Boeing 2707

The Boeing 2707 was an American supersonic passenger transport project developed by Boeing during the 1960s in response to a United States government program intended to compete with the British-French Concorde and the Soviet Tupolev Tu-144. The original Boeing design used a variable-sweep wing that could change angle in flight, but escalating weight and cost problems forced a switch to a more conventional fixed delta wing configuration before any prototype was completed. Facing rising costs, environmental concerns over sonic booms, and doubts about its economic viability, the United States Congress voted to cut off funding in 1971, ending the program and leaving the Boeing 2707 as the best-known example of a supersonic airliner that never flew.