Osprey's Big Reveal: X-Planes

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XPL: Northrop Flying Wings

Half a century before the ‘flying wing' B-2 stealth bomber entered service, John K. ‘Jack’ Northrop was already developing piston-engined prototypes that looked remarkably similar.

The flying wing is a theoretically very efficient design, and World War II brought a need for very long-range bombers. Northrop, a flying wing enthusiast, received a contract for a 172ft-span bomber prototype, to be known as the B-35. Several of these were built, gradually evolving into the definitive XB-35 configuration. But engineers struggled to overcome the design challenges and several pilots were lost in crashes. The design was developed into a jet-engined successor, the YB-49, but the challenging programme was cancelled in the 1950s.

The concept influenced other highly innovative areas, such as the XP-56 and MX-324 Rocket Wing prototype fighters. But the greatest legacy was the first operational flying wing – the Northrop Grumman B-2 stealth bomber, which used much of the hard-won experience from the pioneering programmes of half a century before.

XPL: Douglas D-558

The D-558 series were the US Navy’s contribution to America’s early generation of pure research aircraft. Their aim was to explore flight beyond Mach 1 with no direct military production potential. Both series of D-558 were well-designed, strong and efficient aircraft which enabled test pilots to tackle the unknown in comparative safety. Although delayed by their innovative, troublesome powerplants in most cases and limited by the cost of their air-launched sorties they went well beyond their original Mach 1 speed objective and continued to generate information that provided design solutions for a whole generation of supersonic combat aircraft, such as the F8U Crusader and F3H Demon.

Douglas also proposed a Mach 9 Phase III D-558 which lost out to the North American X-15. The D-558s, being closer to a service specification than Bell’s aircraft, also acted as a failsafe back-up to the more radical X-1 designs. It continued to produce ‘flight’ research results while wind-tunnel and computerized ‘ground’ technology caught up with the supersonic era.

XPL: Jet Prototypes of World War II

While World War II raged, pioneering aircraft and engine designers were busy developing the world’s first practical jet-powered research aircraft, to test and prove the new technology.

Throughout the war, British, German, and Italian designers all built experimental aircraft in order to achieve an effective engine and airframe partnership that could harness the potential of the jet engine. These included the German Heinkel He 178 research aircraft and He 280 jet fighter prototype, the famed British E.28/39 research aircraft built by Gloster Aircraft as well as the stillborn E.5/42 fighter and E.1/44 Ace fighter prototype, and finally the remarkable Italian Caproni-Campini N.1/CC 2 motorjet research aircraft.

XPL: The Wright Flyers 1899–1916

Orville and Wilbur Wright, two bicycle-making brothers from Dayton, Ohio, secured their place as the most famous names in aviation history when, on December 17, 1903, they made the first powered, controlled, and sustained heavier-than-air flight.

The Wrights’ progression from theory to analyses, then to ground-testing components and wing shapes, and then flight-testing kites, gliders, and their first powered airplane marked the world’s first successful ‘X-Plane’ research and development program. In the process, they not only achieved that milestone ‘first’ of 1903 – the Wright Flyers also included the world’s first reusable aircraft of 1905, the first production aircraft of 1907, the world’s first military aircraft (of the US Signal Corps) of 1909, and the first coast-to-coast trans-American flight in 1911, plus a series of other fascinating designs, before their aircraft began to be eclipsed by other designers.