RE: 4bladed walkera
An odd number of blades cancels harmonics and will be smoother. On my CGS Hawk ultralight, the three blade prop was something everyone raved about. I had a three blade UltraProp. I had a two blade wood that resonated like crazy, it scared me but lots of people fly them. They avoid the resonant peaks. I said none of that and got the UltraProp.
SB