[PSUBS-MAILIST] Brushless thruster test

[Alan James via Personal_Submersibles]

Thanks Glen,there are a lot of direct drive brushless thrusters out there that are made forsubs, ROVs & DPVs. I have performance specs on a number of themthat I can compare with my results. So just a matter of finding the rightmotor & prop combination.I am now looking at sensored BLDC motors rather than the sensorless motors I have been using. This is because it is difficult to find speed controllerswith reverse for the sensorless. The sensored motors are used in tractionvehicles where they want a smoother start, whereas sensorless motorstend to be in things like RC planes that don't need reverse.Cheers Alan
 

      From: gbrown091 via Personal_Submersibles <personal_submersibles at psubs.org>
 To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
 Sent: Monday, February 1, 2016 9:05 AM
 Subject: Re: [PSUBS-MAILIST] Brushless thruster test
   
Thanks Alan appreciate your input on the thruster testing. RegardsGlen

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-------- Original message --------
From: T Novak via Personal_Submersibles 
Date:30/01/2016 18:20 (GMT+02:00) 
To: 'Personal Submersibles General Discussion' 
Subject: Re: [PSUBS-MAILIST] Brushless thruster test 

Thanks for the update, Alan.It looks like your research is coming along quite well.Tim  From: Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org] On Behalf Of Alan James via Personal_Submersibles
Sent: Saturday, January 30, 2016 1:47 AM
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Subject: [PSUBS-MAILIST] Brushless thruster test  I had an initial pool test of my brushless thruster yesterday.Thruster is on projects page http://www.psubs.org/projects/1235435392/brushlessthruster/A bit of a mixed bag. Firstly I was testing it on 36-37 V & not 44 that it was designed for,due to size restrictions on import of Lithium polymer batteries. I will buy the additional voltage.   I was getting 5kg (11lb) thrust off 150W & 10kg (22lb) off 515W, which is comparable &better than some commercial direct drive BLDC thrusters that I have specs on.However I got to 13kg thrust & the propeller seemed to slip at that point & even though it was running at 2,200W I wasn't getting any more thrust. I was only a couple of feet out from the pool edge when testing, so that could be contributing.Another factor could have been that the seal leaked badly & the motor was short circuiting through the water. Why did the seal leak? Possibly I damaged it hammering it in to it's housingor because I didn't polish up the propeller shaft. I have other motors I will be testing, so a lot more work & learning to do on this one.I did notice I had the same problem as  Cliff, with the motor wiring starting to wear throughwhere it comes out of the housing.Cheers Alan
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