To: Helo Teacher
You say tomato and I say tomahto. You say flapping angles and I say flapping loads. It is the high flapping angles that induce the loads reflected at the rotor head so we are saying the same thing but using different words.
If you can't accept my theory that the design of the rotor head requires the input of a right bias beyond the rigged neutral setting of the cyclic then you can in no way understand what I am talking about when I state that in countering a zero G condition the pilot must be extremely careful in how he pulls the cyclic back and in which direction relative to the centerline of the aircraft.
My theory is that the pilot must offset the cyclic to the right in order not to fly to the left. In encountering a zero G situation he must move the stick back:
If he pulls back from the offset cyclic position he will not add to the right roll caused by the tail rotor.
If he pulls back and slightly to the left until he is on a line with the rigged neutral centerline he will add to the right roll and lose control
If he pulls back and passes over the centerline of the rigged neutral position he will not add to the right roll.
If he pulls back and further to the left he will generate high flapping loads (angles) and cause mast bumping.
This is all contained in the diagrams.
This is one scenario as visualized by myself
regarding mast bumping. Actually ther are two but one involves blowback as a result of retreating blade stall. I will address the first theory not the second.
When the pilot for whatever reason encounters high flapping angles and the resultant loads, the blade is flapping in an uncontrolled manner. Normally, when in flight the blades are coned so the spindle is separated from the down stop. When the high flapping angles are present there is a possibility that the balde will drop down to its' pure radial position and possibly beyond and in doing so the spindle contacts the stop.
If the contact force is strong enough it can act as the moving force on a first class lever and cause the rotorhead to pivot on the teeter bolt and make contact the mast stops with such force as to cause the mast to fail. What are your fellings about that (anyone)?
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The Cat