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Old Sep 06, 2014, 02:50 PM
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Joined Aug 2013
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Discussion
most efficient brushed rc boat motor

Hi guys
what type of brushed motor is the most efficient?
Im trying to get the longest run time on a scale boat
Using a nihm battery

the longest run I can think of is like the set up on my bristol bay
2 hours with a 5000nihm battery?

Please dont say brushless

thanx
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Old Sep 06, 2014, 03:12 PM
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Acetronics's Avatar
Le Treport, France
Joined Jun 2004
1,403 Posts
simple ...

you just have a look to the efficiency curves for your motor, and try to run it as close as possible to the best values ( ... )
that mean choosing carefully your propeller(s) pitch and diameter ... and even use variable pitch ones !!!

Brushless or not: same tweaking !!!

Alain
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Old Sep 07, 2014, 07:28 PM
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Joined Nov 2007
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As Acetronics said, you have to run at the peak of the efficiency curve. Here is a typical spec sheet:

http://www.jameco.com/Jameco/Products/ProdDS/232022.pdf

Note that the efficiency curve has a narrow peak and you have to hit the best RPM very close. Brushless motors also have a narrow peak.
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Old Sep 08, 2014, 04:47 PM
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Hastings, New Zealand
Joined Jan 2001
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Don't over-power the model. Use a small motor with gearbox (3~4:1 ratio) and run the largest prop you can. The prop should have low pitch and large blade area to maximize thrust. Use an ESC with high rate PWM (3KHz+). Make sure that your running gear operates smoothly (couplers lined up, bearings well greased etc.).

People often use a large, low Kv (high voltage) motor direct drive, but this is an inefficient setup because at low speed the motor wastes a lot of power just turning itself over, and at high speed the motor's high armature resistance also wastes power.

Here's a freighter that I set up for a friend. He put three 12V 7Ah SLA batteries in it just for ballast, but it runs for hours on a single 6V 3Ah battery. The power system is a Speed 280 6V geared 4:1, driving a 50mm 4 blade brass prop. It achieves scale speed at 1/2 throttle.
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Old Sep 12, 2014, 02:39 AM
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Thanx guys for replying

Bruce do you think maybe you could help me on a good motor set up for this historic boat






thanx
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Old Sep 12, 2014, 02:40 AM
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43 inchess in length
And 5 inches wide
For the hull
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