X-15A-3

American manned spaceplane. Cancelled 1962. It had been proposed that X-15 number 3 would be reworked to install a delta wing and designed to reach Mach 8.

The wing's leading edge would be of columbium, with Rene-41 alloy on the upper and lower surfaces. The rocketplane could have been air-launched from the top of an XB-70, but even when dropped from a subsonic B-52 would be capable of reaching Mach 8. The project was cancelled when X-15 number 3 was destroyed in a crash.

Spacecraft delta v: 2,400 m/s (7,800 ft/sec).