Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v12_5/v12_557.txt

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Subject: SPACE Digest V12 #557

SPACE Digest                                     Volume 12 : Issue 557

Today's Topics:
               Re: New Shuttle Engines
            The Ariane V36 failure
           Re: The great light bulb debate
             Re: LNLL Inflatable Stations
             Re: LLNL Astronaut Delivery
               Re: New Shuttle Engines
              Re: Name for LLNL station.
Re: The Ariane V36 failure (was Re: Ariane launches ON TIME! (again))

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Date: 13 Nov 90 19:05:28 GMT
From: snorkelwacker!usc!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Organization: U of Toronto Zoology
Subject: Re: New Shuttle Engines
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In article <[e-mail]> [e-mail] (Brett Vansteenwyk) writes:
>Not long ago it was noted that the first of Endeavour's engines had arrived
>at KSC.  Some mention was made that these engines were "new and improved".

Don't read too much into this.  There has been no major design change, just
a bunch of small incremental improvements.

>[1].Are these new engines useable in the older shuttles? ...

Yes.

>[2].Are these engines part of a more "mature" system?  In other words, has
>there been a batch of changes made to the manufacture/design of these "new"
>engines that will improve their servicability and ease of refurbishment?

That's the hope.  Considering the magnitude of the failure to meet the
original targets in these areas, there is room for a lot of improvement.

>This engine has been in use for almost 10 years, and it would seem
>that it could be classified as a "mature" system by now--a learning curve
>with subsequent reduction in refurbishment costs as well as a more reliable
>engine.  Is there evidence to indicate that this has happened? ...

Well, maybe some.  The thing you learn from the learning curve in this
case is really "these things will never be wonderful without major redesign".

>[4].Whenever I see any discussion about new launcher development, I never,
>or almost never see any suggestion to using the SSME's, nor do I see any
>indication of an engine derived from SSME technology.  The tendency is
>to discuss systems originating 25 or even 30 years back.  I am assuming
>that the SSME was the most recent major engine development.  Has all the
>time and talent spent to make the SSME work been wasted on what is now
>considered an evolutionary dead-end? ...

Very nearly.  The Japanese decided to adopt a similar approach (although
a from-scratch design) for their H-2 booster, and are now regretting it.
Most everyone else proposing new launchers wants to use less ambitious
and more dependable engines, either old ones or new developments.  The
SSME concept wasn't bad in principle, and maybe it is the wave of the
future if you're patient enough, but making it work well seems to be
exceedingly difficult today.  Certainly the SSME itself shows no signs
of ever becoming particularly cheap.

>[5].If not the evolutionary dead-end as postulated in [4], could there be
>an SSME derivative for an expendable launcher...

The definitive Shuttle C proposal wanted to use life-expired shuttle engines
in an expendable launcher.  The Hughes/Boeing Jarvis proposal also used
expendable SSMEs, after they tried very hard to come up with a viable
scheme for reviving the F-1 and J-2 and couldn't make it work.  The SSME
is just too expensive to be a good expendable engine, though.
--
"I don't *want* to be normal!"         | Henry Spencer at U of Toronto Zoology
"Not to worry."                        |  [e-mail]   utzoo!henry

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Date: 12 Nov 90 01:43:42 GMT
From: van-bc!rsoft!mindlink![e-mail]  (Bruce Dunn)
Organization: MIND LINK! - British Columbia, Canada
Subject: The Ariane V36 failure
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> [e-mail] writes:
>
> [commenting on a report that a piece of cloth in a water-line to an engine
> caused the Ariane V36 failure on February 22]
>
> I've never been part of a failure investigation (thankfully ;-)) since I
> joined NASA, so I don't know much about the procedure.  I hope someone can
> offer insight on the following questions:
>
> (1) the failure was due to a piece of cloth.  How could this have been
>     isolated after the failure?
> (2) what is the mechanism by which a piece of cloth was able to cause the
>     failure?  By that I mean
>     - was the cloth of sufficient size/porosity to totally restrict water
>       flow?  or did it have to be?
>     - how is a piece of cloth able to be in the water line anyway?
>     - what is the sequence of events leading to the failure, given the
>       presence of the cloth?
> (3) how can Arianespace ensure no repeat of this mechanism/sequence of
>     events?
>


     The following information, abbreviated from 3 issues of Spaceflight, may
be of interest.

May, 1990:
     The Ariane V36 Inquiry Board has presented its findings.  They identify a
blocked water line as the cause of the accident.  The launcher exploded shortly
after its launch on February 22. ...  The loss of the mission was due to the
decrease in thrust of one of the four Viking V motors on the first stage.  The
drop in thrust occurred 6.2 seconds after motor ignition.  It was due to an
almost total obstruction of the water feeding circuit of Viking motor D.  The
engine itself is not at fault.  The obstruction occurred upstream of the motor
before the water pump.  The precise cause of the obstruction is either a
foreign object in the pipe or a failure of the main water valve.      [The
article goes on to talk about how debris from the exploded launcher fell at the
shoreline and just off-shore of the launch site.]       A search of mangrove
swamps in zone 2 located some 350 different objects from the first, second and
third stages.  In particular, this search located external tubing of engine D
as well as water tank elements.  The first stage propulsion bay along with the
four Viking motors was found.  Despite extremely difficult conditions, the
suspect elements of the water circuit were recoverd shortly before this issue
of Spaceflight went to press.

June, 1990:
     The loss of Ariane V36 was caused by a small piece of cloth that blocked
the water supply to one of the vehicle's first stage engines.  ...  The rag was
probably left in the pipe when the tubing was dismantled and readjusted during
first stage integration before transfer to French Guiana.  Arianespace Chairman
Frederic c'Allest said the cause of the failure was "not only shocking but hard
to accept."

September, 1990:
     The investigation into the loss of V36 revealed that a first stage engine
lost thrust because a small piece of cloth blocked a water pipe.  In an
unconnected incident a small fire broke out in one of the strap-on liquid
boosters due to a fuel leak. From flight V37, the water line and the N2O4 feed
line of each engine will be examined.  The inspection will take place at
Kourou, using a fibroscope type video camera with integrated light source. ...
Additional leak checks were made on the first stage and strap-on fuel lines to
ensure that there was no repeat of the fire on the previous mission.  Also, new
thermal protection inside the propulsion bays of the first stage will protect
electrical systems in the event of a fire.

Spaceflight is an excellent journal received by members of the British
Interplanetary Society. Address: 27/29 South Lambeth Road, London, SW8 1SZ,
England.

     My understanding is that as the engine lost thrust, the remaining engines
gimbeled to correct for the thrust imbalance.  When the running engines reached
the end of their gimbel limits the vehicle could no longer be kept on course,
and in effect started to skid sideways through the air.  Breakup due to
aerodynamic forces followed shortly.  What I have not been able to find out is
why Viking engines need a water supply.  This is presumably for cooling,
however I have never heard of an engine that used anything other than its own
propellants as a cooling source.  Can someone familiar with the Viking engine
explain the function of the water, and what happens when its supply is
interrupted.
--
Bruce Dunn   Vancouver, Canada    [e-mail]

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Date: 13 Nov 90 17:26:42 GMT
From: att!cbnewsl!moss![e-mail]  (Forrest Gehrke,2C-119,7239,ATTBL)
Organization: AT&T Bell Laboratories
Subject: Re: The great light bulb debate
References: <[e-mail]>, <[e-mail]>
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In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (John Roberts) writes:
>>The "inert" gas usually cited in the literature is nitrogen. Why would
>>krypton be better than argon?
>
>Nitrogen is not really inert when temperatures get high.  For example,
>if you burn titanium in air -- 80% nitrogen, 20% oxygen, roughly -- the
>ash is about 80% titanium nitride and 20% titanium oxide.  For applications
>involving incandescent metals, you want something that is really inert.
>(If you're being really picky, the noble gases [the preferred modern term]
>are not really inert either, but under these conditions they qualify.)
>
>Krypton is better than argon for the same reason that argon is better than
>vacuum:  the denser gas slows the evaporation of the tungsten filament.


And because of the slower evaporation there is another advantage:
The tungsten filament can be operated at a higher temperature; these
bulbs are significantly brighter.

Halogens (usually pure iodine) are still better (although a different
process is taking place).  But now, due to the high temperatures being
reached, quartz glass must be used for the envelop.  This is expensive
and their applications become more specialized, such as automobile
headlights, photography, etc.

Forrest Gehrke [e-mail]

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Date: Tue, 13 Nov 90 16:42:45 -0500
From: "Allen W. Sherzer" <[e-mail]>
To: [e-mail]
Subject: Re: LNLL Inflatable Stations
Newsgroups: sci.space
In-Reply-To: <[e-mail]>
References: <[e-mail]> <[e-mail]>
Organization: Evil Geniuses for a Better Tomorrow
Cc:

In article <[e-mail]>:
>> [LLNL Earth Station will require fewer crew changes because
>>  they provide artificial G]

>Soviet crews have stayed in orbit for over a year. They have demonstrated
>that with advanced exercise machinery and lots of exercise it is possbile
>to return to the Earth after a year in a 0g environment and completely
>recover.

True but they don't do it as a matter of routine. In a staion with
artificial gravity crew endurance is not limited by microgravity.

All things being equal a crew in the LLNL Earth Station will not need
to be rotated as often as Freedom. Since it will cost several hundred
million $$ to do a rotation, this is a major consideration.

  Allen
--
+---------------------------------------------------------------------------+
|Allen W. Sherzer| I had a guaranteed military sale with ED-209. Renovation |
|   [e-mail]  | programs, spare parts for 25 years. Who cares if it      |
|                | works or not?  - Dick Jones, VP OCP Security Concepts    |

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Date: 12 Nov 90 18:05:04 GMT
From: sdd.hp.com!samsung!umich!umeecs!msi.umn.edu!cs.umn.edu!sialis!orbit!pnet51![e-mail]  (S Schaper)
Organization: People-Net [pnet51], Minneapolis, MN.
Subject: Re: LLNL Astronaut Delivery
Sender: [e-mail]
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Why not let the free-flyer be the one to orbit without the thruster
corrections, except for the ones necessary to maintain orbit, let the manned
platform do the formation flying? That may turn out necessary for Freedom as
ell
to have the materials sciences on a separate platform - an expanded Columbus,
and let the manned platform do the biological experiments and have the SEI
and OMV's to service the Columbus and EOS platforms.  Perhaps an LLNL spun
section could be added to the station. Even sent up first to house astronauts
for construction phase? Thoughts, as this is also problematic.


Could Hermes be launched from an upgraded Titan IV (LRB's)? We could purchase
some for crew transfer, freeing the aging shuttle fleet for what it does best.

Zeitgeist Busters!

UUCP: {amdahl!bungia, uunet!rosevax, chinet, killer}!orbit!pnet51!schaper
ARPA: crash!orbit!pnet51![e-mail]
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Date: 13 Nov 90 22:33:43 GMT
From: sdd.hp.com!wuarchive!rex!rouge![e-mail]  (Fraering Philip)
Organization: Univ. of Southwestern LA, Lafayette
Subject: Re: New Shuttle Engines
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In article <[e-mail]> [e-mail] (Henry Spencer) writes:

HS>in an expendable launcher.  The Hughes/Boeing Jarvis proposal also used
HS>expendable SSMEs, after they tried very hard to come up with a viable
HS>scheme for reviving the F-1 and J-2 and couldn't make it work.  The SSME
HS>is just too expensive to be a good expendable engine, though.

?

I was under the impression that the reason Jarvis was not built,
in either 'incarnation,' was because of political reasons. After all,
isn't the shuttle the most capable vehicle ever built?

Phil

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Date: 12 Nov 90 18:45:02 GMT
From: sdd.hp.com!samsung!umich!umeecs!msi.umn.edu!cs.umn.edu!sialis!orbit!pnet51![e-mail]  (S Schaper)
Organization: People-Net [pnet51], Minneapolis, MN.
Subject: Re: Name for LLNL station.
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I. Freedom 2
II. Von Braun Station
III. Base Camp Freedom II
IV. Oz

Zeitgeist Busters!

UUCP: {amdahl!bungia, uunet!rosevax, chinet, killer}!orbit!pnet51!schaper
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Date: 13 Nov 90 18:54:58 GMT
From: swrinde!zaphod.mps.ohio-state.edu!samsung!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Organization: U of Toronto Zoology
Subject: Re: The Ariane V36 failure (was Re: Ariane launches ON TIME! (again))
References: <[e-mail]>, <[e-mail]>, <[e-mail]>
Sender: [e-mail]
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In article <[e-mail]> [e-mail] writes:
>(1) the failure was due to a piece of cloth.  How could this have been
>    isolated after the failure?

They pinned down possible causes based on the symptoms, and then went through
the recovered debris very carefully, and found the cloth.

>(2) what is the mechanism by which a piece of cloth was able to cause the
>    failure?  By that I mean
>    - was the cloth of sufficient size/porosity to totally restrict water
>      flow?  or did it have to be?

I believe it was large enough and solid enough to completely block the line.
We're not talking about 30-cm pipes here.

>    - how is a piece of cloth able to be in the water line anyway?

Good question.  Nobody knows for sure.  The obvious possibility is some
minor blunder during manufacturing.  If that's the case, there is little
hope that the person responsible will ever admit it.

>    - what is the sequence of events leading to the failure, given the
>      presence of the cloth?

Water flow to one engine chokes off, chamber pressure and thrust in that
engine drop, the other engines gimbal farther and farther to compensate,
eventually they hit their gimbal limits and the booster starts to turn,
and the attempt to fly sideways exceeds its structural limits and it
breaks up.

>(3) how can Arianespace ensure no repeat of this mechanism/sequence of
>    events?

The usual:  more care during manufacturing, more thorough inspections,
and some managerial changes to clarify who's responsible for that water
line (one company had hold of each end and nobody was in charge of the
whole thing).
--
"I don't *want* to be normal!"         | Henry Spencer at U of Toronto Zoology
"Not to worry."                        |  [e-mail]   utzoo!henry

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End of SPACE Digest V12 #557
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