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[U-33]

Right chaps, more of your invaluable advice wanted, please...


I need a motor for X9..a dynamic dive boat. The motor needs to be 540 sized, able to run on a 7.2v 3700a/h nimh pack, able to turn a 40mm 3 blade brass prop, give me a reasonable running time, and have enough poke to drive the sub under. She will be trimmed right down to decks awash, so she won't need too much power to submerge.


Over to you...recommendations/advice gratefully received.

[Klunk]

Go brushless. Get a torque motor. Gives you the choice of batteries ie lipo which are lighter with higher  mah. Not sure on size red but I'm sure Andy will be along soon.

[U-33]

No...don't want brushless. That means all new esc's and lipos, neither of which I'm particularly fond of. A decent brushed motor and a set of nimhs...I'm happy with them.

[Klunk]

Fussy old git!
Johnson 600?

[Klunk]

And I must get them damn plans sent off to you

[U-33]

No rush, old chap... 

[Bob K]

No...don't want brushless. That means all new esc's and lipos, neither of which I'm particularly fond of. A decent brushed motor and a set of nimhs...I'm happy with them.

Not just me then.  Unless you want 90 knots, a 30 sec battery life, and to spot your ship by the Pillar of Smoke that indicates the battery has run out.

[U-33]

I'm told I'm an old fart, a dinosaur, and a candidate for the Antiques Roadshow...but I like what I know. I prefer a radio box over a cylinder, and I like brushed motors and nimh batteries.   

[unbuiltnautilus]

Etronix 60T, ET0313. Available from all good CML Distribution stockists.

Just got two of these in for a Darnell/Models By Design/Mountfleet* Type VII U-Boat. Dont like the MFA RE540-1, too sparky, Johnson 600s only good for fast set ups or with big reduction gearboxes, and Graupner have stopped doing anything useful!
So these motors are designed for Rock Crawlers hence the 60T, which indicates the number of turns of copper around the armature, the more turns the slower the motor. As a guide the old Chart/Micromold RS550 had 32 winds, and a typical buggy motor ( of the time! ) had a 27 turns, they are now more typically 15 to 20 turns, don't put these in your fishing boats please!
Got one out of the pack today, very high torque, 1 amp off load and between 2.5 and 3 amps on load. Scientifically proved by running the motor shaft hard against a piece of timber till it slows down about as much as you would expect with a prop on it!!
I think the 60 Turn motor could turn a 45mm prop direct drive, at a push and at about 3 to 3.5 amps. Smaller prop, lower current.

All for £16.99.

Cheap Chinese versions available from the usually sources!

* Mountfleet do a most excellent late conning tower for the Type VII with the extended AA platform, nice...

[U-33]

Now that's what I call a recommendation...thanks for that skip, much appreciated.


I have been recommended to use a 385 motor over on the F/B Dive In page, I've got plenty of those...but I only want to do this once. I've put motors in subs before, then discovered I'd made a wrong/bad choice, and had to end up destroying half the boat to change them. I'm too old for that nowadays, I want to fit the motor, button down the hatch, and go sailing!


My Onondaga had two 380's in it, and that was a big heavy boat...that worked a treat. The X craft is half that size, and will be running at decks awash anyway. I can't remember what I used in X22, but that would run for ages on one charge.


I'll go check your Etronix motors out...thanks again mate, good of you.

[U-33]

Ooh...just thought...I have a Carson Poison truck motor...any good?


BTW...is this the motor?


http://www.modelsport.co.uk/etronix-sport-tuned-modified-brushed-motor-60t/rc-car-products/37820

[unbuiltnautilus]

That's the beast, cheaper too. Don't tell my mate with the U-Boat!

I used a big low rpm 540 can motor on a Deep Dive 6 all those years ago when they were new. Spent most of the time throttling back when underwater as it was still too fast, so there may be some mileage in your 385 motor choice. depends on prop size though. I would probably not exceed 35mm with a 385 just in case. also if you are static diving, you don't need much power, if dynamic diving, use a bigger motor and throttle back when under water.

Still, I think these rock crawler motors are the discovery of the day. If I didn't have Pittmans buried deep in my U-Boat, I would swap them out in a heartbeat

[U-33]

Thanks again, skip...X9 is to be a dynamic dive boat, so I'm thinking I'll have enough steam with a crawler motor, as you say, get her under and throttle back.


Cheers, m'dear...