Heavy AAA: was it worth it

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Could it be argued
that the USN's lower rounds per kill ratio was facilitated by the fact that their artillery was configured and concentrated for point defence ie a ship? .
USN claimed rounds per kill for heavy flak late in the war were more like 60-240, (daylight short range-night long range) not 500 or 1500, and the number one reason was widespread use of proximity fuzes from early 1943, those low late war numbers assumed proximity fuzes. The tactical situation of shipboard AA was more favorable in that the plane had to come to the gun, but OTOH those late war targets were typically relatively small and fast a/c moving in three dimensions, not large bombers flying at constant altitude.

In 1944 British 3.7" and US Army 90mm batteries in the UK also achieved impressive rounds per kill ratio v V1's when they used proximity fuzes, also in defense of Antwerp from V1's, albeit the V-1 also flew a relatively predictable path.

However, another major element of noise in rounds per kill numbers for AA batteries is the accuracy of the claims of a/c shot down, just like air-air stats. The degree of variance between claims and reality was itself highly variable.

For example I mentioned before the value of 3" AA in defending Corregidor in early 1942, forcing the Japanese bombers to fly high, and holing them frequently per Japanese accounts. But the rounds per kill claim in that case, 500, is based on claimed downing of 50+ Japanese bombers over the campaign, and the actual Japanese losses were far fewer than that.

Joe
 
Joe, what was the real expenditure per kill in Philliphines? What was the target composition (twins, single engine, hidro...)?
 
Joe, what was the real expenditure per kill in Philliphines? What was the target composition (twins, single engine, hidro...)?
Almost all the claims by the 3" batteries on Corregidor and the other 'fortified islands' in Manila Bay were against high flying twin engine bombers, mainly Navy Type 96 ('Nell') and Type 1 (Betty), Army Type 97's (Sally) with a few missions by Type 99 Twin Engine Light Bombers (Lily). Machine guns claimed some Army Type 97 Light Bombers (Ann). In fact the larger twins often flew so high that the older powder train fuzed 3" ammo couldn't reach (27k ft max), so newer mechanical fuze ammo was sent in by submarine; this is somewhat at odds with the estimate of very low rounds per kill.

The actual losses can't be nailed precisely because mission by mission Army losses aren't known, just the totals to all causes. OTOH JNAF mission reports for those units survived so you can see the loss and damage plane by plane, and what's immediately apparent is how many a/c were hit for every one actually lost; and the Japanese official history volume for the Army's air operations in the Philippines makes the same comment, lots of planes holed for every one actually lost. I'd estimate the total outright losses to AA over those islands as perhaps <10, surely not a lot more. So the rounds per kill was at least several times what's quoted, though if 500*5=2500 that's still relatively low.

Joe
 

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