The W.1 engine was designed by Frank Whittle of Power Jets, and it produced 850 lbf. (3.78 kN) static trust (s.t.). Despite being underpowered, the airplane was still able to achieve an impressive speed of 338 mph (544 km/h). In further trials, the top speed was 370 mph (595 km/h) at 25,000 ft, (7,620 m) which was faster than the Spitfire. This was achieved by increasing the engine speed to 17,000 rpm, producing 1,000 lbf (4.44 kN) s.t.¹

    Although Frank Whittle of the United Kingdom and Hans von Ohain of Germany were simultaneously and independently working on the turbojet engine, Germany would be first in flight with jets with the introduction of the Heinkel He 178 on August 27, 1939. The next jet aircraft to take flight was the Gloster E.28/39 (G.40) on May 15, 1941. Both jets were powered by a single engine built for experimental purposes and not meant for production, although the E.28/39 design required provisions for possible later installment of armament.

    It was rare for a new plane to exceed design estimates, but that's exactly what happened. The second prototype did not fly until March 1943, but it was lost several months later due to a malfunction. Fortunately, the pilot bailed out and survived. As Power Jets improved its engine technology, a Whittle W.2B was installed in the E.28/39 and the aircraft achieved a top speed of 466 mph (750 km/h), making it faster than any contemporary fighter aircraft then in service. The sole surviving E.28/39 is in the Science Museum in London.