunar L2 point. A column of
Oxygen at .1 atmosphere at L2, and a temperature of 1000 K (a solar heated
pipe can be used to keep the gas hot) would have a pressure of 2310 atm
(234 MPa) at the bottom. Another approach is to have pumping stations
spaced along the tower.
1 Large Towers
Alternate Names:
Type: C.1b/B.2a (Potential Energy via Mechanical Traction)
Description:
Use of advanced aerospace materials makes possible the construction of
towers that are many kilometers tall. Such towers can be used as a
high altitude platform, as a launch platform for a propulsive vehicle, or a
support structure for an accelerator system. Structural design is a major
issue.
If a tall structure is being considered, the weight of the tower structure
becomes the driving issue, because it can end up being many times the
weight of the 'payload' the tower is supporting. If the 'payload' is at the
top of the tower, the structure just underneath only has to support the
payload's weight. The next piece of structure below that must support the
payload plus the top bit of structure, so it has to be a little bit beefier
(have a larger cross sectional area). Going down the structure, it has to
get stronger and stronger to support the greater weight above.
To put some numbers to the problem, let us take a plain carbon steel
structure (the type of steel used for ordinary building construction). It
has an allowable load of 125 MPa. To make the problem simple, assume we
are holding up a 1275 kg payload on top of the tower, which under one
gravity has a weight of 12,500 N. Therefore we need one square centimeter
of cross sectional area of steel to hold up the weight. Steel has a density
of 7800 kg per cubic meter. The top meter of the tower has a volume of
0.01x0.01x1.0= 0.0001 cubic meter. This has a mass of 0.78kg. So the
structure 1 meter down from the top has to support a mass of 1275.78 kg,
i.e. the payload plus the top meter of steel. The load has increased by
0.06%, so the cross sectional area also increases by 0.06%. The area
increases in a compound interest fashion at the rate of 0.06% per meter as
you go down the tower. Over the course of 1 km in height, the increase is
by a factor of 1.8433.
We define the scale height of a structure as the length over which the cross
sectional area increases by a factor of e (2.71828...). In the case we have
been using it is 1635 meters. The scale height can be found by dividing the
allowable load of the material by the density times the local acceleration
(one gravity in the case of the Earth):
h(scale) = load / (density x acceleration)
= 125 MPa / (7800 kg/m^3 x 9.80665 m/s^2) = 1635 meters
So a tower 4.9 km tall would have an area at the bottom e cubed (20.08)
times the area at the top, and the weight of steel would be e^3 - 1, or
19.08 times the payload weight.
Now, plain carbon steel is not a very good material to use if you want a
really big tower. Let us look at advanced carbon composites, such as is
used in modern aircraft and spacecraft. One specific formulation (Amoco
T300/ERL1906 if you must know) has a compressive strength of 1930 MPa
(280,000 psi). We derate this by half to get the allowable load. This is
the same as is done for the steel, where you only use 50% of the strength to
give you a safety margin. So we have 965 MPa (140,000 psi) as an
allowable load. The density is 1827 kg/m3 (0.066 lb/cu in.) Dividing we
have a scale height of 53,878 meters (176,800 feet, or 33.5 miles) If you
build several scale heights tall, you can see in theory you could build
structures hundreds of kilometers tall.
In a real structure the payload probably won't all be at the top. For the
bottom 20 kilometers or so wind loads, ice build-up, and other
environmental effects have to be accounted for. Above this height, atomic
oxygen can attack your carbon/epoxy structural material, so a protective
layer is needed. This adds weight so there will be some reduction in how
high you can build. But you still can build many times taller than anything
built so far.
These types of towers can be built 'from the top down' in order to avoid
construction work in a vacuum. In this process, the top section of the tower
is assembled at ground level. Jacks raise the section up by one section
length. The next section down is then installed underneath. The process is
repeated for the whole tower height, so all the construction work takes place
near ground level. Special anchoring provisions are required to stabilize
the tower while being built in this fashion.
Status:
The tallest existing structure is a TV antenna which is 655m (2150 ft ) tall.
Some engineering/ architectural studies on very large towers have been
done. No attempts to build anything over 1000 meters tall are known. This
concept should be within current technology for structural materials,
although it may require an advance in construction techniques.
1a Unguyed Mast
In this approach the base of the tower needs to be 1/10 to 1/20 of the tower
height to provide stability. In the lower part of the tower, wind loads will
require the base to spread at a greater slope than the upper part, which only
depends on buckling for its necessary base width. This approach assumes
that most of the loads on the tower act vertically, as in an elevator riding
up and down the tower height.
1b Guyed Mast
If the loads are substantially sideways the tower mast may be stabilized by a
set of guy wires that spread out at a 30-45 degree angle.
1c Series of Towers
A very long, tall structure, such as a 300 km long electromagnetic
accelerator, may use a series of towers as supports.
References:
2 Tethers
Alternate Names: Beanstalks, Jacob's Ladder, Space Bridge,
Geosynchronous Towers
Type:
Description:
Tensile members in orbit store and transfer momentum to vehicles. The
tethers may be gravity-gradient stabilized or rotating endwise. A ground-to-
geosynchronous cable is not feasible with today's structural materials.
Tethers, of which a geosynchronous cable is a special case, obey an
exponential mass-ratio-to-payload-weight relation similar to that for
chemical rockets. It is possible, with existing materials, to build tethers
which will provide several km/s of delta v. In a launch system application,
an orbiting tether can be set rotating so that the lower end travels slower
than orbital velocity. A launch vehicle could rendezvous with the tether,
drop a payload, then release. Since only the payload remains in orbit, the
propulsion system on the tether only has to provide momentum to add to the
payload; the launch vehicle never has to take itself to orbital velocity.
In this case the tether acts as a 'momentum bank', lending velocity to the
launch vehicle temporarily while the payload is unloaded.
Tethers are the generalization of the 'beanstalk' or geosynchronous tower
concept. In the original concept, a cable is placed so that it hangs vertically
over the equator, and is in a 24 hour orbit. It thus appears to hang
vertically over one spot on the Earth. The task of reaching Earth orbit then
reduces to a very long (35,000 km) elevator ride. Unfortunately for the
original idea, tensile strengths approaching 2 million pounds per square inch
(12.5 GPa) are required for reasonable designs.
Tethers generalize on the original concept by (1) allowing any length, (2)
allowing any orbital period, (3) allowing any swinging or rotating states,
and, (4) allowing multiple tethers to be connected in various geometries.
One simple case would be a tether vertically oriented in earth orbit, spanning
the altitudes from 300km to 2000km. A cargo could be carried on an
elevator over this altitude range. While it is not as elegant as the
geosynchronous case, it is constructable with existing materials.
Material strength to density ratio is the critical criterion for designing
tethers. To build a minimum mass tether, one wishes to taper it's cross
section by a factor of e per scale length. The scale length is the length
at which under one gravity, the weight of a constant section cable equals
the tensile strength (i.e. just breaks). While the gravitational field
around a planet is non-uniform, the 'depth' of the gravity well is equal
to the surface gravity times the radius of the planet. The following
table shows the taper factors derived for each gravity well given materials
available at different times:
========================================================================
Taper Factors Required For Various Gravity Wells and Technology Levels |
------------------------------------------------------------------------
Gravity Depth ---------------- Time Period --------------
Well (g-km) 1960s 1970s 1980s 1990s 2000s
---------- ------ ----- ----- ----- ----- -----
Moon's 287 21 3.1 2.5 2.1 1.9
Mars' 1289 7.8E5 160 58 28 17
1/2 Earth's 3190 3.8E14 2.7E5 2.3E4 4000 1060
Earth's 6375 1.4E29 7.2E10 5.1E8 1.5E7 1.1E6
------------------------------------------------------------------------
Material Fiber- Kevlar Carbon Carbon Adv.
glass Carbon
Tensile Str. (MPa) 2410 3625 5650 6895 8273
Density (kg/m^3) 2580 1450 1810 1827 1840
Scale length (km@1g) 95 255 318 385 458
========================================================================
Status:
Variations:
2a Orbital Hanging Tether
2b Orbital Rotating Tether
2c Terrestrial Tether
One vehicle pulls another without direct mechanical attachment. Allows
modification of one vehicle without reconfiguration of joined pair. Allows
one type of vehicle to pull another. Reduces loads on lead vehicle by
lift-to- drag ratio.
References:
[D1] Ebisch, K. E. "Skyhook: Another Space Construction Project",
American Journal of Physics, v 50 no 5 pp 467-69, 1982.
[D2] Carroll, J. A. "Tether Space Propulsion", AIAA paper 86-1389, 1986.
[D3] Penzo, P.A. and Mayer., H.L. "Tethers and Asteroids for Artificial
Gravity Assist in the Solar System" Journal of Spacecraft and Rockets, Jan-
Feb 1986. (Details how a spacecraft with a kevlar tether of the same mass
can change its velocity by up to slightly less than 1 km/sec. if it is
travelling under that velocity wrt a suitable asteroid.)
[D4] Baracat, William A., Applications of Tethers in Space: Workshop
Proceedings Vols 1 and 2. (Proceedings of a workshop held in Venice,
Italy, Octover 15-17, 1985) NASA Conference Publication 2422, 1986.
[D5] Anderson, J. L. "Tether Technology - Conference Summary",
American Institute of Astronautics and Aeronautics paper 88-0533, 1988.
[D6] Penzo, Paul A. and Ammann, Paul W. Tethers in Space Handbook,
2nd Edition, NASA Office of Advanced Program Development, 1989.
(NTIS N92-19248/3)
3 Aerostat
Alternate Names: High altitude balloon
Type:
Description:
One approach to minimizing drag and gravity losses is to carry a vehicle
aloft with a high altitude balloon. Research balloons have carried ton-class
payloads in the range of 15-30 km high, which is above the bulk of the
atmosphere.
Status:
Variations:
References:
4 Low-Density Tunnel
4a Light Gas Tunnel
Alternate Names:
Type:
Description:
One or more light gas balloons are strung along the path of a vehicle or
projectile. The gas has a lower density than air. The formula for drag is
0.5*C(d)*Rho*A*v^2, where Rho is the density. Thus the lower density will
lower drag.
Status:
Variations:
References:
4b Evacuated Tunnel
Alternate Names:
Type:
Description: An evacuated tunnel is supported up through the atmosphere
(as by one or more towers). A launch system such as an electromagnetic
accelerator fires a projectile up through the tunnel. Drag losses are
minimized within the tunnel, and are low in the remaining part of the
atmosphere which must be traversed. If the top end requires some means of
keeping air from flowing in and filling the tunnel - such as a hatch that
remains closed until the accelerator is about to fire.
Status:
Variations:
References:
D.1b Dynamic Structures
Static structures rely on the strength of materials to hold themselves up.
Dynamic structures rely on the forces generated by rapidly moving parts to
hold up the structure. The advantage of this approach is it can support
structures beyond the limits of material strengths. The disadvantage is that
if the machinery that controls the moving parts fails, the structure falls
apart.
5 Fountain/Mass Driver
Alternate Names:
Type:
Description:
An electromagnetic accelerator provides a stream of masses moving up
vertically. A series of coils decelerates the masses as they go up, then
accelerates them back down again, at a few gravities. When they reach
bottom, the accelerator slows them down and throws them back up again, at
hundreds of gravities. Thus the accelerator is many times shorther than the
fountain height. The reaction of the coils to the acceleration of the fountain
of masses provides a lifting force that can support a structure. The lifting
force is distributed along where the coils are located. This can be along the
length of a tower, or concentrated at the top, with the stream of masses in
free-flight most of the way.
Status:
Variations:
References:
6 Launch Loop
Alternate Names:
Type:
Description:
A strip or sections of a strip are maintained at super-orbital velocities. They
are constrained by magnetic forces to support a structure, while being
prevented from leaving orbit. A vehicle rides the strip, using magnetic
braking against the strip's motion to accelerate. Several concepts using
super-orbital velocity structures have been proposed. One is known as the
'launch loop'. In this concept a segmented metal ribbon is accelerated to
more than orbital velocity at low Earth orbit. The ribbon is restrained from
rising to higher apogees by a series of cables suspended from magnetically
levitated hardware supported by the ribbons. The ribbon is guided to
ground level in an evacuated tube, and turned 180 degrees using magnets on
the ground. A vehicle going to orbit rides an elevator to a station where the
cable moves horizontally at altitude. The vehicle accelerates using magnetic
drag against the ribbon, then releases when it achieves orbital velocity.
J
Status:
Variations:
References:
7 Multi-Stage Tethers
Alternate Names:
Type:
Description:
A multi-stage tether has more than one tether, with the tethers in relative
motion. For example, a vertically hanging tether in Earth orbit can have a
rotating tether at it's lower end. The advantage of such an arrangement is to
lower the mass ratio of tether to payload compared to a single tether. The
mass ratio of a rotating tether is approximately proportional to exp(tip
velocity squared). If two tethers each supply half the tip velocity, then the
ratio becomes exp(2(tip velocity/2)squared), which is a smaller total mass
ratio.
Another feature of a multi-stage tether is that the tip velocity vector of the
two stages add. Since one rotates with respect to the other, the sum of the
vectors changes over time. Given suitable choices of tip velocities and
angular rates, one can receive and send payloads with arbitrary speed and
direction up to the sum of the two vectors.
Status:
Variations:
References:
--
Dani Eder/Rt 1 Box 188-2/Athens AL 35611/(205)232-7467
|
| 311.29 | Canonical List Version 0.75 - Part 2 of 4 | MTWAIN::KLAES | Houston, Tranquility Base here... | Tue Jul 05 1994 15:39 | 824 |
| Article: 2392
From: [email protected] (Dani Eder)
Newsgroups: sci.space.tech
Subject: Canonical List of Space Transport Methods (2/4)
Date: 1 Jul 94 18:17:30 GMT
Organization: Boeing AI Center, Huntsville, AL
D.2 Guns and Accelerators
D.2a Mechanical Accelerators
8 Leveraged Catapult
Alternate Names:
Type:
Description:
A leveraged catapult uses a relatively large or heavy driver to accelerate a
smaller payload at several gravities by mechanical means. Devices such a
multiple sheave pulley or a gear train convert a large force moving slowly to
a small force moving fast, and transmit the force along a cable.
The mechanical advantage produces more than one gravity of acceleration.
This concept may be the simplest to implement on a small scale. It consists
of a large weight connected via cableJ and pulley arrangement to a much
lighter projectile. The weight is allowed to fall under gravity, and the
projectile accelerates at much more than one gravity due to the mechanical
leverage of the pulley.J Despite the seeming simplicity of the concept,
velocities of severalJ km/s are possible, which would greatly reduce the size
of a rocket needed to provide the balance of the velocity.
The performance of this concept reaches a limit due to the weight, drag, and
heating of the cable attached to the payload and the magnitude of the driving
force, which is divided by the leverage ratio to yield the force on the
payload.
Status:
Variations:
8a Drop Weight
A falling mass is connected to a vehicle by a multiple-sheave pulley and
high strength cable. Two types of location are possibilities - river gorges
and mountain peaks. Locations such as the Grand Canyon and the
Columbia River gorge have lots of vertical relief for the drop weight. At
these locations the weight can consist of a large fabric bag filled with water
from the river at the bottom. The bag can be emptied before hitting bottom.
This reduces the weight that has to be stopped by a braking system.
For mountain peak locations, the drop weight runs down a set of rails and is
stopped by running into a body of water or running up an opposing hillside
plus possibly wheel braking. The mountain location may be preferred
because of the greater launch altitude.J
8b Locomotive Driver
A set of railroad locomotives provides the motive force, which is multiplied
by a gear mechanism to a higher speed. Example: launching a 20,000 lb
vehicle at 3 g's to 1100 m/s:
% Need 20 km straight run of rail.
% Rail cars needed:
- 1 tank car
- 1 car special purpose to carry glider
- 2-3 cars with tow rope guides
- 1 car pulley system
- 30 locomotives in tandem
We assume the locomotive top speed is about 27 m/s, therefore a 40:1 gear
ratio will provide the desired speed at the vehicle. Locomotive traction
averages 80,000 lb/engine, or 2000 lb per engine when reduced through the
gear ratio. The gear-down mechanism and launch cable drum are mounted
on a flatbed rail car. This car can be anchored to a foundation on either side
of the railroad track to hold it in place when the combined pull of the
locomotives is exerted. The starting traction of 30 locomotives is 1800
tons. Since the couplings between engines are probably not designed for
this load, a set of steel cables on both sides of the locomotives are used to
transmit the traction force from each engine to the gear mechanism. The
vehicle is attached to the anchored rail car by a high-strength cable which is
20 km long. At 3 g's it takes this distance to accelerate to the desired speed.
Two or three rail cars are spaced out along the 20 km with erectable towers
with a pulley wheel on top, to guide the cable and keep it off the ground
during the initial acceleration. The vehicle has glider type wings attached
that will generate lift as it gains speed, so the vehicle will climb once it
reaches 100 m/s or so. When the vehicle reaches the desired speed, the
cable is released and the vehicle continues to climb under the glider's lift.
Eventually the glider drops the vehicle, which proceeds under rocket power.
A small prototype:
Single Locomotive driver. 1250 lb rocket @ 4 g peak. Final velocity = 700
m/s. Accel time = 17.5 sec distance = 0.5at2 = 6.1 km. Engine traction =
80,000 lb average @ 25:1 gear ratio.
8c Jet Driver
This is similar to the locomotive case, but the gear ratio is lower since the
jet can reach a higher speed on a take-off run. Example: an F-15 can tow
40,000 lb rope tension if near empty. @10:1 gear ratio can accelerate 1000
lb object @ 4 g's. Aircraft top speed on deck = 300 m/s. Object top speed
in theory would be 3000 m/s. In practice would be limited by aerodynamics
and cable heating (perhaps to 1500 m/s? limit is not well understood)
References:
9 Rotary Sling
Alternate Names: Centrifuge Catapult
Type:
Description:
In principle, this is a sling or bolo scaled up and using aerospace materials.
A drive arm is driven in rotation by some means. A cable with the payload
attached to the end is played out gradually as the system comes up to speed.
The drive arm leads the cable slightly so the cable and payload see a torque
that continues to accelerate them. When the desired payload velocity is
reached, the payload releases and flies off. The cable is then retracted and
the drive arm slows down. When it stops, another payload is attached.
In a vacuum, such as on the Lunar surface, this is theoretically a very
efficient system, as the sling can be driven by an electric motor and the
mechanical losses can be held to a low value. Some method of recovering
the energy of the arm and cable (such as by transferring it to a second
system by using the motor as a generator), can lead to efficiencies over 60%
in theory.
On Earth such a system is hindered by air drag. One method of reducing
drag is to attach a shaped fairing to the cable material, so as to lower
drag compared to a circular cable. Another is to mount the drive arm on the
top of a large tower, so the cable is not moving in dense air. A third is to
generate lift along the cable or at the payload, so the rapidly moving part of
the cable, near the payload, is at a high altitude, where there is less drag.
Example #1: Single cable
% Assume v(tip) = 3000 m/s and a(tip) = 1000 m/s2
% Then r = 9000 meters.
% For 1000 kg projectile at end, cable tension is 1 MN. If carbon fiber at
3400 MPa design stress, then cable area is 1/3400 m2, or about 3 cm2.
% Cable weight is 0.6 kg/meter, adds 600 N/meter at tip, or 0.06%/meter.
Over 9 km, area
increases by factor of 6.
% Accelerating force to spin up in 1 hour is 1 m/s/s or 1000 N.
% Drag force/meter @ sea level = ~0.5 x drag force/meter at tip
= 0.5Cd rho A v2. Cd = 0.04 for shaped airfoil. rho =1.225 kg/m3 . A =
0.01 m2.
v= 3000 m/s. Drag = 2205 N/m x 0.5 factor = 1102 N/m.
% Want drag<= spin up force, thus want drag < 0.11 N/m.
% Therefore want air density at 10-4 x sea level = 240,000 ft = 73 km high.
% Thus put 9000 meter cable at top of 73 km tall tower with drive motor to
spin up cable.
Example #2: Two Stage Centrifuge Catapult
% High g's small payload catapult.
% Assume 3 km/s/stage
% 33 g's in 1st stage and 67 g's in second stage.
(this example is incomplete)
Status:
Variations:
References:
D.2b Artillery
10 Solid Propellant Charge
Alternate Names:
Type:
Description:Explosive vaporizes behind projectile in barrel. Gas pressure
accelerates projectile to high velocity. Conventional artillery reaches speeds
of around 1000 m/s.
Status: Artillery has a long history and extensive use. The High Altitude
Research Probe project attached two naval gun barrels in series and used
relatively light shells to reach higher muzzle velocities than conventional
artillery.
Variations:
References:
11 Liquid Propellant Charge
Alternate Names:
Type:
Description: Similar to conventional solid propellant artillery except liquid
propellants are metered into the chamber, then ignited. Liquid propellants
have been studied because they produce lighter molecular weight
combustion products, which leads to higher muzzle velocities, and because
bulk liquids can be stored more compactly than shells, and require less
handling equipment to load.
Status:
Variations:
References:
12 Gaseous Charge
12a Fuel-Oxidizer Charge
Alternate Names:
Type:
Description: Similar to conventional artillery except gaseous propellants are
metered into the chamber. This is essentially what happens in the cylinder
of a car engine, as a point of reference.
Status: Used as the driver for the Livermore gas gun (fuel-air mix drives 1
ton piston, which in turn compresses hydrogen working gas).
Variations:
References:
12b Scramjet Gun
Alternate Names: Ram Accelerators
Type:
Description:
Fuel/oxidizer mixture present in barrel is burned as projectile travels up
barrel. If projectile shape resembles two cones base to base, as in an inside-
out scramjet, the gas is compressed between the projectile body and barrel
wall. The combustion occurs behind the point of peak compression, and
produces more pressure on the aft body than the compression on the fore-
body. This pressure difference provides a net force accelerating the
projectile.
One attraction of this concept is that a high acceleration launch can occur
without the need for the projectile to use onboard propellants. If the
projectile has a inlet/nozzle shape (hollow in the middle) it might continue
accelerating in the atmosphere by injecting fuel into the air-only incoming
flow, extending the performance beyond what a gun alone can do. Another
attraction of this concept is the simplicity of the launcher, which is a
simple tube capable of withstanding the internal pressure generated during
combustion.
Status: Research being performed at the University of Washington under
Prof. Adam Bruckner. Research gun in basement of building.
Variations:
References:
[ D7] A. Hertzberg, A.P. Bruckner, and D.W. Bogdanoff, "The Ram
Accelerator: A New Chemical Method of Accelerating Projectiles to
Ultrahigh Velocities" , AIAA Journal, Vol. 26, No. 2, February, 1988.
(The seminal reference.)
[ D8] P. Kaloupis and A.P. Bruckner, "The Ram Accelerator: A
Chemically Driven Mass Launcher" , AIAA Paper 88-2968,
AIAA/ASME/SAE/ASEE 24th Joint Propulsion Conference, July 11-13,
1988, Boston, MA. (Applications to surface-to-orbit launching.)
[ D9] Breck W. Henderson, "Ram Accelerator Demonstrates Potential for
Hypervelocity Research, Light Launch," , Aviation Week & Space
Technology, September 30, 1991, pp. 50-51.
[ D10] J.W. Humphreys and T.H. Sobota, "Beyond Rockets: the
Scramaccelerator" , Aerospace America , Vol. 29, June, 1991, pp. 18-21.
13 Rocket Fed Gun
Alternate Names:
Type:
Description: Rocket engine at chamber end of gun produces hot gas to
accelerate projectile. In a conventional gun, all the gas is formed at once as
the charge goes off. In this concept the gas is produced by a rocket type
engine and fills the barrel with gas as the projectile runs down it. Compared
to a conventional gun, the peak pressure is lower, so the barrel is lighter.
Status:
Variations:
References:
D.2c Light Gas Gun
Light gas guns are designed to reach higher muzzle velocities than
combustion guns. They do this by using hot hydrogen (or sometimes
helium) as the working gas. These have a lower molecular weight, and
therefore a higher speed of sound. Guns are strongly limited by the speed
of sound of the gas they use. The drawback to light gas guns is that the gas
does not generate high pressures and temperatures by itself (as do
combustion byproducts). Therefore some external means are required to
produce the gas conditions desired.
14 Pressure Tank Storage
Alternate Names:
Type:
Description: The gas is stored in a chamber, then adiabatically expanded
in a barrel, doing work against a projectile.
Status:
Variations:
References:
[D11] Taylor, R. A. "A Space Debris Simulation Facility for Spacecraft
Materials Evaluation", SAMPE Quarterly , v 18 no 2 pp 28-34, 1987.
15 Underwater Storage
Alternate Names:
Type:
Description:
In a gas gun on land the amount of structural meterial in the gun is governed
by the tensile strength of the barrel and chamber. In an underwater gun, an
evacuated barrel is under compression by water pressure. The gas pressure
in the gun can now be the external water pressure plus the pressure the
barrel wall can withstand in tension, which is up to twice as high as the land
version.
Other features of an underwater gun are the ability to store gas with very
little pressure containment (the storage tank can be in equilibrium with the
surrounding water), and the ability to point the gun in different directions
and elevations.
The underwater gas gun consists of a gas storage chamber at some depth in
a fluid, in this case the ocean, a long barrel connected to a chamber at one
end and held at the surface by a floating platform at the other end, plus some
supporting equipment.
The chamber is a made of structural material such as steel. An inlet pipe
allows filling of the chamber with a compressed gas. A valve is mounted
on the inlet pipe. An outlet pipe of larger diameter than the inlet pipe
connects to the gun barrel. An outlet valve is mounted on the outlet pipe.
This valve may be divided into two parts: a fast opening and closing part,
and a tight sealing part. The interior of the chamber is lined with
insulation. The inner surface of the insulation is covered by a refractory
liner, such as tungsten. An electrical lead is connected to a heating element
inside the chamber.J
An inert gas such as argon perfuses the insulation. The inert gas protects
the chamber structure from exposure to hot hydrogen, and has a lower
thermal conductivity. An inert gas fill/drain line is connected to the volume
between the chamber wall and the liner. A pressure actuated relief valve
connects the chamber with a volume of cold gas. This cold gas is
surrounded by a flexible membrane such as rubber coated fiberglass cloth.
In operation, the gas inside the chamber, the inert gas, and the
water outside the chamber are all at substantially the same pressure. Thus
the outer structural wall does not have to withstand large
pressure differences from inside to outside. One part of the chamber wall
is movable, as in a sliding piston, to allow variation in the
chamber volume. The gas in the chamber is preferably hot, so as to
provide the highest muzzle velocity for the gun. When the gun is operated,
this gas is released into the gun barrel. In order to preserve the small
pressure difference across the wall of the chamber, either the chamber
volume must decrease or gas from an adjacent cold gas bladder must replace
the hot gas as it is expelled. This arrangement prevents ocean water from
contacting the chamber walls or hot gas. In the case of the sliding
piston, the membrane collapses, with the gas formerly within it moving in
behind the piston. In the alternate case, the membrane also collapses, with
the gas formerly within it moving through a valve into the chamber.
The chamber has an exit valve which leads to the gun barrel. It also has gas
supply lines feeding the interior of the chamber and the volume between the
chamber walls. These lines are connected to regulators which maintain
nearly equal gas pressures, which in turn are nearly equal to the ocean
pressure. This allows the chamber to be moved to the surface for
maintenance, and to be placed at different depths for providing different
firing pressures or different gun elevations.
The muzzle of the gun is at the ocean surface, so elevation of the gun can be
achieved by changing the depth of the chamber end. Since the gun as a
whole is floating in the ocean, it can be pointed in any direction. Some
means for heating the gas stored in the chamber is needed, such as an
electric resistance heater. At the muzzle end of the gun, a tube surrounds
the barrel, with a substantial volume in beween the two. There are
passages through the wall of the barrel that allow the gas to diffuse into the
tube rather than out the end of the gun, thus conserving the gas.
At the muzzle of the gun is a valve which can rapidly open, and an ejector
pump which prevents air from entering the barrel. In operation, the ejector
pump starts before the gun is fired, with the valve shut. The valve is
opened, then the gun is fired. In this way, the projectile encounters only
near vacuum within the barrel, followed by air.
Status:
Variations:
References:
16 Thermal Bed Heated
Alternate Names:
Type:
Description:
Hot gas is generated by flowing hydrogen through a chamber which
contains refractory oxide particles. The particles are heated slowly (roughly
1 hour time period) by some type of heater near the center of the chamber.
This sets up a temperature gradient, so the exterior of the chamber is
relatively cool, and can thus be made of ordinary steels. When the
hydrogen flows through the chamber, the large surface area of the particles
allows very high heat transfer rates - so the heat in the chamber can be
extracted in a fraction of a second.
Example:
% To match Livermore hypersonic gun, want 40 MJ projectile energy.
% Assume losses and initial gas pressure are equal contributors.
% Want aluminum oxide to drop 500K in operation. At 1 J/K/gm, need 80
kg of
aluminum oxide. In the form of grinding wheels, we are looking at about
$600 of
materials. 25 wheels, 30 cm diam x 2.5 cm thick.
% If pressure is 3000 psi (20.7 MPa), then 10 cm diam, 5 kg projectile will
see
162,600 N force, or 32,470 m/s2. To reach 4 km/s requires 0.123 sec,
distance = 250 m.
Allow 500 m for losses. Alignment = 1/6 mm along length.
% Final gas temp average 2000 K. Barrel volume = 4 m3. Storage tank =
0.65 m3.
% Storage tank diam = 50 cm. Length = 3.3 m.
% Chamber = 32 cm diam ID x 65 cm long.
Status: A small research gun of this type has been built at
Brookhaven Natl. Lab.
Variations:
References:
17 Particle Bed Reactor Heated
Alternate Names:
Type:
Description:
Hot gas is generated by flowing through particle bed type reactor. Gas
expands against projectile, accelerating it. Light gas guns have been
operated to above orbital velocity, and 1 kg projectiles have been
accelerated to over half orbital velocity. This type of gun rapidly becomes
less efficient above the speed of sound of the gas. As a consequence the
working fluid is usually hot hydrogen. Conventional gas guns have used
powder charge driven pistons to compress and heat the gas. This is not
expected to be practical on the scale needed to launch useful payloads to
orbit. One way to heat the gas is to pass it through a small particle bed
nuclear reactor. This type of reactor produces a great deal of heat in a small
volume, since the small particles of nuclear fuel have a large surface/volume
ratio and can efficiently transfer the heat to working fluid. This uses the
benefits of nuclear power for space launch, without the drawbacks of a
flying reactor.
Status:
Variations:
References:
18 Electric Discharge Heated
Alternate Names:
Type:
Description:
Gas is heated by electric discharge, then pushes against projectile in barrel.
The limiting factor for a light gas gun is the speed of sound in the gas. One
way to heat the gas to much higher temperatures is an electric discharge
within the gas.
Status:
Variations:
References:
19 Nuclear Charge Heated
Alternate Names:
Type:
Description: Similar to artillery, except explosive in chamber is atomic
bomb. This concept makes sense in a situation where very large payloads
need to be launched. A large underground chamber is excavated, and filled
with hydrogen gas as the working fluid. A large barrel leads off the
chamber upward at an angle. A crossbar is set into the barrel near the
chamber, and the projectile is attached to the crossbar with a bolt that is
designed to fail at a pre-determined stress. This restrains the projectile
until the operating pressure is reached. A small atomic bomb is suspended
in the chamber and detonated to create lots of hot hydrogen in a very short
time.
Status:
Variations:
References:
20 Combustion Driven Piston
Alternate Names:
Type:
Description: This is a type of two-stage gas gun. A cylindrical chamber
contains a piston. On the back side of the piston high pressure gas is
generated by combustion. This can be gunpowder or a fuel-air mixture. On
the front side of the piston is the working gas, which is usually hydrogen.
The hydrogen is compressed and heated until a valve or seal is opened.
Then the working gas accelerates the projectile.
Status: This type of gas gun is the most common that has been built.
They were first constructed in the 1960's or earlier. The largest gun of this
type is a Lawrence Livermore Laboratory, where it is being used to test
scramjet components at 2.4 km/s (Mach 8) (Dec. 1993). It has a 4
inchx150ft barrel and a larger diameter, 300 ft long chamber.
Variations:
References:
[D12 ] Aviation Week & Space Technology, July 23, 1990.
[D13 ] "World's Largest Light Gas Gun Nears Completion at Livermore."
Aviation Week & Space Technology, August 10,1992.
21 Gravity Driven Piston
Alternate Names:
Type:
Description:
A sliding or falling mass is used to compress gas in a chamber. The gas is
then expanded in a barrel. An alternate method of compressing and heating
the working fluid in a light gas gun is a rapidly moving, massive piston. If
the gun is built on the side of a mountain, the energy for launch is stored as
potential energy in the piston. The piston floats on an air or lubricated
bearing and slides down the mountain to a cylinder. The cylinder leads to a
barrel containing the projectile, which accelerates upward.
Status:
Variations:
References:
D.2d Electric Accelerators
Electric accelerators typically require high peak power for a short period of
time. Hence inexpensive energy storage is very important for these
concepts. Two places to look for inexpensive energy storage are (1)
Magnetic fusion experiments, and (2) Inductive energy stores. The latter
falls into subcategories: cooled normal conductors, and superconductors.
22 Railgun
Alternate Names: Electromagentic Gun
Type:
Description:
High current electricity supplied by rails is shorted through plasma arc.
Plasma is accelerated by reaction against magnetic field produced by
current. Plasma pushes projectile. A railgun uses magnetic forces to
accelerate payloads. Typically two parallel conducting rails are bridged by a
plasma arc. The plasma is accelerated downJthe gun by the arrangement of
currents and fields. Given suitable power supplies, it can be considered for
earth launch systems at lower accelerations than those proposed for weapon
systems.
Status:
This device was under intensive development for the Strategic Defense
Initiative. A large gun was built at Eglin AFB in Florida and used a bank of
thousands of car batteries wired in parallel as a power supply. Prototype
railguns achieved high velocities, but the high currents produced rail
erosion.
Variations:
References:
[D14] Robinson, C. A. "Defense Department Developing Orbital Guns",
Aviation Week and Space Technology, v 121 no 12 pp 69-70, 1984.
[D15] Bauer, D. P. et al "Application of Electromagnetic Accelerators to
Space Propulsion" IEEE Trans. Magnetics vol MAG-18 no 1 pp 170-5,
Jan. 1982.
23 Coilgun
Alternate Names: Mass Driver Launcher
Type:
Description:
Series of coils forming gun react with coil(s) on projectile magnetically,
producing thrust. Popularly known as a 'mass driver', this concept uses
magnetic attraction between two current carrying coils to accelerate a
projectile. The concept has been developed in connection with launching
lunar materials for space manufacturing.J Accelerator designs with high
efficiency (>90%) and high muzzle velocitiesJ (>8 km/s) have been
proposed. This potentially leads to a transportationJ system whose
operating costs consist mostly of electricity, or $0.28/lb. Laboratory
versions of electromagnetic accelerators have reached 1800 gravities
acceleration. Accelerations in the range of ~100 gravities are sufficient for
cargo launch from the surface of the earth.
Status:
Variations:
References:
[D16] Nagatomo, Makoto; Kyotani, Yoshihiro "Feasibility Study on
Linear-Motor-Assisted Take-Off (LMATO) Of Winged Launch Vehicle",
Acta Astronautica, v 15 no 11 pp 851-857, 1987.
[D17] Kolm, H.; Mongeau, P. "Alternative Launching Medium", IEEE
Spectrum, v 19 no 4 pp 30-36, 1982.
[D18] Kolm, H. "An Electromagnetic 'Slingshot' for Space Propulsion",
Spaceworld pp 9-14, Feb. 1978.
D.3 Combustion Engines
D.3a Air-Breathing Engines
Concepts 24 through 27 all involve using a planet's (usually the Earth's)
atmosphere as a supply of oxygen to support combustion with a fuel carried
on the vehicle. It should be noted that some vehicle concepts (such as the
National Aerospaceplane (NASP) would integrate more than one engine
concept in a single engine. For example, most NASP configurations would
have ramjet and scramjet propulsion combined in the same engine.
24 Fanjet
Alternate Names:
Type:
Description:
The fanjet is the standard type of jet engine found on passenger aircraft and
military aircraft. The original form of the engine, the turbojet, has a series
of turbine compressor stages to compress the incoming air flow. This is
followed by a combustor where fuel is added and burned, creating a hot
gas. The gas is then expanded through a turbine which is connected by a
shaft to the compressor. The expanded gas emerges at high velocity from
the back of the engine.
The modern fanjet adds a fan which is also driven by the turbine. All of the
airflow goes through the fan, but only a part goes into the compressor. The
air which does not go into the compressor is said to have 'bypassed' the
compressor. The 'bypass ratio' is the ratio of bypass air to combustor air.
Generally higher bypass ratio engines are more fuel efficient (in units of
thrust divided by fuel consumption rate). Also in general, engines that
operate at higher speeds are designed with lower bypass ratios.
Typical modern performance values are engine thrust-to weight ratios (T/W)
of 6:1 for large subsonic engines, trending towards about 10:1 for high
performance military jets. Fuel efficiency is measured in units of thrust
divided by mass flow rate. In English units this is pounds divided by
pounds per second, or just seconds, and is termed 'specific impulse'. In SI
units this is Newtons per kilogram per second, which has the units of
meters per second. In some propulsion systems, such as chemical rockets,
the SI unit corresponds to the actual exhaust jet velocity. In the case of air-
breathing propulsion it is not, the velocity result is just an indicator of
engine efficiency. In English units the performance of subsonic engines is
about 10,000 seconds, trending to about 7000 seconds for supersonic
military engines. Fanjets and turbojets operate up to about 3.5 times the
speed of sound (M=3.5).
Status:
In common use on aircraft for aircraft propulsion. The B-52 bomber has
been used to carry the Pegasus three stage solid rocket to 35,000 ft
altitude. The B-52 uses 8 fanjet type engines for propulsion. Numerous
paper studies have been made of using aircraft as carriers for rocket stages.
Variations:
References:
25 Turbo-Ramjet
Alternate Names:
Type:
Description:
A fan compresses incoming air stream, which is then mixed with fuel,
burned and exhausted. Compressor is driven by gas generator/turbine. In a
fanjet, the incoming air is compressed and heated by the compressor stages,
then mixed with fuel and run through the turbine stages. At higher
velocities the air gets hotter in compression since it has a higher incoming
kinetic energy. This leads to a higher turbine temperature. Eventually a
turbine temperature limit is reached based on the material used, which sets a
limit to the speed of the engine. In the turbo-ramjet the compressor is
driven by a gas generator/turbine set which use on-board propellant for their
operation. Since the gas generator is independant of the flight speed, it can
operate over a wider range of Mach numbers than the fanjet ( to Mach 6 vs.
to Mach 3)
Status:
Variations:
References:
26 Ramjet
Alternate Names:
Type:
Description:
Incoming air stream is accelerated to subsonic relative to engine, mixed
with fuel, then exhausted. The incoming air is moving at the vehicle
velocity entering the engine. After burning the fuel, the air is hotter and
can expand to a higher velocity out the nozzle. This sets up a pressure
difference that leaves a net thrust. Ramjets cannot operate at zero speed, but
they can reach somewhat higher limits than an engine with rotating
machinery (range Mach 0.5 to about Mach 8).
Status:
Variations:
References:
27 Scramjet
Alternate Names:
Type:
Description:
Incoming air stream is compressed by shock waves, mixed with fuel, and
expanded against engine or vehicle. Tha airstream remains supersonic
relative to the vehicle. The forward thrust is produced by expanding the
exhaust against a nozzle shape. Even though the gas is moving
supersonically relative to the vehicle, the sidewise expansion can act on the
vehicle if the slope of the nozzle is low enough. Thus the vehicle can fly
faster than the exahust gas moves. Scramjets may provide useful thrust up
to about Mach 15, or 60% of orbital speed.
Status:
Variations:
References:
28 Inverted Scramjet
Alternate Names: Buoyant Scramjet
Type:
Description: Series of balloons floated in atmosphere through which
projectile flies. Projectile carries oxygen and flies through hydrogen
(oxygen is much denser, so cross section is reduced.
Status:
Variations:
References:
29 Laser-Thermal Jet
Alternate Names:
Type:
Description: Laser is focussed and absorbed in heat exchanger, or laser-
sustainedJ plasma.J
Status:
Variations:
References:
[D19] Myrabo, L. N. "Concept for Light-Powered Flight", AIAA paper
number 82-1214 presented at AIAA/SAE/ASME 18th Joint Propulsion
Conference, Cleveland, Ohio, 21-23 June 1982.
D.3b Internally Fuelled Engines
30 Solid Rocket
Alternate Names:
Type:
Description: A solid rocket consists of a high-strength casing, a nozzle,
and a solid propellant grain which burns at a pre-designed rate. The grain
is a mixture of materials containing both fuel and oxidizer, so combustion
can proceed without any external action once it is ignited. Modern solid
propellants have a formulation close to the following: About 15% by
weight organic fuel, usually a type of rubber, about 20% by weight
aluminum powder (which acts as a metallic fuel), and about 65%
ammonium perchlorate
(NH3ClO4), which is the oxidizer. About 1-2% epoxy is added to the
powders to hold them together. The epoxy, being an organic material, is
also part of the fuel.
Status:
Variations:
References:
31 Hybrid Rocket
Alternate Names:
Type:
Description: The hybrid rocket consists of a solid fuel grain and a liquid
oxidizer. One combination is rubber for the fuel and liquid oxygen for the
oxidizer. The fuel is in the form of a hollow cylinder or perforated block.
The oxidizer is sprayed onto the fuel and the material is ignited. By not
being self-supporting in combustion, the fuel part can be treated as non-
hazardous when being made and shipped. Only when on the launch pad and
the oxidizer tank is filled is there a hazardous combination. With only a
single liquid to handle, the harware is relatively simple in design.
Status:
Variations:
References:
32 Liquid Rocket
Alternate Names:
Type:
Description: Mixture of fuel and oxidizer are burned in combustion
chamber which leads to a converging-diverging nozzle. The flow becomes
sonic at the narrow part of the nozzle, then continues to accelerate in the
diverging part of the nozzle. This is the most common form of launch
propulsion used to date to put things in Earth orbit. A variety of propellant
combinations have been used, including mono- bi-, and even tri-propellant
combinations.
Status:
Variations: Number propellant variants by oxidizer/fuel letters (very
incomplete list of propellants)
Oxidizer Variants
Formula Mol. Wt.
a Oxygen O2 32
b Hydrogen Peroxide O2H2 34
c Fluorine F2 36
d Nitrogen Tetroxide N4O4 92
Fuel Variants
a Hydrogen H2 2
b Methane CH4 16
Pump-fed Variant
Pressure-fed Variant
References:
[D20] Cooper, Larry P. "Status of Advanced Orbital Transfer Propulsion",
Space Technology (Oxford), v 7 no 3 pp 205-16, 1987.
[D21] Godai, Tomifumi "H-II Rocket: New Japanese Launch VehicleJ in
the 1990s", Endeavour , v 11 no 3 pp 116-21, 1987.
[D22] Wilhite, A. W. "Advanced Rocket Propulsion Technology
Assessment for Future Space Transportation", Journal of Spacecraft and
Rockets, v 19 no 4 pp 314-19, 1982.
33 Gaseous Thruster
Alternate Names:
Type:
Description: The propellant is introduced in gas form to the chamber. It
may be a mono-propellant (a single gas) or a bi-propellant combination.
Status:
Variations:
References:
34 Mechanically Augmented Thruster
Alternate Names:
Type:
Description: Velocity of exaust gases is increased by placing thrusters on
end of rotating arm. Adds 200-300 sec to specific impulse based on
structual material capabilities.
Status:
Variations:
References:
--
Dani Eder/Rt 1 Box 188-2/Athens AL 35611/(205)232-7467
|
| 311.30 | Canonical List Version 0.75 - Part 3 of 4 | MTWAIN::KLAES | Houston, Tranquility Base here... | Tue Jul 05 1994 15:39 | 724 |
| Article: 2394
From: [email protected] (Dani Eder)
Newsgroups: sci.space.tech
Subject: Canonical List of Space Transport Methods (3/4)
Date: 1 Jul 94 18:18:06 GMT
Organization: Boeing AI Center, Huntsville, AL
D.4 Thermal Engines
35 Electric-Rail Rocket
Alternate Names:
Type:
Description: High voltage electricity supplied by rails is shorted through
tungsten heat exchanger, which heats hydrogen carried by vehicle flying
between rails.
Status:
Variations:
References:
[D23] Wilbur, P. J.; Mitchell, C. E.; Shaw, B. D. "Electrothermal
Ramjet", AIAA paper number 82-1216 presented at AIAA/SAE/ASME 18th
Joint Propulsion Conference, Cleveland, OH, 21-23 June 1982.
36 Resistojet
Alternate Names:
Type:
Description: Sunlight generates electricity, which is used to heat gas
passed over or through a heating element.
Status:
Variations:
References:
[D24] Louviere, Allen J. et al "Water-Propellant Resistojets for Man-
Tended Platforms", NASA Technical Memorandum 100110, 1987.
37 Solar-Thermal
Alternate Names:
Type:
Description: Sunlight is concentrated by a reflector or lens, then heats an
absorber. The absorber transfers heat to a working fluid, usually hydrogen.
The hydrogen is then expanded through a nozzle.
Status:
Variations:
References:
[D25] Gartrell, C. F. "Future Solar Orbital Transfer Vehicle Concept",
IEEE Transactions on Aerospace Electronic Systems, vol AES-19 no 5 pp
704-10, 1983.
38 Laser-Thermal
Alternate Names:
Type:
Description:
Beam is passed through window in rocket engine. It is then absorbed by a
heat exchanger or is focussed to create laser-sustained plasma. Hot gas is
then expelled through nozzle. By using an energy source external to the
propellant, specific impulse increases of 100% can be achieved by using
hydrogen rather than oxygen/hydrogen.J One method of doing this is with a
large, ground-based laser to heat the hydrogen. This concept is applicable
from the ground to orbital velocity, and may be used in conjunction with
another concept. Use of laser propulsion only in an upper stage would
allow smaller lasersJthan are required for a first stage laser rocket, hence a
laser upper stage has nearer term technical viability than a first stage.
Status:
Variations:
References:
[D26] Abe, T.; Shimada, T. "Laser Assisted Propulsion System
Experiment on Space Flyer Unit", 38th International Astronautical
Federation Conference paper number IAF-87-298, 1987.J
[D27] Abe, T.; Kuriki, K. "Laser Propulsion Test Onboard Space
Station", Space Solar Power Review vol 5 no 2 pp 121-5, 1985.
[D28] Jones, L. W.; Keefer, D. R. "NASA's Laser Propulsion Project",
Astronautics and Aeronautics, v 20 no 9 pp 66-73, 1982.
39 Laser Detonation-Wave Engine
Alternate Names:
Type:
Description:
Propellant is a solid block with a flat bottom. First laser pulse evaporates a
layer of propellant. Second, larger, pulse creates plasma detonation wave,
which shocks and heats the propellant layer. Layer expands against base of
solid block.
Status:
Variations:
References:
[D29] Kare, J.T. "SDIO/DARPA Workshop on Laser Propulsion, Volume
1: Executive Summary" Lawrence Livermore National Laboratory report
number DE87-003254, 1987.
40 Microwave Thermal
Alternate Names:
Type:
Description:
Microwaves are absorbed by engine, which becomes hot. Hydrogen is
flowed through engine, gets hot, and is then exhausted. A large phased
microwave array on the ground can focus onto a rocket-sized area over a
range of hundreds of kilometers. Given a way to couple the microwave
energy to a working fluid such as hydrogen, this type of propulsion could
provide significant launch vehicle velocities. High power microwave
amplifiers exist in a variety of forms with efficiencies up to 75% and power
levels up to one megawatt. This concept uses direct heating of the engine
structure, which acts as a heat exchanger to heat the working fluid.
Example: 10 meter diameter receiver, 5 cm wavelength, 1 km phased array,
range = 200 km.
Status:
Variations:
References:
41 Solid Core Nuclear
Alternate Names:
Type:
Description:
Hydrogen is heated by flowing through nuclear reactor, then exhausted in
rocket nozzle. Although the nuclear rocket program was stopped a number
of years ago, more recent work at Brookhaven National Laboratories on
fluidized particle bed reactors warrants their consideration for launch
vehicles. The small particle size (.3 mm) allows high heat transfer rates to
the working fluid, hydrogen, and hence potentially high thrust to weight
ratios.
Status:
Variations:
References:
[D30] Thomas, Ulrich "Nuclear Ferry - Cislunar Space Transportation
Option of the Future", Space Technology (Oxford) v 7 no 3 pp 227-234,
1987.
[D31] Holman, R.R.; Pierce, B. L. "Development of NERVA reactor for
Space Nuclear Propulsion", presented at AIAA/ASME/SAE/ASEE 22nd
Joint Propulsion Conference, Huntsville, Alabama, 16-18 Jun 1986, AIAA
paper number 86-1582, 1986.
[D32] Thom, K. et al "Physics and Potentials of Fissioning Plasmas for
Space Power and Propulsion", Acta Astronautica vol 3 no 7-8 pp 505-16,
Jul. -Aug. 1976.
[D33] DiStefano, E. "Space Nuclear Propulsion - Future Applications and
Technology", 2nd Symposium on Space Nuclear Power Systems,
Albequerque, New Mexico, 14 January 1985, pp 331-342, 1987.
42 Liquid Core Nuclear
Alternate Names:
Type:
Description: In order to attain higher performance than a solid core
rocket, the reactor core is raised to a high enough temperature to become
liquid. Hydrogen is bubbled through the liquid, then exhausted out a
nozzle.
Status:
Variations:
References:
43 Gas Core Nuclear
Alternate Names:
Type:
Description: The reactor core is hot enough that the core is gasseous in
form. The hydrogen flow is seeded with an absorbent material to directly
absorb the thermal radiation from the core. The core is kept from leaking
out the nozzle by a transparent container (nucear light bulb), a flow vortex,
which uses the density difference between uranium and hydrogen, or
magnetic separation, which uses the ionization difference between the
uranium and the hydrogen.
Status:
Variations:
References:
44 Muon-Catalyzed Fusion
Alternate Names:
Type:
Description:
A beam of muons is directed at a deuterium/tritium mixture, where the
muons catalyze mutiple fusion reactions. The heated gas powers an
electric generator to power an ion or neutral particle beam thruster.
Status:
Variations:
References:
D.5 Bulk Matter Engines
45 Rotary Flinger
Alternate Names:
Type:
Description: A one or two stage rotary mechanism mechanically
accelerates a small amount of reaction mass, then releases it. In the two
stage version, top speeds of 6 km/s are possible.
Status:
Variations:
References:
46 Coilgun Engine
Alternate Names: Mass Driver Reaction Engine
Type:
Description: A carrier, or bucket, is accelerated by interaction of
magnetic fields from 'driver' coils. The carrier holds a reaction mass,
which is released. The bucket is slowed down and reused.
Status:
Variations:
References:
47 Railgun Engine
Alternate Names:
Type:
Description:The interaction of the fields in current carrying rails and a
plasma short circuit of the rails accelerates the plasma, and anything in
front of it.
Status:
Variations:
References:
D.6 Ion and Plasma Engines
48 Arc Jet
Alternate Names:
Type:
Description:
Sunlight is converted to electricity by a photovoltaic array. The electricity
is arced through a propellant stream, heating it. The propellant is then
expanded through a nozzle.
Status:
Variations:
References:
[D34] Hardy, Terry L.; Curran, Francis M. "Low Power DC Arcjet
Operation with Hydrogen/Nitrogen/Ammoinia Mixtures", NASA
Technical Memorandum 89876, 1987.
[D35] Stone, James R.; Huston, Edward S. "NASA/USAF Arcjet
Research and Technology Program", NASA Technical Memorandum
100112, 1987.
[D36] Kagaya, Y. et al "Quasi-steady MPD Arc-jet for Space
Propulsion", Symposium for Space Technology and Science, Tokyo,
Japan, 19 May 1986, pp 145-154, 1986.
[D37] Manago, Masata et al "Fast Acting Valve for MPD Arcjet", IHI
Engineering Review, v 19 no 2 pp 99-100, April 1986.J J
[D38] Pivirotto, T. J.; King, D. Q. "Thermal Arcjet Technology for
Space Propulsion", Chemical Propulsion Information Agency, Laurel,
Maryland, 1985.
49 Electrostatic Ion
Alternate Names:
Type:
Description:
Status:
Variations:
References:
[D39] Rawlin, Vincent K; Patterson, Michael J. "High Power Ion Thruster
Performance", NASA Technical Memorandum 100127, 1987.
49a Solar-Electric Ion
Sunlight is converted to electricity by a photovoltaic array. The electricity
is used to ionize and electrostatically accelerate the propellant.
[D40] Mitterauer, J. "Liquid Metal Ion Sources as Thrusters for Electric
Space Propulsion", J. Phys. Colloq. (France) vol 48, no C-6, pp 171-6,
Nov. 1987.
[D41] Mitterauer, J. "Field Emission Electric Propulsion - Emission Site
Distribution of Slit Emitters", IEEE Trans. on Plasma Sci. vol PS-15, pp
593-8, Oct. 1987.
[D42] Stuhlinger, E. et al "Solar-Electric Propulsion for a Comet Nucleus
Sample Return Mission" presented at 38th Congress of the
International Astronautical Federation, Brighton, England, 10 Ocotober
1987.
[D43] Nakamura, Y.; Kuricki, K. "Electric Propulsion Test Onboard the
Space Station", Space Solar Power Review vol 5 no 2 pp 213-9, 1985.
[D44] Voulelikas, G. D. "Electric Propulsion: A Review of Future Space
Propulsion Technology" Communications Research Centre, Ottawa,
Ontario, report number CRC-396, October 1985.
[Dnn] Bartoli, C. et al
"A Liquid Caesium Field Ion Source for Space Propulsion", J. Phys. D vol
17 no 12 pp 2473-83, 14 Dec. 1984.
[D45] Imai, R.; Kitamura, S. "Space Operation of Engineering Test
Satellite -III Ion Engine", Proceedings of JSASS/AIAA/DGLR 17th Intl.
Electric Propulsion Conf. pp 103-8, 1984.
[D46] Jones, R. M.; Poeschel, R. L. "Primary Space Propulsion for 1995-
2000 - Electrostatic Technology Applications" AIAA/SAE/ASME 20th Joint
Propulsion Conference, AIAA paper number 84-1450, 1984.
[D47] Bartoli, C. et al "Recent Developments in High Current Liquid
Metal Ion Sources for Space Propulsion", Vacuum vol 34 no 1-2 pp 43-6,
Jan. -Feb. 1984.
[D48] Brophy, J. R.; Wilbur, P. J. "Recent Developments in Ion Sources
for Space Propulsion", Proceedings of the Intl. Ion Engineering Congress
vol 1 pp 411-22, 1983.
[Dnn] Anon. "Ion Propulsion Engine Tests
Scheduled", Aviation Week and Space Technology, v 116 no 26 pp 144-5,
1982.
[D49] James, E.; Ramsey, W., Sr.; Steiner, G. "Developing a Scaleable
Inert Gas Ion Thruster", AIAA paper number 82-1275 presented at
AIAA/SAE/ASME 18th Joint Propulsion Conference, Cleveland, OH, 21-
23 June 1982.
[D50] Zafran, S. et al "Aerospace Highlights 1982: Electric
Propulsion", Astronautics and Aeronautics, v 20 no 12 pp 71-72, 1982.
[D51] Clark, K. E.; Kaufman, H. B. "Aerospace Highlights 1981: Electric
Propulsion", Astronautics and Aeronautics, v 19 no 12 pp 58-59, 1981.
[D52] Kaufman, H. R. "Performance of Large Inert-Gas Thrusters",
AIAA paper number 81-0720 presented at 15th International Electric
Propulsion Conference, Las Vegas, Nevada, 21-23 April 1981.
[D53] Byers, D. C.; Rawlin, V. K. "Critical Elements of Electron-
Bombardment Propulsion for Large Space Systems", J. Spacecraft and
RocketsJ vol 14 no 11 pp 648-54, Nov. 1977.
[D55] Mutin, J.; Tatry, B. "Electric Propulsion in the Field of Space",
Acta Electron. (France) vol 17 no 4 pp 357-70, Oct. 1974 (in French).
49b Thermoelectric Ion
Radioactive isotope decay produces heat. Heat is converted to electricity by
semiconductors. Electricity ionizes and accelerates atoms in engine.J
49c Laser-Electric Ion
Laser tuned to optimum absorption wavelength of photovoltaic cells. Cells
convert laser light to electricity, which is used to power ion engine. Ion
engine accelerates ionized propellants electrostatically.
[D56] Maeno, K. "Advanced Scheme of CO2 Laser for Space
Propulsion", Space Solar Power Review vol 5 no 2 pp 207-11, 1985.
49d Microwave-Electric Ion
A microwave receiving antenna (rectenna) on spacecraft converts
microwaves to electricity. Electricity is used to ionize and accelerate
atoms.
[D57] Nordley, G. D.; Brown, W. C. "Space Based Nuclear-Microwave
Electric Propulsion", 3rd Symposium on Space Nuclear Power Systems,
Albuquerque, New Mexico, 13 January 1986, pp 383-95, 1987.
49e Nuclear-Electric Ion
Nuclear reactor generates heat, which is converted to electricity in
thermoelectric or turbine/generator cycles. Electricity is used to ionize
propellant and accelerate it by electrostatic voltage.
[D58] Cutler, A. H. "Power Demands for Space Resource Utilization",
Space Nuclear Power Systems 1986 pp 25-42.
[D59] Buden, D.; Garrison, P. W. "Space Nuclear Power Systems and
the Design of the Nuclear Electric Propulsion OTV", presented at
AIAA/SAE/ASME 20th Joint Propulsion Conference, AIAA paper number
84-1447, 1984.
[D60] Powell, J. R.; Boots, T. E. "Integrated Nuclear Propulsion/Prime
Power Systems", AIAA paper number 82-1215 presented at
AIAA/SAE/ASME 18th Joint Propulsion Conference, Cleveland, Ohio,
21-23 June 1982.
[D61] Powell, J. R.; Botts, T. E.; Myrabo, L. N. "Annular Bed Nuclear
Power Source for Electric Thrusters", AIAA paper number 82-1278
presented at AIAA/SAE/ ASME 18th Joint Propulsion Conference,
Cleveland, Ohio, 21-23 June 1982.
[D62] Ray, P. K. "Solar Electric versus Nuclear Electric Propulsion in
Geocentric Space", Trans. Am. Nucl. Soc. vol 39 pp 358-9, Nov.-Dec.
1981.
[D63] Hsieh, T. M.; Phillips, W. M. "An Improved Thermionic Power
Conversion System for Space Propulsion", Proceedings of the 13th
Intersociety Energy Conversion Engineering Conference pp 1917-1923,
1978.
[D64] Reichel, R. H. "The Air-Scooping Nuclear-Electric Propulsion
Concept for Advanced Orbital Space Transportation Missions", J. British
Interplanetary Soc. vol 31 no 2 pp 62-6, Feb. 1978.
50 Electron Beam Heated Plasma
Alternate Names:
Type:
Description: A high voltage (hundreds of keV) electron beam is injected
axially into a propellant flow. The electron beam heats the flow to plasma
temperatures, which produces high specific impulse. Cool gas is injected
along the chamber walls to provide film cooling and protect the chamber
from the very high temperature plasma.
Status:
Variations:
References:
51 Microwave Heated Plasma
Alternate Names: Electron-Cyclotron Absorption Rocket
Type:
Description:J Partially ionized gas directly absorbs microwaves,
becomingJhot, then expands through rocket nozzle.
Status:
Variations:
References:
52 Fusion Heated Plasma
Alternate Names:
Type:
Description: Exhaust of pure fusion rocket is a thin, extremely hot
plasma. If higher thrust is needed, hydrogen can be mixed with plasma.
This increases thrust at the expense of performance.
Status:
Variations:
References:
52a Reactor leakage mixed
52b Plasma Kernal Mixed
53 Antimatter-Heated Plasma
Alternate Names:
Type:
Description: Exhaust of pure antimatter rocket is a charged particles. If
higher thrust is needed, hydrogen can be mixed with plasma. This
increases thrust at the expense of performance.
Status:
Variations:
References:
D.7 High Energy Particles
D.7a Particle Rockets
54 Pulsed Fission Nuclear
Alternate Names: Orion
Type:
Description: A series of small atomic bombs yield debris/particles
which pushes against plate/shock absorber arrangement. The shock
absorber evens out the explosion pulses to an even acceleration for the
vehicle.
Status:
Variations:
References:
55 Microfusion
Alternate Names:
Type:
Description: A conventional atomic bomb requires a certain
minimum size to operate with reasonable efficiency (a few kilotons). In the
microfusion approach, a fuel pellet consists of a fusion core material
(deuterium/tritium) surrounded by a fission shell (uranium 235). This is
similar to the arrangement of a fusion atomic bomb. Instead of chemical
explosives, which are what trigger a fusion bomb, a set of lasers or a heavy
ion beam are used to compress and set off the fission shell, which in turn
sets off the fusion core. A laser or ion compression can get higher
compressions than a chemical explosion, thus can set off smaller pellets. It
is easier to set off a fission shell than directly causing the fusion core to
ignite (as in the inertial fusion program). If explosions in the
ton range rather than kiloton range can be achieved, it will produce a more
useful vehicle than the pulsed fission concept in the previous item.
Status:
Variations:
References:
56 Alpha Particle
Alternate Names:
Type:
Description:
Radioactive element coats one side of thin sheet which is capable of
absorbing alpha particles. Particles emitted into sheet are absorbed,
particles emitted in opposite direction escape, providing net thrust.
Status:
Variations:
References:
57 Fission Fragment
Alternate Names:
Type:
Description: Thin wires containing fissionable material are at the heart of
this concept. Thin wires are used to allow the nuclear fragments from the
fission to escape. They are aimed by electrostatic or electromagnetic fields
to mostly go out the back end of the thruster. The performance is very high
because of the high speed of the fragments.
Status:
Variations:
References:
58 Fusion Particle
Alternate Names:
Type:
Description: Various thermonuclear fusion reactors have been proposed.
The results of a fusion reaction are high energy particles which can, in
priniple, be harnessed for propulsion.
Status:
Variations:
58a Magnetic Confinement
Plasma in chamber similar to fusion power reactor is
intentionally leaked to magnetic nozzle.
References:
[D65] Freeman, M. "Two Days to Mars with Fusion Propulsion", 21st
Century Science and Technology, vol 1, pp 26-31, Mar.-Apr. 1988.
[D66] Kammash, T.; Galbraith, D. L. "A Fusion-Driven Rocket
Propulsion Scheme for Space Exploration", Trans. Am. Nucl. Soc. vol 54
pp 118-9, 1987.
[D67] Mitchell, H. M.; Cooper, R. F.; Verga, R. L. "Controlled Fusion
for Space Propulsion. Report for April 1961-June 1962", US Air Force
report number AD-408118/8/XAB, April, 1963.
58b Inertial Confinement
Fuel pellet is heated and compressed by lasers, electron beam, or ion
beam. After fusing, the resulting plasma is directed by a magnetic
nozzle.
References:
[D68] Kammash, T.; Galbraith, D. L. "A Fusion Reactor for Space
Applications", Fusion Technology, v. 12 no. 1 pp 11-21, July 1987.
[D69] Orth, C. D. et al "Interplanetary Propulsion using Inertial Fusion",
report number UCRL--95275-Rev. 1: 4th Symposium on Space Nuclear
Power Systems, Albequerque, New Mexico, 12 January 1987.
[D70] Hyde, Roderick, "A Laser Fusion Rocket for Interplanetary
Propulsion" , LLNL report UCRL-88857. (Fusion Pellet design: Fuel
selection. Energy loss mechanisms. Pellet compression metrics. Thrust
Chamber: Magnetic nozzle. Shielding. Tritium breeding. Thermal modeling.
Fusion Driver (lasers, particle beams, etc): Heat rejection. Vehicle
Summary: Mass estimates. Vehicle Performance: Interstellar travel required
exhaust velocities at the limit of fusion's capability. Interplanetary
missions are limited by power/weight ratio. Trajectory modeling. Typical
mission profiles. References, including the 1978 report in JBIS, "Project
Daedalus", and several on ICF and driver technology.)
[D71] Bussard, Robert W., "Fusion as Electric Propulsion", Journal of
Propulsion and Power, Vol. 6, No. 5, Sept.-Oct. 1990. (Fusion rocket
engines are analyzed as electric propulsion systems, with propulsion thrust-
power-input-power ratio (the thrust-power "gain" G(t)) much greater than
unity. Gain values of conventional (solar, fission) electric propulsion
systems are always quite small (e.g., G(t)<0.8). With these, "high-thrust"
interplanetary flight is not possible, because system acceleration (a(t))
capabilities are always less than the local gravitational acceleration. In
contrast, gain values 50-100 times higher are found for some fusion
concepts, which offer "high-thrust" flight capability. One performance
example shows a 53.3 day (34.4 powered; 18.9 coast), one-way transit
time with 19% payload for a single-stage Earth/Mars vehicle. Another
shows the potential for high acceleration (a(t)=0.55g(o)) flight in
Earth/moon space.)
58c Electrostatic Confinement
The fusion fuel is confined by a spherical potential well of order 100 kV.
When the fuel reacts, the particles are ejected with energy of order 2 MeV,
so escape the potential well. The potential well is at the focus of a
paraboloidal shell, which reflects the fusion particles to the rear in a narrow
beam (20-30 degree width).
References:
[D72] Bussard, Robert W., "The QED Engine System: Direct Electric
Fusion-Powered Systems for Aerospace Flight Propulsion" by Robert W.
Bussard, EMC2-1190-03, available from Energy/Matter Conversion Corp.,
9100 A. Center Street, Manassas, VA 22110. (This is an introduction to
the application of Bussard's version of the Farnsworth/Hirsch electrostatic
confinement fusion technology to propulsion. 1500<Isp<5000 sec.
Farnsworth/Hirsch demonstrated a 10**10 neutron flux with their device
back in 1969 but it was dropped when panic ensued over the surprising
stability of the Soviet Tokamak. Hirsch, responsible for the panic, has
recently recanted and is back working on QED. -- Jim Bowery)
58d Plasma Mantle Confinement
The fusion fuel is contained in a toroidal/poloidal current pattern, similar to
a Tokamak except all the currents are in the plasma. The current pattern is
surrounded by a plasma sheath which isolates the fuel from a surrounding
working fluid. The fluid provides mechanical compression, which heats the
fuel to fusion ignition. After the fuel burn is completed, the energy
generated heats the working fluid to high temperature, which then goes out
a nozzle producing thrust.
References:
[D73] Koloc, Paul M., "PLASMAKtm Star Power for Energy Intensive
Space Applications", Eighth ANS Topical Meeting on Technology of
Fusion Energy, Fusion Technology , March 1989. (Aneutronic energy
(fusion with little or negligible neutron flux) requires plasma pressures and
stable confinement times larger than can be delivered by current approaches.
If plasma pressures appropriate to burn times on the order of milliseconds
could be achieved in aneutronic fuels, then high power densities and very
compact, realtively clean burning engines for space and other special
applications would be at hand. The PLASMAK* innovation will make this
possible; its unique pressure efficient structure, exceptional stability, fluid-
mechanically compressible Mantle and direct inductive MHD electric power
conversion advantages are described. Peak burn densities of tens of
megawats per cc give it compactness even in the multi-gigawatt electric
output size. Engineering advantages indicate a rapid development schedule
at very modest cost. [I strongly recommend that people take this guy
seriously. Bob Hirsch, the primary proponent of the Tokamak, has recently
declared Koloc's PLASMAK* precursor, the spheromak, to be one of 3
promising fusion technologies that should be pursued rather than Tokamak.
Aside from the preceeding appeal to authority, the PLASMAK* looks like
it finally models ball-lightning with solid MHD physics. -- Jim Bowery])
59 Neutral Particle Beam Thruster
Alternate Names:
Type:
Description: A high energy (order 50 MeV) particle accelerator generates
a proton beam. This beam is neutralized (turned into atoms), then ejected.
The exhaust is moving at a substantial fraction of the speed of light, so
performance is very high. This type of machine was explored under the
SDI program as a way of destroying missiles (with the beam).
Status:
Variations:
References:
60 Antimatter Annihilation
Alternate Names:
Type:
Description: Protons and antiprotons annihilate, producing pions, then
muons, then gamma rays. The charged particles can be acted upon by a
magnetic nozzle. Antimatter provides the highest theoretical energy fuel
(100% matter to energy conversion), although the overhead involved with
storing antimatter may reduce the practical efficiency to a level comparable
to other propulsion methods.
Status:
Variations:
References:
[D74] Forward, Dr. Robert L. "Antiproton Annihilation Propulsion",
AFRPL TR-85-034 from the Air Force Rocket Propulsion Laboratory
(AFRPL/XRX, Stop 24, Edwards Air Force Base, CA 93523-5000). NTIS
AD-A160 734/0 [Quote: Technical study on making, holding, and using
antimatter for near-term (30-50 years) propulsion systems. Excellent
bibliography. Forward is the best-known proponent of antimatter. This
also may be available as UDR-TR-85-55 from the contractor, the University
of Dayton Research Institute, and DTIC AD-A160 from the Defense
Technical Information Center, Defense Logistics Agency, Cameron Station,
Alexandria, VA 22304-6145. And it's also available from the NTIS, with
yet another number.]
[D75] G. D. Nordley, "Application of Antimatter - Electric Power to
Interstellar Propulsion", Journal of the British Interplanetary Society, June
1990.
D.7b External Particle Interaction
61 Magsail
Alternate Names:
Type:
Description: The magsail operates by placing a large superconducting
loop in the solar wind stream. The current loop produces a magnetic field
that deflects the solar wind, producing a reaction force.
Status:
Variations:
References:
62 External Particle Beam
Alternate Names:
Type:
Description: A fixed particle beam source aims it at a target vehicle. The
particles are absorbed or reflected generating thrust at the vehicle.
Status:
Variations:
References:
63 Interstellar Ramjet
Alternate Names: Bussard Ramjet
Type:
Description: Compressing and fusing interstellar hydrogen for
propulsion. Because of the low density of the interstellar medium, an
extraordinarily large scoop is required to get any useful thrust. Performance
is limited by the exhaust velocity of the fusion reaction to a few percent of
the speed of light.
Status:
Variations:
References:
[D76] R. W. Bussard, "Galactic Matter and Interstellar Flight",
Astronautica Acta 6 (1960): 179 - 194.
[D77] A. R. Martin, "The Effects of Drag on Relativistic Spacefight",
JBIS 25 (1972):643-652
[D78] N. H. Langston, "The Erosion of Interstellar Drag Screens", JBIS
26 (1973): 481-484.
[D79] D.P. Whitmire, "Relativistic Spaceflight and the Catalytic Nuclear
Ramjet", Acta Astronautica 2 (1975): 497 - 509.
[D80] C. Powell, "Flight Dynamics of the Ram-Augmented Interstellar
Rocket", JBIS 28 (1975):553-562
[D81] D.P. Whitmire and A.A. Jackson, "Laser Powered Interstellar
Ramjet", JBIS 30 (1977):223 - 226.
[D82] G. L. Matloff and A. J. Fennelly, "Interstellar Applications and
Limitations of Several Electrostatic/Electromagnetic Ion Collection
Techniques", JBIS 30 (1977):213-222
64 Interstellar Scramjet
Alternate Names:
Type:
Description: Similar to the interstellar ramjet, the interstellar medium is
compressed to fusion density and temperature. In this concept it is only
compressed laterally, then re-expanded against a nozzle. Incredible vehicle
sizes and lengths are required to reach fusion conditions, but speed may
reach a substantial fraction of the speed of light.
Status:
Variations:
References:
--
Dani Eder/Rt 1 Box 188-2/Athens AL 35611/(205)232-7467
|
| 311.31 | Canonical List Version 0.75 - Part 4 of 4 | MTWAIN::KLAES | Houston, Tranquility Base here... | Tue Jul 05 1994 15:39 | 549 |
| Article: 2393
From: [email protected] (Dani Eder)
Newsgroups: sci.space.tech
Subject: Canonical List of Space Transport Methods (4/4)
Date: 1 Jul 94 18:18:57 GMT
Organization: Boeing AI Center, Huntsville, AL
D.8 Photon Engines
D.8a Photon Sails
65 Solar Sail
Alternate Names: Lightsails
Type:
Description: Sunlight reflecting off a large area sail produces force
because momentum of photons is reversed by refelection. Force is
(1+r)(E/c) for normal reflection, where r is the reflectivity of the sail, E is
the incident power, and c is the speed of light. At the distance of the Earth
from the Sun, the incident power is 1370 MW per square kilometer. This
produces about 8 Newtons/square kilometer for high-reflectivity sails.
Status:
Variations:
References:
[D83] Marchal, C. "Solar Sails and the ARSAT Satellite - Scientific
Applications and Techniques", L'Aeronautique et L'Astronautique, no 127,
pp 53-7, 1987.
[D84] Louis Friedman, Starsailing. Solar Sails and Interstellar Travel. ,
Wiley, New York, 1988, 146 pp., paper $9.95.
66 Laser Lightsail
Alternate Names:
Type:
Description: Laser photons are reflected off sail material. Reflection of
photons reverses their momentum vectors' component which is normal to
the sail. By conservation law, the sail gains momentum. Laser sails can
have higher performance than solar sails because the laser beam intensity is
not limited like the brightness of the sun.
Status:
Variations:
References:
[D85] Forward, Robert L., "Roundtrip Interstellar Travel Using Laser-
Pushed Lightsails" Journal of Spacecraft and Rockets , vol. 21, pp. 187-
95, Jan.-Feb. 1984
67 Microwave Sail
Alternate Names: Starwisp
Type:
Description:
Microwaves are reflected off very thin, open mesh. Momentum change of
photons bouncing off of mesh provides thrust. Because an open mesh of
thin wires can have a very low weight, in theory this propulsion method can
give high accelerations.
Status:
Variations:
References:
D.8b Photon Rockets
68 Thermal Photon Reflector
Alternate Names:
Type:
Description: A heat generating device, such as a nuclear reactor, is at the
focus of a paraboloidal reflector. The thermal photons are focussed into a
near parallel beam, which propells the vehicle. Another high-energy source
is a matter-antimatter reaction, which is absorbed by a blanket of heavy
metals and converted to heat.
Status:
Variations:
References:
69 Quantum Black Hole Generator
Alternate Names:
Type:
Description: In theory, a quantum black hole will emit particles as if it
were a black body of a certain temperature. If new matter is added to the
black hole at a rate sufficient to offset the emission losses, effectively 100%
conversion of matter to energy can be achieved. Black holes, quantum or
otherwise, are very massive, so the utility of such for propulsion is
questionable for anything smaller than an asteroid sized spaceship.
Status:
Variations:
References:
70 Gamma Ray Thruster
Alternate Names:
Type:
Description:
Gamma rays produced by antimatter annihilation behind vehicle can be
absorbed by a thick layer of heavy metals. Momentum of gamma ray
photons produces thrust.
Status:
Variations:
References:
D.9 External Interactions
71 Ionospheric Current Loop
Alternate Names: Electrodynamic Engine
Type:
Description: A current-carrying wire in a planetary magnetic field feels an
IxB force. The current loop is closed through an ionosphere. The wire
accelerates in one direction (pulling a vehicle along), and the ionosphere
accelerates in the other direction. Per unit of power input a current loop
thruster produces more thrust than an ion engine. No propellant is
consumed directly, although some material is consumed to produce a
plasma that enables good electrical contact with the ionosphere. Effectively
this gives a specific impulse in the 25,000 range.
Status:
Variations:
References:
[D86] Belcher, J. W. "The Jupiter-Io Connection: an Alfven Engine in
Space", Science vol 238 no 4824 pp 170-6, 9 Oct 1987.
72 Gravity Assist
Alternate Names: Planetary Flyby, Celestial Billiards
Type:
Description: Momentum exchange between planetary body and
vehicle allow changing direction, and velocity in other reference frames.
Status:
Variations:
References:
73 Dumb-Waiter
Alternate Names:
Type:
Description: Matter falling down a gravity well can be an energy source to
power payloads going up the gravity well.
Status:
Variations:
References:
74 Aerobrake
Alternate Names:
Type:
Description: Using drag against a planetary atmosphere to slow down.
Status:
Variations:
74a Single pass aerobrake
74b Multi-pass aerobrake
References:
75 Rheobrake
Alternate Names:
Type:
Description: Using drag against a planetary surface to slow down. For
example, imagine a rail made of cast basalt on the lunar surface. It is laid
level to the ground, and is shaped like a conventional steel railroad rail. A
landing vehicle is in a low grazing orbit. It aligns with the rail, just above
it, then exends some clamps over the rail. By applying clamping pressure,
the vehicle can brake from lunar orbit to a stop. Obviously the brake will be
dissipating a lot of heat, and will therefore have to be made of high
temperature material such as graphite.
Another approach is to have a 'runway' which is a smoothed area on the
lunar surface. The arriving vehicle slows down to below orbital speed, then
gravity puts it down on the runway, and friction on the bottom of the
vehicle slows it down.
Status:
Variations:
References:
D.10 Comparisons Among Methods
Propulsion concepts can be sorted in various ways. One is by performance.
Measures of performance include specific impulse and thrust to weight
ratio. Another sorting is by technology maturity. It is hoped in a later
verion of this survey that these types of sortings or rankings can be
provided.
Section E: Space Engineering Methods
[This section is still very preliminary]
E.1 Methods of Finding Resources
E.2 Inventory of Resources
E.2.a Matter resources in the Solar System
The Sun.
[mass, composition]
The Gas Giants.
Jupiter
Saturn
Uranus
Neptune
Planets and Satellites With Atmospheres
Venus
Earth
Mars
Titan
Triton
Larger Airless Bodies
Small Bodies
Small Moons
Asteroids
Comets
Particles
Rings
Interplanetary dust
Gas and solar wind
E.2.b Energy resources in the Solar System
The Sun.
[hydrogen to helium fusion energy]
[other nuclear reactions]
[stored thermal energy of sun]
[gravitational collapse energy]
The Planets.
[latent heat of formation - Jupiter]
[nuclear decay]
[fusion energy of hydrogen]
[non-equilibrium chemistry(fossil fuels)]
[stored thermal energy]
[gravitational potential of satellites & planets vs. Sun.]
E.2.c Matter resources in the Galaxy
The mass of the Galaxy
Dark Matter
E.2.d Energy resources in the Galaxy
Power output
Energy reserves
[Fusion]
[Gravity collapse]
E.3 Methods of Extracting Resources
Most of the visible mass in the Universe is inconveniently located in the
interior of large bodies, where it hard to get to. In fact spheres, the shape
which many large objects approximate, have the least surface area for a
given volume. In other words, the ratio of relatively inaccessible material in
the interior to accessible material on the surface is a maximum. Another
problem is that useful metals, such as Iron, tend to collect in the center
of planets, where pressures and temperatures are both very high.
To obtain sufficient raw materials for large projects, dismantling of large
bodies may be required. This can be considered mining in the limit of
mining the entire body. This section lists mining/dismantling methods
which are not covered by conventional mining processes followed by
launch using one of the methods in section D.
E.3.a Extracting Matter Resources from Sub-Planetary Bodies
E.3.b Extracting Matter Resources from Terrestrial Planets
E.3.c Extracting Matter Resources from Jovian Planets
76 Mechanical Disruption
This is the brute-force method. One approach involves directing a large
body at high speed at the planet. The other approach is to collect deuterium
and helium-3 and use them to make a really big thermonuclear device.
77 Spin-Up to Orbital Speed
This method involves increasing the already fast rotation rate of the planet
until the equator is at orbital velocity. Removal of material from the equator
to orbit becomes a simple matter. There are a number of techniques for
increasing the rotation rate:
Spin-up techniques
Differential light pressure
Aerobraking momentum transfer
Repeat maneuvers
High speed angular momentum deposition
Magnetic coupling
Gravity coupling (using subsynchronous satellites to raise tides)
Reaction motor
78 Boiloff
This method involves reversing the way the planet formed in the first place.
Jovian planets form by collapse of a gas cloud as it radiates away energy.
Our largest planet, Jupiter, is apparently still radiating away excess heat
today, after 5 billion years. If excess solar energy is directed at a jovian
planet, it will heat up and reverse this process.
79 Scoop Mining
E.3.d Extracting Matter Resources from Stars
E.4 Uses for Resources
E.4.a Matter Resources
80 On-site fuel extraction
Alternate Names:
Type:
Description: If you don't have to bring it with you, your mass ratio
improves.
Status:
Variations:
References:
[E1] Ramohalli, K.; Ash, R.; Dowler, W.; French, J. "Some Aspects of
Space Propulsion with Extraterrestrial Resources", Journal of Spacecraft
and Rockets v 24 no 3 pp 236-44, 1987.
81 Comet consumption en-route
Alternate Names:
Type:
Description: Interstellar missions require a lot of propellant. In this
concept, several comets are intercepted by a propulsion unit that comes from
the 'mother ship'. The propulsion unit consumes part of the comet to bring
the rest of the comet up to speed, and then uses the remainder to further
accelerate the mother ship. This allows somewhat better velocities than
starting with all the fuel onboard at the start of the mission.
Status:
Variations:
References:
82 Solar Sails from FeNi Asteroid
Alternate Names:
Type:
Description: To recover large amounts of material from the asteroids,
Iron-nickel alloy can be rolled into foil, and then used to make solar sails.
If what you want to extract is steel, then it sails itself back to where
you want it. If you want some other material, you can make large amounts
of sail area fairly simply (you need the functions of a rolling mill - a way to
heat the material and a way to force it between two rollers to make thin
sheets. Steel is not as light as aluminum-magnesium alloy as a sail material,
and it is not as good a reflector, but it is readily available in large
quantities in asteroids and does not need a lot of processing to make into a
useable form.
Status:
Variations:
References:
83 Structural materials
Alternate Names:
Type:
Description: A variety of structural materials can be made from local
materials in space, thus reducing the amount of material that has to be
brought from Earth. Examples include Iron-nickel from that type of
asteroid, and from meteoroid dust on the lunar surface (which only require
magnetic separation), and cast or sintered rock, using solar heating to melt
random rock into useful shapes.
Status:
Variations:
References:
E.4.b Energy Resources
84 Solar Power Stations
Alternate Names:
Type:
Description: Sunlight in space is not affected by night, clouds, or
atmospheric absorbtion. A large solar power plant can produce power, then
send it elsewhere using an efficient microwave beam. Example uses are to
deliver power to Earth from orbit, and to deliver power to a Mars lander
using the transit vehicle solar array.
Status:
Variations:
84a Planet Surface
84b Orbiting
84c Photovoltaic
84d Solar-Thermal
References:
85 Atmospheric Laser
Alternate Names:
Type:
Description: Lasing medium is the atmosphere or ionosphere of a planet
or satellite.
Status:
Variations:
References:
E.2 Methods of Reducing Payload Mass/Volume
86 Closed Life Support
By recycling part or all of the materials used to sustain life, the amount of
stored supplies or newly delivered supplies can be reduced. If coupled with
local extraction of life support supplies, can reduce the amount of extraction
required. Water, air, and food are the principal items that can be recycled.
87 Inflatable/Erectable Structures
For launch from a planet it may be useful to collapse a structure into a small
package. Once on location it is inflated or assembled to form the finished
object.
88 Recycling upper stages
A conventional rocket takes the final stage, along with the payload, into
orbit. By re-fueling the stage, or by converting the stage tanks and
structures to another use (such as an occupied pressurized module), some
payload weight and volume is saved.
89 Fabricators/Replicators
A general-purpose factory system can make a wide variety of products,
including copies of most or all of it's own parts. Then a small seed factory
can grow to a large production capacity with a high output product to intial
payload mass ratio.
90 Nanofax Transmitter
The energy to transmit the description of an object to another star, even at an
atom by atom level, is about a million times less than the energy to
physically move the object from one star to another. Thus, after the first
probe sets up a receiving/replication station at the other star, other objects
are more efficiently scanned, transmitted, and reconstructed at the receiving
end. Using atomic scale technology (nanotech) it may be possible to send
people this way. The subjective time to travel at the speed of light is zero.
Section F: General References
References in this section contain data about two or more propulsion
concepts:
[F1] Koelle, Heinz Hermann, ed., Handbook of Astronautical
Engineering, New York, McGraw-Hill, 1961. This is an excellent
comprehensive reference handbook representing the state of the art as of
1961. Has a chapter covering nuclear, electric, and solar-thermal
propulsion.
[F2] Loeb, H. W. "Electric Propulsion Technology Status and
Development Plans - European Programs (Space Vehicles)", J. Spacecraft
and Rockets , vol 11 no 12 pp 821-8, Dec. 1974.
[F3] Parkash, D. M. "Electric Propulsion for Space Missions", Electr.
India vol 19 no 7 pp 5-15, 15 April 1979.
[F4] Kunz, K. E. "Orbit Transfer Propulsion and Large Space Systems",
J. Spacecraft and Rockets vol 17 no 6 pp 495-500, Nov.-Dec. 1980.
[F5] Diesposti, R. S.; Pelouch, J. J. "Performance and
EconomicJComparison of Externally Energized vs Chemically Energized
Space Propulsion", AIAA paper number 81-0703 presented at 15th
International Electric Propulsion Conference, Las Vegas, Nevada, 21-23
June 1981.
[F6] Andrews, Dr. Dana G, ed. Advanced Propulsion Systems
Concepts for Orbital Tansfer: Final Report, Boeing document D180-
26680 produced under NASA contract NAS8-33935.
[F7] Poeschel, R. L. "Comparison of Electric Propulsion
Technologies",J AIAA paper number 82-1243 presented at
AIAA/SAE/ASME 18th Joint Propulsion Conference, Cleveland, Ohio, 21-
23 June 1982.
[F8] Jones, R. M.; Kaplan, D. I.; Nock, K. T. "Electric Propulsion
Systems for Space Stations" AIAA/SAE/ASME 19th Joint Propulsion
Conference, AIAA paper number 83-1208, 1983.
[F9] Forward, Robert "Alternate Propulsion Energy Sources", AFPRL
TR-83-067. (NTIS AD-B088 771/1) Dec 1983, 138p. Keywords:
Propulsion energy, metastable helium, free-radical hydrogen, solar pumped
(sic) plasmas, antiproton annihiliation, ionospheric lasers, solar sails,
perforated sails, microwave sails, quantum fluctuations, antimatter rockets
"It's a wide, if not deep, look at exotic energy sources which might be
useful for space propulsion. It also considers various kinds of laser
propulsion, metallic hydrogen, tethers, and unconventional nuclear
propulsion. The bibliographic information, pointing to the research on all
this stuff, belongs on every daydreamer's shelf."
[F10] Jones, R. M. "Space Supertankers: Electric Propulsion Systems for
the Transportation of Extraterrestrial Resources" AIAA/SAE/ASME 20th
Joint Propulsion Conference, AIAA paper number 84-1323, 1984.
[F11] Wang, S.-Y.; Staiger P. J. "Primary Propulsion of Electro-Thermal,
Ion and Chemical Systems for Space Based Radar Orbit Transfer",
AIAA/SAE/ASME/ASEE 21st Joint Propulsion Conference, AIAA paper
number 85-1477, 1985.
[F12] Faughnan, Barbara (ed.); Maryniak, Gregg (ed.) "Space
Manufacturing 5: Engineering with Lunar and Asteroidal Materials",
proceedings of the 7th Princeton/AIAA/SSI Conference, Princeton, New
Jersey, 8-11 May 1985.
[F13] Phillips, P. G.; Redd, B. "Propulsion Options for Manned Missions
to the Moon and Mars", in Aerospace Century XXI (see reference F12).
[F14] Morgenthaler, G. W.; Tobiska, W. K. "Aerospace Century
XXI: Space Flight Technologies", Proceedings of the 33rd Annual AAS
International Conference, Boulder, Colorado, 26-29 Oct. 1986. Published
as Advances in the Astronautical Sciences, vol 64, pt 2, 1987.
[F15] Matloff, G. L. "Electric Propulsion and Interstellar Flight", 19th
International Electric Propulsion Conference, Colorado Springs, Colorado,
11 May 1987.
[F16] Korobeinikov, V. P. "On the Use of Solar Energy for the
Acceleration of Bodies to Cosmic Velocities", Acta Astronautica, v 15 no 11
p 937-40, November 1987.
[F17] Kerrebrock, J. L "Report of the National Commission on Space-
One Commissioner's View", in Aerospace Century XXI (see reference
[F14]).
[F18] Harvego, E. A.; Sulmeisters, T. K. "A Comparison of Propulsion
Systems for Potential Space Mission Applications", ASME Winter
Meeting, Boston, Massachusetts, 13 December 1987, 1987.
[F19] Forward, R. L. "Exotic Propulsion in the 21st Century", in
Aerospace Century XXI (see reference [F14]).
[F20] Forward, R. L. "Advanced Space Propulsion Study - Antiproton
and Beamed Power Propulsion", Final Report, 1 May 1986 - 30 Jun
1987, Hughes Research Laboratories, report AFAL-TR-87-070,
1987.DefenseTechnical Information Center #AD-A189 218. National
Technical Information Service # AD-A189 218/1 PC A10/MF A01
[Quote: , goes into detail on beamed power systems including " 1) pellet,
microwave, and laser beamed power systems for intersteller transport; 2) a
design for a near-relativistic laser-pushed lightsail using near-term laser
technology; 3) a survey of laser thermal propulsion, tether transportation
systems, antiproton annihilation propulsion, exotic applications of solar
sails, and laser-pushed interstellar lightsails; 4) the status of antiproton
annihilation propulsion as of 1986; and 5) the prospects for obtaining
antimatter ions heavier than antiprotons." Again, there is an extensive
bibliography.]
[F21] Byers, David C.; Wasel, Robert A. "NASA Electric
Propulsion Program", NASA Technical Memorandum 89856, May 1987.
[F22] Forward, Dr. Robert L., Future Magic., Avon, 1988. ISBN 0-380-
89814-4. "Nontechnical discussion of tethers, antimatter, gravity control,
and even futher-out topics."
[F23] Mallove, Eugene F. and Matloff, Gregory L., The Starflight
Handbook: A Pioneer's Guide To Interstellar Travel, 1989. (semi-technical
introduction to interstellar flight.)
--
Dani Eder/Rt 1 Box 188-2/Athens AL 35611/(205)232-7467
|
| 311.32 | Orbital Loop and Electrotube | MTWAIN::KLAES | No Guts, No Galaxy | Wed Aug 10 1994 18:14 | 152 |
| Article: 2942
From: Andrew Nowicki <[email protected]>
Newsgroups: sci.space.tech
Subject: Cheap Access to Space
Date: Wed, 10 Aug 94 00:37:16 -0500
Organization: Delphi ([email protected] email, 800-695-4005 voice)
Let's talk about cheap transportation from the Earth to low Earth orbit.
This message is my subjective evaluation of the published ideas.
1. Konstantin Tsiolkovsky was the first author who proposed the use
of chemical rockets for space transportation. Realizing the enormous cost of
the rockets, he suggested an alternative method of transportation -- an
equatorial tower extending all the way to the geostationary orbit. The idea
does not make sense because it requires structural materials of
extraordinary strength. The same is true of a tether extending beyond the
geostationary orbit. [references: Jerome Pearson, "The orbital tower: a
spacecraft launcher using the Earth's rotational energy," Acta Astronautica,
vol. 2(9-10) pages 785-99, Sept.-Oct. 1975; John Isaacs at al, "Satellite
Elongation into a True Sky-Hook," Science, vol. 151, pages 682-683, February
11, 1966, also vol. 152, page 800 and vol. 158 pages 946-947]
2. An orbiting elevator picks up payloads brought by sounding
rockets, lifts them to a higher orbit, and drops them off. Electrodynamic
tethers generate thrust. When the elevator is in a state of stable
equilibrium, it is curved and its bottom is ahead of its top. An elevator
flying at 5 km/s will reduce the cost of transportation by half. A vertical
tether described by Zubrin is subject to low stress, but its dynamic
stability is questionable. [reference: Robert Zubrin, "The Hypersonic
Skyhook," Analog Science Fiction and Fact, Sept. 93, vol. 113(11) pp. 60-70]
3. Rotating tethers (e.g., non-synchronous orbital skyhook) require
materials of extraordinary strength and are severely perturbed by gravity.
[reference: Hans Moravec, "A Non-Synchronous Orbital Skyhook," Journal of
the Astronautical Sciences, vol. 25(4), pages 307-322 Oct.-Dec. 1977]
4. Payloads can be accelerated to the orbital velocity by a variety
of terrestrial devices including light gas gun, ram accelerator, railgun and
coilgun (mass driver). The payloads are launched into the same equatorial
orbit so that they can be easily collected. Superconductors cannot be used
in the guns because variable magnetic field destroys superconductivity.
The ram accelerator is a tube filled with a mixture of methane, nitrogen
and oxygen. A projectile fired into the tube ignites the mixture which burns
just behind the projectile. It is not clear if the ram accelerator can
achieve the orbital velocity.
The railgun accelerates the projectile by the Lorentz force. The force is
produced by interaction between electric current flowing across the
projectile and a static magnetic field surrounding the projectile.
The coilgun consists of a multitude of coaxial coils generating strong
magnetic field when the projectile passes through the coil. The field
interacts with a current flowing in a coil attached to the projectile.
The projectile will reenter the atmosphere unless its orbit is made more
circular by space borne means. There are 2 methods of changing the orbit:
apogee rocket and slingsat. The apogee rocket modifies the orbit when the
projectile reaches its apogee. The slingsat is similar to the skyhook
described by Moravec. It is a short yet massive tether rotating about its
center of mass and orbiting the Earth. The slingsat captures the projectiles
and releases them later into a more circular orbit. The projectiles are
guided to the slingsat by chemical rockets.
If the gun is located on the ground, the projectile has to be fired at a
steep angle in order to minimize aerodynamic drag. The steep angle calls for
a massive apogee rocket. The rocket is expensive because it has to withstand
extreme acceleration of the gun.
The apogee rocket makes economic sense when a massive payload is gently
accelerated in a nearly horizontal direction (10 deg.) by a device suspended
on balloons at the altitude of at least 20 km. The railgun and coilgun
require power supply which is too heavy for the balloons. The only practical
system is a long (e.g., 10 km) light gas gun suspended on balloons.
[references: Jerome Pearson, "Low-Cost Launch System and Orbital Fuel
Depot," Acta Astronautica, vol. 19(4), pages 315-320, 1989; John W. Hunter
and Rod A. Hyde, "A Light Gas Gun System for Launching Building Material
into Low Earth Orbit," AIAA Paper 89-2439, July 1989]
5. Laser propulsion is a rocket propelled by hydrogen plasma.
Hydrogen is heated to the plasma state by a remote laser. A payload of 1 ton
requires laser output of 1 GW. Such a laser would cost about $100 billion.
As the laser beam penetrates the atmosphere, it may be absorbed by clouds
and distorted by thermal blooming. Plasma is unstable and may overheat the
spacecraft. [reference: Mitat A. Birkan, "Laser Propulsion: Research
Status and Needs," vol. 8(2), pages 354-360, March-April 1992]
6. The space shuttle requires lots of maintenance and repair
because it is exposed to hot, corrosive gasses. A reusable nuclear rocket
propelled by warm (1000 K) hydrogen would be more durable and therefore more
economical. Safety considerations confine the nuclear rocket to the
Antarctic, which implies that it can be used as the first stage rocket only.
7. Scramjets are exposed to the same corrosive environment that
makes chemical rockets prohibitively expensive. At high velocities specific
impulse of scramjets is about the same as that of chemical rockets.
[reference: Terry D. Kasten, "NASP: Expanding Space Launch Opportunities,"
Aerospace Engineering, vol. 11(11), pages 15-17, Nov. 1991]
8. Cartoonist Rube Goldberg inspired contraptions which either
weigh more than 1 million tons (design rule RG1) or fail catastrophically
when a single component malfunctions (design rule RG2). Examples:
Orbital ring (RG1). [reference: Paul Birch, "Orbital Ring Systems and
Jacob's Ladders - I," Journ.Brit.Interplan.Soc., vol. 35, pp. 475-497, 1982]
Launch loop (RG2). [reference: Keith H. Lofstrom, "The launch loop - a low
cost Earth-to-high orbit launch system," AIAA Paper 85-1368, 1985]
Maglev train riding on a 300 km long, segmented rail suspended on
balloons (RG2). The segments have to be kept within one centimeter of
the straight line by propellers reacting to every gust of wind.
Tower suspended by a fountain of magnetic projectiles (RG2).
9. I have conceived two methods of transportation: orbital loop and
electrotube. Both devices operate in a low Earth orbit. A payload vehicle
carries payloads from the Earth to the orbital loop. The vehicle is
transported to the loop by either a long cannon, or a sounding rocket, or a
supersonic plane. A nuclear rocket propelled by warm (1000 K) steam is the
cheapest means of transporting fragile cargo to the loop. The payload
vehicle has no moving parts; it is a cylindrical container coated with
silicon rubber (e.g., Dow Corning 3-6077 RTV). The rubber protects the
vehicle from heat and vibration. After entering the ionosphere the vehicle
rides inside a long tube attached to the loop. The rubber coating is ablated
by ionospheric gases present inside the tube, and by sporadic contact with
the tube. Gaseous products of ablation act as a lubricant between the
vehicle and the tube. They also generate aerodynamic drag that transfers
momentum from the tube to the vehicle. When the vehicle has attained the
orbital velocity, it drops off, and is carried to its final destination by a
variety of economical, low-thrust propulsion techniques.
The orbital loop is an endless tether interspersed with solar-powered
winches. As the loop follows its elliptic orbit, its velocity and tension
undergo periodic changes, not unlike those of a pendulum. These periodic
changes make it possible to restore orbital energy of the loop without the
use of propellants. The winches exert a periodic force on the loop which is
synchronized with the orbital movement of the loop. Much like a child riding
in a swing, the periodic force replenishes the orbital energy of the loop.
The major difference between the electrotube and the orbital loop is that
the electrotube generates thrust with electromagnetic tethers. Both devices
can steer themselves toward incoming payload vehicle with the help of
articulated wings interacting with the ionosphere. An orbital loop having
steel tethers can carry its own mass into a low orbit in about 3 months. The
electrotube can carry the same amount of cargo, but it is less durable due
to intense ionospheric oxygen erosion. The electrotube is a precursor of
the orbital loop; it carries small segments of the orbital loop into space
where they are assembled by remote manipulators. I guess that the
electrotube would cost as much as communications satellites, i.e., $10,000
per kilogram. The minimum mass of the electrotube is about 10 tons, while
the minimum mass of the orbital loop is about 1000 tons.
The orbital loop is an economical means of transportation because it has
a simple design, uses little consumables (mostly rubber), and is fail-safe.
The loop can function, albeit at a low efficiency, even if half of its
winches and tube segments are out of order. Since the loop consists of
thousands of identical segments, economy of scale will reduce the cost. It
is conceivable that a loop fitted with a 100 km long tube will be 2 orders
of magnitude more durable and more economical than chemical rockets.
[references: Andrew Nowicki, "Diversity," The Trumpeter, vol. 10(2),
pages 65-68, Spring 1993; Andrew Nowicki, "Orbital Loop" not published yet]
[email protected]
|
| 311.33 | Spacetime Hypersurfing? | MTWAIN::KLAES | No Guts, No Galaxy | Wed Sep 14 1994 19:17 | 78 |
| Article: 3441
From: [email protected] (William L. Goffe)
Newsgroups: sci.space.tech
Subject: Warp Drive?
Date: 12 Sep 1994 10:20:13 -0500
Organization: University of Southern Mississippi
I recently came across an interesting article in the Oct. 1994 issue
of the _American Scientist_. On pp. 422-3, there is a a short article
by Michael Szpir titled "Spacetime Hypersurfing?" It describes a paper
by Miguel Alcubierre, a physicist a the University of Wales in
Cardiff, in the May issue of _Classical and Quantum Gravity_. Our
library doesn't get it, so I couldn't read the orginal (like I could
read it anyway).
Alcubierre suggests that one might be able to distort spacetime in the
following way: A region of space in front of the ship is contracted,
and behind is expanded, so a ship would in effect travel by surfing on
this distortion in spacetime faster than the speed of light to an
outside observer.
This would seemingly violate special relativity, but the article
explains that inside the distortion, the speed of light would would be
unchanged. In other words, light in the distortion would travel along
with the distortion, which would move faster than light outside.
In addition, the ship would experience no acceleration, and there
would be no time dilation for the ship.
The item that makes this appear to be a bit far off is that it
requires exotic matter, which has a negative energy density. Exotic
matter is gravitationally repelled by "normal" matter. However, it is
thought that exotic matter might actually exist, or could be made. In
fact, Alcubierre came up with the idea from the concept the theory of
an inflationary universe, which uses exotic matter.
I find it a bit interesting that this hasn't appeared in the rest of
the popular press. I guess Stephen Jay Gould was correct in his book
_Wonderful Life_ when he said that science journalists only read a
subset of journals like _Nature_ and _Science_ for their ideas.
Clearly, _Classical and Quantum Gravity_ isn't on many of their
reading lists (nor on mine, to be honest).
Finally, as a sanity check, I was pleased to note that this article
didn't appear in the April issue.
Obviously, given my sig, questions on this should go elsewhere.
.---. Bill Goffe [email protected]
( | Dept. of Econ. and International Business office: (601) 266-4484
)__*| University of Southern Mississippi fax: (601) 266-4920
(_| Southern Station, Box 5072
Hattiesburg, MS 39406-5072
Article: 3463
From: [email protected] (John F Carr)
Newsgroups: sci.space.tech
Subject: Re: Warp Drive?
Date: 13 Sep 1994 22:46:42 GMT
Organization: Massachusetts Institute of Technology
In article <[email protected]>,
William L. Goffe <[email protected]> wrote:
I read the article. It didn't talk about practical applications, but the
concept doesn't sound useful for a spacecraft drive. Because gravity waves
travel at lightspeed a spacecraft won't be able to push itself forward
faster than light using fields it generates. However, it might be useful
as a sort of interstellar cable car system, with prepositioned devices to
generate the space distortion (timers can be used to move the distortion
according to predetermined schedule) and drag the spacecraft along its route.
If you have a lot of exotic matter, you may be able to do something more
interesting than a warp drive. Maybe you could make a stable wormhole.
--
John Carr ([email protected])
|
| 311.34 | Old news to Trekkies. | KAOM25::WALL | | Wed Oct 26 1994 12:27 | 7 |
| re -1
If you had watched enough Star Trek this would sound very familiar...
right down to the "exotic" matter.
Rob Wall
Kanata Manufacturing Engineering Support 621-4407
|