Thread: Discussion Another coaxial F3P plane
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Old Mar 29, 2011, 02:53 PM
David Lundstrom is offline
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Sverige, Östergötlands Län, Linköping
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Kimmo thanks for explaining. I really like this idea and the potential it has. I wish I had more time for experiments. How did you do your slip rings? You should really patent this idea

Originally Posted by Kimmo Kaukoranta View Post
Actually I have first built several single prop geared systems before the geared coaxial due to those benefits. The latest one, which also Janne Lappi was using in Lithuania weights <11g and provides 210g static with 7.4V 3.4A 25W input power using a 10" prop. I do not think there is an direct drive motor which can match that. If anyone is interested on that I can write a bit more on that in a separate thread when I have the time.
I agree. To give you a comparison. I made a 14g motor wound for high torque. With a 10 inch prop I got 182g of thrust at 3,96A from a 2s batt. Efficiency in terms of gram/watt was decent, but motor efficiency is as low as 38%. Regular F3P motors of the same weight, turning GWS 8x4.3, usually are in the range of 40-50% and 250g thrust. We tend to over prop for the preferable flying characteristics a large prop offers, so theoretically geared motors in F3P should be beneficial. Please share your experience.
…Although I must say that I don’t fancy the “kyosho minimum” sound a geared motor produces. Could belt drive be an option?

Donatas (aka DaveL). Good luck at Etoc! A symmetric with contra prop must be as optimal as it can be.

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