The rate of progress on the project was such that, within 15 months of design work having formally started, the first prototype, designated "M.D.450-01", had been fully constructed and had performed its maiden flight. On 28 February 1948, the first prototype of the "Ouragan" fighter conducted its first flight with Dassault Chief Test Pilot Kostia Rozanoff at the controls. This prototype lacked pressurization, armament, and the distinctive wingtip fuel tanks of subsequent production aircraft. It was powered by a Rolls-Royce Nene 102 centrifugal-flow engine capable of generating 22.27 kN (2,270 kp/5,000 lbf) of thrust. During service trials in 1949, the first prototype attained a top speed of 980 km/h (529 knots, 609 mph) and achieved an initial climb rate of 43 m/s (8,465 ft/min).