If the protection factor data is going to change for the new game, according to some new formula, then this is all moot I suppose. If the data are going to carry over as is, then would-be modders will be interested in figuring this stuff out.
I had relied on the rule of "divide by 15" -- as described in these forums by Capn Darwin -- for my 1962 scenarios that required some new tanks. So I was surprised to see this new formula in The Poor Man's Mod Guide 4. The new formula can be found on page nine.
To calculate a unit’s PF, use the following formula: ((Frontal Hull armor in mm/15) *0.3) + ((Frontal Turret armor thickness in mm/15) * 0.7) = PF
I am trying to create the U.S. M103 heavy tank which has hull armor of 130mm at the thickest point, and 250mm on the gun shield -- or mantlet. And the results I was getting with the two known formulas were less than I expected. And this led me down the rabbit hole of looking at the armor of some tanks in the spreadsheets that predate the various new technologies. Previously I had never had reason to examine those numbers.
The PF for the T34-85 in the Soviet user file is 7. I choose this example first because there has been plenty of opportunity to examine this model. Hull armor is widely quoted at 45mm, and turret armor at 90mm. So lets walk through this so people can correct my math if need be.
45/15 = 3. 3 * .3 = .9.
90/15 = 6. 6 * .7 = 4.2
4.2 + .9 = 5.1 PF
OK. Let's try sloping the hull armor at 60 degrees to give a line-of-sight thickness of 90mm.
90/15 = 6. 6 * .3 = 1.8
4.2 + 1.8 = 6
We could try dividing 90 by 15, but that just gets us to 6. But it gets us there faster than the longer formula. So lets try dividing 90 by 7. And we get 12.875.
Lets look at the T-55 and its 14 PF. Widely quoted sources use 100mm to 97mm for the front hull and 200mm to 203mm for the turret front. I'll use the thickest numbers.
For the published formula I get: 11.47
For the published formula modified by slope I get: 13.47
Divided by 15: If hull, then 6.66. If turret, then 13.53
And 203/14 equals 14.5
So let's look at the M60A series which are all rated at 18PF. And that makes their armor superior to the T55. At their thickest point, the front hulls are 143mm. The best information I have found on the turret for the A1 and A3 is 250MM adjusted for slope, as described by Hunnicut, A History of the American Main Battle Tank, 1984.
Published Formula: 14.52
Divided by 15: If hull, then 9.533. If turret, then 16.666
Or, 250/18 equals 13.888
And finally, the M48 with a PF of 14, which makes its armor rating equivalent to the T55. Here we have a hull at 110mm and a turret "equivalent" to 178mm per Hunnicut, Patton: A History of the American MBT, 1984.
Published Formula: 10.5
Divided by 15: If hull, then 7.33. If turret, then 11.86.
Or, 178/14 equals 12.71
So, after all that, my simple mind is left with several possibilities. The devs simply have access to better armor numbers than I do. But which formula should we be using?
Or if their armor numbers are roughly approximate to mine, and the data are correct, then the two formulas known to users are off.
Or, if one of the formulas is to be preferred over another, then the data are off, in some instances at least.
After typing all that, I sure hope I don't have to do the Emily Litella routine when the devs drop the simple explanation on my simple mind. But maybe I should do this stuff with my hearing aids on, just to be on the safe side.