Why did Boeing’s 2707, a jet designed to be bigger and faster than Concorde, never take off? What went wrong? Could we have been flying at supersonic speeds today if this project had succeeded?

Boeing's 2707 was only slightly more modest – Mach 2.7, 270 passengers, but a range of 6700 kilometres. In the head-to-head design competition the Boeing carried the day.

When the U.S. looked to build a supersonic airliner, the Lockheed L-2000 came within reach of becoming a commercial mainstay.