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Mach 2 Milestone Anniversary
Flight was just nearing its 50th birthday when test pilot Scott Crossfield became the first to fly at twice the speed of sound.

Reaching Mach 2 in a Douglas Aircraft Co. D-558-II Skyrocket on Nov. 20, 1953 represented a very significant and necessary benchmark on the journey to manned space flight. However, initially it opened the door for the aeronautical advances required for regular encroachment of aircraft beyond the super high-speed realm of Mach 2.

D-558-2 launch from B-29 mothership
Photo left: A Douglas D-558-2 is launched from the B-29 mothership. NASA photo

Although the Skyrocket was designed for a top speed of about Mach 1.5, the addition of extensions on the four nozzles of its rocket engine enabled Crossfield to reach Mach 1.96 in shallow dives in previous flights.

"It was very close, but it was all the airplane had in it," Crossfield reflected. "Herman Ankenbruck, one of the engineers that was on the airplane, worked out analytically that we could go about Mach 2.01, with everything working perfectly and getting the advantage of cold weather. Everybody on the base knew that we were going to make the try, but very few people thought that we were going to make it - and frankly we had our own doubts that we just were asking the airplane to do more than it was ever designed to do," he added.

Scott Crossfield was a member of the elite test pilot cadre at the National Advisory Committee for Aeronautics (NACA) High-Speed Flight Research Station, now NASA's Dryden Flight Research Center in California's Mojave Desert. Before becoming the first man to reach Mach 2, he had flown the X-1, X-4, X-5, XF-92A and the D-558-I experimental aircraft.
Scott Crossfield in D-558-2 cockpit after first Mach 2 flight
Photo Right: Scott Crossfield, in the cockpit of a Douglas D-558-2, is welcomed back from the first Mach 2 flight. NASA photo

The three futuristic Skyrockets that arrived in the desert had fast written all over them, looking like rocket planes out of the old Buck Rogers comic series from the 1930s and 40s. In fact, 1950s TV super-hero Captain Midnight's Secret Squadron aircraft bore a strong resemblance to the Skyrocket.

The day of Crossfield's record breaking flight started out cold and blustery in stark contrast to the blistering heat that was generated by air friction on the Skyrocket at Mach 2.

The NACA flight test team chilled the liquid alcohol fuel, constricting it to allow more to be poured into the Skyrocket's fuel tanks, and laboriously waxed the rocket plane's skin to reduce aerodynamic drag. Early in the morning of Nov. 20, 1953, the Skyrocket was carried aloft by a U.S. Navy B-29 "mother ship," which climbed for more than 1 1/2 hours before reaching the launch altitude of 32,000 feet.

After dropping clear of the bomber, Crossfield ignited the aircraft's rocket engine and pointed the plane's nose skyward, reaching 72,000 feet before pushing over into a shallow dive. The Mach meter gradually crept upward as the fuel burned off, and the needle finally stopped at 2.005 - just a hair over twice the speed of sound before fuel was exhausted.

"Fortunately, I lucked out that day and managed to fly what Ankenbruck predicted, and came out right on the money, within half a percent," Crossfield said.

The rocket motor that propelled the Skyrocket was an LR8-RM-6, four-chamber Reaction Motors Co. engine that produced 6,000 pounds of thrust at sea level.

By Gray Creech, NASA Dryden Flight Research Center, Public Affairs