History
In June 1942, the aftermath of the Battle of Midway showed the US Navy the need for an advanced torpedo bomber capable of carrying more weapons load and flying at long range. At the same time, the Navy began to expand the size of its aircraft carrier fleet, as it ordered Essex-class and Midway-class carriers.
Douglas designers had been working on a replacement for the TBD Devastator torpedo bomber since 1939. They approached the Navy officials with the designers’ proposal design with an initial twin-engine configuration to provide the necessary power for versatility, such as undertaking the torpedo bomber, reconnaissance, and level-bombing roles.
The twin-engine design was later dropped in favor of the single-engine design. In November 1942, the Navy contracted with Douglas Aircraft Corporation to develop and produce their new bomber. Impressed with the mockup aircraft in early 1943, the Navy signed a contract and ordered the construction of two flyable prototypes and a static testbed, so the project officially began in late October 1943. These prototypes were designated XTB2D-1 and under the name of Skypirate.
The XTB2D-1 was the colossal aircraft of its time built in the United States. It had a wingspan of 70 feet, with a total wing area of 605 square feet, larger than the Avenger’s 54-foot wingspan. Its huge tail was six feet taller than the Avenger’s. The empty weight was over 18,000 pounds, and the maximum was over 34,000 pounds. The aircraft’s wings could be folded for the aircraft carrier storage and had the arrestor gear for the recovery operations. The aircraft’s wings had slotted flaps, with the center segments serving as dive flaps and the outboard segments also acting as ailerons. The slotted flaps could be dropped to relieve stress at high speeds or when turning.
The XTB2D-1 was powered by a single Pratt & Whitney 3,000-horsepower Wasp Major XR-4360-8 with a supercharger. It was driven by an eight-bladed, contra-rotating propeller system as a favored alternative to the conventional twin-engine configuration. The aircraft had a unique exhaust system for the engine; the exhaust ports from cylinders in alternating rows were combined to reduce the effects of backpressure, forcing the exhaust gas pressure out and efficiently increasing fresh air intake in the cylinders.
A modern tricycle undercarriage was fitted to provide better visibility forward and allow the large blades the necessary clearance while also simplifying weapons loading. The bomb bay was featured in the original design; however, this was eliminated, so the torpedoes and bombs would have to be carried externally with low-mounted wings. Each wing could hold two hardpoints for carrying 2,100-lb torpedoes or two bombs.
The aircraft was planned to have a single 2 x .50-cal dorsal turret and a single 1 x .50-cal ventral turret. It was also prepared to have four wing-mounted 20-mm cannons or four wing-mounted .50-cal machine guns.
Earlier in March 1943, 23 pre-production aircraft were ordered by the Navy; however, the TB2D-1 project faced slow progress, as the construction of the USS Midway aircraft carrier was delayed. It was not until October 1943 that the efforts resumed to make substantial progress with the two XTB2D-1s and a static testbed in construction.
On February 18, 1945, the first Skypirate prototype was rolled out of El Segundo, California. This prototype lacked both offensive and defensive armament. It later first flew on May 8, 1945. The second prototype was completed and flew later in the summer of 1945. Although the flight trials proceeded on schedule, the testing faced significant challenges, as one of the prototypes ripped its flap segments away but successfully landed safely. Other problems with the propeller surfaced and caused all flight tests to be suspended until after the work. These problems delayed the project from going further into the production stage. Additional resources for the project were halted due to the disruptions from the war.
The project resumed in 1947 at a slow pace; however, the Navy had started to lose interest in this expensive piston-engined project as it was considered obsolete. The surrender of the Japanese forces in the Pacific and delays in the Midway-class aircraft carriers caused the Navy to seek something else to fill the XTB2D-1’s role at the dawn of the jet and turboprop engine. Ultimately, the 23 pre-production aircraft on order were canceled. The flight trials were suspended, and the two prototypes were eventually scrapped in 1948.
