A common type of controllable-pitch propeller is hydraulically actuated; Frank W. Caldwell of the Hamilton Standard Division of the United Aircraft Company originally developed this design, which led to the award of the Collier Trophy of 1933. De Havilland subsequently bought up the rights to produce Hamilton propellers in the UK, while Rolls-Royce and Bristol Engines formed the British company Rotol in 1937 to produce their own designs. The French company of Pierre Levasseur and Smith Engineering Co. in the United States also developed controllable-pitch propellers. Wiley Post (1898-1935) used Smith propellers on some of his flights.