8,8 cm PzGr 39 Performance

[Peasant]

Yes, but because they have different muzzle velocities their starting Ballistic Coefficient would be slightly different.

That's news for me. I thought both weapons had muzzle velocity of 835m/s with 5cm PzGr.39, but you're saying they were different?

[Contender]

840 m/s (probably for HE).....5 cm Pzgr Patr 42: fuzed BD Z 5103, Projectile weight 2.34 kg (4.92lb), complete round weight 4.35kg (9.59lb). An armour-piercing shell of conventional design, this was made of chromium steel. The driving band was of soft Iron and the bursting charge was PETN/wax. A tracer, burning for 2sec, was also fitted. This round was issued as an anti-tank round for ground use, and was in fact the normal 5cm PAK projectile fitted to the flak case.

[Mobius]

Yes, but because they have different muzzle velocities their starting Ballistic Coefficient would be slightly different.

That's news for me. I thought both weapons had muzzle velocity of 835m/s with 5cm PzGr.39, but you're saying they were different?

You might have been confused 5.0cm KwK 38 L/42 is the early tank gun 685m/s. The PaK 38 is the anti-tank gun L/60 835 m/s.

[critical mass]

I have no information in regard to the KwK39, Flak 41 is positive, though.

[Mobius]

I have no information in regard to the KwK39, Flak 41 is positive, though.

You should have it. One 5cm KwK39 firing table can be found here.
http://www.lexpev.nl/manuals/germanyold.html
German WW2 aircraft ammo: Handbuch Für Flugzeug Bordmunition 1936-1945 [7482 KB] pg 62

[ThatZenoGuy]

So the KwK39 could fire PzGr42?

[Contender]

I suspect barring some workaround or complete abandonment or modification of the original Pzgr 39 round the optic would require a new "Pzgr 42" scale for accuracy due to the more aerodynamic shape. Anyone that has the Panzer III J1-M's T.z.f.5E or documentation relating to it can tell you one way or the other if there is a "Pzgr 42" scale unfortunately I have nothing on this other than the "simplification" (basic details are wrong- ) printed in the osprey books. The more recent Sdfkz-234/2 on the other hand used a T.z.f.4B optic as far as I know there is no description of this optic and I have never seen documentation or real life examples either.

[Mobius]

I suspect barring some workaround or complete abandonment or modification of the original Pzgr 39 round the optic would require a new "Pzgr 42" scale for accuracy due to the more aerodynamic shape. Anyone that has the Panzer III J1-M's T.z.f.5E or documentation relating to it can tell you one way or the other if there is a "Pzgr 42" scale unfortunately I have nothing on this other than the "simplification" (basic details are wrong- ) printed in the osprey books. The more recent Sdfkz-234/2 on the other hand used a T.z.f.4B optic as far as I know there is no description of this optic and I have never seen documentation or real life examples either.

There probably was some sort of jury-rigged workaround like was use for HEAT shells for 75mm guns. I think I remember
in the book 'Panzer Gunner' the gunner was suppose to do some math in their head to adjust the scale for certain shells. I don't think a new scale lens would be warranted for the sight.
But, we don't know if the PzGr 42 could be chambered in the KwK 39.

[Peasant]

I've analyzed these curves and assembled them into a spreadsheet that can be used to estimate the slope multipliers for german projectiles not just at fixed velocities but any in-between those shown in the original graph.



Link: https://docs.google.com/spreadsheets/d/ ... sp=sharing

[Peasant]

I've overlaid the charts for 6pdr AP and APCBC shells on top of each other and scaled them accordingly to highlight the differences. Might be interesting to see:

[Thoddy]

Both projectiles had a total weight of 6 pounds?
Whats the proportion of the AP-cap?

Result in general appears as correct, as the weight of the cap does not participate in the penetration process
except against very thin plates.

At high obliquity things changes a sufficent hard upper surface of the cap allows for biting into the plate and supresses the tendency being deflected towards plate.
See this
First sequence without cap
Second sequence small cap
Third sequence large cap
The deflection is reduced the larger the cap is

Screenshot_20220115-142650_Gallery.jpg

[Peasant]

Both projectiles had a total weight of 6 pounds?
Whats the proportion of the AP-cap?

Result in general appears as correct, as the weight of the cap does not participate in the penetration process
except against very thin plates.

At high obliquity things changes a sufficent hard upper surface of the cap allows for biting into the plate and supresses the tendency being deflected towards plate.
See this
First sequence without cap
Second sequence small cap
Third sequence large cap
The deflection is reduced the larger the cap is
Screenshot_20220115-142650_Gallery.jpg

Both 6pdr AP and APCBC have the same body, 2,86kg mass. The total weight of the APCBC shot is 3,23kg. So it's Cap + BC portion is a little smaller than in 7.5cm PzGr.39 (11,5% vs 12,9%).
Yet from this data "Report M.7000 A/11 No.1" it seems that the capped shot generally does not have an advantage over uncapped shot of the same body mass when attacking sloped targets, as the ballistic limits are (with a few outliers) very close.

[Contender]

Anyone that has the Panzer III J1-M's T.z.f.5E or documentation relating to it can tell you one way or the other if there is a "Pzgr 42"

Slight derail to earlier in the discussion in case anyone is interested I've recently come across the T.z.f 5E and it only features ranges for "Pzgr", "Spgr" and the machine gun, no Pzgr 40 (APCR) nor Pzgr 42.While the lack of Pzgr 42 was not really surprising what is curious is that the lack of Pzgr 40 which seemly supports the idea that only later (1943+) tank optics made any accommodation for Pzgr 40 ammunition.No luck on the T.z.f 4b and probably something best to give up on given its rarity.-

[Thoddy]

What shape had the ballistic cap of the 6 pdr.
Are hardness patterns of projectile and cap known?
Is this a 2 crh head?


With regard to performance of 6 pdr
https://forum.warthunder.com/index.php? ... erforming/

Most interesting
Ballistic equivalency sheet for different shells vs 240 bhn /460 Bhn armour plate

3-FB16780-857-E-4792-AA5-E-059-CD74-E6-A55.jpg

But I suspect its only valid for normal- ~30 angle of incidence.

[Timber]

Here is an interesting simulation of the 88mm.
https://www.youtube.com/watch?v=WVvA6TYXMLI

Some people use professional software like a toy. This simulation has nothing to do with reality and the creator has no basic knowledge in this area. If you want to find simulations that have something to do with reality, only here.

https://www.youtube.com/watch?v=76IBfPHFtUU

Don't see it as any more toy'ish than Djemian XYZ's videos tbh. Both creators are just plugging in figures to generate what'ever results they think look right.

Djemian has some pretty laughably unrealistic videos on 7.5 and 8.8cm PzGr.39 that are easily debunked by simple comparison with rl test results as well.