Qwazzy 123:

Think I would start with a APC 17 X 4W, and go to the 16 if it seems like too much prop, or any indication of overheating. In flying 3D, you want the engine to spool up without hesitation, and hold the upper rpms easially. A normal 3D'r is happiest just loafing around at slow speeds, a new learning curve for many who think WFO all the time is fun. The typical 3D machine is constructed very lightly and should not be horsed around at full throttle if you want it to stay togeather. ENJOY