One more thing. The stock motor system turns the APC 12x7E prop at ~9600 rpm.

This calculates to about 580 watts output, which gives right about 83% efficiency (the rest goes to mechanical losses and heat - my 8 year-old wondered what happened to the other 17%). This is pretty good considering the output.

The static thrust calculates to about 6#. I will put a scale on it to verify, but this is a great number. The plane with my BIG batteries (4S 3700 mAh LiPo) is 57 oz rtf = 3.56 lbs, with 700 watts input gives 196 watts/lb (input). Needless to say this gives fast vertical climbs to well beyond the limits of sight.

Typically 100 watts/lb is enough for strong climbs, so we have nearly TWICE that amount!

Note I do not recommend running at full wide-open throttle for more than 10-15 seconds as it starts to get hot after that. The motor seems to hold up well under slightly lower power settings, reserving full power for vertical climbs.

This plane is a very strong IMAC practice plane! I do all my flying at a local field that is about 200x250 yards and the plane will easily stay in that space. It truly flies like a much larger plane.