[oroup]

I'm fascinated by how this ended up with the same name as the fictional stealthy propulsion technology from the Hunt For Red October. They're both called "magneto hydrodynamic" propulsion.

The book was published in 1984. Was this widely theorized? Did Clancy speak to someone with non public information? Were the researchers at Duke fans of the book / movie? Did they just copy the name of his technology or did the fictional description of how it worked actually inspire their research?

[qubex]

Magnetohydrodynamics (MHD) is a real branch of physics that deals with the motion of charged fluids (which could be ions dispersed in a fluid, but more typically involve the high-temperature plasmas of stars and experimental fusion reactors). Mathematically it fuses Maxwell’s Laws of Electromagnetism with Navier-Stokes for fluid flow (if that is insufficiently nauseating, relativistic and quantised complications are available upon request).

The idea of moving water by running a current through it and subjecting it to magnetic fields was “diffusely known” in the late 1970s/early 1980s. Japanese researchers eventually built such a device in the 1990s and discovered it to be hideously inefficient. I myself knocked together a means of getting electricity out of a flame by means of electrodes and a magnetic field as a high-school science in the late 1990s. It really isn't as exotic as it sounds.

Tom Clancy isn’t actually who conceived of MHD propulsion for the fictional Red October: in his book, the boat made use of an impeller (essentially a propeller, perhaps contra-rotating, inside a cowling much a kin to a jet engine nacelle). It was only revised to be a MHD system for the film. Interestingly, impellers have now become mainstream methods of propelling a submarine, and it seems that the next frontier is to use brushless engine designs to drive the rotor by oscillating magnetic fields generated by housed coils and not need to run an axle through the pressure hull.

MHD meanwhile, as you can see, has been relegated to a supporting role of perhaps aiding stealth.

So, remarkably, Clancy was entirely accurate in his technological predictions and the later film-makers screwed up.

[oroup]

Great answer, thanks!

[qubex]

Glad to have been of service!

[mcguire]

"Mathematically it fuses Maxwell’s Laws of Electromagnetism with Navier-Stokes for fluid flow (if that is insufficiently nauseating, relativistic and quantised complications are available upon request)."

Quote of the day, too!

[positr0n]

Not related to magneto hydrodynamics, but

> Did Clancy speak to someone with non public information?

I heard from people working for DoD contractors that there was a lot of classified information around anti-submarine warfare technology and tactics in the book. This quote from the nytimes review in 1987 seems to confirm that.

Mr. Lehman, in an interview last week, recalled telling Mr. Clancy in a good-natured way: 'If you were a naval officer, I would have you court-martialed because of all the classified information in your book.' Up to that time, Mr. Lehman said, 'operational procedures of antisubmarine warfare had been classified.' But, he added, Mr. Clancy had simply ''pieced it all together by voraciously reading the open literature for 15 years, things like the Proceedings of the United States Naval Institute.''

http://www.nytimes.com/1987/08/30/weekinreview/tom-clancy-s-...

[apendleton]

This paper doesn't propose propelling the boat magnetohydrodynamically, but rather using magnetohydrodynamics to alter the movement of the water around the boat to reduce its drag. MHD for propulsion has been doable for a long time (anecdote: someone built a small MHD drive for my high school science fair). Turns out they're pretty inefficient, so not very practical.

Also, as an aside: MHD propulsion was only the mechanism that powered the sub in the movie. In the book, it was an impeller.

[robochat42]

magnetohydrodynamics is a real field of study that has been researched as a form of propulsion in water, so I guess that Clancy was just following the latest in research. A quick look at wikipedia confirms that there were prototypes made in 1965.

I did a short project on it while at university. One issue we had was that using any DC currents in salt water inevitably leads to the production of chlorine gas which isn't a great idea. We could only test our MHD motor for less than a minute before we needed to stop and ventilate the area!

[1] https://en.wikipedia.org/wiki/Magnetohydrodynamic_drive

[adrianN]

Magnetohydrodynamics was started in the 70s

https://en.wikipedia.org/wiki/Magnetohydrodynamics

A working prototype boat was built in 1991:

https://en.wikipedia.org/wiki/Yamato_1