AAA, from 45mm to 57mm: a missed opportunity or waste of resources?

[tomo pauk]

The anti-aircraft artillery in calibers ranging from 45mm to 57mm was a rare thing during the ww2. Soviets were using the 45mm AAA in penny packets (mostly/exclusively on their ships), Germans have experimented with 5cm, British with 57mm.
MY questions being whether such weapons would've provided the combatants with better AA means, or those should be regarded as 'neither fish nor fowl', too heavy to replace the 37-40mm guns, and too weak to replace the heavier stuff?

 

[Shortround6]

Most countries realized there was a "hole in the sky" above the height that 37mm-40mm guns were effective and below the height as which 75mm guns and up were effective. The problem came in building a gun to fill the hole. Actually the problem was more in the fuses for the shell and the shells. the 45-60mm shells were too small to have the blast/fragment radius of the 75mm shells, the 47mm bore size being popularly known as the 3pdr and the 57mm the 6pdr vs the 75mm being a 12-17lb projectile. A direct hit was almost necessary. But this called for a much higher rate of fire than the 75mm guns, a rate of fire close to that of the 37-40mm guns, except that the ammo is 2-4 times heavier than the 37-40mm guns.

They could have replaced neither class of guns but could have denied the use of the band of airspace that the light and heavy guns could not effectively cover. The problem was cost, both in money and in engineering time.

 

[Juha]

Most countries realized there was a "hole in the sky" above the height that 37mm-40mm guns were effective and below the height as which 75mm guns and up were effective. The problem came in building a gun to fill the hole. Actually the problem was more in the fuses for the shell and the shells. the 45-60mm shells were too small to have the blast/fragment radius of the 75mm shells, the 47mm bore size being popularly known as the 3pdr and the 57mm the 6pdr vs the 75mm being a 12-17lb projectile. A direct hit was almost necessary. But this called for a much higher rate of fire than the 75mm guns, a rate of fire close to that of the 37-40mm guns, except that the ammo is 2-4 times heavier than the 37-40mm guns.

They could have replaced neither class of guns but could have denied the use of the band of airspace that the light and heavy guns could not effectively cover. The problem was cost, both in money and in engineering time.

I agree with Shortround6
one minor point, 57mm gun would have some A/T potential even against heavier 44-45 tanks as 37-40mm had against tanks in 39-44. See attachment, hits 4 and 10, the latter was penetrating one, are by SU-57-2 AA tank

 

[davebender]

High velocity 20mm with a high rate of fire works just fine for the army. It's exactly what you need when an enemy fighter-bomber makes a high speed pass at an altitude of 10 meters. It's also very effective against enemy infantry and most other ground targets except main battle tanks. 20mm size weapons are easy to transport and easy to dig into a defensive position. 20mm ammunition is light enough that it doesn't add a large logistical burden to ground troops.

If 57mm has any use at all it would be to defend fixed installations. 37mm flak is effective to 4,800 meters (per Wikipedia) and can fire 250 rounds per minute (Flak 43). The post-war Soviet 57mm AZP S-60 has an effective range of 6,000 meters (per Wikipedia) but rate of fire drops to 120 rounds per minute. I'm not convinced that's a worthwhile trade off. But then I'm not an AA gunner. What does our expert think?

 

[tomo pauk]

Until we hear from the expert: I've seen the ZSU-57-2 (2 barreled SP AAA, 57mm cannon) firing at same targets as we did in our Pragas (2 x 30mm), achieving decent results vs. those, rather predictable targets(steady curse, not too low, steady speed) They were longer ranged, 4000m vs. 6000m. Since it takes plenty of time to reach 6000m (almost 12 seconds), the radar in the loop seem like mandatory item, if one wants to really capitalize upon that extra range height.
With 120 rpm, the S-60 ('half' of the ZSU-57-2 armament) was as 'speedy' as the Bofors 40mm L60 of the ww2 fame.

As for the 20mm being just what an Army needs in ww2, seem like no major combatant agreed with that. As for thwarting the attacks made at high speed pass at 10m, nothing short of the radar-cued automatic cannon (or some really good SAM) will cut it, luck being another requirement.

 

[davebender]

As for the 20mm being just what an Army needs in ww2, seem like no major combatant agreed with that.

Perhaps not but the German army isn't just any army. Heer divisions were the most capable in the world during both world wars. We've got first hand testimony from experts like Otto Carius stating flakvierling worked exceptionally well against ground targets. I'm not going to question their professional judgement.

 

[tomo pauk]

If the 20mm was a good thing to employ vs. ground targets, that does not say anything about it's value at it's primary mission, that being killing aircraft - that very German army was puchasing the 37 mm Flak in different 'flavors', while trying to develop, produce and use the 30 and 50mm Flak. Seems like they wanted a bigger stick.

 

[Juha]

SU-57-2, 2x120rpm

 

[Juha]

Soviet 57mm AA gun

 

[Juha]

Most WWII armies fighting in Europe seems to have that 20mm 37/40mm mix, USA had .5 37/40mm mix, Soviet had mg/hmg 37mm mix for automatic AA.

Juha

 

[davebender]

You've got it backward. Killing ground targets is the primary purpose of Heer 20mm weapons from WWI (i.e. 20mm Becker) right up to the present day. The large HE payload of German 20mm shells allows these weapons to function in a manner similiar to the Soviet AGS-17 30mm automatic grenade launcher. Protection against CAS aircraft is just a bonus.

37mm flak was primarily intended for air defense.

 

[Juha]

You've got it backward. Killing ground targets is the primary purpose of Heer 20mm weapons from WWI (i.e. 20mm Becker) right up to the present day. The large HE payload of German 20mm shells allows these weapons to function in a manner similiar to the Soviet AGS-17 30mm automatic grenade launcher. Protection against CAS aircraft is just a bonus.

37mm flak was primarily intended for air defense.

Really, why then 20mm AA guns were given to Army AA units? And even in 1941 PzDivs usually had only 20mm Flak, they got 37mm later on. The other 20mm were 2cm KwK 30 38, the main armament of Pz II

Juha

 

[Shortround6]

You've got it backward. Killing ground targets is the primary purpose of Heer 20mm weapons from WWI (i.e. 20mm Becker) right up to the present day. The large HE payload of German 20mm shells allows these weapons to function in a manner similiar to the Soviet AGS-17 30mm automatic grenade launcher. Protection against CAS aircraft is just a bonus.

37mm flak was primarily intended for air defense.

What a load of horse manure.

1. the 20 X 138 cartridge used by the Flak guns didn't use the high HE capacity ammo until well into WW II so the HE capacity could NOT have been intended for use against ground targets in the early 30s when the ammo the first guns for it were adopted.
2. With the German shells you have either/or situation. Either you have a 120-130gm shell with about 10gm explosive or you have a much lighter shell with a thinner body and twice the explosive but fewer shell splinters/fragments. Small explosions without much for fragments do crap in the open air. Russian 30mm grenades weigh 275gm, have up to 40gm explosive AND a pre notched internal fragmentation sleeve for a lethal radius of 6-7meters.
3. The Russian grenade launcher weighs about 30kg with tripod and without ammo. It is man portable. a single 20mm German AA gun is not. A Flak 30 weighs about 450kg in firing position and about 740kg ready to travel. also without ammo. German 75mm infantry gun only weighs 400kg. Compared to 8cm mortars the 20mm gun in ground mode is a joke for HE delivery.

The German 20mm guns were used against ground targets but it was not their primary purpose either when planned or adopted. The American .50cal was effective against infantry too but that was not the reason it was adopted either. The .50cal was adopted as both an AA weapon AND as an anti-tank weapon. Last time I checked tanks were ground targets so one could say that the .50 was adopted for use against ground targets but it certainly wasn't adopted as an anti-infantry weapon. This was pre WW II when anti-tank rifles were very popular (and effective against the light tanks of the time) so having a full automatic gun that fired an "anti-tank" cartridge was seen as a good thing.

The German 20mm guns were intended for air defense, usefulness against ground targets was secondary. Using your 20mm AA guns to shoot your infantry onto a target or to repel and an attack is fine if it works, Loosing your AA assets to Vickers guns (or Maxim guns) or 3in-82mm mortars and then being hit by aircraft may not seem so smart. The aircraft could show up days (or weeks) later.

 

[davebender]

Originally developed for use in anti-tank rifles and later adopted for use in German light flak. Hence effectiveness against ground targets was known from the beginning.

 

[Shortround6]

Originally developed for use in anti-tank rifles and later adopted for use in German light flak. Hence effectiveness against ground targets was known from the beginning.

Really? and your proof of this is?

20 X 138 cartridge may have first been used in Swiss ST-5 AA gun which was later developed into the Flak 30. The early Swiss built anti-tank rifles started with a fairly low powered 20mm round, moved to the 20 X 105 case (the S-18/100) and finally to the 20 X 138 round with the S-18/1000 model.
British were testing a S-18/100 in 1934, which makes the idea that the Flak 30 used a cartridge developed for a later model than 1934 AT rifle a little doubtful.

 

[tomo pauk]

You've got it backward. Killing ground targets is the primary purpose of Heer 20mm weapons from WWI (i.e. 20mm Becker) right up to the present day. The large HE payload of German 20mm shells allows these weapons to function in a manner similiar to the Soviet AGS-17 30mm automatic grenade launcher. Protection against CAS aircraft is just a bonus.

37mm flak was primarily intended for air defense.

Since the name was 'Flak', not 'Iak', I'd say the purpose of the German 2cm Flak weaponry was indeed to fight 'flugzeug', not 'infanterie' The Luftwaffe was one of the major users, so that further points towards the intended use - killing aircraft. SR6 covered the HE vs. total shell weight ratio.

 

[davebender]

Luftwaffe 2cm, 3.7cm, 5cm and 8.8cm weapons were intended for use against aircraft. The Heer had different priorities.

 

[Juha]

Luftwaffe 2cm, 3.7cm, 5cm and 8.8cm weapons were intended for use against aircraft. The Heer had different priorities.

If so, why Heer gave the 2cm FlaK to its AA units? And where you got the idea that Heeres Fla units were not for AA but for ground support?

Juha

 

[Shortround6]

Luftwaffe 2cm, 3.7cm, 5cm and 8.8cm weapons were intended for use against aircraft. The Heer had different priorities.

How many 2cm, 3.7cm, 5cm and 8.8cm AA weapons did the Heer even have? Many of the "Heer's" anti-aircraft weapons were actually in Luftwaffe units attached to Heer formations as in an a Luftwaffe AA battalion being attached to a Heer infantry division.

The Heer had a lot of 2cm, 3.7cm, 5cm weapons but they weren't the same guns as the AA guns let alone the same mounts.

 

[foxhound]

I agree with Shortround6
one minor point, 57mm gun would have some A/T potential even against heavier 44-45 tanks as 37-40mm had against tanks in 39-44. See attachment, hits 4 and 10, the latter was penetrating one, are by SU-57-2 AA tank

Thx very much for this very usefull photo, and information. It would be interresting to know from what distance the AZP S-60 could achieve this performance ? 500 M ? 1500 M ? If it is above 5.000 M with its HE-T, or HEAT-if it could for the last models ?- it could be a terrible deterrence against figther-bombers, including F-15 E, A-10 and F-22.
Can you give us more details please ?

Thx