Book excerpt: Designed without horizontal stabilizers, the X-4 Bantam had a semi-tailless design that bore some resemblance to Germany¿s Me-163 rocket plane. The small, twin-jet craft relied on combined elevator and aileron surfaces ¿ known as elevons ¿ for pitch and roll control. The role of the X-4 was to explore the transonic speed zone, and to determine whether the design would lessen the stability and control problems affiliated with compressibility. Although two Bantams were built, only one proved mechanically sound. The second was flown over eighty times by Northrop, Air Force and NACA pilots. They learned that the X-4 was sensitive in pitch, and showed a tendency to ¿hunt¿ about all three axes as it approached Mach 1.0. Thus, the X-4¿s design proved a failure. Originally printed by Northrop, NACA and the USAF, this handbook provides a fascinating glimpse inside the cockpit of this experimental plane. The manual was recently declassified and is here reprinted in book form.