Very cool, and although the submarine may be silent, the magnetic anomaly could theoretically be detected and tracked.
It won’t be completely silent because you’re still jetting a lot of water out the back of the submarine.
DARPA’s silent MHD magnetic drives for replacing naval propellers
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Re: DARPA’s silent MHD magnetic drives for replacing naval propellers
#42This 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.
Re: DARPA’s silent MHD magnetic drives for replacing naval propellers
#43Isn't this the plot for Hunt for Red October?
It’s Tom Clancy’s future, we just live in it.
Re: DARPA’s silent MHD magnetic drives for replacing naval propellers
#44I 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.
Re: DARPA’s silent MHD magnetic drives for replacing naval propellers
#45I wonder if it sounds like whales humping or a seismic anomaly…
You’ll just have to speed up the recording to 10x to find out… :)
Re: DARPA’s silent MHD magnetic drives for replacing naval propellers
#46I wonder if it sounds like whales humping or a seismic anomaly…
Ask Jonesie
Re: DARPA’s silent MHD magnetic drives for replacing naval propellers
#47> 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...
That's very true, but "efficient" isn't usually an adjective thrown at a rocket.
Re: DARPA’s silent MHD magnetic drives for replacing naval propellers
#48This 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.
Wikipedia has some numbers - obviously there could be a difference between them and reality but they are a plausible starting point.
https://en.wikipedia.org/wiki/Magnetic_anomaly_detector#Oper...
Re: DARPA’s silent MHD magnetic drives for replacing naval propellers
#49Earlier quoted context omitted.
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.
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.