Re: IAVRs

John Atkinson wrote:

> --- Tomb <kaladorn@fox.nstn.ca> wrote:
>
> > [Tomb] This is likely incorrect, or a bit of a red
> > herring at best. > I'm thinking that a weapon that
> fires projectiles > _much_ faster than
> > conventional rounds (in order to inflict good damage
> > using the old > KE=0.5MV^2 philosophy)would probably
> have barrel > wear issues, heating > issues, and if
> nothing else, battery issues (it > takes a lot of EMF
> > to sprint even a ferrous sliver up to "ludicrous
> > speed"). Also, with > more advanced built in systems
> for sighting, for > gyrostabilization, etc,
> > you may need other spares not currently required.
>
> Heh.	Mostly batteries--everything else would be
> trivial compared to batteries.  Although I still think
> that refraining from setting off explosions inside
> your weapon solves most of your heat problem.

The heat problem will be different, and you will still be setting off
explosives in the weapon.  Delivering the amount of energy to accelerate
a projectile to a high velocity requires very rapid discharge rates.
Let's plug some numbers in:

5g projectile
1m barrel length
600m/s muzzle velocity (~mach2)
180000m/s^2 average acceleration (V^2=2ad)
3.3 milliseconds to reach muzzle velocity
900j of muzzle energy

The average discharge rate during a shot is 270kilowatts.

The discharge rate looks impressive, but it is only a problem if the
weapon is firing at 300 rds/second (when it becomes the average power).
Only the muzzle energy is important.  The weapon's battery pack must
deliver the muzzle energy to firing circuits before the weapon will fire
a second time (we can assume that the firing circuits can hold one
charge).  What is an acceptable delay?	At a tenth of a second, the
battery pack must have a peak power of 9000 watts.  Unfortunately, we
have assumed that everything between the battery pack and the muzzle is
100% efficient.  This is seldom true.  So expecting the infantryman to
hump a butch enough battery for a few hundred shots is a bit much.  The
batteries will be expensive (due to discharge requirements), so
infantryman may have to lug it back to be recharged.

Explosively compressed coils can convert 25% of an explosive's energy to
electrical output (or they could in the late eighties [IEEE Spectrum
article on high powered microwave weaponry]).  A couple of D-cells will
now power the initiator for the ECC's (and hence the weapon), for
weeks.	The real advantage of ECC's is that if they include the
projectile in a combined cartridge (more likely side-by-side clips and
receiver), there is always a one-to-one correspondance between
projectiles and energy (prevents nasty surprises), so explosives will be