The North American X-15 was the last in a line of manned rocket-powered research airplanes built during the 1950s to explore ever-faster and higher flight regimes. This was an era before computers were commonplace, and the only way to investigate the unknown was to go there. The program was launched in 1954 specifically to produce the first hypersonic (velocities greater than five times the speed of sound) manned aircraft. Forward-thinking researchers also decided to design the airplane to fly to the edge of space, long before the manned space program had begun in earnest.
An in-depth history of the X-15 program may be found in "Hypersonic: The Story of the North American X-15" by Dennis R. Jenkins and Tony R. Landis. This book is a collection of illustrations that were assembled for "Hypersonic" but would not fit into the finished work. Since many of these are significant and most have never before been published, it was decided to print this scrapbook as a companion volume to "Hypersonic." With more than 350 b&w and 50 color photos, this scrapbook provides an excellent visual look at a very exciting research program.