The Bell X-1 earned its place in history. On October 14, 1947 the aircraft—which was piloted by U.S. Air Force Captain Charles E. "Chuck" Yeager—was the first to reach the speed of 1,127 kilometers or 700 miles per hour, Mach 1.06, at an altitude of 43,000 feet.

The orange-painted aircraft, named "Glamorous Glennis" as a tribute to Yeager's wife, was air-launched at an altitude of 23,000 feet from the bomb bay of a Boeing B-29. The X-1 then used its rocket engine to climb to its test altitude. It was the first of 78 flights including the March 26, 1948 flight with Yeager at the control that attained a speed of 957 miles per hour, Mach 1.45, at an altitude of 71,900 feet—the highest velocity and altitude reached by a manned aircraft to that point.

Originally designated the XS-1, the Bell X-1 was developed as part of a cooperative program that was initiated at the tail end of the Second World War by the National Advisory Committee for Aeronautics (NACA) and the U.S. Army Air Forces to develop a special manned transonic and supersonic research aircraft.

The program continued with the X-1B, which was similar in design to the X-1A but it featured a slightly different wing configuration. The X-1B's flight research was primarily related to aerodynamic heating along with the use of small "reaction" rockets for directional control. This upgraded version of the X-1 made its first powered flight in October 1954, and soon after the U.S. Air Force transferred the X-1B to NACA, which was the predecessor to NASA. Under the guidance of NACA the X-1B was used in numerous heat and control tests, and these proved crucial in developing the control systems for the later X-15.

On its test missions the X-1B was carried under a "mother" aircraft and released between 25,000 and 35,000 feet; and after release the rocket engine was fired under full throttle for less than five minutes. After all of the alcohol-water fuel mixture and liquid oxygen were consumed the pilot would glide the aircraft back to the ground for landing! NACA continued its tests until January 1958, when cracks in the fuel tanks forced its grounding.

The X-1B was used in a total of twenty-seven flights, and the sole test aircraft is now at the National Museum of the United States Air Force, Wright-Patterson Air Force Base in Dayton, Ohio.

While the X-1 program continued, the projected X-1C, which was intended to test armaments and munitions in the high transonic and supersonic flight regimes, was canceled while still in the mock-up stage. The development of the supersonic-capable aircraft including the North American F-86 Sabre and North American F-100 Super Sabre were able to accomplish what the X-1C was meant to test, and that eliminated the need for the aircraft.

The subsequent X-1D was designed to be the first of the second generation of supersonic aircraft, and it was to follow the X-1B in conducting heat transfer research. It was damaged in its first and only successful flight, and after being repaired the prototype was lost in a fuel explosion during preparations for its first powered flight. It was jettisoned from its EB-50A mothership and decoyed upon impact.

The last of the series was the X-1E, and it was the second of the original X-1s to be fitted with new wings, turbo-driven fuel pumps and a knife-edge windscreen. The modified X-1E was flown by NACA from December 1955 until November 1958.

The research techniques utilized by the X-1 program were to set the pattern for all subsequent X-craft projects, while the flight data collected by NACA proved invaluable in U.S. fighter designs programs throughout the latter half of the twentieth century.

Peter Suciu is a Michigan-based writer who has contributed to more than four dozen magazines, newspapers and websites. He is the author of several books on military headgear including A Gallery of Military Headdress, which is available on Amazon.com.