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The loss of U 761 - 24th February 1944 - M.A.D and Retro Bombs

Discussion in 'Submarines and ASW Technology' started by Liberator, Feb 10, 2015.

  1. Liberator

    Liberator Ace

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    THE SINKING OF THE TYPE VIIC SUBMARINE U 761 (Oblt. Horst Geider) IN THE STRAIT OF GIBRALTAR ON THURSDAY THE 24TH FEBRUARY, 1944.

    202 Squadron
    Catalina 'G'

    Crew.
    F/L. J Finch
    F/O. B J. Goodhew
    F/S. L. Radcliffe
    F/S. A D S. Sugden
    F/S. A P. Newman
    F/O. R K. Bell
    F/S. A. Lowe
    Sgt. E. Wass
    W/O. A W. Martin

    PBY Catalina No.15 VP 63 Squadron

    PBY Catalina No.14 VP 63 Squadron

    The sinking of this U-Boat is thought to have been the first achieved as a result of detection by aircraft fitted with Magnetic Airborne Detector device (M.A.D.)

    On the afternoon of the 24th February, 1944, H.M. Ships " Anthony," " Wishart " and " Wither­ington," together with M.A.D. fitted Catalina aircraft were patrolling to the westward of Gibraltar. At 1558 one of the Catalinas obtained contact and smoke floats were dropped between " Anthony " and " Wishart." The former closed and made contact by asdic ; she did not, however, attack but crossed the target, thereby causing the aircraft to lose their M.A.D. contact. " Anthony " prepared to attack but found herself fouled by " Wishart " who had also closed and the asdic contact was then lost.

    The ships and aircraft' began a search. After about an hour the Catalinas regained contact. " Anthony " closed the smoke floats which they dropped and established asdic contact but on the aircraft reporting that they were about to attack, she altered course to port and reduced speed to 7 knots in order to minimize the interference caused by her wake through which contact was, in fact, held. The Catalinas made three attacks with Retro-bombs.

    " Anthony " attacked herself at 1701 and with a ten-charge pattern brought the U-Boat to the surface, more or less out of control. As she began to submerge " Wishart " attacked with another ten-charge pattern and at 1712 " Anthony " dropped a third ten-charge pattern set shallow.

    .Tbe U-Boat again came to the surface, this time too damaged to continue the fight. Under fire from the ships and attacked by U.S.N. Ventura aircraft and Catalina G/202, her crew abandoned her. She sank within a few minutes. 9 crew died and 41 survived.

    http://www.uboatarch...Photographs.htm


    An explanation of M.A.D. AND RETRO-BOMBS

    M.A.D

    Magnetic Airborne Detector
    This is a device installed in aircraft for the purpose of locating submerged submarines by detecting the small local changes produced by submarines in the magnetic field of the earth. It is in fact a form of flying Indicator loop. The normal range of detection (aircraft to target) varies from 400 to 700 ft. That is to say, an aircraft patrolling at 100 ft. should theoretically be able to detect a U-Boat 300 ft. below the surface. It will also detect wrecks or other fairly large iron or steel objects.
    The equipment includes a recorder which produces a continuous trace on a moving tape and magnetic oscillation appears as a distortion in the trace.
    M.A.D. equipment (the weight of a typical installation is about 135 lbs.) has been installed and is in operational use in some United States Catalinas, and tests are being made in other types of aircraft. (As of March 1944)

    Retro-Bombs

    To increase the effectiveness of M.A.D. it has been necessary to develop a weapon which can be released at the moment a strong signal is received, and in order to ensure that the weapon will hit the water above the target a rocket-propelled bomb is projected backwards with a speed equal to the forward speed of the aircraft so that the backward motion of the missile will neutralize the forward speed of the aircraft. There are two variations of this‑

    (i) by giving the bomb excess backward velocity, or

    (ii) by giving it a downward component of velocity so as to reduce the time of fall.

    This weapon is known as the Retro-Bomb which is similar to the Hedgehog projectile in size and weight, but has a rocket motor attached. The bombs have contact fuses.

    M.A.D. Tactics

    M.A.D. is probably mostly of value as a means of tracking a U-Boat whose presence is already known or in narrow waters such as the Strait of Gibraltar. Here, on 16th March a very promising attack was made on a U-Boat by surface ships after initial detection and attack by M.A.D. equipped Catalinas of the U.S.N.

    In tracking a submerged U-Boat the M.A.D. equipped aircraft flies over the area in circles com­pleting two circles on each side of the probable course of the U-Boat, and dropping a marker during each circle when a signal is received. Towards the completion of the fourth circle, the aircraft will prepare to carry out its bombing run between the lane of markers. The Retro bombs are launched either manually or automatically when the M.A.D. signal is received.



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  2. lwd

    lwd Ace

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    Interesting. I've always seen MAD as being an acronym for Magnetic anomaly detector though. I hadn't realized just how early they went into service for the allies.
     
  3. denny

    denny Member

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    Man...that is some world class info.
    Electronics was really progressing by leaps and bounds circa 1940-1945.
    Never ceases to amaze me what the science community was hip to "back then".
    Fascinating post btw.
    Thank You
     
  4. Takao

    Takao Ace

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  5. lwd

    lwd Ace

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    Thanks, I wondered if something like that was the case. Especially since it wasn't adopted to surface vessels during the war.
     

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