Expert: Ken Myers - 10/9/2009

Question
Hi Ken,
I just finished building a CMP Transall C-160 EP (1450mm wing span); I put 2 x Ultrafly F18-10 motors with 2 x 30a escs and 2 x 4000 3s lipo. The props are 9,5 x 7,5.
I normally fly my airplanes with at least 100 watts per pound. The Transall weighs 6 pounds but I only have 550 watts at full throttle because of the restriction of prop size. I'm sure it is OK for take off, but one in the air, let's say at 2 throttle, what kind of flying do you think I will be able to achieve?
Thanks,
Philippe

Answer
Hi Philippe,

100 watts in per pound is kind of a standard target goal today, so 550 watts in on a 6 pound plane should not be a problem especially when flying a scale like plane in a scale like manner.  Back in the NiCad days we tried for 60 to 75 watts in per pound, and the planes flew well.  You have some large capacity packs, so your flights shouldn't be too short even though you may not be able to reduce the throttle as much as with larger props.  It should fly pretty well, would be my guess.

Enjoy your new plane,
Ken