Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V15_6/V15NO626.ZIP/V15NO626

Internet Message Format | 1993-07-13 | 33KB

Date: Sun,  3 Jan 93 05:00:01
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #626
To: Space Digest Readers
Precedence: bulk


Space Digest                Sun,  3 Jan 93       Volume 15 : Issue 626

Today's Topics:
                       *** BUSSARD RAMSCOOP ***
                 Aerospike Engines... what are they?
                  Aluminum as Rocket Fuel? (2 msgs)
           Galileo's high-gain antenna still stuck (2 msgs)
        How many flights are Orbiters designed for?  (2 msgs)
                       Poker Flats, Alaska UAF
                         russian solar sail?+
                         satellite costs etc.
           Sea floor Planetary Protection really. (2 msgs)
                   Soviet space disaster? (3 msgs)
        Stupid Shut Cost arguements (was Re: Terminal Velocity
                       What was NASA thinking?

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

Date: 2 Jan 93 23:43:05 GMT
From: Henry Spencer <[e-mail]>
Subject: *** BUSSARD RAMSCOOP ***
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Jason Cooper) writes:
>> I don't know exactly how you will get the hydrogen to fuse in the ramjet.
>> So far that problem remains unsolved here on Earth, except for fusion
>> reactions catalyzed by atomic explosions.
>
>The H will be highly compressed by the pressures from the rest of the H
>coming in.  It'll be blocked where it stops by magnetic fields...

Not good enough, alas.  The pressure at the *center of the Sun* produces
only the most sluggish hydrogen reaction -- one that will take billions
of years to consume the Sun's hydrogen supply.

Ordinary hydrogen burns quickly in thermonuclear reactions only under
near-supernova conditions.  The heavier isotopes used in fusion bombs
burn like gasoline by comparison, to the point where they are distinctly
rare in the universe -- even the small supply existing on Earth requires
significant effort to explain.

Building the ramscoop itself is the easy part (difficult though it is).
Getting the hydrogen to *do* something useful, once collected, is hard.
Using it as reaction mass for an antimatter-powered jet engine is going
to be much easier than trying to burn it raw.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 2 Jan 93 14:36:00 PST
From: "RWTMS2::MUNIZB" <[e-mail]>
Subject: Aerospike Engines... what are they?

On Date: Fri,  1 Jan 93 17:02:56 PST, Brian Stuart Thorn <BrianT@cup.
portal.com> writes:
>   Much has been said recently about aerospike engines, specifically
>   in regard to potential use on the DC-1. I've never heard of them
>   before, can someone give me (and anyone else in the dark) a brief
>   description of what an Aerospike Engine is?

Briefly, an aerospike engine uses an exhaust nozzle that can be thought
of as a conventional bell shaped nozzle turned inside-out.  The aerospike
nozzle is a truncated version of an ideal spike;

       Bell           Ideal Spike           Aerospike

       ||||         |------------|       |------------|
      /    \         \          /         \          /
    /        \        \        /           \        /
  /            \       \      /             \______/
                        \    /
                         \  /
                          \/

                               (| indicates the combustion location).

In a bell nozzle combustion gas flow expands outward from the centerline
along the diverging walls.  This is a point design with optimum
performance at one specific ambient pressure (altitude).  Careful design
is needed to achieve desired high altitude performance while avoiding
flow separation at low altitudes which can result in structural damage.
Movable nozzle extentions can provide altitude compensation (larger
exit/throat area ratio at higher altitudes) to overcome some of the
compromise in design.

In an spike nozzle the opposite takes place and the gas flow is directed
inward from an annulus at some diameter away from the centerline.  This
flow is directly exposed to ambient pressure and its expansion is thus
directly coupled to the external environment (continuous altitude
compensation with no moving parts).  Truncating the ideal spike to save
weight results in a bubble of flow at the base which has some performance
loss.  This can be offset by pumping secondary flow (about 1% of primary)
into the base region to elongate the bubble which then forms an
aerodynamic countour similar to the truncated structure (hence the name
"aerospike").

In an earlier post I discussed Rocketdyne's testing of aerospike engines
and compared its efficiency with bell nozzles.

Disclaimer: Opinions stated are solely my own (unless I change my mind).
Ben Muniz, Rocketdyne, SSF Dynamics | "Man will not fly for fifty years"
[e-mail]    |     Wilbur to Orville Wright, 1901

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

Date: Sat, 2 Jan 93 18:30 GMT
From: Karl Dishaw <[e-mail]>
Subject: Aluminum as Rocket Fuel?

>Bruce Dunn writes:
>        This I like!  Molten aluminum (melting point 660 C) can be kept in
>steel tanks.  Using molten aluminum will give a higher Isp than aluminum
>metal.

How's liquid Al going to work in the combustion chamber?

--forming fine droplets will require a new injector plate--how did that
work for the Li-F rocket Bruce mentioned?  What kind of surface
tension does LAl have?  How small would we have to get the droplets to
be?

--will the LAl burn with LOX directly or will it solidify first and then
react?  The rocket's performance will be very sensitive to the
proportion of Al that's burned, by the calculations I ran.  I don't know
how having a mix of liquid and solid aluminum would affect combustion.

--the injector plate is going to need an internal heater to keep the LAl
from solidifying as it passes through and to keep it clean for restarts.
That's definitely going to be an imported-from-Earth item with all its
other requirements.


Karl
sold my soul to Uncle Sam . . . now marked down for resale.

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

Date: 2 Jan 93 20:35:31 GMT
From: Nick Janow <[e-mail]>
Subject: Aluminum as Rocket Fuel?
Newsgroups: sci.space

[e-mail] (Karl Dishaw) writes:

> How's liquid Al going to work in the combustion chamber?
>
> --forming fine droplets will require a new injector plate--how did that
> work for the Li-F rocket Bruce mentioned?  What kind of surface tension
> does LAl have?  How small would we have to get the droplets to be?

Depending on the reaction chamber and throat material and conditions, it
might be possible to use ultrasonics to break the aluminum into fine
droplets.

Hmmm, I vaguely that there are ways to make ultrasonic "whistles".  I don't
know if this could be applied to the injection system, but if it could, it
would at least not require an electrical power source.  It does sound complex
though; hopefully existing injection technology will produce droplets of
sufficiently small size.

I wonder if acoustical energy can somehow be used to protect the surfaces
from accumulation of aluminum oxide?

--

[e-mail]

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

Date: 2 Jan 93 23:29:00 GMT
From: Ron Baalke <[e-mail]>
Subject: Galileo's high-gain antenna still stuck
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Marc N. Barrett) writes...
>   Well, what now?  What else is being planned to free the antenna?  And is
>it expected to work?

The hammering sessions will continue all the way through the entire month
of January, if necessary.  Even though the first hammering attempt didn't
open up the antenna all the way, it did have a postive effect.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Choose a job you love, and
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you'll never have to work
|_____|/  |_|/       |_____|/                     | a day in your life.

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

Date: 3 Jan 93 00:06:19 GMT
From: Joshua Bell <[e-mail]>
Subject: Galileo's high-gain antenna still stuck
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Ron Baalke) writes:
>The hammering sessions will continue all the way through the entire month
>of January, if necessary.  Even though the first hammering attempt didn't
>open up the antenna all the way, it did have a postive effect.

This certainly sounds like a spot of good news. My fingers are
crossed. :)

I am curious about one thing: the contingency plans for the 40 bps
data speed vs the 110,000 (?) bps included a lossy compression
scheme related to JPEG that would allow compression of between 10
to 100 times. If the HGA is freed, allowing the high speed
transmission, will the compression still be used (hopefully with
'a higher Q value') so that even _more_ data than anticipated in
the original mission plan be returned?

Joshua
|         A shimmering net undulating like an infinite borealis.             |
|                                                  - Chapterhouse: Dune      |
|                                                                            |
| [e-mail]  Academic Computing Services, University of Calgary |

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

Date: Sat, 2 Jan 1993 14:16:52 +0000
From: Chris Marriott <[e-mail]>
Subject: How many flights are Orbiters designed for?
Newsgroups: sci.space

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

>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.
>
>

What's due to replace the shuttle in 2007 - the DC?  I *sincerely* hope
that the shuttle fleet won't be "run down" in anticipation of a 2007
cut-off, regardless of whether or not a replacement is *actually*
available by then!  If NASA's historical record is anything to go by,
a replacement due to enter service in 2007 is unlikely to be ready by
then....

Chris
--
--------------------------------------------------------------------------
| Chris Marriott                           | [e-mail]    |
| Warrington, UK                           | BIX: cmarriott              |
| (Still awaiting inspiration              | CIX: cmarriott              |
|  for a witty .sig .... )                 | CompuServe: 100113,1140     |
--------------------------------------------------------------------------


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

Date: 2 Jan 93 17:15:39 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: How many flights are Orbiters designed for?
Newsgroups: sci.space

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

>What's due to replace the shuttle in 2007 - the DC?

NASA people have been responsible for two attempts to kill the DC
program. However, Goldin hasaid that if it works, they will use
it.

>I *sincerely* hope
>that the shuttle fleet won't be "run down" in anticipation of a 2007
>cut-off, regardless of whether or not a replacement is *actually*
>available by then!

That's the rub. Shuttle and NASA procurement process are both so expensive
that there simply isn't any money available for NASA to develope a
replacement.

>If NASA's historical record is anything to go by,
>a replacement due to enter service in 2007 is unlikely to be ready by
>then....

DC could be available long before then *IF* we can get DoD to fund the
proof of concept vehicle.

  Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------112 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 2 Jan 93 17:07:42 CST
From: [e-mail]
Subject: Poker Flats, Alaska UAF
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] writes:
> Does anyone know anything about "Poker Flats" in Alaska..
> Up near Fairbanks, AK.. If I remember right it is run by the
> University of Alaska Fairbanks.. Mostly does atmospheric (northern lights, etc)
> research..
>
>
> Michael Adams
> Alias: Morgoth/Ghost Wheel
> [e-mail]

It is located at mile 29.6 Steese Highway, northeast of Fairbanks, and is
operated by the Geophysical Institute, University of Alaska.  They use it
primarily for auroral and upper atmospheric research for NASA and DOD.  I don't
believe the facility is open to the public although it is not used for
classified research.  They use a Nike solid fuled rocket launched to 60 - 200
mile altitudes often to release barium.  The barium release is visible over
much of Alaska as a green cloud at night.

Don't see too many Alaskans on the net!

Lawrence Bartel
in%"[e-mail]"

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

Date: 2 Jan 93 23:45:49 GMT
From: Henry Spencer <[e-mail]>
Subject: russian solar sail?+
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>... I have heard of the supposed race to the moon with solar
>sails, to celebrate the 500 anniversary of Columbus, not sure if it
>actually came about..

Actually, it was a race to Mars.  It didn't come about; the organizers
flubbed the job of fundraising pretty spectacularly.  It's been revived
as a race to the Moon under somewhat different ground rules.  Timing
and funding is still rather indefinite, last I heard.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 3 Jan 93 00:04:23 GMT
From: Henry Spencer <[e-mail]>
Subject: satellite costs etc.
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>>... you can put the spare satellite in the same
>>orbital slot as the operational one...  Result, no repointing.  Only
>>the control room needs to even *know* which bird is live.
>
>Redundancy is always desirable if it's affordable, but there is a practical
>difficulty with having *cold* spares in orbit. Will they work when we need
>them? They have to be cold spares if they share the same orbital slot and
>frequencies. That's why spare capacity is not operated cold. It's located
>in another spot where it can be kept as a *hot* spare that can be tested...

Testing co-located spares is trivial.  Once a week at midnight (or
whenever is convenient), switch to one of the spares for ten minutes.
Remember, switching among co-located birds does *not* disrupt service
for more than the time taken to turn one off and the other on (or,
worst case, the time taken to do that once, realize that the spare
is not working, and do it again).

>>The big expense
>>of doing most anything in space is getting into LEO; cutting that cost
>>massively makes *everything* more feasible.  It becomes much more
>>attractive to develop a tug capable of bringing things back down from
>>GEO, or a reentry capsule capable of landing a payload too big for a
>>DC cargo bay.  Neither of these devices is technologically difficult...
>
>Well if they're too big for DC, then they can't *get* into LEO in
>the first place by that "cheap" launch method...

I note we have changed the subject; thank you for conceding my point.

As for getting them up there, sure they can:  assemble them in orbit.
On-site assembly is normal practice when device X has to be set up at
location Y but is too big for economical transport there when fully
assembled.  (Of course, in principle you could then disassemble them to
bring them back, but it's not really needed.  Coming down is the easy
part.)

>It's not impossible to deploy mulitple special purpose vehicles in
>space, of course, but cheap as an airliner ticket they ain't.

Cheap as an airliner ticket, no, but much cheaper than even a small
"feeder airline" airliner.  If you can get them into orbit cheaply, it
will be worthwhile to build and operate them.  The vehicles themselves
are not that expensive, especially if you can recover them afterward
for re-use (of subassemblies, at least).
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 2 Jan 93 23:44:00 GMT
From: Ron Baalke <[e-mail]>
Subject: Sea floor Planetary Protection really.
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Ed McCreary) writes...
>On a related note, the designers of Viking were worried that
>the Soviets would land a probe on Mars before their landing without
>following strict sterilization procedures.  This, they felt, might
>contaminate Viking's biological results.  Luckily, the soviets decided
>to follow similar guidlines.

There still is a concern that some of the Soviet spacecraft that made
it to the surface of Mars may have caused some kind of contamination.
The Soviets have said that they have sterilzed their spacecraft, but they
have never disclosed the method of sterilization.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Choose a job you love, and
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you'll never have to work
|_____|/  |_|/       |_____|/                     | a day in your life.

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

Date: 2 Jan 93 23:39:00 GMT
From: Ron Baalke <[e-mail]>
Subject: Sea floor Planetary Protection really.
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Pat) writes...
>I know the Mars Observer orbit was constrained under planetary protection
>guidelines to stay off the surface for X thousand years.

Mars Observer does meet this contraint and will survive in orbit until the
year 2009 with a 99.9% probability, and will survive until 2039 with a
95% probability.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Choose a job you love, and
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you'll never have to work
|_____|/  |_|/       |_____|/                     | a day in your life.

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

Date: 2 Jan 93 11:17:00 GMT
From: Charles Packer <[e-mail]>
Subject: Soviet space disaster?
Newsgroups: soc.history,sci.space,soc.culture.soviet

Somebody told me recently that they had read that the
former Soviet Union had suffered a space disaster in which
they had to leave one of their cosmonauts in orbit to die
because they couldn't rescue him. My informant said that
his information came from reading newspaper accounts of
formerly secret material that was made public in the last
couple of years during the unravelling of the Soviet system
and the subsequent increase in openness of discussion and
publication in Russia.

I don't recall seeing anything about this. I would expect
that it would have been given major coverage in the West
and would have come to my attention. Also, I can't recall
a story to this effect any time in the past thirty years,
though my memory might be hazy.

Can anybody shed light on whether this event did happen?

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

Date: 2 Jan 93 19:37:16 GMT
From: Chris Jones <[e-mail]>
Subject: Soviet space disaster?
Newsgroups: sci.space

In article <[e-mail]>, packer@amarna (Charles Packer) writes:
>Somebody told me recently that they had read that the
>former Soviet Union had suffered a space disaster in which
>they had to leave one of their cosmonauts in orbit to die
>because they couldn't rescue him. My informant said that
>his information came from reading newspaper accounts of
>formerly secret material that was made public in the last
>couple of years during the unravelling of the Soviet system
>and the subsequent increase in openness of discussion and
>publication in Russia.
>
>I don't recall seeing anything about this. I would expect
>that it would have been given major coverage in the West
>and would have come to my attention. Also, I can't recall
>a story to this effect any time in the past thirty years,
>though my memory might be hazy.
>
>Can anybody shed light on whether this event did happen?

Like you, I don't recall anything about this in the last couple of years.  I do
recall that, early in the space era (early sixties), there were persistent
reports of dubious reliability concerning Soviet space disasters which stranded
crews of various sizes in orbit.  As far as I know, the only Soviet in-flight
spaceflight disasters are the two publicly announced ones: Soyuz 1, which
killed its lone occupant, and Soyuz 11, which killed its crew of 3.  In
addition, there was a Soyuz mission which had difficulty during retrofire,
which led to the cosmonauts reentering a day later than planned, a day which
was spent in orbit without the Soyuz orbital module.  This was jettisoned in
preparation for retrofire, and took with it most of the living arrangements
(including the toilet!).

There have been three times the press has resorted to saying that cosmonauts
were stranded in orbit when in fact they were not (in every case the cosmonauts
made successful reentries).  Once was when a Soyuz launch abort prevented a
swap of the Soyuz ferries within the nominal on-orbit lifetime of the ferry.
The cosmonauts later made a problem-free on-schedule reentry using the
"expired" Soyuz.  Another time some fabric insulation came loose from a Soyuz
ferry, and the Soviets stated they were going to repair it before the scheduled
reentry.  However, they were perfectly willing to use the unrepaired spacecraft
to reenter in an emergency, and they did repair it to their satisfaction before
reentry.  The third time is when one cosmonaut had his return flight pushed
back twice due to changing crew assignments.

Soyuz 1, which killed Vladimir Komarov, *might* be the flight which generated
the report to which you refer.  What is known is that Soyuz 1 was launched,
there were no television pictures broadcast from the spacecraft in flight, it
reentered outside a normal Soyuz reentry window, and its crew member did not
survive.  It has been reported that it was in trouble almost from the beginning
of its flight, that at least one of its two solar panels was torn loose as it
entered orbit (explaining the lack of TV pictures), that Komarov had constant
trouble controlling the spacecraft, resulting in the cancellation of the planned
launch of another Soyuz to dock with it for a crew exchange, that he cancelled
two reentry attempts due to being unable to properly align the Soyuz for
retrofire, and that the actual reentry was a desperate affair in which he set
the spacecraft spinning for stabilization and that this spinning indirectly led
to the reported cause of the reentry failure: the shroud lines of his main
parachute tangled and the attempt to deploy the backup chute failed when it
tangled with the main chute.  Unlike the 3 Soyuz 11 cosmonauts, whose bodies
lay in state for several days before interment in the Kremlin wall, Komarov's
interment took place without his body having lain in state.

Like the US, the Soviets also have suffered a number of training accidents,
cosmonauts dying in plane crashes, and cosmonauts dying of natural causes.
They have also had at least three pad accidents which have killed (in total)
multiple hundreds of support personnel.
--
Chris Jones    [e-mail]

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

Date: 2 Jan 93 21:13:02 GMT
From: Ken Arromdee <[e-mail]>
Subject: Soviet space disaster?
Newsgroups: soc.history,sci.space

There's an incident reported by Robert Heinlein in Expanded Universe (published
around 1980 or so, and a revision of a work published in the 1960's) in which
Heinlein describes that on a trip to the USSR, he had heard about some Russian
space vessel which everyone referred to as occupied by a human until the
vessel got in trouble, when everyone suddenly shifted to calling it unmanned.
He wonders if there is a dead Russian in space.

There is also a recent incident where a Russian was stuck in Mir space for
rather longer than necessary because of political reasons (such as having to
send up a Kazakh cosmonaut who wasn't fully trained to take over duties there),
but he was returned to Earth and didn't die.
--
"On the first day after Christmas my truelove served to me...  Leftover Turkey!
On the second day after Christmas my truelove served to me...  Turkey Casserole
    that she made from Leftover Turkey.
[days 3-4 deleted] ...  Flaming Turkey Wings! ...
   -- Pizza Hut commercial (and M*tlu/A*gic bait)

Ken Arromdee ([e-mail], [e-mail])

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

Date: 2 Jan 93 23:12:00 GMT
From: [e-mail]
Subject: Stupid Shut Cost arguements (was Re: Terminal Velocity
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Allen W. Sherzer) writes...
>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?
>

From all of the posts that I have seen in the last few months from you, it
seems that you live in Allen's world. This world is where you pick and choose
your own numbers and play them the way you want to make your systems look
desirable. I have said many times and I say again I support the DC series, it
is just your accounting that are unrealistic, as you forget to charge against
your vehicle, what you so decry me for not doing with the Shuttle.

>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.
>

The simple point that I was trying to make that you totally missed is that
the marginal cost as described in the November 28-December 9 issue of
space news for adding another mission is 37 million dollars maximum. This goes
for all costs directly associated with a shuttle flight including personnel.
I merely pointing out that they could refly for that cost. The overhead would
be there whether they flew the extra mission or not. It is ironic that, if
they did fly an extra flight to refly a payload like we have been speaking
about would lower the amortized cost per mission for the total system.

>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.
>

If GM makes 1000 or 50000 Corvettes, their overhead remains pretty much the
same.  There is a simple formula that is learned in every calculus class that
allows you to predict both the break even point and the optimum point of
production for corvettes to make the most money.

The shuttle, if it had made it's advertized claims  of flying every two weeks
would, if flying commercial payloads, be profitiable, since the marginal
cost of the mission is far less than the cost of competing systems such as
Titan IV and Arianne IV or V.  This is the core problem with shuttle. It does
not fly enough to pay off, in the same manner that if you do not build
enough Corvettes, the overhead in labor, physical plant, and materials will
exceed the profit made on the car resulting in a loss.

It is truly unfortunate that the shuttle will never make its original intended
flight rate, but your comment merely reinforces my point, which is that
the true cost of reflight is cheap relative to using other systems, with the
added bonus that the total system cost is lower due to a higher utilization
factor. The overhead is there whether the system flys or not, as the overhead
at GM is there whether they make cars or not. This is why they are closing
plants, to reduce overhead on marginally profitable or money losing car lines.

Dennis, University of Alabama in Huntsville

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

Date: 2 Jan 93 22:54:00 GMT
From: [e-mail]
Subject: What was NASA thinking?
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] () writes...
>9Wanting to refresh my somewhat rusty remembrance of things rocket,
>
[stuff deleted]

>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.
>

>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.
>

The F1A Engine has been qualified to a flight thrust of 1.75 million lbs. On
the test stand at NASA Marshall Space Flight center the original F1's were
fired to 110% of rated thrust to establish emergency margins (1.65 million lbs).
It is a heck of an engine.

>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 designs

Tom what you are describing IS the original shuttle idea, except that they
wanted to reduce the number of engines and realize "cost savings and airline
type reservicing of the engines". Sound familiar? The original Shuttle would
have basicially been the upper stages of a flyback modification of the Saturn
V first stage. The shuttle with its high ISP LOX/H2 engines would have been
the upper stage. This was the plan before the congressional budget office
and the Office of Budget and Managment (Caspar Weinburger) got ahold of the
shuttle budget.  In order to lower the costs of developemnt to the mandated
development budget, the operational costs of the shuttle were sacrificed.
Wales Larrison posted a wonderful summary of the idiocy that ended up with the
politicans designing the shuttle instead of the rocket scientists.  Most of
the problems that Allen so crys about are the result of that ill considered
budget process.

Dennis, University of Alabama in Huntsville

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End of Space Digest Volume 15 : Issue 626
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