[PSUBS-MAILIST] Alan needs a motor

[hank pronk via Personal_Submersibles]

Alan,
I am not talking about a hub motor, the motor I am looking at is in the 3 to 4 in dia range.  
Hank--------------------------------------------
On Thu, 10/30/14, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Subject: Re: [PSUBS-MAILIST] Alan needs a motor
 To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
 Received: Thursday, October 30, 2014, 4:22 PM
 
 Thanks
 Hank & Graham.I am
 probably searching for Nirvana here.First I
 am set on finding a brushless motor
 solution.I spent
 multiple hours of Googling, focusing on E-bikes, scooters
 etc.The
 E-bikes are mainly hub motors that are narrow with a large
 diameter, whichis no
 good as far as drag is concerned, plus you need a big prop
 to get out beyondthe
 diameter of the motor. There are units with 5-1 gear box
 ratios at 48V 1500Wbut they
 can weigh around 14kg. I bought an 1850W Hobby King BLDC
 outrunnermotor for
 $56- & it weighs 530 grams. So more powerful &
 1/27th the weight.This does
 236 rpm per volt, & from what I've read you
 don't want to be turning yourprop at
 more than 3000rpm on a sub. This means I would have to drive
 this motor with a maximum
 of 12V & it's rated for a maximum of
 37.To
 disipate the heat from the stationary inner coil of an
 outrunner, I may be forced togo with
 oil compensation; which is what most commercial brushless
 thrusters are anyway.One
 solution I can see is to go with a much larger hobby type
 motor & run it way belowit's
 maximum voltage to keep the revs down. Also I wouldn't
 be thrashing the motorwhich
 may help it live a lot longer.Need to
 do a lot more study here, then experimentation with motors
 & props in water.AlanP.S. Hank
 I was given a motorized Golf trundler & converted it to
 a trike with ape hangersand
 pink banana seat for my girls. Boy did they love showing off
 on that.
      
   From: hank pronk via
 Personal_Submersibles
 <personal_submersibles at psubs.org>
  To:
 personal_submersibles at psubs.org 
  Sent: Friday, October
 31, 2014 1:32 AM
  Subject:
 [PSUBS-MAILIST] Alan needs a motor
  
  
 Alan,
 I just went on ebay and
 found a 1,000 watt 48v brushless motor with controller for
 200 dollars.   It is for an electric bike.  I bought one
 for my son a few years back and it was amazing.  He was
 driving it all over town and towing his buddy on his skate
 board. Just type in  brushless 48 v motor.
 You won't need a gearbox either.
 Hank
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