Yet another Prop Size Question
Greetings to all...
I'm just getting back into RC after a somewhat lengthy absence. Though I have been at this hobby off and on for over 40 years, I know from nuthin' about electric power. I decided a worthwhile first project would be to electrify an old "Easy Breezy" 2m sailplane, which I previously flew with a Black Widow .049 on a pod.
To this point, I've installed a Park 450 outrunner, Eflight 20A ESC, 1300mAH 3S 20C Lipo. I anticipate short motor runs in keeping with normal sailplane tactics, maybe 30 to 60 seconds. Airplane balances nicely, looks ready. But....
The guy at the store talked me into a 9 X 7.5 folding prop (I insisted on a folder, because they're cooler on sailplanes) and that was the only one he had in the store. The datasheet for the Park 450 motor calls for "9x6 to 11x3.8 Slow Flyer or 10x5 to 12x6 Electric" props.
Pertinent data for the Park 450 motor: rated 14A continuous, 18A surge for 15 seconds.
Now for the question: I just measured the static current draw at 15.5A using the 9x7.5 prop, at full throttle. So... Is this setup dangerously overpropped? Will the current draw increase or decrease when the prop unloads in flight? Should I change the prop before I burn up my glider, or should I be OK with limited motor runs?
Inquiring minds want to know.
Last edited by W7APD Alan; 01-22-2014 at 01:22 PM.