Supersonic Flight

On Tuesday, October 14, 1947, a B-29 bomber took off in the Mojave Desert in California. Instead of a bomb, it carried another plane.

Chuck Yeager & the X-1

The Bell X-1 “research vehicle” was a rocket fired aircraft. As the bomber climbed, test pilot Capt. Charles E. “Chuck” Yeager, climbed into the rocket aircraft. At 20,000 feet (6100 meters) the bomber released the new aircraft and Yeager.

Yeager fired the rocket and his small aircraft experienced 6000 pounds of thrust, quickly climbing. At Mach .85, Yeager temporarily stopped accelerating because the aircraft was untested at that speed. No wind tunnel could stream air that fast. He resumed acceleration and, at 40,000 feet, the aircraft passed the speed of sound.

Yeager brought the aircraft to Mach 1.06, a speed faster than any person or machine ever traveled before. Engineers were unsure of what might happen. Some predicted a loss of control or even a disintegration of the aircraft, but it flew straight and steady. Soon enough, Yeager slowed down and landed. That flight heralded the start of the supersonic era.

Engineering Matters

Supersonic flight wasn’t simply a matter of flying continually faster. Fluid dynamics function differently at speeds above the speed of sound. Isaac Newton first published a good guess about the speed of sound by measuring the difference between a flash of light from a cannon at a set distance and the resulting sound. Future scientists continued refining both the speed of sound and also how various properties acted above and below the speed of sound.

The scientists concern was two-fold. First, because air flows over a wing at slightly higher speed than under it, they worried these differences could tear a wing apart as an aircraft approached supersonic speeds. Secondly, crossing the speed of sound creates an extremely thin but strong shock wave that could also damage the aircraft.

Their easiest task was creating a rocket pushing an aircraft beyond the speed of sound. A more difficult task involved keeping the aircraft intact and under control of a pilot.

John Stack & NACA

Researcher John Stack did much of the research into shock waves and supersonic flight during the 1930s. The National Advisory Committee for Aeronautics (NACA, later renamed NASA) sponsored the research. However, the agency initially declined to fund for a supersonic airplane.

During WWII, NACA remained underwhelmed at the thought of diverting resources for a supersonic aircraft. However, by 1943 they greenlighted limited research to “design features of a transonic airplane could not hurt anyone, providing they did not distract from more pressing business.”

Shortening an extremely long story, Stack worked with Kotcher to build the X-1.