Why does the German Army like 20mm auto cannons so much?

[davebender]

In the evening, we returned to our old positions. There we received the mission to occupy the village behind that high ground the next morning. We were thus supposed to open the way for an infantry regiment. Two more tanks and three 20mm quad Flak guns were attached to me at darkness. The latter proved themselves magnificently in action against ground targets.
Otto Carius

[vanir]

Shaped charges were pretty rudimentary but British and Soviet anti-armour rockets were specially made capable of penetrating 150-300mm of case hardened armour at any angle on a direct hit, upwards. I mean seriously the really big leap made in anti-armour weaponry was made right there in WW2, things like the modern Maverick just refined it. There's a whole catalogue of man-portable and aerial shaped charge warheads with terrific antitank performance comparable to modern weaponry. We just do the same thing better now, not so much a different thing.
Fire a volley, if you hit, guaranteed there aint nothing left of any German superpanzer, no way.


Oh Rechlin testing does put the muzzle energy of a 2cm FlaK shell (assuming a MG151 variation, my German isn't good) up around 3 tons. I guess I'd feel nervous in an old tank. 3cm FlaK is around 14.3 tons though, yeah that would be more disconcerting.

[davebender]

Muzzle Energy.
An introduction to collecting 20 mm cannon cartridges The 20 mm automatic cannon first saw service during World War 1 but achieved its
24,000 joules. 20mm x 80mmRB. MG-FF aircraft cannon.
29,000 joules. 20mm x 82mm cartridge. MG151/20 aircraft cannon.
47 to 60,000 joules. 20mm x 138mmB cartridge. Most WWII light flak such as flakverling.
84,400 joules. 20mm x 139mm cartridge. Modern day NATO cannon such as German Rh202.


An introduction to collecting 30 mm cannon ammunition
42,100 joules. 30mm x 90mmRB cartridge. Mk108 aircraft cannon.
131,500 to 163,600 joules. 30mm x 184mmB cartridge. Mk101 and Mk103 aircraft cannon.
207,000 joules. 30mm x 173mm cartridge. Modern day GAU-8/A cannon employed by A-10 aircraft.

As you can see the cartridge fired by most WWII era German 20mm flak was roughly twice as powerful as as the Mg151/20 cartridge. That's why the Heer rarely used the lightweight and fast firing Mg151/20 cannon.

It's easy to see why a 30mm Mk103 cannon with state of the art ammunition (i.e. uranium) was so capable. Muzzle energy was about 75% of the modern day A-10 cannon.

[Shortround6]

207,000 joules. 30mm x 173mm cartridge. Modern day GAU-8/A cannon employed by A-10 aircraft.

It's easy to see why a 30mm Mk103 cannon with state of the art ammunition (i.e. uranium) was so capable. Muzzle energy was about 75% of the modern day A-10 cannon.

And that is also the reason why the notion of "chewing through" armor with fast firing small cannons is pretty much bunk. Muzzle energy of a Standard German 50mm anti-tank round was 652,000 joules. the APCR round had 900,000 joules. British 6pdr had 989,000 joules. You would need about 4 rounds of the 30mm ammo to hit within 27mm of each other (center to center) to equal the energy application the 6pdr round. Even tighter to equal the German 50mm APCR round. the chances of getting enough 20mm rounds into a small enough area are getting astronomical. 10-14 rounds landing within 30mm center to center to equal regular ammo? The German 50mm was marginal against many Russian tanks using regular ammunition.

[psteel]

Multiple hits on armored plate will progressively weaken the plate. They don't have to be within 3/4 of a projectile diameter of each other.

[parsifal]

The A-10s cannon has a cyclic rate of about 6000 rpm does it not. At that rate you might get a grouping as required. At the ROF applicable to a single barrled cannon....about 800-1000 rpm, it would be difficult to achieve the necessary gropuping to achieve penetration.

I remember also reading somewhere that A-10s dont aim to penetrate the deck armour of enemy tanks. They aim mostly to disable the tank by taking out the tracks do they not?????

[davebender]

I wonder if the composition of modern day laminate tank armor has something to do with it. The ceramic layers must be brittle. Multiple hits might smash it up a layer at a time.

[Shortround6]

Multiple hits on armored plate will progressively weaken the plate. They don't have to be within 3/4 of a projectile diameter of each other.

Maybe not but but they do have to be close. hits 15cm to 100cm away aren't going to get much if any benefit from previous hits. For WW II use you are talking a mechanical accuracy ( accuracy of the gun and ammo bolted to a substantial mount) better than most of the sniper rifles of the time could achieve.

A flak Veirling has got a real problem with 4 different barrels. It may stand a better chance of a "golden BB" going through a vision port or joint than "chewing through" the same spot.

Brittle armor can crack from multiple hits in a small area but depending on your opponent to make bad armor is bad planning for weapons procurement.

[davebender]

There were a lot more things on the WWII battlefield then T-34 tanks.

Soviet Armored Vehicle Production.
Soviet combat vehicle production during World War II - Wikipedia, the free encyclopedia
1,717 x T-26 light tanks.
780 x BT-7 light tanks.
896 x T-40 light tanks.
75 x T-50 light tanks.
5,773 x T-60 light tanks.
8,231 x T-70 light tanks.
101 x ZiS-30 SP guns.
12,054 x Su-76 SP guns. Second most numerous Soviet armored vehicle. Open top makes it especially vulnerable to automatic weapons fire.
1,400 x Ba-10 armored cars.
9,110 Ba-64 armored cars.

Trucks, artillery pieces, artillery horse teams, artillery tractors and horse drawn wagons numbering in the hundreds of thousands.

VVS CAS aircraft numbering in the 10s of thousands.

Soviet infantry numbering in the millions.

[vanir]

I'm at some other aviation websites with ex-military pilots and one has commented at length on how the A-10 does an anti-armour attack, even posted the USAF documented guidelines for taking down a T-72 with the GAU cannon, diagrams and all. They aim at the hull area which is where the wheels/tracks are. Armour is thinnest here. WW2 doctrine however would be the rear/upper plates and the attack angle much steeper.

cyclic rate on the gun is 2100rpm/c. It has a switch for 4200rpm/c but it was troublesome and unnecessary at this speed so was disabled in the 80s update.
cyclic rate for wartime single barrel 3cm guns with any kind of anti-armour velocity is about 350rpm/c in practise. The MK213/3cm was projected for 1200rpm/c and this was achieved in the DEFA copy, which is a rather direct copy of German wartime blueprints. Muzzle energy is up around a Mk103 too, but in a second generation version I think that went into production in the 60s. The original one, ex-German was slightly more powerful than a Mk108 from memory. Tony William's site will have the correct figures.

The real nasty one was the MG213, 1600rpm/c. Even at MG151 shell energy that's a lot of damage.

[psteel]

Maybe not but but they do have to be close. hits 15cm to 100cm away aren't going to get much if any benefit from previous hits. For WW II use you are talking a mechanical accuracy ( accuracy of the gun and ammo bolted to a substantial mount) better than most of the sniper rifles of the time could achieve.

A flak Veirling has got a real problem with 4 different barrels. It may stand a better chance of a "golden BB" going through a vision port or joint than "chewing through" the same spot.

Brittle armor can crack from multiple hits in a small area but depending on your opponent to make bad armor is bad planning for weapons procurement.

Accually they don't have to be close. Pretty much anywere on the plate will do. Modern ballistics are emphatic...one shot per target plate! Doesn't matter if its a shaped charge , APFSDS APDS or APC etc only one shot per target plate or else it skews the data.

[davebender]

I agree.

Schützenpanzer Lang HS.30 - Wikipedia, the free encyclopedia
Why didn't the Heer adopt this weapon for the Schützenpanzer Lang HS.30 during the 1950s rather then purchasing the French made Hs.820 autocannon?

[Shortround6]

There were a lot more things on the WWII battlefield then T-34 tanks.

Soviet Armored Vehicle Production.
Soviet combat vehicle production during World War II - Wikipedia, the free encyclopedia
1,717 x T-26 light tanks.
780 x BT-7 light tanks.
896 x T-40 light tanks.
75 x T-50 light tanks.
5,773 x T-60 light tanks.
8,231 x T-70 light tanks.
101 x ZiS-30 SP guns.
12,054 x Su-76 SP guns. Second most numerous Soviet armored vehicle. Open top makes it especially vulnerable to automatic weapons fire.
1,400 x Ba-10 armored cars.
9,110 Ba-64 armored cars.

Trucks, artillery pieces, artillery horse teams, artillery tractors and horse drawn wagons numbering in the hundreds of thousands.

VVS CAS aircraft numbering in the 10s of thousands.

Soviet infantry numbering in the millions.

I am not the one who brought up the idea of "chewing" through armor. You might also want to do a bit of real reading instead of relying on Wikipedia.

The Flakvierling was first being introduced when quite few of the vehicles on your list were being phased out of production.

The Flakvierling weighed more in action ( and a lot more in tow) than a 7.cm Pak 40 anti-tank gun, it needed a bigger crew and was larger and harder to dig in or hide.

Siting you AA guns well forward to act as ground guns means they are NOT doing a proper job of air defense.

[vanir]

I agree.

Schützenpanzer Lang HS.30 - Wikipedia, the free encyclopedia
Why didn't the Heer adopt this weapon for the Schützenpanzer Lang HS.30 during the 1950s rather then purchasing the French made Hs.820 autocannon?

Believe it or not I smell the distinct odour of political correctness in this decision. The world was still pretty sore on the Germans but the military threat had become the Soviets. This AFV was a Swiss design, by a French company, with a British engine, to be made and equipped in Germany. I think if you whipped out a German wartime gun design on it, you might have seen it in newspapers headlines like, "NATO adopts tools of the devil!"

I think they managed to afford such political luxuries because the IFV had fallen into the background since the defeat of Axis forces and establishment of the Iron Curtain, because it wasn't predominant in US doctrine and the industrial strength of the US clearly led NATO doctrine right from the beginning. The military surplus in the US in 1950 was just ridiculous, you could've laid waste to the planet the old fashioned conventional way with it.

So European tactical doctrine was quickly falling into the background at NATO fronts like Germany. The closest competitors in the IFV stakes at the time used HMG. The Soviets were only just beginning to conceive their infamous motorised rifle battalions, so didn't have that much comparatively in IFV (just tanks and SPG, and of course gazillions of towed artillery).

I think it was a case of the public mind at a time of continuing tensions in Europe. They could've put an Aden in it, it's an MG213 copy too. But people would start complaining, wondering if the Allies of WW2 had gone Nietzchean in the postwar environment with the Russians, and in fighting Germany had become the monster when the abyss had looked back into them.
The general public can be a bit like that, and if they get concerted enough they can shut down a military, or sack a government.


hey just reading further down the article, it even mentions there was a media controversy as it was.

These investigations revealed that key personnel associated with the procurement of the SPz 12-3 had accepted bribes as high as 2.3 million Deutschmarks (DM). Other witnesses asserted the Christian Democratic Union political party received campaign donations totaling some 50 million DM as a result of its support for SPz 12-3 procurement.

I'd say right about then they were saying to themselves, "Gee glad we didn't put that Aden on it."

[Shortround6]

A few reasons they didn't put the 213C were mentioned earlier in the thread. Like cooling the barrel of a high cycle rate gun. Another is wither the 213 was really ready for production, even if the French and British versions were (only took them how many years to get it into service?) another is the feed. Fixed gun (in aircraft) may be easier to feed than a gun the moves in relation to the ammo supply. As far as using the Aden instead of the HS 82) there might be problems with ammo capacity, trajectory, and even penetration. The early Aden gun used a shorter cartridge case and fired a 273gram shell at 604 m/s