- X-15A-1 - 56-6670, 82 powered flights
- X-15A-2 - 56-6671, 53 powered flights
- X-15A-3 - 56-6672, 64 powered flights
- Joseph Albert Walker broke the highest altitude record of the time three times, his last on August 22, 1963. He reached 328 084 ft on his X-15.
- William J. "Pete" Knight broke the fastest speed record then on October 3, 1967. Knight reached a top speed of Mach 6.72 (6.72 times the speed of sound).
- X-15A-1 is on display in the National Air and Space Museum "Milestones of Flight" gallery
- X-15A-2 is on display in the National Museum of the United States Air Force's Research and Development hanger alongside other "X-planes"
- NB-52A is on display in the Pima Air and Space Museum
- NB-52B is at the Dryden Flight Research Center
- Neil Armstrong (first person to set foot on the moon) was one of the X-15 pilots
- The planned 200th flight of the X-15, piloted by William J. Knight was delayed six times due to technical problems and bad weather. It was eventually cancelled
Length: 50 ft 9 in (15.45 m)
Wingspan: 22 ft 4 in (6.8 m)
Height: 13 ft 6 in (4.12 m)
Wing area: 200 ft² (18.6 m²)
Empty weight: 14,600 lb (6,620 kg)
Loaded weight: 34,000 lb (15,420 kg)
Max takeoff weight: 34,000 lb (15,420 kg)
Powerplant: 1× Thiokol XLR99-RM-2 liquid-fuel rocket engine, 70,400 lbf at 30 km (313 kN)
Maximum speed: Mach 6.72 (4,520 mph / 7,274 km/h)
Range: 280 mi (450 km)
Service ceiling: 67 mi (354,330 ft / 108 km)
Rate of climb: 60,000 ft/min (18,288 m/min)
Wing loading: 170 lb/ft² (829 kg/m²)