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Review: The X-15 Rocket Plane

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The X-15 Rocket Plane: Flying the First Wings into Space
By Michelle Evans
University of Nebraska Press, 2013
Hardcover, 450 pages, illus.
ISBN 978-0-8032-2840-0
US $36.95

In the early 1980s, I remember watching a fascinating documentary, The Rocket Pilots. It covered the history of the X-1, X-2, and, most of all, the X-15. Perhaps the most interesting parts of the documentary were the interviews with Chuck Yeager, Scott Crossfield, and others who described their pioneering work at the dawn of the space age. The X-15 was literally a cutting-edge spacecraft, and the scientific and engineering knowledge gleaned from its development provided the groundwork of other NASA vehicles, in particular the Space Shuttle. It was NASA’s premier hypersonic research craft and the agency’s name was prominently displayed on the X-15’s vertical stabilizer.

There have been numerous histories of the X-15 program published over the decades, and the latest is The X-15 Rocket Plane. What makes this book particularly interesting and different from previous titles is the emphasis on the men and women of the X-15 program as opposed to the engineering development of the X-15, although that is interwoven in the book’s narrative. This book is the story not only of the test pilots, but the engineers, technicians, and managers at North American Aviation, which was the prime contractor for the X-15, and at NASA responsible for the direction and success of the program.

This book is the story not only of the test pilots, but the engineers, technicians, and managers at North American Aviation and NASA responsible for the direction and success of the program.

Michelle Evans knew it was imperative to interview as many of the surviving pilots of the hypersonic craft (and sometimes the wives of those pilots) as possible. She started her preliminary interviews in the early 1980s, had to shelve the project for two decades, but then resumed research in earnest for this book in 2004. She recounts her months-long effort to arrange an interview with Neil Armstrong before finally pulling up in front of his modest home in Ohio and having the opportunity to listen to him speak of his time on the program before joining the astronaut corps.

She also interviewed X-15 pilots Joe Engle (who wrote the book’s foreword), Forrest Peterson (the only Navy pilot of the X-15 program), and Scott Crossfield (who died in 2006). Of those who worked on the program, she interviewed Walt Williams (who died in 1995 and gives you some idea how many years Evans had devoted to the book), who worked on a number of the X programs, starting with the X-1, and as many of the surviving engineers and technicians she could locate. Interview transcripts from interviews with other former pilots and managers, like Dr. Harrison “Stormy” Storms who was vice president at North American Aviation and the company’s chief engineer on the X-15, were also prime sources of information.

There were a number of aerospace firms that became involved in the assault on the sound barrier and hypersonic flight. These companies included Bell Aircraft (X-1 and X-2), Douglas Aircraft (with the Skyrocket and X-3 Stiletto), and North American Aviation (NAA) with the X-15. These research aircraft involved first the NACA and later NASA. The propulsion sub-contractor for the X-15 was Reaction Motors, and Evans recalls the difficulties of designing and building this rocket engine that could be throttled, and the challenge of making it reliable.

Scott Crossfield left the NACA in 1955, Evans relates, to go to work at NAA; he became the chief test pilot for the company on the X-15. Crossfield became, perhaps, the X-15’s most famous test pilot, but there were numerous others recruited by NASA to pilot the sleek black rocket plane.

Evans chose to devote a chapter to key individuals in the X-15 program, with the first chapter on Scott Crossfield. Chapter 2 is spent covering the career of pilot Joseph A. Walker and his accomplishments with the X-15. The missions by pilot Robert M. White are covered in Chapter 3, including his record altitude flight of 314,750 feet—over 95 kilometers above the surface of the Earth—on July 17, 1962. The career and flights of Forrest Peterson are recorded in Chapter 4. John “Jack” McKay’s missions are covered in Chapter 5, and Evans interweaves the pilot’s remarks on specific aspects of each flight, as she did in the other chapters. One of McKay’s flights resulted in the X-15 rolling over during landing in 1962 and another time running off the lakebed after landing in May 1966, and Evans explains their causes.

Robert Rushworth’s flights in the X-15 are related in Chapter 6; Rushworth broke the Mach 6 barrier in November 1961. In this chapter, Evans states that of all the interviews with the X-15 pilots she conducted for the book, no pilot was more highly regarded than Rushworth, yet his abilities are often overshadowed by those of Neil Armstrong and Scott Crossfield, perhaps for obvious reasons. Armstrong is the subject of Chapter 7. Evans succeeds in putting on the page the personality and character traits of each pilot, and she does a good job of it with Armstrong as well.

X-15 pilot Joe Engle, was the subject of Chapter 8. Engle later entered the Apollo program and was part of the backup crew for Apollo 14, and was selected as Lunar Module Pilot for Apollo 17, but was pulled from the crew lineup and replaced by Dr. Harrison Schmitt.

In Chapter 9, “Iconel Meets Celluloid,” the author discusses the less than successful portrayal of the X-15 program in the appropriately titled film, X-15, which starred Charles Bronson. Evans used that time period—the movie was released in 1961—to discuss other aspects of the program before and after the film’s debut.

Evans writes, “In the more than fifty years that have passed since the beginning of the X-15, we rarely have a jet surpass 1,000 miles per hour. It is a sad testament to our lack of courage, our aversion to risk, our skittishness of pursuing the unknown in the way these people once did.”

Pete Knight’s record-setting and nearly disastrous flight in October 1967 is recalled with appropriate drama in Chapter 10. Knight achieved Mach 6.7 in his X-15A-2, but the vehicle suffered burn through in its skin when its white ablative coating failed. Knight was unable to drop the depleted external tanks and there was severe damage to the rear portions of the X-15. If Knight had pushed the X-15 to Mach 7 and flown longer, there would have been structural failure and both Knight and the X-15 would have been lost.

In Chapter 11, “Chasing Experiments,” Evans describes the career of X-15 pilot William Dana, whom Evans also was able to interview. This chapter also described some of the experiments that were deployed on Dana’s flights. In Chapter 12, Evans writes about the career of Michael Adams, and relates Adams’ last X-15 mission when the craft went into a spin and the craft airframe began to fail. All telemetry was lost between 80,000 and 70,000 feet (24,400 and 21,300 meters) and X-15 No. 3 broke apart before reaching 60,000 feet (18,300 meters). Adams died on November 15, 1967, the only pilot to perish during the X-15 program. The last chapter of the book describes the work of Harrison A. Storms on the X-15 as chief engineer on the project at North American Aviation.

The book is illustrated with several photographs in each chapter. This is by no means a photo book, and it is not intended to be. What is surprising about this book is that there are no citations whatsoever, a most curious decision coming from a university press title. Evans provides a list of sources at the end of the book, including the dates of the interviews, and printed matter consulted. However, there is no question her research was thorough and is careful to note when she herself conducted the interview, as opposed to quotes taken from transcribed interviews conducted by others. There are no appendices, which would have been helpful with respect to the X-15 missions.

The X-15 program pushed the envelope of propulsion, materials, hypersonic research, and achievement in many other areas the likes of which we do not read about today. In the closing chapter of the book, Evans wrote, “In the more than fifty years that have passed since the beginning of the X-15, we rarely have a jet surpass 1,000 miles per hour. It is a sad testament to our lack of courage, our aversion to risk, our skittishness of pursuing the unknown in the way these people once did.”

Evans’s chronicle of the X-15 program and the skilled pilots, brilliant engineers, and capable mangers of that program adds a significant compilation to the body of knowledge we have of it, and especially the personal recollections of the X-15’s pilots, most of whom have passed away. It is the mark of a good historian to ask the right questions of those who were there, and record the answers for future generations to read and absorb. The X-15 Rocket Plane is an engaging account of America’s push into space before pilots became astronauts, and America began a new era of exploration beyond the Earth to the Moon.