Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_4/V15NO477.TXT

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Date: Tue,  1 Dec 92 05:04:16
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #477
To: Space Digest Readers
Precedence: bulk


Space Digest                Tue,  1 Dec 92       Volume 15 : Issue 477

Today's Topics:
                          Breasts in zero-g
                FREE-ENERGY TECHNOLOGY For Spacecraft
                     Hubbles's mirror (good spin)
                      Magellan Update - 11/30/92
                   manned vs. unmanned spaceflight
                           Patriot Missile
                             Pop in space
                         Scuttle replacement
                    Shuttle replacement (10 msgs)
           Terminal Velocity of DCX? (was Re: Shuttle ...)

    Welcome to the Space Digest!!  Please send your messages to
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----------------------------------------------------------------------

Date: 30 Nov 92 19:51:25 GMT
From: Legene <[e-mail]>
Subject: Breasts in zero-g
Newsgroups: sci.space

[e-mail] (Magnus Olsson) writes:


>I recall reading somewhere (I think it was in the Omni Space Almanac)
>that NASA was completely unisex: the only difference between the
>clothing of male and female astronauts was that the women wear bras to
>keep their breasts in place.

    I assume this does not include space suits.  Does NASA even have
space suits for females?  Taking care of unexpected potty breaks for
someone in a space suit is supposed to be much easier with a male's
urinary output apparatus.

disclaimer: S.D.S.U. made me say it!

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

Date: 30 Nov 92 09:15:19 GMT
From: Patrick Chester <[e-mail]>
Subject: FREE-ENERGY TECHNOLOGY For Spacecraft
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Ed McCreary) writes:
]
]Aaarrrrrrggghh!  This has got to be the tenth time I've seen
]this damn article!  What gives, do you have a cron job running
]that posts the same five articles every week to random newsgroups?
]
]Give it a rest or at least post something new!
]

Check sci.skeptic and think of that Chinese saying:

"Be careful what you ask for, you may get it."

--
Patrick Chester            |----------------------------------------------------
[e-mail] |"The earth is too fragile a basket in which to keep
Politically Incorrect      |  all your eggs." Robert A. Heinlein
Future Lunar Colonist      |"The meek can *have* the Earth. The rest of us are
#^%$!! Militarist          |  going to the stars." Robert A. Heinlein
(Of the Sun Tzu mentality) |----------------------------------------------------

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

Date: 30 Nov 92 19:24:06 GMT
From: "G. Scott Smith" <[e-mail]>
Subject: Hubbles's mirror (good spin)
Newsgroups: sci.astro,sci.space

In article <[e-mail]> [e-mail] (Greg Wilkins) writes:
>
>What are the chances that hubble would have flown if the flaw in the mirror
>was detected?
There exists a second mirror made by another contractor.  The mirror would
have been replaced and the mission flown.
>
>If there was a chance that hubble would have been grounded, maybe it is
>better that it went up half blind (but fixable).  The science learned from
>fixing it in orbit must also be worth something -> probably will save an
>extra flight practising for Fred.
If the problem had been found, it would have been fixed and the vehicle
flown.  You don't spend several billion dollars and not fly the thing.
Making another mirror would be cheaper than canceling the program, even
if there wasn't another mirror already made.

--
Scott Smith                     |Ozman's First Law: If someone says he will do
                                |                   something "without fail",
                                |                   they won't.

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

Date: 1 Dec 92 05:55:42 GMT
From: Ron Baalke <[e-mail]>
Subject: Magellan Update - 11/30/92
Newsgroups: sci.space,sci.astro,alt.sci.planetary

Forwarded from the Magellan Project

                    MAGELLAN STATUS REPORT
                      November 30, 1992

1.  Magellan continues to operate normally, transmitting a
    carrier plus 40 bps X-band signal which is precisely
    tracked by the DSN (Deep Space Network) stations to
    provide gravity data.

2.  The spacecraft continues to operate under the G2325
    command sequence.  All except two starcals (star
    calibrations) over the 4-day holiday were successful.
    On board counters indicate the occurance of another
    double TWTA (Traveling Wave Tube Amplifier) SSO
    (Spurious Shutoff).

3.  Spacecraft temperatures remain in the expected range.  Bay
    7, which contains the CDS (Command Data Subsystem), is at
    51 degrees C with a cycle depth of 6 degrees.  Transmitter B
    is at 52.7 degrees C which is below the temperature where
    satisfactory performance at 1200 bps is found.

4.  The spacecraft has completed 6211 orbits of Venus; 575 so
    far in Cycle 4, which will end on May 25, 1993.

5.  Doug Griffith, Project Manager, left Saturday for Nagoya,
    Japan, where he will present at paper at the 1993
    International Space Symposium.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Learn to recognize the
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | inconsequential, then
|_____|/  |_|/       |_____|/                     | ignore it.

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

Date: 30 Nov 92 18:54:00 GMT
From: "Dave Batchelor, Space Phys. Data Facil. 301/286-2988" <[e-mail]>
Subject: manned vs. unmanned spaceflight
Newsgroups: sci.astro,sci.space

In article <[e-mail]>, [e-mail] (John David Regehr) writes...
>Sorry if this is a dead subject, but I've only been reading this group for a
>week or so.  I'm writing a paper contrasting manned and unmanned spaceflight.
>I'm in the middle of a couple of books, but I haven't been able to come up
>with a good thesis statement yet.  I would appreciate hearing from people who
>have opinions on the subject, or who can suggest some good reference material.
>I am trying to approach this from a practical and philosophical standpoint,
>rather than detailing the historical controversy on whether the focus of space
>exploration should be on manned or unmanned flights.  Thanks.
>
>-----------------------------------------------------------------------
>John Regehr    [e-mail]
>Kansas State University
>-----------------------------------------------------------------------
>

A fine article on this subject appeared earlier this year in _American
Scientist_.  The title was approximately "An Argument for Manned Space
Exploration."  The basic concept was that critics of manned flight say
automated/robotic missions are safer, cheaper means to achieve the same
scientific returns that manned missions can; however, AI and robotics
are acknowledged by professionals in those fields to be primitive and
very modest in their accomplishments, outside the space probe context.
The author of the article highlighted this logical inconsistency.  Robots
of today and the near future are DUMB and CLUMSY, compared to astronauts.
Why should we risk getting inconclusive or skimpy results from missions
limited to what robots can do or will be able to do in the next few decades?

Examples: the Viking Mars lander could not answer the burning question of
whether life exists on Mars (rather than strange soil chemistry that
resembles life).  Many activities of the astronauts during the lunar
landings would have been far beyond the capabilities of robots then and
in the near future, such as retrieving soil core samples (which happens to
be a very delicate and demanding task).  When the Skylab space station was
disabled by loss of half the solar power arrays during launch, the
astronauts were able to restore it to nearly full functioning, saving a
multi-million dollar spacecraft and returning tremendous scientific
advances in solar physics and other disciplines.  Also, the Hubble Space
Telescope almost had to be rescued by space walkers during its deployment
from the Space Shuttle.

The article gives such examples and really makes its point well: critics of
manned missions actually propose reliance on some very limited technological
substitutes for a human being with a tool kit or some instruments.  And
does anybody explore places like Antarctica with robots?

Enjoy,
])ave
------------------------------------------------------------------------------
Dr. David Batchelor   Space Science Data Operations Office   Mail Code 632
NASA Goddard Space Flight Center  Greenbelt  MD  20771  USA
[e-mail] == &( personal_opinions && !NASA_policy );

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

Date: 30 Nov 92 16:28:12 GMT
From: Brian Weaver <[e-mail]>
Subject: Patriot Missile
Newsgroups: sci.space

The Patriot missle was developed as a aintiaircraft missle
over a long period by the US army , and I believe it was
completed sometime in the late 70's or early 80's.
What was completed previous to the Gulf War was a new
antiballistic version that had a new guidance system capable of
intercepting another missle in flight.

                          Brian Weaver (Dude)
              @swvgs.vak12ed.edu


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

Date: 30 Nov 92 17:38:56 GMT
From: David Toland <[e-mail]>
Subject: Pop in space
Newsgroups: sci.space

[e-mail] (Tor Houghton) wrote:
> If a blob of, say Coke, was floating weightlessly in space (inside a
> spaceship - normal air pressure), would the "fizz bubbles" go from the
> centre to all directions?
[and someone else, I lost the name, discussed nucleation]

An interesting picture that comes to mind is if the drifting blob of
beverage drifts up against a suitable piece of grit.  The fizz is
concentrated at that point on the surface, and the blob goes whizzing
off in the opposite direction, especially if the grit is held by surface
tension for a while.

I don't claim this is anything but idle speculation...

--
--------------------------------------------------------------------------
All opinions are MINE MINE MINE, and not necessarily anyone else's.
[e-mail]   |  "Laddie, you'll be needin' something to wash
                           |  that doon with."

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

Date: 30 Nov 92 17:40:39 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Scuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>>Does anyone remember the pictures of the balloon with four helicopters
>>attached crashing and burning. Control is difficult when your lift
>>comes from several active sources.
[deleted]
>
>Control can be tricky when your lift comes from several *aerodynamic*
>sources.  It's a solved problem when the lift producers are rocket engines,
>which are much easier to control.

I don't think aerodynamics had anything to do with it. It was *throttle*
response synchronization failure that caused the crash. Note the Soviet
booster doesn't use throttlable engines, but DC does. Note that airliners can
have throttle synchronization problems and keep flying because the engines
aren't what's *directly* holding them up. DC doesn't have that luxury.
It's not an impossible problem, but it's another disadvantage of DC
versus horizontal landing systems using wings, or other aerodynamic
devices like lifting bodies, or even VTOL via parachutes. SSTO doesn't
*require* powered VTOL, it's just the way DC is supposed to do it.

Gary

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

Date: 30 Nov 92 16:26:07 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Brian Stuart Thorn) writes:
>>>If the same failures happen to DCX then all they need do is shut down the
>>>engines which did start, find and fix the problem, and fly again. This will
>>>result in RL-10's with one less malfunction and a more reliable system.
>>
>>They're at 10,000 feet, closing fast with the ground, and half their
>>engines don't start (that's what happened in the recent failures). So

>>they just stop the others, get out and fix the problem, and proceed
>>to land? I don't think so. I think they'll smear all over the landscape
>>before they even have time to realize they have a problem. A failure
>>on the pad is one thing. A failure coming down is something altogether
>>different.
>
>>Gary
>
>Uh, Gary... the RL-10s in Atlas-Centaur don't ignite until Centaur does,
>which is after Atlas seperation, about six minutes and several hundred
>thousand feet above the ground. That's alot more than 10,000 ft.

You misunderstand. I'm talking about a DC *landing*, not an Atlas-
Centaur takeoff. The parenthetical expression was meant to convey
that *half* the engines, on the Centaur stage failed to ignite in
the recent failures.

Gary

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

Date: 30 Nov 92 17:30:25 GMT
From: Pat <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Steinn Sigurdsson) writes:
>
>Ooh, I love analogies: so, Allen, would you argue that an Aircraft
>carrier is best left anchored in mid-ocean and the planes flown in?
>After all, it seems silly to sail the thing back and forth all the
>time when what you really want is a launch platform for aircraft
>(somewhere) in the ocean, no?
>

Actually that is how carriers operate.  the air wings fly off as the carrier
approaches home port so they can under go depot level service.  also
that way they are available for other ops while the carrier refits.

the carrier then steams off shore and the wings are flown on.

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

Date: 30 Nov 92 19:11:30 GMT
From: Dave Michelson <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>
>>I recall at least one case (Apollo? Gemini?) where
>>one of the astronauts was faced with data suggesting this decision might be
>>required - it's not an easy one.
>
>I believe it was Guss Grissom. The engines on their Titan launcher ignighted
>and then shut down after the control panel indicated liftoff had occured. If
>the panel was correct and they didn't punch out, they would be dead 1/10 of
>a second later. Grissom however felt that "it felt solid beneath" and
>made the correct decision not to eject.

This has come up *so* often during the past six months that everyone
should it straight by now....

The flight was Gemini 6A.  The command pilot was Wally Schirra.  The date
was December 1965.

'Nuff said.

--
Dave Michelson
[e-mail]

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

Date: 30 Nov 92 17:58:39 GMT
From: Pat <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

>>>
>>remember it is a piloted
>>powered vehicle.  if the ILS screws, the crew is still able to visualy
>>guide as well as get instructions from ground control.
>
>     At Mach 24, it doesn't take long for things to get out of hand.
>     Remember that Scott Carpenter missed his landing zone by so much
>     that Walter Cronkite was about to pronounce him gone. There are
>     many incidences of off-target returns in the Russian space
>     program too. What would that do to Delta Clipper? ("Ah! Set her
>     down in Golden Gate Park! Everybody remember where we parked!")
>
Please dont confuse the re-entry phase from the  landing hover phase.
certainly a phine guidance error at re-entry results in  hundreds of
miles in terminal descent.  but shuttle has that same problem and you
dont seem to scream about that.  the key point that DC-1 will have
over STS is that when they punch out of the blackout zone they can
get a guidance update from GPS,LORAN, Ground radar or visual and if they
are significantly off course  they cna look for a convenient emergency
descent location and make a powered landing.  Your screwball scenarios
require a guidance failure early in and major loss of control surfaces
or better then 3/4 loss of power.   remember airliners have landed
despite total loss of electronics, or with on board fires or with
loss of major controls  or with all engines gone.  a sufficiently redundant
system induces survivabilty.  certainly wings are a nice way to go
but i think multiple lifting engines is an acceptable mode of landing.

>>Besides, a DC flies on LOX/LH.  coming in it should be low fuel and
>>LOX/LH does not really explode effficiently.
>
>      Actually, I'd rather it have enough fuel to buzz around in search
>      of a clearing. We don't want a repeat of Apollo 11's 20-seconds-of-
>      fuel-left when they're are populations down here!
>
I would hope that all aircraft  try to land with more then 20 seconds fuel on board.  usually 747s dont land on dry tanks.

>      Besides, most of that explosion we saw on 28 January 1986 was
>      the result of uncontrolled burning of LH2/LOX. I watched that from
>      my back yard, and I wouldn't want one of those on top of Orlando.
>
>      -Brian



You see.  there you go.  proving my point.  what you saw of challenger was
uncontrolled burning.  it didn't detonate it deflagrated.  very impressive
but not the damage of TNT.  Nobody likes a fire,  but firemen dont like
explosions.  and if you dont want one of those on top of orlando, i suggest
you picket the airport.

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

Date: 30 Nov 92 17:05:05 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>
>Please shut up about gliders, Gary, they aren't relevant.

They *are* relevant since that's the Shuttle's landing style. Sure, I'd
rather make a powered landing with the ability to glide as a backup, but
Shuttle can't do that and neither can DC. That doesn't mean that a powered
horizontal landing spacecraft can't be built. The ability to glide is a
major safety backup that DC lacks. The ability to land under power is
a major safety defect of the Shuttle. Neither is an ideal system.

>>... Wind gusts are the worst.
>
>For vehicles relying on aerodynamic lift (wings or rotors), that is.

Even for a bullet. I don't see any magic that makes DC immune to
gusts.

>>... That all takes fuel margin.
>
>Certainly, which is why VTOLs need (and have) fuel margins.  As we've
>been telling you.

Of course you said that the DC lands on nearly empty tanks. Knowing
how fuel hungry rockets are, I was questioning this margin. How many
minutes of hover, or retreat to higher altitude, are available in
those nearly empty tanks? Five minutes? Ten? Airliners declare low
fuel emergencies when they're down to those kinds of margins. If
you're going to treat DC like an airliner, it has to play by airliner
rules. If you want to say this is a hot and risky system like all
other space launchers, then I'll shut up because that's what I've
been trying to say. DC is not like an airliner and can't be treated
like one.

Gary

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

Date: 30 Nov 92 17:17:05 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Bruce Dunn) writes:
>
>For a more accurate comparison with a DC-1 landing, consider that you will be
>landing on a huge flat area which has been cleared of all personnel and
>obstructions.  Furthermore consider that it doesn't matter where on the area
>you land - if there is a gust of wind which pushes the vehicle sideways, you
>will have to do some thrust vectoring to kill the sideways velocity, but
>there is no need to maneuver to regain your original touchdown point.

Well, of course, Bruce, I know this. It's Allen/Henry claims of helicopter
style touchdowns at ordinary airports I'm trying to debunk. Landing at
White Sands or Edwards is a totally different issue with a much larger
margin for error and much less serious consequences in case of disaster.
As long as the DC series sticks to this, I have no complaints. Putting it
down routinely on a small concrete pad in the middle of a metropolitan area
is a totally different thing.

Gary

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

Date: 30 Nov 92 16:46:51 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>
>>They're at 10,000 feet, closing fast with the ground, and half their
>>engines don't start (that's what happened in the recent failures).
>
>Not quite. The engines in question failed on the first attempt to fire them.
>On return the engines would have already fired which greatly increases the
>odds of successful firing.

Or the extra stress they endured during the launch firing put them over
the edge and ensured their failure. Cuts both ways. There isn't enough
flight experience with restarted RL10s to prove the issue one way or
the other.

>I would say this will result in a normal landing.
>
>>different. Yeah I know they're lighter coming down, but asymetric
>>thrust still sounds bad when you're close to the ground and have to
>>make a perfect 4 point touchdown.
>
>You don't need a perfect touchdown.

Perhaps not, but how much list can the DC tolerate and not topple
over? Just where is the CG in relation to the thrust line?

>>Can you gimbel the remaining engines
>>enough to still stay perfectly upright as you descend? Can you do
>>it quickly enough if the failure is close to touchdown?
>
>I would say this is a trivial problem.

Easy for you to say. Demonstrating it's a trivial problem is something
else again.

>>off* in flight. Suppose a fuel feed line fatigues from multiple flights.
>>It wasn't X-rayed before flight because this is airliner grade servicing.
>>So the thing lets go as they pass through 10,000 feet on their way to
>>a landing at O'Hare. A couple of tons of rocket fuel starts streaming
>>down among the firing engines as they pass over the Loop. What's their
>>abort mode?
>
>The engine control system will notice the loss of thruse in the affected
>engine. That engine is shut down.

But the fuel is still streaming out of the break into the hot exhaust
of the other engines. It really doesn't matter if the engine is shut
down by command or not, without it's fuel feed, it's going to quit
anyway. This is an unsurviveable incident *despite* (perhaps *because*)
of all the redundancy in the system. More fuel lines to more engines
multiplies the odds that one will rupture. An old rule of engineering
is that things with less parts have less things to break. Or as we
say in control systems, "two wires make a light."

Gary

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

Date: 30 Nov 92 10:39:08
From: Steinn Sigurdsson <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

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

 Re: DC1

   Total turnaround is expected to cost around $10 million. I have seen figures
   for ground crew size and from memory is was on the order of 10 people.

Not going to be a Union shop, I see!

Now I'm intrigued. I presume the wheels will be slid under the landing
legs and the spacecraft jacked up. That takes you in for payload and
resupply of cunsumables etc., but how do they do the refueling?
Do they fuel it on wheels and truck it over (in which case you need
a 500 ton crawler - those don't come off the shelf do they? - I
presume the wheels should be removed before launch ;-)  - I presume
you don't want launch too close to the tank farm ;-)
or, do they take it unfuelled to the pad and truck the fuel?
It takes what 300 tons LOX and 100 tons LH2? Can you do that with
10 people??? Does your count of 10 include tank farm personnel???

   Note that this will be better understood after the DCX flights.

Yup, the sooner the better...

|  Steinn Sigurdsson    |I saw two shooting stars last night        |
|  Lick Observatory    |I wished on them but they were only satellites    |
| [e-mail] |Is it wrong to wish on space hardware?        |
| "standard disclaimer"    |I wish, I wish, I wish you'd care - B.B. 1983    |

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

Date: 30 Nov 92 20:43:22 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Steinn Sigurdsson) writes:

>Now I'm intrigued. I presume the wheels will be slid under the landing
>legs and the spacecraft jacked up. That takes you in for payload and
>resupply of cunsumables etc., but how do they do the refueling?

It goes something like this:

1. DC lands on its own internal gear
2. Ground crew jacks up gear and inserts weels
3. DC is towed to hanger (if maintenance is needed) or to launch platform
4. DC is placed on launch platform which can support fully loaded and
   fueled DC.
5. Internal landing gear is retracted
6. Payload is integrated
7. DC is fueled
8. Liftoff

 I hope this is less ambiguous.

  Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------145 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 30 Nov 92 22:29:03 GMT
From: "Michael V. Kent" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>
>My question is whether any space launch system
>can accumulate enough flight hours to make any of this analysis meaningful.
>It seems to me that the launch requirement for something of the DC class
>is small enough that there will only be a few built, and those flown
>fairly infrequently. At least they will fly at nowhere near the schedule
>rates of airliners. What I'm questioning here is whether airliner grade
>ground servicing can work with such a system.

Two points should be made here.

1) FAA certification does not necessarily mean certified to enter airliner
service.  Different certification criteria are used for aircraft with differ-
ent functions operated by different organizations.  A Velocity does not have
to meet the same requirements as a 747, yet both can operate out of most
large airports.

The purpose of certifying the DC will be to prove a level of safety consistant
with operating the craft without destruct charges and a few other current
range safety limitations.  This does not necessarily mean it will carry fare-
paying passengers out of O'Hare.

2) DC is not being developed in a vacuum.  The same types of composite struc-
tures, for example, that MCAIR puts in its fighters, DAC puts in its trans-
ports, and Burt Rutan puts into his creations will be used on DC.  That exper-
ience can be applied to Delta Clipper and should ease the technical risk and,
to some extent, the certification requirements.

Again, we don't need to match the maintenance of a 747, just be an order of
magnitude better than the Shuttle, Delta, and Titan.

>Somebody asked, "What's my solution?" to this problem. I mentioned it
>earlier, a much bigger SSTO. Because of cube/square relations, a really
>large SSTO could be built with ordinary structural steels and ordinary
>shipwright techniques. Taking off and landing from the ocean, it poses
>minimal risk to populated areas. Instant heavy lift, and low cost per
>pound to orbit.

Interesting idea -- this might make a good follow-on vehicle after Delta
Clipper puts in a decade of service, and spaceflight becomes routine.  But
for now it is too much too soon.  No SSTO has even made orbit yet.  We will
need DC to shake out the requirements for such a vehicle before we start
scheduling routine flights to DisneyWorld -- Orbit.

>I think DC is an attempt to build an exotic race car when a tramp
>steamer is more in the realm of the possible.

DC-3 was necessarily built before the 747.  Delta Clipper, as currently en-
visioned, will be more of the former, not the latter.  The DC-747 will come
later.  If it's built too soon it becomes a Spruce Goose.

Mike

--
Michael Kent              [e-mail]        Rensselaer Polytechnic Institute
"Interviewing during a recession is a lot like faking an orgasm.  You have to
pretend you're interested all the while getting badly screwed." - Anonymous
Tute-Screwed Aero, Class of '92                               Apple II Forever!

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

Date: 30 Nov 92 18:47:25 GMT
From: Thomas Clarke <[e-mail]>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Thomas
Clarke) writes:
> In article <[e-mail]> [e-mail] (Brian Stuart Thorn)
> writes:
> > However, if DCX *loses* power on it's way in, then it becomes a falling
> > rock, with *no* control. The pilot or computer would be unable to veer
> > away from said apartment complex. Look out below.
> >
> Does anyone know what the terminal velocity of the empty DCX is
> supposed to be?  I heard a figure of 80,000 pounds empty.  If it
> were 20 meters in diameter its weight/area would be about that of
> a human with a terminal velocity circa 100 mph.

An additional thought.  If the DCX's terminal fall velocity is
only 50 meters/second and it weighs 80,000 pounds at landing, then
only about 2000 pounds of fuel are needed to stop its fall;
give it 3 or 4 thousand to be safe.  It would be no fun to be
near if it exploded, but it wouldn't be anything like the average
chemical plant fire.

By the way.  Why not use a parachute to get rid of the final 50
meters per second or so.  Would a chute be lighter than the extra fuel?
--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
[phone], FAX: [phone], [e-mail]

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End of Space Digest Volume 15 : Issue 477
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