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#91
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lift, wings, and Bernuolli
As the wing approaches, the air starts moving up, eagerly anticipating
the meeting. Called "upwash". Not disputing, just trying to learn... but... the way I see it (and I'm not an aeronautical engineer) .... why does the air start moving up? AFAIK, lifting fairies don't push the air around; that's not in their contract. The way I see it, the high pressure air below the wing causes air to be displaced out from below the wing, and some of that pushes out ahead of the wing, pusing the air in front of the wing up out of the way. So, before the wing itself meets the air, the air is in an upwashing state. Then the leading edge meets the upwashing air and gains some lift from momentum transfer... However, in front of the upwashing air, the air is undisturbed. This is the initial state of the air - upwashing is somehow caused by the wing's approach. When the wing passes through the air, the air is forced downward as it follows the wing's angle of attack, since it can't go through the wing. After the wing has passed, the downward moving air slows down (to a stop?) as it compresses the air below it, helping to create the upwash in front of the wing. In another scenario, what happens in a long ducted fan? The blades are just wings going round and round providing lift in the direction of the duct, the duct prevents wingtip vortices, and air gets sucked in one end and pushed out the other end. Is this not analogous to a wing "pushing air down"? Jose -- Money: what you need when you run out of brains. for Email, make the obvious change in the address. |
#92
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Very long boring technical discussion of Lift Faries adn Thrust Demons....(NASA)
In article . net, Richard Lamb
says... According to Shafer "Lift is caused by Lift Demons. These little, invisible demons hold on to the leading and trailing edges of the aircraft and lift it into the air by flapping their wings (so, in a reductionist sense, lift is actually caused by feathers). First honest thing I've read in this thread. Lift is caused by feathers is a known scientific fact and I can prove it . Take a 10 # Canada goose and it will fly very nicely. Now pluck all the feathers and then watch this now naked Goose do high speed taxi's with it's little naked wings flapping wildly. The Goose sans feathers cannot fly so the answer is obvious to those who take the time the think about it. The average goose has 2 pounds of feathers so therefore for every pound of feathers you can lift 5# of goose. Therefore I propose that we build a man carrying mechanical Goose to prove this phenomena. We can start small with say an Ultralight version with a gross weight of 600#. We would need only about 120 # of feathers. We will need to fund this all important project so I'll be accepting donations...cash only . Later well do a project on how speed is caused ,you'll be amazed how it works.A small clue is electromagnetic plasma pulses rectified by an alum pyramid shaped hat. Don't forget to send money ... Lift Faries?? Pure bunk!! It's feathers my boy feathers!! Count Clipper |
#93
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Very long boring technical discussion of Lift Faries adn Thrust Demons....(NASA)
"ChuckSlusarczyk" wrote ...
First honest thing I've read in this thread. Lift is caused by feathers is a known scientific fact and I can prove it . I hate to get involved in these "what causes lift" threads but this is nonsense. An ostrich after all, with all it's feathers, CAN'T FLY. I already stated a couple weeks ago that flight is magic. A well known fact. Such silliness as "feathers" and "lift demons" is just an attempt to avoid being burnt at the stake by the fearful masses. Rich |
#94
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Very long boring technical discussion of Lift Faries adn ThrustDemons....(NASA)
ChuckSlusarczyk wrote:
First honest thing I've read in this thread. Lift is caused by feathers is a known scientific fact and I can prove it . Take a 10 # Canada goose and it will fly very nicely. Now pluck all the feathers and then watch this now naked Goose do high speed taxi's with it's little naked wings flapping wildly. The Goose sans feathers cannot fly so the answer is obvious to those who take the time the think about it. The average goose has 2 pounds of feathers so therefore for every pound of feathers you can lift 5# of goose. Therefore I propose that we build a man carrying mechanical Goose to prove this phenomena. We can start small with say an Ultralight version with a gross weight of 600#. We would need only about 120 # of feathers. We will need to fund this all important project so I'll be accepting donations...cash only . Later well do a project on how speed is caused ,you'll be amazed how it works.A small clue is electromagnetic plasma pulses rectified by an alum pyramid shaped hat. Don't forget to send money ... Lift Faries?? Pure bunk!! It's feathers my boy feathers!! Count Clipper Have you been drinking muzzle loader again??? Tony |
#95
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Very long boring technical discussion of Lift Faries adn Thrust Demons....(NASA)
("ChuckSlusarczyk" wrote)
Therefore I propose that we build a man carrying mechanical Goose to prove this phenomena. So, after the test flight, how do you get down from your mechanical goose? Montblack Minnesota State Bird - The Common Loon |
#96
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lift, wings, and Bernuolli
upwashing is somehow caused by the wing's approach.
On one level you can say it's a consequence of the bound vortex around the wing. Not satisfying? I agree, but that's about as far as most aerodynamics books go in providing an intuitive answer. In another scenario, what happens in a long ducted fan? Is this not analogous to a wing "pushing air down"? You aren't the first to pose that question and it's a good one. Here are some things which are unsupported by anything that I've read: There is at least one dis-analogy (new word) that I can think of. With a wing, it creates a low pressure area and then is gone; whatever happens to that low pressure area is irrelevant. The air that rushes into it has no effect on the wing. A fan, however, creates a permanent low pressure area in front of the airplane, which creates a flow from front to back which doesn't exist for a wing. |
#97
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The Impossibility of Flying Heavy Aircraft Without Training
"Jim Macklin" wrote in message news:uX8Lf.104268$4l5.39451@dukeread05... It was sad and never should have been allowed to happen. Some people knew what was planned, many escaped, but the world was unwilling to stop Hitler. Hope we don't make the same error again. We are making the same error again. If you look at the political tactics used by the Nazis in their rise to power, some of them ring a bell in a recent presidential campaign. 1. Attendees at Nazi rally were carefully screened and only Nazi supporters were allowed in. Bush political speechs had a screened audience and only known Bush supporters were allowed to attend. 2. Hitler pointed at jews and gypsies as the source of all the problems in the world of the third reich. Bush points at "terrorists" 3. The Nazi party evaded the German Democratic constitution and evaded the law to protect citizens from jews and gypsies. Bush evades the law and eavesdrops on american citizens when the only reason to evade the law is to keep the courts from knowing who and how many people he is eavesdropping on and what he is doing with the information. 4. The Nazi propaganda minister proved the validity of the "big lie." If you lie blatantly enough and often enough and do so on all of the public media a significant portion of the population will believe the lie. Bush always tell the truth even when he contradicts himself. Right. Highflyer Highflight Aviation Services Pinckneyville Airport ( PJY ) ( don't call me guys. someone may be listening after this post! :-) |
#98
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lift, wings, and Bernuolli
"Greg Esres" wrote in message oups.com... An infinitely wide wing has no wingtips. You suggest it could not provide lift. Heck no. It just does so with no *net* downward momentum of air. In other words, the upward momentum ahead of the wing is equal to the downward momentum at the rear of the wing. Disagree. There is a *net* downward momentum of air. Otherwise there is no lift. However the downward momentum for any finite section of the infinite wing is infinitesimal. Note, however, that even though in Calculus 100 we assume that an infinitesimal is approximately equal to zero and can be ignored, it is only approximately to zero and only very very near zero. While zero times any number is still zero, almost zero times infinity is NOT zero. Ergo, the downwash is not zero either. I've read the "wingtip vortices provide lift" papers, I'm not proposing that. the wing causes downwash which provides lift (action-reaction) and =that= creates vortices. Infinite wings have no downwash, yet provide lift. By *definition*, downwash is caused by wingtip vortices. No. wingtip vortices are caused by downwash. Infinite wings don't have wingtip vortices because they don't have ends, not because they don't have downwash. Highflyer Highflight Aviation Services Pinckneyville Airport ( PJY ) |
#99
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Very long boring technical discussion of Lift Faries adn Thrust Demons....(NASA)
"Richard Isakson" wrote in
: "ChuckSlusarczyk" wrote ... First honest thing I've read in this thread. Lift is caused by feathers is a known scientific fact and I can prove it . I hate to get involved in these "what causes lift" threads but this is nonsense. An ostrich after all, with all it's feathers, CAN'T FLY. I already stated a couple weeks ago that flight is magic. A well known fact. Such silliness as "feathers" and "lift demons" is just an attempt to avoid being burnt at the stake by the fearful masses. Rich Ostriches just don't have enough feathers to fly. As demonstrated by the Canada Goose, one pound of feathers lifts five pounds. An average 250 pound ostrich needs 50 pounds of feathers to fly. |
#100
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The Impossibility of Flying Heavy Aircraft Without Training
On 2/22/2006 11:07 AM, Robert M. Gary wrote:
A local pilot at our airport who owns a small Cessna 210 went to Boeing 737 school a few years back. He was able to shoot approaches to mins and fly quite nicely without any heavy iron training outside of some books and manuals he picked up. Of course, the work gets harder when the instructor starts to simulate things failing. Airline pilots are grossly over paid 99% of the time and grossly under paid 1% of the time. As long as everything is working its pretty easy. Thank you, Robert. This is exactly the reason I chose these groups for my _original_ post. I have a couple of follow-up questions. The local pilot you mentioned was already _quite_ capable of flying a Cessna 210, before attempting a 737. Would someone with little or no flight experience be able to fly a 737, 747, or 757, and also make steep dives and sharp turns? Standard Boeing commercial aircraft have locks on the cockpit doors. How difficult would it be break one down? What are the chances that 8 trained pilots and co-pilots, with military backgrounds, could be physically overpowered by a few thugs with box-cutters? -- Closely Monitored, Immanuel Goldstein "It's just a god-damned piece of paper!" - US President speaking about the US Constitution, http://www.counterpunch.org/leupp12142005.html "Speaking the Truth in times of universal deceit is a revolutionary act." - Orwell |
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