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Old Jul 13, 2016, 03:43 AM
remitt is offline
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Canada, AB, Edmonton
Joined Jun 2016
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Question
electric conversion

Hi all. I'm building a Cub Canard and would like to lose the ic in favour of electric. It has a wing span of 32" and will weigh around 6 oz before electrics. This is my first foray into electric gear and know very little about it. What's the best setup for this project? Motor, esc, timer, prop all that cool stuff. Is it easy to setup a pusher as an electric. If I reverse the motor rotation is it easy to fit the prop? .....
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Old Jul 13, 2016, 01:51 PM
BMatthews is online now
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The 'Wack, BC, Canada
Joined Oct 2002
14,348 Posts
You won't need much. For sport free flight with electric power you only need something like 20 or 25 watts per lb of final ready to fly model. So one of the small and light 10 to 13gram motors which can handle up to around 15 to 20 watts for a maximum rating will be more than enough. So assuming your model comes out at around 10 oz final weight you only need about 12 to 15 watts of power. From a single Lipo cell that puts out roughly 4 volts that means you will only be drawing from 3 to 3.5 amps from the cell.

Ideally you would run it from a single Lipo cell to both keep the weight down but also to allow you to turn a little larger prop. Those small motors have a very high Kv value. Kv being the natural RPM per volt they want to run at in the unloaded condition. Normally on 2 cells (2S for 2 in Series) they use a little 3 to 4 inch prop. By running it at a lower voltage you can use a more free flight friendly 5 or 6 inch prop.

You'll need to ensure you find an ESC that will run on 1 cell (1S). They are out there but not as common as the 2S and 3S capable ESC's.

Then you need a timer to drive the ESC. This is a specialty item which you'll need to send away for from one of the few makers of them. I've never had the interest so I can't say where to find them. Someone will be along shortly to tell you about them.

The funny thing about these electrics is that you control the power by the size of the prop. You can keep putting on larger and higher pitch props until the motor draws so much power that it'll burn out. So start out with a smaller size and try a flight. If it power glides to the ground then try the next size up. Keep going until you have a nice steady uphill glide sort of climb. For sport flying you don't need or want a rocket like climb. So sneak up on the size of prop that provides a nice positive climb without being too steep.

With brushless motors changing the rotation direction is as simple as swapping any two leads out of the three. After that just mount the prop with the curved side of the blades facing the nose.
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Old Jul 14, 2016, 02:47 AM
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GH crash - I practice a lot
United States, OK, Bartlesville
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Quote:
Originally Posted by BMatthews View Post
.

You'll need to ensure you find an ESC that will run on 1 cell (1S). They are out there but not as common as the 2S and 3S capable ESC's.

Then you need a timer to drive the ESC. This is a specialty item which you'll need to send away for from one of the few makers of them.
Micro Flyer Radio has some timer/speed controllers that would work well for your project
http://microflierradio.com/Timers.html
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Old Jul 19, 2016, 10:56 PM
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Thanks guys, that's a big help. I obviously have a lot to learn about it. I've found a few places that supply the parts and pieces and they are quite helpful. I still don't understand all the jargon or how to figure out what size fits what. Oh well....there's always google.

Martin
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