To: Nick
The V-22 and I assume the 609 have far fewer rotor controls than a conventional helicopter. The collective and cyclic controls are limited to the two sticks, which are directly linked to variable differential transformers. These VDTs send a signal via the computer to the servos of which there are three dual servos connected to the swashplate allowing the prop rotor to function as a conventional helicopter rotor. The electronic flight control system functions in the exact same manner as a CH-47 but no mechanical linkages. The same servos are used to adjust the pitch of the prop rotor which then functions as a propeller on a fixed wing aircraft when in the airplane mode.
The rigging of the all controls from what I understand is done electronically and this includes the servos that are used in the airplane mode.
I bitched and moaned while on the program about the higher than anticipated cycling of the hydraulic system but was ignored. The Prop Rotors are mounted in an elastomeric assembly and when the aircraft is in the Airplane mode any maneuver will cause the Prop to precess just like an aircraft propeller. The aircraft propeller however is rigidized by the support bearings on the prop shaft so they can’t precess but in some cases the tips will deflect. When the Prop Rotor precesses there are flapping sensors that will command the servos to bring the prop Rotor back to the radial position. With a great deal of maneuvering while on a mission the hydraulic system will operate at a very high duty cycle which can effect systems reliability. I was told that even though Boeing built the hydraulic system it was a Bell problem because it was the Prop Rotor that caused the problem. Boeing never told Bell so nothing was ever done.
