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Author Topic: Quick comparison.. brushed brushless for scale boats  (Read 1775 times)

johnredearth

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Quick comparison.. brushed brushless for scale boats
« 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/[/size][/size]



rnli12

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Re: Quick comparison.. brushed brushless for scale boats
« Reply #1 on: October 22, 2016, 09:38:03 PM »

John,


Really simplistic comparison thanks for the link, much appreciated.


Rich

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Regards,

Rich

Netleyned

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Re: Quick comparison.. brushed brushless for scale boats
« Reply #2 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
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inertia

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Re: Quick comparison.. brushed brushless for scale boats
« Reply #3 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
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g6swj

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Re: Quick comparison.. brushed brushless for scale boats
« Reply #4 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
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cos918

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Re: Quick comparison.. brushed brushless for scale boats
« Reply #5 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
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johnredearth

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Re: Quick comparison.. brushed brushless for scale boats
« Reply #6 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

cos918

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Re: Quick comparison.. brushed brushless for scale boats
« Reply #7 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
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