To: Droopystop
You send your kids to school and buy them books but their understanding of the different subjects is based on the schools you send them to and the books you buy them and how well they assimilate the information presented.
If you attended engineering university 20 to 30 or more years ago you would have been taught gyroscopic precession and how it applied to differing rotational objects from a spinning rotor in an aircraft instrument, an aircraft propeller or even the rotor of a helicopter. It seems that universities are now teaching that gyroscopic precession does not apply to helicopter rotors. Instead they substitute all types of calculations and formulae to explain how the rotor system responds to input.
Even though it doesn’t apply to helicopters (any more) it still applies to gyro instruments on an aircraft, the propellers on aircraft, the wheels on a motorbike or bicycle. A propeller you ask? When an aircraft maneuvers the gyroscopic turning moment on the propeller causes the propeller to bend to the point that the blade tips depart the rotational plane. When the maneuver stops the “centrifugal” moment will restore the blade position.
I managed a training program for the US Army teaching maintenance on helicopters. We taught gyroscopic precession and the mechs. and maintenance officers would ask, “if the blades are independent from each other then how could they respond as a disc”?
We had the model shop construct a gyro that had twelve arms each weighing several ounces. These weights were attached to a disc, which in turn was driven by an electric motor. We constructed a rudimentary swashplate, which allowed perturbation of the independent weights on the disc. The disc was brought up to speed and when we input a perturbing force the independent weights would respond 90-degrees later until the rotating weights (rotor disc) were all tilted 90-degrees after the control input.
It is easier to use gyroscopic precession because it is easily understood and, it can be demonstrated. Is it right or wrong? It depends on where you went to school and of course, when.
