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Old 06-02-2016, 08:06 AM   #21
Tomsdad
 
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Default Re: WWII: 40mm Autocannon VS tanks?

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Originally Posted by The Colonel View Post
Also they made that giant rifle grenade for the PAK 36 which apparently could pretty much wreck anything if you could get it to hit.
It helps it's oversized.

HEAT vs. APEX is a bit border line at this point and in some cases APEX is better!

if you look at the Rheinmetall 7.5cm KwK40,, the APEX is 6dx10(2) pi++ with follow up 6d [4d-1] cr ex


it's HEAT round is Dmg 6d(10) cr ex with 4dx4 cr ex linked.

The APEX is 2x as good at penetrating, and has that lovely follow up explosion.


Of course the nice thing about HEAT is you no longer need to get as higher velocity as possible which helps in other areas. Which is why if you give the RIA M2A1, 105x371mmR Howitzer an APEX round it's much closer in penetration to the HEAT round in the description. Or make hand held HEAT launchers, recoiless rifles etc, etc

Last edited by Tomsdad; 06-02-2016 at 08:20 AM.
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Old 06-02-2016, 09:21 AM   #22
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Default Re: WWII: 40mm Autocannon VS tanks?

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Originally Posted by Tomsdad View Post
It helps it's oversized.

HEAT vs. APEX is a bit border line at this point and in some cases APEX is better!

if you look at the Rheinmetall 7.5cm KwK40,, the APEX is 6dx10(2) pi++ with follow up 6d [4d-1] cr ex


it's HEAT round is Dmg 6d(10) cr ex with 4dx4 cr ex linked.

The APEX is 2x as good at penetrating, and has that lovely follow up explosion.


Of course the nice thing about HEAT is you no longer need to get as higher velocity as possible which helps in other areas. Which is why if you give the RIA M2A1, 105x371mmR Howitzer an APEX round it's much closer in penetration to the HEAT round in the description. Or make hand held HEAT launchers, recoiless rifles etc, etc
IIRC HEAT penetration of homogenous plate is pretty much directly proportional to the diameter of the round with the exact maths depending on explosive used, shape of the void and similar things.

The PAK 36's bonus round (looked it up, it's called the Steilgranate 41) was ~6" in diameter. That's roughly the same sort of calibre as a modern ATGM... I assume there were other 6" HEAT shells in WW2 that we could compare performance to...
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Old 06-02-2016, 09:34 AM   #23
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Default Re: WWII: 40mm Autocannon VS tanks?

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Originally Posted by The Colonel View Post
IIRC HEAT penetration of homogenous plate is pretty much directly proportional to the diameter of the round with the exact maths depending on explosive used, shape of the void and similar things.

The PAK 36's bonus round (looked it up, it's called the Steilgranate 41) was ~6" in diameter. That's roughly the same sort of calibre as a modern ATGM... I assume there were other 6" HEAT shells in WW2 that we could compare performance to...

It was more the HEAT vs. APEX out of cannon comparison I was thinking of rather than HEAT vs. HEAT

But it makes the point though, I don't think anyone was firing a 6" HEAT shells out of a gun (that's 150mm, so the largest howitzers)


But you don't need a massive great howitzer to do so, as you can fire over calibre, low velocity HEAT rounds from smaller weapons, the panzerfaust is 150mm* but more effective 6dx3 vs. 7dx2 (and lighter even with it's mount)

Of course you suffer in range etc.


*hmm one has to assume the panzerfaust's warhead was developed from the Steilgranate 41

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Old 06-02-2016, 11:41 AM   #24
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Default Re: WWII: 40mm Autocannon VS tanks?

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The famous '88' started life as an AA gun, it's just firing a high velocity round with long effective range is good for antitank work as well (if you put a AP etc round on it)
The American 90mm and the Soviet 85mm were both derived from anti-aircraft guns as well. And the Soviet 100mm started as a dual purpose naval gun.

One thing about War Thunder (and World of Tanks) is that HE isn't really presented realistically. If an AP shell fails to penetrate, it does no damage. HE shells still do damage, but significantly less. Meaning HE is primarily used when you can't penetrate with AP. That's somewhat true, but the effect only really matters with huge HE charges (heavy artillery) or when you have unrealistic ablative hit points.
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Old 06-02-2016, 12:02 PM   #25
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Default Re: WWII: 40mm Autocannon VS tanks?

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Originally Posted by The Colonel View Post
Also they made that giant rifle grenade for the PAK 36 which apparently could pretty much wreck anything if you could get it to hit.
True, not really relevant to the airplane-mounted autoloading BK3,7 though.
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Interesting point about the lower performing APEX, HT has their penetration as the same as the APHC, both at 7dx4 (2) and the follow up on the APEX is a bonus, do we need an errata here you think?
Yes, that's got to be an error. Some discussion at the end of this thread.
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But it makes the point though, I don't think anyone was firing a 6" HEAT shells out of a gun (that's a 150mm, so the largest howitzers)
HEAT shells for the ISU-152 heavy assault gun (which had a 152mm howitzer) were developed, but not used.
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The old Avalon Hill wargame Tobruk (1942, African desert, individual vehicles or infantry squads) included the Bofors 40mm AA gun. It was a fearsome anti-tank weapon in that game because of the rate of fire. The combat system was quite simulationist, obsessed with armor values and round penetration, and had a chart for detailed hit location on a tank (tracks, hull, etc) including a small chance to hit the turret ring between the hull and the turret. This occurred on a 2d6 location roll of 12, so a 1-in-36 chance to hit the turret ring, which would kill just about any tank. And while the Bofors penetration was not remarkable, it did have RoF 40. So odds were if you shot at a tank, you'd kill it.

(And even if not, an M-kill on the tracks was extremely likely.)
...Also, in North Africa, you're not going to be finding many well-protected tanks.
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Old 06-02-2016, 12:25 PM   #26
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Default Re: WWII: 40mm Autocannon VS tanks?

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...
Yes, that's to to be an error. Some discussion at the end of this thread.
fair enough, (and yeah it makes sense given the APEX damage reduction in the write up on APEX rounds later, and that the HE damage and APHC damage are both based on 7dx4, and you see the x0.7 HE to APEX mod in the 75mm write up later)

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.HEAT shells for the ISU-152 heavy assault gun (which had a 152mm howitzer) were developed, but not used.
Cool
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Old 06-02-2016, 12:30 PM   #27
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Default Re: WWII: 40mm Autocannon VS tanks?

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fair enough, (and yeah it makes sense given the APEX damage reduction in the write up on APEX rounds later, and that the HE damage and APHC damage are both based on 7dx4, and you see the x0.7 HE to APEX mod in the 75mm write up later)
Plus the fact that the APHC round existed, at considerable expense in rare metals, to give better penetration than the basic shell. And penetration data indicate that it worked.
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Old 06-02-2016, 02:14 PM   #28
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Default Re: WWII: 40mm Autocannon VS tanks?

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not quite sure what you mean by 'might'. WW2 tanks were quite happily knocked out by planes with cannon in WW2 without having to be parked in garages?

Imagine a bunch of those German 37mm cannon flying around overhead of Shermans at (Dmg 7dx4(2) pi++). with a 2d [2d] cr ex follow up vs. top deck DR50 and HP 158.
The Germans also had that Junkers Ju-87G with the 37mm cannon pods for use against vehicles.
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Old 06-03-2016, 12:21 AM   #29
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Default Re: WWII: 40mm Autocannon VS tanks?

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Originally Posted by Ulzgoroth View Post
Plus the fact that the APHC round existed, at considerable expense in rare metals, to give better penetration than the basic shell. And penetration data indicate that it worked.
Yep good point.

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The Germans also had that Junkers Ju-87G with the 37mm cannon pods for use against vehicles.
Yep, it was on a couple of ground attack planes.
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Old 06-03-2016, 06:12 AM   #30
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Default Re: WWII: 40mm Autocannon VS tanks?

The only time I have heard of WW2 40mm cannon being used against tanks (on a ground mount) was during the Pacific War, where early in the Burma battles the British used them against the Japanese. From what I remember to little effect, and this was against Japanese tracked coffins. While it will be partly down to ammunition type, and the British did have a weird obsession with specialising their guns and sticking to it, but it can't have been the only reason surely?

There is an issue with Savage World's presentation of the Bofors 40mm in their Weird War 2 sourcebook, as it is by far the most effective anti-tank gun of the game, aside from against the heaviest of tanks. Now, it isn't exactly a simulationist system, but even with the awkward things in the book (the British 2 pdr is better than the 6 pdr anti-tank gun) it stands out as particularly off. It has RoF of 4 (the same as an MG42) when according to the way the game is scaled it should probably have a RoF of 2, and armour penetration exceeding most of the "medium" AT guns of the game (the German 50mm, British 6 pdr etc).

Last edited by borithan; 06-03-2016 at 06:20 AM.
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