X-1 was designed to explore that space - and ultimately fly beyond it, becoming a supersonic craft.

Transonic aircraft reach speeds very near the speed of sound, greater than 250 mph but less than 760 with about a Mach 1. Army Air Force and the National Advisory Committee for Aeronautics (NACA) knew you could theoretically design objects to fly at supersonic speeds: German V-2 ballistic missiles were known to fly at the speed of sound.īut American aerospace engineers had a big and important gap in their data on “transonic” flight - that region between Mach 0.8 and Mach 1.2 - van der Linden says. (The speed at which sound travels is the sound barrier when an aircraft exceeds this speed and experiences increased drag, that’s breaking the sound barrier.) There was something about getting close to the speed of sound - which varies with air density but is around 761 miles per hour at sea level - that was causing big problems. “He thought maybe it wasn’t possible to go supersonic.” But when reaching higher speeds in prolonged dives, pilots would encounter something termed “compressibility” - shockwaves built up in front of the aircraft, eventually freezing the control surfaces. World War II fighter aircraft with piston engines had become about as powerful as such engines could allow, routinely edging up to, if not quite reaching, 500 miles per hour in level flight. This included finding ways to make aircraft fly faster, according to van der Linden. Military sought any advantage it could in an effort to surpass the military capabilities of the Soviet Union. When World War II ended and the Cold War began, the U.S. “It sailed right through the alleged barrier.” The purpose of Bell X-1 “The X-1 apparently flew beautifully,” van der Linden says. He took the X-1 right up to the sound barrier and flew straight on through. “They knew it was stable, because a high-powered bullet is accurate, which means we can fly straight,” he says.Īfter 50 test flights - and some key modifications - that’s exactly what Air Force Pilot Chuck Yeager did on October 14, 1947. He is the National Air and Space Museum Curator of Special Purpose Aircraft. 50 caliber bullet, and that became the fuselage shape of the X-1,” Bob van der Linden tells Inverse. “They took the bullet shape of an M-2 Browning machine gun bullet, a. It would be called the X-1 and the company’s engineers took their inspiration from a known success. Air Force) and the National Advisory Committee for Aeronautics (the forerunner of NASA) asked Bell Aviation to build an experimental aircraft to explore the aerodynamics of flight near the speed of sound. Army Air Force (the forerunner of the U.S. High-powered bullets did it all the time.īut whether or not you could do it in an airplane - well, that was a whole different question. The thing about the sound barrier in the 1940s was that everyone in aviation knew that it was theoretically possible to travel faster than sound.

Sound barrier speed