Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_6/V15NO619.TXT

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Date: Fri,  1 Jan 93 05:00:04
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #619
To: Space Digest Readers
Precedence: bulk


Space Digest                Fri,  1 Jan 93       Volume 15 : Issue 619

Today's Topics:
                        averting doom (3 msgs)
                      Clueless Shuttle Questions
                          DC cost estimates
                         fast-track failures
Government-run programs  Was: Re: Justification for the Space Program
         How many flights are Orbiters designed for? (2 msgs)
                           January 3, 1993
                    Latest Pegasus news? (2 msgs)
                        ParaNet Press Release
                      Payload return from orbit
                       SSTO vs 2 stage (4 msgs)
        Stupid Shut Cost arguements (was Re: Terminal Velocity
           Terminal Velocity of DCX? (was Re: Shuttle ...)
                       What was NASA thinking?

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

Date: Thu, 31 Dec 1992 15:31:14 GMT
From: [e-mail]
Subject: averting doom
Newsgroups: sci.astro,sci.space,sci.physics,sci.environment

In article <[e-mail]>,
[e-mail] (Lamont Granquist) writes:

> Hmmmm...  In my ASTR class, we did a rough calculation that showed that the
> radius of the Sun would be quite a bit over one AU after it hits the
> giant branch.  If correct, I don't see how mirrors would help us out.

Different problem.  The concern that started this thread involved the slow
brightening of the Sun while still on the main sequence 1.5 billion years from
now.  The standard solar model predicts the Sun has ~4.5 billion more years
on the main sequence.

As for the back of the envelope calculation you mention, I'll assume it's
the standard one where you're told to assume a red giant of 1 solar mass
with an effective temperature of 4000 K and a luminosity of 10,000 K, then
find for radius.  Using a simple blackbody approximation does indeed yeild
a star of 225 solar radii, or around 156 million km.  But our Sun won't be
getting into this condition until well after it has left the main sequence,
since this condition represents the Sun at the very top of the red giant
branch -- quite far along its evolutionary track from the main sequence.

> Also,
> according to the ASTR class, the Sun isn't going to explode -- it won't be
> hot enough to fuse silicon, and instead it will shed it outer envelope and
> turn into a white dwarf.

As a quibble, while fusion of Si to Fe, and subsequent core collapse, is the
generally accepted mechanism for type II supernovae, this is not the only
way SNe are thought to be produced, even in the case of lone stars.

But for the case of the Sun you are correct in that its mass is too small to
pose any threat of supernova.

-Bill Gawne,  Space Telescope Science Institute

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

Date: 31 Dec 92 16:52:33 GMT
From: James Davis Nicoll <[e-mail]>
Subject: averting doom
Newsgroups: sci.astro,sci.space,sci.physics,sci.environment

In article <[e-mail]> [e-mail] (Lamont Granquist) writes:
>Hmmmm...  In my ASTR class, we did a rough calculation that showed that the
>radius of the Sun would be quite a bit over one AU after it hits the
>giant branch.  If correct, I don't see how mirrors would help us out.  Also,
>according to the ASTR class, the Sun isn't going to explode -- it won't be
>hot enough to fuse silicon, and instead it will shed it outer envelope and
>turn into a white dwarf.

    Hmmm. Anyone know how long it  takes a planet orbiting in the
outer fringes of  a  red giant to evaporate. Granted, red giants are
toasty (By Canadian  standards),  but  wouldn't the plasma  at 1 AU
be pretty thin? How fast would heat/momentum be transfered?

                            James Nicoll

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

Date: Thu, 31 Dec 1992 17:24:12 GMT
From: [e-mail]
Subject: averting doom
Newsgroups: sci.astro,sci.space,sci.physics,sci.environment

In article <[e-mail]>, [e-mail]
I mistakenly wrote:

> with an effective temperature of 4000 K and a luminosity of 10,000 K, then
                                                ^^^^^^^^^^^^^^^^^^^^^^

Which should have been "luminosity of 10,000 L(sun)".  Luminosity is not
measured in Kelvins.

-Bill Gawne,  Space Telescope Science Institute

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

Date: Thu, 31 Dec 1992 11:32:20 -0500
From: Lawrence Curcio <[e-mail]>
Subject: Clueless Shuttle Questions
Newsgroups: sci.space

I recently examined a close-up picture of the Space Shuttle, and I was
puzzled by some of the design features. Please excuse my ignorance but:

1) Why is the tank so blunt? Isn't the shuttle a super-sonic vehicle?
Shouldn't this be sharper, say one of theose secant ogive numbers?

2) Why is the tank so rough? Not only is the texture less than smooth,
but there are a number of grooves near the front as well.

3) The struts that hold the shuttle to the tank are apparently naked
cylenders. Shouldn't these be streamlined in some way?

4)On the side od each SRB, there is a piece of metal running lengthwise.
Is this a strap to hold the segments together?

5) Wouldn't the SRB segments mate more reliably if the propellant grain
from an upper segment extended into the next lower segment? That way,
the propellant segments wouldn't coincide with the chamber segments and
the infamous O-rings wouldn't take as direct a blast. No?

Just curious. Thanks much.

-Larry C.

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

Date: Thu, 31 Dec 92 08:45:19 EST
From: John Roberts <[e-mail]>
Subject: DC cost estimates

-From: [e-mail] (Gary Coffman)
-Subject: Re: Latest Pegasus news?
-Date: 31 Dec 92 00:45:13 GMT
-Organization: Destructive Testing Systems

-In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
[Debate on cost of DC.]

-You misrepresent my position. All I'm saying is that new systems are
-rarely as cheap and easy in metal as they are on paper. That's what
-research and development programs are designed to discover. Only a few
-things that pass through development ever reach mass production as
-cheap and troublefree as they were on paper.

Allen generally takes projected "worst-case" cost estimates for DC
and multiplies them by two or more in making his calculations, which
I think shows he is aware of the problem. That the results still come
out favorable to DC is an indication that work on DC should be continued.
(I presume you favor that.)

I should make one additional point regarding Allen's calculations - they
don't include the large opportunity cost if the Shuttle program should
be cancelled before DC is fully operational (and able to handle the full
operational capabilities of the Shuttle, if that ever happens). Doing so
would add a considerable amount to the cost estimates for DC. So I
consider Allen's calculations to be reasonable, provided that the Shuttle
program is allowed to continue while DC is being developed.

John Roberts
[e-mail]

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

Date: Thu, 31 Dec 92 09:04:00
From: <[e-mail]>
Subject: fast-track failures

Ethan Dicks <[e-mail]> writes:
>FICA payments come from employee "contributions" and from matching
>contributions from the employer.  "Self Employment Tax" is FICA, only
>you pay *both* parts.
>
>Take what ever you are paying (~7%-9%, I forget exactly what) and add in
>an equal amount from your employer.  Now kiss it goodbye, because anyone
>under 50 ain't gonna see it come back :-(
>
>-ethan

Unfortunately, I'm afraid you're right.  I have been going under the
assumption that, when my time comes to retire, there will be no Social
Security.  I will try to support myself with IRAs, investments, retirement
funds, etc.  Don't expect your kids to take you in, they'll probably be
living with you (and you will be supporting them).

And now we hear that the Clinton administration is proposing to push back the
retirement age so that they won't have to pay out so much Social Security.
If the trend continues, by the time I "retire", the retirement age will be
90!

Rick Kitchen
[e-mail]

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

Date: Thu, 31 Dec 1992 15:56:18 GMT
From: "Dr. Norman J. LaFave" <[e-mail]>
Subject: Government-run programs  Was: Re: Justification for the Space Program
Newsgroups: sci.space,talk.politics.space

In article <[e-mail]> Paul Dietz,
[e-mail] writes:
>Well, Doc, I can't, because I do not recall where or just when this
>poll was conducted (it was some years ago).

Here's a clue Paul, the results of polls change with time and not all
polls are accurate.

>However, if you wish to
>call me a liar about it, I shall try to cope.

I'm not calling you a liar Paul. However I am a scientist, and as a
scientist,
I like to make my own judgements.

Norman

Dr. Norman J. LaFave
Senior Engineer
Lockheed Engineering and Sciences Company




When the going gets weird, the weird turn pro
                               Hunter Thompson

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

Date: 31 Dec 92 15:56:15 GMT
From: "John S. Neff" <[e-mail]>
Subject: How many flights are Orbiters designed for?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Chris Marriott) writes:
>From: [e-mail] (Chris Marriott)
>Subject: How many flights are Orbiters designed for?
>Date: Wed, 30 Dec 1992 20:49:25 +0000
>What is the design lifetime of a shuttle orbiter?  ie, how many times is
>it designed to be reused?
>
>Chris
>--
>--------------------------------------------------------------------------
>| Chris Marriott                           | [e-mail]    |
>| Warrington, UK                           | BIX: cmarriott              |
>| (Still awaiting inspiration              | CIX: cmarriott              |
>|  for a witty .sig .... )                 | CompuServe: 100113,1140     |
>--------------------------------------------------------------------------
>

I recall an estimate of 50 flights by a NASA spokesman. This may be a
realistic estimate, or it might be optimistic, it is unlikely to be a
pessimistic estimate. This number is consistent with the statement that
the last shuttle flight will occur in 2007. This statment appears to be
based on the following assumptions: 1) All future shuttle flights will be
successful. 2) The flight rate per year will be increased from three to
four flights per year per shuttle. 3) No further shuttles will be built.
4) The lifetime of a shuttle is 50 flights.

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

Date: Thu, 31 Dec 1992 17:17:02 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: How many flights are Orbiters designed for?
Newsgroups: sci.space

In <[e-mail]> [e-mail] (John S. Neff) writes:

>I recall an estimate of 50 flights by a NASA spokesman.

The politically (but not necessarily technically) correct line
is now that "the Shuttle orbiters will last for longer than their
original 100-mission design life."

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

Date: 30 Dec 92 22:21:01 GMT
From: Michael Corbin <[e-mail]>
Subject: January 3, 1993
Newsgroups: sci.space

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--
Michael Corbin - via ParaNet node 1:104/422
UUCP: !scicom!paranet!User_Name
INTERNET: [e-mail]

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

Date: Thu, 31 Dec 1992 16:44:26 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: Latest Pegasus news?
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Gary Coffman) writes:

>You misrepresent my position. All I'm saying is that new systems are
>rarely as cheap and easy in metal as they are on paper.

You're setting up another strawman, Gary.  No one ever said that
building launch vehicles was cheap or easy.  If it was, teenagers
would be building them in the family garage.

IMHO, anyone, in any industry, who believes a million dollars is
a small amount of money deserves a pink slip.

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

Date: Thu, 31 Dec 1992 18:24:05 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Latest Pegasus news?
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Gary Coffman) writes:

>You misrepresent my position. All I'm saying is that new systems are
>rarely as cheap and easy in metal as they are on paper.

Gary, I refer you to my recent posting where I compared DC costs to
Shuttle costs. I encoumbered DC with development costs but not Shuttle.
I doubled DC's DDT&E, production and operations costs. It still came up
a winner.

Nobody is saying it will be a piece of cake. Are you saying that a factor
of two isn't enough to cover the risk? If not, then what's your point?

  Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------114 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 30 Dec 92 19:07:04 GMT
From: Michael Corbin <[e-mail]>
Subject: ParaNet Press Release
Newsgroups: sci.space

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--
Michael Corbin - via ParaNet node 1:104/422
UUCP: !scicom!paranet!User_Name
INTERNET: [e-mail]

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

Date: Thu, 31 Dec 92 08:24:25 EST
From: John Roberts <[e-mail]>
Subject: Payload return from orbit

-From: [e-mail]
-Subject: Re: Stupid Shut Cost arguements (was Re: Terminal Velocity
-Date: 31 Dec 92 02:05:00 GMT
-Organization: University of Houston

-In article <[e-mail]>, [e-mail] (Allen W. Sherzer) writes...
->>    GRO and UARS are both candidates for return to earth.
->
->Doing that would cost more then they are worth. It would be cheaper to
->build new ones and launch them commercially.

-I would dearly love to see your cost analysis on this Allen. Since the
-marginal cost for a Shuttle mission is only 37 million dollars, this is
-what it would cost for a reflight.

I think it would be more fair to use the $400-500 million figure, unless
there just happens to be a time slot where there's an orbiter available
but no other payload ready. It might be more worthwhile to use such a slot
to refly ASTRO or TSS.

-By the way your Titan IV cannot lift
-a payload like HST due to its adverse dynamic envelope.

So what is the dynamic envelope of Titan IV?

->>    The Hubble repair could still prove too much for orbiting
->>    astronauts and thus require return to Earth for mirror replacement,
->
->No for two reasons: 1) it would be cheaper to build another and fly it
->and 2) in testimony before the House the program manager said Hubble
->wouldn't survive the return trip.

-For 1) see the above. For 2) from what I have heard from the HST program
-manager at Marshall, they could bring it back down. That is a contingency if
-the solar array replacement goes awry.

I think the general attitude is that HST could *probably* be returned safely,
but they would greatly prefer not to, for a variety of reasons.

John Roberts
[e-mail]

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

Date: Thu, 31 Dec 1992 16:54:07 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: SSTO vs 2 stage
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Paul Dietz) writes:

>No, what you did was deride a careful and thoughtful analysis by Bruce
>Dunn by offering a strained analogy between aircraft and spacecraft.
>I merely pointed out your analogy was flawed.

Oh?  Well, let me try again.  The main cost component for reuseable
launch vehicles is not fuel, or even fabrication costs, but maintenance.
This is even more true for space launchers than for aircraft.  Bruce
offered a careful and thoughtful analysis that would reduce fabrication
and fuel costs (*if* you accept his handwaving assertion that the lower
stage would cost less per pound to manufacture) while enormously increasing
the already-greater maintenance costs.

Now, please point out to me where my analogy is flawed.

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

Date: Thu, 31 Dec 1992 17:01:33 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: SSTO vs 2 stage
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Bruce Dunn) writes:

>        This somewhat confuses the issue, in that it tends to imply that the
>technology necessary to build a DC-1 was available a generation ago.

Nope.  It clarifies the issue because the technology to build a DC-1
(or Hyperion, as McDonnell Douglas called its SSTO back then) was available
a generation ago.  In fact, one of the original Shuttle designs (the SERV
proposal, submitted by Chrystler) was a ballistic SSTO very similar to a
scaled-up DC-1.


>The S-IVB derivative would be a ***non-reusable*** SSTO, which is a different
>animal than a ***reusable*** SSTO.

Then I guess the engineers who called it a reuseable rescue and recovery
vehicle must have been smoking something funny.

In the development stage, the vehicle would have recovered by parachute
and landed "upside down" on extendable legs.

Later, the S-IVB's J-2 engine would have been replaced by an aerospike,
which would double as a heat shield.  The vehicle would then be capable
of reentering and landing "rightside up" and a Gemini capsule would be
added on top for manned missions.

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

Date: Thu, 31 Dec 1992 18:23:58 GMT
From: Paul Dietz <[e-mail]>
Subject: SSTO vs 2 stage
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Edward V. Wright) writes:

> Oh?  Well, let me try again.  The main cost component for reuseable
> launch vehicles is not fuel, or even fabrication costs, but maintenance.
> This is even more true for space launchers than for aircraft.  Bruce
> offered a careful and thoughtful analysis that would reduce fabrication
> and fuel costs (*if* you accept his handwaving assertion that the lower
> stage would cost less per pound to manufacture) while enormously increasing
> the already-greater maintenance costs.


No, he showed that for the cost of maintaining twice the number of
stages, you get about 5 times the payload (the same scheme with
airliners would not give a 5x increase in payload, which shows the
problem with the analogy).

You are apparently tossing in the assumption that stacking will be
very expensive.  This assumption may very well be true, but you have
not justified it.

You have also not brought out the best argument: that TSTO has higher
development cost.  Indeed, even Bruce does not suggest that TSTO be
pursued instead of SSTO, but be kept as a backup or as a follow-on.

    Paul

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

Date: Thu, 31 Dec 1992 18:28:43 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: SSTO vs 2 stage
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Edward V. Wright) writes:

>Now, please point out to me where my analogy is flawed.

I do't think it is flawed so much as missing the point. The point is to
reduce the cost of access to LEO. Bruce's ideas to me seem well thought out
and practical. It cuts costs and reduces risk which is all that matters.

I agree with you that SSTO will eventually be the solution (at least the
way it looks now). That doesn't preclude other options which cut costs and
reduce risk as stepping stones leading in that direction.

    Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------114 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Thu, 31 Dec 1992 18:12:53 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Stupid Shut Cost arguements (was Re: Terminal Velocity
Newsgroups: sci.space

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

>I would dearly love to see your cost analysis on this Allen. Since the
>marginal cost for a Shuttle mission is only 37 million dollars, this is
>what it would cost for a reflight.

I work in the real world Dennis. That means I simply cannot pick and choose,
like you can, which costs I pass on and which I don't. The cost of a Shuttle
flight IS a minimum of $550 million. nothing you say about marginal costs
will change that. Tell us Dennis, exactly who is going to pay the share
of the overhead you have decided not to charge to this mission?

In your world apparently you can simply ignore that flights share of the
overhead. You can['t do that in the commercial world without going out
of buisness.

Do you know what the marginal cost of a Corvette is? I'll bet it's less
than $2,000. When you can persuade General Motors to sell you a new
Corvette for the marginal cost of one then I'll let you use the marginal
cost of a Shuttle flight.

   Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------114 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 31 Dec 1992 18:34:21 GMT
From: Pat <[e-mail]>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>In article <[e-mail]> [e-mail] (Pat) writes:
>>i dont believe the russians have ever been charged with using slave
>>labor.  Now the russians had a strange command economy,  but things still
>>cost, but there were major problems in distribution.  the russian/SU
>>economy was sorta like massachusetts meets new york via sweden.
>>
>
>I agree with all of this. My point was that all those social services,
>which in our system are paid out of worker salaries, were paid out of
>a different account that wasn't charged against their space program.
>So using their numbers is an invalid comparison with numbers from a
>differently organized economy because many of their costs are "hidden"
>in other government accounts. That looks like it's changing, and we
>may soon discover that Russian costs *aren't* really much lower than
>ours for similar launchers.
>



Complaining about socialized economies having strange costing rules
is significantly differennt then stating that the russians
use slave labor.    Certainly comparing DoD costs to Commercial sector
costs to French Costs to Soviet Costs  to Chinese costs  is a difficult
problem.

I am certain that after the re-organization is done, we will discover russian
costs are closer to ours,   but i believe they will be able to provide
launch services cheaper then ours, due to their economies of scale.

Hopefully DC-1 will still remain competitive against their sausage
factory lines.

pat

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

Date: 31 Dec 92 17:21:10 GMT
From: [e-mail]
Subject: What was NASA thinking?
Newsgroups: sci.space

9Wanting to refresh my somewhat rusty remembrance of things rocket,
I picked up "Rocket Propulsion Elements" by George Sutton
(1986, 5th ed, John Wiley and sons).
Therein I found the following interesting numbers:

Space Shuttle Main Engine    Saturn J-2 Upper Stage

Thrust (at alt): 470,000 lbs    230,000 lbs
Specific Imp (alt)   455 sec        426 sec
Dry Weight:         6335 lbs       3454 lbs
Thrust/Weight:          74             67
Mixture Ratio:           6          5.5

Now, I have been led to believe that the SSME is a large
advance over previous engines. The above seems to imply
that with a little work the 6 J-2s could have powered
the shuttle quite nicely.  Perhaps a 6:1 mixture would have
given it the same Isp as SSME - the J-2 thrust and thrust/weight
would have then been 246,000 lbs and 71.5.

Also:

       Space Shuttle SRB         Saturn F-1 First Stage

Thrust(at alt):     2,372,000     1,748,000
Specific Imp:   266 (average)      265 (grnd) - 305 (alt)

Now, the F-1 does not replace an SRB one for one, but its
no too far off.  Given its good record maybe the F-1 could
have been rerated to 135% throttle to equal the SRB.

Hence the question in the title of my post:  What was NASA
thinking about?  Apparently the Saturn engines could have
been used to build the shuttle vehicle.  Why weren't they?

A shuttle with 5 or 6 J-2s using 2 uprated F-1s in the recoverable
boosters would have taken advantage of a history of literally
dozens of successful flight firings.  Plus there would
have been a much wider range of abort modes.

Happy new year.  Let's hope for more rational future design.

--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
[phone], FAX: [phone], [e-mail]

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

End of Space Digest Volume 15 : Issue 619
------------------------------