If they meet their 90% efficiency target, that's exceeding the efficiency of a normal boat. Just the propeller losses are higher than that (at ~80% efficient [1]).
If it's just some REBCO super-conducting magnets and conductive surfaces it might be reasonably inexpensive too. And without moving parts it could be a maintenance win as well.
I'm no sailor, but at first glance this seems like it would potentially replace all propulsion on boats/ships big enough to justify cooling REBCO. Obviously conditioned on actually reaching that fairly outrageous target.
MHD is nothing new though, so if it has not yet replaced propellers I'm guessing it is because of practical issues like corrosion, electrolysis and so on alluded to in the article that DARPA seems to have found solutions for but which are not going to be available for the general public for obvious reasons.
Also it's all electric so it poses the usual problems like the added complexity of an on-board electric generator or the added weight and cost of a battery system.
Like fitting supercooled tesla-power magnets to a moving vehicle, perhaps.
> the added complexity of an on-board electric generator
But you don't need that if the vessel is electric-powered, like a nuclear-powered sub; and I believe some modern warships use a traditional motor to drive a generator, which drives an electric motor for propulsion (i.e. an electric ship powered by a fossil-fuel generator).
> But you don't need that if the vessel is electric-powered, like a nuclear-powered sub
Yep.
> I believe some modern warships use a traditional motor to drive a generator, which drives an electric motor for propulsion
Sure, like a diesel-electric locomotive.
It turns out in some situations it's better to eat the conversion loss from electric generation rather than using a direct mechanical linkage, because then you can use flexible cables and electrical control systems rather than a bunch of mechanical folderol
Per the article the previous generation was only roughly 30% efficient, which makes it just not competitive with propellers.
Swapping out your diesel motor with rotating shafts going through your hull and an alternator to generate electricity for a diesel generator that just generates electricity is reducing complexity, not adding it.
the alternator is already there, too, since modern diesel submarines are actually diesel-electric submarines, able to charge batteries with the diesel engine and then shut it off and run from the batteries to go quiet
so, the difference is between props vs. no props, which is big.
I agree that an innovation of this magnitude would have a huge impact on naval propulsion if it were publicly available though I’d imagine the tech would be locked down to a ridiculous level. It’s likely destined to only appear in nuclear submarines.
Well, people are talking about 90% efficiency up-thread. You can't need unobtainable levels of power and still have 90% efficiency, as people move boats around every day.
Also, about the need for a coolant, well, the fixed costs for it are on the order of a few $100/m on most cities nowadays. If people start to use lots of it, the fixed costs will fall to zero. (The variable cost isn't high, but it also doesn't dictate the boat size.)
You can absolutely have an energy requirement cliff that has to be exceeded for a thing to work before you can even measure it's efficiency. Trying to push something from standstill vs. keeping it moving.
If it needs unobtainable levels of power, that means it's not efficient. If it's efficient you can use a diesel generator in place of your diesel engine and obtain the same amount of power.
Not quite. It might be efficient, but only if you need megawatt-level propulsion power.
This is not uncommon in engineering in general. There are many, many examples of devices that are highly efficient but only at higher power levels/speeds.
The government can and does lock down intellectual property for national security reasons.
The US government effectively locked down Juliet Marine Systems' IP, and gave the inventor no compensation for doing so. Took about more than 5 years for the inventor get any relief.
The US government won't be able to lock down a company in Sweden or Turkey. It's not like the principles of MHD propulsion are in any way secret. It's just that we now have much better superconducting magnets.
There's no reason to assume that. A ton of things DARPA pathfinds are commercialized, including the globe spanning network we're using to converse atm.
I'm not sure it would be restricted so much as just way too expensive to be practical. There is also the practical considerations of generating 20T magnetic fields out in the real world and around people.
Yeah, that seems to be the way it always goes. It's not actually all that difficult to build an AESA radar in your garage, it's just very hard to get enough of the types of parts needed for a useful one without nation state level funding. The FPGAs they use are on Digikey....for 5-10k ea.
Or on the vessel itself it would have to be shielded for the people and for any equipment.
I've seen experiments where a device using a paddle was put against a person's head and a strong magnetic field emitted. It was a TV reporter for Discovery Channel Canada and her jaw convulsed, she did not look pleased.
I think the experiment was about spirituality of all things. How to induce a feeling of a presence to a person. I believe it was called the God helmet but in the video I saw it was a paddle.
"Trans-cranial magnetic stimulation" — it has both been called "the god helmet" and has been used in that way.
IIRC it's a pulsed field to induce electric fields in your brain, and also has an extremely short range.
Somewhat more significant to human health is that magnetic material can be rapidly drawn towards the magnets, with the force on a steel office chair can exceed its own structural capacity in standard medical magnetic equipment: https://youtu.be/6BBx8BwLhqg
At very high field strengths, you also need to account for "your blood is electrically conductive, and electrical conductors resist motion when in a magnetic field due to induced electrical currents". According to test subjects, this "tingles".
At the most extreme fields strengths we can currently make, you also have to account for the water in your body being diamagnetic and repelling the magnets, but we can't ask any of the test subjects what that feels like as they were a frog and a rat because that's all that would fit in the tube.
Google scholar shows that that patent 'author' has three patents
1. Piezoelectricity-induced High Temperature Superconductor
2. Craft using an inertial mass reduction device
3. High frequency gravitational wave generator
And I think with those three "inventions" one could construct a space-ship that could travel to Alpha Centauri at a meaningful fraction of 'c'.
Extraordinary claims require extraordinary evidence. Whatever is going on here, it's hard to take this document as evidence for a working room temperature superconductor...
Yes! I was thinking that as I read it. Alec Baldwin even says magneto hydrodynamic drive.
Yet another example of Tom Clancy’s incredible knowledge of the intricacies of what the military had on their radar and working that into great stories.
Magneto Hydrodynamic Drives have been a publicly researched concept since the 60s. Magnetic pumps are used routinely in industry. You're definitely exaggerating how visionary Clancy was.
I'm not talking about him coming up with the ideas. But him weaving it as a thing the US Navy had been concerned about the Soviets building – I am saying it's very likely that the US Navy's concern about these drives being used in subs wasn't made up, and maybe some related conversations he had with contacts/sources, that turned out to be one of many seeds that made for a compelling story.
I recently re-read The Hunt For Red October, and what struck me was that there actually wasn't and mention of Magneto-hydrodynamic drive. As I recalled, the book describes a series of propellers in a duct. Certainly interesting for isolating sound, but it struck me as much more simplistic from the superconducting systems described in the movie.
No shade intended towards Mr. Clancy however. I got the impression that he was quite lauded for not simply describing tech (which other thriller writers did as well) but getting into the nuts and bolts of how they operated. That was what really set him apart.
For example, it says the US "looked at this back in the early sixties and got to the model stage before dropping it. One of the things they discovered is that one impeller doesn’t work as well as several. Some sort of back pressure thing."
> The movie is a nearly faithful depiction of the novel even though there are many deviations, including Red October traveling up the Penobscot River in Maine to dry dock, the omission of the Royal Navy task force including Ryan's time aboard HMS Invincible, and the "caterpillar drive" being described as a magnetohydrodynamic drive system, essentially, "a jet engine for the water", rather than a drive powered by a series of mechanical impellers inside flow tunnels.
It was actually the first "adult" book I read. Maybe when I was 9? I told my father I was bored of school books, and he handed it to me.
As well as Clancy's other stuff!
Just stop reading at 2000 (last recommended book: The Bear and the Dragon). After that he started phoning it in / lending out the name as ghostwritten brand.
Beat me to it. Happens to be my favorite movie, ever. I’ve watched it so many times and I’m still not sick of it. What’s so beautiful about it is that it’s pure storytelling without a preachy agenda, though the irony is that it’s very much about politics and patriotism.
The book is even better. I watched the movie about a half dozen times before I read the book and was amazed that I liked the book more. And I still think the movie is great.
"The thing about a new propulsion system, Captain, is its silence... and you don't have to touch a thing. It's all moved by electric currents and magnetic fields. Just one more step towards making submarines even more silent. The next 'Red October', if you will."
“If we meet the right shot, this will work. If we get some… buckaroo?…”
He needed someone on the US side to figure out he was defecting and meet him with a plan to help. He gave it 1 chance in 3. Loved that moment you reference when he realizes he did indeed meet the right shot.
The book has ducted props (which is where the distinctive noise comes from, a unexpected resonance from the length of the duct), the movie substituted MHD for the impeller.
This is probably classified, but just how sensitive are MAD systems? A football field ship is a big chunk of metal and we’re ankle to detect them at some depth. One that has a 20 tesla magnet seems like painting a target on your own aft.
I remember this technology being a plot point in a Clive Cussler novel, and then being standard issue on new boats in most Cussler novels after that. I see Tom Clancy also featured it in his books even earlier. It’s always cool when you first learn about some tech from near-future action novels and then later that tech becomes real; feels very futuristic.
By using AC you can induce current in the water and avoid the need for electrodes, but low efficiency. By using high strength permanent magnets they can trade those.
My gut feel is that this is a pretty grossly inefficient system by nature. Inducing current in seawater just to give magnetic traction something to push off against seems semi absurd.
I understand. They're the only orbital game in town, and will be until <INSERT_PET_FUTURISTIC_THINGY>. I guess what I'm, saying, it's more that "efficient" isn't a word that pops up in your head when you imagine "rocket". It's like a demure Dodge Hellcat owner, or a contemplative WWE star.
What? VLSI, VHDL, Multics, Hypertext, GaAs semiconductors, autonomous navigation, GPS, and packet switched networking were a few things they funded. Totally absurd, right? For every successful tech, they probably explored scores that didn't pan out. Basic, high risk research has huge payoffs across society even if you don't like who's funding it or why.
So true. I read once that fundamental physics research on quantum tunnelling in Japan resulted in antennas that immediately reduced satellite dish sizes from meters across to the size of a dinner plate. Now you can connect with a modern smart phone.
Purely-electric devices tend to have this property that if you maximize or minimize something with no clear theoretical limitation, your efficiency grows all the way to 1.
On the case of this, my gut feeling tells me that making the magnet really, really big will do it.
> The MHD drive does not have moving parts, reducing noise and vibration, making it harder to detect via sonar
Uh what? Sonar is active detection, using the bouncing of emitted sound waves, no? Then I don't see how a silent engine makes it harder to detect via sonar if the signals will still bounce just as hard from the hull.
What you are describing is active sonar. The downside of active sonar is that it also clearly reveals your own position.
As such, modern submarine warfare relies mostly on passive sonar - very sensitive microphone arrays (sometimes towed behind) to listen for audio signatures of surface and subsurface ships.
This means that submarine navies (and anti-submarine surface fleets to some degree) put a high priority on the ability to run quietly. A lot of work is put into things like propellor design to minimise the noise but there's a limit to how far you can go to eliminate cavitation and other noise sources. MHD, which would just be water flowing through a pipe, can potentially be much quieter.
Relevant to this: unimaginably vast amounts of effort have gone into making propellers a little bit quieter so they are harder to hear while still allowing reasonably high speeds. A lot of that is to do with avoiding cavitation at the prop tip, which is a) noisy, and b) very destructive. no prop, no prop noise...
Since we’re already this deep into science-fiction, could we superheat air and then run the plasma through this in order to create a land or air vehicle with no moving parts?
I doubt this would be practical taking into account how strong magnetic field has to be.. I am wondering... am I missing something or nobody seriously thought about it?
You don’t need to cancel it. Most electromagnetic surveillance systems have detection thresholds (e.g. in radar you have distance gate and return signal filters). Same applies for magnetically activated mines. Reducing the signature below detection thresholds is often enough. Alternatively masking the signature with another signal to confuse the detector also often works well.
EDIT: on second thought, if you can build a device to generate 20T you can probably build a contraption to cancel it out as well. It would most likely boil down to the economics or the scale of the contraption required.
Do you have a more credible citation? That guy on YouTube seems to be the most common source for this claim and he gets paid for clicks. More mainstream sources don’t seem to think Russia has any particular edge here.
He worked on MHD, he knows what he is talking about, he also worked closely with Russian scientists, not something mainstream media would cover, specially nowadays
Anything that'd destabilize a country is generally not publicized by the press, unless it benefits you
He started a non-profit, distribute all of his work for free, and pays for translations in multiple languages, I don't think he does any of this stuff for the money
The fact that the US pretends to be pioneer in the field says it all, don't you think?
My post got flagged, so there can't be any more discussion about it, that's unfortunate, but I can understand why, and it make sense, not enough "mainstream" proof, I'll try again once I can find more presentable evidence
If it's just some REBCO super-conducting magnets and conductive surfaces it might be reasonably inexpensive too. And without moving parts it could be a maintenance win as well.
I'm no sailor, but at first glance this seems like it would potentially replace all propulsion on boats/ships big enough to justify cooling REBCO. Obviously conditioned on actually reaching that fairly outrageous target.
[1] https://www.britannica.com/technology/naval-architecture/Act...