 The Comet was powered by two race-tuned but otherwise standard production de Havilland Gipsy Six engines with a combined output of 460 hp (344 kW).This compares for example on the one hand to the single 180 hp engine fitted to the Junkers CL.I all-metal monoplane of 1918 and to the 1,172 hp Rolls-Royce Merlin C development engine which powered the prototype Spitfire in 1936.In the 1930s development of the jet engine began in Germany and in England.