[PSUBS-MAILIST] Alan needs a motor

[Alan James via Personal_Submersibles]

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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