US Armour Basis Curve

Discussions on all aspects of the United States of America during the Inter-War era and Second World War. Hosted by Carl Schwamberger.
Peasant
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US Armour Basis Curve

Post by Peasant » 20 Apr 2020 15:21

I've reverse-engineered the mathematical function used to plot this curve inside the 30° to 60° interval:

Image

Here is the table:

Image

Example: Finding the thickness quotient for a plate at 53° obliquity:

Image

Peasant
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Re: US Armour Basis Curve

Post by Peasant » 20 Apr 2020 16:26

For curiosity, assuming that the curved mantlet of the turret of M26 tank is designed to have the same 7" armour basis as its UFP, its armour profile would look like this:

Thickness(in.) Obliquity(°)
  • 5,5; 31,9
  • 5,0; 36,8
  • 4,5; 41,7
  • 4,0; 46,7
  • 3,5; 51,9
  • 3,0; 57,5
  • 2,5; 63,9 (extrapolated)

Carl Schwamberger
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Re: US Armour Basis Curve

Post by Carl Schwamberger » 28 May 2020 02:20

I'm not a armor geek. How would one use this calculation?

Peasant
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Re: US Armour Basis Curve

Post by Peasant » 04 Jul 2020 11:14

Carl Schwamberger wrote:
28 May 2020 02:20
I'm not a armor geek. How would one use this calculation?
Sorry for taking so long to answer. Next time quote in your post my post (no need to quote the entire post, just the "quote="Carl Schwamberger" post_id=2271175 time=1590628843 user_id=20612" part will do, so that the forum will notify me that there is a new message in the thread.

This table allows one to convert between a given thickness of armour set an an angle and a thickness of a vertical plate required to give the equivalent protection. Its designed to work best with US APC projectiles against US rolled homogeneous armour.

For example, lets take the early Sherman tank's upper front plate of 2in. at 56° and multiply that thickness by the relative coefficient from the table, which would be about 2,24. This gives us the equivalent of (50,8mm) * 2,24 = 113,8mm of vertical armour, or almost exactly 4.5in. same thickness as the vertical portion of the late version cast final drive armour.

I want to stress again that this value is accurate only for WW2 period US APC projectiles, the equivalent armour protection could be higher/lower against other types of AP projectiles(sharp tipped AP w/o cap, soviet blunt headed AP, sabcaliber projectiles ecc) and even the APC projectiles(supposed to be nominally the same) of other nations of the period and of the post-war era.
Last edited by Peasant on 04 Jul 2020 17:55, edited 1 time in total.

Carl Schwamberger
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Re: US Armour Basis Curve

Post by Carl Schwamberger » 04 Jul 2020 17:12

Thanks



When I start a thread I usually active the replay alert. Any posts trigger a msg to me.

Peasant
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Posts: 336
Joined: 16 Oct 2018 17:21
Location: Italy

Re: US Armour Basis Curve

Post by Peasant » 04 Jul 2020 18:00

Carl Schwamberger wrote:
04 Jul 2020 17:12
Thanks

When I start a thread I usually active the replay alert. Any posts trigger a msg to me.
Usually I do it too, but it seems I forgot this time. There seems to be a setting in the board options that does this automatically for you, I've enabled it, hope it works from now on.

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