NASA Archives: NASA research pilot Milt Thompson standing alongside the X-15.

X-15 drop

A special alloy known as Inconel X gave the X-15 its distinctive black color. Made mostly of nickel with chromium, iron, and niobium (columbium), Inconel X was highly resistant to heat while maintaining its strength.

The "Q-Ball" in the nose of the X-15  served as an inertial flight data system capable of functioning in a highly dynamic pressure environment.  The 199 flights of the X-15 program gathered valuable data for the Mercury, Gemini, Apollo, and Space Shuttle programs. The X-15 pioneered new heat-resistant materials, as well as flight control systems that could transition between air and space.

During the 20th century, airplane design was driven by the mantra of “flying faster and higher.”