The Douglas TBD Devastator was an American torpedo bomber of the United States Navy. Ordered in 1934, it first flew in 1935 and entered service in 1937. At that point, it was the most advanced aircraft flying for the Navy and possibly for any navy in the world. However, the fast pace of aircraft development quickly caught up with it, and by the time of the Japanese attack on Pearl Harbor the TBD was already outdated.
The Devastator performed well in early battles, most notably in the Battle of Coral Sea, but earned notoriety for a catastrophic performance during the Battle of Midway in which 41 Devastators recorded zero torpedo hits with only six surviving to return to their carriers. Vastly outclassed in both speed and maneuverability by the Mitsubishi Zero fighters they faced, most of the force was wiped out with little consequence except to distract the Zeros from the SBD Dauntless dive bombers that sank four carriers and a heavy cruiser. Although much of the Devastator's dismal performance was later attributed to the many well-documented defects in the US Mark 13 torpedo, the aircraft was withdrawn from frontline service after Midway, being replaced by the Grumman TBF Avenger.
Design and development
The Douglas XTBD-1 was ordered on 30 June 1934 after being one of the winners of a US Navy competition for new bombers to operate from its aircraft carriers. Other aircraft also ordered for production as a result of the competition included the Brewster SBA, the Vought SB2U Vindicator, and the Northrop BT-1, the last of which would evolve into the Douglas SBD Dauntless. The Great Lakes XB2G, Great Lakes XTBG, Grumman XSBF, Hall XPTBH and Vought XSB3U were also tendered to the specification but were not developed beyond prototype status.
The XTBD Devastator flew for the first time on 15 April 1935 while marking a number of "firsts" for the US Navy. It was the first American carrier-based monoplane to be widely used, the first all-metal naval aircraft, the first with a completely enclosed cockpit, the first with power-actuated (hydraulically) folding wings. A semi-retractable landing gear was fitted, with the wheels protruding below the wings to potentially limit damage to the aircraft in a "wheels-up" landing. A crew of three was normally carried beneath a large "greenhouse" canopy almost half the length of the aircraft. The pilot sat in front; a rear gunner/radio operator took the rearmost position, while the bombardier occupied the middle seat. During a bombing run, the bombardier lay prone, sliding into position under the pilot to sight through a window in the bottom of the fuselage, using the Norden bombsight.
The normal TBD offensive armament consisted of either a Bliss-Leavitt Mark 13 aerial torpedo or a bomb carried semi-recessed in the fuselage. Alternatively, three general-purpose bombs (one under each wing root and one inside the fuselage), or twelve fragmentation bombs (six under each wing root), could be carried. This weapons load would often be used when attacking Japanese targets on the Gilbert and Marshall Islands in 1942. Defensive armament consisted of a Browning machine gun for the rear gunner. Fitted in the starboard side of the cowling was either a or M2 Browning machine gun.
The powerplant was a Pratt & Whitney R-1830-64 Twin Wasp radial engine, a development of the prototype's Pratt & Whitney XR-1830-60/R-1830-1. Other changes from the 1935 prototype included a revised engine cowling and a raised cockpit canopy to improve visibility.
The XTBD had a flat canopy that was replaced on production models by a higher, domed canopy with a rollover bar. Other than requests by test pilots to improve pilot visibility, the prototype easily passed its acceptance trials that ran from 24 April to 24 November 1935 at NAS (Naval Air Station) Anacostia and Norfolk bases. After successfully completing torpedo drop tests, the prototype was transferred to the for carrier certification. The extended service trials continued until 1937 with the first two production aircraft retained by the company exclusively for testing.