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Decoys and Obscurants |
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STATISTICS Equipment doesn't always work as designers intend. In his book The Atlantic Battle Won, Samuel E. Morison describes how the the operation of the newly-installed smoke generators worked during a German aircraft attack: "Each escort had recently acquired a new smoke screen generator, located in the after-steering engine room with the nozzle between the two depth charge racks on the fantail. In the final seconds of the attack, these generators overheated, and about six of them flared up, shooting flames 10 feet into the air. The German pilots, seeing this phenomenon, thought they were having a field day, when in fact they had hit nothing..."
USS Tweedy (DE532) making smoke with another DE off the coast of Florida.
USS Tweedy (DE532) making smoke off Key West, Florida.
USS Hemminger photo courtesy of Robert E. Taylor, Email: taylor794@msn.com |
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| STATISTICS Name: Acoustic Decoy (Foxer) Year of Construction: 1943 (Approx) Weight: Varied but up to 6000 pounds. Effective Range: Pulled behind ship on 200 yard cable. No photo available. The foxer was designed to counter the T-5 German Naval Acoustic Torpedoes (GNAT) that was introduced in the second half of August, 1943 and was designed to home in on the cavitation noise produced by a ship's propellers. Designed by the British, the "Foxer" was a 3000-pound fixture of hollow pipes with holes in them that resonated (read "banged together") when drawn through the water, confusing acoustic torpedoes. A variation consisted of two such tubes towed about 200 yards behind a ship, that repeatedly banged against each other. The American version of the "Foxer", code-named "FXR" was in production by 1943. Destroyer Escorts towed "FXRs" and generated a significant acoustic signature intended to spoof the German's T-4 Falke (Falcon) and T-5 Zaunkoenig 1 (Wren) passive acoustic torpedoes. Not all DEs were equipped with this device. The disadvantage of using the FXR was twofold; it could only be towed at 14 knots, and it's noise greatly reduced the effectiveness of the sonar. The FXR was also heavy (up to 6000 pounds for some variations) and tended to wear out fast. Late in the war the Germans developed the T-11 Zaunkoenig II, designed specifically to ignore towed decoys and noisemakers. Fortunately, it was never used in battle. The Canadians had a device similar to the FXR they called "CAT" (Counter-Acoustic Torpedo). During a U-Boat torpedo attack
a sonarman picked up the distinctive hiss of an approaching fish. "I
ran out on the bridge to prepare for an explosion. I looked over the side
in time to see the torpedo streak on by about 10 feet away from the hull!
An order had been given to stream FXR, and sure enough the torpedo headed
for it and blew up well astern!"
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 Zaunkoenig search pattern
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This is the Mark 6 Decoy, called Fanfare. These noisemakers were post-WW2 replacements for the the Foxer and were towed behind the ship to decoy acoustic homing torpedoes like the German Naval Active Torpedo (GNAT). The Fanfare consisted of a winch and the two cable drums visible in the photo. Mounted on the fantail, the two noisemakers were streamed much like the Foxer and towed behind the ship. The noisemakers were streamlined to reduce turbulence and were fitted with fins (visible in the top photo, but not in the black & white photo) to stabilize them in the water. Unlike Foxer, Fanfare was designed to emit sounds within the same frequencies as the ship's propellers, thus increasing the effectiveness of the system and making it harder for the enemy to use electronic filters on his torpedoes. A couple Sundays ago Bob Wilson (my Father-in-law) and I were down at the Washington Navy Yard cruising for chicks in the Navy museum. Somehow we ended up touring the USS Barry (DD-933) and discovered an intact Fanfare unit mounted on the stern. We picked up one of the transducers (yes, it took both of us... it weighed about 60 pounds) and Bob held it up long enough for me to snap this photograph (notice how red he is). Seconds later he passed out and dropped the transducer on his foot, ruining a perfectly good shoe. I had to drag his carcass out of the way to get the rest of the photos. Back to reality: Both the USS Barry and the Navy museum are worth a visit if you are in the Washington, DC area. The outdoor museum has several hull sections from both US and Japanese battleships that they tested munitions on. The most interesting is a 24"-thick section of hull from a Japanese battleship that we hit with a 16" AP round. There is also a one-of-a-kind WWI rail gun that the Navy Yard conceived, designed, built, tested and delivered to Europe---all within 90 days! The entire Navy yard is an interesting tour and there is enough to do and see to keep you busy all day. The Navy museum is being renovated and they expect to be completed by April 2001. In the meantime, they are operating a scaled down version that concentrates on the Korean war.
Update: I've had several emails suggesting the fanfare was never mounted on DEs, only the later Sumner/Gearing-class destroyers. I knew I'd seen it, it just took me a while to find the photo again... Here is the Cannon-class USS Roberts (DE749) with a fanfare mounted on the stern. National Archives #80-G-1028016 |
 Mk 6 Fanfare installed on a Gearing-class Destroyer
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This is the result of a German acoustic torpedo attack against the USS
Barr (DE 576) on May 29, 1944. On that evening the
USS Block Island (CVE-21) Hunter-Killer Group consisted of
the Ahrens (DE-575), Eugene E. Elmore (DE-686), Barr (DE-576),
Robert I. Paine (DE-578), and Buckley (DE-51). The
Ahrens was on her first wartime mission patrolling off the Block
Island's port bow. Suddenly, the carrier was simultaneously struck
by two torpedoes launched by U-549, one in the bow and the
second in the stern. Before long, a third torpedo hit the Block
Island and left her dead in the water and sinking. Without
streaming the FOXER, Lt. Cdr. H. H. Love, commander of the Barr,
headed to the port quarter of the Block Island, believing
the attacker was in that location. Slowing his ship to permit the sound
gear to work, no contacts were detected. Eight minutes later a tremendous
explosion blew the stern off the Barr and flooded the aft
sections. Fires broke out in the number two engine room and on the main
deck. Twisted wreckage covered the rear deck and bodies covered the entire
area. Adding to the confusion, the ship's steam whistle was stuck open,
creating so much noise that communication was impossible. As the Elmore
hunted down and killed the sub with a hedgehog attack, the Paine
and Ahrens rescued 674 Block Island survivors.
The Barr remained at GQ throughout the night. The ship was
taken under tow by Elmore to Casablanca at 4-5 knots. 17
sailors were killed in action. The Barr was towed to the Boston Navy Yard for repairs and received the APD conversion, steaming out of the yard as APD-39 in July 1944. It ended the war in Tokyo Bay. |
 Damage to the USS Barr caused by an acoustic torpedo. National Archives #80-G-319603 |
