Medium bombers: Flak magnets?

davebender said:

During 7 seconds a heavy AA gun will fire 1 or 2 shells. During that same 7 seconds a typical twin 37mm or 40mm will fire 40 shells. Which weapon has the best chance to disrupt an enemy bomb run at altitudes below 15,000 feet?

Click to expand...

The one that comes closest and puts the pilot off, 40 rounds wide of the mark will have less effect then one big one exploding close by.

davebender said:

During 7 seconds a heavy AA gun will fire 1 or 2 shells. During that same 7 seconds a typical twin 37mm or 40mm will fire 40 shells. Which weapon has the best chance to disrupt an enemy bomb run at altitudes below 15,000 feet?

Click to expand...

Depends on height. Even at 12,000ft the 37mm and 40mm guns are pretty much useless.

And lots of luck getting 40 rounds out of a twin Bofors 40mm in 7 seconds.

davebender said:

During 7 seconds a heavy AA gun will fire 1 or 2 shells. During that same 7 seconds a typical twin 37mm or 40mm will fire 40 shells.

Click to expand...

The twin 37 mm had 8 round clips as standard. To fire 40 shells, it has to reload twice.

The practical rate of fire for a twin Flak 43 was about 240-300 rpm. So, in seven seconds its going to fire about 28-35 shells.

The German 88 Flak 36 has a practical RoF of about 15-20 rpm. So, in seven seconds it'll probably get 2, maybe three shots off.

Which weapon has the best chance to disrupt an enemy bomb run at altitudes below 15,000 feet?

Click to expand...

If the bombers are above about 10,000 ft, I'd say that clearly the medium/heavy AAA is your best bet. Below about 8,000 ft, the light AAA is better.

A better solution than either is something like the 5 cm flak, which was effective up to about 10-11,000 ft, although that weapon had enough faults that it may be considered a failure.

Jabberwocky said:

. A better solution than either is something like the 5 cm flak, which was effective up to about 10-11,000 ft, although that weapon had enough faults that it may be considered a failure.

Click to expand...

True but shows there was a gap between the 37-40mm effective altitude and the minimum effective altitude of the 75-88mm guns, which is why the Germans spent so much time and effort on a 50-55mm AA gun.

The training film, from post #19 here, declines that such a possibility exists, ie. there was no such thing as safe altitude between the max altitude of 37-40mm AAA and minimum altitude of 88mm.

gap between the 37-40mm effective altitude and the minimum effective altitude of the 75-88mm guns, which is why the Germans spent so much time and effort on a 50-55mm AA gun.

Click to expand...

Post war Soviet Union developed 57mm flak. Perhaps the German 50mm weapon was on the right track.

davebender said:

Post war Soviet Union developed 57mm flak. Perhaps the German 50mm weapon was on the right track.

Click to expand...

German 55mm AA gun influenced strongly to Soviet 57mm design.

Juha

There were several 5 cm and 5.5 cm Flak projects, but none of them really came to fruitiion. The Gerat 58 formed the basis for the post-war Soviet S-60 57 mm gun, which was very successful.

The German 5.5 cm flak was reckoned to have an effective range of about 13,000 ft with visual aiming, about 20,000 when radar controlled. The weapon was very powerful, with a M/V of just over 1000 m/sec (compared to around 800 m/sec for the 37 mm flak and 880 m/sec for the Bofors). The major drawback was the lower rate of fire. With the five round clips used (which weighed over 30 kg each), the gun fired at about 60-70 rpm.

Gotta consider that the overwhelming majority of german Heavy flak consisted of 88mm guns. These had an effective ceiling, when the gun was new of about 25000 feet. However, by 1944, many of these guns were badly worn, and the German inspector of Flak was complaining that effective ceilings for these guns was by late '44 as low as 21000 feet. This greatly reduced the firing times that could be applied to various bombers. The median operating altitude of a Lancaster was about 19000 feet. With an effective ceiling of just 21000 freet, the firing window for the flak was very restricted, and they had to be in the right place to a far tighter tolerance.

For the US Heavy Bombers at the end of the war, the B-17s had a median operating altitude of 26000 feet, whilst the b-24s had a median operating altitude of about 24000 feet. This explains a lot as to why the US bombers at the end of the war were not as badly affected as they had been in 1942-3. A good surrogate measure of the decreasing effectiveness of the flak arm are its ropunds per kill statisitics. In 1942-3 the germans are estimated to have been expending about 4000 rpk. by late 1944, this figure had absolutely blown out to over 16000 rpk. Not all of that is related to the falling effective ceilings of the gun park....decreased training levels of the gun crews, greater dispersal of the defences, allied ecm countermeasures all played a part in this as well.

Unfortunately, I do not have figures on the median operating altitudes of the US Mediu Bombers, notr can i differentiate between RAF and US forces

Worn artillery was normally sent back to the factory for rebuild. However that probably didn't happen during the final six months of the war as the German economy fell apart.

Thats an understatement. another good suurogate measure is the number of barrle failures of the heavy guns. The park expanded from about 8000 guns to about 12000 in the period 1943-4. In that same period, catastrophic gun failures skyrocteded from around 30 per month to a whopping 320 by august 1944.

Again, not all of this was due to worn out guns, but they had to be a significant factor. some of the problems related to falling quality control of the ammunition, some related to the relative inexperience of the ersatz gun crews now manning most of the batteries. Some also was due to the quadrupled (or thereabouts) ammunition expenditures. But some, as the flak artilleries inspector general points out, was due to the clapped out nature of many of the guns that were retained long past their service life.

Moreover, your explanation suggests an orderly and timely refurbishment of the gun park. That would be contrary to most German programs. They tended to "put everything in the shop window" and not worry enough about spare parts as much as they should have. Witness, the catastrophic failures of the panzer arm on the eastern front 1941-2. Down to about 10% effective runners by 5 December, because engines and transmissions for the tankls were in such short supply.

In any event, guns after a while simply cannot be refurbished. they suffer metal fatigue in the carriages and the cradles that simply cannot be repaired. Many of the German guns were suffering from that problem by 1944.