Curved Mantlets. How are they calculated.

[chuckfourth]

Hi All
While looking at the LVT armour values I noticed that the mantlet for the lvt(A) 4 (unit 022) has a value of 6 for Turret Front but its Mantlet is only 38 mm thick, so I guess that as the mantlet is curved (0-60 degrees) then this explains the 33 % increase in armour value. This is the same turret/mantlet as mounted on the M8, units 011, 117 and 343 in the marines, and units 019 and 191 in the US Army. I then checked this against the Panther mantlet which is 100mm thick and has a Turret Front armour value of 12 (16 percent increase), so I guess having a curved mantlet means we add two to the armour value the mantlet would have had if it was flat. However this doesnt seem to always be the case if we look at panzer III, using data largely from http://afvdb.50megs.com/germany/

Unit___Tank_____________curve degrees______thickness mm__________current in-game armour value
_______M8_______________0-60________________38_____________________6
_______Panther__________0-90_______________100____________________12


352____PzKw IIIa/d__________________________15(can be 30 for d)_______2
404____PzKw IIIb/d (s)______________________15(can be 30 for d)________3
007____PzKw IIIe-3.7cm__Round_______________30_____________________ 4
279____PzKw IIIe______Round_____________________30____________ _____4
579____PzKw IIIe-5cm_______________________________________________ 4
008____PzKw IIIf-5cm____Round_______________30_____________________ 4
389____PzKw IIIf________Round_______________30________________ _____4
583____PzKw IIIf-3.7cm_____________________________________________ 4
009____PzKw IIIg-5cm____0-45________________37_____________________4
584____PzKw IIIg-3.7cm_____________________________________________ 4
010____PzKw IIIh________0-45________________37_____________________5
940____PzKw IIIh________0-45________________37_____________________5
011____PzKw IIIj________0-45________________50_____________________5
012____PzKw IIIj/1______0-45________________50_____________________5
850____PzKw IIIj________0-45________________50_____________________5
851____PzKw IIIj/1______0-45________________50_____________________5
941____PzKw IIIj________0-45________________50_____________________5
942____PzKw IIIj/1______0-45________________50_____________________5
013____PzKw IIIL________0-45________________50 + 20________________5
430____PzKw IIIL________0-45________________50 + 20________________5
014____PzKw IIIm________0-45________________50 + 20________________7
278____PzKw IIIm________0-45________________50 + 20________________7
397____PzKw IIIm________0-45________________50 + 20________________7
431____PzKw IIIm________0-45________________50 + 20________________7
943____PzKw IIIm________0-45________________50 + 20________________7
015____PzKw IIIn________0-45________________50_____________________6
277____PzKw IIIn________0-45________________50_____________________6
398____PzKw IIIn________0-45________________50_____________________7
432____PzKw IIIn________0-45________________50_____________________6
944____PzKw IIIn________0-45________________50_____________________7
016____Flammpanzer III_____________________________________________8
203____PzKw III Tauch_____________________________________________ _4
433____Flammpanzer III_____________________________________________8

Firstly I note that the same vehicle can have different values, IIIn has either a mantlet of 6 or 7, IIIg and IIIh both have 37mm mantlets but have values of 4 or 5.
Secondly in most cases for panzer III the fact that the mantlet is curved has been ignored when allocating Turret Front armour value.
Thirdly IIIL has had the extra 20mm of spaced armour on its Mantlet ignored when allocating Turret Front armour value.

If the rule is in fact "plus 2" for a curved mantlet then the turret front armour value for;
Unit 352 should be 4.
Unit 404 should probably be 5 assuming it has the 30mm mantlet.
Units 007, 279, 579, 008, 389 and 583 should be 5 not 4.
Units 009, 584, 010 and 940 should be 6 not 5 or 4.
Units 011, 012, 850, 851, 941 and 942 should be 7 not 5.
units 013, 430, 014, 278, 397, 431 and 943 should be 9 not 5 or 7.
Units 015, 277 and 432 should be 7 not 6
Units 398 and 944 are actually correct at 7!

008, 943 and 389 have the wrong picture.
Best Regards Chuck.

[halstein]

I think that what you add is determined by the angular functions (sine and cosine), and there migth also be some factor from steel-quality.
Halstein.

[mr_clark]

I don't think it will work as simple as adding "2".
Every tank has a differently curved turret, and every degree more or less actually changes the amount of armour a AP round has to pass through.

[chuckfourth]

Hi Halstein
Currently SPCAMO doesnt model armour quality, so that makes things a bit simpler, the formula Y/cos(Z)=X gives us some workable numbers.
working on a "test" 40mm thick turret and firing shells from straight ahead, we have these considerations. If the shell hits in the "middle" ie on the flat surface then no curve and armour protection is 4. If it hits on an upper or lower edge we have the maximum mantlet thickness.
using the pz 3's 0-45 degrees mantlet, an edge hit gives an"angle" thickness of 57, a 30% increase
using the m8's 0-60 degrees mantlet, an edge hit gives an "angle" thickness of 80, a 50% increase
using the panthers 0-90 degrees mantlet, well the formula doesnt really work here but its about a 160mm "angle" thickness (using a diagram), a 300% increase.
If you wanted to use these percentages then for say pz 3 g with a 37mm mantlet then an increase of 30% gives a maximum thickness of 49mm so maybe plus one in this case.
but for pz 3 m with a 70mm mantlet then an increase of 30% gives a maximum thickness of 93 so maybe plus two in this case.
Also to be considered is the fact that as you move away from the centre line of the mantlet the chance of the shell ricocheting increases which is probably the main advantage of the curve. How the chance of a ricochet increases with the increasing curve I dont know obviously it would be 100% at 90 % but at the halfway mark 45 degrees it is probably higher than 50 percent. And of course there is always the problem of the ricochet going through the hull roof but it has of course lost a lot of energy by bouncing.
Note I am not asking for panther front turret to be given a factor of 48. Personally Im happy with plus 2 or something similar for all curved mantlets. I just submit these numbers for interests sake.
Best Regards Chuck.

[chuckfourth]

Hi Mr Clark
I too would be very interested how SPCAMO calculates the effect of curved armour, mantlets in this case.
(Thinly veiled nag)
Best Chuck.

[DRG]

It involves chicken entrails and a full moon....

Don

[Tiger_Reyth]

LMAO

[Marek_Tucan]

DRG said:
It involves chicken entrails and a full moon....

Don

And ouija board and tank's voodo doll. And a bit of coffee, at least from my experience

[chuckfourth]

Hello
Seems to me that pz 3 tauch should have a TF value of 5 not 4 as it has a thickness of 3cm. pz 3 e with the same mantlet thickness gets a TF value of 5.
the earliest model of pz 3 converted to tauch is pz 3 d with mantlet thickness of 3cm.
Best Regards Chuck.