Home Forums General Game Design AFVs at an angle (not sloped armour) Reply To: AFVs at an angle (not sloped armour)

John D Salt

Do any rules allow aiming at weaker flanks, even if it is at less than 45° with the position the target is in, does this affect gameplay speed and is the ’45° rule’ good enough?

I’m sure lots of us remember the “tank stick” from the “Battle!” rules by dear old Charles Grant. This was a protractor-like device that showed a -1 or -2 deduction from the strike value of the attacking gun if the obliquity exceeded 30° or 60°. Since he also used a rule that frontal armour was always one more, and rear armour one less, than side armour, this meant that there was never any point accepting the -2 penalty, and you had to be outside the target’s 120° frontal arc to get a more advantageous shot than attacking the frontal armour straight on.

Apart from that I do not recall any wargames rules making much of a fuss about the angle of strike, even though everyone will tell you that German tank drivers in the desert were trained to keep their AFVs angled to the expected direction of attack, and if you look at the “Kleeblatter” in documents like the Tigerfibel it is obvious that attacks from the front or rear quarter are less effective than those from right angles. One problem is that during the course of a game turn lasting perhaps a minute, perhaps more, a moving AFV might have presented a number of different possible angles to the same shooter.

The original blog says:

I haven’t done the maths for obvious reasons

It’s only a little trig. If we used the sin-squared rule suggested on the Wikipedia page you link to — or pick an exponent you like between 1 and 2 — it is easy enough to knock up a spreadsheet to calculate the effective armour thickness offered by front, side, or rear plates at, say, five degree intervals all around the tank. Obviously I have been unable to resist the temptation to do exactly this, so anyone who wants a copy can have one if they e-mail me at musketoonltd AT gmail DOT com. Taking the example of a tank with 30mm front and 20mm side armour, and using the sine-squared rule (which overstates the effects of angle) we find that at 40° off the front the effective armour thickness for a gun’s best attack is 48mm — quite a bonus on 30mm. Not until we get round to 60° is the apparent armour thickness thinner than a straight shot on the front plate, and only at 65° is it closer to the side than the front thickness. This suggests to me that, as in so many things, Charles Grant’s “Battle!” got it pretty much right, and likewise the 120° frontal arc used (for obvious reasons of hex-related geometric convenience) in many boardgames is quite reasonable.

The 45° rule is clearly preferable to constructing lines through opposite corners of an AFV; your point about the artificial advantage of short, stubby tanks is well taken. However I think I would prefer a 60° rule instead, to give a 120° frontal arc. 90° seems too little, and 180° seems too much. Alternatively, in order to show the shape of Kleeblatter and the relative advantage to the AFV of being attacked from quarter angles, you might divide the circle around the target AFV into octants, and have separate armour values for front, front quarter, side, rear quarter, and rear aspects.

All the best,