Flak vs fighters

While browsing in a local library some time back, I came across one of those generic WW2 books that give some broad info with lots of pictures. One thing that caught my eye was in the "Bomber Offensive" chapter, which stated that the bomber crews feared the German flak more than the fighters. They were referring to the daylight raids undertaken by B17's and B24's, although the RAF night sorties were probably included as well. Does anyone have any accurate info around this subject? Obviously no amount of fighter escort could protect a bomber from flak, and the German 88mm was an effective weapon; but do records exist as to what percentage were downed by flak? No doubt there are claims and counterclaims from both sides, but I have wondered about that statement ever since reading it.

"Army Air Forces Statistical Digest, World War II" has the information you are looking for. For the ETO, begin at table 159.
The digest is available in PDF format here:
http://www.afhra.af.mil/timelines/

Its also on the ibiblio site
Army Air Forces Statistical Digest - World War II

To get an idea look at a few select statistics during the war.

Between January and April 1941 Flak accounted for 79% of the 144 aircraft downed in the West (including Norway). In the last six months of 1941 Flak in the Reich accounted for 647 aircraft, including 242 at night. To put this in perspective, Luftwaffe night fighters accounted for 421 aircraft in all of 1941 . A further 1,325 aircraft were shot down by Flak, mostly in the East, in the last three months of the year alone.

A Bomber Command ORS conducted research into aircrew casualties between April and November 1942. 95 casualties returned wounded by Flak, 105 by fighters BUT the ORS pointed out that an aircraft damaged by Flak was much more likely to fall prey to fighters.
In the second half of 1942 the RAF lost 169 aircraft to fighters and 193 to Flak.

It wasn't until early 1944 that RAF losses to fighters exceeded those caused by Flak. For the entire war Flak accounted for 41% of Bomber Commands losses, night fighters for the rest.

Between June and August 1944 the US 8thAF lost 341 aircraft to flak with a staggering 10,972 damaged. For the 15th AF these figures are 313 and 3,357 respectively. 31% of 8th AF losses to all causes were caused by Flak. For the 15th AF this was 44% (of heavy bombers).
If you break down the figures for the Mediterranean Allied Air Forces (MAAF) you find that for all aircraft types in the last year of the war the flak outscored the fighters at a rate of 2.6 to 1.

Flak accounted for about 50% of all US losses of heavy bombers and nearly 26,000 8th AF bombers were damaged. Of aircraft damaged by flak 27% were deemed "serious".

Aircrews, particularly the Americans operating in daylight did indeed fear the flak. It drove bombers higher and made bombing much less accurate. General Lemay complained that due to violent evasive manoeuvring on the bomb run the 8th AF was "throwing bombs every which way." This, he maintained, was reducing the 'accuracy' of area bombing.

In March 1945 General Spaatz rated flak "the biggest factor affecting bombing accuracy.

A post war USAAF study concluded that 39.7% of US radial bombing error was due to nerves, evasive action and reduced efficiency due to flak. A further 21.7% of the error was attributed to increased bombing altitudes in an attempt to evade flak. In other words the flak directly caused over 60% of the bombing's inaccuracy.

Cheers

Steve

Steve, maybe it would be good to state a number of AAA (both heavy and light) and fighters at respective war theaters?
Eg. how many night fighters were used to kill 421 bomber in all of 1941, how many of those were with radar, and how many AAA the Germans employed in the West to achieve 242 night kills in the second part of 1941?

Steve - Lemay did indeed note that pilots were taking evasive action which ruined good bombing, the AFE stsyem installed in the B-17F and G starting in early 1943 took all flight maneuver out of pilots hands and slaved the bomb run to the bombardier and Norden bombsight - then he devised combat box formation and put in the 'lead crew' system in which the best bombardiers and navigators were in the a/c leading each squadron.

End of bomb run maneuvering and beginning of much better results, given ability of bombardier to see the target.

Hans Westermann provides the best Statistical Analysis of German flak during the war. according to him, fighters were slightly more efficient at shooting down aircraft. but Flak was more cost effective.

Flying high makes a big difference to WWII AA gunnery. According to Wstermann, in 1944 the average numbers of Heavy Flak ro0unds required per Kill was around 16000 shells. This is not really representative however. In 1941-2 the average expenditure was around 4000. Some of the things that changed was a switch away from deicated well trained crews, the effects of window and other ECM measures that all but removed German gunlaying radars as effective, the worn out nature of the German gunpark by 1944, the sheer explosion of flak batteries which meant they tended to just shoot at anything even if the chances of a hit were almost zero. By 1944, German flak was reduced to relying on barrage fire, which greatly reduced its effctiveness.

But returning to the altitude issue, a USN study conducted in 1944 for rounds per kill in the PTO, against mostly low flying aircraft, determined the average ammunition expenditure was around 2500 rpk. This was a study in 1944, after VT fuses, and efficient fire control systems had been universally adopted. The main LAA weapon by 1944 was the 40mm although numerically the 20mm was still more prevalent. 20mm ammunition expenditure for the USN was decreasing, whereas 40mm ammunition expenditure was increasing.

Despite the numerous differnces between the ETO and PTO, i believe a big factor in the lower RPK in the Pacific was because the targets were mostly under 10K altitude.

That holds true only if the fighters are escorting bomber aircraft as bombers were the priority flak target.

I suspect A-36s and P-47s assigned to CAS missions were every bit as afraid of flak as B-17s. Perhaps even worse as flak is a lot more accurate at lower (i.e. CAS) altitudes.

parsifal said:

Hans Westermann provides the best Statistical Analysis of German flak during the war. according to him, fighters were slightly more efficient at shooting down aircraft. but Flak was more cost effective.

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Does Mr. Westermann say just how much the Flak was more cost effective?

Flying high makes a big difference to WWII AA gunnery. According to Wstermann, in 1944 the average numbers of Heavy Flak ro0unds required per Kill was around 1600 shells. This is not really representative however. In 1941-2 the average expenditure was around 4000. Some of the things that changed was a switch away from deicated well trained crews, the effects of window and other ECM measures that all but removed German gunlaying radars as effective, the worn out nature of the German gunpark by 1944, the sheer explosion of flak batteries which meant they tended to just shoot at anything even if the chances of a hit were almost zero. By 1944, German flak was reduced to relying on barrage fire, which greatly reduced its effctiveness.

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IIRC, the numbers in 1942 were 2000 rounds per kill for heavy pieces, increasing to 4000 in 1944, due to barrel wear, more efficient Allied ECM, ever worse quality of crews?

Does Mr. Westermann say just how much the Flak was more cost effective?

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Yes, he doesd, based on the amount of money poured into the fighter arm, versus the amount pured into the flak arm

IIRC, the numbers in 1942 were 2000 rounds per kill for heavy pieces, increasing to 4000 in 1944, due to barrel wear, more efficient Allied ECM, ever worse quality of crews?

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Nope, incorrect. The figures are 4000 in 1942 and 16000 in 1944

parsifal said:

Yes, he doesd, based on the amount of money poured into the fighter arm, versus the amount pured into the flak arm

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Okay. I'm tempted to actually print his papers, in order to read them more comfortably.

Nope, incorrect. The figures are 4000 in 1942 and 16000 in 1944

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Ah - would that mean that figure '1600' in the post #6 here actually means '16000'?
Spending 4000 x ~10 kg of material (= 40 metric tons) to kill a 3 or 7 ton aircraft in 1942, or 160 metric tons in 1944. Or maybe more in 1944, since the 10.5 and 12.8 cm cannons were introduced?

Ill have a closer look tonite and see if I can get some figures on costs.

Depending on who you read and believe, LW aircraft losses were somewhere between 75 and 110000. thats a lot osf aircraft lost , and a big proportion of these losses were fighters. The Germans expended a lot of ammuhnition, and lost a lot of aircraft. They also built a lot of airfields and spent a lot of R&D on radar and aircraft development, as well as train aircrew. It costs a lot to have an effective air defence system.

Bear in mind that the flack being more cost effective than fighters on a kills per buck basis doesn't make it a universally better option. Flack has a number of advantages compared to fighters – it is cheaper, far less vulnerable and the crews are quicker and easier to train – but it also has disadvantages, primarily that it is static. The only time you can be sure the attacking bombers will be over your flack battery is when they are about to bomb their target. You can't uproot and relocate your battery to attack bombers that have taken a different path or attack a different target to the one you have anticipated – for that kind of flexibility you need fighters. The two are complementary.

Thanks for all the great info everyone; It gives me a much more balanced perspective. I did not consider the effects on bombing accuracy when I first asked the question, so that was an added bonus.

Impacts on accuracy are in fact the major contribution of flak. Forcing planes to fly high in itself reduces accuracy of iron bombs significantly, but being shot at also makes the crews make erros on the bomb runs

Excellent stats, great discussion. I have spoken with a few 8th and 15th AF bomber crewmen and they all universally despise and fear flak more than fighters. Most said it was not being able to shoot back like you could at an attacking fighter.

Frag

Not all planes were equally vulnerable, the Stirling was much more likely to get hit than a Halifax or Lanc because of its low ceiling. I believe that it created some conundrums with Pilots. The Halifax was easier to escape from than a lanc but a lanc was less likely to be shot down. A fortress was better at saving its crew but a liberator was less likely to be hit in the first place. As with all things the situation changed during the conflict. Use of radar guided guns use of window use of the bomber stream to overwhelm defences shifted the advantage one way or another.

Not exactly piloted aircraft but this shows how technology could change the game.

The development of the proximity fuze and of centimetric, 3 gigahertz frequency gun-laying radars based on the cavity magnetron helped to counter the V-1's high speed and small size. In 1944, Bell Labs started delivery of an anti-aircraft predictor fire-control system based on an analog computer, just in time for the Allied invasion of Europe.
These electronic aids arrived in quantity from June 1944, just as the guns reached their firing positions on the coast. Seventeen percent of all flying bombs entering the coastal 'gun belt' were destroyed by guns in their first week on the coast. This rose to 60% by 23 August and 74% in the last week of the month, when on one day 82% were shot down. The rate improved from one V-1 destroyed for every 2,500 shells fired initially, to one for every 100. This still did not end the threat. V-1 attacks continued until all launch sites were captured by ground forces.

To return to the original 'flak vs fighters' theme, here is page 1 of a 270 page (there's a clue in the size of it) document entitled "Light, Intense and Accurate - US Eighth A.F. Strategic Fighters versus German Flak in the ETO."



Point #2 makes it quite clear how the 8th A.F. perceived the threat of flak and the document backs this up with a lot of statistics whilst also devoting pages to how the Allied Air Forces in Europe minimised their losses to this most dangerous of weapons.

Cheers

Steve

Light flak was a true menace for lower flying aircraft, from ww2 until today.
Download site for that document: link.