The latest entry in the Library of Gimmick is The X-15 Rocket Plane: Flying the First Wings into Space by Michelle Evans. It is available on Amazon.com as well as Audible.
This is a biographical/educational account of the pilots, scientists, engineers, program managers, and even families that were part of the greatest “X-Plane project. The X-15 was the fastest manned rocket ship/plane ever designed and flown (until the Space Shuttle and Spaceship’s One and Two), capable of both atmospheric and sub-orbital flights between 50 to 62 miles in altitude.
Amazon.com provides the following portions (edited) of the book’s description. With the Soviet Union’s launch of the first Sputnik satellite in 1957, the Cold War soared to new heights as Americans feared to lose the race into space. The X-15 Rocket Plane covers an unsung, little-known story of the X-15’s rise to meet this purpose and expanded human-controlled spaceflight efforts.
The book itself can be explained by the back story. The X-15 rocket research airplane was built by the Los Angeles Division of North American Aviation for the U.S. Air Force, the U.S. Navy, and the National Aeronautics and Space Administration NASA).
The craft was designed to conduct research experiments during actual flight conditions beyond the Earth’s atmosphere which included the following:
- Bring manned aerial and space flight together, both in Earth’s atmosphere and in low, outer space. It became the first winged aircraft to attain velocities of Mach 4, 5, and 6 which was double the speed of the famed Lockheed SR-71 Blackbird.
- Achieve a flight speed of Mach 6 (or six times faster the speed of sound). It was considered a hypersonic craft, meaning it flies far greater than the speed of sound, the aircraft is said to be hypersonic. Typical hypersonic speeds are greater than 3000 mph and a Mach number greater than five.
- Reach an altitude of 250,000 feet, which is roughly 50 miles in altitude (where no atmosphere to support wings and standard control surfaces exist). In the US, the recognized boundary of “space” begins at 80.4km (50 miles), or 264,000 feet. The internationally-recognized limit of space is called the Karman Line which is set at 100km (62 miles, or 380,000 feet). As a reference, “Low Earth Orbit” (LEO) is between 160km (100 miles, 525,000 feet) to 2,000km (1,240 miles, 6.5 million feet).
- Finally, it was used to evaluate the handling of thermodynamic loads from heat generated at its tremendous speed, making an adjustable liquid-fueled rocket, safely reentry into Earth’s atmosphere, and making a safe landing.
There were three X-15 aircraft built, and they were flown by 12 test pilots which included the following (and the number of flights):
Scott Crossfield, North American Aviation, 14
Joseph A. Walker, NASA, 25
Robert M. White, USAF, 16
Forrest S. Petersen, USN, 5
John B. McKay, NASA, 29
Robert A. Rushworth, USAF, 34
Neil A. Armstrong, NASA, 7
Joe H. Engle, USAF, 16
Milton O. Thompson, NASA, 14
William J. Knight, USAF, 16
William H. Dana, NASA, 16
Michael J. Adams, USAF, 7
Neil Armstrong, of course, was famous for his later NASA flights on both Project Gemini and Apollo (when he became the first human to walk on the Moon).
Joe Engle became a NASA Space Shuttle mission commander, starting with the second flight of Shuttle Columbia. He also wrote the forward for The X-15 Rocket Plane.
NASA’s Dryden Research Center was the headquarters and center of the X-15 program that included flight preparation and testing. Dryden was based on the grounds of Edwards Air Force Base in the Mojave Desert. It is now called NASA Armstrong Flight Research Center (or AFRC) in honor of Neil Armstrong and his contributions to the X-15, NASA’s Gemini and Apollo programs, and being the first man to set foot on the Moon.
The X-15 was launched from the wing of a B-52 Stratofortress around 40 to 45,000 feet, due to the large quantities of fuel required for achieving its incredible speeds and altitude.
With thinner air, the X-15 was past the point of a conventional rocket’s Max-Q, or maximum aerodynamic loading in the lower/denser part of the atmosphere versus ascent speed.
Of all the flights, most were successful except for two when John McKay flipped over in X-15 No. 2 and suffered traumatic back injuries as a result. Michael J. Adams was the only pilot to die in an X-15 accident when he suffered spatial disorientation in the No. 3 craft and crashed.
Various feats and records were set with the X-15.
On June 8, 1959, the first one labeled X-15A-1 was released from a NASA NB-52B flying at 37,550 feet (11,445 meters), marking the first flight of the X-15 rocket plane with North American Aviation test pilot and engineer Scott Crossfield in the cockpit.
With the concurrent Mercury manned spaceflight program, the United States was on a fast track into space but lacked critical data needed to confirm this. The X-15 program helped to gain knowledge of aerodynamic heating, reentry conditions, acceleration and deceleration forces, and reactions of man to weightlessness.
On Sept. 17, 1959, the first powered flight took place on X-15A-1. Crossfield easily reached Mach 2.1 and an altitude of 52,341 feet (15,954 meters).
Next for the X-15 was a more powerful rocket motor. Capable of burning 18,000 pounds (8,165 kilograms) of liquid oxygen and anhydrous ammonia in a mere 85 seconds.
The X-15’s single XLR99 engine was installed for flight on X-15A-1, flight No. 34, which on Nov. 15, 1960, took U.S. Air Force test pilot Robert White to Mach 4.4 and 77,450 feet (23,607 meters).
A new version of the craft (known as the X-15A-2) was designed for MACH 8 flight, at a 100,000 ft altitude (30,480 meters) and creating potential temperatures of more than 2,400 degrees Fahrenheit (1316 degrees Celsius).
This was accomplished through design changes which included two external jettisonable fuel tanks, longer main gear, lengthened and lowered nose gear, the fuselage extended 29 inches, improved windshield design, ablative material on the outer skin, a removable right-hand wingtip to accept test materials, removable lower vertical fin to permit installation of ramjet engines and accommodations for photographic experiments.
NASA pilot Joe Walker reached a record altitude of 354,200 feet (67 miles, or 108 kilometers) on Aug. 22, 1963 — a mission in which the X-15 exceeded design specifications and earned Walker astronaut wings (the first of the 8 X-15 pilots to do so).
Air Force Capt. William “Pete” Knight took X-15A-2 to the fastest speed recorded during the program, Mach 6.7, during an Oct. 3, 1967 flight that reached an altitude of 102,100 feet (31,120 meters). Knight had traveled twice as fast as a bullet, and this speed stood until Space Shuttle Columbia reentered the atmosphere at Mach 22 in April 1981.
The X-15 ultimately provided the Space Shuttle design team with invaluable information on hypersonic flight, in particular, how to reenter the earth’s atmosphere with a winged vehicle and how to precisely land a low L/D (lift-to-drag) unpowered vehicle.
Later, two more X-15 pilots became NASA astronauts — Neil Armstrong (not pictured) on the Gemini and Apollo programs, and Joe Engle (pictured here on the left), who commanded the space shuttle Columbia on its second flight (STS-2) in November 1981 and Discovery in September 1985 (STS-51I).
The final flight of the X-15 was in December of 1967 with Bill Dana at the controls. It was the 199th flight of the legendary craft. There was planned a 200th (final) flight, but due to technical glitches this never materialized and the program was soon concluded.
The X-15, however, had achieved the status and fame as the most successful research aircraft in U.S. history. It produced a wealth of scientific data and aeronautical feats that remain unparalleled. It produced roughly 760 technical reports, awards, and honors for the X-15 team, and pioneered many advances in aerospace technology which included improved materials, hypersonic aerodynamics, astronomy, and spaceflight.
The X-15 Rocket Plane celebrates the science and engineering that went into this legendary program, which not only led to the Space Shuttle program but forwarding commercial/manned space efforts such as Burt Rutan’s SpaceShip One (of Virgin Galactic fame), Blue Origin, SpaceX, and others.
And it finally gives credit to the Astronaut rating that many of the X-15 pilots who were long overshadowed by the Mercury, Gemini, and Apollo rocket programs. By the time of the Apollo 11 moon landing, thirty-one American astronauts had flown into space—eight of them astronaut-pilots of the X-15. The X-15 Rocket Plane gives them the due credit that they deserved alongside the engineers, scientists, managers, military, and others who often worked below and/or above their ranking and station to help this program succeed.
Once again, I find a book that does a stellar job of inspiring students and rising professionals in STEM, aerospace, and spaceflight. I give The X-15 Rocket Plane a solid 5 out of 5 stars, and I would consider this essential reading to inspire and educate those involved with the pursuit of space program initiatives.
As before, you can purchase this book at Amazon.com or get an audio version on Audible. 
For The Great Galactic Space Gimmick, I’m Gimmick Commander Ben Faltinowski. 📚 📖 🔭 🚀 🧪 🧮 💫
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