Lu,
Grey Area tried to explain something to you the first time. You merely repeated your lines. So he merely repeated his, but only this time you agreed with him! How did that work?
You said: >>To: Grey Area
I totally agree with you. Collective causes coning and cyclic causes flapping. All I was doing is to explain what is happening when the pilot pulls collective.<<
But Lu, you are wrong. That is NOT what Grey Area said. Collective DOES NOT cause conning (although it can). What he said was – Conning is the term applied to COLLECTIVE change of angular displacement…NOT a change DUE to collective. Do you have any idea of the distinction? It goes back to your misapplication of the term conning angle. I say again: You need to read the definition of this prior to continuing any meaningful discussion on this point. Simply stating your definition IS NOT a substitute for the actual definition. While you are at it, I think you provided an “explanation” not a “definition”, so look up the word definition too!
Perhaps then you will be able to respond to my points with some form of coherence, as I have shown below in sticking to the original points
1. Flapping has nothing to do with cone angle.
Lu Response:
The way I learned it flapping of the blades above the radial position is what prescribes the cone angle. The higher the flap the greater the angle.
My Response:
The way you learned it IS the problem, go and get a definition out of all those books you quote about gyroscopics, etc. “Radial position” is not a term applicable in this discussion. If you get the definition of cone angle you will find no reference to flapping (or radial position). What Grey Area was saying is pertinent here. Blades can flap independently – ie CYCLICALLY, ie flap to different positions dependant upon where they are in the rotational CYCLE. That is why it is called CYCLIC flap. Again, you STILL need to learn the basics of flapping to equality to grasp this. Flap is not the term we apply to a collective (all together) change in angular displacement. Therefore, your statement that >>the higher the flap the greater the cone angle<< CANNOT be correct. I
If it WAS correct, lets look at how you proposition holds up. Aircraft bunts. Blades flap down at front and up at rear. Therefore, has the cone angle increased (viewed from rear) or decreased (viewed from front)? Aircraft now pitches nose up, blades flap up at front, down at rear, what has happened to the cone angle Lu? NOW do you see the flaw Lu?
2. Precession has nothing to do with cone angle.
Lu’s Response:
Precession has everything to do with the cone angle. Whether you believe in aerodynamic or gyroscopic precession precession is what causes the tilting of the disc and as a result it creates an angular difference between the driving axis and the driven axis.
My Response:
Tilting of the disc IS NOT changing the cone angle. See the argument under (1). Precession is applicable to flapping (and understanding of flapping to equality will again be required to grasp this), therefore precession (like flapping) has nothing to do with cone angle. Now you have introduced more terms: driven axis and driving axis. If you stick to the common language suggested by Grey Area, then I might be able to examine your statement, because (and remember – I am no aerodynamicist) I have no idea what you are saying with these terms. Suffice to say, cone angle definition does not include these terms.
3. While the tip path plane changes with the introduction of cyclic, and the disc is tilted left (American helicopter) due to tail rotor roll, neither of these have anything to do with cone angle.
Lu’s Response:
As I indicated above compensation for tail rotor propeller effect will cause a change in cone angle. That is why I removed it from the equation and referenced the viewing angle for the rotor system.
My response:
No Lu. Tilting the disc has nothing to do with cone angle because this is achieved cyclically as per the arguments above in (1). Doesn’t matter why you are tilting the disc (tail rotor propeller effect or what) it is not cone angle.
I believe you are mixed up with the terminology. A “DISC” does not actually exist, it is merely the term applied to the circle scribed by the tip path plane. The disc does not tilt as a solid, in fact the tip path plane changes due to the different flap position of the blades as they go around, creating the “illusion” of disc tilt. Grasping this may also help you understand why countering the pitch up and roll during retreating blade stall with cyclic can severely exacerbate the problem – it is not a disc to be changed, but individual blades that need consideration.
Dave,
I only have eyes for the ice skater. I cannot get my head around your suggestions - sorry – I have a brain only for ice skaters too! Je ne comprendez pas. (or something like that).
