Project X-15

1952–2005 · Planning, flights, records, losses

X-15 timeline: key milestones

The X-15 story in dates: how the program began, when it first flew, when each speed and altitude barrier fell, and how it ended. Each entry links to the page that covers it in depth.

1952–1958: Planning and construction

From a NACA recommendation to a rolled-out aircraft.

  1. Program

    NACA recommends hypersonic research

    The NACA Committee on Aerodynamics recommends more research toward Mach 10 and altitudes of 12 to 50 miles. Preliminary studies of space flight research follow in September.

    Origins
  2. Program

    Proposal goes to the Air Force and Navy

    After a NACA research airplane panel discusses the need in February, the proposal for a new hypersonic research aircraft is presented to the Air Force and the Navy.

    Origins
  3. Program

    Joint program agreed

    The memorandum of understanding between NACA, the Air Force and the Navy is signed, and the Air Force invites contractors to compete for the design.

    Origins
  4. Program

    North American Aviation wins the contract

    North American Aviation is selected to develop three X-15 aircraft.

    Origins
  5. Program

    XLR99 engine contract

    Reaction Motors receives the development contract for the XLR99 rocket engine.

    Aircraft
  6. Program

    Design frozen, construction starts

    The design configuration is set and construction begins, after a mock-up was completed in December 1956.

    Aircraft
  7. Program

    Rollout of the first X-15

    North American rolls out airplane No. 1 from the factory.

    Aircraft

1959–1961: Opening the envelope

Glide, powered flight and the XLR99, then Mach 4, 5 and 6 during 1961.

  1. Flight

    First flight: an unpowered glide

    Scott Crossfield flies airplane No. 1 on its first glide flight after release from the B-52.

    Flight profile
  2. Flight

    First powered flight

    Crossfield makes the first powered flight in airplane No. 2, using the interim XLR11 engines.

    Aircraft
  3. Flight

    First NASA flight

    Joe Walker makes the first flight in an X-15 by a NASA pilot.

    Pilots
  4. Flight

    First flight with the XLR99

    Crossfield flies airplane No. 2 with the XLR99, the throttleable engine that powers the remaining 175 flights.

    Aircraft
  5. Flight

    Neil Armstrong begins flying the X-15

    Armstrong flies seven X-15 flights between December 1960 and July 1962, before joining the astronaut corps.

    Pilots
  6. Record

    First flight to Mach 4

    The X-15 passes four times the speed of sound for the first time.

    Records
  7. Record

    First flight to Mach 5

    The X-15 reaches Mach 5.

    Records
  8. Record

    First flight above 200,000 ft

    An X-15 climbs past 200,000 ft for the first time.

    Records
  9. Record

    First flight to Mach 6

    Robert White takes the standard X-15 to Mach 6.04, the best speed it ever reached.

    Records
  10. Flight

    Third aircraft flies

    X-15-3 makes its first flight.

    Aircraft

1962–1964: Into space

The first flights above 300,000 ft, the altitude record and the 100th flight.

  1. Record

    First flight above 300,000 ft

    Robert White flies flight 62 to 59.6 miles, the first X-15 flight above 300,000 ft and beyond the 50-mile line.

    Records
  2. Flight

    Armstrong reaches Mach 5.74

    Neil Armstrong flies flight 64, his fastest X-15 flight, at Mach 5.74.

    Pilots
  3. Loss

    McKay crash-lands at Mud Lake

    Jack McKay survives a landing after an engine failure, but the gear collapses and he is seriously injured. X-15-2 is rebuilt as the X-15A-2.

    Accidents
  4. Record

    First flight above 100 km

    Joe Walker flies flight 90 to 347,800 ft, the first of two X-15 flights above the 100 km line.

    Records
  5. Record

    Altitude record: 354,200 ft

    Joe Walker flies flight 91 to 354,200 ft (67.1 miles), the highest altitude any X-15 reached.

    Records
  6. Program

    100th flight

    The program completes its 100th flight.

    Legacy
  7. Flight

    X-15A-2 flies

    The rebuilt aircraft, with a longer fuselage, drop tanks and an ablative coating, makes its first flight in the new configuration.

    Aircraft

1965–1968: Mach 6.7 and the last flights

The speed record, the loss of X-15-3 and the final mission.

  1. Loss

    Joe Walker killed in a formation collision

    Walker dies in a mid-air collision during a formation flight with an XB-70. It was not an X-15 flight.

    Pilots
  2. Record

    Speed record: Mach 6.7

    Pete Knight flies the X-15A-2 on flight 188 to Mach 6.7 (4,520 mph), the fastest speed ever recorded by a crewed, powered aircraft.

    Records
  3. Loss

    Flight 191 and the loss of Michael Adams

    X-15-3 breaks apart after a spin and an inverted dive. Michael Adams is killed. The aircraft is lost.

    Accidents
  4. Flight

    Final flight

    Bill Dana flies the 199th and last X-15 mission.

    Accidents
  5. Program

    Flight 200 cancelled

    A 200th flight planned for 21 November 1968 is cancelled on 20 December.

    Accidents

After the program

Recognition for the pilots.

  1. Record

    Astronaut wings for three NASA pilots

    Bill Dana, Jack McKay (posthumously) and Joe Walker receive astronaut wings for flying above 50 miles.

    Records

Dates and figures follow NASA's X-15 chronology and fact sheet, checked against the public flight list.

Sources