An F-35 does not contain 417 kg of rare earths

This is one of those numbers that is widely bandied about:

One F-35 stealth fighter jet, dubbed by defence wonks as the “flying computer”, for instance, contains around 417kg of rare earths, according to a US congressional report.

It’s bollocks. At least, I am insistent that it’s bollocks.

An F-35 weighs, unladen, 13,300 kg. There’s no way that 4 or 5% of that is rare earths. Nonsense.

I have tried tracking it down. I can find the Congressional report that states this. But not the DoD report which the congressional is quoting from. So I cannot in fact check.

But what I am sure has happened is this. That there are 417 kg of things which contain rare earths has been transformed into 417 kg of rare earths.

As an example, and not to be taken seriously as an actual detail. A “rare earth magnet” is likely to be NdFedB (it can also be SmCo, or NdDyFeB, even NdDyTbFeB). But it’s Nd2Fe14B. Forget atomic weights because that’s being boringly detailed and just run with this idea that it’s 2/17ths Nd, or 12% Nd.

So, there’s a rare earth magnet in there. We counting the 12% toward that 417 kg, or 100%? Or, we’ve an electric motor, using a rare earth magnet. We talking the 12% of the magnet, 100% of the magnet, or 100% of the ‘leccie motor? In the absence of being able to see that DoD report I insist that it’s 100% of the motor being counted.

An F-35 contains 417 kg of rare earths is one of those errors which has multiplied through the information space. I insist it’s an error. If anyone wants to prove me wrong then I’d be delighted to read that DoD report…..

12 thoughts on “An F-35 does not contain 417 kg of rare earths”

  1. The problem with getting information from people haven’t a clue about the subject they’re informing one on. Gives one great confidence on matters like Covid restrictions & Climate Change provisions. And, of course, economics.

  2. If the idjits count lithium, cobalt and nickel as “rare earth” as in the article… Then yes.. 417 kg.

    But even then it’s all parts of amalgams, ceramics, solutions, or alloys… meh…

  3. Speaking of magnets, Fender has just issued new versions of its wide range humbucker pickups originally used in its early 70s Telecaster Customs (to challenge Gibson’s humbuckers) which are made with CuNiFe magnets. The original pickups were something of a holy grail and have been unavailable for over 40 years because the supply of CuNiFe magnets dried up so production of this pickup ceased in 1979. Substitute alloys used in that dry period just did not make the same sound. As a result original CuNiFe pickups changed hands at ridiculous prices. I’m no metallurgist, but I can’t understand why it was so difficult for anyone to commission magnets using the original metals during that 40 years.

  4. . I can find the Congressional report that states this. But not the DoD report which the congressional is quoting from.

    The DoD report was probably written by someone who was familiar with the subject; the Congressional report by a Grievance-Studies graduate, or even worse – a lawyer.

  5. We all know that various rare earths are used in the alloys that make up the airframes. Rare earths would also be used in any components that use magnets such as any electric motors. There’s certainly rare earths used in all the optical components. Whether this adds up to 400kg+ is somewhat doubtful though.
    One thing I’ve often wondered though, is what they’re using to paint the airframes. Could they be using rare earths as part of a radar reflective coating?

  6. . . . a radar reflective coating?

    Radar absorption is the aim.

    The F-35 can mount Luneburg lenses to reflect radar, either for deliberately making the aircraft radar-visible (training missions, etc) or for disguising its radar cross section.

  7. @jgh: “wots a Kelvin gram?”

    Someone dressed up as a bewhiskered Victorian scientist who delivers a message to you.

  8. Pjf, you are of course quite right. The aim of the coating is to absorb radar energy.

    The early coatings on the F117 used superparamagnetic ferrofluid as part of their radar absorption material.

    There’s a lot of research into RAM using Ni-Co nanoparticles among other things and I’ve come across reference to radar absorbing alloys.
    I can see that rare earths may be involved somehow in their production in the kind of quantities that we’re talking about.
    I may even live long enough to find out more when it’s declassified in 20/30 years!

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