Despite its technical triumphs and support from aviators, the XB-70’s operational future unraveled almost as quickly as it took flight.
The North American XB-70 Valkyrie emerged from a United States Air Force requirement in the mid-1950s for a bomber capable of delivering nuclear payloads at speeds and altitudes beyond the reach of Soviet air defenses.
At the time, the primary strategic bomber in the U.S. arsenal, the Boeing B-52 Stratofortress, was subsonic—and thus increasingly vulnerable to advancing interceptor aircraft and surface-to-air missiles (SAMs). A faster—much faster—warbird was needed.
The XB-70’s Design
In 1957, North American Aviation won the contract to develop XB-70, a delta-winged behemoth designed to cruise at Mach 3 (over 2,300 miles per hour) and altitudes exceeding 70,000 feet, rendering it nearly untouchable by contemporary threats.
XB-70’s design was a marvel of engineering. Indeed, though the plane never entered service, it influenced the design and development of the legendary SR-71 Blackbird. The Valkyrie was powered by six General Electric YJ93 afterburning turbojet engines, producing a combined thrust of 180,000 pounds.
The Valkyrie’s sleek, aerodynamic shape featured a distinctive canard foreplane and a variable-geometry wingtip system: at supersonic speeds, the outer wing panels could fold downward up to 65 degrees, enhancing stability and harnessing compression lift—a phenomenon where shockwaves beneath the aircraft increase lift efficiency.
Constructed largely from stainless steel and titanium to withstand the intense heat of Mach 3 flight, the Valkyrie was painted white to reflect thermal radiation. Its cockpit, designed for a crew of four, included advanced avionics and ejection capsules for high-altitude emergencies. The XB-70 was, in essence, a technological leap into the future of aerospace.
Two XB-70 Prototypes Were Built
The first prototype, XB-70A-1, rolled out on May 11, 1864, in Palmdale, California, and made its maiden flight on September 21 of that year. A second prototype, XB-70A-2 followed in 1965. Together, these aircraft were intended to pave the way for a fleet of operational XB-70 bombers.
Valkyrie’s flight test program showcased its extraordinary capabilities while revealing the challenges of pushing aviation boundaries.
On October 14, 1965, the first prototype reached Mach 3.02 at 70,000 feet, proving its ability to achieve the speeds and altitudes envisioned by its designers. The second prototype later hit Mach 3.08, cementing the Valkyrie’s status as one of the fastest manned aircraft ever built. Its ability to cruise at such velocities over long distances—potentially up to 4,300 miles with aerial refueling—made it a theoretical game-changer for strategic bombing. Folding wingtips not only improved high-speed performance but also demonstrated the feasibility of adaptive aerodynamics, influencing later aircraft like the B-1 Lancer.
The XB-70’s use of exotic materials and its sophisticated cooling systems provided valuable data for future high-speed aircraft—including the SR-71. Pilots and engineers marveled at the XB-70’s sleek lines and raw power.
Yet there were flaws.
The Valkyrie Had Problems, Too
The first prototype suffered from hydraulic leaks, landing gear issues, and excessive skin temperatures during early flights, limiting its top speed until modifications were made.
Then, tragically, the second prototype collided with an F-104 Starfighter chase plane in 1966, killing two pilots and severely injuring the pilot at the controls of the XB-70. The second Valkyrie was destroyed in the crash, leaving only the first prototype to continue testing.
Despite its technical triumphs and support from aviators, the XB-70’s operational future unraveled almost as quickly as it took flight. Some of the factors behind the premature cancellation included the rise of missile technology. By the late 1950s, intercontinental ballistic missiles (ICBMs) like the Minuteman were emerging as the backbone of U.S. nuclear deterrence.
Faster, cheaper, and harder to intercept than manned bombers, ICBMs rendered the XB-70’s role obsolete before it could enter production. In 1961, the Kennedy administration slashed funding for the Valkyrie, reclassifying it as an experimental project rather than a deployable weapons.
Developed at the height of the Cold War, everything under development for the U.S. military had to be squared with advances in Soviet defenses. In the case of Soviet air defenses, the technological advances made by Moscow essentially rendered the XB-70 obsolete. Notably improved surface-to-air missiles (SAMs) and better interceptors, like the MiG-25, could potentially target the XB-70, forcing it to fly lower and slower—negating its primary advantages and exposing it to additional threats.
And the XB-70 was onerously expensive, with each production aircraft estimated at over $700 million in 1960s dollars (around $6 billion today!). Its reliance on rare materials and intricate manufacturing processes made mass production impractical, especially as the Air Force shifted resources to more versatile platforms like the B-52, and later, the B-1.
The Bomber That Might Have Been
The Cold War’s evolving nature favored flexible, multi-role aircraft over specialized bombers. The B-52, upgraded with stand-off missiles, and what was then the forthcoming FB-111 Aardvark offered cost-effective alternatives without the Valkyrie’s narrow mission profile.
So the XB-70 Valkyrie may be the most important warplane that never saw full-scale adoption. Its unique design and capabilities effectively inspired a generation of some of America’s most advanced planes that came immediately after the XB-70 was canceled.
About the Author: Brandon J. Weichert
Brandon J. Weichert, a Senior National Security Editor at The National Interest as well as a contributor at Popular Mechanics, who consults regularly with various government institutions and private organizations on geopolitical issues. Weichert’s writings have appeared in multiple publications, including the Washington Times, National Review, The American Spectator, MSN, the Asia Times, and countless others. His books include Winning Space: How America Remains a Superpower, Biohacked: China’s Race to Control Life, and The Shadow War: Iran’s Quest for Supremacy. His newest book, A Disaster of Our Own Making: How the West Lost Ukraine is available for purchase wherever books are sold. He can be followed via Twitter @WeTheBrandon.
Image: Wikimedia Commons.
