I'm reading about the anti-aircraft defences Germany used to protect the Reich in the latter stages of the war. The anti aircraft shells such as the 88mm were disadvantaged by the lack of an effective proximity fuse. However, it's still surprising how ineffective they were.

Consider the US daylight raids. Wikipedia says

[the bomber combat box] stacked 750 ft (230 m) vertically, 650 ft (200 m) from front to back, and 1,170 ft (360 m) laterally. This final variation presented flak gunners with a small target, produced excellent bomb patterns, and was both easy to fly and control.

This is still a very large area in which to explode a shell, surely any half decent gun battery in daylight couldn't avoid exploding shells inside the box? Worse still in such a confined space each bomber must have been very near to the detonating shell. So it seems that either the AA fire was very inaccurate or that the aircraft were largely immune to most shrapnel.

I performed a few calculations to determine how many rounds would be required to guarantee impacting directly on an airframe by chance. The answer is surprisingly few. Assuming a 200 sq metre area for the B17, these boxes are about 7.5% opaque with airframe! Obviously, it's difficult to miss after 10 rounds. So perhaps smaller more numerous, impact fused shells, which detonate just after contact inside the frame would be more effective than shrapnel? My estimate suggests that a few hundred L70 Bofors guns equipped with such shells would be very effective against such a formation of bombers.

The nightime raids of the RAF over wider spaces would have been rather more difficult to counter since they were far more widely spread, being sometimes hundreds of miles long, however, there were perhaps other means of dealing with these.

What am I missing?

Originally Posted by perseus

I'm reading about the anti-aircraft defences Germany used to protect the Reich in the latter stages of the war. The anti aircraft shells such as the 88mm were disadvantaged by the lack of an effective proximity fuse. However, it's still surprising how ineffective they were.

Consider the US daylight raids. Wikipedia say

This is still a very large area in which to explode a shell, surely any half decent gun battery in daylight couldn't avoid exploding shells inside the box? Worse still in such a confined space each bomber must have been very near to the detonating shell. So it seems that either the AA fire was very inaccurate or that the aircraft were largely immune to most shrapnel.

I performed a few calculations to determine how many rounds would be required to guarantee impacting directly on an airframe by chance. The answer is surprisingly few. Assuming a 200 sq metre area for the B17, these boxes are about 7.5% opaque with airframe! Obviously, it's difficult to miss after 10 rounds. So perhaps smaller more numerous, impact fused shells, which detonate just after contact inside the frame would be more effective than shrapnel? My estimate suggests that a few hundred L70 Bofors guns equipped with such shells would be very effective against such a formation of bombers.

The nightime raids of the RAF over wider spaces would have been rather more difficult to counter since they were far more widely spread, being sometimes hundreds of miles long, however, there were perhaps other means of dealing with these.

What am I missing?

I don't have the statistics presently. But by far and away, the greater number of Allied bombers were downed by German fighters. "BTW: Wikipedia can be misleading at times concerning WW2 data"

If you think that the German AA fire was ineffective just look at the casualties suffered by the Allied airforce over Germany.

Originally Posted by LeEnfield

If you think that the German AA fire was ineffective just look at the casualties suffered by the Allied airforce over Germany.

yeah, I'm thinking more B-17/B-24s were downed by A-A than by fighters.

A total of ~ 150,000 allied airmen died in the European theater of WW2. Roughly 1/2 American and 1/2 Common Wealth. The greater part of these were bombers B-19's, Lancaster's and such.
I still hold that the greater % were downed by German war planes than by AA fire. This is the reason the losses of bombers went down considerably in the spring of 44 when the P-51 Mustangs could accompany the bombers anyplace in Germany. They were able to engage the German fighters and greatly reduce the treat since they were built in such large quantities to fly the full distance and with the exception of the ME-262 could out dogfight the German fighters for the most part (depending on the pilot).

Unfortunately the truth is less glorious. Safety and pilot training was obviously compromised in war relative to peacetime, and a large number of losses were accidents, sometimes even before they were delivered!

According to the AAF Statistical Digest, in less than four years (December 1941- August 1945), the US Army Air Forces lost 14,903 pilots, aircrew and assorted personnel plus 13,873 airplanes — inside the continental United States. They were the result of 52,651 aircraft accidents (6,039 involving fatalities) in 45 months.

Think about those numbers. They average 1,170 aircraft accidents per month—- nearly 40 a day. (Less than one accident in four resulted in totaled aircraft, however.)

It gets worse…..

Almost 1,000 Army planes disappeared en route from the US to foreign climes. But an eye-watering 43,581 aircraft were lost overseas including 22,948 on combat missions (18,418 against the Western Axis) and 20,633 attributed to non-combat causes overseas.

http://www.wwiifoundation.org/missio...ircraft-facts/

The Germans suffered even more through five long years of pilot attrition, the final straw were the escorts of the US 8th in the spring and summer of 1944. The US aircraft were good but the US were also able to draw upon fresh young men for this prestigious task. The Luftwaffe were left with very few half decent pilots [ame="https://www.youtube.com/watch?v=b4EASQJ0vJk"]to fly the ME 262[/ame] which was being produced in large numbers in the latter stages of the war. Together with the infrastructure damage and fuel shortage problems it made limited impact.

Some more interesting stats here, each of the major combatant countries had an almost identical number of combat aircraft losses, except for Germany which was only 30% greater. However, the US had the greatest losses in aircrew due to the number of crew in the bombers no doubt!

Regarding my contention that German AA was not very effective. I mean far less effective than you would think based on the area covered by aircraft in those compact combat boxes.

American bombers had losses down to 1% per mission once the Luftwaffe (but not the flak) had vanished. Problem is, even small losses per mission mount up over time resulting in the high figures mentioned in my previous post.

My point exactly, basically due to P-51 coverage. Once the Luftwaffe fighters were shot down or destroyed otherwise, allied bombing losses went down dramatically.

As for casualties, yes many occur that are not directly a result of combat or as you say "not as glorious". Let me remind you everyone of those men that died was an allied veteran and whether he died in training or as a result of an accident it is no less glorious then that of the men who gave his life for his country fighting.

The USA suffered ~ 300,000 combats deaths in WW2, yet lost ~ 500,000 men in WW2. The x-tra ~ 200,000 died as a result of accidents, disease, friendly fire, exposure, even snakebite in Asia, "the list goes on". All ~ 500,000 of these men gave their life for their country.

I´ve read somewhere that it took more than 3,000 88-mm shells to shoot down a bomber.

Originally Posted by Kesse81

I´ve read somewhere that it took more than 3,000 88-mm shells to shoot down a bomber.

Indeed

One Luftwaffe study estimated it took over 3,300 88-mm shells to successfully shoot down a bomber.

http://histclo.com/essay/war/ww2/air...c/gd/flak.html

whilst this might not sound impressive the Germans produced something like 25,000 heavy Flak guns.