The #1 XB-70A (62-0001) is viewed from above in cruise configuration with the wing tips drooped for improved controllability. The XB-70A, capable of flying three times the speed of sound, was the world's largest experimental aircraft in the 1960s. Two XB-70A aircraft were built. Ship #1 was flown by the NASA Flight Research Center (now NASA Dryden), Edwards, Calif., in a high-speed flight research program.