Armor thickness of a m4(76)'s turret?

[Lusche]

the book penetrations are at 30^o so it still looks reasonable, the thickness at 30^o is 100.46mm if ive got my trig right. the effective thickness will be even higher though.

Our M4(76) can penetrate 110mm at 1k and drops below 100mm just under 2k, which means it can penetrate the lower hull even at 30 degrees at those ranges (which is in turn in line with ingame tests).
But the Waffenpruefamt tests say: impossible at any range!

Penetration up to 2k vs no penetration even point blank... something doesn't add up.

I will look into some more sources, do some number crunching and may start a separate thread later today.

[RTHolmes]

yeah but the tested 2k penetration is straight on, the book values are at 30^o to the tank. what angle is the lower front hull (or what is the incident angle straight on)?


edit: I'd be interested to see some penetration/incident angle data for APCBC rounds, cant find any at the moment. (point being that the penetration isnt a direct relationship to cos(^o) )

edit2: that wasnt very clear, what I mean is that calculating the armour thickness the projectile sees at the incident angle gives you the LOS thickness. because of deflection effects, the effective thickness is much higher. and the higher the incident angle, the greater the difference between the LOS thickness and the effective thickness.

[Lusche]

yeah but the tested 2k penetration is straight on, the book values are at 30^o to the tank. what angle is the lower front hull (or what is the incident angle straight on)?


edit: I'd be interested to see some penetration/incident angle data for APCBC rounds, cant find any at the moment. (point being that the penetration isnt a direct relationship to cos(^o) )

edit2: that wasnt very clear, what I mean is that calculating the armour thickness the projectile sees at the incident angle gives you the LOS thickness. because of deflection effects, the effective thickness is much higher. and the higher the incident angle, the greater the difference between the LOS thickness and the effective thickness.

I have taken the effects of genuine slope as well as the additional side inclination of 30 degrees into account.

[RTHolmes]

sure, but simply using LOS thickness wont give you useful numbers to compare to the book penetrations at such a high incident angle. my 3D trig is very rusty, have you got the incident angle from 30^o?

[Butcher]

I don't want to jump to early conclusions, I'm just starting to form one.

But the discrepancy is astonishing. In game, the lower hull can easily be penetrated my the M1A1 76mm gun at ranges up to 2k. The numbers from the tests of the Waffenpruefamt in 1944, as cited by Jentz, say no pentration possible at any range (at 30 degrees).
While it is always a bit problematic to compare different tests, the is simply too fundamentally to be ignored.

In 1944 the Germans even reduced the lower hull armor thickness from 60mm to 50mm with the introduction of the G variant in order to increase armor at some other locations like rooftop or some parts of the side armor.  Certainly they would not had done that to a very critical location if that would have been seen as taking a high risk.

 

Yeah the tests I did were with Hooter (in case most don't know were a pair of tank wreckers), I asked him to the DA to run the battery of tests because I had a feeling something was off on the Panther being destroyed a little to quick from the front lower hull.

Here's my biggest problem - I will post a photo to better show what I am wondering about -



The Front Lower hull seems a bit to low to have a round fly and Arc then penetrate, I would assume it would hit the upper hull the majority of the time, however I am in Awe that in a battery of tests done, Hooter was able to hit that Front Lower hull 1 outa 5 tries at varied ranges.

Granted I am a good shot also, but i don't feel it should be hit that often, Sure it's possible to hit it, however I think the numbers are out of wack.

[Lusche]

sure, but simply using LOS thickness wont give you useful numbers to compare to the book penetrations at such a high incident angle. my 3D trig is very rusty, have you got the incident angle from 30^o?

I'm not sure i understand what point you are trying to brign across... maybe I'm a bit slow today. Ok, not just today

The basic problem:
The real world data as presented indicates there is no penetration possible of the lower hull at any range at 30 degrees. But in game there is! If you duplicate the setup, the rounds are easily penetrating lower hull even at long ranges. I'm doing it right now.

[Lusche]

The Front Lower hull seems a bit to low to have a round fly and Arc then penetrate,

The round doesn't arc as much as you seem to think. The AoI is at maybe 1-5 degrees only.

[RTHolmes]

AB is armour thickness
AC is LOS thickness
AD is effective thickness

the angle between AB/AC is the incidence
the angle between AD/AC is the deflection

[Butcher]

I'm not sure i understand what point you are trying to brign across... maybe I'm a bit slow today. Ok, not just today

The basic problem:
The real world data as presented indicates there is no penetration possible of the lower hull at any range at 30 degrees. But in game there is! If you duplicate the setup, the rounds are easily penetrating lower hull even at long ranges. I'm doing it right now.

I'm glad someone has found some data on this, it concerns me that real world data says there isn't any penetration at 30 degrees, but you clearly can see a Panther be penetrated at 2k (assuming you hit the front lower hull).

[RTHolmes]

but you clearly can see a Panther be penetrated at 2k (assuming you hit the front lower hull).

... at 30^o?

[Lusche]

(Image removed from quote.)

AB is armour thickness
AC is LOS thickness
AD is effective thickness

the angle between AB/AC is the incidence
the angle between AD/AC is the deflection

The point is? 

[Lusche]

... at 30^o?

I just pentrated it at ~30 degrees at 1.3k with my 3rd hit.

[Butcher]

I just pentrated it at ~30 degrees at 1.3k with my 3rd hit.

The Panther is broken!!!! Lusche has spoken!

[Lusche]

The Panther is broken!!!! Lusche has spoken!

whoa, don't be so quick! Nothing final yet.


One thing still to consider - what rounds had been used?

[RTHolmes]

The point is?  

comparing apples/oranges


ok 1.3k/30^o doesnt sound right.