In March 1939, the U.S. Navy's (USN's) Bureau of Aeronautics (BuAer) completed a detailed Type Specification for a new carrier-based torpedo bomber to replace the Douglas TBD Devastator, q.v., and invited the aviation industry to bid on the design and construction of experimental aircraft. A number of criteria were specified including the provision that the torpedo or bombs must be carried internally. By August 1939, six manufacturers had submitted thirteen design proposals and by early autumn, BuAer was concentrating on three designs submitted by the Brewster Aeronautical Corporation, the Grumman Aircraft Engineering Corporation and the Vought-Sikorsky Division of the United Aircraft Corporation located in Stratford, Connecticut. (Due to lack of sales of Sikorsky aircraft, the United Aircraft Corporation had merged the Chance Vought Aircraft Division and the Sikorsky Aircraft Division into the Vought-Sikorsky Division in January 1939.) A Contract for two Grumman XTBF-1 Avengers, q.v., was signed on 8 April 1940; two weeks later, the USN signed a contract with Vought-Sikorsky for one XTBU-1 as a backup plane in the event that the Grumman design failed.

The USN was so impressed with the Grumman XTBF-1 mockup, that it signed a contract for 285 production aircraft 7½ months before the aircraft made its first flight on 7 August 1941. Meanwhile, Vought-Sikorsky began work on the XTBU-1 but this prototype did not make it's first flight until 22 December 1941, twelve days before the first production TBF-1 rolled off the Grumman assembly line. This was the story of the TBU/TBY throughout the war, i.e., too little and too late.

The XTBF-1 and XTBU-1 had a very similar layout. Both were large single-engine, all-metal, mid-wing monoplanes with retractable landing gear and folding wings. The landing gear of the XTBU-1 rotated 90 degrees and retracted to the rear so that the tire lay flat in the wheel well; the wings folded upward for storage.. The crew of three, pilot, navigator/ventral gunner and radioman/turret gunner, sat under a long greenhouse canopy with a power operated turret at the aft end. A ventral gun position was also included just behind the torpedo/bomb bay.

The XTBU-1 was transferred to Naval Air Station (NAS) Anacostia, District of Columbia, in March 1942 for flight tests by USN personnel. The aircraft was equipped with a novel feature, an automatic system with which one control lever lowered the landing gear and flaps, and set the propeller pitch and mixture for landing. During one simulated carrier landing, the tail hook caught and tore the entire rear off the aircraft and it went bouncing down the runway. The two sections were returned to Vought-Sikorsky and it took four weeks to repair the machine. The day the work was finished, it was being pushed across the street to a hangar when a Navy cadet lost control of his training aircraft while taxiing and the trainer smashed into the rear of the XTBU-1 completely chewing up the tail. The aircraft was again repaired and finally accepted by the USN. During testing, it was found that the maximum speed of the XTBU-1 was over 40 mph (64.4 km/h) faster than the TBF-1 which impressed the Navy and they wanted to place an order for 1,000 aircraft. However, Vought-Sikorsky was heavily involved in the manufacturing of the OS2U Kingfisher, q.v., and the F4U Corsair, q.v., and there was no spare production capacity. The production order remained in limbo until late1943 when a new manufacturing plant owned by Consolidated Vultee Aircraft Corporation was completed in Allentown, Pennsylvania. With this new manufacturing capacity available, the USN signed a contract with Consolidated Vultee on 6 September 1943 for 1,000 TBY-2s. The TBY-2 was similar to the XTBU-1 but had a more powerful engine and was equipped with radar; the radome was located under the starboard (right) wing. The first production TBY-2 flew on 20 August 1944 and was delivered to the USN at the Naval Air Material Center, Philadelphia, Pennsylvania, on 7 November 1944 for testing. By this time, every torpedo squadron in the USN was equipped with the TBF, or the Eastern Aircraft TBMm Avenger and the TBY was not needed. Only 180 TBY-2s were built before the contract was canceled; the last aircraft was delivered in September 1945. The contract for 600 improved TBY-3s was also canceled before any were built.

Production History

XTBU-1: One prototype initially powered by a 1,800 hp (1,342 kW) Pratt & Whitney XR-2800-6 18-cylinder, twin-row, air-cooled, radial engine; it was later equipped with a 2,000 hp (1,491 kW) R-2800-2 engine.
TBY-1: Not built
TBY-2: 1,000 production aircraft similar to the XTBU-1 but powered by a Pratt & Whitney 2,100 hp (1,566 kW) R-2800-22 18-cylinder, twin-row, air-cooled, radial engine and equipped with radar; the radome was located under the starboard (right) wing. Only 180 were built; the remaining 820 on the contract were canceled.
TBY-3: 600 improved TBY-2s were ordered but all were cancelled before production began.