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When Britain’s Royal Air Force became the first independent air force in 1918, its raison d’être was long range strategic bombing. However, after World War I and associated budget cuts, the idea languished and it was not until 1936 that the British Air Ministry issued Specification B12/36 calling for a long range, four engine strategic bomber that could carry a bomb load of 14,000 pounds.
Curiously, it also specified that the wingspan should not exceed 100 feet so the aircraft could fit inside current RAF hangars, although the most common type of RAF hangar could open to more than 125 feet.
Britain’s pre-eminent flying boat builder, Short Brothers, submitted a design with a wing based on its four engine Sunderland flying boat, but the wing had to be dramatically shortened, thickened and reshaped to meet the 100 foot limitation.
Short flew a half-scale prototype and found the wing shape made the take-off run too long. To get the proper wing angle for a reasonable take off run, the new aircraft ― now named the “Stirling” ― was given very long, stalky landing gear.
Testing proved to be an adventure. On its first flight on May 14, 1939, the landing gear collapsed on landing ― a flaw that was to haunt the Stirling for its whole career. The second prototype suffered a major engine failure a few months later but recovered safely.
Heavy bombing of the Short plant during the Battle of Britain slowed production, and it was not until February 1941 that the Stirlings flew their first operational mission. It quickly became a major weapon for RAF Bomber Command, but as the war progressed, more problems began to crop up.
While the Stirling could carry 14,000 pounds of bombs, its 40-foot-long bomb bay had two structural dividers running down the middle. This meant the largest bomb it could carry was only 2,000 pounds, while the RAF was beginning to use the 4,000 pound “cookie” bomb and plans for even larger bombs were in the works.
A far more serious problem was the thick, short wing, which limited its service ceiling with a full bomb load to about 12,000 feet. This meant Stirlings attacking targets in Italy had to fly through rather than over the Alps.
More importantly, on missions over Germany, Stirlings were always the bombers
flying at the lowest altitudes.
The Luftwaffe concentrated on the low-flying Stirlings because the heavy German night fighters found it easier to reach them.
The Stirling crews also found themselves in the envelope of very efficient light anti-aircraft that could not reach higher flying bombers.
In one period of 19 raids, Stirling losses were almost 16 percent as opposed to the losses of the other major RAF bombers ― the Lancaster (5.6 percent) and Halifax (8.9 percent).
Still, many Stirling crews liked their aircraft. The tail turret, which covered the most vulnerable area, was very efficient and the Stirling’s thick wing made it very maneuverable.
Beginning at the end of 1943, Stirlings were replaced in Bomber Command’s main force, but a new role waited.
The RAF needed a powerful aircraft to tow heavy gliders for D-Day and Stirlings, without nose and dorsal turrets, became mainstays for towing gliders during the Battle of Normandy. They also played a major part of Operation Fortitude, the highly successful D-Day deception operations, largely by laying long corridors of chaff that looked like a separate invasion fleet.
While the Stirling was the only British World War II bomber designed from the start with four engines, it will be remembered mainly for the heavy losses it suffered as the result of complying with the short sighted RAF wing span requirement.
(For questions or comments, contact Dr. Michel at marshall.michel@spangdahlem.af.mil.)
