Yeah, and if I shave my legs, I could be a Sports Illustrated model.

Where you go wrong is by taking the power of the engine at 16k rpm. At what point of the takeoff run do you think it will be turning 16k?? Does OS supply a power/torque curve for the engine? If so, take the power developed statically -around 10k and the power developed around maybe ~12k rpm and you will get a better average power value for the takeoff run. The 12k figure is an estimate of the speed of the engine as the prop unloads when the plane gets some speed up. You could prop for max power, but then the prop efficiency would sink under the grass, as it would take a small diameter speed prop to let the motor turn that fast. Prop for max static thrust, then back-figure the available power. That will get you an efficient prop setup.

If you take a fixed weight, and assume the ability to accelerate past takeoff speed on the ground, the only thing that determines takeoff speed is:

L = Cl*q*S

For a fixed runway length, then you would need to go figure out what the max possible weight would be with a take-off distance equation and then figure out takeoff speed and determine reynolds number from that.


With no limit on wing area, you should be able to have GW of 40 lbs and take off at less than 30 mph. Then you need to think about having excess power available to climb.