From: Alan and Carmel Brain <aebrain@w...>
Date: Wed, 1 May 2002 16:52:33 +1000
Subject: Re: [OT]Not-Stupid question about sloped armour
> This has been bothering me for awhile. How does sloped armour gain > This has been bothering me for awhile. How does sloped armour gain As you surmised, Armour sloped at 60 degrees is effectively twice the thickness of armour at 0 degrees. ( Multiply raw thickness by 1/cos(Slope) ) Trouble is, you need twice as much to cover the same vertical area. So no gain, right? Except that almost no hits are exactly square-on. They're at about 15-20 degrees or more. So a slope of 0 degrees becomes an effective slope of 15-20 degrees. Not a huge gain (1.06). But a slope of 60 degrees becomes an effective slope of 70-75 degrees. And 75 degrees is about 4 times (3.86) as effective. There are complications - conventional solid shells tend to veer in the direction of greatest resistance when they hit armour, so the formula is at best an approximation. OTOH at really high angles, they'll bounce off. OTOH Plunging fire at long range will also decrease the effective slope. For really high velocities you can best think of the collision as a slug of fluid hitting a sheet of fluid, so the mechanics are different again etc etc. A reasonable rule of thumb would be to say that armour sloped at 60 degrees weighs twice as much, but is 3.5 times as effective, as the same thickness of armour sloped at zero. 100mm at 0 degrees protects *in the field* about as well