level cruising altitude sooner than any other passenger aircraft. It was later renamed the A300B. Perhaps the most significant change of the A300B was that it would not require new engines to be developed, being of a suitable size to be powered by Rolls-Royce's RB211, or alternatively the American Pratt & Whitney JT9D and General Electric CF6 powerplants; this switch was recognized as considerably reducing the project's development costs. To attract potential customers in the US market, it was decided that General Electric CF6-50 engines would power the A300 in place of the British RB207; these engines would be produced in co-operation with French firm Snecma. By this time, Rolls-Royce had been concentrating their efforts upon developing their RB211 turbofan engine instead and progress on the RB207's development had been slow for some time, the firm having suffered due to funding limitations, both of which had been factors in the engine switch decision. On 10 April 1969, a few months after the decision to drop the RB207 had been announced, the British government announced that they would withdraw from the Airbus venture. In response, West Germany proposed to France that they would be willing to contribute up to 50% of the project's costs if France was prepared to do the same. Additionally, the managing director of Hawker Siddeley, Sir Arnold Alexander Hall, decided that his company would remain in the project as a favoured sub-contractor, developing and manufacturing the wings for the A300, which would later become pivotal in later versions' impressive performance from short domestic to long intercontinental flights. Hawker Siddeley spent £35 million of its own funds, along with a further £35 million loan from the West German government, on the machine tooling to design and produce the wings. Programme launch On 29 May 1969, during the Paris Air Show, French transport minister Jean Chamant and German economics minister Karl Schiller signed an agreement officially launching the Airbus A300, the world's first twin-engine widebody airliner. The intention of the project was to produce an aircraft that was smaller, lighter, and more economical than its three-engine American rivals, the McDonnell Douglas DC-10 and the Lockheed L-1011 TriStar. In order to meet Air France's demands for an aircraft larger than 250-seat A300B, it was decided to stretch the fuselage to create a new variant, designated as the A300B2, which would be offered alongside the original 250-seat A300B, henceforth referred to