‘When the Valkyrie flies at Mach 3 it loses pieces that are bigger than the Blackbird, but the XB-70 flies less Mach 3 time than the YF-12.’ The Mach 3 rivalry between the YF-12 and XB-70.

‘When the Valkyrie flies at Mach 3 it loses pieces that are bigger than the Blackbird, but the XB-70 flies less Mach 3 time than the YF-12.’ The Mach 3 rivalry between the YF-12 and XB-70.

By Linda Sheffield Miller
Oct 8 2023
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XB-70 Valkyrie Mach 3 bomber

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

The futuristic XB-70A was originally conceived in the 1950s as a high-altitude, nuclear strike bomber that could fly at Mach 3 (three times the speed of sound) — any potential enemy would have been unable to defend against such a bomber.

SR-71 T-Shirts
CLICK HERE to see The Aviation Geek Club contributor Linda Sheffield’s T-shirt designs! Linda has a personal relationship with the SR-71 because her father Butch Sheffield flew the Blackbird from test flight in 1965 until 1973. Butch’s Granddaughter’s Lisa Burroughs and Susan Miller are graphic designers. They designed most of the merchandise that is for sale on Threadless. A percentage of the profits go to Flight Test Museum at Edwards Air Force Base. This nonprofit charity is personal to the Sheffield family because they are raising money to house SR-71, #955. This was the first Blackbird that Butch Sheffield flew on Oct. 4, 1965.

As impressive a technological feat as the B-70 represented, the aircraft was under development at a time when the future of the manned bomber was uncertain. During the late 1950s and early 1960s, many believed that manned aircraft were obsolete, and the future belonged to missiles. As a result, the Kennedy Administration ended plans to deploy the B-70. Two experimental XB-70A prototypes were under construction at North American Aviation when the program was canceled. Even so, the USAF bought the two Valkyries to test aerodynamics, propulsion and other characteristics of large supersonic aircraft.

Nevertheless, North American Aviation had built 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) and their public relations firm was advertising every place they could about how their airplane could fly higher and faster than anyone could before.

‘When the Valkyrie flies at Mach 3 it loses pieces that are bigger than the Blackbird, but the XB-70 flies less Mach 3 time than the YF-12.’ The Mach 3 rivalry between the YF-12 and XB-70.

The YF-12 Blackbird

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.

Mach 3 rivalry

YF-12 test pilots, often flew at Mach 3 more often than the XB-70 would do in a lifetime.

SR-71 print
This print is available in multiple sizes from AircraftProfilePrints.com – CLICK HERE TO GET YOURS. SR-71A Blackbird 61-7972 “Skunkworks”

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) Twitter Page Habubrats SR-71 and Facebook Page Born into the Wilde Blue Yonder for awesome Blackbird’s photos and stories.

Photo credit: U.S. Air Force and Peter Chilelli

Lockheed SR-71 Blackbird model
This model is available in multiple sizes from AirModels – CLICK HERE TO GET YOURS.

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Linda Sheffield Miller

Linda Sheffield Miller

Grew up at Beale Air Force Base, California. I am a Habubrat. Graduated from North Dakota State University. Former Public School Substitute Teacher, (all subjects all grades). Member of the DAR (Daughters of the Revolutionary War). I am interested in History, especially the history of SR-71. Married, Mother of three wonderful daughters and four extremely handsome grandsons. I live near Washington, DC.

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