Sources for motor and control electronics

Hi,
I'm building a model submarine it will have a displacement of around 500kg and a length of 4m. Having worked out a rough idea as to the size of the motor required, 3hp.
I'm now looking for suggestions. Sites like technobots don't stock ones large enough and so I'm struggling to find an answer. Then there is the matter of how to control the speed. Ideally I'd like proportional control.
So, does anyone know where I can find a large enough motor, ideally with the electronics to control it? The onboard power will be provided for by two 12V batteries, of which the AH is still undecided.
Thanks
Michael
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On Sat, 05 Nov 2005 13:06:59 GMT, "Michael"

You're familiar with the SubCommittee, I assume:
http://www.subcommittee.com /
JM
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wrote:

Yup, but most subs are around 6 foot, not 12 foot, hence my post here and not there.
Michael
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Michael wrote:

They may still be the better source as most people here build robots in the 6-12 *inch* range. A few are up to 18-24 inches or so.
Try the companies that deal with wheelchair motors and electronics. Many of these motors are in the HP range you're looking for, and more, and they offer the control electronics for speed and reversal. Try National Power Chair for starters. Bring your wallet.
-- Gordon
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So far I've asked a submarine forum, a model engineering forum, a boat building forum and this one. With varying success
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On Sat, 05 Nov 2005 16:49:56 GMT, "Michael"

I think elevators may use large DC motors (or at least use to). I suspect their types of controls would not be very efficient for use with batterys. The rec.crafts.metalworking grup has a large following who may have come across something like you need. Railroad groups might be a resource as trollies and such might also use DC motors.
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So, not knowing much about submarines, what's wrong with the trolling motor that was suggested? It sounds like an ideal pairing of packaging and capability. Not to mention mass consumer pricing. I'm not at all sure how many pounds of thrust equates to 3 HP, but I think I can get pretty close by figuring 2.5 to 3 kW battery draw. The controller? I haven't built anything that large, but the only real difference is the power mosfets.
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$$$$$$$
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I see. WalMart is selling motors with good specs for $200. I didn't think it that bad for a housed motor complete with prop and controller. Do let us know if you manage to find a 3 hp PMDC for much less than that.
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I ve seen trolling motors on Ebay for as little as $30....
--
Thanks,

Dean Burell
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On Sat, 05 Nov 2005 15:21:20 GMT, "Michael"

How much more power do you think you'll need for a 12' vs. 6' sub? Power required to drive at a certain speed doesn't increase proportionally to the length. I don't do subs myself, but I do build model surface ships. I can tell you that getting them sca;ed DOWN to a reasonable speed is a challenge, sometimes. The motors & speed controllers that electric boat racers use produce a lot of power. I'd expect that you'd have to gear down significantly, even if you used a mild model marine motor(s) & electronic speed controller.
JM
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Electric trolling motors

the
12V
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Michael wrote:

Sure. Here's a comparison table of larger DC motor controllers for robotic applications.
    http://www.roboteq.com/comptable.shtml
Here's another comparison table.
    http://www.robotpower.com/products/compare.html
These controllers are in the 1KW to 24KW range.
                John Nagle                 Team Overbot
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Thanks for all the comments
What about:
10 1/4Hp motors, all sharing same shaft. To control, step the voltage up/down. So have 8 6V batteries, them connect them in such a way, so that the draw on each battery is the same. Very cheap, and should work. And no complex controllers to interface. Only problem is that isn't that efficient.
Michael
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Obviously big bickies involved here - if you are going to use a 24v motor then you are looking at around 80+ amps, or at 12v around 160amps
I wonder if a 24v truck starter motor would do the trick - pick one up from a truck wreckers at a reasonable price I should think.
I think you might have to look at PWM for control - a PICAXE could do the signal stuff, but you would need some BIG transistor or such etc to handle the current.
David - who doesn;t know much about this stuff, but is offering ideas
Michael wrote:

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