Originally Posted by
maxtork
Ok I have a few questions for the engineer types. Here is what I think I know...the questions comes after:
1-Gyroscopic precession causes the rotor system to react 90 degrees out of phase from the control input (generally speaking, see below). On a 2 bladed teetering system this seems to be the case anyways.
2- The amount of flapping hinge offset can change that 90 degrees to something smaller. The more offset the less phase lag?
3- Pitch link phase angle offset is also a factor. If the pitch link is 45 degrees in front of the blade then that would be 45 degrees removed from the 90 gyroscopic precession. If 45 degrees behind the blade then it would be added to the 90 degrees.
Now here are the questions-
1- Is that everything that would effect the input phase angle? What else am I missing?
2- Is this something that is engineered on paper before they ever make parts? Or does one need to design build and run a rotor system on a whirl tower to see just what the actual phase angle displacement is and then design the flight control system to tilt the swashplate in the right direction? I would guess it is the former not the later but seems like it might be a tough thing to get right on the first shot and difficult to adjust for if you miss the mark.
Thanks
Max
I was lucky enough to meet this guy a few times before he passed. Maybe not definitive as he always said but good info.
RW Prouty wa
s a staff engineer-flying qualities at Hughes Helicopters Inc, in Culver City, Calif. He jokingly refers to himself as a "journeyman engineer who has journeyed, over the past 28 years, from Hughes Helicopters to Sikorsky Aircraft to Bell Helicopter to Lockheed's helicopter program and finally back to Hughes" He further observed that "helicopter people tend to go around in circles." As an aerodynamicist, his experiences included preliminary design. performance and flying-qualities analysis, wind-tunnel testing, and flight testing.