1.   Boeing was also involved in developing a supersonic airplane, but never built a prototype.

2.   A joke often heard around Lockheed Martin is that Boeing has never made a supersonic airplane.

3.   There was the atomic bomb, the first supersonic airplane flight, the introduction of penicillin, the dawn of television.

4.   Why else fly a supersonic airplane?

5.   Protests about noise, national rivalries and an oil crisis all played a part in killing the market for supersonic airplanes.