Dave said, "
I believe that the analogy with the gyroscope starts to lose its validity as delta-3, flapping hinge offset and rigid rotors are introduced. It will probably lose more of its validity as 'smart materials' are incorporated into the rotor blades."
If you apply a moment to a rotating body, the result must be a vector sum of the original angular momentum and the impressed angular momentum. Doesn't matter if there is an unusual control geometry, aerodynamic effects, etc. Gyroscopic precession is actually an illustration of that effect. Many basic helicopter texts use gyroscopic precession to mean that effect. If you use this latter definition, then it's valid as long as the rotors are turning.
"
The helicopter rotor is an aerodynamic device. I believe that the best way to describe its operation...."
I try to talk only about the motion of the rotors due to a force being impressed upon them. Yes, some of those forces are generated aerodynamically. How they are generated does not change the effect they have on the system.
Rotors are also accelerated by an internal combustion engine. Should that be in a theory on why rotors lag by 90 degrees?
I really don't care what you want to call it. To me, rotational dynamics says it all. So does many other terms. I don't see that specifying the origin of these forces creates any deeper understanding of the concepts, rather it may confuse.
I'm sure given the budget we could build a model of a rotor system that generates "lift" through magnetism or something other than aerodynamics. It would exhibit a 90 degree lag as well.
Matthew.
[ 21 November 2001: Message edited by: heedm ]