On Wed, Jul 8, 2015 at 12:20 AM, Ethan McKinney <ethan.mckinney@gmail.com> wrote:

I don't know why you're fixated on squeezebores :)

Because I can't imagine a railgun with rails that are only some 5x as long as a man is tall are capable of creating enough acceleration to matter, unless the ranges in question are VERY short.

Of course, said ranges might well be VERY short. The capital ship combats in the show seem to take place at ranges close enough that the combatants appear to be visible to one another using the Mark 1 Eyeball.

Squeezebores are counter-productive in space. The purpose of a squeezebore is to reduce aerodynamic drag by crushing the sealing flange around a high-density penetrator core. The reason for a high-density penetrator core is obvious--hit a smaller area with more mass at a higher velocity to improve armor penetration. However, in vaccuum there's no aerodynamic drag, so you might was well use an APCR round--armor piercing composite rigid. APCR is like squeezebore ammo that's not squeezed or ADPS with a non-discarding sabot. In space, there's no loss of penetration, range, accuracy, or anything else from keeping the sealing flange.

Wouldn't making the round relatively smaller make it that much harder to track?

Also, the Galactica's guns might be designed for use in atmosphere. The Ragnar Anchorage was located in the cloud tops of a gas giant, after all. If ranges are relatively short by Traveller standards (per my above), "space" combat might potentially take place inside at least a tenuous atmosphere.

The real problem with the squeezebore in space is that you're losing a lot of energy crushing the sealing flanges against the body of the penetrator. This takes both mechanical energy to deform the metal and greatly increases drag.

But you *want* to increase the slug's drag along the bore. This is what let's you build up a higher effective pressure against the shrinking-diameter slug as it travels. That increased pressure is what increases the muzzle velocity so markedly. To achieve the same muzzle velocity without squeezing, you would need a relatively much larger cannon bore and a consequently much larger round. Given finite ammo storage capacity, this translates into the ability to carry relatively fewer rounds.

Essentially, tapering the cannon bore lets you place the mass/volume you'd otherwise have to invest in larger rounds into an (effectively) infinitely reusable reinforced detonation chamber. While the mass of that detonation chamber is several times that of a non-tapered weapon, the increase is worth it, since rather than carrying tens of thousands of relatively-more-massive rounds you get to carry *millions* of relatively less-massive rounds.

Richard Aiken

"Never insult anyone by accident." Robert A. Heinlein

"A word to the wise ain't necessary -- it's the stupid ones that need the advice." - Bill Cosby

"We know a little about a lot of things; just enough to make us dangerous." Dean Winchester