The Whitehead No.21 was the aircraft that aviation pioneer Gustave Whitehead claimed to have flown near Bridgeport, Connecticut on August 14, 1901. A description and photographs of Whitehead's aircraft appeared in Scientific American in June 1901, stating that the "novel flying machine" had just been completed, and "is now ready for preliminary trials". The flight was reported in the August 18, 1901 issue of the Bridgeport Sunday Herald and was subsequently reprinted in other newspapers.
Photographs exist showing the aircraft on the ground, but there are no photographs known of the aircraft in flight. A drawing of the aircraft in flight accompanied the Sunday Herald article. The No.21 was a monoplane powered by two engines—one for the wheels during the ground run, the other driving the propellers for flight.
Mainstream aviation scholars dispute the flight; in 1980, C.H. Gibbs-Smith called the story a "flight of fancy". More recently, the 100th anniversary edition of Jane's All the World's Aircraft has credited Whitehead as the first man to build and fly an operational heavier-than-air flying machine.
The No.21 was a wire-braced monoplane with bat-like wings and triangular horizontal tail. There was no vertical fin, and lateral control was intended to be accomplished by shifting the pilot's body sideways.
The wings were constructed with radial bamboo ribs and covered with silk, and had a span of 36 ft (11 m). They had noticeable dihedral, which would have contributed to the aircraft's stability had it ever flown, and could be folded like a fan for transport.
The fuselage was of rectangular box section with constant height, curved to taper inwards at front and rear when seen from above. Four small wheels were fixed to the bottom.
Although having two engines and twin propellers, the aircraft was not a conventional twin. It had separate engines for ground running and flight, both designed and made by Whitehead. The ground engine was of 10 hp (7.5 kW) and drove the wheels to reach takeoff speed. Propulsion was then changed to a 20 hp (15 kW) acetylene engine driving two counter-rotating tractor propellers mounted on outriggers. The aircraft could supposedly take off under its own power and without assistance.
Later analysis by aviation historians concluded that the design as a whole was flimsy and aerodynamically unsound.
According to Whitehead and a reporter supposedly at the event, the monoplane's longest flight was 60 meters (200 feet) above ground for 800 meters (0.5 miles). These claims are contested. Whitehead did not keep a log book or document his work.
In an article in the August 18, 1901 issue of the Bridgeport Sunday Herald a reporter states that he witnessed a night test of the plane, at first unpiloted and loaded with sand bags, and later with Whitehead at the controls.
Whitehead's supporters say that he made four flights that day, which resulted in conflicting accounts from different witnesses. The conflicts have been used by opponents of the claims to question whether any flights took place.
A description and photographs of Whitehead's aircraft appeared in Scientific American in June 1901, stating that the "novel flying machine" had just been completed, and "is now ready for preliminary trials." The article included photographs showing the aircraft on the ground (but not in flight.)
Before his reported 14 August flight, Whitehead was quoted in a 26 July article in the Minneapolis Journal, credited to the New York Sun, in which he described the first two trial flights of his machine on 3 May. Andrew Cellie and Daniel Varovi were mentioned as his financial backers and assisted in the trial flights. The machine was unmanned and carried 220 pounds of sand as ballast and flew to an altitude of 40 to 50 feet for an 1/8 of a mile 650 feet (200 m). According to Whitehead, the machine flew a distance of 1/2 mile 2,600 feet (790 m) during its second test flight for one and one-half minutes before crashing into a tree. He also explained his desire to keep the location of any future experiments hidden to avoid drawing a crowd who might make a "snap-shot verdict of failure".
The flight was reported in the August 18, 1901 issue of the Bridgeport Sunday Herald and was reprinted in the New York Herald, the Boston Transcript and the Washington Times, which ran it on 23 August 1901. Within months, the story ran in nine other newspapers in all parts of the country, as far away as California and Arizona. A drawing of the aircraft in flight accompanied the Sunday Herald article.
In 1986 Andrew Kosch, a local high school teacher, led a team which built a replica of Whitehead's No.21. The replica, called 21B, had a few changes: the landing gear track was increased for better ground handling and two ultralight aircraft engines were used in place of the original steam and acetylene engines. On December 29, 1986, Kosch made 20 successful flights, the longest being 100 m (330 ft). The reproduction was also shown at the 1986 Experimental Aircraft Association Fly-In. In 1986, Cliff Robertson flew their reproduction No.21 while under tow behind a sports car, for the benefit of the press. Robertson said "We did a run and nothing happened. And we did a second run and nothing happened. Then the wind came up a little and we did another run and, sure enough, I got her up and flying. Then we went back and did a second one."
A second replica was built in Germany. On February 18, 1998, this was flown 500 m (1,600 ft) in Germany. The director of the aerospace department at the Deutsches Museum stated that such a replica was not proof that the original did actually fly, in that the 1998 reproduction used modern research and materials such as fibreglass, and had a modern engine.
Trotz aller Sorgfalt habe der flugfähige Nachbau der „Weißkopftaube“ leider 'keinerlei Beweiswert', kritisiert der Leiter der Luft- und Raumfahrtabteilung des Deutschen Museums, Werner Heinzerling. Beispielsweise wurden die Bambusholme der Tragflächen mit Glasfaserkunststoff verstärkt und anhand umfangreicher Tests – wie sie Weißkopf nicht möglich waren – der ideale Schwerpunkt der Maschine bestimmt. ... Auch die Verwendung moderner Flugmotoren verfälscht nach Ansicht des Aerodynamikers und Flughistorikers Heinzerling die historischen Tatsachen. [But despite of all diligence, the flyable reproduction of the Whitehead Dove was 'devoid of any conclusiveness', criticised Werner Heinzerling who is director of the aerospace department at Deutsches Museum. E.g. the bamboo beams of the wings had been enforced with fibre glass, and the aircraft's ideal centre of mass had been determined by extensive tests – which were not available to Weisskopf. ... Also the use of modern aircraft engines distorts the historical facts according to aerodynamics expert and aviation historian Heinzerling.]