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Author Topic: Brushless motor impact  (Read 1287 times)

6705russell

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Brushless motor impact
« on: August 17, 2009, 09:59:14 PM »

I am currently fitting out a patrol boat with brushless motors, the boat weighs in around 8kg and measures 1500mm x 500mm, i am going to use two Tornado Thumper motors which have a power output of 1400w each, now compared to two MFA 850 type motors which have a power outputof 157w this is a huge step in power. My question is how do i know the propshafts are man enough for the job, will it just be trial and error or will they take this kind of power? I mhave bought two heavy duty M5 shafts from Mobile Marine Models in the hope that they will be ok....

Has anyone had any problems with shafts using brushless motors?

Many thanks

Russ
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nick_75au

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Re: Brushless motor impact
« Reply #1 on: August 18, 2009, 07:13:37 AM »

I havent got any brushless that big but I do have a 900 watt per shaft brushed setup, I use 6 mm (1/4 ish) 316 stainless steel rod.  Strong enough to rip the blades off a 70 mm brass prop with no shaft issues. My boat is about the same size weighs about 12 Kgs
Nick
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6705russell

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Re: Brushless motor impact
« Reply #2 on: August 18, 2009, 07:35:45 AM »

Thanks Nick,

What motors are you using in your boat, i have this thing about brushless motors that some of them dont look physically big enough for the job but the power rating says they are more than adequate....

Russ
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nick_75au

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Re: Brushless motor impact
« Reply #3 on: August 18, 2009, 08:17:17 AM »



2 Darke Horse 4:1 planetary gearboxes mated to a 2:1 belt drive, 45 amps at 24 volts each pair.This set up does power the boat very well, proving a point that brush-less is not necessarily the be all and end all.

Photo not the best the boat is still a work in progress.

 I agree with you my brushless Springer has a 20 mm diameter motor driving a 40 mm prop with more thrust and less current than a direct drive 550 motor.

Nick



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