German data on Mine shells to shoot down 4-engined bombers

[avin]

This one has me a little perplexed.

We're all familiar with German comparisons of the ability of 20mm and 30mm cannon to destroy 4-engined bombers. It's the source of the widely-quoted 4 30mm shells versus 18-22 20mm shells to shoot down a buff.

Here is one quote from such a document:
 

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Fuer die einzelnen Kaliber ist folgende Anzahl von Treffern erforderlich, um den Abschuss eines viermotorigen Bombers zu erzielen:
 
Kaliber 2 cm, Minengeschoss, Sprengladung 18 g, 18 Treffer,
Kaliber 3cm, Minengeschoss, Sprengladung 72 g, 4 Treffer
    ....
-----------------

What I can't figure out is whether the number for 20mm shells refers to total 20mm hits, or to Mine shells only.

Belting for the MG151/20 was 2 Mine shells out of 5, with HE/T (2.3 gms of Nitropenta) making up the remaining 3 out of 5 shells. As Tony has previously told us, the HE/T was retained because unlike the 30mm Mine shell, the 20mm Mine shell wasn't a tracer, and this was considered important.

If that 18 refers to total 20mm shells, then the total amount of HE needed was much less when shooting 20mm than when shooting 30mm, for the same effect.

For 30mm: 4x72 = 288 gm Nitropenta

For 20mm:
18 shells - 2/5 are Mine, 3/5 are HE/T
=(18 * 2/5 * 18.6) + (18 * 3/5 * 2.3)
=159 gm Nitropenta

That's a really surprising result to me. I would have expected it to be much more efficient to detonate a large amount of HE in one place, rather than spread it in many smaller explosions.

However, if 18 refers only to the Mine shells, then in reality it took 45 20mm shells on average to down a 4-engined bomber, as Mine shells were only 2 out of 5.
Now, the total amount of HE becomes:
=(18 * 18.6) + (27 * 2.3)
= roughly 397 gms Nitropenta

This is more in line with my expectations, but it does mean that the oft-quoted 18-22 20mm shells to down a heavy bomber is wrong. It took 45 shells.

Any insight into which interpretation is correct? Is Tony still around?

Thanks,

avin


[This message has been edited by avin (edited 04-08-2001).]

[Hooligan]

To me it seems to quite clearly state that 18 2cm Mine rounds containing 18g of explosive is the required amount.

Sprengladung means explosive content

Your quote means "more or less":

For the individual calibers the following number of hits is necessary to obtain the destruction of a four-engined bomber:

2 cm: mine projectile, explosive charge 18 g, 18 hits
3 cm: mine projectile, explosive charge 72 g, 4 hits

18x18g = 324g
4x72g = 288g

I suggest you email gerzz or ireg and ask their opinions.

In my opinion neither of your interpretations is likely to be correct (i.e neither 18 rounds or 45 rounds of a typical mixed belting).  The figure of 18 mine shells is very likely a theoretical number not empirical.  i.e. they did static tests on captured bombers or bomber components on the ground and created a theoretical requirement of 18 mine round hits.  However since a pure mine belting was unlikely this probably meant that something like 300g to 400g of explosives delivered by 20mm rounds would do the trick.

Hooligan

[Tony Williams]

I can't add anything to the debate about what the Germans meant precisely, but I expect that the belt mix for the 20mm varied according to circumstances.  The mine shell was clearly regarded as important and in fact a bigger 20mm version (105g, with 25g HE) was developed.

The Germans later calculated that to down a bomber with a single hit, 500g of HE was required, which led them to develop 55mm calibre guns at the end of the war.

Incidentally, the standard 30mm M-Geschoss did not have tracers.  The method of construction made it difficult to achieve this, although they were working on designs at te end of the war.

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: http://www.users.globalnet.co.uk/~autogun/

[funked]

FWIW at the 2000 WarBirds Con, Franz Stigler said that 6 to 8 MK 108 hits to the wing of a B-17 would cause the wing to fail.

[avin]

Guys, there are two separate points:

1) As hooli says, these might be theoretical estimates. I'll track down the source - I seem to remember being told they were from gun camera. But what you guys agree with me on is that because of variable loadouts, these estimates can't be used uncritically, as so many LW enthusiasts do. In the field, it would have taken more on average than 18 20mm and more than 4 30mm Mine shells, based on the loadout. Perhaps considerably more.

2) The basic question I'm asking: do we expect the same amount of HE to do more damage when it all explodes in one place, versus broken up into multiple smaller explosions? This is a question at the heart of modelling weapons accurately in flight sims.
I'm guessing that it depends on what you hit, which means that the only way to figure this out is to run a decent simulation.

avin

[StSanta]

An even better question is when will we see the minegeschoss in Aces High?

hispanos got the best of both worlds, LW is stuck with the least effective round.

It's a conspiracy, I tell you  

------------------
Baron Claus "StSanta" Von Ribbentroppen
Staffelkapitän 9./JG 54 "Grünherz"
"If you return from a mission with a victory, but without your Rottenflieger, you have lost your battle."
- D. Hrabak, JG 54 "Grünherz"

[Hooligan]

Avin:

I recommend that you obtain the following book via interlibray loan.

The Development of German Aircraft Armament to 1945
USAF Historical Studies: No.193

Reading it may shed a little light, and as I recall it is available at a couple of libraries close to you.

Hooligan

[Vermillion]

Luftwaffe fanatic wrote:
 

An even better question is when will we see the minegeschoss in Aces High?

Ummm... about a year and a half ago?

------------------
Vermillion
**MOL**, Men of Leisure

[funked]

Yep Verm, unless the results of the Dinger/Hooligan tests have changed, you are right.  No other way to explain those results.
Sorry for hijack Avin, I'm moving along now.  

[This message has been edited by funked (edited 04-09-2001).]

[Sturm]

 

It's a conspiracy, I tell you.  StSanta

Another satisfied X file watcher.  

At any rate the 151/20 seems to hit awfully girlish.  If we got the Minengeschoss shell I bet we have AP loadouts for the FW 190 F8 as well too huh  

------------------
Sturm6 StaffelKapitän
JV44 Platzschutzstaffel
Airfield Defense Squadron
Campaigning for the rights of the ME-410.

[Wilbus]

It required about 20x20mm hits from a MG151 to bring down a heavy buff, have it descired in several books including Adolf Gallands Book.

It's not 20x20 minenshell hits, it's the total of 20x20mm hits.
3-5x30mm hits were usualy required to bring down a buff.

Remember, in AH you actually have to take the wing (or any other very importnatn piece) of a plane to bring it down but in real life it was enough to make it full of holes and that way it would go down and maybe get a crash landing.

In AH you can put 3x30mm in eachi wing of a B17 and a few more in the fuselage, as long as he doesn't actaully loose anything he still flies as good.



------------------
Rasmus "Wilbus" Mattsson
III/JG5 Eismeer

[Vermillion]

 

I bet we have AP loadouts for the FW 190 F8 as well too huh

Didn't Tony post some penetration data on MG151/20 AP ammunition, that showed that it wouldn't penetrate the armor of a Panzer MkIV?  So It wouldn't matter either way with the units we have in AH.

And the MG151/20 already kills the M3 and M16 halftrack units quite nicely, and not to mention that we all know the Ostwind is seriously porked.

Its a moot point, the whole armor system for the game is being changed anyways.

Funked, I ordered the TM 9-1985 series last week on WWII German Munitions (both bombs, rockets, and projectile ammunitions). Email me if you would be interested in a copy.

------------------
Vermillion
**MOL**, Men of Leisure

[Sturm]

Verm it might matter considering that the 17 and lanc are armored fortresses    At any rate, new armor model will probably mean more squeakin.  My Hispano cant kill in 3 hits now will be the first one    Anyway, MG 151 is lacking and we all know it, its a fact and we should be up to par soon i hope.

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Sturm6 StaffelKapitän
JV44 Platzschutzstaffel
Airfield Defense Squadron
Campaigning for the rights of the ME-410.

[Raubvogel]

 

Originally posted by Vermillion:
Didn't Tony post some penetration data on MG151/20 AP ammunition, that showed that it wouldn't penetrate the armor of a Panzer MkIV?  

Actually, the data he posted showed that it should penetrate the armor in certain areas.

[Karnak]

In tests I did with my roommate, he removed my Lancaster's wing with 12 rounds from his P-38L's 50cals.  3 rounds from each gun, no 20mm.  Those 12 rounds removed the inner section of my Lanc's right wing.

The problem it sounds like you guys have is that you aren't accurate enough.  The total amount of punishment that a Lanc or B-17 can take is impressive, but its individule sections can't take much.  If you focus on the outer or inner section of either wing (don't switch between wings) it will quickly pop off, dooming the bomber.  If you spread your fire over the entire bomber though, it will absorb a tremendous beating and remain in the air, under control.

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We few, we happy few, we band of brothers;
For he to-day that sheds his blood with me
Shall be my brother

Bring the Spitfire F.MkXIVc to Aces High!!!

Sisu
-Karnak