Meet the XB-70 Valkyrie, Almost the World’s First Nuclear Aircraft


The Valkyrie was a plane decades ahead of its time, pushing the aeronautical engineering of the early 1960s well beyond what had been thought possible. It was even slated to become the world’s first nuclear-powered bomber.
The massive B-52 was the U.S.’s long-range strategic bomber in the 1950s, used to extend the range of nuclear weapons worldwide. The Pentagon sought an eventual replacement, a bomber that could cruise at ultra-high altitude, carry nuclear bombs, and stay aloft for extended periods.
It also needed extreme speed to escape intercepting fighters, the primary threat to long-range bombers at the time. Since no one thought ordinary jet engines could produce enough power efficiently enough to meet all those design requirements, early research focused on installing a nuclear reactor in a plane.

Meet the XB-70 Valkyrie, Almost the World’s First Nuclear Aircraft | Danger Room |

What if that plane had gone into production, how would air craft be different?
Discuss the article.


I’ve seen the one at the AF Museum many times. In fact, I have a picture of it somewhere (that I took). I don’t have it on my computer right now, or I would post it. That’s a gorgeous plane.


That’s kind of a double what-if. IIRC, the MiG-29 was designed to be a response to a conventionally propelled B-70. So that what-if is known to some degree. OTOH, nuclear-powered? That no aircraft in the intervening 45 years has been tried with nuclear power suggests there was some yet unresolved technical issue with nuclear power in aircraft.


I never heard anything about them considering nuke propulsion. The two XB-70 prototypes had six (each) General Electric YJ-93 afterburning turbojets.

There was once a test of a nuclear reactor aboard an experimental Convair B-36, but the reactor wasn’t used for propulsion.

Actually, it was the MiG-25. The MiG-29 was about fifteen years later.

I did notice that you capitalized “MiG” correctly! :biggrin:


Oy! I almost made it worse by posting “MiG-29 Foxbat” - the right NATO nickname for the MiG-25. “MiG” is Mikoyan and Gurevich. I’m on the run from the doctors for people who remember such stuff.


If you read the article you would see some pictures of it.


I would imagine it would be the weight of the reactor. If it were made light enough to be lifted in an airplane, I imagine the shielding would have to be a couple of layers of aluminum foil which would result in microwaved flight crews…

All kidding aside, I cannot imagine that a serviceable nuclear reactor could be made light enough to be lifted by any airframe within man’s current ability to build. Even stretching imagination that far, I cannot conceive that the airframe would then have any payload capacity, as every bit of load capacity would most likely be used to lift the power-plant. So it would be an extremely costly exercise in futility.

That’s my surmising, anyhow.


Qix did you read the article?


Actually, no. I was just sort of guessing/ funning around because the title caught my eye, but it wasn’t quite what I expected… Surely you have been here long enough to know not to take me seriously? :wink:

I’ll read it later, though. Still have a bit of other catching up to do atm.


No, I haven’t reading much of your comments to know what is the percent of your comments which are serious, and which are not. :embarrese


LOL, nothing to be embarrassed about… I don’t comment that much nowadays.

So I read the article, and it says they sent it up with a working reactor, but it wasn’t powering the airplane. No word on if it was big enough to power the plane, etc, just checking the effects of the reactor on the systems…, and they put a lead shield between the reactor and crew, which probably means the reactor itself wasn’t well shielded…

I was right the first time…it was a flying microwave :alien:


But the aircraft was pretty cool, did you ever hear of a pebble bed reactor?


I’ve heard of it, but I can’t remember the specifics…possibly mentioned in passing in one of Tom Clancy’s novels and I never knew the specifics…?

Oh, Mr. Gooooooogle, I gots a question for youuuuu!! :slight_smile:

EDIT: I do remember reading about the PBR and VHTR designs, now that Wiki has refreshed my memory a bit… I don’t understand all I know about the technology, and I don’t know squat, soooo…yeah, I’m not a rocket surgeon or a brain scientist

AND BTW: Yeah, that is one COOL (expletive) aircraft. You can definitely see the paternal resemblance to the SR71a…

Hey, Santa, I know it’s still early yet, but I think I know what I want in my stocking next year …:wink:


A pebble bed of uranium cooled by gas, that would be an excellent tank reactor.


The XB-70 was a very graceful craft, though I see more SST-Concorde resemblance maybe than Blackbird.

The two main technoid issues I could see are shielding and weight, and converting the heat energy from the reactor to propulsive power. In a ship, a nuclear reactor is used “just” for electrical power and propulsive power; buoyancy is the result of the area enclosed by the hull. In an aircraft, lift, the analog of buoyancy, is dependent on propulsion, so the power from the reactor has to overcome its weight. In practical nuclear-powered ships (e.g. CVNs, SSNs and SSBNs), the size of the ships (and therefore their drag) is dictated more by the function of the ship than by the nuclear reactor, shielding and energy conversion system. Another issue I see is in the realm of “what-if”. The need to make an aircraft light means that reactor cooling and control systems are relatively unprotected. A well-placed .50 cal. slug or 20mm shell would make for a nuclear mess, potentially killing crew and craft (and making a mess wherever it falls). Nuclear-power ships are much more robust and the reactor cooling and control systems are much more protected. Not invulnerable, just more robust.


Imagine if they had researched and figured out the kinks and the problems, and put into production… How would plane tech be different.


The problem with a nuclear reactor in an airplane would be cooling. If you can carry a nuclear bomb in an airplane, there shouldn’t be an issue with a reactor, but the problem is that you produce so much more energy than you need and in the air you don’t have a good way to bleed off excess energy. On the ground or in the water, you can supply water to absorb excess energy and expell it to the environment.


Air? Gas? Some other form of coolant?


I suspect a bigger problem would be reaction mass. You have to have it in one form or another whether for a rowboat, electric car, piston airplane, jet or rocket in order to transfer heat into locomotion. I get the impression that air isn’t too good for it, whereas water seems to be, given nuclear naval vessels.


… the problem is that you produce so much more energy than you need and in the air you don’t have a good way to bleed off excess energy.

This issue becomes worse at high altitude. Excess heat could be dissipated to the aircraft’s frame and skin, but at high altitude the air is so thin that heat dissipates to the surrounding atmosphere much less well than at sea level.