Rotor Lift with the wind and into the wind.

if you turn 180 then it would be the left rail surely? On the other set of track that is
 
if you turn 180 then it would be the left rail surely? On the other set of track that is

No

Um, if you turn 180 and examine the other right rail, is it also the most worn?

Yes.

In north hemisphere, when you move in any direction (exept exactly from E to W or W to E) the Coriolis effect produce a force to the right.
In fact, Coriolis effect is very easy to understand (if not, it's probably an effect of my bad english):
When you move from South to North, you become closer to the axis of rotation of the Earth (on the equator, you are at 6350 km of the axis; at 45° of north latitude, you are at 4500 km of the axis). As you are spinning with the Earth from West to East, like a skatter squeezing up his arms, the conservation of kinetic momentum make you accelerate in the direction of your rotating movement, so to the East (so to the right of your movement from S to N).
When you go from N to S, you move away from the axis of the Earth, so you deccelerate, so you are subject to a force to the West, so to the right of your movement.

I suppose you know that it is for the same reasons than the teeter axis of our rotors is a few centimeters above the plan of rotation of the rotorhead, avoiding this way the need of a trainee axis on the base of the pales (sorry, I'm not sure to use the right words in english).
 
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...I suppose you know that it is for the same reasons than the teeter axis of our rotors is a few centimeters above the plan of rotation of the rotorhead, avoiding this way the need of a trainee axis on the base of the pales (sorry, I'm not sure to use the right words in english).
You have lost me there, Bruno. The way I understand it, the teeter axis should be in line with the imaginary line connecting the CGs of both rotor blades in flight. In other words, the whole rotor CG, in flight, should pass right through the teeter bolt.
 
Hi Udi

Glad to have met you at Mentone. I know that the rotor on the RAF is tilted 3 degrees to the left. I have heard that this is to compensate for the unequal lift and the extra load with two people.
 
Hi Thom!!!!
That's all; just following the thread and wanted to say I enjoyed meeting you and your wife.

OK back on topic.
 
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If you stand at the center and walk toward the rim of a rotating carousel, your body acquires kinetic energy and exerts a torque against the carousel that opposes rotation.

Same with a train traveling north or south.

The effect is greatest near the geographical poles and minimal when crossing the equator.
 
You have lost me there, Bruno. The way I understand it, the teeter axis should be in line with the imaginary line connecting the CGs of both rotor blades in flight. In other words, the whole rotor CG, in flight, should pass right through the teeter bolt.
Viewed from the rotorhead axis, Udi, there is an imaginary Coriolis force in a rotor without undersling.

As the blade of a coned rotor flaps upward, its CG moves nearer the rotational axis; the CG of a downward flapping blade moves away from the center of rotation.

But like a rock being twirled on a string, a hinged blade rotates about its own axis; not caring where the rotorhead axis is pointing.

A seesaw rotor without undersling would produce some nasty stick shake. Because of coning, as the rotorhead was tilted, the blade would have to be swept through an arc. This would occur 2/revolution in forward flight. The total CG of such a rotor is forced to rotate in a 2/rev circle.
 
Hi Udi

Glad to have met you at Mentone. I know that the rotor on the RAF is tilted 3 degrees to the left. I have heard that this is to compensate for the unequal lift and the extra load with two people.
Hi Thom - It was great meeting you and your wife as well. I believe the RAF rotor is tilted 3 deg. to compensate for prop turning torque. The teetering rotor is compensating for lift dissymmetry all by itself (unless you have too much friction in your teetering bolt).

John - is was great meeting you too. I only spent a couple of hours with you but I could feel that energy bubbling inside you. I bet you are hard to keep with (especially when you are "all-in") ;)
 
Udi I really enjoyed talking to you. I wish to come visit and just sit and listen and suck out all the knowledge you casually toss out to we mere mortals.

You all were so cool and friendly Mentone was truly GREAT!!!! I can't wait to see all you guys and the rest of you rotorheads there next year!!!
OK back on topic, sorry but new friends and all I could not help myself saying hi!!!
 
Chuck, I don't see what that has to do with Coriolis. The way I visualise this, the CG of a teetering rotor hinged without undersling moves back and forth over the axis of rotation twice/rev. When the blades are at 90/270, the total CG is right over the axis of rotation and when at 0/180 the total CG is back of the axis of rotation due to flapping. We are using undersling to hinge the rotor at, or close to, the total CG so there is no shifting of mass when the rotor is flapping.

I can see the Coriolis effect in a fully articulated rotor where the blades flap independently, not in a teetering rotor. I must be missing something...
 
You have lost me there, Bruno. The way I understand it, the teeter axis should be in line with the imaginary line connecting the CGs of both rotor blades in flight. In other words, the whole rotor CG, in flight, should pass right through the teeter bolt.

Udi,
C.Beaty explain in post #27, better than I can, what I wanted to say.
It's too the reason why three blades rotors must have a trainee axis, as it's not possible to align the four points on a same plan.

Bruno
 
One picture is worth one thousand words, Udi.

Viewed from the rotorhead axis, the upflapping blade’s CG moves nearer the axis of rotation and must speed up if momentum is to be conserved. The downflapping blade’s CG has moved farther away and must slow down if momentum is to remain constant. That’s Coriolis for you.

Viewed from the rotor plane axis, nothing peculiar is happening except the total CG is forced to rotate in a 2/rev circle when there’s no undersling.
 

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Chuck "when there’s no undersling" I did a search of undersling to see how it's applies but I can't find a definition. Where can I find what this is, sorry for ignorance to interrupt, but maybe someone else doesn't know either and I was following along so well until now.
 
Ok, I got the Coriolis effect Chuck. The Coriolis effect would induce in-plane moments if the rotor was not underslung. That, I suppose, is a good reason of the drag hinges in an articulated rotor.

I still don't think the Coriolis effect is the main reason for the undersling. The way I see it, the main purpose of the undersling is to minimize the 2/rev shift of rotor mass around the axis of rotation that is a result of flapping - not Coriolis effect. And... it seems to me that the total CG would draw a line, not a circle. Think about it - when the rotor is at 90/270 the total CG is right above the (non underslung) rotor axis.
 
Udi, the figure on the left represents a seesaw rotor with CG above the teeter bolt. 180º of rotation later, it is in the same position. At 90º and 270º, the middle ball is aligned with the rotorhead axis. How does it get from one position to another? By following a circular path. Think about where it might be at 45º and quadrants thereafter.
***********
All, the second figure ought to explain undersling to you. The object is to get the rotor’s CG in alignment with the teeter bolt to minimize vibration.
 

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Ohhh! Thanks not what I was thinking at all!!
 
... I suppose, is a good reason of the drag hinges in an articulated rotor.
Drag hinges is what I improperly named trainee axis.

I still don't think the Coriolis effect is the main reason for the undersling...the main purpose of the undersling is to minimize the 2/rev shift of rotor mass around the axis of rotation that is a result of flapping - not Coriolis effect...
It is the same phenomen, different analysis depending of the referentiel you use. Coriolis effect is an easy way to understand what happens when you are in the wrong referentiel, it's not real forces, the only physical law involved is inertia.
If you continue your analysis, 90/270, 180/0,... you will see that the move of CG is a circle.

Bruno
 
Bruno, you’re a bright* guy. If I tried to explain this in French, I’d look like a total idiot.

*means very intelligent
 
Thank you for your explanations to us Mr Beatty, probably done many times but you seem patient enough to do them again to help us understand better.
 
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