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Basic Information for A New Electric Flyer


Old 11-23-2013, 11:10 AM
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Default Basic Information for A New Electric Flyer

I have been a glow flyer for over 30 years and due to noise abatement in my community I must switch to electric. I am also a scratch builder and am looking for a place where I can learn the basics of electric propulsion. Can anyone direct me to a place where I can get the following questions answered?
1. How do you determine what motor is required for a certain size plane? Is is based upon weight of the complete plane? What motor characteristics are considered when making the selection?
2. Once you determine the motor, how is the battery size determined? what determines the amount of MAH and cells?
3. Is it correct to assume that a 30A ESC is sufficient for a Lipo with a 30A power rating?
4. What determines the correct propeller size? Is there a table somewhere that this information can be gleaned?

As you can tell, I know nothing about electrics and need LOTS of help. I flew a Zagi about 10 or 12 years ago and that is the sum total of my experience with electic RC. If you want, you can respond direct to tkennedy63@msn.com.

Many thanks in advance.
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Old 11-23-2013, 08:50 PM
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If you look at the front page of the electric training forum, there is a sticky, all you wanted to know about electric. Has tons of good stuff.

Simple answer to 1, is trainer, 75 to 100 watts per pound, 150 to 200 lots more fun

No real "simple" answer to 2 through 4.. I ran some number for 46 electric motor.

If I set it up with a 12x6 prop, 3s 4000mah battery I get 190 watts and 41 ounces of thrust.. Not a whole lot of power. Just changing to a 4s battery I get 390 watts with 70 ounces of thrust. Going to a 5s battery I get 675 watts and
101 ounces of thrust. ^s battery gives me 1048 watts and 137 ounces of thrust. Just changing the number of cells in the battery can have a huge impact on the power of the motor. Now if I wanted to use a 3 cell battery I would have to use a very large prop. If I use the first battery, a 3s 4000mah battery and a 19X6 prop, I get 542 watts with 99 ounces of thrust.

Yes it can get really confusing to learn all of this. Best advice is to double check your setup on here and to get a watt meter so you have less chance to let the magic smoke out of your electric setup.


Here is a calc tool you can use. http://www.ecalc.ch/motorcalc.htm?ecalc&lang=en

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Old 12-07-2013, 08:39 PM
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