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Airplanes that Transformed Aviation

Sixteen historic designs that changed the game.

8. Dornier Wal

The name Dornier is forever associated with a series of Second World War bombers and with the awkward-looking Do X flying boat of 1929, which became the first transatlantic airliner. But behind them was the airplane that company founder Claude Dornier credited with saving his firm: the Dornier Wal (“Whale”). “The Wal made Dornier,” he once remarked, and besides, it made oceanic flying boat operations practical. Blending Duralumin (an aluminum alloy) construction techniques derived from Dornier’s years at Zeppelin with rugged ship-building practice, the twin-engine Dornier Wal, which first flew in 1922, embodied significant design refinement, including use of a high, semi-cantilever monoplane wing and broad stabilizing sponsons in place of higher-drag and more complex wingtip floats. Thus the Wal anticipated the design of the most successful large passenger-carrying seaplanes, aircraft such as the Martin M-130 (the famed “China Clipper”) and the Boeing 314. But it was a notable international success itself. More than 300 were built in Italy, Netherlands, Japan, Spain, and Russia, for both military and civil purposes, using a variety of engines. It established a number of world records for speed and payload, spanned the Atlantic and circled the globe, and gave rise to more powerful three- and four-engine streamlined successors. It was a favorite mount for explorers: Indeed, the Wal was the first aircraft to significantly influence the study of Earth, its polar regions, and the environment in general.

Further reading:
Roald Amundsen and Lincoln Ellsworth, Air Pioneering in the Arctic (National Americana Society, 1929);
M. Michael van der Mey, Dornier Wal: “A Light Coming Over the Sea” (LoGisma editore, 2005).

9. Douglas DC-1

The Douglas DC-1, created by a team led by Arthur E. Raymond, may be said to be the first scientifically designed American airplane. It blended the research and experience of industry, federal research laboratories such as the National Advisory Committee for Aeronautics (NACA), and academic centers, specifically the Guggenheim Aeronautical Laboratory of the California Institute of Technology, where its shape was refined by extensive wind tunnel testing. The aircraft utilized the all-metal, multi-cell structure John Knudsen Northrop had developed previously for his Alpha of 1930 (when, ironically, he was partnered with Boeing). The 12-passenger, twin-engine DC-1 blended advanced aerodynamics (typified by turbulence-reducing wing-fuselage fillets, payload-enhancing wing flaps, and refined engine cowling placement); higher-strength aluminum alloys; a retractable landing gear; controllable pitch propellers; and a lightweight monocoque fuselage structure. Its superiority over the rival Boeing 247 was evident from the outset: Little more than a week after its first flight, TWA chief pilot D.W. “Tommy” Tomlinson, one of the most experienced test pilots of the time, reported jubilantly to company president Richard W. Robbins: “I think we have a fine airplane.” Indeed: It spawned the DC-2 and DC-3 and an entire “DC generation,” its shape as symbolic of 1930s Modernist aeronautics as Boeing’s swept-wing 707 was of the 1950s, or Concorde’s ogival double-delta was of the 1970s.

Further reading:
D.W. Tomlinson to R.W. Robbins, 9 July 1933, Box 124–517, Charles A. Lindbergh Papers, Yale University Library;
D.W. Douglas, “The Douglas DC-1 Airliner,” Aero Digest, vol. 23, no. 4 (Oct. 1933);
Douglas J. Ingells, The Plane That Changed the World (Aero Publishers, 1966);
Peter W. Brooks, The Modern Airliner (Putnam, 1961).

10. Lockheed XC-35

Lockheed’s XC-35 was the world’s first aircraft specifically constructed with a pressurized passenger cabin and, as aerospace medical historian Douglas Robinson notes, is “the true ancestor of all modern pressurized airliners.” Credit for the cabin goes to structures experts Major Carl Greene and John Younger, both of whom worked for the Air Corps Engineering Division at Wright Field (now Wright-Patterson Air Force Base) in Ohio. They worked with Lockheed to redesign the fuselage of the Lockheed 10A Electra, adding two turbosuperchargers to its radial engines both to improve altitude performance and to feed air to the cabin. Designated XC-35 and delivered to Wright Field in May 1937, it began flight testing in July, flying up to 33,000 feet while maintaining a cabin pressure of 9.5 pounds per square inch. The XC-35 underwent an extensive series of high-altitude flight tests, proving the practicability of pressurizing the cabin. So confident were Army Air Corps leaders of its safety that they allowed it to be used as an executive transport for Louis Johnson, the assistant secretary of war. The XC-35 won the 1937 Collier Trophy for the Air Corps. But more significantly, it pointed the way for pressurized bombers and transports, the first of which were Boeing’s B-29 and Model 307.

Further reading:
National Museum of the U.S. Air Force XC-35 Data Sheet;
XC-35 Curatorial File, National Air and Space Museum;
Douglas Robinson, The Dangerous Sky (University of Washington Press, 1973).

11. Gloster E.28/39

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