[PSUBS-MAILIST] Brushless thruster test

Sat Jan 30 16:55:32 EST 2016

Alan your thruster is coming along.  What is the pitch of the prop that you
are going to use?  It is a little hard to tell the size of the unit from
the pictures.  What is the prop diameter and what is motor diameter?

I am working with some engineering students on a new variable pitch prop
for my boat.  They have also built a test rig to measure the bollard
thrust, rpm, current and voltage of the thruster.  Hopefully in a week or
so we will get some testing done a a MK-33 prop that goes with the MK-101
lower unit.

How did you measure the thrust on your thruster?  How did you calibrate the
test rig?  What kind of duty cycle is this motor rated for?  What do think
the final HP will be for your thruster?

Thanks for sharing your work to date on the thruster.

Cliff

On Sat, Jan 30, 2016 at 12:43 PM, Alan James via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Hank, Tim.
> With a load on it should be about 1300 rpm.
> It was leaking just sitting in the pool. When I got home
> I poured a low viscosity oil in the wire entry & it just flowed
> out the seal.
> It is quite a learning experience. There are some big gaps in my
> understanding
> of the maths of what is going on.
> I am getting a 1500W sensored motor with low kv & an operational voltage
> of 44V
> made up for me. The motors I have are sensorless & it is hard to find a
> good
> speed controller with reverse for sensorless motors.
> Alan
>
>
>
> ------------------------------
> *From:* hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org>
> *To:* Personal Submersibles General Discussion <
> personal_submersibles at psubs.org>
> *Sent:* Sunday, January 31, 2016 7:08 AM
> *Subject:* Re: [PSUBS-MAILIST] Brushless thruster test
>
> Alan,
> That motor looks pretty nice!  I still think rpm is your enemy, seal wise.
> Hank
>
>
> On Saturday, January 30, 2016 9:20 AM, T Novak via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>
> 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 housing
> or 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 through
> where it comes out of the housing.
> Cheers Alan
>
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