Vorticey and
Lu,
Reread what I said. Text books will tell you that centrifugal force is an apparent, not a real, force. I acknowledged that while it may be apparent, we have all felt it, and it does make some physics easier. It's a good tool to use, but is not a real force.
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A body in motion tends to stay in motion, in a straight line..." you know who wrote that. The blade is a body. It doesn't want to spin around, it wants to fly off tangentially in a straight line. The hub pulls on the blade (mechanical force) accelerates it so the blade's velocity vector changes in direction. This is what really happens. There is no magical hand that tries to pull the blade away from the helicopter.
Same thing happens with your tape measures, vorticey. They just want to fly off in a straight line tangential to the axle, but eventually the strength of the spring will stop them from flying out and then it will pull them into orbit around the axle.
Coriolis is similiar.
Coning is easily explained without referring to centrifugal force, but the forces are not balanced, something which bothers some. They must be unbalanced because there is a net force that is accelerating (turning) the blade. When you draw a picture, it is often easier to explain it using a centrifugal term and ignore the blades motion rather than showing a force imbalance.
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Grey Area, what you have explained is great. That is the same theory that I've been using to explain gyroscopic precession, aerodynamic precession, and "flying the blades to position". My point (and others) has always been that those theories are all just another way of explaining the same thing. Unfortunately, pendulum-like motion and flapping frequencies are not normally taught to pilots, so some of us keep trying to explain what has been taught.
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gyro with a flapping hinge"
By definition, it's not a gyro. It does have some properties of a gyro, one of them is that apparent lag. In this case the lag is not going to be 90 degrees. It will be less, actually value is easily calculated. It won't even look like a lag, since the oscillations of the parts outboard of the hinge would be at a higher frequency than the whole system.
A helicopter with offset flapping hinges has a driving force on the blades that is mechanically in phase with the rotor, so you don't see the higher frequency oscillations, instead you see a phase angle of less than 90 degrees (all else being equal).
Matthew.
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