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| Title: | Space Exploration |
| Notice: | Shuttle launch schedules, see Note 6 |
| Moderator: | PRAGMA::GRIFFIN |
|
| Created: | Mon Feb 17 1986 |
| Last Modified: | Thu Jun 05 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 974 |
| Total number of notes: | 18843 |
537.0. "Japan's LACE Spaceplane" by RENOIR::KLAES (N = R*fgfpneflfifaL) Tue May 30 1989 17:27
Date: 24 May 89 07:01:06 GMT
From: [email protected] (Larry Smith)
Subject: Spaceplane Propulsion (LACE)
In article <[email protected]> [email protected]
(John McKernan) writes:
^^Air liquification is an approach the Japanese are taking in their aerospace
^^plane project. The whole point of such a plane is to drastically increase
^^ ...
In article <[email protected]> [email protected] (James
Symon) writes:
^^net, high mach numbers bring on very tricky engine issues. Couldn't a
^^hybrid be built in which oxidizer injection is gradually increased as
^^altitude and speed begin to cause combustion problems? Eventually the
^^intake ports are closed and the motors are straight liquid fuel rocket
^^ ...
Following is some information from one of the Japanese papers
presented at the First International Conference on Hypersonic Flight
In The 21st Century. This conference was held Sept 20-23, 1988 at the
University of North Dakota. The conference was attended by almost all
significant international SSTO (Single Stage To Orbit) projects. The
exception was the Russians, who were invited and said that Mr. A.
Tupolev would give a paper, but he did not appear. When asked later
why he didn't appear, he replied: "The time for talk has passed. Now
it is time to work!" The conference was co-sponsored by: NASA, ESA,
AIAA, IEEE/AESS, NAL/STRG, AAS.
The paper is entitled: "A Concept of LACE For Space Plane To The Earth Orbit"
Authors: Hiroyuki Hirakoso, Teruyuki Aoki
Mitsubishi Heavy Industries Ltd.
Engine Engineering Dept.
Tetsuichi Ito
National Space Development Agency of Japan
The paper made the following justification for air breathing engines:
To successfully design a reusable space plane that can carry
payloads into orbit, its important to decrease structural
weight and increase Isp (Specific Impulse). Isp is the more
important of the two to increase. Currently, the most practical
way to significantly raise Isp, is with a Air Breathing Engine
(ABE).
(The equation for rocket Isp is (Thrust / Propellant Weight Flow Rate).
The Isp equation must be different for ABEs, because of ram
pressure increases to thrust (depending on ram engine type).
A rocket has momentum thrust and pressure thrust components
only, in its thrust term. The propellant weight flow rate
for a ABE probably only counts onboard propellant as well.)
Performance, as measured by Isp, of LOX/LH2
(Liquid Oxygen/Liquid Hydrogen) rocket engines is reaching its
theoretical limit.
60%-70% of carried propellants in a LOX/LH2 rocket, are used to
attain an altitude of 40KM.
The paper made the following justification for a LACE air breathing engine:
Air above 40KM (~131,000 ft.) is too thin to sustain a Air Breathing
Engine.
LACE can perform the total mission. It can accelerate from zero
velocity on a runway/launch pad, to Mach 10 at an altitude of 40KM,
to orbital velocity via traditional rocket propulsion in the upper
atmosphere.
LACE is a derivative of the rocket engine and inherits many rocket
engine characteristics.
LACE represents a lower development risk in that it builds on the same
base of cryogenic technology used for current LOX/LH2 rockets.
The principle behind a LACE engine is the liquifying of air via a
cryogenic propellant. LH2 is used as the cryogenic because it has a
boiling point (20 deg. K) below that of oxygen (90 deg. K) which makes
up roughly 21% of air. LH2 is circulated through a number of cooling
tubes (the Japanese have a experimental heat exchanger for a 10 ton
thrust LACE with 10,000 cooling tubes), and intake air is circulated
through the cooling tube structure. As a result of this, some of the
air is liquified and pools, I assume, at the bottom of the heat exchanger.
The circulated LH2, heats up, and becomes H2 gas. The hydrogen and liquid
air then eventually mix in the rocket's combustion chamber.
Now, as you can see, the weight of the heat exchanger is a key factor.
They published a table with rough-estimate, engine weight components, for a
different, projected 100 ton thrust class LACE engine. There was supporting
material for their estimation of a sub 1000 Kg Heat Exchanger. It looks
like they have done allot of work on this.
Air Intake: 200 Kg
Air Liquifier: 900 Kg
Liquid Air Spray: 200 Kg
Rocket Engine: 1600 Kg
Accessories: 100 Kg
-------------------------
Total: 3000 Kg
The total air-handling mechanism (Intake, Liquifier, Air Spray) is just
under the weight of the rocket itself (there may be a air compressor
with a 10 to 1 pressure ratio as well, see LACE techniques below).
The paper also had block diagrams of 7 different LACE engine techniques.
These techniques describe different ways in which liquification can be
performed and how it would be integrated with the rocket engine.
They also presented two engine schematics. One for a vertical launch
LACE where 6 - 100 ton thrust LACE engines, with their tankage,
replace the Solid Rocket Boosters of their H2 rocket. The Isp of the
vertical launch LACE was 700 sec (at sea level static). 700 sec is a
LOW Isp for a ABE. The reason this one is so low, is that this LACE
still burns LOX, even in Air Breathing Mode, but at a lower mixture
ratio than a standard LOX/LH2 engine. The liquid air augments the LOX
in this engine. They say the Isp is still nearly double a standard
LOX/LH2 engine (I thought LOX/LH2 engines have Isp's of ~450). They
claim they can triple their payload with this technique!!
Thrust/Weight was 33/1. The Mixture ratio for a LACE is expressed as
the Liquification Ratio (LR). For a liquid rocket, mixture ratio is
Oxidizer Flow Rate/Fuel Flow Rate, and for a typical Booster LOX/LH2
engine, mixture ratio is in the 3-4 range (I think). For a LACE, LR is
Air Flow Rate/Fuel Flow Rate. The LR for this vertical launch LACE
engine is 6.28/1.0. They intend to build vertical launch LACE boosters
as soon as they're feasable. The other LACE schematic was for a Space
Plane. It had an Isp of 2600 sec, and a LR of 10.37/1.0. Both of their
engine designs use several of the following techniques at the same time.
Basic LACE:
[ LH2 Tank ]
|
v
[ LH2 Pump ]
|
|
------------ v __/
<Air Intake|->-[Heat Exchanger]-->---[liquid air pump]-->---|__ Thrust ->
------------ | ^\
| |
------ gaseous H2 ------------------------
Comments:
This is the simplest form of LACE. Only LH2 is used for liquification.
The LR is limited to around 4, and therefore hydrogen rich.
A lower Isp is thus attained.
Oxygen Separation LACE:
[ LH2 Tank ]
|
v
[ LH2 Pump ] [Liquid Nitrogen]
| ^
| |
------------ v | __/
<Air Intake|->-[Heat ]-->---[liquid]-->--[Nitrogen ]-->--|_ Thrust ->
------------ [Exchanger] [air ] [Separator] ^\
| [pump ] |
| |
------ gaseous H2 -------------------------
Comments:
The poor mixture ratio of the Basic LACE is improved by making the
oxygen more concentrated by extracting Nitrogen.
LOX Spray LACE:
[ LH2 Tank ]
|
v
[ LH2 Tank ]
|
|
------------ v __/
<Air Intake|->-[ Heat Exchanger]-->---[liquid air pump]-->---|__ Thrust ->
------------ ^ | ^\
| | |
| ------ gaseous H2 ---------------------------
|
[LOX Pump]
^
|
[LOX Tank]
Comments:
To improve the poor mixture ratio of the Basic LACE, LOX is sprayed
into the sucked-in air. This increases the oxygen concentration,
and lowers the temperature of the air. Both contribute to increase
the liquification of the air. The LOX tank is small compared to
what is normally carried on a LOX/LH2 rocket.
Tank Return LACE:
[ LH2 Tank ]
| ^
v |
[ Main ] [ LH2 ] |
[ LH2 ]-<-[ Boost] |
[ Pump ] [ Pump ] |
| | |
| | _______^
------------ v v | __/
<Air Intake|->-[ Heat Exchanger]-->---[liquid air pump]-->---|__ Thrust ->
------------ ^ | ^\
| | |
| ------ gaseous H2 ---------------------------
|
[LOX Pump]
^
|
[LOX Tank]
Comments:
This scheme uses the heat sink capability of the LH2 storage to cool
down the gaseous H2 after circulating in the heat exchanger. They
also use this technique with the onboard LOX in some of their
designs, to have it help liquification as well.
Air Compressor LACE:
[ LH2 Tank ]
|
v
[ LH2 Pump ]
|
| ------------[Liquid Air Pump]-------
| | |
------------ v | v __/
<Air Intake|->-[Heat ]-->---[Air ]-->-[Heat ]-->--|_ Thrust ->
------------ [Exchanger] [Compressor] [Exchanger] ^\
| |
| |
------ gaseous H2 ----------------------------
Comments:
Increased air pressure from a air compressor, increases the
liquifying temperature of the air. Compressed air is sent to the next
heat exchanger, where it is liquified more easily. The air compressor
doesn't have to be so big because of the first stage heat exchanger
cryo-cooling the air. Liquid air is extracted from the first stage
heat exchanger output for efficiency of the air compression process.
Liquid Air Spray LACE:
[ LH2 Tank ]
|
v
[ LH2 Pump ]
|
| ---[Liquid Air Pump]-------
| | |
------------ v | v __/
<Air Intake|->-[Heat ]-->---[Air ]-->-[Mixer]-->--|_ Thrust ->
------------ [Exchanger] [Compressor] ^\
| |
| |
------ gaseous H2 ------------------------
Comments:
An optimization of the Air Compressor LACE. Spraying
liquid air can replace the last heat exchanger stage (weight savings).
Expansion Turbine LACE:
[ LH2 Tank ]
|
v
[ LH2 Pump ]
|
-----u-----------------------------
| | ^
------------ v v | __/
<Air Intake|->-[Heat ]-------- air -------->[Heat ]--->-|_ Thrust ->
------------ [Exchanger] [Exchanger] ^\
| | ^ |
| | | |
| |-------->[Expansion ]-------- |
| | [Turbine ] |
| | |
| ------------- gaseous H2 --------------------
|
| /
-----| H2 Exhaust
\
Comments:
After the first pass of the LH2 through the heat exchanger,
it becomes a gas. The gas is expanded through an expansion
turbine so that it can be chilled for re-use in another heat exchanger
stage.
General Comments:
The Japanese still have allot of work to do. Example, what about
humidity? Ie: Ice and CO2 (for that matter) buildup on the heat exchanger.
I mentioned heat exchanger weight already. Liquid Air pumps have to
be developed. A variable intake and exhaust nozzle for the very
wide performance range of this engine have to be designed.
The LACE concept originated in the USA in the late 50's. I think the Air
Force, back then, funded some research in this area. They found it to be
unfeasable, and dropped it, but materials science has sure improved
since then.
Personally, I'm glad the NASP consortium is exploring scramjets,
turbo-ramjets, and LACEs. But instead of developing one engine
technology only, why don't they develop several, and test fly them both.
They could have Pratt and Whitney develop scramjets and turbo-ramjets, and
let Rocketdyne develop the LACE principle, instead of having them both
do scramjet designs. After reading about LACEs I'm left with the feeling
that they might be easier to do than scramjets, because we're talking
about a Mach 5-10 air breathing engine (LACE), versus a Mach 25 air
breathing engine (scramjet). But don't get me wrong, scramjets and
turbo-ramjets are VERY important to develop ! At least we could use
LACEs on our vertical launched rockets as well.
Larry
| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 537.1 | HOPE spaceplane and the H-2 rocket | ADVAX::KLAES | All the Universe, or nothing! | Thu Sep 20 1990 12:47 | 99 |
| From: [email protected] (S H L G Bisson)
Newsgroups: sci.space
Subject: H-II and HOPE
Date: 19 Sep 90 10:36:42 GMT
Organization: Bath University Computing Services, UK
In a recent post I mentioned the model of the NASDA HOPE
spaceplane that I saw at SBAC 1990. I managed to pick up Mitsubishi
Heavy Industries publicity sheets on the H-II and HOPE projects, a
summary of which I am including as part of this posting. The H-II data
is much more detailed than that for HOPE, the HOPE sheet detailing
MHI's proposal to NASDA.
*******************************************************************************
H-II specifications:
Overall length : 49m
Diameter : 4m
Total weight : 264.0t
1st stage SRB 2nd stage
(LE-7) (LE-5A)
Propellant :LOX/LH2 Solid LOX/LH2
Prop. weight :86.2t 118.4t 16.7t
(2 units)
Ave. thrust :93t 320t 12.4t
(Sea level) (2 units) (Vacuum)
(Sea level)
Total burn time :320s 97s 610s
(Restartable)
Specific impulse:447.7s 273s 452s
(Vacuum) (Vacuum) (Vacuum)
Total Weight :98t 140.3t 19.6t
(2 units)
Fairing:
(Diam x Length) :4.1m x 12m
(Payload env.) :3.7m x 10m
Guidance :Strap-down inertial guidance system
Payload :2,200kg (into geostationary earth orbit)
The H-II will be Japan's main launcher for the 1990s, and will be able
to put 2 tonnes into geostationary orbit. It is a 2 stage rocket, with
2 SRBs for extra thrust.
The LE-7 engine is new, wheras the LE-5A was originally developed for the H-I.
Future objectives call for the use of the H-II as a launcher for the HOPE (H-II
Orbiting PlanE).
[Edited from the Mitsubishi Heavy Industries SBAC 1990 pamphlet "H-II Rocket"]
-------
H-II Orbiting Plane (HOPE):
Length :16.5m
Span (Total) :12.0m
Span (Wing) :10.0m
Height :5.0m
Payload :3,000kg
Dry weight :10,000kg
Landing weight :13,000kg
Hope is an unmanned winged space vehicle, to be launched from an H-II
rocket, augmented by six SRBs, in order to recover experimental
products from the space station and various platforms, and also to
supply logistics.
In addition experiments will be carried out from the cargo bay.
[Edited from the Mitsubishi Heavy Industries SBAC 1990 pamphlet "HOPE"]
********************************************************************************
Just to round things off, here's my tuppence worth to add to the ole
NASA debate A recent posting referred to the US lead in space
technology. Hmmm. A few lines resulted:
So as the US Space program stagnates, the European and Japanese
programs continue to grow, with new life for HOTOL, test bed engines
for Sa"nger, Hermes contracts and H-II and HOPE. I used to be very
much in favour of the NASA shuttle programme, but now it seems to be
time for a new generation of launchers. Whilst the rest of the world
reaches for the 21st century, the USA seems stuck in the 60s and 70s,
and the red tape will keep it there (tho' OSC is making an effort with
Pegasus.)
Just a comment from this side of the pond.
Simon Bisson...net.jerriais..."It was my Mum, she MADE me watch Apollo 11".....
|