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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Dennis Toth on February 12, 2021, 08:28:20 AM
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Guys,
I'm looking to save some weight and one area is the motor size. I have two choses a 2808 1100kV or a 2320 x 820kV. The 2808 is about 3/4oz lighter and would be preferred. I intend to use a 9x6 prop at 9950 rpm on a 4S pack. My question is does the can length have more impact on amps (and torque) then the diameter or vise-versa?
Best, DennisT
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What actually determine a motors torque rating is the area of the magnet gap, so length * diameter*pi.
But not the external dimensions, you need the internal ones of the core laminations.
This is sort of like the long stroke versus short stroke arguments about torque in IC engines. If you do the math all that really matters is displacement.
One dimension simply trades off with the other
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Saving weight with a lighter motor never yields a lighter setup because you will surely pay the price downline with bigger battery and bigger ESC.
If you really want to save weight use a bigger motor and use smaller ESC and battery.
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I decided to go with the BadAss 2320 820kV. I did a quick test run and it spins up smooth and hits the rpm. The BadAss motors are generally 15% lower battery draw then the cheap motors. I'm hoping it will let me drop down to a 5S 1350mah TP pack, this saves about 2oz. Test flight as soon as we get a claim day.
Best, DennisT
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Update: I flew the BadAsss 2320 820kV with the 10x6.5 APCE P, at 9950 rpm. This worked very well and had room to spare. Actually will need to de-pitch back to 6 ish as the lap time was 4.44sec on 60' c to c.
Best, DennisT
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Update: I flew the BadAsss 2320 820kV with the 10x6.5 APCE P, at 9950 rpm. This worked very well and had room to spare. Actually will need to de-pitch back to 6 ish as the lap time was 4.44sec on 60' c to c.
Best, DennisT
Remember with electric you can drop the RPMs a little to adjust lap time. Gives more head room for RPM control and should reduce battery usage.