long wire antenna
in [Repair]
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From: stickyfox on 22 Mar 2010 01:11 I don't know what the original topic is, or tangential one for that matter.. but I do know a lot about airflow over wings. I can tell you that if two molecules are neighbors, and they take opposite paths above and below the wing, they do -not- wind up neighbors on the trailing edge. Look at this image: http://www.dinosaurtheory.com/wing_air_flow3.jpg The main source of lift for an airplane is in fact the propeller. The wing diverts some of the force of the air hitting it in an upward direction (lift), and some into an impeding force (drag). The wing (and every other surface) is only designed in an airfoil shape to make it more efficient. Whether the plane is moving through the air or the air around the plane is not important; it's a superposition thing. A small plane with a STOL (slow takeoff/landing) kit can hover, or even fly backwards, in a good stiff breeze. The pilot doesn't need to compensate for this at all (until he gets low enough for the terrain to interrupt the wind). This is a very poorly understood concept. I've heard engineering professors botching it up before. Hope this sheds some light on something. On Mar 22, 1:00 am, mm <NOPSAMmm2...(a)bigfoot.com> wrote: > On Tue, 9 Mar 2010 01:53:39 -0000, "Arfa Daily" > > > > <arfa.da...(a)ntlworld.com> wrote: > > >"Phil Allison" <phi...(a)tpg.com.au> wrote in message > >news:7vj3h1F7nuU1(a)mid.individual.net... > > >> "Arfa Daily" > > >>>> It's not unlike a wing. Almost any surface flat on the bottom and curved > >>>> on the top can produce lift. > > >>> So how come a symmetrical wing, such as might be found on a stunt plane, > >>> still flies, and most asymmetric wings fly quite happily upside down ? > >>> :-) > > >> ** I ask people who *think* they know how a plane flys that same Q. > > >> Stumps them all the time. > > >> Goes to show how simple explanations are often highly flawed. > > >> ..... Phil > > >I saw an interesting dissertation on this some time back, which put forward > >a much more complex but better believable theory as to how a wing flies. I > >don't really remember the details, but it relied heavily on the wing's angle > >of attack into the air, to produce the pressure differential, and hence > >lift. I seem to recall that it was the opposite way round from the > >'conventional' teaching of increased speed of the air over the top of the > >wing reducing the pressure, and that this theory had the attack angle > >causing compression under the wing, thereby increasing the pressure to > >produce lift. I do, however, remember it saying that air has no > >'intelligence', and just because two previously adjacent molecules became > >divided above and below the wing, there was nothing to say that they had to > >form back up in the same way as they left the back edge of the wing, which > >would require the air to move faster over the longer upper surface. I > > Wait a second. The air isn't really moving. It's the plane that is > moving and the air is pretty much standing still, except where the > propeller blows it around but I don't think that's the whole wing. > > So the molecules that were together before the plane got there are > still almost together after the wing slices through the air. > > >believe it did say that the air actually does travel faster over the curved > >face of the wing, and that the fact that it does, does produce a reduction > >in pressure. However, this reduction is small, and only contributes a very > >limited amount of lift, compared to the main mechanism that's at work. > > And what's the main mechanism? > > >Arfa |