The XB-70 Valkyrie was 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 rivalry between the YF-12 and the XB-70.
North American Rockwell made the first Mach 3 bomber (Although the six-engine Valkyrie could only dash to Mach 3 due to aero heating and not cruising at that speed).
Their public relations firm was advertising every place they could about how their airplane could fly higher and faster than anyone could before.
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 took the seventh through ninth slots on the A-12 assembly line; these were designated as YF-12A high-altitude, Mach 3 interceptor.

The main changes involved modifying the A-12’s nose by cutting back the chines to accommodate the huge Hughes AN/ASG-18 fire-control radar initially developed for the XF-108 with two infrared search and track sensors embedded in the chine leading edge, and the addition of the second cockpit for a crew member to operate the fire control radar for the air-to-air missile system. This airframe could easily fly Mach 3.
As told by Donn A. Byrnes and Kenneth D. Hurley in their book Blackbird Rising: Birth of an Aviation Legend, they were both being tested at Edwards AFB at the same time, so naturally, they hung out at the same bar after work. One of the local watering holes was called Hernandez Hideaway.
YF-12 test pilots, often flew at Mach 3 more often than the XB-70 would do in a lifetime.
Jim Eastham had just about enough of the bragging he heard daily about the XB-70. Eastham was a Lockheed test pilot who had already flown the A-12 and was now flying the YF-12.

One evening at the bar Al White of the XB-70 program was raving about his high Mach numbers when Eastham couldn’t stand it any longer. 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 XB-70 was an extremely large airframe; the YF-12 was not small being 107 feet long. But if you compared the two, the Blackbird looked small.
Be sure to check out Linda Sheffield Miller, Col Richard (Butch) Sheffield’s daughter, Col. Sheffield was an SR-71 Reconnaissance Systems Officer) Facebook Page Habubrats for awesome Blackbird’s photos and stories.
Photo credit: U.S. Air Force and Peter Chilelli

Hmmmmn… Interceptor vs. Bomber. The XB-70 was all brute force and never came to fruition until the Rockwell B-1B, a much smaller airframe. The ultimate mission profile was under Mach, although we did have Mach 1.2 missions on the deck. The YF-12 idea was eventually scrapped cuz the missile technology at the time could not screen out the Launch Vehicle. The rest is history…. Before it’s retirement The Blackbird achieved the advertised Mach 3+… a lot.
Weren’t those big pieces just huge areas of the paint peeling off?