I just got back from the first day of flying the UCD 46. I have a YS 63 turning a 13x6 APC prop. CG is about 5 1/2" back. The YS has plenty of power for flying around, it will hover and pull out but not with authority. Straight and level full power the ailerons would start to flutter, I think I will go with 4x40 hardware for these. Also I have not sealed the ailerons.
Knife edge required a little aileron.
The engine needs more right thrust.
With the current setup I could not get the plane to flat spin either upright or inverted.
Landings are very nice and slow.
Overall it is a nice flying airplane. More thurst would be nice but not more speed. I think I will try some different props.
The plane does not fly tail heavy at this CG.