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#261
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flightoffancy wrote in
: In article , says... The downwash thing is wrong. Yes, there is some dispacemtn of air that causes lift, but it' only a minor contribution in the bigger scheme of things. I admit to being a relative retard on this issue (not as retarded as a non-pilot probably is, but not as educated as an aeronautical engineer). I thought I had read in numerous books during training that the primary component of lift is the air that gets knocked downward by the wing. I was calling that "downwash". Maybe my concept of downwash is wrong, maybe it's a separate consideration from the air that gets knocked downward by the airfoil. Hell I might not be remembering any of that correctly. Anyway you say downwash is minor. Well okay. But then what are the major contributions that cause lift in the bigger scheme of things? Bernoulli, Period, Full stop, end of story, finito, spaghettio, Finis sayonara, Good lucko, Bertie |
#262
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Mxsmanic wrote in
: Bertie the Bunyip writes: Actually, yes it is. Show me an aircraft that does this. Does what? Makes a period? Bertie |
#263
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Mxsmanic wrote in
: 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. Mmm, nope. Bertie |
#264
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Mxsmanic wrote in
: 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). Nope Bertie |
#265
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Le Chaud Lapin wrote:
"the molecules stay in contact with the solid body"...????????????? Why? It's what gases do. The particles are constantly bouncing away from each other. This is pretty simple physics - something that should almost be intuitive. If you have a cylinder of gas with an air-tight piston and pull back on the piston and double the size of the volume do you seriously think the gas will not expand into the other half as fast as it can to try and stay in contact with the piston? If you are having this much trouble on a basic concept of gases, then I see no value in you or anyone else investing time in dealing with your questions, which you chose to post to an inappropriate newsgroup anyway. Grumble. Now I recall why I had established a personal policy to stay away from discussions of aerodynamics on this newsgroup: futility avoidance. |
#267
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Matt Whiting wrote in news:lRdOi.234$2n4.16576
@news1.epix.net: Bertie the Bunyip wrote: flightoffancy wrote in news:MPG.2172e043702d7a5d989681 @news-server.hot.rr.com: In article , says... "Nope, wrong" to which claims I made? I freely admit that my knowledge of aerodynamics is lacking. But I'm absolutely correct about Lapin's training (or utter lack thereof, in this case). It's completely absurd for someone who has not studied aeronautical engineering to stand up on a soap box and announce that the work of several generations of aeronautical engineers is WRONG -- and that he's leading the charge to finding out what the facts of aerodynamics really are. Lapin does this kind of thing on countless other news groups, especially computer science groups. He denounces decades worth of work as inadequate or completely wrong, claims he has the right answer or merely wishes to find the right answer, with the result that nearly everyone on the group calls him a crank. Anyone who is really an expert in the area he's challenging quickly figures out his meager explorations of the subject are not worth spending any time participating in. Lapin believes that he is here to TEACH us. If you can find hundreds of threads started by LCL on Google groups. He's an incorrigible usenet troll. The downwash thing is wrong. Yes, there is some dispacemtn of air that causes lift, but it' only a minor contribution in the bigger scheme of things. Bertie And what about a hovering helicopter? What is holding it up? Air? Bertie Matt |
#268
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How does a gyrocopter fly because the airflow over it's "wing" is going up.
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#269
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"Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote in
: How does a gyrocopter fly because the airflow over it's "wing" is going up. They're gliders. The same rules apply. Bertie |
#270
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On Oct 7, 7:10 pm, Le Chaud Lapin wrote:
On Oct 7, 5:54 pm, flightoffancy wrote: In article , says... The downwash thing is wrong. Yes, there is some dispacemtn of air that causes lift, but it' only a minor contribution in the bigger scheme of things. I admit to being a relative retard on this issue (not as retarded as a non-pilot probably is, but not as educated as an aeronautical engineer). I thought I had read in numerous books during training that the primary component of lift is the air that gets knocked downward by the wing. I was calling that "downwash". Maybe my concept of downwash is wrong, maybe it's a separate consideration from the air that gets knocked downward by the airfoil. Hell I might not be remembering any of that correctly. Just wanted to reiterate what I said in my OP and each subsequent post for you benefit since you just joined the discussion. If you have an aifoil, and you move it forward, there will be compression beneath the wing. Newton's law will be at play here, and there will be downwash. This downwash results from the induced pressure gradient. That is not what I was talking about. The books that I have been reading are talking about downwash that is _on top of_ the wing. The pictures show air moving at an angle, backward and downward near the trailing edge of the wing. Note that these are two "downwashes". I am saying that downwash on top of the wing does not generate a force on the wing that causes the wing to move upward. Anyway you say downwash is minor. Well okay. But then what are the major contributions that cause lift in the bigger scheme of things? -Le Chaud Lapin-- Hide quoted text - - Show quoted text - If the airflow on top of the wing doesn't contribute to lift, then how can we explain the phenomenon of the wing stalling? When the wing stalls, it is the airflow over the top of the wing that detaches from the curve of the wing and becomes turbulent. This causes a radical loss of lift. To me, this indicates that the airflow over the top of the wing plays an essential role in providing lift. I know the Bernoulli effect has been invoked historically to (at least partially) explain the lift produced by the top surface of a wing. I think another way to look at it is the Coanda effect ( http://en.wikipedia.org/wiki/Coand%C4%83_effect ). The airflow tends to follow the curve of the top of the wing, and is displaced downward. As long as the air flow follows the curve faithfully, you have good lift. When the airflow detaches in a stall, you lose most of your lift. This top surface lift is combined with the downward displacement of air by the bottom of the wing. The wing is essentially throwing air downward using both the top and bottom surfaces. This is why a curved wing is a better lift producer than a simple flat wing. The top surface curve helps contribute to the lift. Now, how does the wing feel the lift? It feels high pressure on its bottom surface, and it feels low pressure on its upper surface. It is pushed up from below, and sucked up from above. That is how the airplane experiences the effects of the downward displacement of air. Phil |
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