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Old Dec 08, 2006, 06:02 AM
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Scotland
Joined May 2006
106 Posts
Help!
Multiplex Pico Cub motor/prop choice

I'm thinking of getting a Multiplex Pico Cub (its end of line at my local modelshop). I see it comes with a direct drive speed 400 brushed motor. As I have no spare rc gear at the moment Iíll be buying all new equipment for it. Looking on ebay I see I can buy a brushless motor/speed controller combo like the link below for about the same price as a brushed speed controller.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...5263&rd=1&rd=1

As brushless motors are more efficient than brushed and I want to use lipos to power it I would like to go down this route, also from reading the reviews, the direct drive seems pretty poor. However as I am relatively new to the hobby I have no idea what size of motor I should go for. Iím really looking for long gentle flights, but with the ability to handle a bit of wind and possible carry a small digital camera (I have a Sapac Extra for aeros!)

I would really appreciate any suggestions as to what size of motor/speed controller/prop and battery I should go for. If anyone has any cheap links on ebay this would also be appreciated!

Thanks
Stuart
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Old Dec 08, 2006, 03:50 PM
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Scotland
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anyone?
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Old Dec 08, 2006, 03:56 PM
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Livermore, CA
Joined Sep 2004
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Not knowing everything about brushless motors, this motor seems to be a higher KV motor, spinning a smaller prop. The Mulitplex Cub is almost 20 ozs and the manual sugests a geardrive 400 for slow flight. I would think a lower KV motor, able to put out 15-20ozs of thrust on a 2 cell lipo, swing a 9-10" prop, would be better.
Maybe some else here has got some ideas! Butch
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Old Dec 08, 2006, 06:07 PM
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Scotland
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Thanks that makes a good starting point.
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Old Dec 08, 2006, 10:43 PM
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United States, MN, Big Lake
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crazyhaggis:

If you do go with a brushless and Li-Po combo, it will be difficult to keep the Cub from coming out tail heavy. I fly mine with the SP400 through a 3.09:1 gear reduction and 7-cell 1100 Mah Nimh's. It swings a 10x6 GWS HD prop drawing about 10 amps static. You want to have about 100 watts of motor input power to make it a versatile flyer. Although slow gentle flight only takes about 30-40 watts of power.

If you go direct drive brushless you want a 100 watt motor capable of giving about 30-35 mph pitch speed on the prop. Various combinations of 1000 to 1500 KV motors with 2 or 3 cell Li-Po's can get the RPM on a 9x5 or 10x6 prop that will work. I think the Multiplex Cubs that I have seen with Li-Po power have had creative re-location of the battery to keep them from being tail heavy.
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Old Dec 10, 2006, 11:03 AM
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Scotland
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Quote:
Originally Posted by Aerospacer
crazyhaggis:

If you do go with a brushless and Li-Po combo, it will be difficult to keep the Cub from coming out tail heavy. I fly mine with the SP400 through a 3.09:1 gear reduction and 7-cell 1100 Mah Nimh's. It swings a 10x6 GWS HD prop drawing about 10 amps static. You want to have about 100 watts of motor input power to make it a versatile flyer. Although slow gentle flight only takes about 30-40 watts of power.

If you go direct drive brushless you want a 100 watt motor capable of giving about 30-35 mph pitch speed on the prop. Various combinations of 1000 to 1500 KV motors with 2 or 3 cell Li-Po's can get the RPM on a 9x5 or 10x6 prop that will work. I think the Multiplex Cubs that I have seen with Li-Po power have had creative re-location of the battery to keep them from being tail heavy.
I take it the problem arises from the lipo being far lighter than the nimh pack?
Thanks
Stuart
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