WWII Tank Gun Specifications

[dunmunro1]

Thanks for that info. The data posted by Soren also shows a much steeper decline in penetration for the L/70 gun versus the 17 pdr, and this is to be expected if the 17 pdr performs better at higher target angles:

7.5cm KwK42 L/70
2,500m = 103mm
3,000m = 91mm
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7.62cm 17pdr
2,500m = 116mm
3,000m = 107mm

This could represent better ballistic performance from the 17 pdr APCBC projectile, or more likely, it represents much better penetration at higher obliquity, and this would be a decided advantage in combat.

[Soren]

Soren have you data for 77 (Comet guns)? and for italian 90? (i know this is not a tank gun)

On th British 77mm yes, the Italian 90mm, no I'm sorry. The 77's performance is listed below:

77mm HV APCBC projectile against vertical 240 BHN RHA plates:
500m = 137mm
1,000m = 126mm
1,500m = 116mm
2,000m = 106mm
2,500m = 98mm
3,000m = 90mm

[Soren]

The reason for the slightly steeper decline in velocity for the 7.5cm PzGr.39/42 projectile vs the 7.62cm Mk.8T is 1.) Mk.8T is heavier and 2.) The Mk.8T abit more aerodynamically efficient for a reason being described below. For the 7.5cm KwK42 a new version of the PzGr.39 was designed, designated the PzGr.39/42, it was abit heavier at 7.2kg than the older 6.8 kg PzGr.39 used in the KwK40 & Pak40, and abit less aerodynamically efficient as it was designed to perform better against highly sloped armour. In short the 7.5cm PzGr.39/42 APCBC(HE) was designed on purpose to better defeat armour at very steep angles, performing better against sloped armour than the 7.62cm Mk.8T APCBC in US tests.

So while the 17pdr was more effective against vertical plates, the 7.5cm PzGr.39/42 performed better against angled plates. 8.8cm PzGr.39 projectiles of all types were different in design and were amongst the most aerodynamically efficient AP projectiles made during WW2.

Here's the 7.5cm PzGr.39/42, note the unusual design, this was to enable it to better defeat sloped armour:


And the 8.8cm PzGr.39-1, a much more streamlined design, the most aerodynamically efficient projectile fired by any tank gun during the war:

[parsifal]

Soren have you data for 77 (Comet guns)? and for italian 90? (i know this is not a tank gun)

Hi Vincenzo

The 90 mm gun fired a 22.2 lb AP round at a muzzle velocity of 2,756'/sec.6 It's maximum range was 15,000 yards.6 It could penetrate 5.63"@0° at 500 yards.

I t makes for an interesting comparison with the German 88mm series...according to Sorens list the 88 could penetrate 219 mm, at that range whilst the Model 53 could penetrate 143 mm. That seems an awfully big difference

[dunmunro1]

A slightly better ballistic performance doesn't explain the fact that the Panther starts out at 168mm and ends up at 91mm, while the 17 pdr starts out at 163mm and ends up at 107mm, since if the L/70 has better high target angle performance this should offset the increase in target angle at long range which occurs as a natural result of the projectile trajectory.

[Soren]

A slightly better ballistic performance doesn't explain the fact that the Panther starts out at 168mm and ends up at 91mm, while the 17 pdr starts out at 163mm and ends up at 107mm, since if the L/70 has better high target angle performance this should offset the increase in target angle at long range which occurs as a natural result of the projectile trajectory.

It may surprise you to know how flat the trajectory of a 800+ m/s cannon actually is. We're not talking howizter trajectories here.

Also take a look at the 8.8cm PzGr.39-1's performance, it goes from 151mm to 97mm, that's better than both.

[Vincenzo]

Hi Vincenzo

The 90 mm gun fired a 22.2 lb AP round at a muzzle velocity of 2,756'/sec.6 It's maximum range was 15,000 yards.6 It could penetrate 5.63"@0° at 500 yards.

I t makes for an interesting comparison with the German 88mm series

thank you. This is a british test? afaik italian standard AT round had HE fillers so were AP(HE) or APBC(HE)

p.s. unlucky italian 90mm carriage was more large and high of that of 88 so the use as ATG of this AAG was not so easy. (almost this is the common explanation, i not checked but maybe also the italian gun it's longest (the misuration it's not same in italian army and in german army)

[parsifal]

The source says that it was from data obtained at Aberdeen in 1968. I dont know any more than that

[dunmunro1]

Here's data from the same source for the 17 pdr APDS:
500m = 256mm
1,000m = 233
1,500m = 213
2,000m = 194
2,500m = 178
3,000m = 162

Perhaps Soren could post the data for the 6 pdr APDS?

[Juha]

Hello
"Fire and Movement", RAC Tank Museum, Bovington, 1975, pages 22–25. "Penetration v. homogenous armour at 30º, at ranges in yards". The armour is machineable quality.

6-pdr Mk 3 or 5 APDS 131mm@500, 117mm@1000, 103mm@ 1500, 90mm@ 2000

Juha

[Soren]

Here's data from the same source for the 17 pdr APDS:
500m = 256mm
1,000m = 233
1,500m = 213
2,000m = 194
2,500m = 178
3,000m = 162

Perhaps Soren could post the data for the 6 pdr APDS?

Sure can, but like I've said before APDS was a poor ammunition type during WW2, it was inaccurate and poor against sloped armour, had poor killing power once penetration was achieved and in short supply. So I really do not understand why you're so obsessed with this projectile type. APCBC rounds were the most lethal AP projectiles used during WW2, and were prefered for that very reason, Firefly gunners prefering the APCBC over the APDS round.

5.7cm 6pdr L/52 gun with APDS:
500m = 160mm
1,000m = 140mm
1,500m = 123mm
2,000m = 108mm
2,500m = 95mm
3,000m = 83mm

[dunmunro1]

6 pdr APDS 4000fps
0 targe angle MQ armour
500yds=173mm
1000yds = 153
2000yds = 119

http://www.wwiiequipment.com/index.p...tank&Itemid=58

[Soren]

Fits well with the US test results once adjusted into meter results.

[dunmunro1]

Sure can, but like I've said before APDS was a poor ammunition type during WW2, it was inaccurate and poor against sloped armour, had poor killing power once penetration was achieved and in short supply. So I really do not understand why you're so obsessed with this projectile type. APCBC rounds were the most lethal AP projectiles used during WW2, and were prefered for that very reason, Firefly gunners prefering the APCBC over the APDS round.

You've certainly said this and been corrected for saying it, but 6 pdr APDS was not inaccurate and had none of the problems that 17 pdr ammo had. 6 pdr APDS was more accurate than APCBC, and it was available from day one of the Normandy Campaign.

[Soren]

You've certainly said this and been corrected for saying it, but 6 pdr APDS was not inaccurate and had none of the problems that 17 pdr ammo had. 6 pdr APDS was more accurate than APCBC, and it was available from day one of the Normandy Campaign.

You're making one untrue claim after the other. 6 pdr APDS ammunition was not at all more accurate than APCBC, the APDS rounds of the time all suffered from the same problems, and again they were in short supply. And where exactly have I ben corrected on this issue? So far I've only seen you being corrected after making claims again and again and again.