Professor Samuel Pierpont Langley (1834-1906) was 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. 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, he had success with Aerodrome No.5.

Samuel Langley Article