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Michael posted on November 5, 2005, 1:06 pm
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
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
John Mianowski posted on
Re: Sources for motor and control electronics
You're familiar with the SubCommittee, I assume:
http://www.subcommittee.com/
JM
Re: Sources for motor and control electronics
Yup, but most subs are around 6 foot, not 12 foot, hence my post here and
not there.
Michael
Gordon McComb posted on
Re: Sources for motor and control electronics
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
Re: Sources for motor and control electronics
So far I've asked a submarine forum, a model engineering forum, a boat
building forum and this one. With varying success
Si Ballenger posted on
Re: Sources for motor and control electronics
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.
Mike Young posted on
Re: Sources for motor and control electronics
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.
Re: Sources for motor and control electronics
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.
Dean Burell posted on
Re: Sources for motor and control electronics
--
Thanks,
Dean Burell
Re: Sources for motor and control electronics
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
blueeyedpop posted on 
John Nagle posted on
Re: Sources for motor and control electronics
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
Re: Sources for motor and control electronics
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
quietguy posted on
Re: Sources for motor and control electronics
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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