Hal - Like Spindizzy I have my rotor blades held by a single nut & bolt. I am sure they don`t move from their alignment in flight - upon landing they are in the same position as before flight. The blades are clamped sucurely, I have sandpaper on both mating surfaces, quite rigid, but will swivel if the plane tips over on landing, thereby saving the blades etc. On my larger plane I do have additional `pegs` of thin dowel, but on my .15 powered plane the single bolt per blade is fine. I check tightness after a flight, they have never worked loose. The delta angle is maintained at all times.
Colin