Knight joined the
United States Air Force in 1951. While only a
second lieutenant, he flew an
F-89 at the National Air Show in 1954 and won the Allison Jet Trophy. Starting in 1958, following his graduation from both U.S. Air Force Institute of Technology and the
Air Force Experimental Flight Test Pilot School (Class 58C), Knight served as a test pilot at
Edwards Air Force Base,
California. He was a project test pilot for the
F-100 Super Sabre,
F-101 Voodoo,
F-104 Starfighter and later,
T-38 Talon and
F-5 Freedom Fighter test programs. In 1960, he was one of six test pilots selected to fly the
X-20 Dyna-Soar, which was slated to become the first winged orbital space vehicle capable of lifting reentries and conventional landings. After the X-20 program was canceled in 1963, he completed the astronaut training curriculum through the
Aerospace Research Pilot School (Class 63A) at Edwards AFB and was selected to fly the
North American X-15. He had more than his share of eventful flights in the X-15. While climbing through at
Mach 4.17 on June 29, 1967, he suffered a total electrical failure and all onboard systems shut down. After reaching a maximum altitude of , he calmly set up a visual approach and, resorting to old-fashioned "seat-of-the-pants" flying, he glided down to a safe emergency landing at Mud Lake,
Nevada. For his remarkable feat of airmanship that day, he earned a
Distinguished Flying Cross. On October 3, 1967, Knight set a world aircraft speed record for manned aircraft by piloting the X-15A-2 to (
Mach 6.70), a record that still stands today. During 16 flights in the aircraft, Knight also became one of only five pilots to earn their
Astronaut Wings by flying an airplane in space, reaching an altitude of . After nearly ten years of test flying at Edwards AFB, he went to
Southeast Asia in 1968, where he completed a total of 253
combat missions in the
F-100 during the
Vietnam War. Following his combat tour, he served as test director during development of the
F-15 Eagle at
Wright Patterson Air Force Base in
Dayton, Ohio. He also was the program director for the International Fighter (F-5) Program at Wright-Patterson. In 1979, he returned to Edwards AFB, and served as a test pilot for the
F-16 Fighting Falcon. After 32 years of service and more than 6,000 hours in the cockpits of more than 100 different aircraft, he retired from the U.S. Air Force as a
colonel in 1982. ==Political career==