To: CJ Eliassen
And BTW, if you attend the Robinson Factory MX course, you would learn the reason for the 72 degree offset. Call Frank and ask him yourself!!!
Since the rotorhead was designed before the helicopter was designed the reason for the 72-degree offset is the placement of the cone hinges. If they were closer to the teeter hinge you could have a 74-degree offset or if they were further away from the teeter hinge you could have a 70-degree offset. Since I am not going to the Maintenance course please let us all know why the offset is 72-degrees. There is nothing special about the blade cross section and the control configuration is like a Bell. Please tell us why there is a 72-degree offset other than the placement of the cone hinges. Did Frank plan it that way and in essence he determined the behavior of the blades even before the helicopter flew?
Points to ponder. The patent application for the R-22 rotorhead was filed in October 4, 1976. The first flight was in August of 1975. It would take at least a year to design and build the first article so the rotorhead design had to be finalized well before that time period. Give or take a few months the rotor was designed most likely in 1974. Of course this is pure conjecture relative to Franks' ability to predict the actions of the blades before he designed the rotorhead with the 72-degree offset.
As they say, the balls are in your court.
