Quick LinksX-15-1 X-15-2 X-15-3 NB-52A NB-52B
The North American X-15 has many distinctions. It is the first aircraft that had a pressurized suit for pilots. It was the first aircraft to have flown to space, and as NASA describes it, the aircraft "provided a major technological stepping-stone to space."
✕ Remove Ads Photo: Smithsonian National Air and Space Museum l Flickr
The X-15 program had five aircraft in total. In this article, we will explore these technological marvels in detail.
1 X-15-1 Currently, at the National Air and Space Museum
Air Force serial
56-6670
Number of flights
81
According to John Anderson and Richard Passman, who authored the book 'X-15: The World's Fastest Rocket Plane and the Pilots Who Ushered in the Space Age":
"Three X-15s were built and were unofficially labeled by people in the program as Ship 1, Ship 2, and Ship 3...This harks back to the early twentieth century when sometimes airplanes were referred to by the name of ship'. "
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The X-15-1 was the first aircraft of the X-15 series. The highest speed recorded by the X-15-1 was Mach 6.06. Pilot Bob Rushworth achieved this on December 5, 1963.
Photo: NASA
The X-15-1 was later equipped with the higher-thrust XLR99 engine. Pete Peterson was the first pilot to take this aircraft with new engines and achieved a speed of Mach 4.11 and an altitude of 78,000 feet. According to the authors mentioned above, Pete and other pilots:
"contributed to the X-15 data collection by carrying out high-angle-of-attack stability tests and collecting aerodynamic, heat transfer, thermostructural stability and control, and performance data. "
✕ Remove Ads 2 X-15-2 The fastest X-15 flown
All in all, the X-15-2 had 53 flights. On November 9, 1962, NASA research pilot Jack McKay suffered injuries during the crash of the X-15-2. Despite the injury, he recovered and made 22 more flights as an X-15 pilot. Aviation Safety Network reported about the crash in the following way:
" Following the launch from the B-52 to begin flight 2-31-52, he started the X-15's rocket engine, only to discover that it produced just 30 percent of its maximum thrust. He had to make a high-speed emergency landing on Mud Lake, NV, without flaps but with a significant amount of fuel still in the aircraft. As the X-15 slid across the lakebed, the left skid collapsed; the aircraft turned sideways and flipped onto its back."
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After the crash, the aircraft was tested with a new thermal protection material. Modifications to the aircraft also meant that it had higher potential performance (thanks largely to the increased propellant capacity). The X-15-2 was later named X-15A-2 and reached a speed of Mach 6.72 (4,534 mph):
Number of flights as X-15-2
31
Number of flights as X-15A-2
22
The X-15A-2 is now exhibited at the Air Force Museum, Wright-Patterson Air Force Base, Ohio.
3 X-15-3 Piloted by Neil Armstrong on the first flight
Number of flights
65
Top speed
5.65
Wingspan
22 ft
Empty weight
14,000 lbs
Maximum altitude
354,200 feet
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The first flight of the X-15-3 took place on December 20, 1961, as the man who was to later immortalize space travel with the words "one small step for man, one giant step for mankind" - Neil Armstrong - piloted it. A few of the features of the x-15-3 include:
Advanced cockpit display panel Special adaptive control system Photo: NASA
The X-15-3 is the only aircraft of the X-15 to have met a fatal accident. On November 15, 1967, the pilot, Capt. Michael Adams was killed. After the aircraft took off from Delamar Lake, Nevada, the aircraft touched an altitude of 266,000 ft and reached a speed of Mach 5.2 before crashing, reported NASA:
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"Adams radioed that the X-15 "seems squirrelly," and then said "I'm in a spin." Through some combination of pilot technique and basic aerodynamic stability, Adams recovered from the spin, and entered an inverted Mach 4.7 dive. As the X-15 plummeted into the increasingly thicker atmosphere, the Honeywell adaptive flight control system caused the vehicle to begin oscillating. As the pitching motion increased, aerodynamic forces finally broke the aircraft into several major pieces."
4 NB-52A Nicknamed "The High and Mighty One"
The two aircraft we will now discuss are the non-standard Boeing B-52 Stratofortress. The B-52 Stratofortress, also known as "BUFF" [Big Ugly Fat Fellow], is an aircraft that has been used by the United States Air Force (USAF) since the 1950s. NASA later used the aircraft during the X-15 program. According to Pima Air and Base Museum:
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"Only three of the "A" model Stratofrtresses were built and all served solely as test aircraft for both Boeing and the Air Force. The oldest B-52 in existence... is the third "A" model built. This is one of two B-52s modified to carry the X-15 rocket plane."
According to air-and-space.com, "the B-52A, serial 52-0003, arrived at Plant 42 from Boeing on November 29, 1957, and was moved into the North American hangar for the beginning of modifications on February 4, 1958." Let's look at how many times the NB-52A was used to launch the aircraft we have previously discussed:
X-15-1
30
X-15-2
11
X-15-3
31
Photo: US Air Force | Wikimedia Commons ✕ Remove Ads
The aircraft was retired in October 1969 and is currently on display at the Pima Air and Base Museum.
5 NB-52B First flew on June 11, 1955
Before being assigned to support the X-15 program, the NB052 was a United States Air Force test aircraft. When the NB-52B first rolled out of Boeing's Seattle plant, it was dubbed RB-52B.
Heaviest load carried (after becoming a part of NASA)
53,100 lbs
Wingspan
185 feet
Top speed
390 knots
Maximum operating altitude
More than 50,000 feet
Photo: NASA
The NB-52B was nicknamed The Challenger and later dubbed Balls 8. According to NASA,
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"[it] participated in some of the most significant projects in aerospace history. At retirement, the air launch and research aircraft held the distinction of being NASA's oldest aircraft, as well as being the oldest B-52 on flying status. At the same time, it had the lowest number of flying hours (2443.8) of any B-52 in operation, having been used exclusively in the role it continued to perform so reliably for nearly 50 years."
The aircraft was formally retired on December 17, 2004. After a joint ceremony commemorating the retirement, the aircraft found a home at Edwards Air Force Base in California.
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