Samuel Pierpont Langley became the third Secretary of the Smithsonian Institution in 1887. In 1891, he began experiments with large, tandem-winged models powered by small steam and gasoline engines he called aerodromes. After several failures with designs that were too fragile and under-powered to sustain themselves, Langley had his first genuine success on May 6, 1896, with his Aerodrome Number 5. It made the world's first successful flight of an unpiloted, engine-driven, heavier-than-air craft of substantial size. Two flights were made on May 6, one of 1,005 m (3,300 ft) and a second of 700 m (2,300 ft), at a speed of approximately 40 kph (25 mph). On November 28, 1896, another successful flight was made with a similar model, the Aerodrome Number 6. It was flown a distance of approximately 1,460 m (4,790 ft). In appearance, the Number 6 was much like the Number 5, except for having rounded wing tips.
Professor Samuel Pierpont Langley (1834-1906) was a leading scientific figure in the United States in the latter nineteenth century, well known especially for his astronomical research. He became the third Secretary of the Smithsonian Institution in 1887. Langley had begun serious investigation into heavier-than-air flight several years earlier while at the then Western University of Pennsylvania in Pittsburgh (now the University of Pittsburgh). He had erected a huge, 18.3 m (60 ft) diameter whirling arm at the university's Allegheny Observatory to perform aerodynamic research. At full speed, the tips of the whirling arm approached seventy miles per hour. Langley mostly ran tests with flat plates, but he also mounted small model airplanes he called aerostats, and even stuffed birds, on the arm. He also conducted an extensive series of experiments with rubber band-powered models.
Langley described these investigations and provided a summary of his results in Experiments in Aerodynamics, published in 1891. He then moved away from purely theoretical aerodynamic research, and began work aimed at engineering an actual flying machine. In 1891, he started to experiment with large, tandem-winged models powered by small steam and gasoline engines. Another large whirling arm, 9 m (29.5 ft) in diameter, was set up at the Smithsonian to test curved wing shapes and propellers, probably in connection with the design of these large powered models that Langley called aerodromes. After several failures with designs that were too fragile and under-powered to sustain themselves, Langley had his first genuine success with his Aerodrome No.5.
The No.5 had a metal tube-fuselage structure that housed the engine, the boiler, and other components of the propulsion system. The wings and tail were wood-frame, covered with fine silk. The power plant was a single-cylinder, one-horsepower steam engine equipped with a double-action piston with a slide valve, and a flashtube boiler fired by a pressure burner that vaporized gasoline. The engine drove twin propellers, centrally mounted between the front and rear sets of wings, through a system of shafts and bevel gears. The aircraft weighed approximately 11 kg (24.3 lb) ready for flight.
On May 6, 1896, Langley's Aerodrome No. 5 made the first successful flight of an unpiloted, engine-driven heavier-than-air craft of substantial size. It was launched from a spring-actuated catapult mounted on top of a houseboat on the Potomac River near Quantico, Virginia. Two flights were made that afternoon, one of 1,005 m (3,300 ft) and a second of 700 m (2,300 ft), at a speed of approximately 25 miles per hour. On both occasions, the Aerodrome No.5 landed in the water, as planned, because, in order to save weight, it was not equipped with landing gear.
On November 28, 1896, another successful flight was made with a similar model, the Aerodrome No.6. It was flown a distance of approximately 1,460 m (4,790 ft). The No.6 was actually Aerodrome No.4 greatly modified. The original No.4 had been so completely rebuilt between 1893 and 1895 that by then it was referred to as the "new No.4." It was radically altered again in the winter of 1895. This time so little remained of the original aircraft that it was given the new designation of Aerodrome No.6. In appearance, the No.6 was much like the No.5 except for having rounded wing tips. The No.5's wing tips were squared off.
The Aerodrome No.6 was transferred in 1905 from the research component of the Smithsonian to the United States National Museum, the entity of the Institution which at that time housed and cared for historical materials. The No.6 was restored for NASM by the University of Pittsburgh in 1978-1979. Since that time, it has been on loan to that institution and on display there.