Safe from Aerial Attach at what depth?

[SAJ]

I have a pretty straight forward question I think anyway. At what depth would a U boat commander think that he would be safe from an Aerial Attach from a US or British bomber? I am sure that a aerial attack from a bomber would be deadly if a U boat were to be caught at periscope depth but could an aerial bomb penetrate the surface of the ocean to a depth of say 50 or even 100 meters and damage or destroy an U boat??

Is there any know record of a U boat being sunk by a bomber while at depth?

[ROLAND1369]

The question is not whether depth charges or bombs could destroy a deeply submerged submarine, surface vessels were doing that already. The problem was detecting and more importantly prosecuting an attack on a deeply running submarine. Aircraft at best were normally equipped with ASR radar which could only detect a surfaced submarine or snorkel. Even the limited use of Sonobouys or Magnetic Anomaly Detectors could at best do shallow water detection. In addition the bombers of the period use bombs with fixed fuze settings prior to takeoff and the aircraft usually had shallow settings on both bombs and depth charges. An additional problem was that aerial Ordinance both depth charges and bombs were relatively thin cased and would be crushed at deep depths.

[SAJ]

Thanks but that was not what I was after. I found out off another website that if being bombed from the air if a U boat managed to make it below 50 meters or so they were generally safe because bombs dropped from altitude would generally explode before the 50 meter mark.

[Polar bear]

hi,

an aerial bomb might not have been able to go that deep, but a Mk 24 mine "Fido" acoustic homing torpedo was the more dangerous weapon from May, 1943, onwards. It had a search pattern at first 50, than 150 ft (= 45 m) and if it had locked onto a u-boat's propeller noise, it followed even deeper.

greetings, the pb

[T. A. Gardner]

To be "safe" once submerged, the sub had to go deep enough that for the light and sea conditions it couldn't be observed from the air submerged. Under the right conditions, a submarine might be seen submerged as deep as 100 feet, possibly more. The US conducted camouflage experiments to come up with a paint scheme that would reduce this possibility.



The German U-boat camouflage scheme worked well when surfaced but actually works against the boat submerged. That's the first problem.

The second is the US and Britain starting in 1943 introduced sonobouys that could be dropped from aircraft.

http://www.navairdevcen.org/PDF/THE%20E ... NOBUOY.pdf

This meant an aircraft could conduct a passive sonar search for a submerged sub. To improve their use, explosives could be dropped to induce a "ping" that the sonobouys could pick up (Judy Search was the code name). Once the sub was located, the plane could depth charge it. Of course, it did depend on the plane's depth charge depth settings as these were usually set before take off and couldn't be changed.
The US introduced the "retro bomb," basically a hedgehog rocket that could be fired from the plane at a submarine surfaced or submerged. These had contact fuzes so depth didn't matter.

So, the only real defense a sub has versus a airplane in WW 2 was dive and dive deep right off. That renders the submarine useless for all intents.