Lu,
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I guess low lifes' and uneducated individuals like myself...will just have to go through life believing that the blades have centrifugal force acting on them..."
You don't
have to go through life believing that, if you prefer you can heed the ramblings of those of us who have studied and used this theory in day to day work. If you prefer you can heed all those online resources I posted. Discussing with some of your friends in the industry is also a good idea. In the end, the decision is up to you whether you want to believe in centrifugal forces or not.
I'm just wondering what to tell my two year old about Santa Claus (Father Christmas). She'll see him at the malls and smell his breath, probably wonder why he's so jolly. Whatever I tell her, the choice is up to her to decide whether to believe in him or not.
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...what makes the blade fly in an almost radial position relative to the center of the rotorhead?"
Good question. This is one of the places that makes the existance of santarifugal force
seem so plausible.
Use the pen that Nick had you tie to a piece of string and then throw across the office. If you can't find it, it should be along the wall somewhere, not stuck in it. 2nd
If you spin the pen around your arm so the string is as close to vertical as you can get it without fouling on your knuckles (problem I have because they're so flattened and calloused from dragging... 3rd
). The pen wants to fly off in a straight line. The tension in the string accelerates the pen towards your hand. Add that acceleration to the pen's tangential velocity.
The tension diverts the pens velocity to continue to be tangential but also slightly upwards.
Hmmmmmm. I'm even confusing myself. Take a cone or a dunce cap. Place it on your head. Kidding. Place the cone on your desk, and away from the point, draw a short horizontal arrow. At the arrow head, draw a shorter arrow pointed towards the point of the cone. Now draw the resultant from the feathers of the first arrow to the point of the second. This is the direction that the pen gets deflected.
Of course, you have to throw out that cone and get a wider one because the angle of your string becomes more and more horizontal. Once at the horizontal, the tension in the string only pulls the pen towards your hand in one plane.
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...difficult to understand how a blade that is being dragged through a circular path will not flap up to an extreme if there is no force to balance out the lifting forces."
I'll let you in on a bit of a lie I've been telling. When the rotors are spinning, coned, producing lift, etc. the hub isn't supplying all of the required centripetal acceleration. That's what is really important, not the centripetal force. The hub pulling on the blades does happen, but once coned, that load is shared by a centripetal component to the blade's lift vector.
Knowing that, we can draw a force diagram. Vertical mast, coned blade. Forces are, load of helicopter: downwards from mast/hinge, weight of blade: downwards from blade CM, Lift of blade: approx normal to the blade, pull of hub: centripetal aligned with blade.
Those are all the forces, you'll notice right away that nothing is pointing outwards. Therefore the blade is not in equilibrium. An acceleration will happen, the net centripetal force will cause that required centripetal acceleration. The vertical forces will cancel if the helicopter is steady.
So, why doesn't the blade cone up to the vertical? Because there is no net force that will cause that motion.
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...if the blade is isolated from a linear inward pull by the flapping hinge and the lead lag hinge?"
One of the neat things about hinges is they transmit forces that are normal to the hinge axis. That's why your doors don't fall off when you open them. No matter how you align two hinges in sequence there is still at least one line that is normal to both hinge axes. There's no problem transmitting that force. Plus, as I mentioned above the blade lift vector supplies some of that centripetal acceleration.
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Must run. Centra Claus parade is downtown in 15 minutes. 4th