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Smart Bombs: Military, Defense and National Security

XB-70 Valkyrie: Mach 3 Bomber That Could Never Replace the B-52

XB-70. Image: Creative Commons.
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.

Key Points and Summary: The XB-70 Valkyrie, a supersonic bomber developed in the 1950s, promised to revolutionize aerial warfare with its Mach 3 speed and high-altitude flight.

-Designed to evade Soviet radar and deliver nuclear payloads, the Valkyrie was ultimately canceled in 1961.

-Factors contributing to its demise include budget constraints, the emergence of intercontinental ballistic missiles (ICBMs), and advancements in Soviet air defense systems that threatened its survivability.

-The changing strategic landscape, which emphasized the importance of a nuclear triad, also diminished the perceived need for such a specialized bomber, leading to the XB-70’s premature end.

-The continued high-level functionality of the B-52 bomber decades after its arrival might lead some to wonder why a replacement or additional nuclear-capable bomber may have been considered at a previous point in history.  

The XB-70 Was a Fail 

In the 1950s, North American Aviation engineered an ultra high-speed XB-70 Valkyrie bomber capable of hitting speeds greater than Mach 3, a development which suggests credible reasons why a supplement or replacement for the B-52 may have made sense. 

The prototype looked sleek, smooth, and fast and intended to introduce new levels of nuclear weapons attack possibility as the US surged further into the Cold War. 

The Valkyrie could cruise thousands of miles at 70,000 feet but was ultimately canceled in 1961. The speed of the aircraft was intended to ensure it could transit from one radar aperture or field of view to another while eluding enemy air defenses. 

The aircraft’s speed also meant it could avoid being followed or “tracked” by any interceptor aircraft

At the time, there were no Soviet aircraft capable of tracking the Valkyrie, so the concept seemed to make strategic and tactical sense. 

And yet, the XB-70 failed. Why? 

High-Speed Mach 3 1960s Bomber

It is interesting to see the long-term, historical emphasis placed on speed as a critical survivability tactic, as the ability to travel so quickly between radar fields of view is a key reason why modern hypersonic weapons are so challenging to track. 

The exact reasons why the prototype was canceled may be difficult to discern, yet published accounts refer to budget considerations to some extent. 

Perhaps it would have made great sense for the Air Force to operate a supersonic Mach 3 bomber to support or even replace the B-52 with an ability to penetrate enemy air defenses and conduct air attacks deep within enemy airspace.

Why Did the XB-70 Bomber Disappear? 

However, the rapid arrival of advanced Soviet Air defenses during these decades of the Cold War, modern versions of which are still regarded as among some of the best in the world, may have raised concerns about the continued survivability of the aircraft as well.  

XB-70 Valkyrie

XB-70 Valkyrie. Image Credit: Creative Commons.

Russian air defenses have a long history of growing effectiveness and have been upgraded for decades. They likely influenced the development of modern S-400 and S-500 systems, which are increasingly capable of tracking and targeting higher-speed aircraft, conducting node-to-node digital networking, and targeting aircraft at longer ranges on a more significant number of frequencies. 

Along with budget considerations and a changing threat landscape, there appear to have been other strategic factors as well. 

The arrival of ICBMs in the 1950s and 1960s led some decision-makers to think that nuclear-armed bombers might be redundant or less necessary. This view is mainly extinct these days at the Pentagon, given the near-universal belief in a critical need for a full air, ground, and undersea nuclear triad

Pentagon Need for Nuclear Triad

This kind of thinking seems quite significant, in retrospect, given today’s belief in a fully operational and ready nuclear “triad.” The conceptual framework of a nuclear triad rests on several things, including the risk of an enemy “bolt-out-of-the-blue” or massive, overwhelming attack. 

The arrival of ICBMs also meant the Soviets would also operate ICBMs. These weapons could potentially be launched “en masse” against the US to overwhelm US defenses with a massive attack or salvo of incoming missiles. 

For this reason, US thinkers crafting and refining a Strategic Deterrence Posture recognized that an air-dropped nuclear threat was still necessary to ensure potential adversaries were held at risk from the air and sea domains. 

XB-70

XB-70. Image Credit: Creative Commons.

If US ICBMs and land defenses were destroyed or overwhelmed, the US could ensure a massive retaliatory strike capability from undersea and the air. This strategic equation still exists today and proves vital to the Pentagon as it seeks to provide a potential adversary does not think a first-strike nuclear attack would be conceivable in any way. 

All of this meant one thing: the XB-70 bomber was toast. 

About the Author: Kris Osborn 

Kris Osborn is the Military Technology Editor of 19FortyFive and President of Warrior Maven – Center for Military Modernization. Osborn previously served at the Pentagon as a highly qualified expert in the Office of the Assistant Secretary of the Army—Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He has appeared as a guest military expert on Fox News, MSNBC, The Military Channel, and The History Channel. He also has a Masters Degree in Comparative Literature from Columbia University.

Written By

Kris Osborn is the Military Affairs Editor of 19 FortyFive and President of Warrior Maven - Center for Military Modernization. Osborn previously served at the Pentagon as a Highly Qualified Expert with the Office of the Assistant Secretary of the Army—Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He has appeared as a guest military expert on Fox News, MSNBC, The Military Channel, and The History Channel. He also has a Masters Degree in Comparative Literature from Columbia University.

2 Comments

2 Comments

  1. Mark powell

    January 28, 2025 at 11:56 am

    So what changed between the XB-70 being cancelled and the B-1 being commissioned?

  2. Bruce Rader

    January 29, 2025 at 9:28 pm

    That was, by far, the worst article I have ever encountered regarding the B-70.

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