TBD's short life as a high-tech flyer

BY LARRY MERRITT

In the mid-1930s, a new era of naval aviation arrived. Aircraft builders moved to all-metal monoplane designs, and construction began on the first ships designed from keel up as aircraft carriers.

The U.S. Navy realized the age of the classic open-cockpit biplane was nearing an end. For operations from the new aircraft carriers, it needed faster and more capable aircraft.

In a 1934 competition for a new carrier-based torpedo bomber, Douglas Aircraft's XTBD-1 monoplane was pitted against more conservative biplane entries from Great Lakes Aircraft Company and Hall Aircraft Corporation.

The XTBD-1 made its first flight on April 15, 1935, from Douglas facilities in Santa Monica, Calif. With its single-wing, retractable landing gear and three-bladed, controllable-pitch propeller, it incorporated all the latest technology.

After a seven-month flight-test program, the Navy decided against the biplane designs and placed an order for 129 production models of the Douglas TBD-1.

The first operational TBDs reached Navy squadrons in November 1937. It was the Navy's first all-metal monoplane torpedo bomber, the first carrier-based plane with an enclosed cockpit, and the first to use wheel brakes on its main landing gear. While most carrier-based aircraft of the day had manually folded wings for storage aboard ship, the TBD featured hydraulically powered folding wings.

The plane had a crew of three--pilot, bombardier and gunner--and carried a half-ton torpedo or two 500-pound (227-kilogram) bombs.

Its cockpit featured the latest in electronic gear. With an automatic pilot, full radio and intercom systems, the TBD was far ahead of anything then in carrier service. "It's got everything but the kitchen sink," said one sailor after looking it over.

Pilots loved the plane's ruggedness and stability. It was rock-steady when landing aboard a carrier.

However, the TBD had its drawbacks. Under the best of conditions, its top speed was barely 200 mph (322 kilometers per hour), and its maneuverability was limited. It was a straight-and-level airplane.

In December 1941, after the attack on Pearl Harbor, TBD Devastators formed the backbone of the Navy's carrier torpedo force in the Pacific. During hit-and-run raids against Japanese bases in the Central Pacific in early 1942, TBDs sank two transports and destroyed or damaged 10 other vessels. In May 1942, during the Battle of the Coral Sea, TBDs helped sink one carrier and heavily damaged another. These early missions, however, underscored the TBD's performance shortcomings. The Devastator also experienced problems with its main offensive weapon: Its torpedoes often failed to explode.

The TBD next saw action in the Battle of Midway in June 1942. This was a complete victory for the U.S. Navy, but of the 41 Devastators that took part in the battle's first day, only six made it back to their carriers. The TBD's slow speed and lack of maneuverability made it easy prey for the famous Japanese Zero fighter.

Nevertheless, the bravery of the TBD's crews played a pivotal role in the battle's outcome. Their low-level torpedo attacks against four aircraft carriers forced the Japanese air combat patrols down to the wave tops to destroy them. This left the higher altitudes above the Japanese fleet unprotected when 50 Navy SBD Dauntless bombers dived down from 15,000 feet (4,570 meters). Their unopposed attacks shattered the opposition's carrier force, sinking three carriers. In less than 10 minutes, the course of the Pacific War changed permanently.

The TBD Devastator, an aircraft of advanced design in 1935, was obsolete seven years later. Its first six months of combat were its last. The TBD was withdrawn from front-line service in the summer of 1942. A few continued in service as advanced trainers until the end of the war. But the plane that made the biplane obsolete on carrier decks was itself quickly consigned to history.

lawrence.e.merritt@boeing.com