In 1891 he built the first of his model Aerodromes as he called them, but they were constructed with steel frames, making the models to heavy to fly. For the next five years Langley doggedly kept building models, trying to solve the power-to-weight problem. Finally in 1896, he produced a steam-driven model---a sort of double monoplane with wings set in tandem---that flew for three quarters of a mile and then came down only because the fuel gave out.