Hyper-velocity cannon.

[omg4]

From om...@aber.ac.uk (omg4)

Currently the USA and UK are jointly researching Hyper-velocity cannons.
These work by propelling a projectile by way of electricity rather than
by a chemical propellant. The main utility of this type of weapon is
intended for use by the army, since the standard design of cannon has
almost reached its maximum scientific potential (see AFJI), and the
potential power of rail or coil guns (hyper-velocity cannons, the
rail-gun concept being the type researched) being so great.
A naval utility has been envisaged also, for anti-missile defence,
since the extended range and penetration of a weapon which propells a
projectile at velocities of up to 6 km/sec (the maximum velocity possible
for a chemically propelled projectile is 2 km/sec) is ideal for defeating
incoming missiles. Hyper-velocity cannon technology still has a decade
or two of development before it sees operational use however.
A second piece of technology envisaged for the future is the High-speed
underwater missile. Speeds of up to 1000 kts have been envisaged for
this weapon (I personally see that speed as a little ambitious), to
generate the kinetic energy to achieve deep penetration of a vessel`s
hull.
My question is this: could a railgun propelling a 5-7 kg projectile at
6 km/sec be used to attack submerged targets such as torpedoes, or a
high-speed underwater missile (if the project comes to fruition), and if
so, how deeply would the projectile be effective to (this may be a
question more for physicists).

See back-issues of Navy International.
OWAIN M GOWER.

[Mike Stucka]

From mst...@orion.it.luc.edu (Mike Stucka)

omg4 (om...@aber.ac.uk) wrote:
: My question is this: could a railgun propelling a 5-7 kg projectile at

: 6 km/sec be used to attack submerged targets such as torpedoes, or a
: high-speed underwater missile (if the project comes to fruition), and if
: so, how deeply would the projectile be effective to (this may be a
: question more for physicists).

My understanding is that current railguns launch projectiles that weigh
no where near what you are describing; are several hundred feet long; and
use more electricity than you can shake a stick at. Even assuming that
incredible leaps and bounds could be found in this technology, you'd be
trying to track a fairly quiet target (the torpedo) in a ship's (noisy)
wake with quite literally pinpoint accuracy. Then you'd need to bring to
bear the presumably still-bulky railgun. In other words, no. :)

I'd be very curious to see how they propose such quick underwater
missiles given that the resistance of water is far greater than that of
air. For the missile to contain enough anaerobic propellant, you'd have
to be looking at an extremelly narrow (to reduce resistance) missile that
is extremely long. In other words, no. :)

I always wondered if the Navy might consider deploying some sort of
floating charges to deploy in the wake of the ship in close proximity to
the torpedo, either to damage to the sonar or get a sympathetic explosion
off the warhead.

___
"Democracy means freedom of sexual choice between any two consenting
adults; Utopia means freedom of choice between three or more consenting
adults." -- Johnny Carson
Mike / mst...@orion.it.luc.edu

[Trip]

From tr...@cco.caltech.edu (Trip)

mst...@orion.it.luc.edu (Mike Stucka) writes:

>omg4 (om...@aber.ac.uk) wrote:
>: My question is this: could a railgun propelling a 5-7 kg projectile at
>: 6 km/sec be used to attack submerged targets such as torpedoes, or a
>: high-speed underwater missile (if the project comes to fruition), and if
>: so, how deeply would the projectile be effective to (this may be a
>: question more for physicists).

>My understanding is that current railguns launch projectiles that weigh
>no where near what you are describing; are several hundred feet long; and
>use more electricity than you can shake a stick at.

It's not *that* bad. As of a couple of years ago, a coilgun about two
meters long and weighing a few hundred kilos could produce 3.84MJ of
muzzle energy (about 40% of what a 120mm tank gun puts out).
Unfortunately, I have lost all the specs I wrote down except the energy,
but I think the muzzle velocity was about 2km/s, so the projectile would
have been 1-2 kilos. It did need about 10-12MJ of energy, though, which
works out to a ton or so of homopolar generator, plus a standard
generator to charge *that* up.

But the idea of an underwater coilgun does seem pretty silly. Drag goes
as the square of velocity, so hypervelocity projectiles lose energy even
more rapidly than slower rounds, which already don't carry any
appreciable distance through water.

Trip
--
"Language, n. The music with which we charm the serpents guarding
another's treasure." -- St Bierce