Conference 7.286::space

    Note that the article referring to the Block 2 boosters did not
    say that Block 2 booster implementation was a prerequisite for future
    shuttle missions.  I assume that the Block 2 boosters are meant
    to replace the current booster design further down the road in the
    space shuttle's life (4-5 years if some NASA managers are correct).

     What does "Block 2" mean?

    Block 2 just means redesigned staying within the same basic guidelines,
    i.e. the block 2 boosters will be new designs but with the same
    external dimensions and probably the same performance (it could
    be improved a little).
    
    Similar examples from history include the Saturn 1 (block 1 birds
    only had the first stage active, block 2 had an improved 1st stage
    and an active 2nd stage) and the Apollo Command Module (the block
    1 CM was the one involved in the pad fire, block 2 was on the drawing
    board before the fire and was a much improved spacecraft).
    
    In VMSspeak, block 2 would be an update, not an upgrade :-)
    
    gary

    re .3:  Were the weight-reduced LEMs considered Block 2?  Or block
    n?
    
    Burns

re Note 240.4 by SKYLAB::FISHER:

>     re .3:  Were the weight-reduced LEMs considered Block 2?  Or block

I thought that they reduced the weight by removing the "E".  :-)

Bob

    Re new SRB's,what happened to the proposed filament wound boosters?

I thought the carbon-fillament SRBs had the
same field joints as the ordinary ones.
And I think they have actually stacked a pair
at Vandenberg.

Newsgroups: sci.space
Path: decwrl!decvax!ucbvax!AMES-PIONEER.ARPA!eugene
Subject: New thing on SRBs
Posted: 11 Mar 87 20:27:00 GMT
Organization: The ARPA Internet
 
--eugene miya
  NASA Ames Research Center
  [email protected]
  "You trust the `reply' command with all those different mailers out there?"
  "Send mail, avoid follow-ups, I'll summarize."
  {hplabs,hao,ihnp4,decwrl,allegra,tektronix,menlo70}!ames!aurora!eugene
 
Article 94 of nasa.telemail.lf:
Path: ames!telemail!hqnewsroom
From: hqnewsroom@telemail (ED CAMPION)
Newsgroups: nasa.telemail.lf
Subject: RELEASE/SRM MOTOR TEST
Message-ID: <HGIH-2516-8144@telemail>
Date: 11 Mar 87 15:10:00 GMT
Sender: [email protected]
Lines: 95
Approved: telemail
  
Sarah Keegan                                   March 11, 1987
Headquarters, Washington, D.C.
(Phone:  202/453-8536)
 
 
 RELEASE NO:  87-28
 
       SHUTTLE SOLID ROCKET MOTOR TEST FIRING UNDER REVIEW
 
    Detailed teardown analysis of the test article from the highly
successful solid rocket motor (SRM) joint environment simulator (JES)
firing at Morton Thiokol on Feb. 23, 1987, has indicated potential
insulation bonding deficiencies in the assembly process of the test
hardware.  NASA and Morton Thiokol are assessing options for
correcting this occurrence, which potentially affects the insulation
configuration in the area of the field joints on several other test
articles, including the first full-scale firing test, the Engineering
Test Motor (ETM-1). 
 
    Because the same fabrication/assembly process has been used on the
hardware for the ETM, the assessment and ensuing corrective actions
may cause a schedule delay for the test, which had been slated for
March 25.  It is not anticipated that this situation will cause a
delay in other motor test firings or the February 1988 target Shuttle
launch date. 
 
    The Engineering Test Motor is an interim step in the developmental
evolution of the redesigned SRM joints.  It does not have the
redesigned joint case hardware and will use motor segments
manufactured prior to the CHALLENGER accident but with modifications
in the joint insulation area to approximate the redesigned insulation.
A non-flight "U" seal is used in place of the "J" seal which has been
selected as the flight design.  The hand-fitting and secondary bonding
of this non-flight "U" seal led to the assembly concerns.  The
flight-design "J" seal will utilize precise, production-type molds
which create a homogeneous, one-piece insulation for each segment and
is not expected to be subject to the kind of problem encountered in
the ETM. 
 
    John Thomas, manager of the SRM Design Team at the NASA Marshall
Space Flight Center, stated today:  "We are fortunate to have
discovered this discrepancy in a short-duration Joint Environment
Simulator test firing rather than in a full-duration test.  The JES
program is accomplishing exactly what we designed it to do in terms of
providing early test demonstrations of planned or potential design
features.  Whatever the outcome of our Engineering Test Motor
deliberations, we retain full confidence in our baseline joint design,
which will be first demonstrated in the Joint Environment Simulator
#3A test, now targeted for June, and the full-scale Development Motor
#8 test, targeted for July.  Both of these motors contain not only the
improved "J" seal insulation system but the newly designed steel
capture feature field joint, as well." 
 
    This release and other NASA information is available
electronically through DIALCOM, INC.  For access to NASA NEWS through
this system, contact Jim Hawley, DIALCOM, INC. at 


    NASA has not yet decided whether to impose a $10M penalty on
Morton Thiokol's SRB contract as a result of 51L.  
[!!!!!!!!!!!!!!!!!!  -- HS] 
 
    "If the commercial development of space dies in the wake of the
CHALLENGER loss, it will not be the accident that killed it, but rather
the inability of NASA and other Government leaders to promptly
establish policy that will reassure investors in and supporters of
commercial applications that their activity has an important,
long-term place in the US space program." 
 
"We must choose: the stars or	  Henry Spencer @ U of Toronto Zoology
the dust.  Which shall it be?"	  {allegra,ihnp4,decvax,pyramid}!utzoo!henry

From: [email protected] (Matthew A Machlis)
Newsgroups: sci.space.shuttle
Subject: Shuttle Escape System
Date: 9 May 90 05:49:12 GMT
Sender: [email protected] (News system)
Organization: Massachusetts Institute of Technology
 
    I went to a VERY interesting talk today here at MIT by Dr. Jim
Bagian, who has a mechanical engineering degree and an MD and who was
a mission specialist on the first flight after 51-L (Challenger). 
During the flight hiatus after the Challenger accident, NASA put him
in charge of designing a crew escape system, as he had an engineering
background and the human factors experience necessary. 

    He said that the first design considered was ejection seats for
every member of the crew.  Unfortunately, NASA told him any system he
proposed had to be doable (conception through flight testing to
operational status) in 9 months, and fitting ejection seats for all
crew members (not just for the 2 up on the flight deck) would have
taken an absolute minimum of four years.  Another design considered
was some system to separate the entire crew module (which is already a
seperate structural section and very strong) and parachute it to
Earth, but this would have had a far, far too large weight penalty
(incidentally, he said that the biggest problem on the shuttle is CG,
not weight -- on some missions they have had to add 400 pounds of
ballast in the back of the cargo bay to offset the CG shift due to
adding one more crewmember in the cabin). 
 
    So they realized they needed some sort of escape system.  First
they considered a tractor rocket system, which has a set of small
solid- fuel rockets mounted in the wall of the crew compartment.  Each
astronaut would strap himself to one and then fire it, and it would
carry him clear of the orbiter where s/he could parachute to safety.
However, NASA basically forced the idea of a pole on Dr. Bagian even
though he did not think it practical.  They did a lot of design and
flight testing and did get it to work, and it is now a nice simple,
reliable system.  In an emergency, the cabin is depressurized, then
the hatch is blown, then each crew member in turn clips onto the pole
and jumps out the hatch.  The pole carries him far enough out into the
slipstream such that he will miss hitting the orbiter by at least 7
feet 99% of the time. 
 
    Now another major part of the escape system effort was that now
that there is the option of bailing out, the crew need suits which
will protect them from near-vacuum to free-fall to freezing-cold
water. The main (not the only) purpose for the escape system is if the
orbiter loses enough engines at such a time that it enters a glide but
cannot make an improved landing site.  It has been demonstrated that
there is virtually zero chance of anyone surviving a ditching or
landing on an unimproved landing site.  So the crew will have to bail
out, most likely over the Atlantic.  So new partial-pressure suits
were designed which contain enough oxygen for 9 minutes of breathing
at sea-level pressures (longer at altitude), can sustain consciousness
down to zero pressure (hard vacuum), which contain built-in exposure
suits to allow the astronauts to survive up to 24 hours in 40 degree
water (while waiting to be rescued), which contain built-in
automatically-deployed pilot/drogue/main parachute systems, and which
contain built-in life rafts.  All of this, and the suits -had- to be
designed so as not to impede the normal functioning of the astronauts
during the ascent.  They did an incredible job on the suits, and
astronauts have reported that there is very little reduction in
mobility between the new suits and the old flight suits, and even
better visibility through the helmet! 
 
    Now, where I disagree with something stated earlier: Dr. Bagian
stated that he believes that with this system, the Challenger crew
would have been able to successfully bail out. 

  #1: Challenger did not blow up -- the orbiter itself broke apart due to
 aerodynamic forces following the explosion

  #2: The crew compartment was completely intact all the way until it hit
 the water, and fell in a near-nose-down attitude with -very little or
 no tumbling-

  #3: To this day it is unknown whether or not the cabin depressurized
 before it hit the water.  However, with the new pressure suits it would
 not have mattered -- the crew would remain conscious in any case.  And
 the g-loads encountered during the fall of the crew compartment were
 not that great

  #4: It took over 2 1/2 minutes from the moment of the explosion until
 the crew compartment hit the water -- plenty of time for at least some
 of the crew to get out

    Dr. Bagian did say, however, that NASA does not like to play up
the fact that the crew of the Challenger could have been saved by this
system, for obvious reasons. 
 
    An interesting piece of trivia: according to Dr. Bagian, there was
a raging debate before the first shuttle flight over whether they
should purposely make it a launch and then return-to-launch-site
abort.  Robert Crippen's response to this idea was, "There's no need
to practice bleeding!" 

re .-1 (Challenger crew could have survived):  I wonder if there are separate
electronics and power supplies internal to the crew capsule which would blow
the door.  For that matter, I wonder how the door works.  It is not obvious from
pictures that it is a "two parter"...i.e. 1 through the skin and one in the crew
compartment.

re g-loads while falling:  Presumably after a short stabilization period, the
cabin should be under 1-g at its terminal velocity.  I wonder if the cabin is
designed such that the crew could get from their seats to the door under 1-g
if the capsule happened to be upside-down.  What if it were spinning or
tumbling?  Still lots of ifs, I suspect.

Burns

RE:     <<< Note 240.10 by 19458::FISHER "Prune Juice:  A Warrior's Drink!" >>>

>re g-loads while falling:  Presumably after a short stabilization period, the
>cabin should be under 1-g at its terminal velocity.... What if it were
>spinning or tumbling?

If the crew module was spinning, then a person could experience greater than
1G even once the crew module reaches terminal velocity and thus doesn't change
linear velocity.  If the spin rate were moderate to high (tens of RPM), and a
person was away from the center of mass by ten feet or so, I imagine the forces
could pin the person down pretty well.  This can be a problem in aircraft as
well; a number of lives have been lost because aircrew members could not bail
out or eject once an aircraft enters a fast spin (40-80 RPM) because they were
stuck -- either arms (preventing use of ejection devices) or whole body
(preventing bail-out).
						-- Tom

  I think I read that it fell nose down. At least that's the way it looked in
the pictures. At any rate, it doesn't seem that it would be that hard to modify
it so that it could be separated and fly/fall in a stable position. 

  George

From: [email protected] (Tarl Neustaedter)
Subject: Escape systems from shuttle
Date: 11 Jun 91 07:48:48 GMT
Organization: Stratus Computer, Inc.
 
In reply to Allan's comment about a properly equipped shuttle escape system
making shuttles safe; There is an article in this week's aviation week about
the russian escape system being installed in the second buran shuttle. It's
a modification of the one we saw so spectacularly deployed in the Mig-29
crash at an airshow a few months ago.
 
In any case, the escape system is limited to mach 4.1; Even at those speeds
they had to do some significant work to reduce wear and tear on the ejected
dummys, including worrying about burns when multi-mach air hits the dummy.
It will probably allow the astronauts to escape from a challenger-type
accident, but not much beyond it; In other words, you can solve the problem
for the very beginning and very end of the flight, for non-catastrophic
failures, but you still have a large amount of powered flight where you
can't escape.
 
The basic danger of solids, that you can't turn them off, can't be solved
short of using something else.