Re: Tank Sizes

Popeyesays@aol.com wrote:

> monty@arcadia.turner.com writes:
> 
> << One area this has pushed things is the development of liquid 
> propellants for the main gun. Thus you'd have a projectile that was 
> inserted, close the breech, squirt a given volume or weight of
propellant > into the chamber and *BOOM*. This would make resupply a
bit odd in 
> that you'd  transfer half of your ammo load via hose rather than by
hand > through the turret hatch. The big issue is the volatile nature
of such a > propellant. 
>   >>
> 
> Seems to cry out for a binary system - where you have two liquids or 
> gases that are NOT volatile until mixed.

The main problem is to get them properly mixed when you want them to
be. If the mix isn't homogenous when you ignite it, you get rather
nasty variations in muzzle velocity (and through it accuracy, and - for
kinetic rounds - penetration). Lots of work is being done on this, but
very little real progress during the past several years that I've heard
of.

Leakage can be an issue, but as long as no mixed propellant leaks out
there's no serious problem - which means that you'd want to mix your
propellant as late as you possibly can (ie, in the gun chamber). Since
the current sliding breaches are very nearly *gas*proof at extreme
pressures (and the cases where they aren't tend to be regarded as
disasters, costing the tank crew their eyebrows at least and their
lives at worst), I don't think there'd be much of a problem with a
sliding breach for liquid propellants at low pressures. You'd need to
close the breach before you pour the propellant in, but that's not a
problem.

Removing residual propellant can be a problem, but it only becomes
serious if you fail to mix the binary propellant properly - if it is
correctly mixed, there won't be any energetic residues. Cooling the gun
chamber to stop residual *heat* from igniting the reaction too soon
could well be a bigger problem.

> The screw in breach at least allows for bagged propellant and no
casing. 

I was under the impression that the M109 and the Challenger both use
bagged propellants rather than cased, and the ones I climbed around in
last November were definitely equipped with sliding breaches rather
than screw ones <shrug> 

Regards,

Oerjan Ohlson
oerjan.ohlson@telia.com

"Life is like a sewer.
  What you get out of it, depends on what you put into it."
- Hen3ry