Talk:Magnetohydrodynamic drive

message: You probably would be unable to stop electrolysis occuring. But, I can reason like this:
1. While you are right in that the hydrogen + chlorine reaction is explosive, it only happens if there is available light. In the dark (e.g in an engine) there is absolutely no reaction.
2. Chlorine itself is not corrosive. It reacts with water to form hydrochloric acid and hypochlorous acid, which are. However, in an MHD, the dilute acidic solution would be rapidly ejected from the engine into the sea, whre it would do no harm to the engine.
You are right in that the hydrogen bubbles would remain free, but they may be collected and stored/used.
82.153.169.213 17:44, 13 October 2005 (UTC)
thread_title: Electrolysis reply

message: The Red October's Caterpillar drive was thermohydrodynamic, not magnetohydrodynamics, or in other words a nuclear water jet. One thing I never really understood was how they avoided cavitation from boiling water. Then theres also the issue of running the reactor hot enough to heat huge volumes of water at an extremely high rate of speed, if anything went even slightly wrong it would melt down and explode before they even knew what happened.
Magnetic detection is a problem for all subs and I'm not sure a MHD drive would make a difference, certainly wouldn't help. Using different hull materials or layers of materials is another option. It would sacrifice dive depth and general hull strength for increased stealth. Same for acoustic detection, a soft enough material might even be able to adsorb an active sonar ping (e.g. creating a large shadow or “hole�? in the water rather than a well defined shape).
Few literate among these had been made on the spite of the listening with respect to the willingness ok..Other things to consider with next generation subs: hyper-planing rocket propelled torpedoes and hyper-planing bullets. Deep running subs are effectively immune to missiles, bombs, depth charges, etc... Now with hyper-planing bullets they could easily destroy an incoming conventional torpedo well before it poses a serious threat to the sub. Hyper-planing torpedoes allow the sub to hit targets well outside of detection range with a supersonic torpedo that cannot be detected before impacting the target. (note, saying next generation is a bit of a misnomer, China armed their subs with Russian hyper-planing torpedoes over a year ago but last I heard the US is planning to implement them in the next generation of subs towards the end of the decade -- not to mention these 'super torpedoes' are able to carry nuclear warheads).
Back to the subject at hand, another interesting application for MHD drive systems is fighter subs. With advances in fuelcell technology or even compact nuclear reactors, a fighter size sub could run totally silent and kill targets with near impunity (unless the target had hyper-planing bullet based weapons). Just have to work out the technical issues with the drive systems.
The future of naval warfare will be very interesting indeed and I think MHD drives will be a corner stone in that future.
-MegaBurn
In the first sentence you call it a nuclear water jet. But what could possibly be a nuclear water jet? The only thing a nuclear plant can produce is heat, which has to be further processed to get electricity or mechanical power. Your statement doesn't make sense.--Titeuf24 (talk) 01:57, 5 July 2009 (UTC)
thread_title:  Few MHD comments... 

message: I'd say yes to this merge, afterall they're the same thing. One just uses a puncher name (designed to inspire the imaginations of film goers) and the other a technical name. --62.173.194.7 08:05, 24 July 2006 (UTC)
replies: text: The caterpillar is the underwater equivalent of a jet, not an MHD. Like in all conversions(I just know I'm using the wrong word), details were changed when the screenplay was written. In the book(which should always be preferred over the movie in this kind of situation), the caterpillar is driven by impellers. The article needs to be rewritten to show this. BioTube 00:28, 24 September 2006 (UTC)
thread_title:  Merge with [[Caterpillar drive]] 

message: "The major problem with MHD is that with current technologies it is more expensive and much slower than a propeller driven by an engine. The extra expense is from the large generator that must be driven by an engine. Such a large generator is not required when an engine directly drives a propeller."
So, if it's still driven by an engine powering a generator...what's the point of the MHD?  —Preceding unsigned comment added by 146.145.251.34 (talk) 20:16, 23 November 2010 (UTC)
thread_title:  Clarify the engine/generator part? 

message: Magneto-hydrodynamic Propulsion was first used in experimental German submarines in 1933.  The Germans also tried it to propel torpedoes, but the gases produced were visually more noticeable and they were very acoustically noisy, as well, so this was abandoned in favour of chemical propulsion in which the reaction products were dissolvable in seawater to conceal the wake.  They could not get sufficient thrust from this, so they returned to using propellors and put up with the cavitation wake they produced because they were so much faster, which meant that the target had insufficient time to react.  The Magneto-hydrodynamic propulsion of submarines was similarly abandoned because of the acoustic and magnetic noise and because low RPM propellors and electric motors were far less detectable.  — Preceding unsigned comment added by 203.142.148.196 (talk) 02:26, 31 December 2011 (UTC)
thread_title:  History of Magnetohydrodynamic Propulsion 

message: Substituted at 22:50, 29 April 2016 (UTC)
thread_title: Assessment comment

message: The lede says "MHD drives remain impractical due to... the large amount of energy needed to operate them," implying that efficiency is low.  But the article says precious little about actual efficiency.  It would be nice to have a section, however brief, that describes MHD efficiency.
The article goes on to say "The major problem with MHD is that with current technologies, it is more expensive, and much slower, than a propeller driven by an engine. The extra expense is from the large generator that must be driven by an engine. Such a large generator is not required when an engine directly drives a propeller."
As written, this is dubious.  A diesel-electric locomotive is not driven directly by an engine;  instead, a diesel generator creates electric power which drives electric motors.
Now, there may be a valid reason why the need for a generator is not a problem on a locomotive, but is a deal-breaker on a marine vessel.  If so, the article should explain it. Novel compound (talk) 21:35, 17 September 2017 (UTC)
thread_title:  Supposed reasons for impracticality -- a generator and (possibly) low efficiency 

message: This article contains some good, sourced material, but mixed in with that much of it is unsourced speculation reminiscent of science fiction. Examples will follow. Andrewa (talk) 22:52, 12 April 2020 (UTC)
thread_title:  Fact or fiction 

message: Electromagnetic Flowmeters measure flow of conductive fluids with no moving parts using the MHD Generator principle.
https://en.wikipedia.org/wiki/Magnetic_flow_meter — Preceding unsigned comment added by 194.54.168.71 (talk • contribs) 12:10, 25 February 2021 (UTC)
replies: text: Not really. ~Anachronist (talk) 18:07, 25 February 2021 (UTC)
thread_title:  Electro Magnetic Flow Meter 

message: It says:
"Active flow control by MHD force fields on the contrary involves a direct and imperious action of forces"
"Imperious"? How can a force's action be imperious? Can anyone say whether perhaps there's a typo, and some other word was intended? 
MrDemeanour (talk) 14:55, 26 May 2023 (UTC)
thread_title:  Active flow control