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From: (Dani Eder)
Subject: Re: Space Gun in Jan. Smithsonian
Date: Jan 12 1996
Newsgroups:,, (Jim Kingdon) writes:

>My impression is that it already has a (small) trickle of funding, and
>that the problem is that to build a system which would really reduce
>the uncertainties in a big way would cost billions.  I could be wrong
>about this.

>The other problem is that gun launch is not an all-purpose technology;
>it is not good for large or delicate payloads (e.g. people).  So even
>if successful it wouldn't solve the access to space problem.

Wrong on both counts.  I led a study in 1992 on Gun-Launched Propellant
Delivery System, based on an upgraded version of the SHARP gun.  An
operational system that delivered propellants for GEO satellite
delivery was estimated at $70 million for the gun part.  The SHARP gun
is capable of firing a 5 kg projectile at 4 km/s.  Our gun required
a 600 kg projectile at 5.4 km/s.  We felt that if an intermediate
gun was built (say 50 kg at 5 km/s), that would reduce the project
uncertainties due to startup enough to make a go of it.  The SHARP
gun cost about $3 million to build, and the intermediate gun would be
in the $15 million range.

What our gun would spend it's time doing is launching rocket propellants
in 100 kg lots (the net delivered propellant out of a 600 kg projectile),
at the rate of 1 launch per day.  A large comsat runs about 2 tons,
and requires 6 tons of propellant to get from LEO to GEO, so we could
deliver the fuel for about 6 comsats a year to LEO.  The satellite 
owner could launch the satellite itself for 1/4 the launch cost,
and pay a small amount for the propellant delivery.

As far as access to space, most of what you need in orbit (structural
materials, propellants, air, food) can be launched via gun.  A few
things, like people, computers, and delicate science instruments, need
to be launched more gently, but they represent a small fraction of the
total cargo.

Dani Eder

From: (Dani Eder)
Subject: Re: Lunar Gun
Date: Jan 17 1996
Newsgroups:,, (Filip De Vos) writes:
>Dani Eder ( wrote:

>: is capable of firing a 5 kg projectile at 4 km/s.  Our gun required
>: a 600 kg projectile at 5.4 km/s.  We felt that if an intermediate

>This is enough to launch cargo from the moon now. Payload can be traded 
>for delta v. 
>A gun on the moon is a much more credible engineering-project than an 
>electromagnetic launcher or massdriver: it is technology we understand 

But we are not on the Moon right now.  We are on Earth.  First we
have to figure out cheap ways of getting stuff off the Earth.  The
Moon is small enough that almost anything can be used to launch things
from it.  But worry about it when we get there.

>The only problem I can think of for the Lunar Gun is the lack of 
>Nitrogen on the moon. My knowledge of explosives and propellants is 
>tenuous, but I think most charges/powders contain nitrogen in significant 

The SHARP gun, the one I worked on the design of, and most high
speed guns use hot hydrogen as the working fluid.  The SHARP gun
drives a piston with a fuel-air explosion, and the piston compresses
and heats the hydrogen until it ruptures a burst diaphragm, after
which the hydrogen is free to push on the projectile.  For our gun,
which would have been considerably larger, the sizes and pressures
involved would have made the chamber impractical because of size.

We chose an alternate approach that has been tested on a small scale.
What you do is run the hydrogen through a particle bed of refractory
particles that have been pre-heated.  The hydrogen comes out hot
and runs into the barrel.  We chose aluminum oxide in the form
of particles used in #40 grit sandpaper.  It's fairly cheap and
available in large quantities.

Hydrogen is used in high speed guns because the guns are difficult
to make operate above the speed of sound of the working fluid (one
way to see this is if the projectile exceeds the speed of suond
of the gas, pressure waves can't keep up, so the gas stops exerting
pressure on the projectile.  That's a crude simplification, but it
gets the idea across).  Lighter atomic weight and higher temperature
mean higher speed of sound, so hot hydrogen is the best working

Dani Eder

From: (Dani Eder)
Subject: Re: Space Gun in Jan. Smithsonian
Date: Jan 17 1996
Newsgroups:,, (Jim Kingdon) writes:

>> An operational system that delivered propellants for GEO satellite
>> delivery was estimated at $70 million for the gun part.

>Well, OK, that is well less than billions (thanks for providing some
>data), but there is still the non-gun part to worry about (that is,
>somehow all that propellant needs to get into the satellite).

Total project cost, including a 'gas station' in LEO, a refuelable
upper stage, and the gas gun and the projectiles it fires was
estimated at $300 million in development.  Operations cost was
estimated at $600/kg of propellant delivered to LEO.

>> The satellite owner could launch the satellite itself for 1/4 the
>> launch cost

>???.  You mean Delta II instead of Atlas IIAS?  That is $50 million
>vs. $115 million, which is 43% not 25%.  If you mean payloads now
>going on Titan IV, sure, but that is a very small market.

A Delta II has something like 11,000 lb to LEO capacity.  The comsat
we sized the system for weighs 6,000 lb, so you need a bit more than
half a Delta II (either use a Titan II, a smaller Delta, or double
up on payloads on the Delta.

>Well, the question is how small?  Unless I see a lot more about how
>the propellant gets delivered I'm not so sure how small these costs
>could be.

The projectiles are launched from the gas gun at about 5 km/s.  They
use part of their propellant to get up to orbital velocity.  They use
on-board GPS to navigate to the vicinity of the 'gas station'.  The
'gas station' does the final rendezvous with the projectile.  The
projectile pumps most of the remaining propellant over to the 'gas
station' tank, then separates and uses the last bit of fuel to de-orbit.
It re-enters and hits the ground, and is then picked up and re-used.
The projectile has an ablative heat shield on the front, backed up
by 4 inches of crushable honeycomb.  The crushable stuff cushions
ground impact so the rest of the projectile is not damaged, even if
it lands on solid rock.  No parachute is required.  You can do this
because the projectile was rugged enough to be fired from a gun in
the first place, so landing doesn't impose as hard a design problem.
Even so, we allowed a 1/2% loss rate for projectiles in our cost
estimate (after testing, during testing we allowed for 4 out of 10
projectiles lost, and during initial operations we had a higher loss
rate factored in until the bugs are worked out).

The upper stage that delivers the satellite to GTO is re-used also.
Most of the time it sits parked at LEO, receiving fuel from the
'gas station' tanks.  Sometime during this period, the comsat is
launched, and the 'gas station' rendezvous with the satellite and
puts it on the upper stage.  When the upper stage is full, it goes
off and does the injection to GTO.  After releasing the satellite,
the upper stage does a slow (two week) aerobrake to return to LEO.
Meanwhile the 'gas station' has been storing fuel in it's onboard tank
(1500 kg capacity) (upper stage is 6000 kg capacity).

>If the gun really is too cheap to meter, and the delicate stuff really
>is a small fraction of the total cargo, the delicate stuff will still
>be a big fraction of the total cost.  As long as it costs $15 million
>(Soyuz) or $25 million (half of a Delta II, assuming a Gemini capsule
>for it was free), or $60 million (or your favorite shuttle cost number
>divided by seven), to get a human being to orbit, the access to space
>problem cannot be considered solved.

Ah, but one of the things you launch with your gun is cable to build
an orbital skyhook.  Not a full GEO version, but one that can knock
1-2 km/s off the launch vehicle job.  Now a fully reuseable SSTO can
have a decent payload fraction, say 10% rather than 1.5%, and thus
in a size big enough to carry a crew of 2 to orbit (5000 lb payload),
can be built with a 50,000 lb takeoff weight.  Compared to the 20,000
lb payload Delta Clipper, which weighs 1.3 million lb on takeoff, your
people carrier development cost should be 8.5% as much, or in the
hundreds of millions rather than billions.  Your people carrier can
also carry the comsats themselves, and other delicate cargo.  We looked
at an initial setup with the gun, the 'gas station', and the upper
stage, delivering 6 satellites a year to GEO to see if it made 
buisness sense (it did).  The upgrade to supporting an SSTO vehicle
was not analysed in depth, but it makes sense as an upgrade.

Dani Eder

From: (Dani Eder)
Subject: Re: Space Gun in Jan. Smithsonian
Date: Jan 17 1996
Newsgroups:,, (Filip De Vos) writes:

>Dani Eder ( wrote:

>Does the 1/6 massratio include maneuvering fuel and tracking/docking 
>hardware? Another problem could be the space junk thus generated. 
>Perhaps yet another contingency must be build in to dock the empty 
>containers together or to deorbit them.

The projectiles de-orbit after unloading fuel, so they can be re-used,
so they don't add to the orbital debris problem unless something goes
wrong.  The projectile initially carries fuel to get to orbit after
firing from the gun, fuel to unload, and fuel to de-orbit and return to
earth.  100 kg is the amount unloaded.  All the propellant is in one
set of tanks for structural economy.

>: As far as access to space, most of what you need in orbit (structural
>: materials, propellants, air, food) can be launched via gun.  A few
>: things, like people, computers, and delicate science instruments, need
>: to be launched more gently, but they represent a small fraction of the
>: total cargo.

>This requires that the components be put together by a sufficiently 
>intelligent assembly system = human in Space suit.

Yup.  If you are in the space construction business, the kinds of 
stuff you would launch first are a stockpile of oxygen and food in
100 kg lots, then launch some humans.  Thereafter you deliver more
food and oxygen to keep up your stockpile.

Dani Eder

From: (Dani Eder)
Subject: Re: Lunar Gun
Date: Jan 24 1996
Newsgroups:,, (Bill Arnett) writes:

>I've always thought the trouble with gun launchers is that the projectile
>has to be moving at orbital speed (or more) when it leaves the end of the
>gun.  But something going at 5 km/sec in the lower atmosphere is going to
>be subjected to huge aerodymanic resistance.  How did your proposal deal
>with this?

There were several things that had to be considered about the projectile
coming out of the gun.  Aerodynamic drag causes you to lose some of the
speed you had coming out of the gun.  I would have to look up what the
estimate was for the gun we studied, but it definitely was factored into
the performance calculation.  Moving at those speeds generates very
high aerodynamic heating.  This can be managed by ablative heat shields.
By comparison, the Galileo probe hd to dissipate a lot more heating.
The heat shield is partly consumed on the way up, and partly consumed
in re-entry later.  The heat shield and the crushable honeycomb behind
it that cushions the ground impact are the only parts that are designed
to be thrown away each flight.  Most of the projectile gets re-used.
You have to keep air out of the barrel but let the projectile out.
Finally the projectile makes a really big noise when it hits the air.
We had to define a 'keep out' zone to protect hearing, and there was
a 'kill zone' around the muzzle where even plants get killed by the
shock wave.  But then, artillery have always been noisy.

Dani Eder

From: (Dani Eder)
Subject: Re: SHARP "space gun"
Date: Mar 22 1996
Newsgroups: (Brian Hill) writes:

>I read an article in Smithsonian Magazine about two scientists from
>Lawrence Livermore National Laboratory who are testing a prototype space
>access launcher that operates a lot like a gun.  They believe that the
>initial full-scale launcher would cost $1.5 billion and that it could put
>objects into space for less than $600 per pound. That would appear to be
>about 10 times cheaper than current rockets. Their names are Hunter and
>Cartland and they are currently firing supersonic scramjets from their
>facility south of San Francisco.  The project is called SHARP for Super
>High Altitude Research Project.

>Does anyone know more about this project, or have email addresses for the
>investigators or web addresses regarding the project?

I was working on an in-house study of using a larger gas-gun as a
propellant delivery system, so I got to talk to John Hunter quite a
bit and even visited his gun.  I have some of their study and design
data, so ask away if you have questions.

Quick summary: the SHARP gun is designed to fire 5kg at 4 km/s,
with other masses at other speeds varying inversely.  It has a
big chamber (300 ft long x 12 in diameter) in which you detonate
a fuel/air mix.  This pushes a 1 ton piston, ahead of which is
hydrogen gas, which is compressed and heated.  When you reach
a set pressure, a rupture disk bursts, allowing the hydrogen into
the barrel (150 ft long x 4 in diameter) and off goes the projectile.

Last I saw, the SHARP gun fires into a bunker in a hillside, so you
have a couple of hundred ft of free flight before whatever you fire
destroys itself.  They can't fire into the air, because the projectile
would land way outside the Livermore property (like Nevada).  They
had hoped to get a few million dollars to move the gun to Vandenberg
AFB, where they could fire over the ocean and get longer flight
times for test projectiles.

Since the hydrogen gas follows the projectile out the barrel,and
it is very hot, it immediately burns, which makes a very 
impressive muzzle flash (100 ft flame).

The gun we studied (I was the study lead) would have had a
larger bore (60 cm), and fired 600 kg projectiles at 5.6 km/s.
It would have delivered 100 kg at a time of net cargo.  Instead
of a fuel-air explosion as a driver (which requires a chamber
much bigger than the barrel), we chose a heat-exchanger instead.

You have tanks of room-temperature hydrogen gas, which you
feed through a bed of heated aluminum oxide particles (otherwise
known as 40 grit sandpaper grains), which produces the hot
hydrogen gas you want as a working fluid.

You want hot hydrogen as a working fluid because gas gun efficiency
goes all to hell as you get to about Mach 1 of your fluid, and
hydrogen being a low moecular weight gas, and making it hot both
raise the speed of sound.

Dani Eder

From: (Dani Eder)
Subject: Re: Cannon Launch? (Very cheap access to space)
Date: Jul 15 1996

"A. Higgins" <> writes:

>The light gas gun concept cannot realistically be scaled up to the size
>necessary to launch a reasonable projectile (1000 kg) to orbital-class
>velocities.  Hunter has now acknowledged this and is proposing to invoke
>alternative technologies, such has particle bed heaters, to generate
>the hot hydrogen propellant.

I should like to point out a couple of things.  First, a particle bed
heated gas gun is still a light gas gun because it still uses hydrogen
gas.  I assume that when you say it cannot be scaled up, you are 
referring to the two stage gas gun, where a piston is driven by an
explosion and compresses and heats the hydrogen.  Such explosive driven
guns as have been built (the SHARP and delco guns being large
examples) push the limits of manufacturing capability for the
high pressure sections.

Second, we (Myself as study lead, Boeing Defense & Space Group as
funding source and owner of the data), did an extensive study of
a large gas gun for delivering propellant to orbit, with a particle
bed heated gs flow and a 600 kg projectile going to 5.4 km/s muzzle
velocity.  Our work was presented to Hunter in 1992, when he was
still in the thick of getting the SHARP gun operational.

We looked at not just the gun, but the overall system including the
launch site, projectile design & recovery, etc.  At the time we
concluded that going from the SHARP gun (5kg @ 4 km/s) to our 
concept (600kg @ 5.4 km/s) was too big a jump in size to take at
once, and that at least one intermediate size gun needed to be
built before the technical risk was low enough to consider the
big gun.

For general information, a particle bed heater is a container of
some high temperature refractory granules that are pre-heated.
When you are ready to fire the gun, room temperature hydrogen
is allowed to flow through the container, gets heated, then goes
to the gun barrel.  Using small particles gets you large surface
area, and thus high heat transfer rates.

For our study, we ended up choosing #40 grit aluminum oxide as
the particles.  This is the same stuff as you find on coarse
sandpaper.  It can stand high temperatures, and is available in
railroad boxcar quantities at low cost.

Dani Eder

From: (Dani Eder)
Subject: Re: Big gun
Date: Nov 01 1996

"D.J.Catling" <> writes:

>It is my understanding that a Light Gas Gun is only capable of
>accelerating rather small projectiles for the investigation of impacts
>into various materials.

Small guns can accelerate small projectiles.  Large guns can 
accelerate large projectiles.  The largest gun of this type
at present can shoot 5 kg at 4 km/s.

There is no particular reason that larger guns could not be built.

>For the people (person) who brought up the g problem, projectiles in a
>Light Gas Gun experience millions, even 10's of millions of g.  As far as
>I'm aware nothing short of solid particles can survive this.  There is
>also the question of the particle melting from the very rapid increase in
>it's energy.

That's way too high a g figure.  The highest pressure I know of in
a light gas gun is about 10,000 atmospheres, or 1 GPa.  This 
particular gun (the large one at Redstone Arsenal, Huntsville, AL)
fires projectiles 10 cm in diameter massing about 0.5 kg.  The pressure
on the projectile base is then 7.8 MegaNewtons, which produces about
1.5 million g's (for a few feet, the barrel is 150 ft long).  Typical
projectiles are nosecone shapes surrounded by nylon sabot pieces to
give a fit in the barrel.

Large guns operate at lower g's because the projectiles get longer
(more kg per square cm of barrel cross section), and the operating
pressures get lower for big guns because you can't fabricate the
pressure sections of the gun big enough.  For example, the gun I
was the study lead for operated at 100 g's, and the SHARP gun at
Livermore (the largest gas gun around right now) operates at 50,000
g's.  But then, the gun I was studying had a projectile that massed
120 times as much.

Dani Eder

From: (Dani Eder)
Subject: Re: Space Gun in Jan. Smithsonian
Date: Jan 24 1996
Newsgroups:,, (Brant L. Sponberg) writes:
>assume that either the "shell" that is launched by the railgun has an
>independent means of arriving at its destination (like small motors that
>fire after orbital insertion with homing devices that zero in on a signal
>from the target platform or are guided manually by a teleoperator on the
>ground or in space) or is picked up robotically or manually by an orbital
>transfer vehicle of some sort.  Were these costs included in your study? 

The projectile carries a GPS receiver and uses that to navigate to the
near vicinity of the 'gas station'.  It uses on-board small thrusters
to do this.  The 'gas station' uses a camera and manipulator arm 
combination to do the last ~300 meters of rendezvous and pickup.  It is
less expensive to put that equipment on one platform rather than many 

>There are some major engineering hurdles to overcome if the transfer
>system is part of the railgun "shell" itself, and there are major costs in
>the development of an orbital transfer vehicle.  Were any funds allocated
>for the development of a comsat system that can eject empty "expendables"
>tanks and accept (either manually or robotically) a new tank?  I think
>that when all these costs are figured in, a small railgun's launch costs
>might begin to approach standard launch costs. 

The major structural element in the projectile is the propellant tank.
If the tank is strong enough to survive being launched out of a gas gun,
it is strong enough to hold several hundred psi internal pressure, and thus
pump propellant to it's on-board thrusters and later the 'gas station'
via gas pressure.  So propellant transfer consists of plugging the
projectile into a fluid transfer line, opening a valve on the 'gas
station' for a while, then disconnecting line.  The orbital transfer vehicle
is madeup of mostly off-the-shelf parts (we used the bus from the 
MX missile, the part that injects the 10 warheads onto different 
paths - it was maeuverable enough, accurate enough, and set up for
releasing payloads, and radiation hardened, so it can survive multiple
trips through the radiation belts).

I'm not sure what you mean by ejecting "expendables" tanks.  The transfer
vehicle accepts propellant through the 'gas station' to refill it, the
gas station tanks stay put, and the projectile tanks come back to earth
with the rest of the projectile and get re-used.  The 'gas station'
places the projectile overboard with the manipulator arm, then backs
away.  The projectile de-orbits with the last bit of fuel in the tanks,
gets picked up and re-used.

Dani Eder

Date: 5 Apr 93 17:35:23 GMT
From: Dani Eder <>
Subject: Guns for Space

Okay, lets get the record straight on the Livermore gas gun.  
The project manager is Dr. John Hunter, and he works for the
Laser group at Livermore.  What, you may ask, does gas guns
have to do with lasers? Nothing, really, but the gun is physically
located across the road from the Free Electron Laser building,
and the FEL building has a heavily shielded control room (thick walls)
from which the gun firings are controlled.  So I suspect that the
office he works for is an administrative convenience.

I visited Hunter at the beginning of Feb. and we toured the gun.
At the time I was working on gas gun R&D at Boeing, where I work,
but I am now doing other things (helping to save the space station),

The gun uses a methane-air mixture, which is burned in a chamber
about 200 ft long by 16 inch ID (i.e. it looks like a pipe).
The chamber holds a 1 ton piston which is propelled at several
hundred m/s down the chamber.  On the other side of the piston
is hudrogen gas, initially at room temperature and some tens
of atmospheres.

The piston compresses and heats the hydrogen ahead of it until
a stainless steel burst diaphragm ruptures, at around 50,000 psi.
The barrel of the gun is about 100 feet long and has a 4 inch
bore.  It is mounted at right angles to the chamber (i.e. they
intersect).  This was done so that in the future, the barrel
could be raised and the gun fired into the air without having to
move the larger and heavier chamber.  The projectile being used
in testing is a 5 kg cylinder of Lexan plastic, 4 in in diameter
and about 50 cm long.

All of the acceleration comes from the expansion of the hydrogen
gas from 50,000 psi downwards until the projectile leaves the
barrel.  The barrel is evacuated, and the end is sealed with a
sheet of plastic film (a little thicker than Saran wrap).  The
plastic is blown off by the small amount of residual air trapped
in the barrel ahead of the projectile.  

The gun is fired into a bunker filled with sandbags and plastic
water jugs.  In the early testing fragments of the plastic
projectile were found.  At the higher speeds in later testing,
the projectile vaporizes.

The testing is into a bunker because the Livermore test range is
about 3 miles across, and the projectile would go 100-200 km
if fired for maximum range.  The intent is to move the whole gun
to Vandenberg AFB after the testing is complete, where they can
fire into the Pacific Ocean, and use the tracking radar at VAFB
to follow the projectiles.

The design goal of the gun is to throw a 5 kg projectile at 4
km/s (half of orbital speed).  So far they have reached 2 km/s,
and the gun is currently down for repairs, as on the last test
they blew a seal and damaged some of the hardware (I think it
had to do with the methane-air more detonating than burning, but
I haven't had a chance to talk to Hunter directly on this).

There are people waiting to test scramjet components in this
gun by firing then out of the gun into the air (at Mach 12=
4 km/s), since the most you can get in wind tunnels is Mach 8.

This gun cost about 4 million to develop, and is basically
a proof-of-concept for a bigger gun capable of firing useful-
sized payloads into space.  This would require on the order of
100 kg projectiles, which deliver on the order of 20 kg
useful payload to orbit.

Dani Eder

Dani Eder/Meridian Investment Company/(205)464-2697(w)/232-7467(h)/
Rt.1, Box 188-2, Athens AL 35611/Location: 34deg 37' N 86deg 43' W +100m alt.

Date: 28 Dec 1993 22:16:02 GMT
From: Jordin Kare <>
Subject: LEO alternative (gas gun)

In article <2fplmj$> (Eric D
ahlstrom) writes:

>Experiments with a light gas gun were described by
>Louis Bertolini, John Hunter (LLNL), James Powell (BNL),
>and Derek Tidman (GD) in "SHARP, A First Step Towards a
>Full Sized Jules Verne Launcher".   They have built and
>fired a hydrogen gun with a 5 kg projectile to 1.8 km/s.

SHARP is good for considerably higher velocities with small
projectiles; roughly 5 km/s.  SHARP is currently being used
for lethality tests (for possible future theater ballistic missile
interceptors) and for scramjet tests (firing real hydrogen-fuelled
scramjets at Mach 8 or so...)

>A similar version of this gun could be used to propel
>a 4 kg projectile on a suborbital trajectory with an
>apogee of 400 km.  The projectile would experience
>something under 40,000 g in the 150 ft tube.

Actually, it would be the same gun, moved to Vandenberg or similar
site, with the barrel elevated at an appropriate angle.

>They also propose a large Jules Verne Launcher (JVL)
>to launch a 1.8 m diameter, 10 t vehicle at 9 km/s from
>a 3 km long launcher inclined at 30 deg (inside a mountain).
>The vehicle would experience 2000 g.  (No passengers, please.)
>...  A small
>rocket is required for the final 200 m/s at the 500 km apogee.

Unless John Hunter has radically changed his designs, he's always assumed
a comparatively large apogee motor.  To get down to 200 m/s for the
apogee motor would require a radical aerodynamic turn at the top of the
atmosphere to bend the trajectory by 30 degrees.  Generally, I've seen
John's plans including a 2-3 km/s kick motor.

>So they calculate 5 t of payload to 500 km circular LEO
>per shot.  They estimate $5 B for construction and 10 years
>of operation.  At less than 1 shot per day they get 1000 t to
>orbit per year at $500/kg.  They think they could run it
>at several launches per working day, dropping the cost
>into the $200/kg range.

I've also seen John's estimate of the cost of an orbital launcher
work its way slowly up from $500 million to $9 billion.  Inflation,
I guess :-)

>All of this seemed a lot more real at the Princeton
>conference when they showed the video of the SHARP
>gun firing!  One side effect is that the hydrogen gets
>vented out the muzzle, and then ...  well, it ignites.

It's even more impressive when the pump tube blows out, which happened
a while back....

>Of course, this work at the Lawrence Livermore
>National Laboratory is also always threatened with
>being canceled.  I hope many of these different
>transportation options can be developed while we
>search for lower cost access to space.
>- Eric
>* * +1 804-766-9635 *  ISU'91 USA  *
>* Lockheed Eng & Sci Co, 144 Research Drive, Hampton, VA 23666 *

Seriously, the SHARP gun is a remarkable development, and John Hunter's
success in getting it built and keeping it running in the current
funding environment is nothing short of miraculous.  However, take the
Jules Verne Launcher with an appropriate grain of salt, especially
as to cost estimates.  But that's true of _all_ new launch
technologies ... except the ones I'm proposing, of course! :-) :-)

        Jordin (There's No Such Thing as a Free Launch) Kare

Date: 29 Dec 1993 02:15:51 GMT
From: Jordin Kare <>
Subject: LEO alternative (gas gun)

In article <> (Paul Dietz) writes:
>In article <2fqb72$> (Jordin Kare) writes:
>>  ...To get down to 200 m/s for the
>>  apogee motor would require a radical aerodynamic turn at the top of the
>>  atmosphere to bend the trajectory by 30 degrees.  
>I don't know if a light gas gun could do it, but one could also fire
>projectiles into higher orbits (with larger launch velocity), do a
>small burn at apogee to raise the perigee, then aerobrake down to LEO

This kind of approach has been suggested by the U. Washington ram accelerator
group.  It does save on the apogee kick, and lets you launch at a higher 
angle (less air drag and aero heating) but it requires higher gun 
velocity and much more precise trajectory control if you do use
aerobraking (as I recall, the U.W. group was using all-rocket propulsion
to change orbits, but still had a small delta-V win with the high-apogee
launch).  Far as I know, that's not John Hunter's plan, but I could be 
wrong; I haven't seen his Verne Gun presentation in full for some time.

>BTW, what's the status of the work on ram accelerators?  Anything
>still being funded?
>	Paul F. Dietz

The army is busy building fairly large ram accelerators with an eye to
making hypervelocity cannons for tanks.  If I recall correctly, they
currently have a ~4" diameter accelerator running, but details escape me....
Anyway, they're funding the U.W. group, and progress is being made.

	Jordin Kare

Subject: Re: textbook/papers on gas gun theory
From: (Andrew Higgins)
Date: Thu, 27 Mar 1997 22:28:38 +0200

In article <>, "A. Morris"
<> wrote:

> Anyone know where to get engineering
> (undergrad or postgrad) level design
> information on gas gun design?
> Thanks seems to be my lot in life to answer gas gun questions in this
group, so here we go again:

I would highly recommend:

     Seigel,A.E., "The Theory of High Speed Guns" AGARDograph 91, May 1965.

This is the *definitive* monograph on hypervelocity guns and should be in
any good engineering library.  Do not worry about having a background in
gas dynamics; Seigel has wonderful appendices which develop the Riemann
invariants, the method of characteristics, etc.  A condensed form of the
monograph can be found in the more accessible book:

     Seigel, A.E., "Theory of High-Muzzle-Velocity Guns," in
     "Interior Ballistics of Guns" ed. H. Krier and M. Summerfield, Vol.
     66, AIAA Progress in Astronautics and Aeronautics, 1979, pp. 135-175.

You should be able to buy this from the AIAA:

If you are less interested in the theory of gas guns and more interested
in the hairy-knuckled engineering, good references are:

     Canning, T.N., Seiff, A., and James, C.S., eds., "Ballistic Range
     Technology," AGARDograph 138, August 1970.

or any of the proceedings of the Hypervelocity Techniques Symposiums or
the Hypervelocity Impact Symposiums, held in the early 60's (again, in any
good engineering library).  There have been few advances on the design of
gas guns since then, but the (few) new developments are reported in the
International Journal of Impact Engineering.  The real work done on high
speed guns these days is discussed at the Aeroballistic Range Association
meetings, but the proceedings of these meetings are members-only and are
not found in even the best engineering libraries.

A slightly less technical description of the limitations of gas guns
and gas guns with distributed injection can be found in:

     Gilreath, H.E., Fristrom, R.M, and Molder, S., "The
     Distributed-Injection Ballistic Launcher," Johns Hopkins APL
     Technical Digest, Vol. 9, No. 3, 1988, pp. 299-309.

This reference would be an excellent place to start.
     Andrew J. Higgins            Department of Mechanical Eng.
     Shock Wave Physics Group     McGill University    Montreal, Quebec

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