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Old Aug 10, 2004, 10:44 AM
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Mad Max meets the Thinker
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Pittsburgh, PA
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Originally Posted by Viper Pilot
Ok, I've never tried multi-motor planes, and I'm not entirely sure of the setup.

Tell me if I have this right.

Speed 400s draw about 10 amps for good power. I want to use three 6 v. S400s. A singe motor seems to run fine with an 8.4 v. battery.

With 3 of these in series, the voltage needs to be about 24 volts, which would deliver 8 volts per motor.

Is the current draw on all three still 10 amps??

Please, someone, tell me if I have this right??

With a plane with AUW near 48 oz. work with a 20 x 1100 battery pack??

I'm not sure you want to do this, unless the motors loading is VERY equally matched parallel is MUCH better. Use a 7 Cell GP3300 with a high current ESC, using a BEC with it will work better because it has to drop a lot less voltage (that will save you weight).

Series is tricky because what WILL happen is if there is a slight imbalance in the loading of any of the motors (IE it runs a TINY bit slower because of the prop), the other motors will see a higher voltage and begin to spin a bit faster it's a rather interesting but anoying situation, especially with 3 motors. Your other option and just as good is use 14.4V (or if you can find them 18V) this will drop your amp draw per motor. One thing I have noticed is higher voltage motors tend to operate more efficiently so this might be a much better option as you can run it with 16 or 17 cells and get your current at about 12.5A not a big draw. And you loose some weight.

If you hae the motors already though... I would go with a higher current ESC and GP3300 battiers.

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