Medium bombers: Flak magnets?

[gjs238]

Were lower flying medium bombers like the B-25, B-26, etc more succeptable to flak than the higher flying heavies?

 

[syscom3]

The types of targets the medium bombers went after were defended by fewer heavy flak weapons. And since they came in lower (medium altitudes) and at a faster speed, the numbers of salvo's the heavy flak batteries could fire were limited.

Over all, the medium bombers suffered fewer loss's from flak than the heavy bombers.

 

[TheMustangRider]

The B-26 comes to mind, an initially maligned bomber that finished its service career in WWII with one of the lowest loss ratio in the ETO and MTO.

 

[tomo pauk]

The types of targets the medium bombers went after were defended by fewer heavy flak weapons. And since they came in lower (medium altitudes) and at a faster speed, the numbers of salvo's the heavy flak batteries could fire were limited.

If one flies under 20000 ft, the typical 3-4in AAA has far more chances to achieve a hit, and/or to make a better judgement at what time to set the fuse, than it would be a chance for the target going above 25000 ft. Under 10000 ft, the plane is both under attention of medium AAA and 37-40mm AAA. Under 3000 ft, he is likely to be shoot at by 20-40mm AAA, so it hardly matters now that the medium AAA is avoided. Only if planes fly at tree top, the defender has poor chance to hit something.

Over all, the medium bombers suffered fewer loss's from flak than the heavy bombers.

Was that really so?

 

[wuzak]

If one flies under 20000 ft, the typical 3-4in AAA has far more chances to achieve a hit, and/or to make a better judgement at what time to set the fuse, than it would be a chance for the target going above 25000 ft. Under 10000 ft, the plane is both under attention of medium AAA and 37-40mm AAA. Under 3000 ft, he is likely to be shoot at by 20-40mm AAA, so it hardly matters now that the medium AAA is avoided. Only if planes fly at tree top, the defender has poor chance to hit something.

I think attacking at treetop height was the best method for the Mosquito. They had the added advantage of not having a very large speed deficit, if at all, to the defenders at that height. Not so sure about B-26s, B-25, etc.

Was that really so?

Yes, that really was so, in the ETO. Even lower than the Mosquito, in fact.

But you would have to look at the targets they were used for, the depth of the raids and the opposition. IIRC B-26s rarely went on deep penetration raids, and rarely went beyond fighter escort range (in the ETO).

 

[VBF-13]

Could anti-aircraft flack down an aircraft without actually hitting it? I've always wondered at that.

 

[TheMustangRider]

Could anti-aircraft flack down an aircraft without actually hitting it? I've always wondered at that.

It could have been possible by causing a stricken a/c to collide with another one.
Proximity Fuze flak would have been lethal for Allied bombers had Germany perfected the concept before war's end.

 

[tyrodtom]

Most of the bombers brought down by flak at altitude, weren't actually hit by the shell, it just exploded close enought to damage the aircraft/crew.
When a AA shell actually did explode inside the aircraft, it would be instant disintergration. Just one passing thru a wing, would likely knock the wing off.
I'm talking about the flax heavy bombers were usually encountering, 88mm and up.

 

[Shortround6]

The 75mm and up AA shells used time fuses to explode the shell at the calculated altitude of the bombers. Most countries used a rather complex "calculator/directer/predictor" that was actually and rather sophisticated analog computer to help aim the guns and calculate the fuse settings. Many guns had automatic fuse setters on the gun mounts that were driven by signals from the central predictor/directer. Bigger shells had a bigger blast radius and put more fragments into the air. Times of flight for the shells could be in the 20-30 second range which introduced fuse errors.

 

[tomo pauk]

...

Yes, that really was so, in the ETO. Even lower than the Mosquito, in fact.

But you would have to look at the targets they were used for, the depth of the raids and the opposition. IIRC B-26s rarely went on deep penetration raids, and rarely went beyond fighter escort range (in the ETO).

My point exactly (the bolded part) - one need to compare the missions of the bombers, and then to draw conclusions.

 

[Thorlifter]

Bigger shells had a bigger blast radius and put more fragments into the air. .

I have always thought about fighter planes dog fighting and the amount for bullets they shot and missed and how they just sprayed the ground. But I think this is the first time I ever really thought about the amount of flak fragments that just had to pepper an area with potentially lethal "rain". It just adds to the horror of war in my mind.

 

[davebender]

Were lower flying medium bombers like the B-25, B-26, etc more succeptable to flak than the higher flying heavies?

Of course.

Greater exposure to AA fire (especially medium flak) is a price you must pay for decent accuracy with iron bombs. That's why the Ju-88A and Me-410A placed the crew in an armored cocoon to protect them against ground fire. Light bombers of other nations such as the Soviet IL2 also had significant armor protection.

 

[VBF-13]

I can understand how the flack fragments can cause damage short of a direct hit. What about just the concussions from the blasts? I'm thinking of submarines shaken up by depth charges. I'd imagine the concussions were at least disruptive.

 

[davebender]

Medium / light bombers should be operating below 15,000 feet. I think weapons 25mm to 40mm in size would be a much greater danger then the heavy stuff.

 

[Shortround6]

Medium / light bombers should be operating below 15,000 feet. I think weapons 25mm to 40mm in size would be a much greater danger then the heavy stuff.

25mm to 40mm were useless at 15,000ft. They were pretty much useless at 12,000ft. A lot depended on the fuses (time to self destruct) and on the sighting equipment of the guns, which was usually more primitive (in some cases much more primitive) that the sighting equipment/fire control of the larger guns. The better fire control of the bigger guns required tracking the target for a number of seconds before coming up with a solution so it was rather useless on fleeting targets.

 

[davebender]

Light bombers typically began their dives from 12,000 to 15,000 feet. Bomb release would occur within a minute after beginning the attack run.

3.7 cm Flak 18/36/37/43 - Wikipedia, the free encyclopedia
German 3.7cm flak effective range was supposedly 4,800 meters. So an enemy bomber would be under fire for the entire attack run. Accuracy won't be great at 15,000 feet but that's why these size weapons spit out over 200 rpm. A single 37mm or 40mm shell will serious damage any light bomber so you only need one hit.

 

[Jabberwocky]

Light bombers typically began their dives from 12,000 to 15,000 feet. Bomb release would occur within a minute after beginning the attack run.

3.7 cm Flak 18/36/37/43 - Wikipedia, the free encyclopedia
German 3.7cm flak effective range was supposedly 4,800 meters. So an enemy bomber would be under fire for the entire attack run. Accuracy won't be great at 15,000 feet but that's why these size weapons spit out over 200 rpm. A single 37mm or 40mm shell will serious damage any light bomber so you only need one hit.

US and UK considered the German 3.7 cm flak weapons to have an practical/accurate ceiling of about 5,000-7500 ft. The 5 cm flak was considered to have a practical ceiling of about 10,000 ft, roughly the same as the 40 mm Bofors.

The 4,800 m "effective" range for the 3.7 cm flak weapons is actually just the height at which the tracer burned out (when fired at 85 degrees) and the round self-destructed.

From an October 1943 assesment of German flak:

The 37-mm has a maximum horizontal range of 8,750 yards, and would have a maximum vertical range of 15,600 feet, except that the 14-second tracer ammunition self-destroys at about 13,800 feet. With 7-second tracer, the shells self-destroy at about 9,200 feet. As with the 20-mm the effective ceiling for accurate engagement is less than these figures, being about 5,000 feet. The theoretical rate of fire of the 37-mm weapon is 150 rounds per minute, which reduces in practice to about 60 rounds per minute for cartridges loaded in clips of 6 rounds each. High explosive shells of both the 20-mm and the 37-mm have an instantaneous percussion fuze which functions on impact.

The usual fire control equipment for German light automatic weapons is a gunsight with a computer mechanism on the course and speed principle, together with a separate stereoscopic range finder. Other sights are used in which the necessary deflections in azimuth and elevation are automatically calculated by an electric control mechanism that operates when the traversing wheels are moved. Forward area sights are attached for firing at very close range when a high rate of traverse of the weapon is necessary.

The fire is corrected by visual observation of the paths of the tracers. The fact that such observation is correct only for the earlier and flatter portion of the trajectory accounts for the previously mentioned reduced figures for "effective" range. Beyond the "effective" ranges, the probability of a hit drops off rapidly

 

[Shortround6]

Thank you, I would note that even at a 7 second time of flight for the shell a 300mph airplane will cover 3080ft or over 1/2 mile which makes range estimation/finding, course prediction and speed estimation/measurement rather critical and rather beyond the ability of many light AA batteries unless provided with radar fire control (not just radar warning) and a director system.

 

[tomo pauk]

A video (two, actually) made for the bomber crews of the USAAF:


View: https://www.youtube.com/watch?v=PIYVwqHM488

 

[davebender]

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?