Dave said,
- The relative mass and rpm of a gyroscopic is high visa-vie the relative mass and rpm of a helicopter rotor.
The rpm of a gyroscope is higher, but the mass of a typical helicopter rotor is higher. What really matters is the magnitude of the angular momentum. Angular momentum is a function of rpm and the distribution of mass about the center of rotation (moment of inertia). Without being given specific examples, it's hard to say which has a higher angular momentum, but the one with the highest will be the hardest to stop.
Try stop a gyro with your hand. Now try stop a helicopter rotor with your hand. Which one was easiest? That one had less angular momentum.
Higher angular momentum only means that when you apply a force, it has less of an effect than if you applied that same force to something with lower angular momentum. That is why a gust of wind hitting a rotor that is slow during startup can result in much more blade motion.
- The relative aerodynamic activity of a gyroscopic is low visa-vie the relative aerodynamic activity of a helicopter rotor.
When I think of a gyroscope, I think of something that has been designed to not interact with air. However helicopter rotors are designed specifically to interact with the air. Therefore, I agree, but I don't see how this is significant.
I've heard you mention your aerodynamic precession theory before. I don't think you're wrong, I just think you're giving another name to something we already understand. If you follow through my very long post where I describe why an apparent 90 degree lag takes place, I think you'll find that the theory behind it is the same for gyroscopic precession and aerodynamic precession.
I say we stop confusing people. Don't use the term precession. It is absolutely wrong. Don't use the term Gyroscopic Precession, it's not theory, it's just an example of something that behaves similarly. From now on to avoid confusion, let's talk about
non-relativistic rotational kinematics.
Matthew.
[ 20 November 2001: Message edited by: heedm ]