View source for North American X-15

{{Redirect|X-15}}
{|{{Infobox aircraft begin
 |name= X-15
 |image= File:North American X-15.jpg|alt=Black rocket aircraft with stubby wings and short vertical stabilizers above and below tail unit
 |caption=
}}
{{Infobox aircraft type
 |type=Experimental high-speed [[Rocket-powered aircraft|rocket-powered]] research aircraft
 |manufacturer=North American Aviation
 |first flight=8 June 1959
 |introduced=17 September 1959
 |retired=December 1968
 |status=
 |primary user=United States Air Force
 |more users=[[NASA]]
 |produced=
 |number built= 3
 |unit cost=
 |developed from=
 |variants with their own articles=
}}
|}

The '''North American X-15''' was a [[Hypersonic speed|hypersonic]] [[rocket-powered aircraft]] operated by the United States Air Force and the [[NASA|National Aeronautics and Space Administration]] as part of the [[List of X-planes|X-plane]] series of experimental aircraft. The X-15 set speed and altitude records in the 1960s, reaching the [[Kármán line|edge of outer space]] and returning with valuable data used in aircraft and [[spacecraft]] design. {{As of|2015|9}}, the X-15 holds the [[Flight airspeed record|official world record]] for the highest speed ever recorded by a manned, powered aircraft. It could reach a top speed of {{convert|4520|mph|km/h|0}}, or Mach 6.72.<ref name="Fastest">{{cite web |url=http://www.aerospaceweb.org/aircraft/research/x15/ |title=North American X-15 High-Speed Research Aircraft |work=Aerospaceweb.org |year=2010 |accessdate=24 November 2008}}</ref><ref name="nasa20140228">{{cite web |url=http://www.nasa.gov/centers/armstrong/news/FactSheets/FS-052-DFRC.html |title=NASA Armstrong Fact Sheet: X-15 Hypersonic Research Program |publisher=NASA |editor-first=Yvonne |editor-last=Gibbs |date=28 February 2014 |accessdate=4 October 2015}}</ref>

During the X-15 program, 13 flights by eight pilots met the Air Force [[human spaceflight|spaceflight]] criterion by exceeding the altitude of {{convert|50|mi|km}}, thus qualifying these pilots as being [[astronaut]]s. The Air Force pilots qualified for astronaut wings immediately, while the civilian pilots were eventually awarded NASA [[astronaut wings]] in 2005, 35 years after the last X-15 flight.  The only Navy pilot in the X-15 program never took the aircraft above the requisite 50 mile altitude and so as a result, never earned himself astronaut wings.{{sfn|Jenkins|2001|p=10}}<ref name="NASA">{{cite press release |url=http://www.nasa.gov/home/hqnews/2005/aug/HQ_05233_X-15_pilots_honored.html |title=NASA Honors High Flying Space Pioneers |publisher=NASA |first1=Elvia H. |last1=Thompson |first2=Frederick A. |last2=Johnsen |date=23 August 2005 |id=Release 05-233}}</ref>

Of the 199 X-15 missions, two flights (both by [[Joseph A. Walker]]) qualified as true space flights per the international (''Fédération Aéronautique Internationale'') definition of a spaceflight by exceeding {{convert|100|km|mi|1|sp=us}} in altitude.

==Design and development==
[[File:X-15 in flight.jpg|thumb|right|X-15 after igniting rocket engine]]
[[File:X-15A2 NB-52B 3.jpg|thumb|right|X-15A2, with sealed ablative coating, external fuel tanks, and ramjet dummy test]]
The X-15 was based on a concept study from [[Walter Dornberger]] for the [[National Advisory Committee for Aeronautics]] (NACA) for a [[Hypersonic speed|hypersonic]] research aircraft.{{sfn|Käsmann|1999|p=105}} The [[RFP|requests for proposal]] were published on 30 December 1954 for the airframe and on 4 February 1955 for the [[rocket engine]]. The X-15 was built by two manufacturers: North American Aviation was contracted for the airframe in November 1955, and [[Reaction Motors]] was contracted for building the engines in 1956.

Like many [[X-plane|X-series]] aircraft, the X-15 was designed to be carried aloft and [[drop test|drop launched]] from under the wing of a NASA [[Boeing B-52 Stratofortress|B-52]] [[mother ship]].  Air Force NB-52A, "The High and Mighty One" (serial 52-0003, AKA ''Balls Three''), and NB-52B, "The Challenger"  (serial 52-0008, AKA ''[[Balls 8]]'') served as carrier planes for all X-15 flights.  Release took place at an altitude of about {{convert|8.5|mi|km}} and a speed of about {{convert|805|km/h|mph|disp=flip|sp=us}}.<ref name="E-4942">{{cite web |url=http://www.dfrc.nasa.gov/Gallery/Photo/X-15/HTML/E-4942.html |title=X-15 launch from B-52 mothership |publisher=Armstrong Flight Research Center |date=6 February 2002 |id=Photo E-4942}}</ref> The X-15 fuselage was long and cylindrical, with rear fairings that flattened its appearance, and thick, dorsal and ventral wedge-fin stabilizers. Parts of the fuselage were heat-resistant nickel alloy ([[Inconel]]-X 750).{{sfn|Käsmann|1999|p=105}} The retractable landing gear comprised a nose-wheel carriage and two rear skids. The skids did not extend beyond the ventral fin, which required the pilot to jettison the lower fin (fitted with a parachute) just before landing.

===Cockpit and pilot systems===
[[File:North American X-15A-2 cockpit 2 USAF.jpg|thumb|left|Cockpit of an X-15]]
The X-15 was a research program and changes were made to various systems over the course of the program and between the different models. The X-15 was operated under several different scenarios including attachment to a launch aircraft, drop, main engine start and acceleration, a ballistic flight into thin air/space, re-entry into thicker air, and an unpowered glide to landing. Alternatively, if the main engine was not started the pilot went directly to a landing. The main rocket engine operated only for a relatively short part of the flight, but was capable of boosting the X-15 to its high speeds and altitudes. Without main engine thrust, the X-15's instruments and control surfaces remained functional, but the aircraft could not maintain altitude.

Because the X-15 also had to be controlled in an environment where there was too little air for aerodynamic [[flight control surface]]s, it had a [[reaction control system]] (RCS) that used rocket thrusters.<ref name=paul/> There were two different X-15 pilot control setups: one used three joysticks; the other, one joystick.<ref name=jarvis/>

The X-15 type with multiple control sticks for the pilot included a traditional rudder and stick, and another joystick on the left which sent commands to the reaction control system.<ref name=paul2/> A third joystick on the right side was used during high-G maneuvers to augment the center stick.<ref name=paul2/> In addition to pilot input, the X-15 "[[Stability Augmentation System]]" (SAS) sent inputs to the aerodynamic controls to help the pilot maintain attitude control.<ref name=paul2/>  The reaction control system could be operated in two modes, manual and automatic.<ref name=jarvis/> The automatic mode used a feature called "Reaction Augmentation System" (RAS) that helped stabilize the vehicle at high altitude.<ref name=jarvis>{{cite book |url=http://www.nasa.gov/centers/dryden/pdf/87709main_H-364.pdf |title=Operational Experience With the X-15 Reaction Control and Reaction Augmentation Systems |publisher=NASA |first1=Calvin R. |last1=Jarvis |first2=Wilton P. |last2=Lock |year=1965 |id=TN D-2864 |oclc=703664750}}</ref>  The RAS was typically used for approximately three minutes of an X-15 flight before automatic power off.<ref name=jarvis/>

The second setup used the MH-96 flight control system which allowed one joystick in place of three and simplified pilot input.<ref name=goleta>{{cite web |url=http://www.air-and-space.com/x-15%20forty%20years%20later%20200202.htm |title=Forty Years ago in the X-15 Flight Test Program, November 1961–March 1962 |publisher=Goleta Air & Space Museum |accessdate=3 October 2011}}</ref> The MH-96 could automatically blend aerodynamic and rocket controls depending on how effective each system was at controlling the aircraft.<ref name=goleta/>

Among the many controls were the rocket engine throttle and a control for jettisoning the ventral tail fin.<ref name=paul2/> Other features of the cockpit were heated windows to prevent icing, and a forward headrest for periods of high deceleration.<ref name=paul2/>

The X-15 had an ejection seat that allowed ejection at speeds up to Mach 4 and/or {{convert|120000|ft|km}} altitude, although it was not used during the program.<ref name=paul2>{{cite web |url=http://www.sierrafoot.org/x-15/pirep2.html |title=X-15 Pilot Report, Part 2: X-15 Cockpit Check |work=SierraFoot.org |first=Paul |last=Raveling |accessdate=1 October 2011}}</ref> In the event of ejection, the seat had deployable fins which were used until it reached a safer speed/altitude, where it could deploy its main parachute.<ref name=paul2/> Pilots wore a pressure suit, which could be pressurized with nitrogen gas.<ref name=paul2/> Above {{convert|35000|ft|km}} altitude, the cockpit was pressurized to {{convert|3.5|psi|atm|abbr=on}} with nitrogen gas, and oxygen for breathing was fed separately to the pilot.<ref name=paul2/>

===Propulsion===
[[File:North American X-15 Nozzle.jpg|thumb|right|X-15 tail with XLR-99]]
Early flights used two [[Reaction Motors XLR11]] [[liquid-propellant rocket]] engines. Later flights were undertaken with a single [[Reaction Motors XLR99|XLR99]] rocket engine generating {{convert|57000|lb-f|kN}} of thrust. The XLR11 used [[ethyl alcohol]] and liquid oxygen. The XLR99 engine used anhydrous ammonia and liquid oxygen as propellant, and hydrogen peroxide to drive the high-speed turbopump that delivered propellants to the engine.<ref name=paul/> It could burn {{convert|15000|lb|kg|0}} of propellant in 80 seconds.<ref name=paul/> The XLR99s could be throttled, and were the first such controllable engines that were [[Human-rating certification|man-rated]].

The X-15 [[reaction control system]] (RCS), for maneuvering in low-pressure/density environment, used [[high-test peroxide]] (HTP), which decomposes into water and oxygen in the presence of a catalyst and could provide a [[specific impulse]] of 140 seconds.<ref name="jarvis" />{{sfn|Davies|2003|p=8.28}} The HTP also fueled a turbopump for the main engines and auxiliary power units (APUs).<ref name=paul>{{cite web |url=http://www.sierrafoot.org/x-15/pirep1.html |title=X-15 Pilot Report, Part 1: X-15 General Description & Walkaround |work=SierraFoot.org |first=Paul |last=Raveling |accessdate=30 September 2011}}</ref> Additional tanks for helium and liquid nitrogen performed other functions, for example the fuselage interior was purged with helium gas, and the liquid nitrogen was used as coolant for various systems.<ref name=paul/>

===Wedge tail and hypersonic stability===
[[File:X-15 and B-52 Mother ship.jpg|thumb|X-15 attached to its B-52 mother ship with a T-38 flying nearby]]
The X-15 had a thick wedge tail to enable it to fly in a steady manner at hypersonic speeds.<ref name=wendell>{{cite book |url=http://www.hq.nasa.gov/office/pao/History/SP-60/cover.html |title=X-15 Research Results: With a Selected Bibliography |publisher=NASA |first=Wendell H. |last=Stillwell |year=1965 |id=NASA SP-60 |oclc=44275779}}</ref> This produced a significant amount of drag at lower speeds;<ref name=wendell/> the blunt end at the rear of the X-15 could produce as much drag as an entire [[Lockheed F-104 Starfighter|F-104 Starfighter]].<ref name=wendell/>
{{quotation|A wedge shape was used because it is more effective than the conventional tail as a stabilizing surface at hypersonic speeds. A vertical-tail area equal to 60 percent of the wing area was required to give the X-15 adequate directional stability.|Wendell H. Stillwell|[http://history.nasa.gov/SP-60/ch-3.html X-15 Research Results (SP-60)]}}
Stability at hypersonic speeds was aided by side panels which could be extended out from the tail to increase the overall surface area, and these panels doubled as air-brakes.<ref name=wendell/>

==Operational history==
[[File:Pilot Neil Armstrong with X-15 -1 (9458061153).jpg|thumb|upright|[[Neil Armstrong]] with X-15 number 1]]
[[File:X-15 Pilots - GPN-2000-000143.jpg|thumb|275px|Members of the X-15 flight crew, left to right: Engle, Rushworth, McKay, Knight, Thompson, and Dana.]]
Altitudes attained by X-15 aircraft do not match those of [[Alan Shepard]]'s and [[Gus Grissom]]'s [[Project Mercury]] space capsules in 1961, nor of any other manned [[spacecraft]]. However, the X-15 ranks supreme among manned rocket-powered aircraft, becoming the world's first operational [[spaceplane]] in the early 1960s.

Before 1958, United States Air Force (USAF) and [[NACA]] officials discussed an orbital X-15 [[spaceplane]], the '''X-15B''' that would launch into [[outer space]] from atop an [[SM-64 Navaho]] missile.  This was canceled when the NACA became [[NASA]] and adopted [[Project Mercury]] instead.

By 1959, the [[Boeing X-20 Dyna-Soar]] space-glider program was to become the USAF's preferred means for launching military manned spacecraft into orbit. This program was canceled in the early 1960s before an operational vehicle could be built.{{sfn|Jenkins|2001|p=10}}  Various configurations of the Navajo were considered, and another proposal involved a Titan I stage.<ref name=wade/>

Three X-15s were built, flying 199 test flights, the last on 24 October 1968.

The first X-15 flight was a captive-carry unpowered test by [[Scott Crossfield]], on 8 June 1959. Crossfield also piloted the first powered flight, on 17 September 1959, and his first flight with the XLR-99 [[rocket engine]] on 15 November 1960. Twelve test pilots flew the X-15. Among these were [[Neil Armstrong]], later a NASA [[astronaut]] and first man to set foot on the Moon, and [[Joe Engle]], later a commander of [[Space Shuttle program|NASA Space Shuttle]] test flights.

In a 1962 proposal, NASA considered using the B-52/X-15 as a launch platform for a [[Blue Scout]] rocket to place satellites weighing up to {{convert|150|lb|kg}} into orbit.<ref name="wade">{{cite web |url=http://www.astronautix.com/lvs/x15scout.htm |title=X-15/Blue Scout |work=Encyclopedia Astronautica |first=Mark |last=Wade |accessdate=30 September 2011}}</ref><ref name="cis20120321">{{cite web |url=http://www.citizensinspace.org/2012/03/historical-note-blue-scout-x-15/ |title=Historical note: Blue Scout / X-15 |work=Citizensinspace.org |date=21 March 2012}}</ref>

In July and August 1963, pilot [[Joseph A. Walker]] exceeded {{nowrap|100 km}} in altitude, joining NASA astronauts and Soviet cosmonauts as the first human beings to cross that line on their way to [[outer space]].  The USAF awarded [[astronaut wings]] to anyone achieving an altitude of {{convert|50|mi|km}}, while the FAI set the [[Kármán line|limit of space]] at {{convert|100|km|mi|1|sp=us}}.

On 15 November 1967, U.S. Air Force test pilot Major [[Michael J. Adams]] was killed during [[X-15 Flight 3-65-97|X-15 Flight 191]] when the X-15-3, AF Ser. No. 56-6672, entered a hypersonic spin while descending, then oscillated violently as aerodynamic forces increased after re-entry. As his aircraft's flight control system operated the control surfaces to their limits, acceleration built to 15 ''g'' vertical and 8.0 ''g'' lateral.  The airframe broke apart at {{convert|60000|ft|km}} altitude, scattering the X-15's wreckage for {{convert|50|sqmi|km2}}.  On 8 May 2004, a monument was erected at the cockpit's locale, near [[Randsburg, California]].<ref name="xpress2004">{{cite journal |url=http://www.nasa.gov/centers/dryden/news/X-Press/stories/2004/073004/ppl_adams.html |title=Michael Adams: Remembering a Fallen Hero |journal=The X-Press |first=Peter W. |last=Merlin |volume=46 |issue=6 |date=30 July 2004}}</ref> Major Adams was posthumously awarded Air Force astronaut wings for his final flight in X-15-3, which had reached an altitude of {{convert|81.1|km|mi|disp=flip|sp=us}}. In 1991, his name was added to the [[Space Mirror Memorial|Astronaut Memorial]].<ref name="xpress2004" />

The second X-15A was rebuilt after a landing accident. It was lengthened by {{Convert|2.4|ft|m}}, had a pair of auxiliary fuel tanks attached beneath its fuselage and wings, and a complete heat-resistant ablative coating was added. The plane was renamed the '''X-15A-2''', and took flight for the first time on 28 June 1964. It reached its maximum speed of {{convert|7274|km/h|mph|disp=flip|sp=us}} in October 1967 with pilot [[William "Pete" Knight]] of the U.S. Air Force in control.

Five aircraft were used during the span of the X-15 program:  three X-15s planes and two [[Boeing B-52 Stratofortress|B-52]] bombers:
*{{nowrap|'''X-15A''' –}} ''56-6670'', 82 powered flights
*{{nowrap|'''X-15A (later X-15A-2)''' –}} ''56-6671'', 31 powered flights as X-15A, 22 powered flights as X-15A-2, and 53 in total
*{{nowrap|'''X-15A''' –}} ''56-6672'', 64 powered flights
*{{nowrap|'''NB-52A''' –}} ''52-003'' (retired in October 1969)
*{{nowrap|'''NB-52B''' –}} ''[[Balls 8|52-008]]'' (retired in November 2004)

A 200th flight over Nevada was first scheduled for 21 November 1968, to be flown by William "Pete" Knight. Numerous technical problems and outbreaks of bad weather delayed this proposed flight six times, and it was permanently canceled on 20 December 1968. This X-15 was detached from the B-52 and then put into indefinite storage. The aircraft was later donated to the [[National Museum of the United States Air Force|Air Force Museum]] at Wright-Patterson Air Force Base for display.

<gallery widths="180px">
File:Boeing NB-52A carrying X-15.jpg|NB-52A (s/n 52-003), permanent test variant, carrying an X-15, with mission markings; horizontal X-15 silhouettes denote glide flights, diagonal silhouettes denote powered flights.
File:X-15 launched bw.jpg|X-15 just after release.
File:NorthAmericanX-15600.jpeg|X-15 touching down on its skids, with the lower ventral fin jettisoned.
File:X15A2 with tanks.jpg|X-15A2 (56-6671) with external fuel tanks
</gallery>

==Current static displays==
[[File:North American X-15 National Air and Space Museum photo D Ramey Logan.jpg|thumb|X-15 at the National Air and Space Museum in Washington, D.C.]]

*X-15A-1 (AF Ser. No. 56-6670) is on display in the [[National Air and Space Museum]] "Milestones of Flight" gallery, Washington, D.C.
*X-15A-2 (AF Ser. No. 56-6671) is at the [[National Museum of the United States Air Force]], at Wright-Patterson Air Force Base, near Dayton, Ohio. It was retired to the museum in October 1969.{{sfn|USAF Museum Guidebook|1975|p=73}} The aircraft is displayed in the museum's Research and Development Gallery alongside other "X-planes", including the [[Bell X-1| Bell X-1B]] and [[Douglas X-3 Stiletto]].

===Mockups===
*[[Dryden Flight Research Center]], Edwards AFB, California, USA (painted with AF Ser. No. 56-6672)
*[[Pima Air & Space Museum]], adjacent to [[Davis-Monthan AFB]], Tucson, Arizona (painted with AF Ser. No. 56-6671)
*[[Evergreen Aviation & Space Museum]], McMinnville, Oregon (painted with AF Ser. No. 56-6672). A full-scale wooden mockup of the X-15, it is displayed along with one of the rocket engines.

===Stratofortress mother ships===
[[File:Boeing NB-52B takeoff 061127-F-1234S-007.jpg|thumb|right|NB-52B takes off with an X-15]]
*NB-52A (AF Ser. No. 52-0003) is displayed at the [[Pima Air & Space Museum]] adjacent to [[Davis–Monthan Air Force Base|Davis–Monthan AFB]] in Tucson, Arizona. It launched the X-15-1 30 times, the X-15-2, 11 times, and the X-15-3 31 times (as well as the [[Northrop M2-F2|M2-F2]] four times, the [[Northrop HL-10|HL-10]] 11 times and the [[Martin Marietta X-24A|X-24A]] twice).
*NB-52B (AF Ser. No. [[Balls 8|52-0008]]) is on permanent display outside the north gate of Edwards AFB, California. It launched the majority of X-15 flights.

==Record flights==

===Highest flights===
The FAI set the [[Kármán line|limit of space]] at {{convert|100|km|mi|1|sp=us}}. But in the 1960s, the U.S. Air Force considered an altitude of {{convert|50|mi|km}} as the limit of space; U.S. Air Force and NASA pilots and crew exceeding that altitude at the time could be awarded the [[astronaut badge]]. Thirteen X-15 flights went higher than 50 miles, two of which exceeded 100 kilometers.

{| class="wikitable sortable"
|+ X-15 flights higher than 50 miles in chronological order
|- style="background:#efefef;"
! Flight
! Date
! Top speed
! Altitude
! Pilot
|-
| Flight 62
| 17 July 1962
|align="right"| {{convert|3831|mph|km/h|abbr=on}}
|align="right"| {{convert|59.6|mi|km|abbr=on}}
| [[Robert Michael White|Robert M. White]]
|-
| Flight 77
| 17 January 1963
|align="right"| {{convert|3677|mph|km/h|abbr=on}}
|align="right"| {{convert|51.4|mi|km|abbr=on}}
| [[Joseph A. Walker]]
|-
| Flight 87
| 27 June 1963
|align="right"| {{convert|3425|mph|km/h|abbr=on}}
|align="right"| {{convert|53.9|mi|km|abbr=on}}
| [[Robert A. Rushworth]]
|-
| '''[[X-15 Flight 90|Flight 90]]'''
| 19 July 1963
|align="right"| {{convert|3710|mph|km/h|abbr=on}}
|align="right"| {{convert|65.8|mi|km|abbr=on}}
| Joseph A. Walker
|-
| '''[[X-15 Flight 91|Flight 91]]'''
| 22 August 1963
|align="right"| {{convert|3794|mph|km/h|abbr=on}}
|align="right"| {{convert|67.0|mi|km|abbr=on}}
| Joseph A. Walker
|-
| Flight 138
| 29 June 1965
|align="right"| {{convert|3431|mph|km/h|abbr=on}}
|align="right"| {{convert|53.1|mi|km|abbr=on}}
| [[Joe Engle|Joseph H. Engle]]
|-
| Flight 143
| 10 August 1965
|align="right"| {{convert|3549|mph|km/h|abbr=on}}
|align="right"| {{convert|51.3|mi|km|abbr=on}}
| Joseph H. Engle
|-
| Flight 150
| 28 September 1965
|align="right"| {{convert|3731|mph|km/h|abbr=on}}
|align="right"| {{convert|55.9|mi|km|abbr=on}}
| [[John B. McKay]]
|-
| Flight 153
| 14 October 1965
|align="right"| {{convert|3554|mph|km/h|abbr=on}}
|align="right"| {{convert|50.4|mi|km|abbr=on}}
| Joseph H. Engle
|-
| Flight 174
| 1 November 1966
|align="right"| {{convert|3750|mph|km/h|abbr=on}}
|align="right"| {{convert|58.1|mi|km|abbr=on}}
| [[William H. "Bill" Dana]]
|-
| Flight 190
| 17 October 1967
|align="right"|  {{convert|3856|mph|km/h|abbr=on}}
|align="right"| {{convert|53.1|mi|km|abbr=on}}
| [[William J. "Pete" Knight]]
|-
| [[X-15 Flight 191|Flight 191]]
| 15 November 1967
|align="right"|  {{convert|3569|mph|km/h|abbr=on}}
|align="right"| {{convert|50.3|mi|km|abbr=on}}
| [[Michael J. Adams]]<sup>†</sup>
|-
| Flight 197
| 21 August 1968
|align="right"| {{convert|3443|mph|km/h|abbr=on}}
|align="right"| {{convert|50.6|mi|km|abbr=on}}
| William H. Dana
|}<sup>†</sup> fatal

===Fastest recorded flights===
[[File:X15 speed altitude.jpg|thumb|300px|Key speed and altitude benchmarks of the X-15.]]
{| class="wikitable sortable"
|+ X-15 ten fastest flights
|- style="background:#efefef;"
! Flight
! Date
! Top Speed
! Altitude
! Pilot
|-
| Flight 45
| 9 November 1961
|align="right"| {{convert|4092|mph|km/h|abbr=on}}
|align="right"| {{convert|19.2|mi|km|abbr=on}}
| [[Robert Michael White|Robert M. White]]
|-
| Flight 59
| 27 June 1962
|align="right"| {{convert|4104|mph|km/h|abbr=on}}
|align="right"| {{convert|23.4|mi|km|abbr=on}}
| [[Joseph A. Walker]]
|-
| Flight 64
| 26 July 1962
|align="right"| {{convert|3989|mph|km/h|abbr=on}}
|align="right"| {{convert|18.7|mi|km|abbr=on}}
| [[Neil Armstrong|Neil A. Armstrong]]
|-
| Flight 86
| 25 June 1963
|align="right"| {{convert|3910|mph|km/h|abbr=on}}
|align="right"| {{convert|21.7|mi|km|abbr=on}}
| Joseph A. Walker
|-
| Flight 89
| 18 July 1963
|align="right"| {{convert|3925|mph|km/h|abbr=on}}
|align="right"| {{convert|19.8|mi|km|abbr=on}}
| [[Robert A. Rushworth]]
|-
| Flight 97
| 5 December 1963
|align="right"| {{convert|4017|mph|km/h|abbr=on}}
|align="right"| {{convert|19.1|mi|km|abbr=on}}
| Robert A. Rushworth
|-
| Flight 105
| 29 April 1964
|align="right"| {{convert|3905|mph|km/h|abbr=on}}
|align="right"| {{convert|19.2|mi|km|abbr=on}}
| Robert A. Rushworth
|-
| Flight 137
| 22 June 1965
|align="right"| {{convert|3938|mph|km/h|abbr=on}}
|align="right"| {{convert|29.5|mi|km|abbr=on}}
| [[John B. McKay]]
|-
| Flight 175
| 18 November 1966
|align="right"| {{convert|4250|mph|km/h|abbr=on}}
|align="right"| {{convert|18.7|mi|km|abbr=on}}
| [[William J. "Pete" Knight]]
|-
| Flight 188
| 3 October 1967
|align="right"| {{convert|4519|mph|km/h|abbr=on}}
|align="right"| {{convert|19.3|mi|km|abbr=on}}
| William J. "Pete" Knight
|}

==X-15 pilots==
{| class="wikitable"
! colspan="8"|X-15 pilots and their achievements during the program
|-
! Pilot
! Organization
! Total<br />Flights
! USAF<br />space<br />flights
! FAI<br />space<br />flights
! Max<br />Mach
! Max<br />speed<br />(mph)
! Max<br />altitude<br />(miles)
|-
| [[Michael J. Adams]]<sup>†</sup>
| U.S. Air Force
|align="center"| 7
|align="center"| 1
|align="center"| 0
|align="center"| 5.59
|align="right"| 3,822
|align="right"| 50.3
|-
| [[Neil Armstrong]]
| NASA
|align="center"| 7
|align="center"| 0
|align="center"| 0
|align="center"| 5.74
|align="right"| 3,989
|align="right"| 39.2
|-
| [[Albert Scott Crossfield|Scott Crossfield]]
| North American Aviation
|align="center"| 14
|align="center"| 0
|align="center"| 0
|align="center"| 2.97
|align="right"| 1,959
|align="right"| 15.3
|-
| [[William H. "Bill" Dana]]
| NASA
|align="center"| 16
|align="center"| 2
|align="center"| 0
|align="center"| 5.53
|align="right"| 3,897
|align="right"| 58.1
|-
| [[Joe Engle|Joseph H. Engle]]
| U.S. Air Force
|align="center"| 16
|align="center"| 3
|align="center"| 0
|align="center"| 5.71
|align="right"| 3,887
|align="right"| 53.1
|-
| [[William J. "Pete" Knight]]
| U.S. Air Force
|align="center"| 16
|align="center"| 1
|align="center"| 0
|align="center"| 6.70
|align="right"| 4,519
|align="right"| 53.1
|-
| [[John B. McKay]]
| NASA
|align="center"| 29
|align="center"| 1
|align="center"| 0
|align="center"| 5.65
|align="right"| 3,863
|align="right"| 55.9
|-
| [[Forrest S. Petersen]]
| U.S. Navy
|align="center"| 5
|align="center"| 0
|align="center"| 0
|align="center"| 5.3
|align="right"| 3,600
|align="right"| 19.2
|-
| [[Robert A. Rushworth]]
| U.S. Air Force
|align="center"| 34
|align="center"| 1
|align="center"| 0
|align="center"| 6.06
|align="right"| 4,017
|align="right"| 53.9
|-
| [[Milton Orville Thompson|Milton O. Thompson]]
| NASA
|align="center"| 14
|align="center"| 0
|align="center"| 0
|align="center"| 5.48
|align="right"| 3,723
|align="right"| 40.5
|-
| [[Joseph A. Walker]]
| NASA
|align="center"| 25
|align="center"| 3
|align="center"| 2
|align="center"| 5.92
|align="right"| 4,104
|align="right"| 67.0
|-
| [[Robert Michael White|Robert M. White]]<sup>**</sup>
| U.S. Air Force
|align="center"| 16
|align="center"| 1
|align="center"| 0
|align="center"| 6.04
|align="right"| 4,092
|align="right"| 59.6
|-
| align="center" colspan="8"|<sup>†</sup> Killed in the crash of an X - 15 <br/><sup>**</sup> White was the back-up pilot for Captain [[Iven Carl Kincheloe, Jr.|Iven Kincheloe]], who was killed in a F-104A.
|}

==Specifications (X-15)==
[[File:North American X-15 3-view.svg|right|400px|X-15 3-view]]
Other configurations include the [[Reaction Motors XLR11]] equipped X-15, and the long version.

{{aircraft specifications
|plane or copter?=plane
|jet or prop?=jet
|ref=
|crew=one
|capacity=
|payload main=
|payload alt=
|length main=50 ft 9 in
|length alt=15.45 m
|span main=22 ft 4 in
|span alt=6.8 m
|height main=13 ft 6 in
|height alt=4.12 m
|area main=200 ft<sup>2</sup>
|area alt=18.6 m<sup>2</sup>
|airfoil=
|empty weight main=14,600 lb
|empty weight alt=6,620 kg
|loaded weight main=34,000 lb
|loaded weight alt=15,420 kg
|useful load main=
|useful load alt=
|max takeoff weight main=34,000 lb
|max takeoff weight alt=15,420 kg
|more general=
|engine (jet)=[[Reaction Motors XLR99]]-RM-2
|type of jet=liquid propellant rocket engine
|number of jets=1
|thrust main=70,400 lb<sub>f</sub> at 30&nbsp;km
|thrust alt=313 kN
|thrust original=
|afterburning thrust main=
|afterburning thrust alt=
|max speed main=4,520 mph
|max speed alt=7,274&nbsp;km/h
|cruise speed main=
|cruise speed alt=
|stall speed main=
|stall speed alt=
|never exceed speed main=
|never exceed speed alt=
|range main=280 mi
|range alt=450&nbsp;km
|ceiling main=67 mi
|ceiling alt=108&nbsp;km, 354,330 ft
|climb rate main=60,000 ft/min
|climb rate alt=18,288 m/min
|loading main=170 lb/ft<sup>2</sup>
|loading alt=829 kg/m<sup>2</sup>
|thrust/weight=2.07
|power/mass main=
|power/mass alt=
|more performance=
|armament=
|avionics=
}}

==See also==
{{aircontent|
|related=
|similar aircraft=
*[[Bell X-2]]
*[[Douglas D-558-2 Skyrocket]]
|sequence=
|lists=
*[[List of rocket aircraft]]
*[[List of X-15 flights]]
*[[List of spaceflight-related accidents and incidents]]
}}

==References==
;Notes
{{Reflist|colwidth=35em}}

;Bibliography
{{Refbegin}}
* {{cite book |url=https://books.google.com/books?id=lkSM9rmWQBgC&pg=SA8-PA28&lpg=SA8-PA28&dq=hydrazine+X-15 |title=The Standard Handbook for Aeronautical and Astronautical Engineers |publisher=McGraw-Hill |location=New York |editor-first=Mark |editor-last=Davies |pages=8–28 |year=2003 |isbn=978-0-07-136229-0 |ref=harv}}
* {{cite book |title=X-15: The NASA Mission Reports |publisher=Apogee Books |location=Burlington, Ontario |editor-first=Robert |editor-last=Godwin |year=2001 |isbn=1-896522-65-3 |ref=harv}}
* {{cite book |chapter=Saga of the Rocket Ships |title=Air Enthusiast Six |publisher=Pilot Press |location=Bromley, Kent, UK |first=Richard P. |last=Hallion |editor1-first=William |editor1-last=Green |editor2-first=Gordon |editor2-last=Swanborough |date=March–June 1978 |ref=harv}}
* {{cite book |title=Space Shuttle: The History of the National Space Transportation System: The First 100 Missions |edition=3rd |publisher=Voyageur Press |location=Stillwater, Minnesota |first=Dennis R. |last=Jenkins |year=2001 |isbn=0-9633974-5-1 |ref=harv}}
* {{cite book |url=http://history.nasa.gov/monograph31.pdf |title=American X-Vehicles: An Inventory—X-1 to X-50 |series=Monographs in Aerospace History No. 31 |publisher=NASA |first1=Dennis R. |last1=Jenkins |first2=Tony |last2=Landis |first3=Jay |last3=Miller |date=June 2003 |id=SP-2003-4531 |oclc=68623213 |ref=harv}}
* {{cite book |url=http://www.aeronautics.nasa.gov/ebooks/downloads/X_15_Frontier_of_Flight.pdf |title=X-15: Extending the Frontiers of Flight |publisher=NASA |first=Dennis R. |last=Jenkins |year=2007 |isbn=9780160792854 |ref=harv}}
* {{cite book |title=Die schnellsten Jets der Welt: Weltrekord-Flugzeuge |trans_title=The Fastest Jets in the World: World Record Aircraft |publisher=Aviatic Verlag |location=Kolpingring, Germany |language=German |first=Ferdinand C. W. |last=Käsmann |year=1999 |isbn=3-925505-26-1 |ref=harv}}
* {{cite book |url=http://www.sierrafoot.org/x-15/documents/nasa_cr-82003.html |title=Design Report - Thermal Protection System, X-15A-2 |publisher=Martin Marietta Corporation |location=Denver, Colorado |first=A. B. |last=Price |date=12 January 1968 |id=NASA CR-82003 |ref=harv}}
* {{cite book |title=At the Edge of Space: The X-15 Flight Program |publisher=Smithsonian Institution Press |location=Washington, D.C. |first=Milton O. |last=Thompson |year=1992 |isbn=1-56098-107-5 |ref=harv}}
* {{cite book |title=X-15 Diary: The Story of America's First Space Ship |publisher=iUniverse |location=Lincoln, Nebraska |first=Richard |last=Tregaskis |year=2000 |isbn=0-595-00250-1 |ref=harv}}
* {{cite book |title=United States Air Force Museum Guidebook |publisher=Air Force Museum Foundation |location=Wright-Patterson AFB, Ohio |year=1975 |ref={{harvid|USAF Museum Guidebook|1975}}}}
* {{cite book |url=http://www.nasa.gov/centers/dryden/pdf/87756main_H-524.pdf |title=Flight Experience With Shock Impingement and Interference Heating on the X-15-2 Research Airplane |publisher=NASA |first=Joe D. |last=Watts |date=October 1968 |id=NASA-TM-X-1669 |ref=harv}}
{{Refend}}

==External links==
{{Commons|Category:North American X-15}}
;NASA
*[http://history.nasa.gov/x15/cover.html NASA's X-15 website]
*[http://www.hq.nasa.gov/office/pao/History/hyperrev-x15/cover.html "Transiting from Air to Space: The North American X-15" (1998)]
*[http://www.hq.nasa.gov/office/pao/History/x15conf/cover.html "Proceedings of the X-15 First Flight 30th Anniversary Celebration, 8 June 1989"]
*[http://history.nasa.gov/monograph18.pdf ''Hypersonics Before the Shuttle: A Concise History of the X-15 Research Airplane'' (NASA SP-2000-4518, 2000)]
*[http://history.nasa.gov/ap11-35ann/interviewspdf/armstrong66.pdf Interview with Neil Armstrong about his experience in the X-15]
*[http://www.nasa.gov/centers/dryden/news/FactSheets/FS-052-DFRC.html NASA Armstrong Fact Sheet: X-15 Hypersonic Research Program]
*[http://www.dfrc.nasa.gov/Gallery/Photo/X-15/index.html X-15 photos at NASA Armstrong]
*[http://www.dfrc.nasa.gov/Gallery/Movie/X-15/index.html X-15 movies at NASA Armstrong]
*[http://www.nasa.gov/externalflash/x15_interactive/ Interactive X-15 portal by NASA] (uses Macromedia Flash)

;Non-NASA
*[http://www.sierrafoot.org/x-15/documents/X-15_design_proposal.pdf X-15 Advanced Research Airplane Design Summary (NA-55-221, 1955)]
*[http://historyinpieces.com/video/recovery-x15-supersonic-experimental-aircraft "Recovery of the X-15 Supersonic Experimental Aircraft"] at History in Pieces
*{{Internet Archive film clip|id=1959-06-11_X-15_Aloft|description="X-15 Aloft: First Free Flight Of Manned Space Plane" (1959)}}
*{{Internet Archive film clip|id=1962-07-19_X-15_Space_Record|description="X-15 Space Record: Plane Flown To 59-mile Mark" (1962)}}
*{{Internet Archive film clip|id=1960-08-15_space_triumph|description="Space Triumph: Discoverer Capsule Recovered From Orbit" (1960)}}
*{{Internet Archive film clip|id=1960-11-17_Nuclear_Navy|description="Nuclear Navy: First Polaris A-Sub Sails On Ocean Patrol" (1960)}}
*{{Internet Archive short film|id=gov.dod.dimoc.38379|name=History of the Air Force, 1954-1964: From Missile Development to Space (1977)}}
*[http://www.astronautix.com/craft/x15a.htm X-15] at Encyclopedia Astronautica
*{{IMDb title|55627|X-15}}

{{North American Aviation aircraft}}
{{X-planes}}
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{{Wikipedia|North American X-15}}
[[Category:North American Aviation aircraft|X-015]]
[[Category:United States experimental aircraft 1950–1959]]
[[Category:Rocket-powered aircraft]]
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[[Category:Hypersonic aircraft]]
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[[Category:Manned spacecraft]]
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[[Category:Suborbital spaceflight]]
[[Category:High-test peroxide]]
[[Category:1963 in spaceflight]]
[[Category:X-15 program|X-15 program]]