Re: [OT]Stupid question about sloped armour

Brian Burger wrote:

> On Wed, 1 May 2002, Roger Books wrote:
> 
> 
>>This has been bothering me for awhile.  How does sloped armour gain
>>me anything?
>>
> 
> It's just geometry, AFAIK, in two ways.
> 
> 1. Rounds are more likely to bounce off upward, rather that 'stick'.
> 
> 2. (the more important one) If you've got a round coming in parallel
to
> the ground, it's got to go thru MORE of an angled plate to reach the
> squishy bits of the vehicle inside.
> 
> Say we have a 10cm sheet of armour - if it's perpendicular to the
round's
> path, the round only has to go thru 10cm.
> 
> Tip the armour back a bit - or a lot - and your round has to go
through
> more actual thickness of armour on it's parallel-to-the-ground impact
> path. Slope the armour back 45 degrees and your 10cm armour is
effectively
> 12-14cm thick or so, without adding anything to the weight of your
> vehicle.
> 
> 
>>If I take the same mass of sloped armour and make armour perpendicular
>>to the ground I gain the same thickness you would gain from the
>>slope.  Space would remain the same (If I pivot the slope about
>>the center everything I lose from the bottom reappears on the
>>top.)
>>
> 
> Nope, you're just reduced the *effective* thickness of your armour by
the
> percentage (roughly) that it used to be sloped. Do a bit of scribbling
on
> scrap paper, and you'll see what I mean. Draw two parallel lines for
the
> inner & outer surfaces of your hypothetical armour plate, and then
measure
> lines passing thru at differing angles - non-perpendicular lines are
> naturally going to be longer, equalling 'thicker' armour when it's
sloped.
> 
> 
>>Where am I off? I'd think my reasoning would be obvious to
>>any engineer.
>>
> 
> I'm nothing even remotely resembling an engineer, and my math bites
too,
> but I think I've got the gist of it above.
> 
> Anyone who can give a better explanation - or correct me if I'm
totally
> off - please do!
> 
> Brian - yh728@victoria.tc.ca -
> - http://wind.prohosting.com/~warbard/games.html -
> 
> 
> 

There's a diagram on this page that illustrates the idea:

http://members.surfeu.fi/stefan.allen/strf9040.html

-- 
Ray Forsythe - erf2@gte.net - www.wombatzone.com