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DARPA’s silent MHD magnetic drives for replacing naval propellers

naval-technology.com

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Re: DARPA’s silent MHD magnetic drives for replacing naval propellers

#61

Post by mikewarot »

aardvarkr wrote: post #21
gpm wrote: post #11

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…

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.

I suspect the Navy actually does have room temperature superconductors[1] ... which could make this a practical technology.

[1] https://patents.google.com/patent/US20190058105A1/en

Re: DARPA’s silent MHD magnetic drives for replacing naval propellers

#62

Post by jasonwatkinspdx »

aardvarkr wrote: post #21
gpm wrote: post #11

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…

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.

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.

Re: DARPA’s silent MHD magnetic drives for replacing naval propellers

#63

Post by jasonwatkinspdx »

atonse wrote: post #15
zrail wrote: post #6

Isn't this the plot for Hunt for Red October?

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.

Re: DARPA’s silent MHD magnetic drives for replacing naval propellers

#64

Post by edrxty »

jandrese wrote: post #33
aardvarkr wrote: post #21

Earlier quoted context omitted.

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.

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.

Re: DARPA’s silent MHD magnetic drives for replacing naval propellers

#65

Post by vba616 »

_trampeltier wrote: post #12

Yamato-1 looks so fast. I saw this ship in Kobe and i felt like in a Science Fiction movie. But .. > these ships were only able to reach speeds of 15 km/h. https://en.m.wikipedia.org/wiki/Yamato_1

The 70,000 ton Yamato battleship could go 50 km/h circa 1940:

https://en.m.wikipedia.org/wiki/Yamato-class_battleship

Re: DARPA’s silent MHD magnetic drives for replacing naval propellers

#67

Post by mrDmrTmrJ »

mikewarot wrote: post #61
aardvarkr wrote: post #21

Earlier quoted context omitted.

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.

I suspect the Navy actually does have room temperature superconductors[1] ... which could make this a practical technology. [1] https://patents.google.com/patent/US20190058105A1/en

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

https://patents.google.com/?inventor=Salvatore+Cezar+Pais

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...

Re: DARPA’s silent MHD magnetic drives for replacing naval propellers

#68

Post by bruce343434 »

> 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.

Re: DARPA’s silent MHD magnetic drives for replacing naval propellers

#69

Post by andkenneth »

bruce343434 wrote: post #68

> 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.

There is passive sonar too, which is just listening.

Re: DARPA’s silent MHD magnetic drives for replacing naval propellers

#70

Post by fl7305 »

bruce343434 wrote: post #68

> 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.

A submarine is like a ninja. It tries to sneak around undetected.

Using active sonar is like placing a siren on your head.

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