Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_4/V15NO467.TXT

Internet Message Format | 1993-07-13 | 16KB

Date: Sat, 28 Nov 92 05:01:10
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #467
To: Space Digest Readers
Precedence: bulk


Space Digest                Sat, 28 Nov 92       Volume 15 : Issue 467

Today's Topics:
            Clinton's address (was Re: Feynmann's legacy)
                 Comparative Launcher Reliabilities
                       Pumpless Liquid Rocket?
      Shuttle Performance and Titan IV (Was Shuttle Replacement)
                     Shuttle replacement (5 msgs)
                 Source of some Shuttle Requirements

    Welcome to the Space Digest!!  Please send your messages to
    "[e-mail]", and (un)subscription requests of the form
    "Subscribe Space <your name>" to one of these addresses: listserv@uga
    (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle
    (THENET), or [e-mail] (Internet).
----------------------------------------------------------------------

Date: Sat, 28 Nov 92 01:19:24 GMT
From: Craig Fifer <[e-mail]>
Subject: Clinton's address (was Re: Feynmann's legacy)
Newsgroups: sci.space

The Clinton Campaign address on Compuserve is
[e-mail]
which I guess is
75300,3115
if you are on Compuserve.  I have never tried this address, but
maybe it will help someone.

-Craig Fifer
[e-mail]
--
_____________________________________________________________________________
|   Never play leapfrog with              |   Craig Fifer                   |
|   a unicorn!   -Murphy                  |   3736 Heritage Road, S.W.      |
|                                         |   Roanoke, Virginia  24015-4518 |

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

Date: 27 Nov 92  16:05:14
From: [e-mail]
Subject: Comparative Launcher Reliabilities
Newsgroups: sci.space

Josh 'K' Hopkins writes:

>There are ELVs with worse records that shuttle's, but I think there
>are also a few with better records.

  I can't find any.  The latest data I have -- current as about
September is...

     .98  Shuttle (49/50)
     .94  Delta   (200/212)
     .91  Titan   (157/172)
     .90  Ariane  (46/51)
     .89  Long March  (24/27)
     .88  Scout   (99/113)
     .80  Atlas   (208/259)
     .88  Proton  (172/195)

Note there have been several successful launches (Ariane, Long
March, Shuttle, Titan, Scout) since then, and 1 failure (Atlas).
I'll have to get an updated list.

Moreover, this data shows shuttle reliability is even higher if you
compare the differing launch systems at the same maturity.  That is,
to look at the systems reliability after their first N flights.  The
following is from a posting I did to Allen Sherzer in Nov of 1990,
so this data will have to be updated.

    1). Reliability - the shuttle is, I believe, currently 44/45
(.978). Looking at the equivalent past history of ELVs, the Scout
failed 11 of the first 49 launches (1960-66, r=.78), Delta had 3 of
the first 43 fail (1960-1966, r=.93), and Atlas had 9 of the first
42 spacelaunches fail (1962-1977, r=.79) [Sorry, couldn't quickly
find the data for the Titan program history].  Since each  system is
now showing reliabilities in the range of .94-.98, I would conclude
the shuttle system is going through a common trend in space
launchers, known as "infant mortality" where design flaws are found
and fixed, and the system reliability increases.  Rather than throw
in some mathmatical mumbo-jumbo trying to project an increased
reliability for the shuttle, I think we can say the Shuttle system
reliability should increase with time, if the pattern found in
historical launch programs is followed.

 ----------------------------------------------------------------
 Wales Larrison                        Space Technology Investor

--- Maximus 2.00

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

Date: 27 Nov 92 23:41:53 GMT
From: Roger Arnold <[e-mail]>
Subject: Pumpless Liquid Rocket?
Newsgroups: sci.space

[e-mail] (Thomas Clarke) writes:
>I was thinking about the problem of pumping in a liquid fuel rocket
>and wondered if there might be an alternative to fragile turbo pumps
>or heavy pressurized tanks.
>
>Consider:
> [picture and description deleted]
>
>Has this ever been tried?

I doubt it.  Two reasonably solvable problems and a killer:

1) If the density of fuel and oxidizer differ substantially, you've
   got a problem.  The scheme would be workable for kerosene/LOX, but
   totally unsuited for LH2/LOX;

2) You'd need small pressurized buffer tanks at the bottom, to avoid
   severe POGO effects (destructive positive feedback, pressure vs.
   thrust);

3) The mass of structure you need to support the tanks high enough
   above the engines for a given head will allways be greater than the
   mass you'd have to add to the tanks to pressurize them directly.

Otherwise, it's a sound idea.  Don't stop thinking.

--
Roger Arnold
[e-mail]

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

Date: 28 Nov 92 03:50:44 GMT
From: Brian Stuart Thorn <[e-mail]>
Subject: Shuttle Performance and Titan IV (Was Shuttle Replacement)
Newsgroups: sci.space

>Karl Dishaw writes:
>>Has the shuttle ever lifted more than 20 tons (vs. the rated
>>capacity of 30 tons)? ...
>
>   Yes, multiple times.  For example, on each TDRS flight, the
>primary payload (TDRS plus IUS stage, plus support equipment weighed
>about 50,000 lbs in the payload bay.  Plus, now you have to add the
>secondary and other payloads to that total.

      Wales... where on Earth did you get that figure for TDRS/IUS
               weight? According to the official press kit for
               Mission STS-26, the weights were:

               IUS (Inertial Upper Stage) = 32,618 lbs.
               TDRS-C (Tracking & Data-Relay Satellite) = 4,905 lbs.
               ASE (IUS Airborne Support Equipment) = 176 lbs.

               That adds up to 37,699 lbs. No where near 50,000 lbs.

>   As was quoted by Robert Unverzagt from the Titan IV Users Manual,
>the Titan can only put 26,500 lbs into Space Station altitude, with
>no margin reserve [Note: if you assume the yet-to-be-flown SRMUs on
>the Titan-IV, this number increases to about 32,400 lbs.]

      Not by a long shot, Wales.
      According to Aviation Week & Space Technology, 16 March 1992:

      TITAN IV (NO UPPER STAGE): 39,000 lbs. to LEO
      TITAN IV (INERTIAL UPPER STAGE): 49,000 lbs. to LEO
      TITAN IV (CENTAUR): 10,200 lbs. to GEO (that's 22,300 miles)
      TITAN IV (CENTAUR) WITH SOLID ROCKET MOTOR UPDATE: 13,500 lbs to GEO

      This Aviation Week article/graph does not specify precise LEO altitude,
      but 100 miles is unaccountably low.


      -Brian

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

Date: 28 Nov 92 00:30:44 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Brian Stuart Thorn) writes:

>Actually, returning Solar Max to Earth was an option throughout the
>mission...

OK I'll accept that it was technically possible to return Solar Max to
Earth on the LDEF deployment mission.

Now, can you demonstrate that it was cost effective?

>Regarding the 'abort switch' just inches away from an astronaut. Well,
>no, I'm afraid. In 'Men From Earth', Buzz Aldrin describes the Apollo
>abort switch as a handle below and beside the commander's couch. His
>hands were not inches away from it.

It wasn't Aldrin's job to make abort decisions so it comes as no suprise

that the switch was far away from him. On the other hand, Colins in his
book describes how Armstrong's hand was on the abort switch.

>Regarding the RL-10, something went haywire in your message, and I can't
>figure out what you were trying to say.

My point was that of all the RL-10 failures which have occured in the past
10 years (and possibly 20), NONE would have resulted in loss of either a
DC spacecraft or crew.

>However, my argument was that the RL-10, which will power the DCX, has
>failed twice in flight in the past 18 months.

If the same failures happen to DCX then all they need do is shut down the
engines which did start, find and fix the problem, and fly again. This will
result in RL-10's with one less malfunction and a more reliable system.

>Further, one of the few
>other cryogenic engines, Saturn's J-2, had a two-engine failure on at
>least one mission (Apollo 6, April 4 1967) and I believe also on Apollo 13.
>I'm not saying that the DCX is dangerous because of it's RL-10s, but
>these facts should at least give it's engineers pause.

Sure. I'm not saying that the first few SSTOs will be as reliable as
today's airliners. What I am saying is that they will be far more reliable
than either existing spacecraft early airliners. Eventually they will
be just as reliable as modern ariliners.

   Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------148 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Fri, 27 Nov 92 19:52:57 PST
From: Brian Stuart Thorn <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

>>Regarding the 'abort switch' just inches away from an astronaut. Well,
>>no, I'm afraid. In 'Men From Earth', Buzz Aldrin describes the Apollo
>>abort switch as a handle below and beside the commander's couch. His
>>hands were not inches away from it.
>
>It wasn't Aldrin's job to make abort decisions so it comes as no suprise
>that the switch was far away from him. On the other hand, Colins in his
>book describes how Armstrong's hand was on the abort switch.
>
     Sorry, I'm not a writer here. I meant to say that the COMMANDER's
     (Armstrong's) hand was *not* on the abort switch. I wasn't implying
     that Aldrin was to use the Abort switch. Hmm... I'll have to dig up
     my copy of 'Carrying the Fire' again...


     -Brian

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

Date: 28 Nov 92 03:52:23 GMT
From: Brian Stuart Thorn <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

>On the mission in question Shuttle did little if anything else.

      The mission in question launched two communications satellites for
      paying customers first, Allen, and only then did it retrieve the
      two derelict HS376s.

      -Brian

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

Date: Sat, 28 Nov 1992 04:18:16 GMT
From: Jonathan Hardwick <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

[e-mail] (Brian Stuart Thorn) writes
> [e-mail] (Gary Coffman) writes:
> >remember it is a piloted
> >powered vehicle.  if the ILS screws, the crew is still able to visualy
> >guide as well as get instructions from ground control.
>
>      At Mach 24, it doesn't take long for things to get out of hand.
>      Remember that Scott Carpenter missed his landing zone by so much
>      that Walter Cronkite was about to pronounce him gone. There are
>      many incidences of off-target returns in the Russian space
>      program too. What would that do to Delta Clipper?

Delta Clipper comes down under power.  Power == cross-range ability.
If something screws up and you look like you're going to hit 50 miles
off, you can correct your trajectory on the way down.  Walter Cronkite
would be blathering on about the majestic spacecraft settling gently
before him on a pillar of smoke and fire, rather than wondering where
the spam-in-a-can had impacted.

>     ("Ah! Set her
>      down in Golden Gate Park! Everybody remember where we parked!")

Beats the shuttle.  "Ah!  Set her down in Golden State Park!  Tell the
people on the ground to clear a 2-mile-long swathe.  Remember to get
it right on the first try, because we've got the flight
characteristics of a dying swan and can't turn around.  The orbiter
will be a write-off for sure, but we *might just survive*.  With a bit
more luck, we won't kill anyone else in the process!"

I know which one I'd rather be riding.  I know which one I'd rather
have coming down somewhere over my head.

Jonathan H.

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

Date: 28 Nov 92 05:34:41 GMT
From: Brian Stuart Thorn <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

If power = cross range ability, then why does the unpowered shuttle have
a 1,000 mile cross-range capability.

Because it has wings and controllability, if not power. If Shuttle is
off course, it still has a shot at a safe landing on a long runway
ssomewhere (not much of a chance, but a chance). If it's headed for
an apartment complex, the pilot can veer away enough to miss.

However, if DCX *loses* power on it's way in, then it becomes a falling
rrock, with *no* control. The pilot or computer would be unable to veer
away from said apartment complex. Look out below.

The Amsterdam 747 disaster has been mentioned much here lately, but in
most cases, pilots have been able to steer a doomed aircraft away from
buildings. The Amsterdam disaster took place at night, when visibility was
poor. The Shuttle rarely lands at night, and presumably neither will
DCX.

I'm sure Allen or Henry will say it momentarily... the DCX is very
unlikely to lose all power on the way in. True enough, but this discussion
appears to be of worst-case scenarios (at least when directed at the
Shuttle) so I chose the worst case scenario for a DCX accident, too.

Oh, any by the way, I and my family live in Rockledge, Florida. Shuttle
KSC landings do indeed come VERY close to flying overhead. I'm not worried,
because if the thing were off course, the Shuttle pilot could point his
(or her, soon) ship into the Indian River or the marshes out west.

-Brian

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

Date: 27 Nov 92  16:04:20
From: [e-mail]
Subject: Source of some Shuttle Requirements
Newsgroups: sci.space

Hi Henry!

>Say I'm a customer.  I don't care *why* it doesn't meet the specs.
>All I know is that it was supposed to be capable of (safely)
>launching my 65000lb payload, but in fact it has never been cleared
>to do so.  I call that not meeting the specs.
>
>(Who am I?  Hint:  I wear a blue uniform, and I *wrote* that
>65000lb requirement.  It was a firm spec, not just a vague
>guideline.)

    Actually, I think you'll find you should be wearing a white lab
coat and speaking with a southern accent.  The 65 Klbs requirement
was driven by a NASA study which set 65 Klbs as the Shuttle
requirement in order to lift a LOX/LH2 reusable "Space Tug".  That
was part of a set of studies which were informally called the
"Hydrogen Economy" since they assumed everything was to be LOX/LH2
powered.
   The DoD did set three of the basic shuttle requirements:
   - 60 foot payload pay length  -- driven by an unspecified
requirement, but assumed to be related to focal length of a payload
when attached to a unspecified common upper stage.
   - The cross range requirement -- set to allow a once around
mission from VAFB into polar orbit.
   - 32 Klbs into Polar orbit from VAFB. Note this is not the same
as 65 Klbs from KSC, since the orbit altitude and inclination were
specified as different.  This translates, roughly, into about a 70-
72 Klb payload from KSC.  This mission was the driver for the 109%
engines, the filament wound SRBs, and a couple of other mods for the
shuttle system that were quietly dropped when VAFB flight
requirements were dropped.
    Good references on where these design decisions were made and
from whence they came from can be found in ...

    "Enterprise" by J. Grey (avail in most large public libraries)
    "The Decision to Develop the Space Shuttle", by J.M. Logsdon,
Space Policy, May 1986
    " The Space Shuttle Program: A Policy Failure?", Science, 30 May
1986
    "Engineering Design and Political Choice: the Space Shuttle
1969-1972", by S.N. Pace published as an AIAA historical paper 1984,
and as a MIT master's thesis, 1982

 -----------------------------------------------------------------
 Wales Larrison                         Space Technology Investor

--- Maximus 2.00

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

End of Space Digest Volume 15 : Issue 467
------------------------------