X-15

The museum displays the second X-15, tail number 66671, in its Research & Development Hangar. (66670, the first (and only other surviving) X-15 is displayed in the Milestones of Flight gallery at the National Air & Space Museum.)

This second X-15 was modified to the X-15A-2 configuration, which extended its fuselage and external tanks for an additional 60 seconds' worth of engine burn time.