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Old Oct 05, 2012, 05:36 PM
Little-Acorn is offline
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San Diego, CA
Joined Dec 2006
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Originally Posted by Little-Acorn View Post
That's the number reported by Blaser for his plane. I hooked a WattMeter to my plane last night before swapping out the stock motor, and found it drawing 19.5A at 11.5V with a (non-stock) Turnigy 2200mAh 25C 3s battery and the stock (mis-formed) propeller. Volts times Amps =224 Watts. With an APC 9x4.5E propeller, it drew 23.2A, also at 11.5V, V*A=267W.

As always, Your Mileage May Vary.
I just put the original stock motor back in, and put an APC 9x4.5E prop on it since both my stock props turn out to be mis-formed (the blades are not 180 degrees apart! More like 178 or so). Also left the dual plug on the 60A ESC harness, so I'll be running the two 2s 5000 mAh R/C car batteries on it in series.

With that prop, it draws 27.5A at full throttle, and one battery fell to 6.7V. I'd guess the other is doing about the same, V*A=368.5 watts. It'll probably change somewhat in the air.

Rather unimpressive performance from the GensAce batteries. I don't recall abusing them THAT badly in the car. I'll check RPM too, now that the sun is up. Well, it's cloudy, hopefully the optical tach won't mind.

Might also try the 8x6 3-blade EMP prop just for kicks and grins, though it might be too much for this motor (ditto for the 9x4.5 2-blade). I'll probably pick up an APC 8x6E 2-blade if an LHS has one, they seem fairly well balanced.

ON EDIT: The other battery maintained 7.0V, guess it's a little healthier. RPM was 12,600 with the 2-blade APC 9x4.5E prop, voltage 13.7V, V*A=376.75 Watts. That's about the RPM the SuperTigre .23 turned without a muffler on my old TriSquire with the Heathkit radio (double-deck receiver, KPS-9 servos, plane weighed a ton). So that should keep the SSS out of the weeds adequately.

With the 3-blade EMP 8x6 prop, it drew 35A at 11,650 RPM. The ESC didn't get warm, though I only had it turning that fast for 5 seconds or so. Might keep that prop on the plane for the next flight. RPM with no load at that voltage is theoretically 17,125 RPM, so it's lugging down a little. Well, I've abused motors worse. Time to go fit those two batteries in the nose (some trimming needed) and see what it does to weight&balance.
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Last edited by Little-Acorn; Oct 05, 2012 at 06:02 PM.
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