Effective thickness of hemispherical cheeks on Soviet tanks

[Peasant]

Inspired by this thread: http://community.battlefront.com/topic/ ... ulnerable/

Many sources on technical data on WW2 tanks limit themselves to specifying only the nominal thickness and noting "curved" besides. I wanted to see for myself how well these numbers describe the actual protection provided and I've made this drawing of the proportional sectioning of a hemisphere to study the angles presented from the front by this design.



As you can see, only less than 25% of total area presents an angle less than 30° and >50% over 45°, so the median value of effective thickness would be that of the vertical part angled at 45°, which would be about x1,75 - 2,00 times that value, for AP/APC projectiles.

Well, there you go. Let's begin the discussion.

[Carl Schwamberger]

I wonder if the French were looking at this in the 1930s. A lot of curves & acute angles on the new tank designs post 1935. Similarly the US Army was working curves & pronounced angles into turrets & hulls

[Peasant]

I've been looking at the schematics of JS-1 turret and thinking how misleading the figure of "100mm" is. It implies that the protection level was similar to a flat 100mm plate. In actuality a large portion of area presented from the front is made up of extremely sloped sides, presenting a target impenetrable to any WW2 era anti-tank guns.
At 30° side angle, it's not as impressive but still most of the area presented has 100mm/30-40°.