Sunday, March 20, 2011

Re: [Electric Boats] What is the optimum shaft speed?

 

John,

The slower the prop speed the better. Larger the prop the better.  Some will say square props are best.  Take note of the thread on motor cooling for details on the major problem running motors slower than what is needed to cool the windings.  Disconnecting the fan from motor speed is the best way to cool a motor that may run at a speed slower than what is needed to cool a motor.

Kevin  Pemberton

On 03/20/2011 07:37 AM, John Green wrote:

 


2 Quick 'Opinion' Questions!

1 - What is the 'best' max speed to have the shaft running at?

note- I will be starting by using a standard style prop that was driven
by a direct drive Atomic 4, but might also experiment later with thinner
high aspect props - in other words I want quick general answers, not
specific to various setups. (I am trying to design something
uncomplicated with 12 to 24 volts, belt drive, and need to look at
pulley sizes available.)

2 - are there any snags to rotating a dc motor with no load on the
wiring?

I know that it will act as a generator, but will there be snags like
internal heat being produced in some way?
(I am looking at multiple smaller motors and want to know what I can
safely do while fiddling with it all)

Thanks,
John


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