To: rwm
Could you think of the amount of man hours the cheyenne would need just to keep it in the air? Complex gearboxes that shift the amount of power available to each of its rotating blades. The gyro head. The spring loaded control levers. All this covered in armour and sheet metal. The large avionics and weapons systems. All these componets being made by the cheapest bidder. And most of this technology being designed at the same time as the helicopter.
Regarding complex gearboxes the only thing complex was that it had one input and two outputs. There was no shifting involved. The propeller was controllable relative to pitch and when flying in the helicopter mode and then the propeller was in flat pitch. When in the compound mode the pitch was increased and the propeller provided thrust. When in a dive the pilot could retard forward motion by going into reverse pitch. The propeller was no more complex than that used on an aircraft. When in the compound mode the pilot would use only that amount of tail rotor pitch to counter the torque.
The gyro head was a picture of simplicity. Four weighted arms mounted on a constant velocity joint. The spring “loaded” control levers were not spring loaded and they were not levers. They were shaped similar to a horseshoe with the servo attached to one end and the pitch rod to the other. When the servo was actuated it would compress the “Horseshoe” spring which would transfer the compressive load to the pitch rod. This would apply a perturbing force to the gyro causing it to precess. In precessing, the control gyro would apply a load to the pitch horns causing the blade pitch to change cyclically.
Regarding the high maintenance man loading this is true. The Cheyenne was compared to a Century Series Fighter regarding complexity and was far too complex for Army personnel to maintain it. The same was true for the successor to the Cheyenne, which was the Apache. Because of its’ complexity the Apache is still maintained by contract personnel from Boeing.
Regarding the cheapest bidder I can’t speak to that because I came onto the Cheyenne program after the contract was let and I don’t know if the contract was sole source or if it was competitive. On the Apache the competition was between Boeing, Sikorsky, Bell and Hughes. Hughes eventually won the contract but they were totally unable to design and build the whole helicopter and almost all of it was subcontracted to other firms.
