Koch's reliability

[k-pp]

Hi,

Just a quickie. How reliable are Horst-Adalbert Koch's technical specifications regarding muzzle velocity, weight, range and rounds per minute for German Flak guns (20mm, 37mm, 88mm, etc.)?

A cursory cross-referencing of statistics in various sources seems to give conflicting information...

Many thanks,
Karl

[Juha]

Hello
I don't have a slightest idea who Koch is but in general different ammos had different weights and different muzzle velocities. For AA guns the AP shell, German APs had usually a small burster, was usually heavier than the HE round and so had lower muzzle velocity. But then Germans had also special AP rounds with heavy penetrator casted inside light metal jacket which were lighter (was that called Composite Rigged or not in English, sorry I don't have time to check) and had higher muzzle velocity. IIRC 20mm and 37mm gun models used same ammo so, I means 20mm Flak 30 and 38 used same ammo and 37mm Flak 18, 36 and 43 used also same ammo, so their muzzle velocities with same type of ammo should be more or less same but Flak 38 and Flak 43 had higher cyclic rates than their predecessors. In automatic guns there are at lest 2 rates of fire, theoretical and practical. The latter included the time needed to change magazines when they emptied during firing. So one must check from the sources that one is comparing same facts when trying to compare the figures. On 88 the Flak 41 was a different gun than the earlier models with much higher muzzle velocity and ceiling and of course with greater range. On 88s the rate of fire depended from the crew, highly trained men in their 20s could fire faster than young schoolboys or old men working as temporary crew. And of course a crew could keep their max rate of fire only for a rather short time before geting tired but I don't know if that had any practical effect in prolonged firing or if they ran into cooling problems if they could keep 20 rpm firing rate for a long time.

[k-pp]

Thanks for the reply Juha,

Koch wrote the post-war "bible", so-to-speak, on the German Flakartillerie (Die Geschichte der deutschen Flakartillerie 1935 - 1945). It was first published in 1954 and was followed by both an extended and an abridged edition.

On page 209 of the 1954 1st edition, he lists the technical specifications of the various Flak guns. To give three of his examples:

2cm Flak-38 had a muzzle velocity of 800/990m/sec; a ceiling range of 1,070 meters and a horizontal range of 4,800 meters; rate of fire was 180/220 rounds per minute; and it weighed 410kg.

8.8cm Flak-18/36/37 had a muzzle velocity of 840m/sec; a ceiling range of 9,750 meters and a horizontal range of 14,800 meters; rate of fire was 15/20 rounds per minute; and it weighed 5,510kg.

8.8cm Flak-41 had a muzzle velocity of 1,020m/sec; a ceiling range of 14,930 meters and a horizontal range of 19,700 meters; rate of fire was 20 rounds per minute; and it weighed 8,870kg including a protective shield.

In reference to your comments, would the above stats reflect practical or theoretical results?

Or are there further variables, like the kind of ammunition used, which would again affect both practical and theoretical performance?

Best wishes,
Karl

[Juha]

Hello, they are all practical.
for 2cm Flak 38 the rate of fire is practical, one usually saw the 220 rpm in books, cyclic or theoretical was IIRC 480 rpm. One usually sees its muzzle velocity as 800 - 900m/sec or 830 m/sec for AP and 900 m/sec for HE round, maybe 990 was for AP40 Composite Rigged special AP round which was rare. I cannot remember its mv right now. Weight is right for action.
For 8,8cm earlier models 15-20 is what one normally sees in books. Around 20 rpm was possible for a good crew a while. I haven't thought that earlier but maybe 15 rpm was for 0 degree or horizontal fire because in Flak 18, 36 and 37 the breech was in ackwardly high position for loading when the barrel was horizontal. In Flak 41 it was clearly lower at that position but the gun was partly designed also for ground fire and was more or less as easy to load at 0 deg as at 90 deg, the price was more complicated carriage. Weight was around 5000kg for the older models and IIRC a bit under 8000kg for Flak 41 but that might have been without the shield, so the numbers look more or less correct to me. Muzzle velocity was IIRC for Flak 36 820 m/sec for HE and 795m/sec for AP but 840 is not far of, even the temperature of powder influence to muzzle velocity. Also the 1020m/sec for Flak 41 sounds right. Ceilings for 88s seemed to me rather teoretical. IIRC the effective ceilng for older 88s was some 8000m and for Flak 41 appr 10 000m. Without doubt the shell could fly higher but those lower ceilings are heights were there is possibility to hit something.

HTH
Juha

[k-pp]

Great! Thanks very much Juha.