Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_4/V15NO472.TXT

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Date: Mon, 30 Nov 92 05:00:03
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #472
To: Space Digest Readers
Precedence: bulk


Space Digest                Mon, 30 Nov 92       Volume 15 : Issue 472

Today's Topics:
                      Evil wicked flying bombs!
               Going out of business launcher sales...
            hypergolics (was Re: Pumpless Liquid Rocket?)
                 Launch Cradles (was: escape systems)
                          ParaNet Directory
                     Shuttle replacement (7 msgs)
                              Simplicity
                            Two stage DC-1

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Date: Sun, 29 Nov 92 21:00:26 GMT
From: [e-mail]
Subject: Evil wicked flying bombs!

> Just a quibble, but it's real damned hard to get a n-weapon to go
off in
> a crash.  This  is a direct correlary of the fact that it's hard to
get
> one to go off at all.
>


Nonetheless, go back and look into Life Magazine circa 1959-1960. An
H-bomb was accidentally dropped. Might have been in North Carolina(?)
There was a good size crater in the photo and  I suspect it spread a
bit of Plutonium around. I think there were comments that only a few
safeties actually held... I also believe some of the charges went off
on impact.


I think they did a bit of work on the safeties after that.

--
=======================================================================
Give generously to the Betty Ford   Dale M. Amon, Libertarian Anarchist
Home for the Politically Correct            [e-mail]
=======================================================================

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

Date: Sun, 29 Nov 92 10:27:27 -0600
From: [e-mail] (Phil G. Fraering)
Subject: Going out of business launcher sales...

In article <[e-mail]> [e-mail] (Brian Stuart Thorn) writes:
[Actually gary]:
>>The companies who went with Shuttle went out of buisness long ago. They
>>paid too much for launch costs.
[Now Brian Thorn]:
>    Wait a second, Allen... I though Shuttle prices were very competitive
>    with Ariane.
[Allen Sherzer]:
\We where referring to a hypothetical situation where Shuttle users paid the
/actual costs. Gary seems to feel Shuttle is worth three times the cost.

\I for one object to having my tax dollars paid to subsidize commercial
/enterprises and snuff out cheaper commercial launchers.

\I can't see it as anything but a big step backwards for us all and I
/don't see why you don't agree.
[bt]:
>Nobody went out of business because they launched on the Space Shuttle.
[aws]:
\That is because they had suckers like us to pay their bills for them.

What about Geostar: didn't the launch delays brought on by
the shuttle program postpone them until after GPS was up,
at which point that was All She Wrote?

--
Phil Fraering
"...drag them, kicking and screaming, into the Century of the Fruitbat."
<<- Terry Pratchett, _Reaper Man_
PGP key available if and when I ever get around to compiling PGP...

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

Date: 29 Nov 92 06:21:30 GMT
From: Andrew Folkins <cuenews!andrew>
Subject: hypergolics (was Re: Pumpless Liquid Rocket?)
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Charles R. Martin) writes:
>In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>
>   If you're willing to settle for a hybrid liquid/solid combination, water
>   and aluminum foil work once you get them started.  Aluminum is difficult
>   to ignite but is a *ferocious* fuel, enough so to rip oxygen out of water
>   molecules.
>
>Oooh, I like the sound of this.  I have this image of Our Hero
>improvising a rocket out of materials available in the USS Enterprize's
>kitchen.  (Old Generation, of course.  NG people would just use the
>replicator.)
>
>What would it take to light it off?  Would thermite be sufficient?

So we're talking about a few grams of thermite, an aluminum frying pan and
a bottle of Perrier?  The last two are easy enough to obtain, but the first
one is a bit tougher...

--
  Andrew Folkins  ...!ersys.edmonton.ab.ca!adec23!ve6mgs!cuenews!andrew
  Newsfeed for the Amiga SIG of the Commodore Users of Edmonton (AmiCUE)

"But that's not a fair comparison.  People like using the Etch-A-Sketch."

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

Date: Sun, 29 Nov 92 13:11:33 EET
From: [e-mail] (F.Baube x554)
Subject: Launch Cradles (was: escape systems)

Brian Stuart Thorn <[e-mail]> mentions:
> Subject: escape systems
>    In fact, when Gemini 6 misfired at T+1 second in 1965,
>    [..] Titan was fully fueled, a few inches off the launch
>    cradle, and the engines had conked-out.

Just out of curiosity, how *are* launchers held and released ?
How is it designed so that a launcher can start off and then
conk out and be "recaptured" ?  Obviously they don't stand
these critters on their engines.

/fred :: [e-mail]

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

Date: 29 Nov 92 01:40:05 GMT
From: Michael Corbin <[e-mail]>
Subject: ParaNet Directory
Newsgroups: sci.space

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

Date: 29 Nov 92 16:33:31 GMT
From: Bruce Dunn <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

Regarding the difficulties of vertical landings, Gary Coffman writes:

> That's funny. We've had to abort helicopter landings many times. Some
> idiot walks out on the pad, some yo-yo parks in our space, a gust of
> wind blows us off course, etc. We often have to hover or go back up a
> ways, look for another spot, try the approach again, even fly around
> for a while until we find one or the pad is cleared. Wind gusts are
> the worst. You almost always have to go back up a ways, get straight,
> and try again.

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.

For those who think that all this is too difficult, remember that it was done
6 times for moon landings, and probably thousands of times in the various
"flying platform" gadgets that the military used to fool with (devices that
flew and hovered by thrust alone).

--
Bruce Dunn    Vancouver, Canada   [e-mail]

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

Date: 29 Nov 92 17:23:17 GMT
From: Jeffrey J Bloch <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

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

.................Stuff Deleted..............

>The only good thing that came out of the Challenger disaster was the
>Pegasus booster system... at last: innovation.
                                    ^^^^^^^^^^^
>(Next spring when it flies, you can add DC to the list)
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
>-Brian

What I'm about to say is my personal opinion and not that of anybody at
LANL, DOE, or anyone else associated with the ALEXIS project....

That said, I would like to comment on this tangential remark in this thread.
Pegasus IS innovation, but the jury is still out on how successful it will
turn out to be. (For our project's sake, we fervently hope it will be highly
successful!) Innovation can introduce bugs into subsystems whose tried
and true methodologies were worked out 20 years ago. The real problem with
these new high-risk innovative systems is that you need a lot of them at
one time being developed in parallel to pay off. If you only have a few,
then there is the inherent contradiction that the first high risk program
HAS to work, or else nobody will do them anymore. Therefore, better, cheaper,
faster, runs headlong into reliability and confidence issues when there aren't
enough high risk programs to spread the risk around.

                            Jeff Bloch
                            Astrophysics and
                              Radiation Measurement
                                Group
                            LANL

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

Date: 29 Nov 92 18:11:10 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <james.723012567@menaik> [e-mail] (James Borynec; AGT Researcher) writes:

>>As I have pointed out, at landing there is not a lot of fuel on board
>>to burn.

>This brings up an interesting point.  What happens if you run out of
>fuel?

That would depend on altitude. One option is to design the hydrogen tank
so it crummples on impact and absorbes energy (as is done with cars today).
That might allow the crew and payload/passengers to survive a fall of some
TBD altitude. Another option is to put a parachute in the nose but I think
that would be more trouble than its worth.

  Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------146 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Sun, 29 Nov 1992 18:36:05 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

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

>> that's not what you said in a previous posting

>Well, I was referring todeep-space probes with four to six-week launch
>windows, not commercial satellites.

Amounts to the same thing. Most of the Shuttle flights which have ever been
scheduled have been cancled. That's not reliable service.

>I believe that Shuttle's performance as an Earth
>satellite launch system was at least as good as any of the expendables
>(again, we aren't talking cost here.)

Read this again and thing about it. You agree that service A and service
B work just as well. Yet service A costs three times as much. I assert
that makes service A not as good.

Again, if it where YOUR money which would you pick?

>In reference to your point that we could have put the satellites on
>expendables and *made* money, I agree! Well, mostly agreee. GD, Mc-D, and
>Martin have yet to make a profit with their expendables.

Maybe if they hadn't been forced to compete with the US government who
was happy to spend OUR money providing subsidies they would be doing
better. At any rate, at least the commercial providers aren't spending
MY money and the money they are spending is REDUCING costs.

>The U.S. poured a heap of money back into those
>systems after Challenger

Not for the commercial launchers. Between GD and Douglas over $1 billion
of THEIR money was spent to get the buisness going. Note that was their
money, not ours.

>mistake. The Shuttle could have returned to service at least a year
>earlier than STS-26, if politics had no intervened

That's like saying we could get to the moon if only gravity whern't in
the way. NASA is a political organization; it can't avoid political
intervention.

That's one reason why it is important that we have a commercial launch
infrastructure so we aren't totally dependant on the wims of politicians.

>(and all that NASA bashing in the press).

No doubt we should all be good little troopers and ignore the problems and
hope they go away!

>The Shuttle started flying again in 1988 *anyway*,
>so, Allen, we didn't save any money by pulling commercial payloads off

But what would have happened if we developed a commercial based infrastructure
back in 1980? Much furthur I'll bet.

>the Shuttle! My point is that if these missions (the non-military missions,
>at least) had each carried three comsats, at least NASA would have made
>*some* money

You don't seem to understand. If you spend more than you take in, you havne't
made anything.

Consider a cab driver who is offered $5 to take a party somewhere. It
costs the driver $10 to make the trip but he figures something is better
than nothing so he aggrees. By your reasoning the driver has made $5 but
by the reasoning of every accountant and cost analyst on the planet the
driver LOST $5.

>(some being better than none, agree?)

Some is better than none but this approach doesn't get us some in the
first place.

>U.S., instead of Europe and China, and we would now be closing in on an
>operational replacement for Space Shuttle. Not bad, eh?

Look, give us the numbers. Show me how much we sill make by selling half
a billion $$ flights for $250 million. Add the cost of this replacement
and see if you can get a sum greater than 0. If you can't then your plan
won't work.

I urge you to add up the numbers and show us.

  Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------146 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Sun, 29 Nov 92 20:19:18 GMT
From: [e-mail]
Subject: shuttle replacement

> weight is 240,000 lb. It also voids RCS and OMS fuel during descent
> so that it lands with nearly dry tanks. Only APU fuel is on board in
> any quanity.

I believe that the APU is burning Nitrogen Tetroxide and Hydrazine? Nasty
stuff, that...

> Lots of physical
> damage in it's path, but no serious fire from Orbiter fuels. There
> might be fire from combustion sources on the ground of course.

>


Note that there is a fleet of specialized craft and crews who drive up to
the shuttle and safe it BEFORE the astronauts exit the craft. This is both
due to danger of explosion or fire as well as the worry about highly toxic
gases. True, a massive explosion of the shuttle is not in the cards. But
neither is the shuttle going to be certified as an airliner, something
which the DC-1 WILL be. I'd not waste my time comparing the DC
operationally to the shuttle. They ain't similar enough to be worth the
effort. Even comparing it with the 747, as we have all been doing is
fairly silly. I'd say the old 707 is probably more in line as far as gross
weight, fuel load and complexity.

Incidentally, I've also been crew on a dicey flight too. Ever spend an
hour debating whether you should try the trees or ditch in the lakes if
you can't make it through the unexpected head winds over the mountains
before becoming you become a glider? The thin strips of lake shoreline
might have been wide enough for a DC-1 to plop down, but they sure as
*HELL* weren't long enough for a Cessna to do anything except clear a
hiking path through the woods. Luckily we made it over the range with a
prayer and fumes. Unpowered landings in any aircraft are dicey affairs.
And if it happens at night you will be damned lucky to find a place to
come down, particularly if you are from the Alleghenies, the "hell strip"
of mail pilot fame. I've walked around more than one airframe sitting on
the edge of a Pennsylvania field, the remnants of the last flight of
someone who could not find a field.

About the only real difference between a crash in a DC (assuming loss of
all power) and a crash in the Alleghenies is that in a light plane in the
Alleghenies you can try to convince yourself you'll find a field at the
last moment, so at least your mind is occupied up to the moment you die.

Just as a multiengine aircraft is safer (assuming proper pilot training)
than a single engine, so is a multiengine spaceship with minimal landing
pad requiements safer than a single or no engine equivalent, or a vehicle
that require miles of runway.

When things go badly wrong, you die. It doesn't matter whether you are in
a Cessna or a 747 or a DC-1. The result is the same.


The shuttle was an historic beginning but its end is nigh. The DC family
is where the future lies.
--
=======================================================================
Give generously to the Betty Ford   Dale M. Amon, Libertarian Anarchist
Home for the Politically Correct            [e-mail]
=======================================================================

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

Date: Sun, 29 Nov 92 20:49:51 GMT
From: [e-mail]
Subject: Shuttle replacement

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


Sometimes yes. A lot of times no. A 747 hit by a terrorist bomb came down on a
Scottish town and took out a huge swath.

A 747 freighter crashed into an apartment block.

An airliner crashed into the bridge over the Potomac and took a few cars with it
into the water.

US, UK and German fighter planes occasionally came down in Germany in
innopportune places. That is why people breathed a sigh of relief over the
decrease in low level operations practice with the end of the cold war.

A jet fighter hit a hotel in the US just a few years ago. The pilot had already
ejected.

A Cessna crashed into a shopping mall.

I can go on and on. Henry and others can add to this list. And yet fighters and
commercial and light planes are still flying. Likewise, DC-1 will someday have
an accident and drop on a building complex. It will do so at the same or a
smaller rate than do the existing vehicles and will cause a similar or lower
level of damage and loss of life to that of the existing vehicles. That is all
that any of us (Alan, me, Henry, etc) are saying. There ain't now or ever been
any form of transport that has perfect safety. My grandmother was barely thrown
out of the way of a runaway horse and buggy when she was a small child. Today we
have an occasional airplane fall out of the sky. In 20 years we'll have an
occasional space ship drop in our back yards. That's the way the world goes
round...

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


The worst case is no worse than the accidents that occur already and will
continue to occur. Shit happens.


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


The problem is that neither you nor I will ever be on board it. There will never
be more than a half dozen of them, and they won't be landing at AGC (where I
first flow) or at Aldergrove (the nearby airport here in Belfast). I'm glad you
get to see the spaceships take off and land. I'd like to be able to do the same.
The DC-1 gives me some hope that *I* will fly before I freeze. It gives me the
hope that the next decade will see kids with wide eyed stares standing outside
the fence to see those ships come down and take off on their pillars of fire at
the local airport. And will stand in awe at the pilots who walk out the gate and
chat with them, and give them a look around the inside of their ship. That is
the sort of future I want to see. The current path of the space program leads to
a future that simply turns my stomach.

I frankly don't give a damn about the shuttle. I can't fly on so it has no value
or utility to me at all. (Well, the pictures are nice, but I'd not bo into a
decline if I didn't have them for my walls and screen backdrops)



--
=======================================================================
Give generously to the Betty Ford   Dale M. Amon, Libertarian Anarchist
Home for the Politically Correct            [e-mail]
=======================================================================

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

Date: Sun, 29 Nov 1992 20:48:20 GMT
From: Paul Dietz <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space.shuttle,sci.space

 In article <[e-mail]> [e-mail] (Henry Spencer) writes:

 >In article <[e-mail]> [e-mail] (Gregory N. Bond) writes:

 >>What are the limits on scaling up something like DC-Y?  My intuitive
 >>guess would be that scaling up should be _easier_...

 >Generally correct.  There's no obvious upper limit.  People have proposed
 >some really huge SSTO designs in the past; most things get easier at large
 >size.  (You can theoretically build a *solid-fuel* SSTO if you make it
 >big enough, I'm told.  Although why you'd want to...)
 >
 >One obvious nuisance is going to be engine development, though.  You can go
 >only so far with clustering; sooner or later you need bigger engines.  Mind
 >you, the ones we've got (or can reconstruct, e.g. the F-1) should suffice
 >for some pretty huge SSTOs...


Actually, the square-cube law *hurts* you as you make launchers
larger.  The thrust from a rocket engine is roughly proportional to
the area of the throat times the chamber pressure.  If you just scale
up a launcher in all dimensions, its weight increases faster than
thrust, and eventually it cannot get off the ground.

Conversely, if you make a launcher smaller, you can get adequate
thrust even at modest chamber pressure.  Witness Hudson's Liberty
unmanned launcher concept, for example.

    Paul F. Dietz
    [e-mail]

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

Date: Sun, 29 Nov 1992 20:07:03 GMT
From: Jonathan Hardwick <[e-mail]>
Subject: Simplicity
Newsgroups: sci.space

[e-mail] (John Roberts) writes
> -From: [e-mail] (Allen W. Sherzer)
> -Shuttle has redundancy but no simplicity. It has more and more complex
> -interfaces which reduces reliability. Reliable systems tend to be ones
> -where a single person can pretty much understand the operation of the
> -entire machine.
>
> "Understandability" may be a more important factor than simplicity as such -
> if a system is understandable, it's easier to spot design errors. But that's
> not the final word on reliability - the human body is (in general) much more
> reliable than any launcher, but also vastly more complex and difficult to
> understand.

The human body is self-correcting to an incredible degree.  Until we
develop machines that are similarly fault-fixing (not just fault-
tolerant), using it as some yardstick of simplicity vs reliability is
bogus.

To put it another way : we can imagine really really complex systems
that will be reliable because they have self-knowledge and can
constantly correct and repair themselves.  But we can't build them.
We're still on the upswing of the complexity vs unreliability graph,
and haven't yet reached the highlands where the line should peak and
then fall rapidly.

Jonathan H.

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

Date: Sun, 29 Nov 1992 17:40:42 GMT
From: Bruce Dunn <[e-mail]>
Subject: Two stage DC-1
Newsgroups: sci.space

The design margins on the hypothetical DC-1 are quite tight.  Consider the
following performance model (1 ton = 1000 kg, LEO assumed to require 9300
m/sec, gravity and air resistance losses included)

Proposed DC-1:

Isp                                        430
Usable Ascent Propellant Fraction          0.91
Liftoff Mass (exclusive of payload)        500 tons
Ascent propellant mass                     455 tons
Structure, landing propellant               45 tons
Payload to LEO                              11 tons


But suppose everything is heavier than expected, and all the weight margins
are used up and the vehicle is still overly heavy.  Assume the extra mass
completely eliminates the payload.  We then have:

Obese DC-1:

Isp                                        430
Usable Ascent Propellant Fraction          0.89
Liftoff Mass (exclusive of payload)        500 tons
Ascent propellant mass                     445 tons
Structure, landing propellant               55 tons
Payload to LEO                               0 tons


It might be thought that the resulting obese DC-1 is a complete failure, and
that all the money spent has been wasted.  However, consider the obese DC-1
not as a SSTO, but as a high performance recoverable second stage for a two
stage system.  What would its performance be with a very low-tech first stage
using LOX/kerosene and existing engines?


Hypothetical first stage:

Isp  (LOX/kerosene)                        300
Usable Ascent Propellant Fraction          0.80
Liftoff Mass (exclusive of payload)       1000 tons
Ascent propellant mass                     800 tons
Structure, landing propellant              200 tons

This can be a really low-tech vehicle.  With care, such a vehicle can be
built with a mass fraction of near 0.95 (the propellants have a bulk density
nearly 3 times that of LOX/LH2).  But there is no need for this - build it
four times heavier than a light weight design, and use the weight to simplify
the design and the structure.  Add lots of redundancy, and a large fuel
margin for landing.  Use 6 ex-Soviet RD-170 engines running at partial
throttle for lift (even at liftoff, four engines at full throttle are
sufficient).  Engines are in a hexagonal arrangement, and any single engine
failure and most two engine failures are not fatal as the other engines can
take up the slack.
For launching the obese DC-1 goes on top of the first stage.  The first stage
climbs in a largely vertical trajectory (to avoid getting too far from the
launching point), accelerating to approximately 1200 m/sec (and incurring
about 800 m/sec gravity losses during the time).  The DC-1 is then staged,
and the first stage returns to the launch site and lands vertically.  The
DC-1 continues to orbit.  Should the DC-1 have engine ignition trouble on
staging, it has both the fuel and thrust to land at the launch site.  With
only some engines working, it can burn off fuel until it has a thrust to
weight ratio of greater than 1, and then land.


The two stage vehicle can place approximately 51 tons in LEO.  Development
costs for this system are higher (two stages need to be built), but:

1) The DC-1 stage does not have to push the margins so much
2) The first stage is really low-tech so should be inexpensive
3) One flight involving the checkout and refueling of 2 stages puts as much
payload into orbit as 5 flights of the original DC-1 concept (with 5
checkouts and refuelings).

The third point suggests that even if the DC-1 is a complete success, if we
ever get serious about putting large amounts of material into orbit, it might
be preferable to build some first stages rather than build more DC-1s.









--
Bruce Dunn    Vancouver, Canada   [e-mail]

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End of Space Digest Volume 15 : Issue 472
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