It all started rather simple, going over Bushmaster 30mm Mk44 AC statistics and I had 3 references that said "over 100 mm @ 1000m 0deg." I also encountered 40mm BM and Bofors stats including muzzle velocity, travel time etc. and being what I am (computational science minor), I started digging in. So all the physics aside, I made a simplistic assumption that gravity doesn't matter to vertical speed (it does, but not much at these speeds/ranges) and came up with some fancy equations without an exact solution. Unanswered questions remained, like "is the armor penetration depending more on the momentum (velocity x mass) or the kinetic energy (½ x mass x velocity x velocity)?"
After 5 a4 papers with equations and some coding, here's the php scripts that I made:
First:
round velocity and distance (plus penetration capability as percentage of point blank range both for momentum and energy) by time, given the muzzle velocity and drag constant*) for type of ammo:
http://www.venhola.com/winspmbt/sabotcalc.php
Second:
Estimate the drag constant for ammo given the muzzle velocity and flight time to distance:
http://www.venhola.com/winspmbt/sabotcalc2.php
You can use the second to estimate the value for the first and to get penetration estimates at given flight times. Unfortunately not yet for distances.
What I suspected was that the penetration capability is dependent both on the momentum (which dictates the impact peak force) and energy (which is reduced on impact due to changing form of armor) and at least for Bushmaster 30mm Mk44 AC it was almost 100% match using 50:50 division between them, so I added the 50:50 mix to the lot. I was using
this data as a reference as it reflected pretty much the penetration in OOBs for 30mm BM Mk44 (120 mm @ 0m 0deg vs. approx 62 mm @ 0m 60deg).
As an example, 40mm Bofors AC - used in Swedish CV9040 - has been given table values "Muzzle v: 1.48 km/s flight time to 1.5 km = 1.1 s". The 2nd link gives us a constant c = -0.10773241083846 (last iteration result) which we feed to first. As a result for flight time 1.1s it gives:
t: 1.10s v: 1.26 km/s dist: 1.50 km momentum: 85.1% energy: 72.4 % combined: 78.7%
Suggestion there is that penetration at 1500m should be 78.7% of 0m penetration 200mm, 200 x .787 = 157.4 mm
Army-guide.com tells us "At a tactical firing range the penetrator can penetrate armor well in excess of 150 mm."
"When firing against armoured vehicles the maximum upper range bracket is between 1500 and 2000m" (The Bofors Gun, Terry Gander)
at 2km it is 72.9% or 146mm, which is again well within scope.
The problem with sabot ammo is naturally that after given range the accuracy and efficacy drops, but is the sabot range in OOBs there to keep the game balanced (sacrifice some penetration value realism for tactical realism = "don't be trigger happy @ 3km ranges") or is the sabot ranges for modern autocannons close to gun max ranges because they just used to be about the same for MBT guns? Judging from
this pic the 30mm Bushmaster should have Sabot Range set somewhere 150 hexes...
*) drag constant here is in physics POV "½ x density of air x cross-surface area x C", where C is between 0 and 1 and depends on the form of the object. However, one number is enough for us.
Sabot range for modern autocannons
Threaded Mode