Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_4/V15NO451.TXT

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Date: Tue, 24 Nov 92 05:04:29
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #451
To: Space Digest Readers
Precedence: bulk


Space Digest                Tue, 24 Nov 92       Volume 15 : Issue 451

Today's Topics:
               ...and another golden oldie... (2 msgs)
            Another in the continuing Golden Oldies series
                         Dyson Spheres, again
     golden oldie: jep on "Shuttle's and laser launching system"
                      golden oldie: launch idea
                   golden oldie: more on spaceports
                      golden oldie: nasa budget
             golden oldie: Shuttling off the mortal coil
                           Golden Oldies...
              golden oldies: Advanced Rockets and SSTO's
            Looking form information about Martin Marietta
                   Pumpless Liquid Rocket? (2 msgs)
                       Shuttle Landing Schedule
                     Shuttle Replacement (2 msgs)

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

Date: Mon, 23 Nov 92 15:46:44 -0600
From: [e-mail] (Phil G. Fraering)
Subject: ...and another golden oldie...

     The NAA and its Sky Shuttle, obviously a reference to NASA and
the Space Shuttle, is not a valid analogy.  The reason is simple:
it is very easy to build a scale model of a bridge out of balsa
wood, but you must use a qualitatively different material when
building the real thing.  In case you didn't follow that, I'll
rephrase it:  scale is very important.

     There is a very real difference in scale between the fictic-
tious Sky Shuttle, an airplane, and the Space Shuttle, a space
ship.  An airplane is such a simple device, in its most primitive
form, that one can be built single-handedly with the resources
available to a single person.  Thus, the Wright brothers were able
to pioneer in the field without any financial backing.  The Space
Shuttle, on the other hand, is one of the most complex machines
ever built by man to date (even if it will look hopelessly primi-
tive some day in the future).

     The moral of the Sky Shuttle scenario is that space travel
would be better developed by tinkers working in their backyards,
or, more realistically, by major corporations.  However, the simple
fact is that the Space Shuttle is too complex a machine to be
/developed/ by any corporation existing today.  NO company has the
financial resources to plunge billions of dollars into something
that will take decades to pay itself off.  I am willing to concede,
however, that once space travel has been FIRMLY ESTABLISHED,
private enterprise will be running the space ships under the
equivalent of the airlines' air traffic control system, and I do
support NASA's plan to eventually sell its shuttles.


Note from phil: god, didn't any of these people use .signatures?
BTW, nice how "NASA's plan to eventually sell its shuttles" worked
out, huh?













--
Phil Fraering
"...drag them, kicking and screaming, into the Century of the Fruitbat."
<<- Terry Pratchett, _Reaper Man_

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

Date: Mon, 23 Nov 92 15:50:20 -0600
From: [e-mail] (Phil G. Fraering)
Subject: ...and another golden oldie...

Begin article:

The most recent number I have heard for the marginal cost of a shuttle
flight is $50M, but I don't think this includes an adequate allowance for
the ground support. To round up for inflation, and to be generally
conservative, assume that the actual marginal cost to a private user would
be about $80M.

I have seen first cut designs for a passenger module for the shuttle that
would pack about 60 people in like sardines. In addition to being
technically doubtful, that kind of arrangement would significantly reduce
the market for some kinds of travel (vacation in particular). If you allow
a reasonable amount of room for support equipment, a bar, and the like, a
passenger capacity of 20 is probably believable, which would yield a per
person cost of #$2M.

This, of course, doesn't take into account the purchase of the passenger
module, much less it's development cost. I guess my vacation in space will
just have to wait a few years.

TCS

End article.

Comments: at last, someone with a .signature. And a solid number
for space shuttle costs... NOT!

Although to quote an old song, I wish I didn't know now what I
didn't know then...

pgf





--
Phil Fraering
"...drag them, kicking and screaming, into the Century of the Fruitbat."
<<- Terry Pratchett, _Reaper Man_

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

Date: Mon, 23 Nov 92 15:43:46 -0600
From: [e-mail] (Phil G. Fraering)
Subject: Another in the continuing Golden Oldies series

Here's another. Commentary to follow, article begins here:"

    The discussion about private business getting into the space
business in a serious way DOES belong here, because it falls into the
scope of SPACE digest (I feel), and there hasn't been much traffic on
this list recently anyway (things need to be livened up around here).

        To wit:

        While opening space to non-governmental use has potential
dangers, (one can see cost-cutting on safety hardware for a priviate
shuttle, leading to a launch pad explosion or reentry burnup), leaving
it exclusivly in the hands of the government (especially the military)
makes it a political hostage.

        Let me advance another scenario that can happen if the
bureaucratic hold on space is not broken:

        1983 - Furthur budget cuts for NASA cause cancellation of fourth
               Shuttle orbiter. Funds for completion of Discovery (the
               third orbiter) are in doubt. The Air Force steps in and
               pays for the third and fourth orbiters. Congress readily
               approves this "national defense" expenditure.

        1984 - Increased doubts about Shuttle availability and
               reliability (due to trimmed operational funds) lead
               potential customers to use expendable vechiles instead
               (Ariadane for example), cutting income from cargo loads.

        1985 - The Congress wonders why the Shuttle is in such red ink
               and declares "The taxpayers of America cannot afford to
               subsidize this money-losing boondoggle". NASA gives some
               under-booked shuttle flights to the Air Force.

        1987 - Shuttle use has fully replaced expendable rockets for the
               military. Since the military is continually launching new
               spy satellites, plus testing particle-beam weapons,
               Vandenberg AFB is keeping busy while Cape Canerveral is
               winding down.

        1988 - The Shuttle is declared "too vital for national defense
               to be used for other things", since the military now
               leans heavily on it (and they have the bucks to
               do so), so NASA is reduced to buying cargo bay space from
               the Air Force to do science.

        I admit for this pessimistic scenario to take place, a lot of
things have to go wrong in the next year or two. I neither expect nor
desire these things to happen. However, if space remains, as it is now,
exclusively in the hands of the government, this CAN happen, and there
will be no failsafe against it.

        A solution is to open up space to private speculation (with
proper licensing and [gasp] regulations). In the interim, the money for
the R&D must continue to flow from the taxpayers to build the basic
technology for space industrialization (the Shuttle).

        Alright, folks.... let's see those brickbats fly!
-------

Phil here again: what do we know from here in the future?
Basically, the shuttle has turned out to be an expensive
waste of money that Proxmire couldn't even conceive of,
and we can't even get rid of the danged thing if that's
what it took to save the space program.

I mean in terms of having a space program that does something,
not just spend money...

--
Phil Fraering
"...drag them, kicking and screaming, into the Century of the Fruitbat."
<<- Terry Pratchett, _Reaper Man_

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

Date: 23 Nov 92 20:52:14 GMT
From: Henry Spencer <[e-mail]>
Subject: Dyson Spheres, again
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Frederick A. Ringwald) writes:
>> Well, Dyson himself did not actually propose a solid sphere...
>> What he invisioned was a large number
>> of habitats in orbit about a star which, together, would completely
>> encircle the star in a ball-of-twine formation...
>
>Have you read Dyson's original article? I have it here in front of me...
>This sounds like a solid sphere to me...
>...the idea of a swarm of independent space habitats wasn't
>Freeman Dyson's, it was Gerard O'Neil's, circa the late '60s...

Sorry, not so.  Dyson's *original* paper demonstrated the adequacy of the
supply of materials by postulating a solid sphere, but he followed up on
that with more detailed discussions which specified a swarm of smaller
bodies.  See his paper "The Search for Extraterrestrial Technology" in
Perspectives in Modern Physics (R.E. Marshak, ed.), published in 1966.
(I've seen references to the same material appearing in a talk given
by Dyson somewhat earlier.)

O'Neill's key contribution was not so much the idea of space colonies, but
the observation that space is a *better* place to live than the surface of
a planet -- that an industrial civilization would *prefer* operating in
open space even if planets were available.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: Mon, 23 Nov 92 16:11:22 -0600
From: [e-mail] (Phil G. Fraering)
Subject: golden oldie: jep on "Shuttle's and laser launching system"

From Jerry Pournelle, on 15 Dec. 1981 (yah, I think I'll start
doing the date on these:

Art Kantrowitz is the new Chairman of the L-5 Society and will
be writing on laser launch systems for the L-5 News.
(Subscribe by sending $20 to L-5 1060 E Elm Tucson AZ 85719)

(I don't get paid nothing nohow for L-5 News)

    NASA has a decision to make: operate stuff, or develop
advanced technology?  There's a conflict.  Worth thinking about.

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


--
Phil Fraering
"...drag them, kicking and screaming, into the Century of the Fruitbat."
<<- Terry Pratchett, _Reaper Man_

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

Date: Mon, 23 Nov 92 16:19:30 -0600
From: [e-mail] (Phil G. Fraering)
Subject: golden oldie: launch idea

Here's yet another: - pgf :

The orbiting linear accelerator article (I thought both the article
and the idea were extremely good) was

Roger D. Arnold and Donald Kingsbury,  The Spaceport,
Part 1: Analog v99 #11  November 1979  pp 48:67  and
Part 2: Analog v99 #12  December 1979  pp 61:77

They propose an accelerator length of 600 km subjecting payloads to
5g, with an active stiffening system on the structure.  Neither the
mass nor the complexity is obviously lower than a cable performing
the same task:  Imagine a cable in low earth orbit that spins in
the plane of the orbit so that the spin just cancels the orbital
velocity at the points where the cable tips come closest to the ground.
The cable is like two spokes of a giant wheel that is rolling on the
earth's surface at orbital speed.  A flying machine can now jump
up and grab the cable end at its lowest and slowest point (for a few
seconds the tip is actually stationary with respect to the ground,
just like the portion of the rim of a rolling wheel in contact with the
ground is momentarily stopped).  The cable can actually enter the
atmosphere (and with terminal guidance and high precision, it could
even kiss the ground), so the job of docking with it is simpler than for
the linear accelerator spaceport.  The payload then hangs on to the end,
and lets the cable flip it around to be flung off at high velocity
later.  At the top of the swing the cable tip is moving at twice
the (orbital) velocity of the cable's center of mass, and if the
payload lets go then, it is sent off with a factor of more that sqrt(2)
beyond escape velocity.  The cable loses some orbital momentum in the
process, wich it can regain from incoming payloads, or high specific
impulse engines at its middle, just like the orbiting linac.

Such a non-anchored skyhook can be build low and spinning fast,
or long and orbiting high and turning slow.  If you build one
to orbit at synchronous height, it has most of the properties of
the synchronous beanstalk.  It turns out that there is a lower
orbit which is optimum in the sense that it minimizes the taper
required by the cable.  The length of such an optimum cable is
one third the diameter of the earth (this is a general principle;
cute, huh?).  So we have the cable about 4000 km long, with its
center orbiting 2000 km above the surface.  With a material
that can make a beanstalk with a taper of 100, we can make an
optimum rolling cable like this with a taper of only 10, using
100 times less material for the same payload capacity.  The
rolling cable can hoist 1/50 of its own mass on each touchdown.
Such touchdowns happen every 20 minutes, in succession at six
equally spaced points around the orbit.  The cable is very long
relative to the depth of the atmosphere, and because of the scale
and the cycloidal shape of the tip trajectory, the cable ends
appear to descend from the sky vertically on each touchdown, with
a continuous upward acceleration of 1.4 g.  They stab downwards into the
atmosphere at a tame 2 km/sec, slow to a dead stop for an instant at
their lowest point, and accelerate gently upwards to leave in the same
way. The tip stays in the atmosphere five minutes each touchdown.

The material of the cable (if graphite) has a tensile strength of
at least 3 million pounds per square inch, so one or two square inches
at the cable ends is certainly sufficient for most tasks. The average
cross section would then be about five square inches.  This gives
the whole rolling skyhook somewhat the scale and geometry of a
typical transatlantic telephone cable, except that the graphite
is five times less massive than the copper and steel of the phone cable.

It seems at least possibly cheaper to me than the accelerator, but cost
analyses would have to decide.  The big advantage of the accelerator
is that it can be engineered entirely with known materials and techniques,
while the cable awaits the next increment in high strength materials.

Re: collisions with aircraft, I agree that most of the time a taut
3 million psi, inch diameter, cable would be to a slow moving aluminum
plane much like a cheese cutter is to a piece of cheese.  Almost all
of the cable is above the atmosphere, however, and a collision at orbital
velocity would be another matter.  The hit probability is no greater
than for a big satellite. The rolling cable is 4000 km long and about
5 cm in diameter.  This gives it the same "frontal" surface area as
a 500 meter diameter sphere.  A collision would not be much of a disaster
on the ground, because the small cable diameter insures that the
cables burns up on reentry (though the sheet of flame across the sky as
several thousand kms burn simultaneously should be interesting).  Still
the cost to the owner (or insurance) and to the payload on the cable
at the time certainly make this event undesirable.  Some kind of
Norad (or coast guard) traffic control or monitoring would seem
worthwhile.  Given a few hours or days warning a skyhook can dodge
a few kilometers, but it will probably be the least maneuverable
object in earth orbit.  It will probably have to be given right of way
most of the time, just as law of the sea gives oil tankers right of way.

Here are a few more skyhook references:

Arthur C. Clarke, The Fountains of Paradise,
    Harcourt, Brace and Jovanovich, 1978.

Charles Sheffield, The Web Between the Worlds, Ace SF, 1979.

Charles Sheffield, How to Build a Beanstalk,
    Destinies Vol 1 #4, Aug-Sep 79, pp 41:68,  Ace books.

Charles Sheffield, Skystalk, Destinies Vol 1 #4, Aug-Sep 79, pp 7:39

Charles Sheffield, Summertide, Destinies Vol 3 #2, Aug 81, pp 16:84


And yet another person doesn't sign his name!

--
Phil Fraering
"...drag them, kicking and screaming, into the Century of the Fruitbat."
<<- Terry Pratchett, _Reaper Man_

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

Date: Mon, 23 Nov 92 16:22:35 -0600
From: [e-mail] (Phil G. Fraering)
Subject: golden oldie: more on spaceports

>Date: 19 December 1981 03:10-EST
>From: Robert Elton Maas <REM at MIT-MC>
>Subject: Spaceports
>To: Hans Moravec at CMU-10A
>cc: SPACE at MIT-MC

Even if the mass and complexity of the 600 km linear accellerator is
the same as the rotating&dipping cable in orbit, the l.a. is much
easier to build. Why? (1) It can be built and tested incrementaly.
Each piece can be installed in sequence and suborbital test flights
of cheap passive material (dirt, rock) can be made. When enough
sections are installed to achieve orbital velocity, it becomes
operational. The dipping cable, on the other hand, must be built
and installed as one big piece somehow. (2) The cable must be put
into space somehow whereas the linear accellerator can be installed
by conventional means such as bulldozers cranes trucks etc. Thus
the linear accellerator can be started now without needing the
shuttle whereas the dipping cable will DETRACT from shuttle payload
capacity by diverting capacity from normal use to cable use, and can't
be started anyway until the shuttle is operational. Thus I don't
think the cable should be done until after we are well out into
space, whereas unemployed construction workers could be assigned
to the accellerator in 1982. We could use the shuttle for delicate
equipment and people, and the linear accellerator for bulk materials.
(I'm not sure whether we should do the Earth-based accellerator now
and use it for bootstrapping ourselves into space industry, or
go instead with the moon-based accellerator which WILL need a
few shuttle payloads to get it installed but possibly be more
effective due to lower moon gravity and lack of atmospheric friction.)
--
Phil Fraering
"...drag them, kicking and screaming, into the Century of the Fruitbat."
<<- Terry Pratchett, _Reaper Man_

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

Date: Mon, 23 Nov 92 16:39:26 -0600
From: [e-mail] (Phil G. Fraering)
Subject: golden oldie: nasa budget

Here's something from Jerry Pournelle on 7 Feb 1982:

There are other developments; and some private work on Big Dumb
Boosters, and the like.  But Single Stage to Orbit technology is
indeed very important, and somewhat overlooked.  It may,
nowever, get funding directly from DOD.


---------------------
--
Phil Fraering
"...drag them, kicking and screaming, into the Century of the Fruitbat."
<<- Terry Pratchett, _Reaper Man_

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

Date: Mon, 23 Nov 92 15:58:55 -0600
From: [e-mail] (Phil G. Fraering)
Subject: golden oldie: Shuttling off the mortal coil

Administrative change: titles of the reposted articles now
appear on the subject line. - Phil. Now here's the article:

        As concerns having 'blown' it by building the Shuttle, I  remind
the audience  that the  Shuttle, although  full of  innovations and  new
hardware, is based in mid-70's  space technology, which IS reliable  AND
proven (unlike  esoteric  methods  such  as  laser  launching  and  mass
drivers).

        It is  obvious  that  chemical  rockets  are  not  going  to  be
sufficent in the long run for  getting places. HOWEVER, that is  exactly
what we are  stuck with  for the time  being.  Of  course, the  esoteric
methods could probably be made to work if a gigabuck or two were  poured
into them, but there is always the  problem of "What if it doesn't  work
on the scale we need it to?"   With current technology, we KNOW it  will
work on the scale involved (up to the scale of the Saturn V).

        While  undoubtedly  politics  were  involved  with  the  Shuttle
winging its  way back  to earth,  that is  ALSO based  on known,  proven
aerodynamic technology.  Also,  an aerodynamic return  vechile has  more
flexibility  on   landing   site   selection   than   the   falling-rock
Mercury/Vostok/Gemini/Vokshod/Apollo/Soyuz genre.

        Face it, there  are LOTS of  things that COULD  have been  done.
But if you were  going to attack the  problem of reusable (cheap)  space
transportation, with  ~2  gigabucks of  taxpayers  money, (and  all  the
political bullshit attached thereto) would you adopt untried  technology
for its base?  No one  wants their  head on a  pole because  of a  wrong
decision, not scientist or engineer or Congressman.

-------
Final comment from Phil: how much have we spent on the Scuttle
since this article was written?

According to the header, it was written by Clyde Hoover.

I need to keep the attributtions straight....

pgf

--
Phil Fraering
"...drag them, kicking and screaming, into the Century of the Fruitbat."
<<- Terry Pratchett, _Reaper Man_

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

Date: Mon, 23 Nov 92 15:36:45 -0600
From: [e-mail] (Phil G. Fraering)
Subject: Golden Oldies...

As I stated before in a message to sci.space that I hope got
through, I've been reading the old space-digest archives.
I'm posting some of the better messages for the perusal
of everyone... and also some of the suprising ones...
Well, here's the first. I wish someone had taken this
more seriously back in '81/'82.

Article begins:

[This item is an excerpt from the November 1981 issue of Reason, a
conservative political journal. It is a sidebar to an article on
goverment vs. private means of developing industry in space. Poli-Sci
is getting a copy because the recent discussion has been on
govermental vs. private means of doing all sorts of things. This item
may be considered a fantasy. Then again...]

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

Imagine...

    Dawn is breaking over the plains of Kansas, a glorious spring
morning in 1982. The rising sun gilds a few clouds in an otherwise
clear sky. In a backyard behind an old, weatherbeaten Midwestern
farmhouse is an incongruous scene: a cluster of modern trailers, with
cables running in all directions, and a large crowd of doers and
onlookers, engineers, reporters, and cameramen. One of the network
reporters is conducting an interview with an older man, clearly by
dress and demeanor a Senior Official.

Reporter Intro: Good morning, Americans.  We are here in Owl's Eye,
  Kansas, to witness another chapter in the forward march of science
  and technology, the controversial and long-awaited "next step" in
  America's costly and exciting conquest of the air.  Today, finally,
  if all goes well, we will see the National Air Administration's
  controversial Sky Shuttle aircraft perform its first applications
  mission as part of NAA's "Skydust" program, in which the mammoth
  aircraft will swoop down over the fields of farmer Ed Shultz and
  spray them with pesticides.  With us today is NAA's deputy
  director, Buzz Wingnut, who will be answering some of the tough
  questions which have come up about NAA and the Sky Shuttle.

    Buzz, what are the chances of success of today's mission?

Official: Well, Jules, all the indications are good.  The weather is
  right, the aircraft, aside from a few minor problems, is in good
  condition, and the crew is in excellent spirits.  It sure looks
  like we have a "go".

Reporter: What about the rotor problems? Everybody knows that the
  rotors have been giving you trouble ever since the start of the Sky
  Shuttle program. Critics have charged that there is still a serious
  chance they'll fall off.

Official: I can assure you that the rotors will not fall off this
  time. The rotor problem has definately been solved.

Reporter: Some critics have questioned the whole idea of having a set
  of rotors on an airplane, saying that the idea of an aircraft that
  can take off vertically \and/ fly 10,000 miles at supersonic speeds
  is unnecessarily complicated. Could these missions be better
  performed by separate aircraft?

Official: Jules, this kind of talk puts our entire technology
  development system in question. I might point out that each of
  those requirements you mentioned, as well as others -- such as the
  ability to land on both land and water, the ability to perform
  aerobatic maneuvers, and the ability to fly at treetop level --
  were inputted to NAA by responsible sectors of the government.
  There is no doubt that each of these capabilities is needed by the
  nation's aviation-using sector.

  As for the idea of developing a separate aircraft for passenger,
  cargo, defense, and scientific purposes, such talk is the height of
  irresponsibility. What with the cost overruns and time delays which
  were unavoidably encountered by the Sky Shuttle program, there is
  no chance of getting Congress to appropriate funds for development
  of a new aircraft in this decade.

Reporter:  Buzz, Senator Buttermore has been highly critical of both
  the Sky Shuttle program in general and the Skydust experimental
  program in particular. He has said, and I quote, "The Skydust
  program has been an enormous boondoggle from the beginning. It is
  mearly an excuse by the NAA administrators to find new 'needs' for
  their services. Ask any farmer -- the idea of spraying chemicals on
  crops from the air as a part of day-to-day agriculture is
  inherently absurd. Both as a Senator and a taxpayer, I say, 'Not a
  penny for this nutty fantasy!'" How do you respond to that, Buzz?

Official: Well, all I can say is that I am glad Queen Isabella didn't
  take this attitude toward Christopher Columbus. "Crop-dusting", as
  our boys like to call it, is an extremely promising technique, and
  one which today's demonstration will prove technologically
  feasible. The Sky Shuttle will reduce the cost of aerial
  application from $500,000 per acre to only $100,000 per acre. I can
  confidently predict that, given Congress's continued support of
  development funding, hundreds, maybe even thousands, of American
  farmers will enjoy the benefits of "crop-dusting" by the year 2000.

Reporter: There have been some voices, so far a distinct minority,
  who have called for private operation of the aircraft program in
  this country, saying that private operators could do the job more
  efficiently. Could you say a few words on that, Buzz?

Official: Well, Jules, it's hardly worth my time to answer that one,
  don't you think? The Sky Shuttle has cost nearly $100 billion
  dollars to develop. Where could a private firm raise that kind of
  capital? We at NAA have always valued the contributions of private
  industry -- we feel that the free-enterprise qualities of our
  contractors demonstrate exactly the kind of government-industry

  partnership it takes to maintain America's leadership in high
  technology. But romantic notions of competing "airlines" operating
  passenger and freight operations across the continent as if they
  were railroads -- that belongs in the 19th century. Aviation in
  America has been in sound hands ever since Congress suppressed
  dangerous cranks like the Wright brothers and created the
  predecessors of the NAA to give American wings, and let us pray to
  God it remains that way, Jules. I'm going to have to cut this
  short. The count-down is entering the final stage.

Reporter: Well, thank you, Buzz and Godspeed. It's a great day to be
  an American.

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

[ Just as a trivia item: the current cost for crop-dusting is under
$10/acre, plus cost of chemicals. ]

Phil Fraering
"...drag them, kicking and screaming, into the Century of the Fruitbat."
<<- Terry Pratchett, _Reaper Man_




--
Phil Fraering
"...drag them, kicking and screaming, into the Century of the Fruitbat."
<<- Terry Pratchett, _Reaper Man_

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

Date: Mon, 23 Nov 92 17:11:59 -0600
From: [e-mail] (Phil G. Fraering)
Subject: golden oldies: Advanced Rockets and SSTO's

This message was posted by some dude named Paul Dietz. ;-)
Anyway, you'll be getting the header for this one, since I've
been forced to abandon the digest peruser for "more" to read
these: they're not in standard digested format. (At least, not
the ones I'm reading now.

Here it is:

Date: 28 Mar 1982 1614-PST
From: Paul Dietz <DIETZ at USC-ECL>
Subject: Advanced Rockets and SSTO's
To: space at MIT-MC

I went to an interesting presentation last night about a new rocket
idea called the Dual Expander rocket engine.  The idea is this: most
of the mass of propellant in a rocket is burned during the first
parts of the launch.  As it turns out, if you want to build a single stage
to orbit vehicle the fuel burned during the first part should NOT
be chosen for high exhaust velocity, but rather for high propellant
density.  Specifically, we should use hydrocarbons (like propane, methane
or kerosene) instead of hydrogen.

The dual expander rocket engine burns both hydrocarbons (propane) and
hydrogen.  It is essentially an engine within an engine.  The interior
engine burns propane and LOX during the first part of the launch with
a chamber pressure of 6000 psia.  It is surrounded by an annular combustion
chamber where hydrogen and LOX are burned.  This outer chamber has a
smaller aperature than the space shuttle main engine, so a smaller
nozzle is needed.  When the center engine is shut down it generates
far less thrust than the SSME, but at that point you don't need much thrust.
The eignine has a top thrust of 1/2 of the SSME, but weighs 1/3 as much.

The speaker presented several designs using the engines.  The first
is an upgraded shuttle.  The SRB's are removed, and the main tank is
enlarged to include a propane tank and extra LH and LOX.  On the bottom
of the tank goes a cluster of (eight?) dual expander engines.  Both
the tank and the orbiter are placed in a stable orbit.  The engines are
removed from the tank and returned inside the shuttle.  If you want
a real heavy lift vehicle, put the SRB's back on.  I forget the exact
figures but this thing lifts well over 100,000 lbs. of payload.  And
you have a tank in orbit to play with.

A one man Air Force shuttle was also described.  It is much smaller
than the space shuttle.  Depending on the exact design, it can be launched
from a C5A or from the ground.  It uses two dual expander engines
and strap on propane tanks that get left in orbit.

Next, several commercial SSTO's.  Three designs were given, the smallest
smaller than the space shuttle, the largest weighing 10,000,000 lb.
and having 29 (!) engines.

The speaker also showed how you can take the proposed airforce shuttle,
put it on an upgraded space shuttle tank and get a vehicle capable
of getting to geosynchronous orbit and back again.  Another proposed
design used LEO refueling from an ordinary shuttle.

The last and most practical design is a disposable SSTO unmanned booster.
It has two dual expanders.  On top goes a second stage that propels the
payload to geosynchronous orbit.  It could carry over 6000 lbs. of payload.
The kicker is this: the first stage is ~14 feet in diameter by 50 some
odd feet long.  These numbers should ring a bell, because the shuttle
cargo bay is 15'x60', making this a "fully reusable disposable".  Final
note on this thing: it can be air-launched from the back of a 747!  This
would avoid dynamic pressure problems.  Launch procedure involves putting
the 747 into a 45 degree climb at 30,000 feet, igniting the rocket and
pulling negative g's to get away.  Boeing is examining putting a SSME
in the tail of a 747 (!) to get it higher.  The launch altitude then
becomes something like 50,000 or 60,000 feet.  This last idea has been
looked at by SAC already; in the 60's they considered putting a Titan
engine in the tail of a B52 to get it away from the field quickly: said
vehicle could be at 30,000 feet 30 miles from the runway in 1 minute!

I hope they get to develope the engine.  It uses no really new
technology.  The speaker claimed it could be developed in 4-5 years at
a cost of $400M (1980).   He works for Aerojet (the company
responsible for this thing) so he isn't unbiased.

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

Phil here again: it now looks like these engines are the wave
of the future: although you have to buy them from the Commonwealth
of Independent States instead.

What did we gain from not developing that engine: 1 (1) flight of
the Space Scuttle...

Phil Fraering
"...drag them, kicking and screaming, into the Century of the Fruitbat."
<<- Terry Pratchett, _Reaper Man_

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

Date: 23 Nov 92 22:15:02 GMT
From: Steven Back <[e-mail]>
Subject: Looking form information about Martin Marietta
Newsgroups: sci.space

I'm looking for information about Martin Marietta, especially the type
of computers they us for.
   1: CAD and space craft design
   2: "Normal" information processing (payroll systems, inventory
systems)
   3: Space Craft check-out stations.
   4: Ground Systems
   5: Technical wordprocessing.
   6: Do they have internet access or are they on a private net.

What would be especially usefull would be some contact names of system
administrators at their various sites.

Thanks
Stevn Back
[e-mail]
[e-mail]

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

Date: 23 Nov 92 20:15:38 GMT
From: Frank Crary <[e-mail]>
Subject: Pumpless Liquid Rocket?
Newsgroups: sci.space

In article <[e-mail]> [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.

>[Description of a gravity-fed rocket deleted.]

>That is connect the tankage to the rocket engine
>with a long pipe.  When accelerating (or at
>rest in a gravity field) hydrostatic pressure
>at bottom of pipe can be fairly high...

This system has two disagvantages: As acceleration changes, the pressure
(and therefore the fuel flow rate and a few other characteristics of
the combustion) will also change; also the system will not function in
zero-gravity.

An alternative is a pressure-fed system: A compressed, inert gas (He and
N are popular) is used to keep the fuel tank at some constant pressure,
and thereby force a flow into the lower pressure combustion chamber.

                                                Frank Crary
                                                CU Boulder

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

Date: 23 Nov 92 21:05:46 GMT
From: Henry Spencer <[e-mail]>
Subject: Pumpless Liquid Rocket?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Thomas Clarke) writes:
>That is connect the tankage to the rocket engine
>with a long pipe.  When accelerating (or at
>rest in a gravity field) hydrostatic pressure
>at bottom of pipe can be fairly high...

The hydrostatic head in the plumbing, while useful -- it figures into the
design calculations for both pump-fed and pressure-fed rockets -- is not
enough to run a pressure-fed engine particularly well.  Even low-performance
pressure-fed engines need 5-10 atmospheres of pressure.  (One atmosphere is
a 10m column of water, and most fuels and oxidizers are substantially less
dense than water.)

I'd also expect stability problems, given the increase in feed pressure as
thrust increases.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: 23 Nov 92 04:56:37 GMT
From: "Mr. Nitro Plastique" <[e-mail]>
Subject: Shuttle Landing Schedule
Newsgroups: sci.space

Could someone please send me a Shuttle Landing Schedule? I'd like to plan a
trip to Edwards for a big group, and need dates for scheduled Edwards landings.



    Thanks in Advance,


*       * ***  *******  *********  *******  ********   *********************
 *     *   *  *       *     *     *       * *       * *                     *
  *   *    *  *             *     *       * ********  *   FIGHT             *
   * *     *  *       *     *     *       * *     *   *        ON           *
    *     ***  *******      *      *******  *      *  *          TROJANS!   *
                                                      *                     *
 *******  ********  *      *     *                    *     *  *****   ******
*       * *       * *       *   *                     *     * *       *
*       * ********  *        * *                      *     *  *****  *
*       * *     *   *         *                       *     * *     * *
 *******  *      *  *******   *                        *****   *****   ******



--
|Victor R. Orly               | "Try to imagine all life as you know it,      |
|aka "Mr. Nitro Plastique"    |  stopping instantaneously, and every molecule |
|Univ. of Southern California |  in your body exploding at the speed of light"|
|Internet: [e-mail]|    -Egon Spengler, from "Ghostbusters"        |

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

Date: 23 Nov 92 19:57:54 GMT
From: Henry Spencer <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space.shuttle,sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>>It's not an accident that the more farsighted schemes for encouraging
>>commercial launchers focus on guaranteeing a market, not on providing
>>direct support.
>
>The problem with a 'Kelly act for space' is that the Government can
>no longer be trusted to maintain the program long enough...

Unfortunately true.  One can think of ways around this, but they're not
things the government is likely to be willing to do...
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: 23 Nov 92 20:56:25 GMT
From: Henry Spencer <[e-mail]>
Subject: Shuttle Replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Karl Dishaw) writes:
>Has the shuttle ever lifted more than 20 tons (vs. the rated capacity
>of 30 tons)? ...

That "rated capacity" is obsolete; the shuttle has never been capable of
lifting that much without violating one operating rule or another.  (Yes,
this means that the original specs were never met.)
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

End of Space Digest Volume 15 : Issue 451
------------------------------