From: cdb100620@aol.com (CDB100620)
Subject: WWII German flak (was stupid question)
Date: 22 Apr 1997
Newsgroups: rec.aviation.military

The Germans used three types of heavy flak:  88mm, 105mm, 128mm.
88mm comprised about 70 percent of homeland defense AAA.  Effective
altitude was about 20,000 ft.  Thus B-17s, which flew at between 23,000
and 27,000 as a general rule, were largely unaffected by the dreaded 88.
B-24s, however, flew lower and did have to contend with 88mm. (As did RAF
Bomber Command aircraft, which flew even lower than the B-24s.)
The 88mm had a spherical kill zone with a radius of about 30 ft. (roughly
113,000 cubic ft.)  When the Germans developed AAA aiming radar (the
Wurzburg A), it proved disappointing.  It could locate a bomber flying at
24,000 ft. as only being somewhere in a box 1,000 by 4,000 by 1,700 ft.
(6,000,000,000 cubic ft.)  In order to guarantee destruction of the
bomber, something like 59,000 evenly spaced 88mm shells would have to be
fired into that space.
Gen. LeMay calculated, based on some practical testing using US AAA, that
it would take 372 88mm or equivalent shells to down one bomber.  On the
basis of that calculation, he ordered 8AF bomber crews not to take evasive
action during the bomb run.  In time, 8AF policy came to be to fly
straight through any flak without taking evasive action, no matter where
along the attack route they were, the theory being that a plane was as
likely to jink into a burst as away from one, and the best thing to do was
fly a straight course and get through the flak as quickly as possible.
General der Flakartillerie a. D. von Renz estimated that in actuality it
required 4,000 88mm shells to down one bomber.
The Luftwaffe placed flak batteries in rings around cities and important
targets and in a belt along the West Wall.  The rings were 2 miles from
the target, the idea being to have the flak bursting among the bombers
just as they made their bomb runs, and disrupting their aiming.  All guns
in each battery fired at the same target at the same time.  If radar
aiming was used, the center of the bomber formation was targeted.  Up to
1943, if visual aiming was used, the lead aircraft in the formation was
aimed at.
Shells were time fuzed in the manner Erik Shilling described.  It took the
88mm shell apprx. 20 seconds to reach its maximum effective altitude of
20,000 ft., so the fuze delay was set at 20 seconds.  A Kommandogerat
optical predictor was used to determine the azimuth, slant range,
elevation and time setting.
From 1943, visual aiming was done by salvoing into a predetermined "box"
through which the bombers were predicted to pass.
Fortunately, the Germans never developed proximity fuzes, as the allies
did.  A USAAF study indicated that were the Germans  to use proximity
fuzes, 8AF flak losses would triple and the B-24 would be knocked out the
European war entirely. (Presumably, so would the low-flying RAF heavy
bombers.)  In addition, the bombers that did get through would have  to
fly at maximum height, which would  mean much less bomb accuracy.
Fortunately, this great fear was never realized.  The German boffins were
kept busy developing vengence weapons or self-cleaning gas chambers or
something.
As it was, German flak accounted for about half of all 8AF bombers lost.