Coriolis vs Conservation of Angular momentum

[Vessbot]

Originally Posted by Ascend Charlie

Jeez, Vessbot, I hope you are just being a troll and that you don't actually believe in helicopters having precession.

Given that every other rotating body in the universe exhibits this property, why wouldn't a helicopter rotor?

"Precession" is an easily accepted idea that allows Trump-brains to grasp the idea that it takes time for the force of a control input to accelerate a blade mass and make it move to where you want it, and while that time is elapsing, the blade is rotating around the mast. Usually it takes between 72 and 90 degrees of turn before the rotor gets to the desired position, but by then it is already receiving signals to get back to where it was, or go even further the other way.

Why would it take any time? Hint, it has nothing to do with inertia or slow acceleration. It would happen the same even if the force was applied in a single impulse, a knock rather than a push; and the resulting deflection of the blade was instantaneous. The answer is that it is impossible for the blade to teleport to a position higher than it currently is, which is what would be required for the disk to tilt with no phase lag. The best that can happen (again, even with instantaneous knock and deflection) is that the path of the blade is changed upward, reaching a maximum 90 degrees later.

For another visualization, say you have a spacecraft in an Eastbound orbit, perfectly tracing the equator. When crossing the prime meridian, you fire the engine for a brief moment with the nose pointed North. What's gonna happen? You'll change the flight path from purely Eastward, to slightly Northeast. At which point along your new orbit will you reach the highest North latitude? Not over the prime meridian, again that would require teleportation. You only began your new path at the intersection of the equator and the prime meridian; the maximum North latitude you'll reach is at 90 degrees East longitude.

A gyroscope it ain't. And it doesn't take exactly 90 degrees to take effect, like a real gyroscope would. The late Lu Zuckerman, when shooting down the Gyroscope Gang, would ask "where is the missing 18 degrees?" when he spoke of the R22, which displayed a phase lag of 72 degrees.

There are higher order effects stacked on top of the basic 90 degree one, changing the final outcome slightly. I wouldn't mistake this for the basic effect underneath lacking a behavior fundamental to all rotating bodies. See what I wrote earlier about careful accounting of multiple effects happening simultaneously.

​​​​​