The Airplane - Jay Spenser [58]
During World War II, the Messerschmitt Me 262—the world’s first operational jet fighter—was 100 mph (160 km/h) faster than the best Allied propeller fighters. It had modestly swept wings, but evidence suggests that Adolf Busemann’s insights were not responsible for this design decision. Instead, its wings angled back to keep the airplane in balance after different engines had to be substituted during its development.
Adolf Busemann’s 1935 speculations in Rome were not yet broadly appreciated even a decade later. But as the war in Europe drew to an end in the spring of 1945, Allied technical intelligence teams advancing through Hitler’s collapsing Third Reich came across wind-tunnel and other research data that greatly excited U.S. experts. Thanks to these finds, two American jet airplanes then in development—the North American F-86 Sabre and the Boeing B-47 Stratojet—were redesigned in midstream to incorporate swept wings.
Coincidentally in 1945, NACA aerodynamicist Robert T. Jones independently rediscovered the value of wing sweep. The elegant mathematical understanding of its benefits that Jones provided went beyond what Busemann had come up with. All at once, wing sweep was firmly at the forefront of human thought.
As World War II raged, the U.S. Army Air Forces embarked on high-speed flight research in partnership with fighter-plane manufacturer Bell Aircraft in New York State. This critical research program was well under way before the benefits of wing sweep became known.
Not wanting to lose time, and fearful of introducing a potentially confusing new variable, the USAAF—which became the separate U.S. Air Force in September 1947—did not have Bell redesign its rocket-powered X-1 research plane with swept wings. Consequently, when USAF fighter ace and test pilot Captain Charles E. “Chuck” Yeager broke the sound barrier on October 14, 1947, he did so with straight wings.
Shortly before the X-1’s historic flight, North American Aviation in Los Angeles flew its F-86 Sabre, the first U.S. swept-wing jet fighter, which could exceed the sound barrier in a dive. And not long after Yeager’s success, the Boeing B-47 Stratojet jet bomber flew in Seattle on the forty-fourth anniversary of the Wright brothers’ flight. An arrow to the future, the high-subsonic B-47 was the world’s first large production airplane with swept wings.
On October 14, 1947, USAF Capt. Chuck Yeager broke the sound barrier in the rocket-powered Bell X-1.
National Air and Space Museum, Smithsonian Institution
The delta wing, another significant application of wing sweep, features a triangular planform that keeps the wing entirely within a supersonic airplane’s shock cone for less drag. Initially proposed by German aerodynamicist Alexander Lippisch, delta-wing airplanes are generally semi-tailless because the aft-mounted wing also acts as the horizontal tail. Many American and French jet fighters have had delta wings, as have British bombers. The Concorde supersonic transport is also a delta-wing aircraft.
Fittingly, it is in commercial air travel—by far the airplane’s most important role—that wing sweep has yielded the greatest benefits. Boeing gave its breakthrough 707 airliner the same 35 degrees of wing sweep as the B-47, although the two designs are otherwise entirely different. Douglas was a bit more conservative with its first jet, the DC-8 of 1959, which had 30 degrees of sweep. To this day, the subsonic jetliner with the greatest amount of wing sweep is the Boeing 747, with 37.5 degrees. The world’s first commercial jet transport, the de Havilland Comet of 1952, had only modest wing sweep and thus could not match the performance of the