Electrodynamic thrust

Post by **Sea Skimmer** » 2003-06-28 02:03pm

Just how practical/possibul is this technology currently?

kojikun · Post by **kojikun** » 2003-06-28 02:09pm

considering you provide no information about it at all..

Post by **Sea Skimmer** » 2003-06-28 02:17pm

kojikun wrote:considering you provide no information about it at all..

I'm figuring anyone who would know how practical it was also would know what it was. In the original form it was considered as a submarine propulsion system. A line of electromagnets would be mounted on the boats centerline while lines of electrodes mount on either side. You pass a current through the electrodes to set up a big magnetic field. It's my understanding that this field then interacts with the earth's magnetic field to provide propulsion. However it didn't work for subs because it was quite weak and because the system wants to push you upwards. Not real good for a sub but possibly useful for a satellite or spaceship.

kojikun · Post by **kojikun** » 2003-06-28 02:26pm

Oooh! Ok. I don't think thats called electrodynamic thrust, because when I googled electrodynamic thrust I got a lot of websites on the electrodynamic space tethers.

Ok, you're talking about using the geomagnetic field as an outside field and creating Lorentz force within the field in order to push the object outward. Well, the technology is shit right now for two reasons: power source and magnets. We simply don't have enough power in a small enough package to run a magnetic field as large as the one required, and we don't have electromagnets cheap enough to run that much electricity through them without wasting it away on heat. A micro nuclear reactor and superconducting cable would help, but we don't have those on any applicable scale.

Warspite · Post by **Warspite** » 2003-06-28 04:00pm

The technology is still way off, there is still the lack of a proof-of-concept vehicle (I think, haven't heard anything about it, though, only projects), and the necessary maturity of all system components to be reliable aboard a ship.
Besides, the concept germinated during the Cold War, and when defense budgets were bottomless, is there a need for an ultra-ultra-silent vehicle today?

SyntaxVorlon · Post by **SyntaxVorlon** » 2003-06-28 05:24pm

Don't expect to be riding in your very own Zion class Osiris anytime soon, or EMV.
The idea is based on the idea that one could produce enough EM energy to push against the earth's mag field, but the polar nature of magnetism complicates that to no end.

kojikun · Post by **kojikun** » 2003-06-28 05:30pm

SyntaxVorlon wrote:Don't expect to be riding in your very own Zion class Osiris anytime soon, or EMV.
The idea is based on the idea that one could produce enough EM energy to push against the earth's mag field, but the polar nature of magnetism complicates that to no end.

Its not that, vorlon, its just eh power reqs. The concept is basically the same as a rail gun, only minus the powerful external field replaced with a wimpy external field. That translates into massively overpowered internal field.

SyntaxVorlon · Post by **SyntaxVorlon** » 2003-06-28 05:33pm

Too bad you can't invert a torus. Or direct most of the energy in a single direction without the backlash.

kojikun · Post by **kojikun** » 2003-06-28 05:57pm

SyntaxVorlon wrote:Too bad you can't invert a torus. Or direct most of the energy in a single direction without the backlash.

How does a torus enter into this??

SyntaxVorlon · Post by **SyntaxVorlon** » 2003-06-28 07:10pm

A torus has a purely internal field, if you could invert the effect somehow, it doesn't have to be a torus, just a different way to control the field, then you could make the field completely external and save on power and not have to worry about heavy internal fields and even worse flux.

kojikun · Post by **kojikun** » 2003-06-28 07:37pm

doesnt matter tho. the magnetic field to provide lorentz force needs to flow in the appropriate direction which only comes from linear fields (those around straight wires) not curved fields from coiled or wrapped wires.

kojikun · Post by **kojikun** » 2003-06-28 09:10pm

btw, does anyone know Lorentz force equations relevant to this problem?

Admiral Valdemar · Post by **Admiral Valdemar** » 2003-06-28 09:14pm

Are we talking magnetohydrodynamics here?

kojikun · Post by **kojikun** » 2003-06-28 09:20pm

we're talking about using the earths magnetic field as a force with which to interact and push against in order to reach orbital speeds.

Admiral Valdemar · Post by **Admiral Valdemar** » 2003-06-28 09:44pm

Hmm, sort of a related principle technology.

You mean like anti-gravity almost, a propellantless propulsion system? Reminds me of the WotW movie tripods, no legs bar the three EM beams that levitated the machine.

By the way, nice new sig quote, kojikun.

kojikun · Post by **kojikun** » 2003-06-28 09:47pm

yeah kind fo antigravity. more like maglev using natural geomagnetic fields. the concept doesnt work because you need massive amounts of power to get the things running. Massive meaning "vaporizes metals".

Post by **Sea Skimmer** » 2003-06-28 09:54pm

So the concept could work if built out of unobtainium?

Admiral Valdemar · Post by **Admiral Valdemar** » 2003-06-28 09:57pm

The MHD principle Sea Skimmer mentioned was also used in the film version of The Hunt For Red October (and like he said, it would be quiet but a decent MAD would pick the sub up no problem, catching it is another thing).

I believe MHD generators have been used on sats for some principle power tests on the technology (not as propulsion) but I could be wrong, given it's 0300 hours I probably have no idea what I mean.

kojikun · Post by **kojikun** » 2003-06-28 10:05pm

Sea Skimmer wrote:So the concept could work if built out of unobtainium?

Nah just some cheap high temp superconductors and a dense powersource.

Howedar · Post by **Howedar** » 2003-06-28 10:14pm

I believe the Japanese have a test boat for this that can make like (IIRC) 3 knots or something.

Admiral Valdemar · Post by **Admiral Valdemar** » 2003-06-28 10:24pm

Howedar wrote:I believe the Japanese have a test boat for this that can make like (IIRC) 3 knots or something.

Correct, it was a small test prototype to see if the theory worked in practice, a sub using such a system would need a far stronger EM field, or to be floating in metal.

Next generation aircraft may have such a system for propulsion or power depending on what happens to research.

kojikun · Post by **kojikun** » 2003-06-28 10:26pm

links links links!

Arrow · Post by **Arrow** » 2003-06-28 10:40pm

Do a search for magneto hydrodynamic drive and you should get a lot of info. I did a high school report on this back in 96 and I had lots of info to play with it. I do remember that it was the Japanese that were doing most of the research, but the US had built a huge test lab for the device itself (the version the US had wasn't going to be mounted on a ship, as I recall).

I think the biggest problem is power, since your trying to use water and a magnetic field to propel a ship. I'm taking a shot in the dark, but maglevs probably have higher efficiencies.

kojikun · Post by **kojikun** » 2003-06-28 11:38pm

i searched. nothing

heres an idea, just incase: what if you tried charging the water??

Post by **Sea Skimmer** » 2003-06-28 11:46pm

Admiral Valdemar wrote:The MHD principle Sea Skimmer mentioned was also used in the film version of The Hunt For Red October (and like he said, it would be quiet but a decent MAD would pick the sub up no problem, catching it is another thing).

I believe MHD generators have been used on sats for some principle power tests on the technology (not as propulsion) but I could be wrong, given it's 0300 hours I probably have no idea what I mean.

A Magneto Hydrodynamic (MHD) generator drive and an Electrodynamic thrust (EMT) drive are not the same and work quite differently. MHD's only work when they have water to pump amoung other things. Red October had an MHD and indeed the west thought the Typhoon really did have such a drive, thus the massive size but only 20-missile armament, for some time.

As it turned out that massive size was mainly to allow the boat to bit on the bottom for a year, then launch onboard satellites to disrupt the West's recovery after a nuclear attack by other assets.