[PSUBS-MAILIST] thrusters

[Alan via Personal_Submersibles]

Hank,
additionally you have to replace the propeller shaft with stainless.
It is a press fit into the bell ( outer spinning part) you also need to 
cut a few circlip grooves.
Should mention that there are inrunner & outrunner brushless motors.
You are wanting the outrunner as they have a lower rpm for a given
size & more torque. There is an important term "kv" which is no load revs
per volt applied. You can have the same size motor with the option of
several different kv's due to the motor windings. You want the lowest
kv if you are going direct drive. Mine are 6374 motors (63 diameter 74 length)
with a 60kv rating.  I had mine especially wound but you can now buy them
off the shelf. 
There are some pretty cheap rovs that would save you a lot of time
& learning, however these little motors are amazing & worth playing with.
Alan

Sent from my iPad

> On 14/11/2017, at 6:30 AM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Hank,
> didn't click that this was for your rov project.
> The brushless motors are a 3 phase motor & need a brushless motor
> controller. I am not sure how far you can run the controller from the motor.
> You would have to have the controller on the rov & signal wires in the sub..
> The motors & controllers are quite cheap through Hobby King or China.
> There are mounts that normally come with the motors.
> You could buy a 36V option. Hobby motors are classed in S's,  1S is 3.7V
> so 10S is 37V.
> They come in two flavours, sensored & uncensored. Sensored have rough
> start up & low speed characteristics under load. However if you go with
> sensored then you have to coat the sensor board, & I'm not sure how the
> sensors will perform with a coating on them.
> The company blue robotics has the whole thruster minus the speed controller
> for $169-
> https://www.bluerobotics..com/store/thrusters/t200-thruster/
> Well worth the price for the time you'll save.
> Cheers Alan
> 
> Sent from my iPad
> 
>> On 14/11/2017, at 2:10 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> 
>> Alan,
>> Yes they are low powered, but that works for me because I am not dragging a 300 foot tether.  My tether will be 50 feet.  Do the brushless motors need a special controller?  or will a PWM controller work?  We tend to design and build things to last for an unrealistic life span.  You mentioned a while back about water bearings lasting only 2,000 hrs.  I doubt any Psub will see 2,000 hrs in its entire life time.  If an 119 dollar ROV motor lasts 100 hr, I would get several years out of it.  I am very realistic about spending versus life expectancy.
>> Hank
>> 
>> On Monday, November 13, 2017, 5:08:40 AM MST, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> 
>> 
>> Hank,
>> yes there is a lot of DIY in some of those groups.
>> I did run a motor without a housing & things like the magnets got rusty.
>> I don't think they would stand up to sea water & any mucky water. As
>> the motors would have any thin layers of expoxy / glue sand blasted off.
>> From memory the motors were reasonably low powered.
>> Alan
>> 
>> 
>> Sent from my iPad
>> 
>>> On 14/11/2017, at 12:44 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>> Alan,
>>> I joined an ROV group and have found some pretty interesting thruster stuff.  I think you have done the same?  You can buy thrusters that are brushless and built to run in the water with no sealing.  Sounds like they just epoxy the armature and replace the bushings with plastic. 
>>> Hank
>>> _______________________________________________
>>> Personal_Submersibles mailing list
>>> Personal_Submersibles at psubs.org
>>> http://www..psubs.org/mailman/listinfo.cgi/personal_submersibles
>> 
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