Langley Quarter-scale Aerodrome, 1903. Creator: Smithsonian Institution.

Model of the unpiloted, tandem-wing experimental aircraft built and tested by Samuel P. Langley, powered by a five-cylinder radial internal combustion gasoline engine of about 3.2 horsepower, turning two pusher propellers via geared transmission system. Samuel Langley's aeronautical experiments appeared to have concluded with the successful flights of his Aerodromes Number 5 and Number 6 in 1896, but privately he intended to build a full-sized, human-carrying airplane. Langley's simple approach was merely to scale up the unpiloted Aerodromes of 1896 to human-carrying proportions. The construction details and distribution of stresses on the Aerodrome A, as the full-sized version was called, were based on the successful performance of a gasoline-powered model, one-fourth the size. This exact scale miniature, known as the Quarter-scale Aerodrome, made two flights of 46 m (150 ft) and 108 m (350 ft) on June 18, 1901, powered by a five-cylinder radial internal combustion gasoline engine of about 3.2 horsepower.