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. Highlighted in this image is the propeller of the Langley Quarter-scale Aerodrome.