To: Dave Jackson
This coupling causes the pitch angle to reduce as the coning angle increases.
If the pitch horn extends beyond the cone hinge when the blades cone pitch will be added to the blades not removed. This is not such a bad thing. However when the pilot enters into autorotation and he moves the collective to the full down position the blades are still coned and the pitch can not return to the full down basic pitch setting and this will effect the autorotation characteristics.
If the effect is great enough the pilot will report this to the mechanic and he in turn will adjust the pitch links taking the blades below the basic rigged neutral pitch setting.
This is my basic argument when Frank Robinson stated that he had considered incorporating a 90-degree pitch horn. If he had done so the helicopter would be uncontrollable. Extending the pitch horn 1” or so beyond the cone hinge will not make the helicopter uncontrollable but it will effect the autorotation characteristics.
The entire rigging procedure on the Robinson helicopters is contrary to the rigging procedure on every other helicopter and can lead to some very interesting problems for the mechanics.
