To: Dave Jackson
As much as you and many others insist that gyroscopic precession has nothing to do with helicopter rotors I would suggest that you contact the training departments of Sikorsky, Boeing, Bell and even Robinson. I have the training text for the first three and they all address gyroscopic precession as the motivating force in changing disc position. They also address a phase angle of 90-degrees. Robinson on the other hand provides illustrations showing that the pitch horn is offset by 18-degrees from the teeter hinge and they address gyroscopic precession as being referenced in the text. The problem is the illustration they use is that of a Bell system which does not have an offset between the pitch horn and the teeter hinge and the supporting text states that there is a 90-degree phase angle still talking about the Robinson head. I personally believe that they would have a very difficult time in describing how the Robinson system can respond like a Bell, which has a 90-degree phase angle, and the Robinson has a 72-degree phase angle. According to what Nick Lappos stated the mechanics being trained would have to be a graduate engineer or physicist in order to understand the mechanics of the system. That is probably why in Frank Robinsons’ response to me he indicated that we wouldn’t understand how it works.
Now do you know where my confusion stems from?
Regarding the demise of the sinusoidal swashplate it has already happened. The Lynx does not have a swashplate but it does have an isolation bearing that separates the rotating elements of the flight control system from the stationary bits. The Lynx has an offset similar to the Robinson (15-degrees) and with out the electronic flight control system the blades would dip down to the left with forward cyclic. There could be a thousand different ways of eliminating the swashplate but those systems would be so complex as to be rife with single point catastrophic failures.
[ 19 November 2001: Message edited by: Lu Zuckerman ]