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#251
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Backwash Causes Lift?
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#252
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Backwash Causes Lift?
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#253
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Backwash Causes Lift?
On Oct 7, 10:07 pm, Mxsmanic wrote:
Le Chaud Lapin writes: If that is the case, what is pushing the air? You may be able to get past this by considering that the airfoil actually turns the flow, rather than push or pull it. It turns the flow downwards, and this acceleration of the air mass engenders an upward force that is lift. The airfoil turns the flow downward.... What air gets turn downward....the air on top of the wing or the air on the bottom of wing? -Le Chaud Lapin- |
#254
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Backwash Causes Lift?
Mxsmanic wrote:
writes: When in straight and level flight, the air flow through the rotor blades of a gyrocopter is upward. But the net movement of air is downward for the entire aircraft, which is why it flies. The rotor acts as a large airfoil. The disk defined by the rotor blades of a gyrocopter or gyroplane is tilted slighty back. The air always enters from the bottom of that disk and exits from the top. If it doesn't, the aircraft stops flying. There is nothing after leaving the rotor disk to change the direction of air flow. The airplane, helicopter, gyrocopter, and gyroplane all fly straight and level for the same reason and it isn't air being deflected downward. -- Jim Pennino Remove .spam.sux to reply. |
#255
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Backwash Causes Lift?
On Oct 7, 11:02 pm, flightoffancy wrote:
Did you mess with NASA's online simulations of airfoils? Yes, 15 minutes ago, in fact after taking a break from my very tedious work. Those suggest that the air both "on top" and "on the bottom" of an airfoil get turned as the airfoil's AoA changes. Those have to be put in quotes since an aircraft (with the proper engine) can be flown upside down and in other orientations. I did notice the turning. The article is claiming that the upper surface of the wing "turns" the upper flow. Link: http://www.grc.nasa.gov/WWW/K-12/airplane/right2.html I must admit that I am having problems with this explanation. It is extremely vague? What is the turning? How, exactly, does the wing "turn" the flow. The air is made up of molecules. If it is upper surface of the wing that is turning does air molecules so that they have a velocity component that is downward, how is this happening? Since when, could one body, A, of any kind, that does not involve gravitational or electrostatic fields, induce another body B, to move in a direction that has a component vector that is aimed directly at B? Also NASA does not just explain why the longer length theory, the Newtonian theory, and Bernoulli theories are incorrect, they also elaborate what the correct equations to properly calculate observed lift are, though I didn't see an example calculation. So they do say what is correct, as well as what is not.- Hide quoted text - True. This "turning" theory of NASA makes me suspicious. If anyone else has any qualtitative explanation of what they mean by the upper surface of the wing foil turning the air so that it has a downward component in its velocity, I would like to see it. Finally, I do agree that the geometry, AoA, etc...interacts with the atmospher in such a way that the net result of the flow on the top surface of the wing is back and downward. What I don't see is the how the wing itself is "turning" that flow. -Le Chaud Lapin- |
#256
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Backwash Causes Lift?
Le Chaud Lapin writes:
The airfoil turns the flow downward.... What air gets turn downward....the air on top of the wing or the air on the bottom of wing? Both, but mostly air from above the wing (a great deal of air, in fact). |
#257
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Backwash Causes Lift?
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#258
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Backwash Causes Lift?
On Oct 7, 11:58 pm, Le Chaud Lapin wrote:
On Oct 7, 11:02 pm, flightoffancy wrote: I did notice the turning. The article is claiming that the upper surface of the wing "turns" the upper flow. Link:http://www.grc.nasa.gov/WWW/K-12/airplane/right2.html I must admit that I am having problems with this explanation. It is extremely vague? What is the turning? How, exactly, does the wing "turn" the flow. The air is made up of molecules. If it is upper surface of the wing that is turning does air molecules so that they have a velocity component that is downward, how is this happening? Since when, could one body, A, of any kind, that does not involve gravitational or electrostatic fields, induce another body B, to move in a direction that has a component vector that is aimed directly at B? I just re-read the link above very carefully, and unless I am mistaken, there is a *huge* amount of hand-waving going on here too. Sigh. "Turning" a flow? What would Newton say. It's magic. Yes, we all know that F=ma, and "a" is the time derivative of velocity, a = dv/dt, and that v has a magnitude and a direction, and that if you change either magnitude or direction, you have a force...that's all fine... They do not specify how the wing turns the air. They show a picture of air flowing backward on top of a sligtly-angled wing. Then they write: "For a body immersed in a moving fluid, the fluid remains in contact with the surface of the body. If the body is shaped, moved, or inclined in such a way as to produce a net deflection or turning of the flow, the local velocity is changed in magnitude, direction, or both. Changing the velocity creates a net force on the body. It is very important to note that the turning of the fluid occurs because the molecules of the fluid stay in contact with the solid body since the molecules are free to move." "the molecules stay in contact with the solid body"...????????????? Why? What incentive do the molecules have to stay in contact with the solid body? Is there a sign on top of the wing that reads: **** NOTE: ALL MOLECULES, YOU ARE HEREBY ORDERED TO STAY AS CLOSE TO ME AS POSSIBLE. **** Are there little molecule-sized pina coladas on top of the wing waiting for the molecules to drink? Even if there is a thin layer of air remaining in contact with the wing for mysterious, magical reasons, what about the layers above it? What incentive do those layers have "try and stay in contact with the wing"? -Le Chaud Lapin- |
#259
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Backwash Causes Lift?
Mxsmanic wrote in
: writes: When in straight and level flight, the air flow through the rotor blades of a gyrocopter is upward. But the net movement of air is downward for the entire aircraft, which is why it flies. Nope. Wrong again, dip****. Bertie |
#260
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Backwash Causes Lift?
Mxsmanic wrote in
: writes: There is nothing after leaving the rotor disk to change the direction of air flow. The airplane, helicopter, gyrocopter, and gyroplane all fly straight and level for the same reason and it isn't air being deflected downward. No heavier-than-air aircraft flies without deflecting air downward, Yes, they can, and do. Dynamic lift is usually at play but is by no means required. Bertie |
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