First X-15 test pilot (for NAA) and major contributor to design and development in an engineering role.  Prior to the X-15 program Scott Crossfield had substantial test flight experience in the Bell X-1 and the Douglas D-558-2 Skyrocket. It is possible that no other test pilot in aviation history has test flown as many aircraft that are now displayed in flight museums -- The Smithsonian National Air and Space Museum's Milestones of Flight Gallery includes the #1 X-15 and the #2 Skyrocket, in which Crossfield became the first pilot to fly faster than Mach 2.  He also flew the #2 Bell X-1, the sister ship of the #1 ("Glamorous Glennis"), which also hangs in the same gallery.

Scott Crossfield's X-15 experience included 14 free flights, 2 captive carries, 14 aborts, and numerous ground tests.  Ground tests included the ammonia tank explosion that blew apart the #3 X-15 during an XLR-99 test run prior to first flight of this engine.  All of his flight test work was part of North American Aviation's initial test phase, which brought the X-15 to readiness for its official delivery to NASA and the Air Force.  This provided more than an average share of high adventure as early problems with aircraft systems were ironed out.  Although his role with North American Aviation precluded flying missions in the research program, Crossfield has said that he was very pleased to have been able to spend 9 years of his life with the X-15, from its conception to his last flight.

His distinguished career in test flight and aeronautical engineering has been widely recognized. He was one of 6 test pilots who were the founding members of the Society of Experimental Test Pilots (SETP), and his participation in that organization still continues. At his 80'th birthday, in 2001,  Scott Crossfield was still flying 200 hours per year as a private pilot.  His autobiography is the book Always Another Dawn, and the following references are but three of more than 1,000 citations on the web:

Biography, at NASA Dryden Flight Research Center
Biography, at Edwards AFB, Air Force Flight Test Center
Awards  --  AVweb's summary of Scott Crossfield's awards and recognitions