Just how good was German Flak

[ArtieBob]

The basic WWII USN fire control system was the Mk 1, which was a mechanical analog computer. Solutions were good whether the inputs were from optics or radar and the aircraft true velocity was less than 400 knots. There were several problems, optical data on angular position could be very accurate, but optical ranging, particularly with a fast moving target was not as precise. Early radars because of the wavelength and lobe dimensions was sort of the opposite, more accurate in range, less accurate for angular position. So the best inputs were to use optical angular tracking if conditions permitted and radar ranging. But even with radar ranging, the margin for error in fuse setting is great because on a 5”/38 mount the fuse is set before the round is manually loaded. On the standard 5”/38 dual mount, this is done in the shell elevator which brings the projectile up from the lower handling room. If I remember correctly, the maximum firing rate for the twin mount is something less than 20 rounds per minute, or a cycle time of about 6 seconds per gun reloading, add to this the time in the elevator and the time of flight and you will end up with a 15 to 20 second lag between the setting of the fuse and detonation. If the target is manuevering, a time error of .1second would probably render the shell ineffective. If you have ever had the chance to see the movies of kamikaze attacks during WWII, the sky is obliterated by overlapping AA bursts, yet the aircraft just keep coming. The VT fuse eliminated the timing errors. IIRC in my gunnery classes, the USN felt the effectiveness was increased by a factor of 5.

Best regards

Artie Bob (ex-second loader 5”/38 mount (lower handling room)