Boeing B-47 Stratojet
The Boeing B-47 Stratojet was a six-jet strategic bomber that first flew in December 1947 and became Strategic Air Command's first large jet bomber fleet of the Cold War. Its 35-degree swept wing and pod-mounted engines set the layout that later bombers and jet airliners followed. Boeing, Douglas and Lockheed built 2,032 in bomber, reconnaissance and weather variants; the last Air Force Stratojet retired in 1969, and 23 airframes survive in American museums.
Why It Mattered
The B-47 was the world's first large swept-wing aircraft, and its layout — a swept wing with jet engines in pods beneath it — became the pattern that later bombers and jet airliners followed. Walter J. Boyne, a former director of the National Air and Space Museum, called it the most influential multijet aircraft in aviation history. In service the Stratojet gave Strategic Air Command its first large jet bomber fleet, which peaked in 1958 with 1,367 bombers in 28 wings, alongside 176 reconnaissance RB-47s. Boeing carried the formula into its 367-80 prototype, which used the B-47's swept wing and podded engines and led to the 707 airliner.
Design Notes
The B-47 began with a June 1943 Army Air Forces request for design studies of a multijet aircraft, and a formal requirement for a jet-powered medium bomber followed on 17 November 1944. The decisive step came in 1945, when Boeing's chief aerodynamicist George Schairer studied captured German swept-wing research and wrote back to Seattle urging that the swept wing be used on the new bomber. The result was a slender, flexible wing swept back 35 degrees, with six jet engines carried in pods beneath it. The wing was too thin to hold fuel or landing gear, so the aircraft stood on bicycle gear — tandem main wheels in the fuselage, with small outriggers retracting into the inboard engine nacelles. The crew of three shared a small pressurized compartment: the two pilots sat in tandem under a fighter-like canopy, and the radar observer, navigator and bombardier sat in a dark compartment in the nose. The thin wing brought aerodynamic problems, including pitch-up and high-speed aileron reversal, which were solved by fitting spoilers and vortex generators.
Operational History
The XB-47 rolled out in Seattle on 12 September 1947, and on 17 December 1947 Boeing test pilots Robbins and Osler made the first flight, from Boeing Field to Moses Lake, Washington. The first production order, for ten B-47As, came on 3 September 1948, and Douglas and Lockheed were brought in to build the aircraft alongside Boeing. Between them the three companies built 2,032 B-47s. The type entered operational service with Strategic Air Command in 1951 and became the backbone of its medium-bomber fleet through the 1950s. It was designed to drop nuclear weapons from high altitude, but as Soviet defences improved its crews took to low-level delivery, including a fighter-style bomb-toss technique. Reconnaissance RB-47s routinely probed Soviet airspace, and on 1 July 1960 a Soviet air defence fighter shot down an RB-47H over the Barents Sea; four of the crew died and two survived. The fleet's accident record was severe: across the type's lifetime, 203 aircraft were lost in crashes, with 464 deaths. Wing fatigue then broke the fleet's stride: six B-47s crashed between 13 March and 16 April 1958, and the reinforcement programme that followed, Project Milk Bottle, gave the fleet six more years of service. As the B-52 and intercontinental missiles took over the deterrent, the bombers were withdrawn, and by February 1966 all had been retired to the boneyard at Davis–Monthan Air Force Base, Arizona.
Afterlife
Reconnaissance versions outlasted the bombers, and the last Air Force Stratojet, an RB-47H, was retired in December 1969. The Museum of Flight's example, a weather-reconnaissance WB-47E, flew the last B-47 weather reconnaissance mission on 29 October 1969 and was delivered to Boeing Field the next day. It stood in outdoor storage there for decades before being restored to its bomber configuration; it is now displayed in the museum's Aviation Pavilion, on loan from the National Naval Aviation Museum. Twenty-three B-47 airframes survive in museum collections, all of them in the United States. The design's widest afterlife is in the air: the swept wing and podded engines the B-47 pioneered became the standard design for all modern jetliners.