Home » The Mach 3 rivalry between the YF-12 and the XB-70

The Mach 3 rivalry between the YF-12 and the XB-70

by Till Daisd
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The XB-70 Valkyrie had an extremely large airframe; the YF-12 was not small, being 107 feet long. But if you compared the two, the Blackbird looked small

The Mach 3 competition between the XB-70 and YF-12. Although the six-engine Valkyrie could only reach Mach 3 due to aero heating and was not able to cruise at that speed, North American Rockwell produced the first Mach 3 bomber.

Everywhere they could, their public relations company was pushing the idea that their aircraft could fly faster and higher than any other.

On the other side of Edwards Air Force Base (AFB), the YF-12 Blackbird kept its secrets near and dear. The YF-12 was a variant of the A-12 with a backseat for the missile launch controller.

The YF-12s, also known as YF-12A high-altitude Mach 3 interceptors, occupied the seventh through ninth slots on the A-12 assembly line.


The two primary modifications were the addition of a second cockpit for a crew member to operate the fire control radar for the air-to-air missile system and the modification of the A-12’s nose by cutting back the chines to accommodate the huge Hughes AN/ASG-18 fire-control radar, which was originally developed for the XF-108 and has two infrared search and track sensors embedded in the chine leading edge. This airframe could easily fly Mach 3.

Donn A. Byrnes and Kenneth D. Hurley tell in Blackbird Rising: Birth of an Aviation Legend that since they were both undergoing testing at Edwards AFB at the same time, they naturally spent their after-work together at the same bar. Hernandez Hideaway was the name of one of the local hangouts.

Test pilots of the YF-12 frequently accomplished more Mach 3 flights in a lifetime than the XB-70 would. Jim Eastham could take no more of the daily boasts about the XB-70. Eastham was a test pilot for Lockheed, having flown the A-12 and now the YF-12.

When Eastham couldn’t take it anymore, Al White from the XB-70 program was raving about his high Mach numbers one evening at the bar. He turned to White and said, “Al, we do more Mach 3 time in a single YF-12 mission than you guys have flown in your entire program.” Al looked at Jim, and without missing a beat, he said, “Yes, that’s true, Jim, but we lose pieces that are bigger than what you fly!

The YF-12, at 107 feet long, was not small, but the XB-70’s airframe was huge. However, the Blackbird appeared smaller in comparison to the other.

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Photo by U.S. Air Force and Peter Chilelli

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