North American X-15

The record-breaking North American X- 15 was an aircraft designed specifically to push flight to its extreme limits. From June 1959 to November 1968 it made 199 experimental flights, Flown by a dozen different test pilots, including future Moon-mission leader Neil Armstrong. The aim was to investigate the problems of flying at unprecedented speeds and at altitudes close to or beyond the edge of space.
Powered by a Reaction Motors single-barrel rocket motor, the X-15 had a simple basic configuration, with a tiny, unswept. tapering wing and a retractable undercarriage consisting of a nosewheel and two twin rear skids – the lower half of its ventral fin had to be jettisoned before it could land, to allow sufficient ground clearance.
Carried to around 40,000ft under the wing of a B-52 bomber, the X-15 was then released for a short but spectacular blast of rocket-driven flight. Its performance was truly incredible. The X-15 proved by far to be the fastest and highest -climbing aircraft that had ever been built.
The highest Speed attained was Mach 6.72 (4,534mph), on 3 October 1967. while highest-altitude missions officially qualified as space flights. The research programme was marred bv one fatal accident: on 15 November 1967 an X -15 broke up during its descent, killing lest pilot Michael J. Adams.