Here's What You Need to Remember: The plane claims a speed record of 2,070.101 mph and an altitude record of 80,257.65 feet, both of which were surpassed by the SR-71.

Before the famous SR-71, there was the YF-12, which emerged from Lockheed Martin in the 1960s. It had a short life and was never actually used operationally by the military, but it did form the basis for the SR-71, which had a much longer life.

Only three of the planes were built. Two of the YF-12s were flown as part of a joint Air Force-NASA research program throughout the 1970s, while a third one was lost in a fire in 1971, according to NASA’s website.

The jet was developed under  Clarence "Kelly" Johnson, Lockheed Martin's vice president for Advanced Development Projects, as part of the company’s famous Skunkworks.

“The project didn't begin entirely from scratch, however,” we wrote of the plane earlier this year. “In actuality, the YF-12 was the twin-seat version of the top-secret single-seat Lockheed Martin A-12, and its design became the forerunner of the highly sophisticated SR-71 Blackbird strategic reconnaissance aircraft. Unlike the unarmed Blackbird, which used speed in its defense, the YF-12 was armed with three air-to-air missiles.

“The YF-12 allowed NASA researchers at all four of the agency's aeronautical centers (Langley, Lewis [now Glenn], and Ames as well as the Flight Research Center) to study the thermal, structural, and aerodynamic effects of sustained, high-altitude, Mach 3 flight,” the site said.

“Painted flat black, the YF-12 was fabricated primarily from titanium alloy, which enabled it to withstand skin temperatures of over 500º F.

During its nine years of existence, the YF-12 had slightly less than 300 flights, of a total of about 450 flight hours. And it was thought to be one of the fastest jets ever to fly. The plane claims a speed record of 2,070.101 mph and an altitude record of 80,257.65 feet, both of which were surpassed by the SR-71 later.

“NASA and the Air Force announced joint involvement in a YF-12 research program. The agendas differed, with the Air Force focusing on combat research and NASA engineers initially focusing on a study of flight loads and structural heating,” NASA said on its website. “Much of the NASA research was concerned with the viability and development of supersonic cruise aircraft. Two YF-12As (tail numbers 935 and 936) were removed from Air Force storage for the program. On December 11, 1969, 935 successfully made its first flight as a NASA-USAF research plane and inaugurated the program. On June 24, 1971, 936 experienced the fuel line failure described above.”

The only surviving YF-12 is housed at the U.S. Air Force Museum at Wright-Patterson Air Force Base.

Stephen Silver, a technology writer for The National Interest, is a journalist, essayist, and film critic, who is also a contributor to The Philadelphia Inquirer, Philly Voice, Philadelphia Weekly, the Jewish Telegraphic Agency, Living Life Fearless, Backstage magazine, Broad Street Review and Splice Today. The co-founder of the Philadelphia Film Critics Circle, Stephen lives in suburban Philadelphia with his wife and two sons. Follow him on Twitter at @StephenSilver.

This article was published earlier and is being reposted due to reader interest. 

Image: NASA.