Test results of munitions required to destroy a VH at a V Field

[Karnak]

I should add that in no way do I think these ratios translate to air-to-air combat. I know that the 20mm cannons aren't hitting aircraft 9 to 12 times harder than the heavy machineguns.

[Tony Williams]

A few comments:

The HE content on AP shells is probably not relevant as the fuze would only have triggered on (actually, slightly after if it worked properly) impact with armour.  A lighter structure wouldn't have done the job.

The 20mm was about three times as effective as the .50"

The RAF reckoned that there wasn't much difference in the effectiveness of the German and Allied 20mm.  The Hispano could penetrate deeper and do more structural damage, but the M-Geschoss had more blast effect.  Which did nore damage depended on exactly where they hit.

The effect of cannon shells on a building like a hangar is (theoretically) interesting. To work properly against aircraft, shells were fuzed to detonate after penetrating a couple of feet.  Blast effect was greatly magnified by being concentrated in a small space (which is why the M-Geschoss was more effective against bombers when fired into their wings rather than the fuselage).  A hanger is a very BIG space so much of the blast would have been dissipated.  Instant-action fuzes would have been more effective, but the air forces regarded these as not very useful against aircraft. AP would have done little damage.  Probably the best bet would have been to use incendiaries and hope that you could set light to something inside the hangar and burn it down....

Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
NOTE NEW ADDRESS http://website.lineone.net/~a_g_williams
Gun and ammunition discussions at: http://www.delphi.com/autogun/messages

[Vermillion]

The only way the MG151 has more HE content than the Hispano is if you consider it to have a pure mine shell belting to the ammunition.  Something of which I have NEVER seen historical proof.

If you look at a mixed belt (what AH represents) ie the Allied late war standard of 1 AP - 1 HE, and the German late war standard of 1 AP - 1 HE - 1 Mine (from memory its on Gustins website), you will see that the HE content of the two mix's is almost equal.  

Therefore Funked's point about the historically greater kinetic energy of the Hispano, but the ingame results show that the difference in lethality is not there, is a very valid point.

Nice test Karnak  

[GRUNHERZ]

Verm.

The problem with AH "mixed" belting is that each Hispano round has the full HE and full AP performance. Thats the way they model it for the Hispano. There is only one bullet that has both AP and HE modeled to full.
 
They model the MG151/20 the same way each round has the full HE and full AP. If the mineshell was modeled at all ( I dont think it is) then every MG151 shell should have a full mineshell and full AP.

The way we have it now the Mg151/20 is weaker in hit power than the Hispano, if Mg151/20 had any sort of mineshell modeling it would be even or the Mg151/20 would have greater destructive power.

[Karnak]

GRUNHERZ,

 

The problem with AH "mixed" belting is that each Hispano round has the full HE and full AP performance. Thats the way they model it for the Hispano. There is only one bullet that has both AP and HE modeled to full.

Have they said this?

I'd expect that the Hispanos would be a lot more effective if this were true.

[GRUNHERZ]

This is what im told by all the "AH expert" know it alls. It certainly might be wrong, but thats what I hear olver and over. Anyway it think it sucks that HTC doesnt just come out and say how they do it.

You think the hispanos can possibly (should?) be more powerful than they are now....   Oh lord?

[GRUNHERZ]

Mind you I really dont care how the guns are now all that much anymore, the whole thing is not to get into position to get shot at in the first place. Except for some of that 900yard bizzare toejam.

[Karnak]

GRUNHERZ,

Heh.  No, I don't think that they should be better than they are now.  It just seemed to me that they would be a lot better than they are if they were modeled like you described.

If they are modeled with 100% AP and 100% HE, and yet manage to obtain a number only 15% better than MG 151/20s modeled at 50% AP and 50% HE the Mg 151/20 would have to be an absolute monster.  That would imply that if the MG 151/20s were modeled at 100% AP and 100% HE they would do about twice the damage that the Hispano MkIIs do.

Formulas (100 is used as the damage that the MG 151/20s do in AH):
 
115/2 = 57.5 (Hispanos modeled at 50% AP and 50% HE)
100*2 = 200 (MG 151/20s modeled at 100% AP and 100% HE)

57.5 against 100 or 115 against 200.  That would make the MG 151/20 out to be, by far, the most damaging 20mm cannon, doing more than the Russian HV 23mm cannon.

In that case the MG 151/20 would have had these characteristics when compared with the Hispano MkII:

Higher rate of fire than the Hispano MkII.
Much lighter than the Hispano MkII
Vastly more damaging than the Hispano MkII
More reliable than the Hispano MkII
130 meters per second lower muzzle velocity than the Hispano MkII
Lighter, smaller shell than the Hispano MkII

[ 11-21-2001: Message edited by: Karnak ]

[GRUNHERZ]

I think the modeling of the MG151 ammo is identical to that of hispano. I belive both have full AP and full HE modeling in each shell.

What I dont think is that the MG151 has any modeling of Mineshells in any form.

[GRUNHERZ]

BTW your summary at the bottom is pretty much accurate and is prolly why many people say the MG151/20 is one of the best overall if not the best 20mm cannon of WW2.  

[HoHun]

Hi Vermillion,

>If you look at a mixed belt (what AH represents) ie the Allied late war standard of 1 AP - 1 HE, and the German late war standard of 1 AP - 1 HE - 1 Mine (from memory its on Gustins website), you will see that the HE content of the two mix's is almost equal.

The effect of explosives is not linear, and simply adding up might lead to false conclusions here.

The mine shells were designed to explode within the aircraft structure and destroy the load-bearning aircraft skin. A small charge would blow a hole in the skin, and the damage would be confined between the ribs or stringers the skin was rivetted to.

A larger charge would blow a larger hole into the skin, and addionally rip the skin from the rivets and destroy the load-bearing capabilities of the adjacent skin panels as well. This would weaken the aircraft structure much more seriously than two smaller, confined holes would have done.

As a result, one mine shell was considerably more desctructive against aircraft targets than two conventional high-explosive rounds, even when their combined charge weight was equal to that of the mine shell.

Regards,

Henning (HoHun)

[Karnak]

GRUNHERZ,

I think the summary was accurate, except for the "Vastly more damaging" bit.

I think that the MG 151/20 would be more effective against bombers and less effective against fighters than the Hispano MkII.

In any case, it doesn't take a lot of 20mm hits fram any cannon to render a fighter, or even a medium bomber, inoperable.

[Vermillion]

HoHun, I know that. But for the purposes of this discussion its accurate enough without having some really high end explosive simulations software.

FYI the effect of explosives is linear, ie the energy liberated by the explosives themselves. Its the application of that energy, ie the shockwave, fragmentation, and other transmission effects, that is not linear.

And thats not even getting into issues such as fuzing.

[GRUNHERZ]

Exactly Hohun! And thats why the Mk109 30mm is soooo nice.  

[Karnak]

I am definately developing a fondness for the MK 108 30mm.  It hits SO hard.