Advice Needed

[george]

Hello
I am working on a scratch build civilian submarine. The main motor is a: ERS-365S 6V Hi Torq motor, op. range 3-12v, nom. 6v, N.L 16340rpm, 0.54A, Max Eff. Speed 12340rpm, 3.40A, 100.0 g.cm torq, 12.65W, %eff.62.0, stall torq 408 g.cm. That`s ALL the specs I have on the motor.

My question is Direct drive OR Gear reduction? Before you ask why this motor, I have a small box full and why not use one. This submarine is NOT meant to be a speed demon but an average Civilian research type submarine.

Any tech. help would be appreciated, IF it should be gear reduced, where can I get the gear system?

Thanks in advance for the help.

George

[He Who Shall Not Be Named]

If the propeller is equal to or smaller in diameter of the motors can, then direct drive. If the propeller diameter is greater than the diameter of the motors can, then gear it down. 3:1 for starters.

David

[george]

Hello again

Thank You HWSNBN.

Is that a typical way to go with the motor and propeller in terms of gearing or direct drive? My propeller is bigger in dia.. than the motor. Know of any source for a small 3:1 gear unit that is not bulky, space is a factor as well as well as weight?

George

[He Who Shall Not Be Named]

Hello again

Thank You HWSNBN.

Is that a typical way to go with the motor and propeller in terms of gearing or direct drive? My propeller is bigger in dia.. than the motor. Know of any source for a small 3:1 gear unit that is not bulky, space is a factor as well as well as weight?

George

Sure.

This rule of thumb applies to most brushed can motors -- and a very sloppy fit, but works most of the time. Number of poles, voltage, turns per pole, and so on are variables that can put this process to the lie. And owing to the greater torque of brushless motors, you would modify this rule to include slightly larger propellers to can size for linking as direct-drive units.

I'm a dumb-ass when it comes to math, so, yes, this is the typical way I make the choice of direct-drive or gear chain.

Check the r/c plane catalogs for gear-reduction units. Look for the planetary type -- small of footprint but pricey.

M

[george]

Hello
Do you have stock 3:1 gear assy. laying around? I could buy 1 from you?
George

[Von Hilde]

If the propeller is equal to or smaller in diameter of the motors can, then direct drive. If the propeller diameter is greater than the diameter of the motors can, then gear it down. 3:1 for starters.
David

geeze I lernt sumpthin every day Cuzzy. You dun tilted the can in my direction oncet agin!

[He Who Shall Not Be Named]

Hello
Do you have stock 3:1 gear assy. laying around? I could buy 1 from you?
George

I used to produce them as descrete units, but now adays I incorportate the 3:1 gear reduction unit into the SD's motor bulkhead itself. Like this:



So, no I don't have any. However, Mike might still have a few in hand as he cleaned me out of the 'old stuff' a bit over a year ago.

David

[Kazzer]

yes I have some assemblies. What exactly is this to fit?

[george]

Hi Mike
I need just the 3:1 gear assy. alone so I can connect it somehow to my motor and then to the propeller. Do you have anything like that? If so, could you show me a picture of it and the price please.
Thanks Mike
George

[trout]

Maybe the gear sets here are what you want:

http://www.maxxprod.com/mpi/mpi-10a.html

or
http://www.cornwallmodelboats.co.uk/...elt_drive.html

[george]

Hello

First, Thanks to ALL for your tips and suggestions.

Now, time for a basic question, do you really need to use gear drive when my propeller is bigger than the dia. of the motor can?

George

[He Who Shall Not Be Named]

Hello

First, Thanks to ALL for your tips and suggestions.

Now, time for a basic question, do you really need to use gear drive when my propeller is bigger than the dia. of the motor can?

George

It's a question of the load the propeller presents to the motor -- high blade area, high pitch, large diameter all contribute to the torque required to rotate it. As a rule of thumb the typical marine propeller has a total developed blade area (less the hub) of between 60-75%, and the pitch is about the same as the diameter. For that type wheel, a 'typical' brushed motor of equal or slightly larger diameter is usually suitable. A larger propeller presents a greater load. Bad Ju-Ju.

Basic answer: Do you really want to burn out your motor or ESC?

Now you know as much about propeller-motor matching as I do (I barely got through high-school, so what the **** do I know?).

M

[george]

I sent a PM to Mr. Caswell a few days ago reg. some old gear assy. he has. No reply.
George

[He Who Shall Not Be Named]

I sent a PM to Mr. Caswell a few days ago reg. some old gear assy. he has. No reply.
George

Be patient. You're dealing with two old farts who's respective Warranties have expired. Takes time to crawl to the keyboard.

M

[george]

Oh HWSNBN patience is with the mature/wise. I wish I could say what I think here, I s__k at it. Thanks for ALL Your Time and Help though.

George