WEC launchers (was re: Catapulting stuff, etc.)
Russell Crook
Tune inspired techniques for sending stuff into space, such
as cannons, a.k.a. light gas guns :->) knocked loose a weird
thought - actually two - that I had.
Fist, Why do light gas guns push the projectile from behind,
rather than from the side? Before you think I'm completely
insane, here's the idea:
Instead of the projectile being flat on the back, put a
symmetric wedge on the back of the projectile, say 1:5 or
1:6 aspect ratio (i.e., it's several times longer than it
is wide), with the sharp edge aligned vertically. Now,
instead of whacking the projectile from behind with hot
hydrogen, do so from the side, timing the release as the
projectile passes by. If done symmetrically, you should
be able to accelerate the projectile to speeds considerably
*higher* than the speed of sound in the driving medium due
to the wedge trading force for velocity. (Call this the
pumpkinseed effect :->) You might even be able to use
conventional high explosives to generate the gas.
Why won't this work? Or will it? Or is it a true WEC
launcher (physics or materials impossibility)?
Second weird gas gun idea: instead of using a
rupture plate and a barrel, could one use a series
of rocket nozzles to accelerate the gas to supersonic
speeds and whack the projectile with the exhaust
as it goes by? Is it not possible to get enough force
to accelerate the projectile in the distance required?
Comments (even if laughter) welcome ...
--
Russell Crook
Not speaking officially for Sun (or anyone else, for that matter).
It is true that to err is human -
but it can be overdone. -- Unknown
Andrew Case
>
>Instead of the projectile being flat on the back, put a
>symmetric wedge on the back of the projectile, say 1:5 or
>1:6 aspect ratio (i.e., it's several times longer than it
>is wide), with the sharp edge aligned vertically. Now,
>instead of whacking the projectile from behind with hot
>hydrogen, do so from the side, timing the release as the
Something vaguely similar has been done, IIRC. Drawing from
my very poor memory - The Army Research Lab in Aberdeen, MD
had a multistage gun that used a light gas gun to fire a
projectile into a second stage barrel. The second stage consisted
of a barrel slightly larger than the projectile, filled with a
stoichiometric mixture of Hydrogen and Oxygen. The projectile
was supersonic in the mixture at entry. The front of the
projectile was the usual conical bullet shape and the back
was a vaguely conical solid of revolution rather like the 'spike'
on an aerospike engine. As the projectile passed into the
H2/O2 mixture, the shock waves meeting the barrel walls compressed
and heated the mixture to ingition, like in a diesel engine. The
resulting explosion impinging on the shaped tail of the projectile
accelerated it forwards.
I'm pretty sure the project was in operation in 1994-1995, but I
think it's since been shut down. The projectile velocities achieved
were, IIRC, very impressive (substantially above light gas gun alone).
The number 8 km/s sticks in my mind, but it may be quite wrong.
The device is called a ram accelerator. Digging around on the web I
found this:
http://students.washington.edu/~buckwadl/RAM/ram.html
Turns out 8km/s is right after all.
.....Andrew
--
Andrew Case |
ac...@plasma.umd.edu |
Institute for Plasma Research |
University of Maryland, College Park |
Doug Jones
>
> This discussion of gear etc. based catapults (and other Looney
> Tune inspired techniques for sending stuff into space, such
> as cannons, a.k.a. light gas guns :->) knocked loose a weird
> thought - actually two - that I had.
>
> Fist, Why do light gas guns push the projectile from behind,
> rather than from the side? Before you think I'm completely
> insane, here's the idea:
>
> Instead of the projectile being flat on the back, put a
> symmetric wedge on the back of the projectile, say 1:5 or
> 1:6 aspect ratio (i.e., it's several times longer than it
> is wide), with the sharp edge aligned vertically. Now,
> instead of whacking the projectile from behind with hot
> hydrogen, do so from the side, timing the release as the
> projectile passes by. If done symmetrically, you should
> be able to accelerate the projectile to speeds considerably
> *higher* than the speed of sound in the driving medium due
> to the wedge trading force for velocity. (Call this the
> pumpkinseed effect :->) You might even be able to use
> conventional high explosives to generate the gas.
> Why won't this work? Or will it? Or is it a true WEC
> launcher (physics or materials impossibility)?
It's been thought of- aim your search engine at "transverse gas gun" and
read on.
> Second weird gas gun idea: instead of using a
> rupture plate and a barrel, could one use a series
> of rocket nozzles to accelerate the gas to supersonic
> speeds and whack the projectile with the exhaust
> as it goes by? Is it not possible to get enough force
> to accelerate the projectile in the distance required?
Distributed-charge guns have been around since WWII, and there should be
a mention of this technique in Dani Eder's Canonical Space
Transportation Methods
http://www.geocities.com/danielravennest/CanonAtoC.htm
> Comments (even if laughter) welcome ...
Las plus la change, la plus la même chose.
--
Doug Jones, Rocket Plumber
http://www.xcor.com
Russell Crook
Doug Jones wrote:
>
> Russell Crook wrote:
<snip rear wedge and sideways gas blast>
>
> It's been thought of- aim your search engine at "transverse gas gun" and
> read on.
I also received an excellent analysis from Dr. Andrew Higgins,
who also pointed me at some other resources. Apparently the common
technical term for the wedge is "boat tail", not pumpkinseed :->
Short summary: the boat tail technique has promise, though it
is not clear if has been successfully tested.
>
> > Second weird gas gun idea: instead of using a
> > rupture plate and a barrel, could one use a series
> > of rocket nozzles to accelerate the gas to supersonic
> > speeds and whack the projectile with the exhaust
> > as it goes by? Is it not possible to get enough force
> > to accelerate the projectile in the distance required?
The analysis by Dr. Higgins addressed this as well.
Short summary: not as effective and much
more complex than standard gun construction.
>
> Distributed-charge guns have been around since WWII, and there should be
> a mention of this technique in Dani Eder's Canonical Space
> Transportation Methods
> http://www.geocities.com/danielravennest/CanonAtoC.htm
Apparently, this document is now missing sections D to F
which means that the propulsion concepts are gone.
(but some of the older versions still on the web
do mention these possibilities.)
>
> > Comments (even if laughter) welcome ...
>
> Las plus la change, la plus la même chose.
Cue Merry Go Round Broke Down... :-)
--
Russell Crook,
Not speaking officially for Sun (or anyone else, for that matter).
The experiments of Skinner and other operant researchers did far
more than teach us how to pull habits out of a rat.
-- Gideon Glass (ggla...@calvin.edu)
Azt28
>
>Second weird gas gun idea: instead of using a
>rupture plate and a barrel, could one use a series
>of rocket nozzles to accelerate the gas to supersonic
>speeds and whack the projectile with the exhaust
>as it goes by? Is it not possible to get enough force
>to accelerate the projectile in the distance required?
>
>Comments (even if laughter) welcome ...
>
What you gain in speed you are losing in presure. When the supersonic gas
slams into the rear of the shell, it would produce a shock wave and loss energy
as heat.
A possible supergun would be a magneto hydrodynamics converter in a gun
(turning its energy into electricity) and a rail gun using that electricity to
accelerate a payload at high speed.
A classical gun with advanced grain (such the ones tested by John Bull) gives
up to 3000 m/s, a single stage rocket is then sufficient to get to an orbit.
Yvan Bozzonetti.