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#81
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Stop replying to this idiot.
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#82
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If a (compressible) fluid flows from a fat tube into a thin tube and
back into a fat tube, it is being "squeezed into a smaller area" when it's in the thin tube. The Bernoulli equation only applies to *incompressible* flow. This is required by the way the trailing edge of the wing is angled. What about reflexed airfoils? |
#83
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TRUTH wrote:
Dan wrote in news:T3kLf.23569$Ug4.20610@dukeread12: TRUTH wrote: Dan wrote in news:qDhLf.22857$Ug4.13336@dukeread12: TRUTH wrote: Dan wrote in news:ICaLf.19925$Ug4.16290@dukeread12: Richard Lamb wrote: "How does a wing generate lift?" Actually they don't. Aircraft only fly because everyone believes they do. Once enough people start doubting they will cease to do so. This is my conspiracy theory and I'm sticking to it. Dan, U.S. Air Force, retired Dan, what do you thing of Dr Robert Bowman? He's a retired USAF Lt. Col. and Nasa rocket scientist. He says if NORAD were left alone to do their job, all four planes would have been intercepted. He can be seen in this video, about halfway through: http://www.911busters.com/DC_Truth/index.html Bowman is also running for Congress http://www.rmbowman.com/ As an engineering type he would have had very limited experience with the operational side of the USAF. On the other hand I was on the operational side and I highly doubt a) anyone tied NORAD's hands were tied, b)that NORAD was looking for attacking flights within CONUS, they tend to look outward for that, c) that alert aircraft would have located them and had been able to receive orders to shoot them down in time to stop all 3 strikes. Let's face it, not too many people would have believed what was about to occur ever would. In any event aircraft go astray every single day, should there be a military response to all of them? Aircraft sitting alert are thoroughly preflighted. This process takes 2 or 3 hours. I have seen helicopters and C-130s preflighted and ready to go in less than an hour, but those were emergency medevac situations not involving arming the aircraft. On weekends and holidays it was harder to gen up aircrews than aircraft. On normal duty days such as 9-11 you would have had problems genning up aircrews due to training, crew rest, additional duties etc. Could any of the aircraft been intercepted? Possibly, but what action would be taken? Could all 4 have been intercepted? Highly unlikely. Dan, U.S. Air Force, retired Before 9/11 how many times a year (approx) did NORAD scramble jets? NORAD never did, they don't own any jets. BTW, did you ever notice how military aircraft sent to check out wayward aircraft before or since 9/11 tend to make the news? Back to your attempt at misdirection let's do a hypothetical and assume NORAD requests a dozen interceptions in 2000. Every one would have been to chase a single aircraft. 9/11 had 4 errant airplanes. What difference does how many intercepts were called for before or since? I'll answer that for you: it makes no difference at all. Dan, U.S. Air Force, retired According to CBS news, NORAD scrambled jets 57 times the year before 9/11. Why didn't the FAA call NORAD to scramble jets after the first plane "hijacked"? Why did they wait for the third to be hijacked? FAA has no authority over NORAD. Maybe FAA hadn't been too worried before then. I have never had scrambled jets, do they taste anything like scrambled eggs? Dan, U.S. Air Force, retired |
#84
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"Gig 601XL Builder" wrDOTgiaconaATcox.net wrote in news:11vrmij7iu3hkf9
@news.supernews.com: Stop replying to this idiot. I try not to, but the Gig 601XL Builder keeps posting over and over. What a brainwashed lowlife he is ha ha ha |
#85
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The Bernoulli equation only applies to *incompressible* flow.
Right. But the Bernoulli principle applies to compressible and incompressible flow. It is the source of the venturi effect, which occurs in air, among other places. What about reflexed airfoils? I am not familiar with them. The trailing edge is depicted as pointing up; does it do so when the wing is at a lifting angle of attack? Is there an airflow separation near the trailing edge? If air is not being deflected downwards somewhere, we're back to the lifting fairies. ![]() Jose -- Money: what you need when you run out of brains. for Email, make the obvious change in the address. |
#86
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But the Bernoulli principle applies to compressible and
incompressible flow. True. But your original text suggested that the fluid *had* to be compressible. The trailing edge is depicted as pointing up; does it do so when the wing is at a lifting angle of attack? Good question. I don't know. Anyway, remember that there is no overall downward movement of the air unless there exist wingtip vortices. This suggests that the important downward momentum of air happens *after* the air leaves the trailing edge. I'm not certain that what direction the trailing edge is actually pointing is critical. I'm skeptical that if you have an airfoil generating positive lift, just tilting the trailing edge upwards slightly is going to kill that lift. Also, although theory (Kutta Condition) says that the air flow leaves the trailing edge smoothly, my understanding is that in real life, the rear stagnation point will be somewhat on the top surface of the airfoil anyway. |
#87
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On 2/22/2006 1:09 PM, Jim Macklin wrote:
Schumer would have been a trustee guard in a Nazi camp. Speaking of camps, Americans shall be herded into their very own camps in the not so far future. Provided by your very own FEMA. By the way, any Americans still remember when FEMA suddenly appeared out of thin air, in 1992, after the Hurricane Andrew disaster hit Florida? Many, many, unanswered questions by the media _that_ day. LOL! For what it's worth, the present FEMA has secretly existed since 1979, but the original FEMA existed long before Carter. http://www.sonic.net/sentinel/gvcon6.html -- Closely Monitored, Immanuel Goldstein "The history of the present [Government] is a history of repeated injuries and usurpations, all having in direct object the establishment of an absolute Tyranny over these States. To prove this, let facts be submitted to a candid world." - Declaration of Independence The Pentagon Strike http://www.pentagonstrike.co.uk/flash.htm The Demolition of Building 7 http://911research.com/wtc/evidence/videos/index.html#building7 "It's just a god-damned piece of paper!" - US President speaking about the U.S. Constitution, http://www.counterpunch.org/leupp12142005.html "Speaking the Truth in times of universal deceit is a revolutionary act." - Orwell "But when a long train of abuses and usurpations, pursuing invariably the same Object evinces a design to reduce them under absolute Despotism, it is their right, it is their duty, to throw off such Government, and to provide new Guards for their future security." - Declaration of Independence |
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But your original text suggested that the fluid *had* to be
compressible. Yes, it did suggest that. It shouldn't have. My clumsiness. Anyway, remember that there is no overall downward movement of the air unless there exist wingtip vortices. An infinitely wide wing has no wingtips. You suggest it could not provide lift. I've read the "wingtip vortices provide lift" papers, I'm not convinced that the correlation implies a causation in that direction. I see it as: the wing causes downwash which provides lift (action-reaction) and =that= creates vortices. The higher pressure air underneath the wing has to go somewhere - around (the wingtip) and up makes sense to me, and that is a vortex. What happens in the two-dimensional case? I'm skeptical that if you have an airfoil generating positive lift, just tilting the trailing edge upwards slightly is going to kill that lift. I agree with you. The downward movement of air is being generated over the entire wing chord, and has some depth to it too. I suspect (without solving any equations) that tilting the trailing edge upwards slightly (that's what ailerons do, sort of) does reduce lift, but as the airflow right underneath the airfoil gets deflected upwards, the air further away (below) does not, leaving a small lower pressure region just below the upward pointing trailing edge. The rest of the mass of air below this small low pressure region continues downwards through its momentum. Jose -- Money: what you need when you run out of brains. for Email, make the obvious change in the address. |
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Tim Ward wrote:
All those theories have been discredited anyway. It's invisible magic lift fairies that do all the real work. Tim Ward Mary Schaefer's (NASA) "Lift Demons" and "Drag Demons" ... The Role of Lift Demons and Thrust Pixies in Heavier Than Air Flight Publication Date: April 2005 Abstract: The role of Lift Demons in aeronautics was first explained in 1994 by Mary Shafer (NASA). Since then, Shafer's work has been explored and revised. This paper summarises advances in Lift Demon technology over the last decade. Keywords: Lift Demons, Thrust Pixies, lemon fondant Question: How did the secret information on Lift Demons make it into the public domain? I've been a practising Aircraft Performance Engineer for the past 26 years and have always tried to explain how aeroplanes fly by using the official public explanations regarding Bernoulli, airfoils and other such rot. Civilians just weren't ready for the truth. In fact, we generally don't speak about the magic directly. Most of our plans and estimates usually end with the phrase "and then a miracle happens". Answer: The science of Lift Demons was declassified in 1994, throwing this topic wide open for discussion and research. 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). Some of the demons are a little confused and they hold on backwards, causing drag. The reason that planes stall at high alpha is that the leading edge demons get scared and let go when they can't see the ground anymore. Lift demons have good taste and don't like to look at ugly aircraft, so they hold on backwards on ugly planes. That's why gliders have so much lift and so little drag and why F-4s have lots of drag." This, however, did not address what gives lift to the Lift Demons' wings. Again, according to Shafer "Feathers. The multiple filaments on feathers trap the air molecules and they struggle to escape, which causes the action-reaction that we call lift. Bat wings don't have feathers but they're hairy and that works just about as well (air molecules are a little claustrophobic)." It was originally believed that Lift Demons got their lift from smaller Lift Demons whose lift was, in turn, produced by even smaller Lift Demons leading to the "Infinite Demons Theory" as proposed by the great Greek philosopher-scientist Miasma. However, with the revival of scientific knowledge that eventually ended the Dark Ages, it was realised that this situation unresolvable according to Zeno's paradox. The "Infinite Demons Theory" works in many problems of engineering significance, however, real understanding requires that the ether be introduced into the analysis at some point. The "Ether Concept" explains why planes fly more efficiently at higher altitudes. This is an absolute necessity when studying orbital and interplanetary travel where, it is believed, many of the Lift Demons are unable to breathe. As always the Chinese seem to have been there first. "The Genius of China", tells of one Ko Hung. "Someone asked the Master (Ko Hung) about the principles of mounting to dangerous heights and travelling into the vast inane. The Master said "[...] some have made flying cars with wood from the inner part of the jujube tree, using ox leather straps fastened to returning blades so as to set the machine in motion. Others have the idea of making five snakes, six dragons and three oxen to meet the 'hard wind' and ride on it, not stopping until they have risen to a height of 40 li (about 65,000 feet). The the ch'i [emanation of the sky or perhaps wind] is extremely hard, so much so that it can overcome the strength of human beings. [...] Take dragons, for example; when they first rise they go up using the clouds as steps, and after they attained a height of forty li then they rush forward effortlessly gliding." The jujube tree device sounds like the Osprey. Scholars believe that the term "dragon" referred to the Lift Demon and that the Chinese had harnessed their power before the Western world had even discovered the Lift Demons' existence. Lift Demons operate differently on different aircraft types. They get dizzy holding onto a spinning prop and become disorientated, thus more of them face the wrong direction which increases the drag. Lift Demons have to be magically bound to jet engines and an Airbus propulsion engineer explained "It takes an average of three day's solid chanting and ritual to get one of those 'engine' things to work. If us witches stopped our hard work, there'd be planes dropping out of the sky all over the place. We should never have let you lot find out about being able to fly, it's been nothing but trouble ever since." Recognition of Lift Demons has also solved one of aviation's oldest puzzles: Gremlins. There appears to be a connection between Gremlins and Lift Demons. Gremlins may be Lift Demons that have, in some way, turned against the pilot. Instead of assisting him in his task of keeping the machine in the air, they do the opposite. The reason may be that, after reading about the Bernoulli/Newton dichotomy, they have become confused. Much has been written about Gremlins, dating back to WWII. Gremlins have been known to run towards the nose of an aircraft, causing it to dive into the sea, showing that they have at least some knowledge of the principles of flight. These days, most planes carry a full complement of In-Flight Gremlins; although they must be carefully managed, their presence generally inhibits the transformation of rogue Lift Demons into Gremlins. Further study of Lift Demons was carried out by an aero-industry weights engineer who submitted the following scientific paper in 2004 to celebrate the anniversary of Shafer's ground-breaking article: "There are still people in this company who think we weigh aircraft to find out how much they weigh, not to calculate stresses. Of course we need to know how much the thing weighs. How are we ever going to know how many Thrust Pixies we need to get the thing off the ground if we don't know the weight? Or should that be "Lift Demons"? Pixies have largely fallen into disrepute - something about Bernoulli not being representative in unbounded conditions and cause and effect being transposed in the Newtonian model. In fact the use of Lift Demons on civil aircraft programmes is generally not that good an idea. The Demon binding contract tends to specify payment in blood or souls. This is readily achievable with aircraft of military function, but frowned upon in civilian circles as they may attempt to acquire payment outside of the terms of their binding contract. Lift Demons are not used on Elf bombers. We don't talk about Lift [Thrust] Pixies too often as it seems to upset the self-loading cargo [passengers]. Pixies require payment in cakes, flowers or nice thoughts. These are readily sourced either from the in-flight catering, or provided cost-free by the passengers. Clearly this would not work well within an operational military environment. Air force cooking is not renowned for the "light and fluffy texture" that Thrust Pixies demand, the availability of flowers might be problematic in desert operations, and nice thoughts may also be hard to find during times of active operations. There is also a scalability issue. While one rampant Lift Demon would have few problems supporting a fighter aircraft (particularly if there is an immediate prospect of blood), it'll struggle to achieve level controlled flight of a 560 tonne Airbus A380. Use of more than one Lift Demon on the same flight vehicle is contra-indicated (they squabble and eat each other). Communities of Thrust Pixies can be encouraged to work together on the same aircraft by the provision of advanced technologies such as Lemon fondant icing, variegated tulips or in-flight romantic comedies. Ryanair once requested Leprachauns be installed in place of Lift [Thrust] Pixies, but Leprechauns have a mission statement which indicates their desire for monetary gain, and their willingness to search all over the world for it. This makes Lift Leprechauns expensive to keep (gold vs. lemon fondant icing), and makes it difficult to establish a regular route network as the Lift Leprechauns don't like to continuously visit the same locations. By law, aircraft also have to have a full complement of In-Flight Gremlins, but these are generally not a problem unless you feed the Wingtip Vortex Faeries after midnight." His article shows that we've moved on a great deal since 1994. It has been known for some time that Lift Demons are best suited to military uses. In spite of suggestions that Pixies have fallen into disrepute, outside of military aviation it is Lift Demons that are considered passé - they have notoriously short attention spans and the ones used on Harriers have problems discriminating between air and water. Inbreeding in pursuit of the ultimate high performance Lift Demon may have been the cause. In civil aviation, the way ahead still lies with Thrust Pixies, large amounts of lemon fondant icing and in-flight Hugh Grant movies. Many instances of civil planes mysteriously falling out of the sky can be traced to (a) cessation of happy thoughts/lack of lemon fondant for the pixies (resulting in "Pixie Fatigue" or even "catastrophic pixie failure") or to (b) a large amount of happy thoughts/gateau mountain at ground level distracting the pixies from their task. Thrust Pixies dislike Marmite/Vegemite (yeast extract) and since such spreads can cause unhappy thoughts in some passengers, airline caterers are careful to avoid these. A note on Catastrophic Pixie Failu Temporary pixie problems resulting in turbulence or sudden loss of altitude causes unhappy thoughts in the passengers (which is why cabin staff and pilots alway play down such occurrences). The resulting loss of happy thoughts causes further Pixie failure, worsening the situation. This makes passengers have even more unhappy thoughts and the Pixies become more fatigued; some may even leave the aircraft. Unless counter-acted by large lemon fondant reserves, Pixie Failure reaches catastrophic proportions and the aircraft is doomed. Modern aircraft designers use Lift Fairies and avoid the whole controversy regarding the used of Lift Demons on civil aircraft programmes. Coming from a less benevolent cast, Lift Fairies are less dependent on nice thoughts or cakes. Fairies tend to less concerned with good and evil and hence make better dual use aircraft. Another major headache today is how to get 707 Lift Fairies at a reasonable price. Many of the older aircraft-specific fairies have become rare, if not unavailable. Aircraft numbering relates to the type and quantity of Lift Demons or Lift Fairies needed. For example a C-130 requires 130 "C class" Lift Demons while an Airbus A380 uses 380 "A" class Thrust Pixies. Aero engineers have a scale of values (proprietary information, not available in the public domain) allowing them to substitute different numbers of Pixies and Demons with different lifting abilities, thus making best use of the available surfaces. There was short-lived interest in breeding a generic, or at least dual-use, "Thrust Demon" but the blood-loving Lift Demons ate the gateau-loving Thrust Pixies. In vitro techniques failed because their genietic [sic] material is incompatible so there are no hybrid Thrust Demons. DNA sequencing has allowed us to distinguish between many castes of Lift Demon, Thrust Fairy etc. For example due credit should be given to the inelegantly named Fart Fairies without whose bean eating and gas production, no machine could power itself from the earth's surface. The shy Turbine Winder-Rounder Gnomes hide inside those so-called engine nacelles from the public and indulge their serious kerosene drinking problems. Why else would the engines be called Gnome engines? Leading-Edge Leeries give the extra little push that keeps the nose up. The unfortunate tendency for RAF Harriers to crash into the sea has led to speculation that Harriers are equipped with Sirens or that the crashes resulted from an ill-advised experiment in using Water Nymphs (these are better suited to submarine propulsion). In any case, only export versions of the Harrier are likely to use Sirens, while those for the British domestic market use Banshees leased from the Irish. Thrust Pixies are adequate for civil aircraft, while Lift Demons were good in military applications in years past, but modern Naval Aviation is currently all Angel-powered. The very best ones are, of course, Blue Angels. This is why they report their altitude as "angels twenty" or such. In addition, many Navy pilots claim that black air has no lift, which means they can get all night in to supplement their daytime naps between meals. This shows that Angels and Naval Lift Demons are strictly diurnal. Genetically engineered, military-tolerant Thrust Pixies may be what is needed. Thrust Demons might also have applications in getting Air Force maritime patrol aircraft to stop reaching "prudent limit of endurance" by 2 p.m. (local time) every Friday just after reporting a "possible intruder" submarine in the exercise area, and not be restored to flying status until 9 a.m. Monday, thus leaving the ships to stay out over the weekend looking for the "intruder". There are no Anti-Gravity Demons so a different approach has to be taken in this field of research. Current research into inertia-free propulsion has shown great promise through the use of properly modified felines. Butter is spread evenly over the felines back. When the creature is tossed lightly into the air, the third law of universal fate dictates that it must land butter side down. However this does not occur due to the intervention of the feline landing axiom (feet first). The above conflicting forces result in a stable hover. The subject felines have demonstrated the ability to control their own velocity at will. The only loose ends delaying the full commercialisation of this process is the matter of persuading the felines to (a) work in teams; (b) not lick off the butter and (c) follow a flight plan. As there seems to be a deficiency in feline herding instincts, any suggestions would be appreciated by the researchers involved. |
#90
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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. 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. The higher pressure air underneath the wing has to go somewhere - around (the wingtip) and up makes sense to me, and that is a vortex. Except when you don't have wingtips. ;-) |
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