Supersonic transport

A supersonic transport (SST) or a supersonic airliner is a civilian supersonic aircraft designed to transport passengers at speeds greater than the speed of sound. To date, the only SSTs to see regular service have been Concorde and the Tupolev Tu-144. The last passenger flight of the Tu-144 was in June 1978 and it was last flown in 1999 by NASA. Concorde's last commercial flight was in October 2003, with a November 26, 2003 ferry flight being its last airborne operation. Following the permanent cessation of flying by Concorde, there are no remaining SSTs in commercial service. Several companies have each proposed a supersonic business jet, which may bring supersonic transport back again. Supersonic airliners have been the objects of numerous recent and ongoing design studies. Drawbacks and design challenges are excessive noise generation (at takeoff and due to sonic booms during flight), high development costs, expensive construction materials, high fuel consumption, extremely high emissions, and an increased cost per seat over subsonic airliners. Despite these challenges, Concorde claimed it operated profitably. Throughout the 1950s an SST looked possible from a technical standpoint, but it was not clear if it could be made economically viable. Because of differences in lift generation, aircraft operating at supersonic speeds have approximately one-half the lift-to-drag ratio of subsonic aircraft. This implies that for any given required amount of lift, the aircraft will have to supply about twice the thrust, leading to considerably greater fuel use. This effect is pronounced at speeds close to the speed of sound, as the aircraft is using twice the thrust to travel at about the same speed. The relative effect is reduced as the aircraft accelerates to higher speeds. Offsetting this increase in fuel use was the potential to greatly increase sortie rates of the aircraft, at least on medium and long-range flights where the aircraft spends a considerable amount of time in cruise.