Around this same timeframe, the Air Ministry introduced a program of experimental aircraft to examine the effects of swept wings, as well as the delta wing configuration.[54] Furthermore, the Royal Air Force (RAF) identified a pair of proposed fighter aircraft equipped with swept wings from Hawker Aircraft and Supermarine, the Hawker Hunter and Supermarine Swift respectively, and successfully pressed for orders to be placed 'off the drawing board' in 1950.[55] On 7 September 1953, the sole Hunter Mk 3 (the modified first prototype, WB 188) flown by Neville Duke broke the world air speed record for jet-powered aircraft, attaining a speed of 727.63 mph (1,171.01 km/h) over Littlehampton, West Sussex.[56] This world record stood for less than three weeks before being broken on 25 September 1953 by the Hunter's early rival, the Supermarine Swift, being flown by Michael Lithgow.[57]