If the US is neutral, how does the air war in Europe play out?

[Koopernic]

I'm not sure on NA but at least once during late summer - autumn 1944 3.7"s were deployed to form an anti-tank screen in ETO. They were sometimes used to beef up 21st AG barrages in ETO. Being capable to fire heavy air bursting shells made them nasty to German infantry but the limitiations in their fuzes limited their use in counter-battery role.

Juha

The UK's 97mm 34 pounder was around twice the weight of the German 8.8cm FLAK 37 (keep in mind that there are two weights given for artillery: the travelling weight and demounted weight) and simply didn't have the mobility: the Germans 10.5cm FLAK 39 was about the same size and was found difficult to transport. There were other factors that made these guns unsuitable for anti tank use such as limited depression and lack of gun shield to absorb small arms fire and splinters to say nothing of the massive profile. The Germans would have loved to have these powerful high velocity guns as the could reach higher altitude than both the 8.8cm FLAK and the 10.5cm FLAK,for homeland defence since Mosquito and the USAAF was going unchallenged.

The Beauty of the FLAK 37 is that it was light enough to travel with an army, to provide defence against medium bombers and aircraft up to medium altitude. It could be used in the anti tank role; The Kommandogeräte 40 predictor computer incorporated a 3.5m base stereoscopic range finder that could occasionally get first round hits on tanks 4000m away, though it as often the earlier FLAK 36 that was used in the AT role.

Another advantage is that it was simple: no fancy servo drives, no autoloaders no automatic fuze setters and no electronic technicians required. Fairly unskilled manning could be used. The Germans used Russian POW (USSR refused to sign Geneva convention) and Children the so called FLAK-kinder (there was a machine that set the fuze, the predictor provided enough dead time to load the round and fire it): such things could be accomplished manually.

The US 90mm M2 represents a true dual purpose allied gun, it was common from about April 1943.

The replacement for the FLAK 37 was the 8.8cm FLAK 41, it had a much higher velocity, autoloader, auto fuze setter etc and a very low profile so it could be used as both a FLAK and PAK anti tank. ZIt weighed more but still not as much as the allied guns. To keep the firing rate up and the recoil and weight down it fired on the recoil recuperation stroke. It has some problems with cartridge extraction when the cartridge was changed from brass to steel but this was solved. Problems with vibration and stability at high rates of fire took longer. It might have been a real problem for USAAF bombers, photo reconnaissance F-5 and Mosquito had its production expanded rapidly when it was first introduced. There were at most 100 in service at a time from 1943.

 

[Juha]

Hello Koopernic
I'm well aware of the bulk and weight of 3.7" (94mm) 28pdr HAA gun

The UK's 97mm 34 pounder was around twice the weight of the German 8.8cm FLAK 37 (keep in mind that there are two weights given for artillery: the travelling weight and demounted weight) and simply didn't have the mobility: the Germans 10.5cm FLAK 39 was about the same size and was found difficult to transport. There were other factors that made these guns unsuitable for anti tank use such as limited depression and lack of gun shield to absorb small arms fire and splinters to say nothing of the massive profile. The Germans would have loved to have these powerful high velocity guns as the could reach higher altitude than both the 8.8cm FLAK and the 10.5cm FLAK,for homeland defence since Mosquito and the USAAF was going unchallenged.

Yes, 3.7" was bulkier than 88 but in the few cases when 3.7"s fought tanks in NA (I checked that) they were well dug in as were 88s usually in NA. 88 was also bulky and if not properly dug in appr same height than 3.7". What helped enormously 88s in NA was that the 2pdr armed British tanks didn't have HE rounds contrary the German gun tanks so outside the mg range all they had against A/T guns was the 2pdr shot.

The Beauty of the FLAK 37 is that it was light enough to travel with an army, to provide defence against medium bombers and aircraft up to medium altitude. It could be used in the anti tank role; The Kommandogeräte 40 predictor computer incorporated a 3.5m base stereoscopic range finder that could occasionally get first round hits on tanks 4000m away, though it as often the earlier FLAK 36 that was used in the AT role.

Now the use of Kommandogeräte 40 in A/T role IMHO would not have been the brightest idee, in that case the guns were bunched too tightly for comfort (the connection cables were only certain lenght) and the whole battery (4-6 guns) could engage only one target at a time. In fact only that kind of action was possible if 3.7"s on wartime Mk III mountings were used against moving tanks because the layers seated looking backwards, the mounting was so much opted for predictor use. On the pre-war Mk I mounting the layers faced forward and so could engage moving ground targets independedly.

Another advantage is that it was simple: no fancy servo drives, no autoloaders no automatic fuze setters and no electronic technicians required. Fairly unskilled manning could be used. The Germans used Russian POW (USSR refused to sign Geneva convention) and Children the so called FLAK-kinder (there was a machine that set the fuze, the predictor provided enough dead time to load the round and fire it): such things could be accomplished manually.

Now 3.7" could be also loaded manually and be operated independently only A/T work with Mk III mounting was very problematic. At least without mods that allowed one forward facing layer/gunner to control the gun.

Juha

 

[Glider]

IIRC a modified version of the 3.7in was mounted in the Tortoise self propelled gun so changes would have been possible had the need arisen. However the UK went down the 17pd to 20pd route instead.

 

[Shortround6]

The 3.7in AA gun (94mm) was a pretty good AA gun and most peoples dual purpose or 'triple' threat guns didn't really worked all that well at all three roles, at least not at the same time.

The 3.7in threw a heaver shell, higher than the Flak 36/37 and since nothing is free, it paid for that in weight. The Germans captured some in France in 1940 (?) or other places and thought them useful enough that they made 100,000 rounds of ammo for them when the captured ammo ran low, in 1943. Which points to another advantage of the 3.7in as an AA gun. It had a longer barrel life than the later 8.8cm Flak 41. The Germans got around that, in part, by making the barrel liner in three pieces so only the most worn section/s could be replaced instead of the entire barrel liner.

High velocity AA guns can be used as field artillery (and the 3.7in was) but you better be pretty sure the enemy air strength is low because such use cuts into the barrel life and barrel life is not just the number of rounds before thegun becomes unsafe but the velecity gets lower and lower as the gun wears leading to both a lower effective ceiling and worse "accuracy" as the barrel approaches the end of it's life. Accuracy not only in the conventional gun sense but in the fact that the velocity variation is harder to adjust for in the fire control predictors. If it takes 20 seconds for a new barrel to get a shell to XXX height how many seconds does it take a somewhat worn barrel or a barrel a hundred rounds from replacement?

While the FLAK 37 didn't have "no fancy servo drives, no autoloaders no automatic fuze setters and no electronic technicians required" it did have a follow the pointer system in which pointers were moved on dials by electrical signals sent through cables from a central fire control director ( actually a part analog computer) so a battery needed a generator and at least an 'electrician' or two even if not "electronic technicians". There is also a difference between manual ramming, power ramming and autoloading.

Guns used for anti-tank work for long periods of time tended to "loose" things like the "follow the pointer" parts, cable connections and even the "mechanical" fuse setter which made the guns rather useless for AA work except in the "spray and pray" mode.

And guns laid out (dug in) as AT guns were seldom, if ever, laid out in the proscribed pattern the fire control calculator had been built to use ( a diamond or box around the fire control unit) let alone have the needed cables to run to dispersed gun positions.

The 88 was a very good gun and did a number of jobs and did them well but lets not pretend it could do them at the same time/day or even on successive days.
Neither could the British or American guns, despite press releases

 

[Shortround6]

IIRC a modified version of the 3.7in was mounted in the Tortoise self propelled gun so changes would have been possible had the need arisen. However the UK went down the 17pd to 20pd route instead.

Well.......

........

3.7in on a RAM chassis. Early 3.7in guns had the gun 'pointer" facing backwards and no ground sight. Later versions turned him around and did give him some sort of direct fire sight. But by that time the 6pdr and 17pdr were pretty much handling the AT duties.