To evaluate the Robinson rotorhead, the first requirement will be to determine whether the two outer hinges are coning hinges (rotate in unison) or flapping hinges (rotate independently).
Is there a venturesome pilot who would be willing to;
~ Remove a coning/flapping hinge bolt, then stick it through a piece of white cardboard and then replace it on the rotor head.
~ Remove the cotter pin from the nut on the other coning/flapping bolt and replace the cotter pin with the innards of a BIC pen.
~ Bend the tip end of the pen so that it's ball is touching the cardboard.
~ Fly the hell out of the helicopter.
If there is a straight line on the cardboard pointing toward the bolt that is holding the cardboard in place; then they are coning hinges.
If the pen has randomly scrawled on the cardboard; then they are flapping hinges.
If the cardboard, the pen, and the nut are missing; then thank the almighty, whoever she may be, for a safe return.
If the missing nut is the pilot who tried this ridiculous experiment; then the prayers to the almighty must be modified slightly.
Anonymous
I've got to get a real job. 