Originally Posted by
Vessbot
Are phase lag and gyroscopic precession not the same thing? How are the physics different?
Vessbot Thanks again for your input, I think I'm with you now. The conservation of angular momentum accounts for the rpm change, but the 'puzzle' doesn't end quite yet. You could go a step further to analyze the rotor system once the rpm change has actually taken effect, which would be the blade mass deflection perpendicular to direction of rotation, when viewing the rotor system from the non-inertial frame of reference, i.e. Coriolis effect. I think we are on the same page, but that comprehension is about the extent of my brain power. I need to take note from
Ascend Charlie
To answer your question, no. Gyroscopic precession and phase lag are not the same. There is no doubt that a rotating rotor system serves as a gyro, however, gyroscopic precession is only a small part of the Phase lag 'ingredients'. Phase lag varies greatly in helicopter rotor designs. I've heard numbers from as little as 50 degrees to over 100 degrees. Unlike a typical gyro, a rotor system experiences not only dynamic inertial inputs but also aerodynamic inputs. Blade hinge offset and design plays a a big role too.