Model Boat Mayhem

Technical, Techniques, Hints, and Tips => BRUSHLESS Motors and Speed Controllers => Topic started by: johnredearth on October 22, 2016, 09:06:43 pm

Title: Quick comparison.. brushed brushless for scale boats
Post by: johnredearth on October 22, 2016, 09:06:43 pm

Hi


You guys all know about this but I had to find out for myself!


[size=78%]http://www.scratchbuildwithjohn.com/public/brushless-verses-brushed-verdict/ (http://www.scratchbuildwithjohn.com/public/brushless-verses-brushed-verdict/)[/size][/size]

Title: Re: Quick comparison.. brushed brushless for scale boats
Post by: rnli12 on October 22, 2016, 09:38:03 pm

John,


Really simplistic comparison thanks for the link, much appreciated.


Rich

Title: Re: Quick comparison.. brushed brushless for scale boats
Post by: Netleyned on October 23, 2016, 10:58:18 am

Certainly makes me rethink the power train for any future displacement models.


Nice trawler by the way  :-))


Ned

Title: Re: Quick comparison.. brushed brushless for scale boats
Post by: inertia on October 23, 2016, 02:10:18 pm

That's quite fascinating, John - many thanks for taking the trouble to do the experiment and document it so clearly. Interesting to note the very low current drawn c/w a brushed motor. I'm sure that many modellers still think that fitting a brushless motor will necessarily treble the speed of the model and increase the current tenfold. Now they know it just ain't so.  :-))
DM

Title: Re: Quick comparison.. brushed brushless for scale boats
Post by: g6swj on October 24, 2016, 07:57:15 pm

John,

Great video - interesting experiment. 

Love the way you found a substitute part for the motor shaft!

Regards
Jonathan

Title: Re: Quick comparison.. brushed brushless for scale boats
Post by: cos918 on November 21, 2016, 10:01:53 pm

Hi John
very nice vid . I found it very useful . Couple of questions . what prop size do you have on your boat.What made you go for a reduction belt instead of direct drive .


John

Title: Re: Quick comparison.. brushed brushless for scale boats
Post by: johnredearth on November 21, 2016, 11:37:46 pm

Hi


The prop size is about 45 ml.  It is also home made.  With a 545 I have generally used the rule of thumb that any prop over 30-35 is better with a reduction.  As noted in the video this really helps with slow rotation, and I prefer belt drives.  I could just use o ring belts but the timing belt is more efficient as there is less requirement of lateral tension. 


As my props are home made I could also decrease the angle of the blades, but I have never actually tried that.  I have tweaked the blades often though. 


Hope that helps


John

Title: Re: Quick comparison.. brushed brushless for scale boats
Post by: cos918 on November 25, 2016, 10:10:04 pm

Hi John
thanks for the rely. I am looking for a low KV out runner to get low rpm s .I see yours is 1400kv runing on a 2s lipo. gives you about 11760 rpm then your belt  drive drops it 1:3.5 to about 3360 rpm which is a very nice.
The problem I am finding is the low KV out runners need 4s and above . I am running a 3s lipo  . Your belt idea has given some new ideas .


thanks
john