Model Boat Mayhem

Technical, Techniques, Hints, and Tips => BRUSHLESS Motors and Speed Controllers => Topic started by: raflaunches on April 04, 2019, 02:43:22 pm

Title: Brushless assistance for new project
Post by: raflaunches on April 04, 2019, 02:43:22 pm

Hi everyone


I’m delving into the darkness (or is it enlightenment!) of brushless motors properly for the first time.
I’ve read the basics on this topic on the Mayhem from 2008 to get an idea of how it all works and just wanted to see if I’d got the right motors for the next project.


I’m building a 120ft patrol boat in 1/35 scale which measures out at 41 inches long and has twin engines/props and capable of between 17 and 21 knots depending on weather. It’s a deep hull vessel similar to the Bird class (Kingerfisher) used by the Royal Navy in 1970s to 1980s. It’ll need some ballast to get her down to the waterline (probably something in weight region of a 12v 10amp/hr sealed lead acid battery) so it’s relatively heavy too.


So I’m thinking something in the region of this brushless motor from Component Shop:


[size=0px]LC2835-9T 900KV Outrunner Brushless Motor Leopard Hobby
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  https://www.componentshop.co.uk/lc2835-9t-900kv-outrunner-brushless-motor-leopard-hobby.html (https://www.componentshop.co.uk/lc2835-9t-900kv-outrunner-brushless-motor-leopard-hobby.html)
  
  
  Two motors are needed and from my understanding since this model isn’t a fast planing hull like a MTB or ARSL and not as slow as a tug but somewhere in between I chose the kV accordingly but if someone knows better I’d appreciate some advice on the motors.
  Thanks.

Title: Re: Brushless assistance for new project
Post by: DaveM on April 04, 2019, 04:14:37 pm

What size and number-of-blades props are you intending to use, Nick?
DaveM

Title: Re: Brushless assistance for new project
Post by: raflaunches on April 04, 2019, 04:53:03 pm

Hi Dave


I’m going to go for a scale prop of something like a 25-30mm diameter 3-bladed propeller.
Obviously the prop diameter is open to change to get the best out of the motors for this task but if it stays around the 30mm diameter it would be in keeping with the scale.

Title: Re: Brushless assistance for new project
Post by: DaveM on April 04, 2019, 07:35:02 pm

Then I reckon the motors suggested would be fine on 3-blade x 30mm props and 2S LiPo's (or 6 cell NiMH). There's scope to increase the prop diameter a little and/or voltage without drastic changes to the performance. 30A ESC's would do the job nicely. Not a pretty boat though!
DaveM

Title: Re: Brushless assistance for new project
Post by: raflaunches on April 04, 2019, 07:40:20 pm

Thanks Dave for the confirmation and recommendations  :-))


And I agree, she won’t be a truly pretty model being very functional for the era, whilst not exactly like the Bird class she is very closely related and shares her sisters looks!