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

[Karl]

Hi buile,

maybe i can help you.

avin wrote:
------------------------
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
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Avin, where did you get these belting numbers ? Please sources ?


The problem is, there are much different belting setting for special targets.
I am sure, that "Reichverteidigungsgruppen" like JG300 used different belting like JG at east or west front.

Lets see,
Belting:  Stand 03.44
-----------------------
2cm
a) Jäger westfront:
   1 M-Geschoß-Patr.
   1 Brandgr. Patr.
   1 Panzerbrandgr. Patr.

b) Jäger eastfront:
   3 M-Geschoß Patr.
   1 Brandgr. Patr.
   1 Panzerbrandgr. Patr.

c) Kampf u. Schlachtflieger
   3 M-Geschoß Patr.
   1 Brandgr. Patr.
   1 Panzerbrandgr. Patr.
   
I found no sources about the belting for the
"Reichverteidigung" Geschwader like JG300 .
I am sure, they use against 4 Mot Bomber different Belting than Jäger.

Karl

[Toad]

"The same calculation at a target distance 1000m the values are 57 and 51
rounds per hit."

Is this saying that at 1000m you get about 1 hit for roughly 50-60 rounds fired?

[Karl]

first i have to thank you buile for
lighning me up for avins problem .
- - -

here we go.

Avin,

the Documents show 18 Hits  20mm ( 18.2 nitropenta) to shoot down a bomber.
Thats a average number and we can used this as ok.  But now i understand you problem and maybe the misunderstood from other people.

you wrote:
-----------
However, if 18 refers only to the Mine shells, then in reality it took 45 20mm shells on average to
-----------
Yes you are right, this numbers can change on
different belting setting ( see uper post).
Even the number 45 is statisticle, while it can changed on different target range.
remember:
MG151/20 : 11 x 18 = 198 at 500m targetrange.
This numbers are statisticle if you shoot
M-Schell rounds only. If you based the belting mix, you have to shoot much more than 198 shells to get 18 M-Schells hits.


Karl

[This message has been edited by Karl (edited 04-13-2001).]

[This message has been edited by Karl (edited 04-13-2001).]

[Karl]

Hi toad,

you wrote:
----------------------
Is this saying that at 1000m you get about 1 hit for roughly 50-60 rounds fired?
----------------------

i can give you a  " YES " you are right. 1 hit / 50 - 60 rounds.
Thats why the Luftwaffe got the command to get close to fire. Planes with 30mm Cannons have to open fire less ! 300m or closer !.

Karl

[buile]

 

Avin, where did you get these belting numbers ? Please sources ?

I think i told Avin a basic loadout of 2 Mine rounds per 5 in the belt-- regardless, you can find a basic belting from emmanuel gustin's site.  Yes, the belting can change, but i think it's good to be conservative.

 

If you based the belting mix, you have to shoot much more than 198 shells to get 18 M-Schells hits.

My personal view is that it's not 18 hits of Mine rounds in total combined with every other type possibly fired.  Using a ratio of 2 M-geschoss per 5 round fired (we'll say the rest are HE/I), i think you'll start getting things like 10 Mine rounds + 15 HE/I (25 avg) or 12 Mine rounds + 18 HE/I (for 30 round avg)... more?  Yes possibly, but IMO, not 18 Mine + 27 HE/I as an average.

 

This numbers are statisticle if you shoot M-Schell rounds only.

Yes, that's exactly what Avin is asking about.  And since we shouldnt be shooting all M-geschoss, then we cant use that number as a *cut-and-dry* benchmark for flight sim damage models.

buile-

[This message has been edited by buile (edited 04-13-2001).]

[Hooligan]

From:

"The Development of German Aircraft Armament to 1945", USAF Historical Studies #193, Oberst Ing
Page 32

 

(Luftwaffe) Tests had disclosed that it was not the grenade splinters but the blow-back effect of the thin-walled mine projectiles which brought about large-scale damage combined with incendiary effect in the aircraft hit.  The effectiveness of 20mm, as compared with 30mm mines, was approximately 1:4, and in 1944 four or five hits by 30mm projectiles, concentrated in a relatively small area, were necessary to bring down a four-engine bomber.
…..
The initial experiments revealed that 420g-450g of explosives were needed in order to bring about the desired total damage to the fuselage or wings of a large bomber.”

This 420g-450g explosive content requirement led to the development of the German 55mm aircraft cannon.  For reference, a mk 108 30mm round contains 72g of explosive/incendiary mixture

From this source and what Karl has said I think it is likely that the requirement is for 18 2cm Mine shell hits within a relatively small area.  I would like to hear if Karl has anything further to add on whether or not it was a requirement for the 18 Mine round hits to be fairly concentrated.

The Germans increased the ratio of Mine shells when the expected target was a 4-engined bomber.  Since apparently a consideration for including HEI/T was their tracer properties and since we are speculating anyway:  It would make sense for a bomber mission to belt something like 4 Mine, 1 HEI/T.  20-25 hits from this belting would yield something close to 18 Mine hits with a few added HEI/T hits.

Since the standard belting in the West was:

 

2cm
a) Jäger westfront:
1 M-Geschoß-Patr.
1 Brandgr. Patr.
1 Panzerbrandgr. Patr.

That is:
1 Mine
1 Incendiary
1 AP/I

One can only assume this is an anti-fighter belting, as opposed to a Mine-rich anti-bomber belting.  This leads to 2 conclusions:   1) That against Western fighters, incendiary and Armor Piercing rounds were more desirable than Mine rounds.    2)  That a Mine-rich belting optimized for 4-engined bombers would not work as well as the standard belting against enemy fighters.  I would also be particularly interested in Karl and Tony Williams think of these conclusions.

Hooligan

[buile]

Apologies for jumping in.

 

This leads to 2 conclusions

I cant say if Mine rounds were less effective vs fighters or not. To quote Karl's translation:

 

1) based on the expierience we have in the last month of war, we need only 2 kinds of Ammo for destroying flying targets.

It suggests that a Mine/Incendiary mix would do the job if they include fighters as a "flying target."  I would think that the pressure effect would remain effective against a fighter and its smaller airframe.

I'd like to verify this next part, but i seem to remember the Mine rounds were favored against the heavily armored IL-2. Where the AP ammunition had a tough time versus its armor, the Mine rounds were extremely effective at tearing away the rest of the plane around that armor.  Therefore in the end, it was more effective than AP.

I have also heard that there was a supply issue with Mine rounds.  Can anyone confirm this and/or its extent?  That could provide another reason to suggest not using a lot of Mine shells in an anti-fighter role when there's abundant AP or Incendiary to use up.  Ie, youre in a situation where you have possible shortage of a round that works well vs bombers and fighters, and you have an abundance of rounds that work well vs fighters, but not quite as well vs bombers.  The suggestion to save the Mine round for the bombers seems obvious if that's true.  

 

That against Western fighters...

What could be possible differences between the two fronts that will give different results?  I wouldnt think it's strength of armor because of the IL-2.  Anyone have other ideas?

 

I would like to hear if Karl has anything further to add on whether or not it was a requirement for the 18 Mine round hits to be fairly concentrated.

As i mentioned before, i'm afraid of people becoming *overly* strict in their interpretation of what "fairly concentrated" or "relatively small area" means.  I can see people envisioning this as a 6 foot by 6 foot area, and i simply dont think that was the case.  I think we've all seen the results of RAF tests of 20mm ammunition on static examples of wings with fuel tanks (thanks to whoever provided those for us); the rounds were effective in setting them alight under the test conditions.  It wont take 18 Mine shell hits to a fuel tank to set it on fire.

So, imo, where you are on the bell curve depends on where your strikes mostly occur:  if you're hitting a less-vulnerable area like the fuselage (which has less chance of fire), i'd think you'd need a larger amount of hits for good concentration to achieve massive structural failure.  If youre hitting vulnerable areas like the wings, you dont need to use the explosive to brute-force a massive structural failure; you just need enough hits to ensure the fuel tanks or engines are damaged to the point of fire.

This is a heartless subject isnt it?  

buile-

[Tony Williams]

I wouldn't get too hung up on exact numbers of hits required.  They would only have been approximate averages and in practice bombers were doubtless brought down by only one hit, and conversely survived dozens.

I suspect that M-Geschoss were considered more important against bombers than fighters because of the density issue.  There wasn't much empty space in fighters, except in the rear section.  Hits scored were statistically more likely to hit armour or engines, so some AP capability was useful.  Bombers, on the other hand, were full of empty space through which AP would pass without doing significant damage.  This is where the ability of the M-Geschoss to strip away aircraft skin by blast effect came in.

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/

[Hooligan]

Buile wrote:
 

but i seem to remember the Mine rounds were favored against the heavily armored IL-2...

I believe you are wrong on this.  Here is a quote from Gustin's ammuntion page concerning the belting of the 20mm Mg151.

 

20 mm (MG-FF, MG 151/20)
2 Minengeschoß m. Zerl.
2 Brandsprenggranatpatronen L'spur m. Zerl
oder Brandgranatpatronen
1 Panzersprenggranatpatrone o. Zerl
oder Panzerbrandgranatpatrone (Phospor) o. Zerl.

Here the Minengeschoß appears for the first time. A version of the 20mm M-Geschoß with tracer did not exist, so tracer was used on HE/I (Brandsprenggranatpatrone) or pure incendiary (Brandgranatpatrone) rounds. The latter was apparently a new development in 1944, intended to replace the less effective HE/I. The fifth round was a semi-AP projectile, explosive or incendiary. Apparently the main reason this was used instead of a solid AP round was that a solid projectile would have been too heavy.

It was recommended that more AP or semi-AP ammunition would be loaded when the probable targets were well-armoured attack aircraft such as the Il-2. On the other hand, against the four-engined bombers of the RAF and USAAF the high explosive types were more effective.

The Mine round was apparently not that effective against IL-2 and the Germans used an AP-rich mix when IL-2s were the intended targets.

I also consider it improbable that a shortage of Mine rounds was the reason for the belting against Western fighters.  Consider the belting used on the East front.  Karl wrote:

 

b) Jäger eastfront:
3 M-Geschoß Patr.
1 Brandgr. Patr.
1 Panzerbrandgr. Patr.

Or
3 Mine
1 Incendiary
1 AP/I

Why would they be using a Mine-rich belting on the East front if Mine rounds were in short supply?  Does it make sense to sacrifice a Mine-rich belting as the standard on the Western front where you would expect to frequently run into 4-engined bombers so that you could use a Mine-rich belting on the Eastern front?  I think not.  I don’t that supply problems with Mine rounds was the driving force behind the belting arrangements.

I believe that Mine rounds were simply less effective against Western fighters because of their very poor armor piercing capabilities (much worse for example than Hispano HE/I rounds).  After all, US fighters were the largest, most durable and best-armored fighters of the war (excepting the especially modified German bomber interceptors).  The value of AP-type rounds against these exceptionally well-protected US fighters seems obvious to me.  By Western standards, Soviet fighters were rather small and lightly armored, thus the higher proportion of Mine rounds recommended for the Eastern front belting.

Hooligan

[GRUNHERZ]

US fighters are heavily armored. LoL are you nuts?
Exactly which areas of P51 are heavily armored? Where is the surface skin of the P38 armored. Granted the P47 is tough but where is its entire surface armored? Did it have 10mm thick steel skin everywhere? They were well built but not armored, for gods sake please guys stop the constant feel good flag waving.....
Armor plated P51s I love it, damn thats funny. As for mine shell penetration all it has to penetrate is the outer skin of a plane, which is usually thin aluminum then it blows apart the structure with massive overpressure caused by the explosion. So unless a plane has heavy external surface armour it presents mineshells no problem. Il2 actually had 8-10mm thick STEEL plates as an integral skin surface in many areas, this is why a higher  AP load was called for and why HE rounds were less effective.
Which one of you here belives US fighters has 10mm thick STEEL outer skin, show of hands please......


If As you say Mineshells were good vs heavy bombers why wouldn't they be vs small fighters, maybe im  off base but I think some of u guys are afraid if a mineshell comes to AH. O yes and as for your guys supposed mineshell "test", I dont think its valid. Hangars and planes dont have the same damage model. So when you do a real and valid test tell me bout it, till then im convinced that mishell isnt presently in AH MG151/20.

[Karl]

HI,

only 1 remark:

1) If Target = 4 Mot Bomber then different Belting Mix than a) .. Westen.
   I have not the exact numbers. But they used much more M-Schells.


[This message has been edited by Karl (edited 04-14-2001).]

[Vermillion]

Grunherz, why don't YOU do that test ? If you don't believe what work has been done in the past is correct, step forward and prove your point.

You always seem so quick to complain, criticize, and down right squeak and moan, but I never see you step forward to do any of the actual work.

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

[Toad]

Thanks, Karl.

I just thought that was a pretty interesting fact, given all the players here that have assured everyone that any hit at 1000 meters is simply impossible.

Interesting thread.

[GRUNHERZ]

CC Verm what kind of test procedures would you reccomend, what kind of errors should I watch for, seriously?

[Hooligan]

Grun:

As you know, no fighters had armored skin or anything like the armor coverage that a sturmovik had.

However US fighters typically weighed 25% more than their European counterparts and had better armor coverage for the pilot, parts of the engine etc...  The reputation of extreme toughness that P-47s, Corsairs and Hellcats had was well deserved.

There is no doubt that Mine shells were effective against US fighters but the evidence suggests that other types of rounds (AP/I, Incendiary) were more effective than Mine rounds.

Or do you believe that the Germans were idiots for selecting the belting they did to use against Allied fighters?

Hooligan