RELEVANCE TO THE X-15

The X-1, X-1A, and X-2 were precursors to the X-15 and were relevant to the future design of X-15, for the following reasons:

1) They were designed to be strictly research airplanes.

2) They were all powered by liquid-fuel rocket engines.

3) They were all air-launched. They were designed with no intention of ever evolving into viable military combat aircraft.

These research aircraft accomplished the first three steppingstones to high-speed flight: the X-1 to Mach 1, the X-1A to Mach 2.44, and the X-2 to Mach 3.2. The next phase was going to be huge, stepping into the regime of hypersonic flight. This was to be the role of the X-15.

▲ B-52 mother ship taking off with the X-15 mated under its wing. USAF,

Air Force Flight Test Center History Office, Edwards Air Force Base

▼ X-15 landing with an F-104 chase plane following close by. USAF, Air Force Flight Test Center History Office, Edwards Air Force Base