QUOTE: The phrase 'Aerodynamic Precession' is used by Gareth Padfield &/or Gordon Leishman, two very respected helicopter dynamists.
When Messrs. Padfield and Leishman were attending physics and aerodynamics courses at university level what theory was taught to them? Was it gyroscopic precession or was it aerodynamic precession? Did the term gyroscopic precession evolve into aerodynamic precession by way expansion of engineering knowledge where computer analyses and complex testing proved the gyro theory to be incorrect? Or, was the new aerodynamic precession “invented” in order for these two gentlemen and other writers of engineering texts to sell more textbooks. Granted, I don’t have the engineering knowledge to fully understand all of what is in these textbooks but I have read several where the author(s) changed their theories over a series of textbooks.
In a case like this if the student were exposed to the first textbook and not all of them he /she would enter the world of engineering with a limited knowledge of the subject.
If in fact aerodynamic precession is the case there are a lot of pilots and mechanics in this world that were never exposed to this theory and they fully believe in gyroscopic precession. This does not make them stupid or place them in a time warp.
I have the training texts from different helicopter firms and although this material is dated these firms are still teaching that the rotor has two characteristics of a gyro. Rigidity in space and precession. The present FAA Rotorcraft Flying Handbook slightly downplays the importance of gyroscopic theory but they do not offer a replacement theory. Who is right and who is wrong. It depends on how and WHEN you were taught while in university or flight school and by extension mechanics school. Although some of you might object, both theories work.
Here is a question to ponder. On the Cheyenne helicopter control inputs to the rotor pitch horns are input from a “gyroscope rotor” suspended above the main rotor. When the main rotor responds to the input is it being displaced by gyroscopic precession or, aerodynamic precession?
QUOTE: Okay, Regis, FINAL ANSWER.....(from a physicist and helicopter guy) not only does gyroscopic precession have nothing to do with helicopters, the rotors don't even PRECESS!!!! (unless you stir the cyclic)
You can’t have it both ways. If rotors do not precess then both theories (gyroscopic precession and aerodynamic precession) go out the window.
Be gentle Nick’
