So much to learn, so little time.
09-02-2007, 09:14 AM
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So much to learn, so little time.
One of the reasons I'm hooked on electric aircraft is that there is so much to learn. For example, for some particular motors, one may use either 3-in-series or 4-in-series battery packages. With the 3-series battery package, one uses a larger diameter prop with greater pitch as opposed to the same motor powered by a 4-series battery package. Why? thx Jim
09-02-2007, 12:22 PM
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RE: So much to learn, so little time.
The 3s pack has a manuf. spec of 11.1volts, the 4s pack has a manuf. spec. of 14.8 volts. Everything in electric power is based on total watts produced. Total watts produced is calculated by multiplying the amp draw of the prop./motor combo x the voltage supplied by the battery. Thus the 4s pack is going to provide a big increase in total watts over the 3s pack under the same settings. It is also going to create more RPM's and power at equal amp draws. If you ran the same prop. on the 4s pack that you ran on the 3s pack you would risk over taxing the motors max. watt output number. Thus a smaller prop. must be used to compensate. Hopefully that makes some sense 
Example of watt calculations:
Say you have a system that is pulling 30amps at WOT.
3s pack = 30 amps x 11.1volts = 333 total watts
4s pack = 30 amps x 14.8volts = 444 total watts
Example of watt calculations:
Say you have a system that is pulling 30amps at WOT.
3s pack = 30 amps x 11.1volts = 333 total watts
4s pack = 30 amps x 14.8volts = 444 total watts
