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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

#31

Post by jandrese »

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'm taking that 90% efficiency figure with a grain of salt since that is the paper calculation in a technology that is still very experimental.

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

#32

Post by cyberax »

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.

Yeah, no. Once it's known that it's possible to achieve, some enterprising company will quickly replicate it.

Unless, of course, it needs unobtainable levels of power.

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

#33

Post by jandrese »

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'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.

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

#34

Post by lunatuna »

temporallobe wrote: post #28
zrail wrote: post #6

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

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.

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

#36

Post by bombcar »

lunatuna wrote: post #34
temporallobe wrote: post #28

Earlier quoted context omitted.

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.

It’s one of the very few cases where I think both are great even though different and I don’t really see a way to improve either.

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

#37

Post by WhereIsTheTruth »

acdha wrote: post #17
WhereIsTheTruth wrote: post #2

[flagged]

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

http://www.savoir-sans-frontieres.com/JPP/telechargeables/En...

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?

The various "UFO" sightings are MHD experiments

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

#38

Post by imglorp »

eqmvii wrote: post #7
rektide wrote: post #3

> If power and efficiency issues are resolved, 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.

semi absurd is kinda why DARPA exists!

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.

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

#39

Post by bombcar »

rektide wrote: post #3

> If power and efficiency issues are resolved, 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 mean rockets are absurd - burn gas to throw it behind you to push off against. Works in space (the NYT regrets the error).

https://www.nytimes.com/2001/11/14/news/150th-anniversary-18...

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

#40

Post by gpm »

cyberax wrote: post #32
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.

Yeah, no. Once it's known that it's possible to achieve, some enterprising company will quickly replicate it. Unless, of course, it needs unobtainable levels of power.

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.
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