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Jan 26, 2009, 08:20 PM
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the war on propellers

So threw down $6 for all the 12" propellers sold locally to show U how inefficient they were. The theory was to put 1 propeller on 1 motor & compare the PWM with the other motors. If the PWM was lower, the propeller was more efficient & the flight should last longer.

That didn't work. For all the 12" propellers, the PWM was much lower but the battery died instantly. What happened? Lower PWM should mean lower wattage, but lower PWM sucked more power.

The theory is at low RPM with high load, the same coils stayed on a lot longer than they did at higher RPM with low load. The less frequently the coils switch, the more time they spend in the peak of the sine wave. Normally the same coils R only on very briefly & spend most of their time in the rising & falling edges of the sine wave. The gain in power from less frequent switching was more than the loss of power due to lower PWM.
Last edited by Jack Crossfire; Jan 26, 2009 at 08:27 PM.
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