RE: Mk24 and Cutie Performance
Posted by: Don Baker ()
Date: September 27, 2000 08:29PM
This is a follow-up to your comments on the performance of â€œCutieâ€ (MK24 modified for submarine launch). In particular I was interested in your comments regarding the performance of Cutie against surface ships in shallow water and the deleterious effect of wave noise and bottom reflected signals on the torpedoes performance. It occurred to me that most of the Mk24 development testing was conducted in Gardiners Bay, Long Island Sound in water depth of approximately 75 feet. Surface ship traffic (and the noise they produce) was present in the Sound during testing. Some additional MK24 tests were conducted in slightly deeper water in Block Island Sound, also with satisfactory results. In reviewing the testing program results, no mention is made of any effects from wave noise or shallow water reflections degrading performance.
One has to ask why the Mk24 acoustic system operated satisfactorily under conditions approximating those you describe as rendering Cutie ineffective; so far as I can determine, both torpedoes had the same acoustic systems.
Well, this question led me to dig around to find information relating to the performance of Cutie. The following is extracted from Milford, â€œUS Navy Torpedoesâ€, Part IV: WW II development of homing torpedoes 1940-1946, published by the Submarine Review:
â€œTwo other passive homing torpedoes saw service in WW II. The Mk.27 torpedo was a submarine launched anti-escort weapon based on the Mk.24. The original Mk.27 Mod 0 was a minimally modified Mk.24 with wooden rails to fit 21 inch torpedo tubes, a floor switch (instead of a ceiling switch) so it would not attack the launching submarine, and various arming, warm-up and starting controls to suit a torpedo tube, swim-out launch mode. Eleven hundred MK.27 Mod.0 torpedoes, known as CUTIE, were built by Western Electric and delivered between June 1944 and April 1945. Production on a subsequent order for 2300 torpedoes continued until the end of the war. One hundred and six (136) were fired against enemy escorts. Thirty-three (33) hits sank 24 ships and damaged 9 others...â€ One might take this as quite remarkable results considering this torpedo was only in use for about a year of the war.
US aircraft dropped 142 Fidos on U-boats, sinking 31, and damaging 15. (these numbers do not include Fido drops and U-boats sunk and damaged by the other Allies). These results were judged to be highly successful and far exceed the â€œkill ratioâ€ achieved with depth charges. (see reference note below)
It seems from these figures that Cutieâ€™s score against surface ships compared favorably with Fidoâ€™s score against U-boats. I would be very interested to read your sources of information on CUTIE performance. Perhaps there is an explanation for these apparently differing results reported for MK27.
Ref: US Navy OEG Study No. 289, 12 August 1946