The only plane that could fly higher and faster than the SR-71 Blackbird was the X-15. North American Aviation, Inc created the plane.

One Fast Plane

According to NASA, the plane could blast through the air at 4,500 mph or higher, almost hitting Mach 6. It hit heights of 354,200 feet, which is over 67 miles.

The three X-15s flew 199 times, with the first flight piloted by Scott Crossfield on June 8. 1959. In total, 12 pilots flew for the program from all over North America and from multiple military branches.

There was one downside to this plane. It couldn't take off on its own. Instead, it needed to be carried into the air by the B-52 bomber. The two B-52s were the "High and Mighty One" and the "Balls 8." The bomber would drop the X-15 at 45,000 feet in the air at 500 mph.

X-15s Pilots

The plane's motors provided 70,400 pounds of thrust for about two minutes. The plane had some notable pilots. One of which was Neil Armstrong.

He flew the plane seven times but never made it into space. However, he achieved the 6th-fastest speed. Major Michael Adams was one pilot who made it to space. But on November 15, 1967, his X-15A crashed, and he was killed.

On his final flight, he broke the barrier between the sky and space that NASA and the Air Force used to determine entering space. It was a 50-mile barrier. Adam's last flight was his seventh in an X-15A, and he hit an altitude of 266,000 feet and reached a top speed of 3,617 mph.

The X-15 flew for ten years, and the flight data were used for the Mercury, Gemini, and Apollo space missions. Information from the X-15 flights also contributed to the Space Shuttle program.