[PSUBS-MAILIST] Brushless Thrusters
Alan via Personal_Submersibles
personal_submersibles at psubs.org
Tue Sep 9 02:48:45 EDT 2014
Hank,
all the big boys are using them.
They are more efficient, & power to size ratio is high. That one I posted a link to
is 1&1/2" diameter x 3" long & 1200W, & $30-. There would be a lot less motor
to get in the way of the kort nozzle intake.
As to motor cooling. From what I have read it is a big issue & overheating causes most motor failures. Motors like Minnkota & probably your motor are purpose built with thicker windings designed to handle the extra heat building up inside an enclosed unit.
If I am home building & picking a brushed motor off the shelf I might be hard pressed to find
one suitable & probably wouldn't recognize it anyway. I could always oil compensate
as a means of cooling. However the in- runner brushless have (as said previously) the
coils on the outside, so heat generated is conducted straight through the can to the
water rather than through air first as in an out-runner brushless or brushed DC motor.
Motors are rated on efficiency, & if you have an 80 % efficiency on a 1000W motor
you have a 200W heater inside your thruster can.
I am pretty sure the professionally made brushless thrusters would be made by sourcing
existing motors, motor controllers, planetary gear boxes & shaft seals, & making a can to fit them in.
It's just a matter of tracking these items down. ( which is a pain)
Regards Alan
Sent from my iPad
> On 9/09/2014, at 11:56 am, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Alan,
> I am wondering why your so interested in brushless motors. What am I missing, also there has been discussions about heat, what heat? A motor in water, what could be better :-) After a 3km run in gamma, my motor is maybe Luke warm at best.
> Hank --------------------------------------------
> On Tue, 9/9/14, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
> Subject: Re: [PSUBS-MAILIST] Brushless Thrusters
> To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
> Received: Tuesday, September 9, 2014, 12:35 AM
>
> Update,Am still Googling away
> in pursuit of a home made brushless thruster.I am set on using an in-runner motor as they have
> the coils on the outside & will be ableto transfer heat through the can.The problem with in-runners is they have higher
> revs than out-runners, however either will require a planetary gearbox. I am looking at
> reducing the revs down to below 3000 rpm. This is based on other brushless thrusters I have
> looked at but might not be right ( any
> recommendations)?Another problem is that
> most seem to draw huge amps.Here is a
> 1200W motor for $30-. Of course there is the price of the
> controller & planetary gear that are
> needed.http://www.hobbyking.co.uk/mobile/viewproduct.asp?idproduct=17720&type=&idparentcat=364Most of the suitable motors seem to be found at
> places like Hobby King, and are used on RC trucks, or found
> on E bike sights. The aircraft motors aren't as
> robust.These motors are tiny, but
> hugely powerful, so there is the potential to make a small
> streamlinedpowerful unit.I haven't had much luck with a matching
> gearbox. Some of the planetary gearboxes recommendoiling (no good to me unless I oil compensate)
> while others don't. I am looking for a cylindrical unit
> to match my motor, preferably with thrust
> bearings.If anyones got any advice or
> experience in this realm I'd be pleased to hear
> it.Regards Alan
>
> Sent from
> my iPad
> On
> 7/09/2014, at 8:43 pm, Alan via Personal_Submersibles <personal_submersibles at psubs.org>
> wrote:
>
> Hi Hank,the kort
> nozzle on the Indonesian thruster looks a bit
> Naff. ( I am designing an art work
> here.)I could get a price for the unit without
> kort nozzle, butI'm wondering if I could
> build something for 1/2 that price.There are some
> reasonably priced brushless motors about.I
> don't know that I could just retro fit a thrust bearing
> inside the can of the motor.I tried to put a
> thrust bearing for reverse inside my brushed thrusters,
> butcouldn't find one with a thin enough
> section to fit.Also the motors are a bit
> expensive to just buy & hope you can fit
> one.How did you fit the thrust bearing on Gamma?
> Did the propellor shaft extend out the backof
> the motor?Alan
>
> Sent from my iPad
> On
> 7/09/2014, at 7:22 pm, hank pronk via Personal_Submersibles
> <personal_submersibles at psubs.org>
> wrote:
>
> Allan
> Dont worry about
> thrust bearings to much. They are aesy to get, I bought one
> for Gamma , real heavy duty for 80 dollars. Personally I
> would just use a good quality bearing and replace it once a
> year for 8 bucks, if it is a small thruster. Are you not
> happy with the Indonesia thrusters? Or to pricey?
> Hank
>
>
>
>
>
>
>
>
> From:
>
> Alan via Personal_Submersibles
> <personal_submersibles at psubs.org>;
>
>
>
> To:
>
> Personal Submersibles General
> Discussion <personal_submersibles at psubs.org>;
>
>
>
>
> Subject:
>
> [PSUBS-MAILIST] Brushless
> Thrusters
>
>
> Sent:
>
> Sun, Sep 7, 2014 11:58:56 AM
>
>
>
>
>
> Hi people,
> I've
> spent several hours today looking at brushless thrusters
> & wonder if anyone else has looked at them or got any
> ideas. There is the Indonesian thruster I posted a few weeks
> back at US 2,200. There is also the Haswing Protruar 2hp
> that Emile has; however they state that it's for fresh
> water only, & I think Emile said it was a bit noisy.
> The inrunner motors that have the winding on
> the outside, seem a good option as they cool through
> convection to the can. They also need higher revs for torque
> & require a planetary gear box or similar. ( which a lot
> have built in)
> I was looking at the
> option of making my own thruster, however the motor would
> require a thrust bearing & I don't
> know of any that would have one other than
> maybe a high powered battery operated drill.
> Any thoughts, suggestions thanks.
> Alan
>
> Sent from
> my
> iPad
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