Mess Deck: General Section > Tugs and Towing

Al khubar

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Darren007:
I have just bought the above tug, the builder fitted brushless motors- hobbyking


Is a brushless set up ideal in a tug?


I’ve not tested on water yet but I’m pretty sure it will be to fast?

JimG:
It all depends on the type of motor and the Kv rating of the motor. The Kv rating gives the number of revolutions per volt when off load.If they have used low Kv rated motors then they will be low revving and high torque which is what you want to drive a large prop on a scale tug. As long as you keep the battery voltage down then the speed shouldn't be too fast. If necessary then if you are using a modern transmitter you can set the throttle endpoint to less than 100% and reduce the speed like this.If they have fitted a high Kv motor then you might have a problem, these are high revving and suit small props better, using a large prop leads to overloading the motor and high currents. In this case a low battery voltage may be essential to keep down the speed and current.I have the ST Cruiser tug which has a low Kv rated brushless driving quite a large prop. I did find it overpowered as standard using a 3S LiPo pack but used the programming ability of the esc to reduce the maximum revs of the motor making it much more scale like.
Jim

Darren007:
Thanks for your reply! I’m not familiar with brushless. The motors have 2213-935kv on them?
Is this a ideal motor?

cos918:

--- Quote from: Darren007 on May 30, 2022, 07:09:16 pm ---Thanks for your reply! I’m not familiar with brushless. The motors have 2213-935kv on them?
Is this a ideal motor?

--- End quote ---


Depends on what size battery you use . So a 2s lipo is 7.4v and a 3s lipo is 11.1v ,Sealed lead acid SLA are 6v or 12v
So the battery voltage and times it by the KV. So a 2s lipo 11.1X935Kv = 10378 rpm. a 2s Lipo 7.4X935Kv=6919 rpm.
6V SLAx935Kv= 5610 rpm.
Some motors will only run a minium voltage. So if its a 3s min it wont like a 2s or 6vsla. My self I think they are a to high KV for a tug.
Give it a go before you buy any think eles.
John

Martin (Admin):

Yes, good advice from JimG & cos918.  :-))

Kv does sound a bit high for a tug... but you could use a belt drive reduction if needs be.
As you have the motor, it's worth connecting it all up to get a feel for it  / get a sense of the power, especially with your chosen propeller.

NB. Don't be too worried about dunking the whole motor in water, they are pretty robust, make sure you blow / air dry it afterwards!

This one:  https://www.unmannedtechshop.co.uk/product/brushless-motor-emax-mt2213-935kv/#

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