Gremlich Johns, on 26 January 2012 - 12:46 PM, said:
Aaaaaah! But what is the caliber equivalence of the AC/RAC-2/5, AC-10/20 projectiles? Is the 2 a 20mm round, the 5 a 25mm or 30mm? Those are all pretty fast munitions. A DU projectile from a 105mm equipped M-1 (early 1980s) travels in excess of 5,500 ft/sec. I dunno what the 120mm (current M-1A2 ammo) DU flies at. As contrast, I've also shot 152mm ammo from an M60A2 (1970s) that was really slow (both service HEAT, willy pete and Missile) - so slow you could almost step out of the way if you could see their tracer/exhaust. Bullet, unless they've been backed by some wicked propellant technology, are not as fast as you might think. Squeeze bore tech could get some speed, and that was peaked in WWII.
From
Tech Manual, pg. 207:
Quote
For what amounts to one of the most basic combat systems on the modern battlefield, autocannons (often abbreviated as ACs) are a broadly varied class of rapid-firing, auto-loading, heavy ballistic weaponry—gigantic machine guns, in other words. With calibers ranging from 30 to 90 millimeters at the lighter end, to as much as 203 millimeters or more at the heaviest, most autocannons deliver their damage by firing high-speed streams or bursts of high-explosive, armor-defeating shells through one or more barrels. While caliber and firing rate can vary greatly, four main classes have emerged over the centuries, setting the standards by which all other ACs are rated, based on their relative ballistic damage. At the lightest end is the AC/2 class, followed by the long-time standard AC/5, then the heavy punch of the AC/10 class, and finally the brutal, close-in AC/20.
Additionally, the description of Ultra ACs (
Tech Manual, pg. 208) states, "Even though they cannot use special munitions (
their own magazines are tailored to the high-speed firing modes, which can be dangerous or detrimental to most specialty ammo), these weapons remain popular for attack and assault units."
This would seem to indicate that ACs are magazine/clip-fed (like the L21A1 RARDEN autocannon or most assault rifles) rather than belt-fed.
So, lighter ACs (AC-2 and AC-5) range from ~30mm to ~90mm, while heavier ACs (AC-10 and AC-20) range from ~90mm to ~203+mm
(Bear in mind that damage per shell should/would be a function of the shell's kinetic energy, determined by KE = 0.5*m*v^2; a massive shell moving very slowly and a very small shell moving very quickly can actually have the same KE, and thus inflict the same amount of damage despite the difference in size).
ACs are grouped by "damage classes" (essentially DPS) rather than by caliber.
AC-2s produce approximately 2 units of damage per 10-second period (the length of 1 CBT turn), or approximately 0.2 units of damage per second, at very long ranges.
AC-5s produce approximately 5 units of damage per 10-second period, or approximately 0.5 units of damage per second, at long ranges.
AC-10s produce approximately 10 units of damage per 10-second period, or approximately 1.0 units of damage per second, at medium ranges.
AC-20s produce approximately 20 units of damage per 10-second period, or approximately 2.0 units of damage per second, at short ranges.
As such, an AC that fires five bursts of four 1-damage shells at 2.5-second intervals is an AC-20 (4 damage per salvo * 5 salvos per 10-second period = 20 damage per 10-second period), as is an AC that fires a single 20-damage shell every 10 seconds, as is an AC that fires a steady stream of 2-damage shells at a rate of one-per-second for 10 seconds - they all have the same average DPS of 2 units of damage per second or 20 units of damage per 10-second period, so all are technically "AC-20s" regardless of caliber.
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