. . . in the First U.S. Army. From the FUSA Report of Operations for 1 August 1944 until 22 February 1945. "Pozit" refers to projectiles with proximity fuzes.

Cheers

BW
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..............Rounds fired, ........Rounds fired,
Weapon.............AAA use...........non-AAA use

90-mm...............21,032................10,891
90-mm Pozit..........3,558...................324
40-mm...............81,353................21,143
37-mm...............35,398.................2,519
.50-Cal..........2,362,272...............951,903


Rounds per weapon to bring down an enemy aircraft
Weapon..................Rounds

90-mm......................235
90-mm Pozit................178
40-mm......................333
37-mm......................590
.50-Cal.................32,360

Found the following in one of John Salt's documents. The weapon in question is the Bofors 40-mm AA Gun, which is what the U.S. used as well. Interesting how widely the quantities vary:

"WO 291/1108 Performance of the Bofors 40mm gun during operational engagements 1942–1944

This report gives figures for the "rounds per bird" found to be needed to down aircraft targets over the following periods:
Period.....................Rounds per bird
27 Mar 1942 to 30 Sep 1942..880
01 Oct 1942 to 31 Mar 1943..760
01 Apr 1943 to 06 Jun 1943..220
07 Jun 1943 to 31 Mar 1944.1320

These summary figures include all fire-control methods. Using the Stiffkey stick (sights correctional Mk IV) was found slightly superior to predictor control. Other methods are "materially less accurate". For single-engine fighters below 1000 feet in daylight, over the period 01 Apr 1943 to 6 Jun 1943, 100 rounds per bird was achieved. This was thought to represent the best possible performance for the Bofors.

There was insufficient data to determine effectiveness at night. However, the marked increase in rounds per bird in the last period was thought due to the facts that most targets engaged at night at heights over 100 feet, and that the inherently wasteful tactic of barrage fire was introduced, accounting for 50% of the ammunition expended."

thats some pretty good info I wonder why it takes more 50.cal rounds to bring down a plane than any other

I wonder why there's such a big difference between 37mm and 40mm? The shells would be almost the same size. Was the 40mm cannon markedly superior in accuracy?

Same muzzle velocity but larger shell 1.3lb against 2.06lb, slightly higher effective ceiling (500ft). The balistic charactistics of the 37mm were similar to the 50cal so accuracy is not a problem. So more than anything it's the shell weight.

The U.S. ordnance were certain from the outset that the Bofors was prefered to the 37mm Colt and it was only the Licencing of the design which held up production.

The figures can be a bit deceptive as to effectiveness. Throw up enough lead and the attacking airman might either turn back, drop his bomb(s) early and out of harms way or even if he does come in close dodging the AAA is going to harm his accuracy. It also helps the morale of troops on the ground to be able to fire at an aircraft, even if the chances of hitting anything or minimal.

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Those who live by the sword will be shot by those of us who have progressed

There was a short interesting section in Murray Peden's "A thousand shall fall" on aerial tactics versus Ack Ack fire. (Best book I've read to date.)

They would adjust speed, altitude, direction based on the information from the first salvo, then readjust based on best guestimate of the next burst and so forth and so on. These tactics were part of the training that pilots were given in the later stages of the war. Those up to early 44 apparently had to learn on the job.

__________________
Stepson of Arthur Ellison Sovereign:
RCAF Navigator: Lancasters and Wellingtons,
Bomber Command, WW2

Named after Fred Sutherland of the Dambusters.

Do any experts here have information on German proximity fuses technology in WW2? This is a subject I am quite interested in.
I can't imagine that heat seeking technology had been developed that early. I can't imagine magnets would have been effective considering how fast the shells were going...
All in all, pretty amazing technology considering the time period.

There are some links to British / US Research and Development:
Crosley's Secret War Effort: http://www.navweaps.com/index_tech/tech-075.htm
http://www.enginesofinnovation.com/h...case_study.HTM
http://en.wikipedia.org/wiki/Proximity_fuze

I have been quite impressed with the level of expertise on this forum. Hope someone can come through for me here! Tnx

Don't forget once the Allies landed on Europe, they shot down planes from both sides. That might partially account for the drastic increase of ammo expenditure.

[QUOTE=Fred Wilson;430053]Do any experts here have information on German proximity fuses technology in WW2? This is a subject I am quite interested in.

As far as I know, we hadn't any at the time. The Acht-Acht shells had time fuzes to detonate in the adjusted height combined with impact fuzes (is that the right word in English?). The 37mm and 20 mm had only impact fuzes. If they missed the target, they did no harm.

Best regards,
Obergefreiter

actually Wend the 2 and 3cm had proximity fuzes as they were fired into Allied dive bombers and if missing their target would blow themselves up at the determined range when used as ground based Fla(k)

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E ~

Those are time fuzes much like larger shells have. The fuze is set to activate a certain number of seconds after firing. A proximity fuze senses the target and activates itself at that point. Virtually all militaries and weapons using some sort of time fuze for AA fire during WW 2 had a "end of run" feature to detonate it rather than let the spent shell just return to earth and impact.

And despite that some people were still killed by the remains of "friendly" AA fire. But I believe all the large caliber AA shells (3" and above) were programmed to detonate at the estimated target height in the hope the burst would compensate for a near miss. The "end run" safety was for the smaller caliber weapons that had an insignificant burst radius. The difference with a true proximity fuse, and AFAIK the Germans never developed an effective one, is that the latter will detect a nearby target while a standard time fuse will just go bang when it reaches a pre-programmed altitude or time of flight, this lessens the requirement on weapon precision and accurately predicting the future target position at the instant of firing.
Even today small caliber shells do not have proximity fuses as the fuse would take up too much of the shell's weight making it less effective than a pre-fragmented time fuse that can have a larger warhead and so a better burst radius. In the late 1990s the cut-off was around 57mm but somebody may have made an effetive 40mm proximity round by now.