Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_5/V15NO535.TXT

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Date: Sat, 12 Dec 92 05:10:14
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #535
To: Space Digest Readers
Precedence: bulk


Space Digest                Sat, 12 Dec 92       Volume 15 : Issue 535

Today's Topics:
                          "success oriented"
              absolutely, positively overnight (2 msgs)
                            Air Force One
                                Aurora
              Cassini Undergoes Intensive Design Review
                             Earth Movie
                               Jet Lag
                             liquid fuels
                       Mach 8+ Space/Spy Plane?
                           Orbit Question?
                          Presidential DC-1?
  Profit in space activities (was: absolutely, positively overnight)
                            Saturn history
                   Scud Missile technology (2 msgs)
                         Shuttle replacement
                        Shuttle thermal tiles
           Terminal Velocity of DCX? (was Re: Shuttle ...)
          WFPC-2 Will Magnify Hubble's Views of the Universe
                   what the little bird told Henry

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----------------------------------------------------------------------

Date: Fri, 11 Dec 92 21:25:52 EST
From: John Roberts <[e-mail]>
Subject: "success oriented"

-From: [e-mail] (Edward V. Wright)
-Subject: Re: what the little bird told Henry
-Date: 11 Dec 92 17:56:29 GMT
-Organization: Engineering, CONVEX Computer Corp., Richardson, Tx., USA

-I'd be curious to know the exact date, sometime in the last 20 years,
-when "success oriented" became a pejorative phrase.  Yeah, the project
-is success oriented.  Just like Project Apollo.  The alternative, I
-guess, is for a project to be "failure oriented."  I like success better.

In that context, I'd say that "success oriented" means that everything in
the design process has to work right the first time, or the project is
judged a failure. (In other words, the design process *assumes* success
at every stage - there are no provisions for setbacks.) Perhaps another
term would be better - like "recklessly self-assured".

I don't think you could call Apollo success oriented - there were numerous
backup design paths, redundant test spacecraft (for instance, five Lunar
Orbiters were made and used, though three were sufficient to map the
Apollo landing sites), and the program progressed in many incremental
stages, testing various aspects of the mission in turn. It was considered
a very high priority to have a successful mission within a specific time
frame, and they approached the problem by throwing vast quantities of
money at it.

The DC program is more success oriented than Apollo, but that's part
of the idea of the design approach (as you point out) - taking higher
risks in the design process with the potential payoff of lower design
costs, and *perhaps* shorter design time.

But even DC is testing things in stages - two generations of prototype
craft, and a careful testing sequence for each prototype. So perhaps
"success oriented" is not the best way to describe the program.

John Roberts
[e-mail]

------------------------------

Date: Fri, 11 Dec 1992 01:50:59 GMT
From: Mary Shafer <[e-mail]>
Subject: absolutely, positively overnight
Newsgroups: sci.space

On 11 Dec 1992 00:45:47 GMT, [e-mail] (Anthony J Stieber) said:

A> Are the speeds SR-71 craft fly at
A> considered hypersonic?

No, they're not.  Essentially, it's not hypersonic below about Mach 5.
The definition floats around depending on who you're talking to, but
Mach 5 is a number that's pretty much agreed on.  At Mach 3, the heating
is starting to become interesting, but it's not really interacting with
the aerodynamics.  At Mach 5, the heating is interacting with the
aerodynamics.
--
Mary Shafer  DoD #0362 KotFR NASA Dryden Flight Research Facility, Edwards, CA
[e-mail]                    Of course I don't speak for NASA
 "A MiG at your six is better than no MiG at all."  Unknown US fighter pilot

------------------------------

Date: Thu, 10 Dec 1992 23:46:25 GMT
From: Josh 'K' Hopkins <[e-mail]>
Subject: absolutely, positively overnight
Newsgroups: sci.space

[e-mail] (Henry Spencer) writes:

I had written...
>>I'm no expert on jet lag.  It just seems like going from breakfast to a late
>>dinner in the time it takes to skim a good magazine would have to throw your
>>system off.  Since jet lag is way off the subject...

>Actually, not entirely off the subject.

>The problem in jet lag is the timezone change from origin to destination.
>How long it takes to get there is, to a first approximation, irrelevant.
>Although the airlines often make some attempt to smooth the transition,
>you can think of the situation as staying on origin time until you step
>off the plane, at which point you suddenly have to shift to destination
>time.
>However, on closer examination, trip time is relevant... because a long
>fatiguing trip can only make the problem worse.  The shorter the better.

In my experience being on a plane is no problem - it's those darn terminals that
make it a pain.  I remember flying Paris-Cleveland and spending the majority of
the time on the ground.  Trust me, JFK at 2 AM isn't fun.  Intercontinental
travel via suborbital vehicle will be just as much of a pain unless we also
solve scheduling, passenger processing and ground transport problems.

On the subject of jet-lag, I think you may have made a few incorrect
assumptions.  I use time on the plane to at least start to adapt, or at least
I think I do. I can go to sleep a little early or a little later.  If I fly
aboard TranSpace airlines I won't have time to sleep - I'll just have to deal
with it when I get there.

>(I assume we're talking about surface-to-surface travel, not surface-to-space,
>which is a very different market with a proven audience.)

That was the subject in mind.  I agree on space tourism.  Do you have any
numbers to post though?

--
Josh Hopkins                                          [e-mail]
                        Ho^3     !=L

------------------------------

Date: Fri, 11 Dec 92 20:54:03 EST
From: John Roberts <[e-mail]>
Subject: Air Force One

-From: [e-mail] (Gary Coffman)
-Subject: Re: absolutely, positively overnight
-Date: 11 Dec 92 17:24:37 GMT
-Organization: Gannett Technologies Group

->I'm sure that if certification were suitable and appropriate facilities
->were widespread, there'd be a few executive DC-1s bought.  The Saudi
->royal family would surely buy one.  And then there's Air Force One...

-Take a look at Air Force One, or Two. A 747 and a 707.

I was under the impression that there are two 747s. There was a television
special on the history of Air Force One several months ago, but I don't
think I saved the tape.

(One amusing anecdote from the show - when Kissinger was Secretary of State,
he had quite a reputation as a "ladies' man". He would be seen at a party on
Friday night with one of various women, then disappear, and show up again
on Monday, looking exhausted. In fact, he would drop off the woman after
leaving the party, go to Andrews, and take Air Force One to Europe for
secret talks with the North Vietnamese. I suppose he became an expert on
the subject of jet lag. :-)

-The Air Force
-is very conservative in the choice of aircraft on which to fly the
-President. The Saudi royals are even more conservative. Maybe a
-playboy nephew might be allowed on a high performance aircraft,
-but none of those directly in line for the throne.

In contrast, King Hussein of Jordan has been known to fly *himself*
to DC for a conference with the President.

John Roberts
[e-mail]

------------------------------

Date: Thu, 10 Dec 1992 23:31:26 GMT
From: Brad Whitehurst <[e-mail]>
Subject: Aurora
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>Bob Waterman writes (8 Dec 92 22:19:48 EST):
>
>>Thought Y'all might find this interesting (those financial guys
>>
>>From Wall Street Journal...
>>
>>Magazine Suggests Aircraft Has Flown Mach 8 for Years
>> ... (too long, suppressed) ...
>
>Very interesting indeed. Thanks for posting that article.
>Now a few comments about this mysterious triangular aircraft:
>
>1). In the article "Recent Sightings of XB-70-like Aircraft Reinforce
>1990 Reports from Edwards Area", AW&ST (August 24, 1992) reports a few
>sightings of what they assume to be a TSTO (Two Stages To Orbit) object.
>The first sightings (1990-1991) were of a "primarily delta-shaped"
>aircraft. Only in the two last sightings (1992) were reported a "narrow
>fuselage" and/or a "forward wing or canard". Maybe these two last
>sightings can be discarded (IMHO, all these sightings are no more
>convincing than UFO sightings: just apply the CSICOP criteria to
>these AW&ST articles...). If they can be discarded, then we are left
>with reports of "triangular" aircrafts in the Wall Street Journal and
>in the AW&ST article. My conclusion: maybe Aurora and the "XB-70-like"
>aircraft are the same beast, in which case there is no TSTO, only a
>hypersonic spy plane.
>
>2). Unknown triangular crafts have been reported over Belgium in 1989-
>1990-1991, and there have been more than a few sightings: something
>like one thousand! On the only good photo which exists of this object,
>it has a 82-degrees nose, not far from the 75-degrees reported in the
>Wall Street Journal (I know, it depends on perspective). However, these
>crafts could hover silently. Could Aurora go at Mach 8 and also hover
>silently? Seems very unlikely. So the Belgian objects were probably
>not Aurora, maybe just a hoax... but:
>
>3). In its December 1991 issue, Popular Mechanics (article "America's
>New Secret Aircraft") reports, near Edwards AFB, a big triangular object
>which, like the Belgian object, can hover silently horizontally and
>vertically... Hence the hypotheses:
>
>a) The USA have really a extraordinary triangular plane, which can
>both hover and reach Mach 8.
>
>b) The USA have a triangular spy plane which goes at Mach 8, and a
>triangular airship which looks like this plane. Maybe the airship
>has been built just in order to confuse people.

>
>c) Popular Mechanics and AW&ST are no more serious than UFO reviews.
>
>J. Pharabod

    I'll believe AW&ST over the Wall Street Journal and Pop
Mechanics any day!  They've got an intelligence net second only to the
CIA...hmmm, mebbe even better!
--

Brad Whitehurst    |   Aerospace Research Lab
[e-mail] |   We like it hot...and fast.

------------------------------

Date: Thu, 10 Dec 1992 23:25:27 GMT
From: Hayim Hendeles <[e-mail]>
Subject: Cassini Undergoes Intensive Design Review
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
> ...
>     After flybys of Venus (twice), Earth and Jupiter as it loops
>around the sun to pick up energy, Cassini will arrive at Saturn
>in November 2004, beginning a four-year orbital tour of the
>ringed planet and its 18 moons. The Huygens probe will descend to
>the surface of Titan in June 2005.

Pardon my asking an ignorant question, but I can't understand why it
should take 7 years to get to Saturn. When Voyager went to Jupiter and
Saturn, it took (if I recall correctly) 4 years and a Jupiter flyby to
make it to Saturn. Here, you are using 4 flybys, and it's taking you 7
years! I would think that if you were to adjust the launch date so that
Jupiter and Saturn were in the same relative positions as they were in
1977 (when Voyager was launched), you could do the same trick again (in
the same 4 years).

Thanks for your help.

HAyim Hendeles

------------------------------

Date: 11 Dec 92 00:04:32 GMT
From: Miroslaw Kuc <[e-mail]>
Subject: Earth Movie
Newsgroups: alt.sci.planetary,sci.space

In article <[e-mail]> [e-mail] (David Toland) writes:
>In article <[e-mail]>, [e-mail]
> (Thomas E. Smith [LORAL]) writes...
>>I have another question that maybe Ron Baalke can answer. Is Galileo going to
>>take any footage of the lunar eclipse tomorrow? I think that would be an awesome
>>short movie, and a once in a lifetime chance.
>
>Too bad it's not a solar eclipse.  Footage of the moon's shadow crossing
>the earth's surface would really be striking!
>
It is true, however, we get this from weather satelites!
Miro

--
[e-mail]
[e-mail]

------------------------------

Date: Fri, 11 Dec 92 17:14:21 EST
From: [e-mail]
Subject: Jet Lag

>>The big problem with
>>transoceanic flight is that it would be much to expensive (and besides the
>>jet lag would be awful :-).

>I believe you have that backwards.  My understanding is, the faster the
>flight, the less the jet lag.

Think about it.  If you take a tramp steamer, the difference between your
local time and POD time is very small, per unit of travel time, so you
can catch up on the difference as you go.  The faster you travel, the
bigger is that difference, and the less time, during travel, you have to
keep in-phase.

That's why they call it 'jet-lag' instead of 'boat-lag' or 'horse-lag'.
(Imagine the problems with tranporter-lag :-)

-Tommy Mac
-----------------------------============================================
Tom McWilliams              | What a tangled web we weave, when at   ". |
[e-mail]      |              ,  .first we .practice .*'  .|
[phone] -or- 353-2986|            '. '  . . to decieve    ,      |
a scrub Astronomy undergrad | After that, the  ,          +             |
at Michigan State University| improvement is tremendous! '.  , .'       |
------------------------------===========================================

------------------------------

Date: Fri, 11 Dec 92 20:37:21 EST
From: John Roberts <[e-mail]>
Subject: liquid fuels

-From: [e-mail] (Frank Crary)
-Subject: Re: Cassini Undergoes Intensive Design Review
-Date: 11 Dec 92 18:28:29 GMT
-Organization: University of Colorado, Boulder

-After the Challenger failure, NASA added a safety requirement that
-nothing launched in by a space shuttle may use liquid fuels. That
-means Cassini must use lower-energy solid rockets instead.

I think you mean *cryogenic* fuels. Magellan, Galileo, and Ulysses all
use liquid fuels.

As I mentioned earlier, some of the post-Challenger Shuttle safety rules
are being relaxed (following intensive review, of course). Perhaps this
rule will eventually be one of them. Henry has indicated he would favor
such a change.

John Roberts
[e-mail]

------------------------------

Date: Fri, 11 Dec 1992 00:27:26 GMT
From: "Rich (the Wiz" <[e-mail]>
Subject: Mach 8+ Space/Spy Plane?
Newsgroups: lcc.junk,sci.aeronautics,sci.space

    My wife heard a snippet of an interesting news story late
    last week...

    Apparently reported in some English Aeronautic Journal was
    a story claiming that the US has a new spy plane capable of
    Mach 8+ (at least) in test.  Apparently said plane has a
    glide path over Catalina while landing in Nevada.  The story
    claimed that this plane was responsible for the periodic
    "mysterious sonic booms and window shaking" (Thursday mornings?)
    that have been occuring here in Southern CA.

    Anyone know anything more?


--
Rich Silva
Locus Computing Corporation           [e-mail]
          {uunet,ucivax,trwrb}!lcc!rich
       {randvax,ucbvax,trwspp}!ucla-se!lcc!rich

------------------------------

Date: 11 Dec 92 01:45:31 GMT
From: Pat <[e-mail]>
Subject: Orbit Question?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Josh 'K' Hopkins) writes:
>[e-mail] writes:
>
>[On the subject of statites (stationary satellites)]
>
>>Okay I understand what you are saying about the geo sync orbit, but what if the
>>body you wanted to remain over one of the poles was able to produce its own
>>electricity (i.e. very large solar array) which would be used to power ion
>>thrusters to keep it in place?
>
>Ion thrusters still require fuel their just much more efficient than chemical
>rockets.  The only system that can stay stationary over long terms is a solar
>sail.  Nature may permit some neat tricks with magnetodynamic tethers but I
>can't think of any that would work in this situation.
>

How about this.
At the North pole,  the lines of force are headed almost straight down
and beaucoup  charged particles are spiraling down.

Could you set up a large circular superconducting lariat and gain impulse
against either the  magnetic field or the charged particles???

sorta like zubrins idea for a mag sail????

------------------------------

Date: Fri, 11 Dec 92 21:00:05 EST
From: John Roberts <[e-mail]>
Subject: Presidential DC-1?

-From: [e-mail] (Pat)
-Subject: Re: absolutely, positively overnight
-Date: 11 Dec 92 19:01:00 GMT
-Organization: UDSI

-If the President used one,  then you'd have to buy at least 4-5.
-first there is the dual backup, so no terrorist knows which one he is in.
-then the secret service would want one or two to fly escorrt, rigged out
-with weapons, in case of alien hijackers.  plus the press would need one.

That seems to be the standard method for helicopter flights to Camp David
(at least based on personal observation), but not for the 747(s) - the
mode of flight is different.

John Roberts
[e-mail]

------------------------------

Date: Thu, 10 Dec 1992 19:07:09 GMT
From: "Mitchell E. Gold" <[e-mail]>
Subject: Profit in space activities (was: absolutely, positively overnight)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Josh 'K' Hopkins) writes:
>                          On the subject of expense, the Concorde seems a
>good example.  It's never been profitable enough to make anyone else want to
>buy one and it's at least 1.5 orders of magnitude cheaper than I can see a DC
>type vehicle being.  So where's the motivation for passenger travel?

The last I'd heard, the companies flying Concordes (British Air, anyone else?)
had decided to write off the amount of money that was used in development of
the aircraft, but the aircraft do make a good profit over operational costs.
--
Mitchell Gold, [e-mail]

------------------------------

Date: 11 Dec 92 01:34:00 GMT
From: [e-mail]
Subject: Saturn history
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Henry Spencer) writes...
>In article <[e-mail]> [e-mail] (Pat) writes:
>>>The first Saturn I flew on 27 Oct 1961, actually.
>>
>>So if the Saturn I  was ready in 61,  why didn't they use it for
>>Gemini?
>
>The test flights needed to make it ready (by von Braun's standards) covered
>the next several years.  For one thing, the first few flights had no upper
>stage and were incapable of making orbit.
>--

This is very true and also what Von Braun wanted to do with the Saturn V. They
wanted to fly the Saturn first stage, the two stages, etc.... The success of
the Saturn IB flying the SIVB Saturn stage allowed them to do what they
called "full up" testing, where the launched the full stack on  the first
SV flight.

By the way the Saturn I had a perfect record, 28 launches and no failures.
Also a thing of note is that the Centaur was originally designed and flown
on the Saturn I as the upper stage.

Dennis, University of Alabama in Huntsville.

------------------------------

Date: Thu, 10 Dec 1992 15:23:52 GMT
From: Ben Burch <[e-mail]>
Subject: Scud Missile technology
Newsgroups: sci.space

In article <[e-mail]> Lawrence Curcio,
[e-mail] writes:
>Anyway, the most amusing part was that he claimed the missile was
>programmed through the medium of *paper tape*. It's amazing they got any
>of those things off the ground :)

Now, just a minute!  It is really easy, sitting here in front of our
megapixel GUI workstations to think that electromechanical computing
is a failed technology, but in reality it was a quite robust and well
implemented technology.  It was neither as small, fast, or reliable as
modern microelectronics, but it worked, and worked well enough for many
applications, missiles being one of those.  If one designs one's control
laws around the basic speed of the machine, a missle generally does
nothing that requires intense computation or rapid response.  One
assumes that the trajectory is pre-planned, and that anything on the
missile requiring rapid feedback is handled by analog computers.

( Yes, I saw the smiley, but I couldn't resist. )

-Ben Burch

------------------------------

Date: Fri, 11 Dec 1992 06:00:57 GMT
From: Frank Crary <[e-mail]>
Subject: Scud Missile technology
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Dennis Newkirk) writes:
>Scud B Specs: 11.5 m by 84-90 cm., weight 6370 kg., storable liquid
>propellants, inertial guidance, range 280-300 km, nuclear-chemical-
>HE warheads at 770-860 kg...

The Sucd missiles used by Iraq against Saudi Arabia and Israel had been
modified, sacrificing payload and structural integrety for range. I think
the ranges of these modified missiles went up to ~500 km, and the
payload was well under 500kg. They also had a demonstrated habit of
braking up in mid-air... Aviation Week had a number of articles on
the subject, during and just after the war. I believe there was
also a multi-stage version (e.g. a cluster of scuds acting as
a first stage and a single scud as the second stage) which was
tested once, a few months before the invasion of Kuwait, but never
used otherwise.

                                                    Frank Crary
                                                    CU Boulder

------------------------------

Date: Fri, 11 Dec 1992 00:46:09 GMT
From: Rich Kolker <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space.shuttle,sci.space

In article <[e-mail]> [e-mail] (Peter Jarvis) writes:
>In article <[e-mail]> [e-mail] (Rich Kolker) writes:
>>
>>..... The Saturn V at MSFC is the Engineering
>>test model, not a flight article.
>Rich, I assume you mean the one at the Space and Rocket Center. There
>isn't one at MSFC. :-)
>
>Peter..........
You got me.  Of course SRC is built on land donated by MSFC, which is on land
that was part of the Redstone Arsenal....

By the way, the Saturn V at JSC is the last item brought to JSC on thre
barge canal before they filled it in.  By the way, my LATEST information
(from Space News Roundup, the JSC newspaper) is that it was Apollo 18's
bird.  Now I don't know who to believe.

>>-------------------------------------------------------------------
>>   rich kolker       [e-mail]
>>                          It's been a long, long time
>>--------------------------------------------------------------------
>

------------------------------

Date: Fri, 11 Dec 92 20:24:21 EST
From: John Roberts <[e-mail]>
Subject: Shuttle thermal tiles

-From: [e-mail] (Loren Carpenter)
-Subject: Re: what the little bird told Henry
-Date: 11 Dec 92 18:36:00 GMT
-Organization: Pixar - Pt. Richmond, CA USA

->>BUT: if the main place where NASP materials seem to be being used is
->>the heat shielding, and its re-entry temperature is lower than the
->>shuttle's, wouldn't shuttle re-entry materials be just as useful?

-    Indeed.  I have an engineering sample of the white tile material.
-    It has a color, density, hardness and stiffness similar to a fine
-    grained foamed chalk.  At first it seems like a smooth styrofoam,
-    firm and warm, but little white dust particles flake off as you
-    handle it.  It would be easy to stick a pencil clear through a tile,
-    though it would probably crack.  A moderate hailstorm would require
-    replacing all of them.

I don't think it's quite as bad as it sounds - the outer surface has a
hard coating. Also, I understand much of the Shuttle surface (presumably the
upper surface) is now covered with some sort of "thermal blanket" rather
than the tiles.

Inspecting tiles on the DC-1 would probably be a nuisance in terms of its
expected low maintenance requirements, but it seems to be only a small
fraction of the maintenance effort required by the Shuttle - I think they
normally just run a visual check, which might take a day or two. From
listening to post-flight briefings, I gather that losing two or three tiles
to runway debris might be considered typical.

The Shuttle launch towers have movable covers which protect the orbiter
from damage by hail and severe storms.

It's interesting to recall the extreme concern over the thermal tiles
before STS-1. Many people were convinced that the tiles would all fall
off during reentry. (The fact that Enterprise lost many of its tiles during
transport, and that Columbia lost some off its engine covers during launch
added to the concern.) Now it seems to be treated as a solved problem (except
for the weight, of course, and the inability to fly the Shuttle through
rain during landing). I got to play with some Shuttle tile replicas
at the Technology 2002 conference - they're being promoted as a solution
to some Earth-based problems.

Speaking of thermal protection - I saw some video taken on the flight
deck during reentry - if you look out the front windows on the way down,
you see a bright orange glow.

John Roberts
[e-mail]

------------------------------

Date: 11 Dec 92 04:53:14 GMT
From: Philip Young <[e-mail]>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

(Edward V. Wright) writes:

|> If that's true, a supertanker must also push the edge of the envelope.
|> But, of source, that's absurd.

Tell that to the Spaniards 8^}

--
Philip R. Young                   | Sir Lloyne might rib his friends,
Data General Australia Pty. Ltd.  | but he always gets in for his chop.


------------------------------

Date: Fri, 11 Dec 1992 00:41:12 GMT
From: Phil Fischer <[e-mail]>
Subject: WFPC-2 Will Magnify Hubble's Views of the Universe
Newsgroups: sci.space,sci.astro

In article <[e-mail]>
[e-mail] writes:


>     With its corrective optics, scientists expect the telescope
>will be able to provide the highest sensitivity to detect objects
>10 times fainter than those visible from Earth-based telescopes,
>with about 10 times greater spatial resolution.
>                                      ###


I don't want to offend anyone, but this is simply not true. It might have
been true if the HST was launched in the early 80s as originally planned.
Ground-based telescopes (CFHT) can routinely acheive resolution (seeing) of
0.4 arcsec. Keck should be able to go deeper than HST, and the new Gemini
telescopes should also go deeper and achieve better seeing than CFHT.
Time has eroded much of the original advantages of the HST. However, there
are still some projects that remain the exclusive domain of the HST, mainly
those to do with very high resolution but not excessively faint.

Phil

--
Phil Fischer                         | Hamilton, Ont.
[e-mail]   | Canada
Dept. of Physics and Astronomy       | L8S 4M1
McMaster University                  | 416-525-9140 X 4574

------------------------------

Date: Thu, 10 Dec 1992 23:44:59 GMT
From: Brad Whitehurst <[e-mail]>
Subject: what the little bird told Henry
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>>In article <[e-mail]> [e-mail] ("Phil G. Fraering") writes:
>>>BUT: if the main place where NASP materials seem to be being used is
>>>the heat shielding, and its re-entry temperature is lower than the
>>>shuttle's, wouldn't shuttle re-entry materials be just as useful?
>>
>>They'd probably work as well, but there is a durability problem.  Having
>>to inspect every last damned tile is the last thing you want to do for a
>>vehicle that's supposed to have rapid turnaround.
>
>They're also heavy as I recall, something you don't need in a SSTO.
>I appreciated the summary you gave earlier, Henry. It looks like they
>have a better test program planned than what has been outlined here
>before. I still think their schedule is extremely optimistic and
>success oriented, but we'll see.
>
>Gary

    Actually, as I recall, the tiles themselves are
featherweights.  Now, the backing and mounting system may add more
weight than one would wish....
    Actually, if the NASP material efforts pan out, it would give
all aerospace/launcher efforts new material options, especially for
load-bearing, high-temp skins and structures.  One prob with the
Shuttle scheme is that the tiles don't bear any structural load (that
I recall).  So you have two (at least) skins...one structural and one
thermal.  If the two functions can be combined in one structure, it
could save considerable weight.  Another reason to keep working on
NASP!  I just wish NASA had the money to do it...it's their kind of
thing...out at the edge of development, but it has become dominated by
the Air Force, since they are paying for it.  NASA security is bad
enough, but DoD is a royal pain, especially for academic research.

--

Brad Whitehurst    |   Aerospace Research Lab
[e-mail] |   We like it hot...and fast.

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End of Space Digest Volume 15 : Issue 535
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