Technology and Operations
This forum is for discussing technological & operational matters pertaining to U-boats.
Re: Depth Charges and ASDIC/Sonar
Posted by:
Don Baker
()
Date: August 14, 2002 01:50PM
Ken
Interesting you should mention Fido. The pilots were restricted to certain conditions under which they could drop a MK24. The submarine had to be submerged before the drop so as to preclude the possibility of anyone on the sub visually observing the weapon.
During MK24 development all the paperwork referred to it as the MK24 Mine.
Some of the carriers kept Mk24 completely shrouded and only certain ordnancemen could be on hand when Fido was being loaded into the TBFs. For some reason this procedure was not observed on USS Guadalcanal and I remember watching an ordnance crew loading one into a TBM on the flight deck. Well, I could tell the difference between a depth charge and a torpedo and this thing, with a propellor on one end, looked like a stubby little torpedo to me, unlike anything I had ever seen before. When I asked one of the ordnancemen what it was he grinned and called it a "Hotdog". Since everything going into the belly of a TBM was intended for dropping on a submarine it didn't take a genius to figure out what it was except none of us knew it could maneuver in three dimensions.
The reason for all this secrecy and security was because the MK24 guidance system signal processing was extremely simple minded by todays standards. It was a passive acoustic homing system simply responding to the loudest signal and therefore could have been easily countermeasured if its existence was known in much the same way a simple "Foxer" could decoy a German acoustic torpedo.
Even so the MK24 far exceeded depth charges and hedgehogs in effectiveness. In fact it was so effective the Navy actually reduced the procurement quantities - they just didn't need the planned numbers calculated to get the job done.
Don B
Interesting you should mention Fido. The pilots were restricted to certain conditions under which they could drop a MK24. The submarine had to be submerged before the drop so as to preclude the possibility of anyone on the sub visually observing the weapon.
During MK24 development all the paperwork referred to it as the MK24 Mine.
Some of the carriers kept Mk24 completely shrouded and only certain ordnancemen could be on hand when Fido was being loaded into the TBFs. For some reason this procedure was not observed on USS Guadalcanal and I remember watching an ordnance crew loading one into a TBM on the flight deck. Well, I could tell the difference between a depth charge and a torpedo and this thing, with a propellor on one end, looked like a stubby little torpedo to me, unlike anything I had ever seen before. When I asked one of the ordnancemen what it was he grinned and called it a "Hotdog". Since everything going into the belly of a TBM was intended for dropping on a submarine it didn't take a genius to figure out what it was except none of us knew it could maneuver in three dimensions.
The reason for all this secrecy and security was because the MK24 guidance system signal processing was extremely simple minded by todays standards. It was a passive acoustic homing system simply responding to the loudest signal and therefore could have been easily countermeasured if its existence was known in much the same way a simple "Foxer" could decoy a German acoustic torpedo.
Even so the MK24 far exceeded depth charges and hedgehogs in effectiveness. In fact it was so effective the Navy actually reduced the procurement quantities - they just didn't need the planned numbers calculated to get the job done.
Don B
