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As a designer in aerospace for 30 years I can say without reservation that airplanes suck.
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Okay, I'll add a twist; As a wing moves through the atmosphere, it's obvious that air moves chordwise parallel to the direction of the wing's travel. What happens at the wing tip? What does that imply about the flow over the wing? By the way, the post above that claims the pressure difference between the upper and lower surfaces results in "vortexes" at the trailing edge that create the lift is wrong. Unfortunately, the connection between vortex theory as a means of modeling the flow, and the actual nature of the flow is poorly taught. http://www.ar15.com/media/viewFile.html?i=33191 View Quote The cookies on the FBD are particularly entertaining. |
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fast moving air has lower pressure than slow moving air. Air has to travel faster over the curved top surface of the airfoil (longer distance) so it can arrive at the same time as air moving under the flat lower surface of the airfoil. Higher pressure on the bottom pushes up on the lower pressure on top, creating lift. View Quote I can do the same thing with time in my time travel machine. You don't go fwd/backwards in time, you have to move the past/future closer to you. |
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Alright it's Russian so it will miss anyway! View Quote View All Quotes View All Quotes Not hardly, that's a US weapon, and one of its cool attributes is its precision on the target. |
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The fluid (air, water etc) has to flow farther around one side of an asymmetrical foil than it does around the other side.
For the fluid to meet up at the trailing edge, it has to go faster. The pressure is lower on the fast moving side than on the lower side. The pressure differential creates force from the slow high pressure side towards the fast low pressure side. How'd I do? |
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Boom. That's it in the simplest terms possible. View Quote View All Quotes View All Quotes Quoted:
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The upper curved surface is longer than the bottom flat one. The air particles moving over the top are moving faster than the ones on the bottom thus creating less pressure on top of the air foil and producing lift. That's it in the simplest terms possible. How do airplanes fly upside down then? |
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How do airplanes fly upside down then? View Quote View All Quotes View All Quotes Quoted:
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The upper curved surface is longer than the bottom flat one. The air particles moving over the top are moving faster than the ones on the bottom thus creating less pressure on top of the air foil and producing lift. That's it in the simplest terms possible. How do airplanes fly upside down then? Angle of attack, control surface deflection and thrust creates a vectored momentum? Like how a bullet travels but the bullet would have thrust and fins to keep it pointed in the right direction. |
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Quoted: Not hardly, that's a US weapon, and one of its cool attributes is its precision on the target. View Quote View All Quotes View All Quotes Quoted: Quoted: Alright it's Russian so it will miss anyway! Not hardly, that's a US weapon, and one of its cool attributes is its precision on the target. Plus, it makes waffles.
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What do you want them to be? Cookies or pizzas one day, yummie yummie hamburgers on another day, or biscuits made with kernals of corn in the dough and slathered with butter on yet another. View Quote View All Quotes View All Quotes Quoted:
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Okay, I'll add a twist; As a wing moves through the atmosphere, it's obvious that air moves chordwise parallel to the direction of the wing's travel. What happens at the wing tip? What does that imply about the flow over the wing? By the way, the post above that claims the pressure difference between the upper and lower surfaces results in "vortexes" at the trailing edge that create the lift is wrong. Unfortunately, the connection between vortex theory as a means of modeling the flow, and the actual nature of the flow is poorly taught. http://www.ar15.com/media/viewFile.html?i=33191 What the fuck are those things trailing off the empennage? Pizzas? Cookies? I'm hungry. But if I eat pizza and cookies, I'll need to get on the treadmill. That won't fly. What do you want them to be? Cookies or pizzas one day, yummie yummie hamburgers on another day, or biscuits made with kernals of corn in the dough and slathered with butter on yet another. Crap! It's a Rorschach test. I went into engineering to avoid all this touchy feely stuff. |
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As can be successfully predicted using potential flow theory, you can approximate one by spinning a cylinder an a transverse fluid flow
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I'll give the Common Core answer:
Because white people are racist. |
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Explain it GD. I'm curious to see how many of you are wrong... And no treadmills! View Quote Bernouli's principal.....look it up |
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like this: <a href="http://s252.photobucket.com/user/Joe49ae/media/wing_zpsbbad0523.jpg.html" target="_blank">http://i252.photobucket.com/albums/hh39/Joe49ae/wing_zpsbbad0523.jpg</a> View Quote |
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View Quote Not curved, wont work. |
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Airfoils change the m______ of the ___ flowing across the ______e. Get out of here with your knowledge and logic. You know that does not work here in GD. Pfft physics. Answer is the devil Magic, they went to Hogwarts.............. |
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Bernoulli's Principle is a huge reason of how they fly. There's also Newton's third law which plays a big role with angle of incidence and an increasing angle of attack. A few other reasons as well, but it's all magic and magnets. But either way, OP is not as smart as he's trying to lead us to believe.
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Not curved, wont work. HA! You're just jealous because I look so cool! |
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Bernoulli's Principle is a huge reason of how they fly. There's also Newton's third law which plays a big role with angle of incidence and an increasing angle of attack. A few other reasons as well, but it's all magic and magnets. But either way, OP is not as smart as he's trying to lead us to believe. View Quote I never claimed to be smart I was taught this incorrectly in grade skool, and for many years I struggled with the idea that it didn't take all forces into account, and that air molecules really had no reason to want to reunite at the end of some distance traveled with their other molecule buddies. It mind fucked me for a long time until I got off my ass and researched the real reason and and least gained a paltry understanding of what's really happening. I'm sure many others were taught incorrectly, and thought this would be a fun way to spread correct info and eat some popcorn. |
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To all the Bernoulli fans, how does that work with an ultralight or hang glider wing? They are about what, 0.1mm thick?
FWIW, back in highschool I took a physics class which had one long lesson on how airfoils work. As an example they used a kite, which is of course fully stalled all the time. |
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A column of air(earths atmosphere) is thicker at the bottom. (weighs less at the top, weighs more at the bottom, because gravity pulls air down) A wing (foil) moving forward forces air down underneath it, increasing the weight of the air on the bottom, compressing the air underneath making it weigh more, and pushing the wing up against the lower pressure above, and repeat add infinitum. Its like a straw, are you sucking the fluid up or is the created vacuum causing the weight of the air to push the fluid up. Six of one and seven of the other.
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The wings are constantly shoving air toward the ground. The air gets downward momentum from the wings, momentum change takes force. The opposing force holds up the plane.
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Define work. Not cross product of force and length.
Airfoils are just beams optimized for lowest drag . Airfoil lift is another thing all together. Using zero angle of attack drag coefficient principle, lift is just the vertical component of drag. For symmetrical foils, zero angle of attack generates zero lift. Now, using basic mechanics, the lift must be the integral of pressure differential and area. So somehow, the wing develops a pressure differential based on the angle of attack. It is a momentum effect. |
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Define work. Not cross product of force and length. Airfoils are just beams optimized for lowest drag . Airfoil lift is another thing all together. Using zero angle of attack drag coefficient principle, lift is just the vertical component of drag. For symmetrical foils, zero angle of attack generates zero lift. Now, using basic mechanics, the lift must be the integral of pressure differential and area. So somehow, the wing develops a pressure differential based on the angle of attack. It is a momentum effect. View Quote Never heard of it - care to explain? |
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Never heard of it - care to explain? View Quote Not the exact thing Keith_J was speaking of, but think of this: Your hand is a basic airfoil shape, palm is flat, fingers and back of hand bulge upward. We have all stuck our arms out of a car and made it go up and down like a wing. When held flat, you only felt the drag slightly pushing your hand backwards, and no lift, even though the air over your hand is going faster than air under your hand. When you turned your hand up or down, the change in angle of attack did two things: Pushed backward on your arm really hard (drag), and made your arm swing up or down (lift), depending on which way you angled it. Angle of Attack has more to do with flight than air pressure differences, the major part of pressure differences pertains to stall conditions, where the boundary layer separates from the top of the wing (very high pressure on bottom of wing, very low pressure on top of wing). At that point, there is no more lift, only drag, and since the airfoil isn't working as a wing, the control surfaces aren't working as control surfaces, either. The real answer is more complex, but lift is mostly pushing air down, which creates drag, at most basic, it's vector math, at most complicated, such as boundary layer, it's fluid dynamics. |
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If Bernoulli's Principle is the mechanism of action, how does ground effect exist?
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If Bernoulli's Principle is the mechanism of action, how does ground effect exist? View Quote A little of it is from compressibility but the majority of it (in the average aircraft without special wing tip treatments) is from the inability to fully develop wingtip vortices due to its proximity to the ground. |
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Not curved, wont work. The way it's sitting, it's making upforce. |
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A little of it is from compressibility but the majority of it (in the average aircraft without special wing tip treatments) is from the inability to fully develop wingtip vortices due to its proximity to the ground. View Quote View All Quotes View All Quotes Quoted:
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If Bernoulli's Principle is the mechanism of action, how does ground effect exist? A little of it is from compressibility but the majority of it (in the average aircraft without special wing tip treatments) is from the inability to fully develop wingtip vortices due to its proximity to the ground. Bernoulli assumes incompressible air flow. If that isn't true, it all goes out the window. (See the P38 Lighting) |
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Now that I'm in my hotel room for the night, it's my turn to tackle this question. ... View Quote Now think about all that; does it explain "how airfoils work", or "how airfoils are used"? I'll answer that, those are charts that describe the behavior of 2D airfoils in isolation, and not as part of a wing. They are a first step in the application of an airfoil that describe the tail end of "how they work" without understanding of the physical mechanisms. The hilarious part is that you didn't post a single plot of pressure distribution at any angle of attack over the section to support your argument. Describing the flow over an airfoil or wing is much more complicated that saying, "derp, it's pressure, duh". We have to look at the flow in forward of the leading edge, along the chord, and aft of the trailing edge of a 2D airfoil, and spanwise flow along a 3D wing, then modifications to the flow caused by leading edge or trailing edge devices or spoilers and drag brakes installed between the leading edge and trailing edge. No one will argue that their is a pressure distribution over airfoils, no matter whether they are thick or thin (those have definitions), have a practically zero thickness ratio (a sail, a paper airplane, single surface hang gliders and ultralights), camber or no camber. But for whatever reason, the momentum mechanism is never discussed in airfoils 101, and that is a mistake. The lift on a wing is caused by momentum and direction of the airflow spilling off the trailing edge. Picture two airplanes of equal weight, one with a short fat wing and one with a long narrow wing of equal area (we don't care about spanwise taper and so on at this point), flying at identical speeds. Now picture circles circumscribing each wing, consider their respective areas, and imagine the amount (the volume and mass) of the air flowing through each circle. It's obvious that the mass of air flowing through the larger circle is much greater (by the square of the span) than through the small circle around the short wing. The lift is the same (same airplane weight, same speed), so what is happening at the wings? Make a sketch, calculate the area in each circle, note how the diameter (span) squared influences the area. Now, since this is GD science and we're already well into tl;dr territory, we'll jump ahead a little; while operating these airplanes, we noticed that the drag of the longer wing is less than the short wing! Hmmm, interesting, eh? Think about this a second; the longer wing produces the same lift as the short wing with less drag, so it appears to be "working" less hard to produce that lift! Whilst investigating the reason for the lower drag of the long wing, we also noticed that we could break the drag down into two broad sources, one that appeared to be related only to the cross section geometry of the wing (corrected for Reynolds numbers for you pedantics), and another that appeared to be related to the creation of lift! We'll call that "induced drag", the drag caused by production of lift, and the part caused by the shape we'll call "profile drag" (for now). So, the long wing produces the same lift with less drag, and we notice that it influences a much greater volume of air passing by, so we look a little closer and we discover that the air flowing off the trailing edge of the long wing departs at an angle to the chord that is less than from the short wing. "Walla" , we realize the longer wing produces less drag to produce the same lift because it doesn't have to turn the air flow over an angle as great as the short wing. We also realize at this point that the momentum (direction, speed, and mass flow integrated over the span) of the air coming off the trailing edge of the wing equals the lift required to support the airplane. In the 2D world, we draw theoretical airfoils and then calculate theoretical chordwise speeds, pressure distributions, and behavior of the boundary layer. David Bernoulli's principle is merely the jumping in place, it's barely a good start to the problem but does serve as a simple explanation of the basic mechanism. Mostly. We also know that there is not a 2D airfoil in the universe that can develop lift! [Using the lift equation, the area is zero, so the lift has to be zero.) In the real world, we attempt to measure the behavior of 2D airfoils by testing short 3D wings in wind tunnels, and then correcting all the effects that cause error (3D airfoils, tunnel wall effects, Reynolds Number, Mach Number, compressibility, and a zillion other factors) to learn how well our 2D estimation methods match the real world as best we can measure. It's very important to understand the magnitude of the errors at this stage. Also in the real world, we build airplanes with 3D airfoils (wings) with characteristics adjusted to produce desired characteristics for the design flight regime. We're shocked when we learn how unimportant all those airfoil shapes we fretted about choosing for our light airplane design turn out to be when considering performance, and learn that damn near any airfoily looking cross section shape will work about as well as the next one as long as they are thick enough for adequate structure inside, and that the planform shape dominates the airplane's performance. (Sailplanes are a little more critical since we need to really squeeze the profile drag part of the equation, too.) What we've learned is that 2D airfoils are theoretical constructions that exhibit distributions of speed and pressure along their chords but produce zero lift. 3D airfoils, or wings, produce lift by directing the momentum of the air flow across the surface at an angle to the chord at the trailing edge to produce the force that lifts the airplane. The chordwise distribution of pressure is interesting, but as long as it is well behaved it's pretty much of secondary interest if the airfoil is remotely suitable for the design flight mission. In the 3D world, we are at least as interested in the spanwise flow of air and how it behaves at the wing-fuselage intersection and at the tips. When discussing "airfoils" it is critical to be clear about whether the airfoil is 2D or 3D. |
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Now think about all that; does it explain "how airfoils work", or "how airfoils are used"? I'll answer that, those are charts that describe the behavior of 2D airfoils in isolation, and not as part of a wing. They are a first step in the application of an airfoil that describe the tail end of "how they work" without understanding of the physical mechanisms. The hilarious part is that you didn't post a single plot of pressure distribution at any angle of attack over the section to support your argument. Describing the flow over an airfoil or wing is much more complicated that saying, "derp, it's pressure, duh". We have to look at the flow in forward of the leading edge, along the chord, and aft of the trailing edge of a 2D airfoil, and spanwise flow along a 3D wing, then modifications to the flow caused by leading edge or trailing edge devices or spoilers and drag brakes installed between the leading edge and trailing edge. No one will argue that their is a pressure distribution over airfoils, no matter whether they are thick or thin (those have definitions), have a practically zero thickness ratio (a sail, a paper airplane, single surface hang gliders and ultralights), camber or no camber. But for whatever reason, the momentum mechanism is never discussed in airfoils 101, and that is a mistake. The lift on a wing is caused by momentum and direction of the airflow spilling off the trailing edge. Picture two airplanes of equal weight, one with a short fat wing and one with a long narrow wing of equal area (we don't care about spanwise taper and so on at this point), flying at identical speeds. Now picture circles circumscribing each wing, consider their respective areas, and imagine the amount (the volume and mass) of the air flowing through each circle. It's obvious that the mass of air flowing through the larger circle is much greater (by the square of the span) than through the small circle around the short wing. The lift is the same (same airplane weight, same speed), so what is happening at the wings? Make a sketch, calculate the area in each circle, note how the diameter (span) squared influences the area. Now, since this is GD science and we're already well into tl;dr territory, we'll jump ahead a little; while operating these airplanes, we noticed that the drag of the longer wing is less than the short wing! Hmmm, interesting, eh? Think about this a second; the longer wing produces the same lift as the short wing with less drag, so it appears to be "working" less hard to produce that lift! Whilst investigating the reason for the lower drag of the long wing, we also noticed that we could break the drag down into two broad sources, one that appeared to be related only to the cross section geometry of the wing (corrected for Reynolds numbers for you pedantics), and another that appeared to be related to the creation of lift! We'll call that "induced drag", the drag caused by production of lift, and the part caused by the shape we'll call "profile drag" (for now). So, the long wing produces the same lift with less drag, and we notice that it influences a much greater volume of air passing by, so we look a little closer and we discover that the air flowing off the trailing edge of the long wing departs at an angle to the chord that is less than from the short wing. "Walla" , we realize the longer wing produces less drag to produce the same lift because it doesn't have to turn the air flow over an angle as great as the short wing. We also realize at this point that the momentum (direction, speed, and mass flow integrated over the span) of the air coming off the trailing edge of the wing equals the lift required to support the airplane. In the 2D world, we draw theoretical airfoils and then calculate theoretical chordwise speeds, pressure distributions, and behavior of the boundary layer. David Bernoulli's principle is merely the jumping in place, it's barely a good start to the problem but does serve as a simple explanation of the basic mechanism. Mostly. We also know that there is not a 2D airfoil in the universe that can develop lift! [Using the lift equation, the area is zero, so the lift has to be zero.) In the real world, we attempt to measure the behavior of 2D airfoils by testing short 3D wings in wind tunnels, and then correcting all the effects that cause error (3D airfoils, tunnel wall effects, Reynolds Number, Mach Number, compressibility, and a zillion other factors) to learn how well our 2D estimation methods match the real world as best we can measure. It's very important to understand the magnitude of the errors at this stage. Also in the real world, we build airplanes with 3D airfoils (wings) with characteristics adjusted to produce desired characteristics for the design flight regime. We're shocked when we learn how unimportant all those airfoil shapes we fretted about choosing for our light airplane design turn out to be when considering performance, and learn that damn near any airfoily looking cross section shape will work about as well as the next one as long as they are thick enough for adequate structure inside, and that the planform shape dominates the airplane's performance. (Sailplanes are a little more critical since we need to really squeeze the profile drag part of the equation, too.) What we've learned is that 2D airfoils are theoretical constructions that exhibit distributions of speed and pressure along their chords but produce zero lift. 3D airfoils, or wings, produce lift by directing the momentum of the air flow across the surface at an angle to the chord at the trailing edge to produce the force that lifts the airplane. The chordwise distribution of pressure is interesting, but as long as it is well behaved it's pretty much of secondary interest if the airfoil is remotely suitable for the design flight mission. In the 3D world, we are at least as interested in the spanwise flow of air and how it behaves at the wing-fuselage intersection and at the tips. When discussing "airfoils" it is critical to be clear about whether the airfoil is 2D or 3D. View Quote View All Quotes View All Quotes Quoted:
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Now that I'm in my hotel room for the night, it's my turn to tackle this question. ... Now think about all that; does it explain "how airfoils work", or "how airfoils are used"? I'll answer that, those are charts that describe the behavior of 2D airfoils in isolation, and not as part of a wing. They are a first step in the application of an airfoil that describe the tail end of "how they work" without understanding of the physical mechanisms. The hilarious part is that you didn't post a single plot of pressure distribution at any angle of attack over the section to support your argument. Describing the flow over an airfoil or wing is much more complicated that saying, "derp, it's pressure, duh". We have to look at the flow in forward of the leading edge, along the chord, and aft of the trailing edge of a 2D airfoil, and spanwise flow along a 3D wing, then modifications to the flow caused by leading edge or trailing edge devices or spoilers and drag brakes installed between the leading edge and trailing edge. No one will argue that their is a pressure distribution over airfoils, no matter whether they are thick or thin (those have definitions), have a practically zero thickness ratio (a sail, a paper airplane, single surface hang gliders and ultralights), camber or no camber. But for whatever reason, the momentum mechanism is never discussed in airfoils 101, and that is a mistake. The lift on a wing is caused by momentum and direction of the airflow spilling off the trailing edge. Picture two airplanes of equal weight, one with a short fat wing and one with a long narrow wing of equal area (we don't care about spanwise taper and so on at this point), flying at identical speeds. Now picture circles circumscribing each wing, consider their respective areas, and imagine the amount (the volume and mass) of the air flowing through each circle. It's obvious that the mass of air flowing through the larger circle is much greater (by the square of the span) than through the small circle around the short wing. The lift is the same (same airplane weight, same speed), so what is happening at the wings? Make a sketch, calculate the area in each circle, note how the diameter (span) squared influences the area. Now, since this is GD science and we're already well into tl;dr territory, we'll jump ahead a little; while operating these airplanes, we noticed that the drag of the longer wing is less than the short wing! Hmmm, interesting, eh? Think about this a second; the longer wing produces the same lift as the short wing with less drag, so it appears to be "working" less hard to produce that lift! Whilst investigating the reason for the lower drag of the long wing, we also noticed that we could break the drag down into two broad sources, one that appeared to be related only to the cross section geometry of the wing (corrected for Reynolds numbers for you pedantics), and another that appeared to be related to the creation of lift! We'll call that "induced drag", the drag caused by production of lift, and the part caused by the shape we'll call "profile drag" (for now). So, the long wing produces the same lift with less drag, and we notice that it influences a much greater volume of air passing by, so we look a little closer and we discover that the air flowing off the trailing edge of the long wing departs at an angle to the chord that is less than from the short wing. "Walla" , we realize the longer wing produces less drag to produce the same lift because it doesn't have to turn the air flow over an angle as great as the short wing. We also realize at this point that the momentum (direction, speed, and mass flow integrated over the span) of the air coming off the trailing edge of the wing equals the lift required to support the airplane. In the 2D world, we draw theoretical airfoils and then calculate theoretical chordwise speeds, pressure distributions, and behavior of the boundary layer. David Bernoulli's principle is merely the jumping in place, it's barely a good start to the problem but does serve as a simple explanation of the basic mechanism. Mostly. We also know that there is not a 2D airfoil in the universe that can develop lift! [Using the lift equation, the area is zero, so the lift has to be zero.) In the real world, we attempt to measure the behavior of 2D airfoils by testing short 3D wings in wind tunnels, and then correcting all the effects that cause error (3D airfoils, tunnel wall effects, Reynolds Number, Mach Number, compressibility, and a zillion other factors) to learn how well our 2D estimation methods match the real world as best we can measure. It's very important to understand the magnitude of the errors at this stage. Also in the real world, we build airplanes with 3D airfoils (wings) with characteristics adjusted to produce desired characteristics for the design flight regime. We're shocked when we learn how unimportant all those airfoil shapes we fretted about choosing for our light airplane design turn out to be when considering performance, and learn that damn near any airfoily looking cross section shape will work about as well as the next one as long as they are thick enough for adequate structure inside, and that the planform shape dominates the airplane's performance. (Sailplanes are a little more critical since we need to really squeeze the profile drag part of the equation, too.) What we've learned is that 2D airfoils are theoretical constructions that exhibit distributions of speed and pressure along their chords but produce zero lift. 3D airfoils, or wings, produce lift by directing the momentum of the air flow across the surface at an angle to the chord at the trailing edge to produce the force that lifts the airplane. The chordwise distribution of pressure is interesting, but as long as it is well behaved it's pretty much of secondary interest if the airfoil is remotely suitable for the design flight mission. In the 3D world, we are at least as interested in the spanwise flow of air and how it behaves at the wing-fuselage intersection and at the tips. When discussing "airfoils" it is critical to be clear about whether the airfoil is 2D or 3D. I don't disagree with any of that. That is an awesome explanation. I also don't see how your explanation refutes my use of the sectional lift coefficient graphs. They were merely being used to illustrate the real effect of Bernoulli's law. What, specifically, about my post do you take issue with? Do you disagree with my statement that airfoils produce lift even at zero angle of attack? Or is it my differentiating between Bernoulli's and Newton's methods of generating lift that you take issue? I do tend to see the two as being distinguishable but when combined the net affect being just what you described; a downward momentum of airflow off the trailing edge of the wing. Tell me this, (this will help to clarify the concept for me); can a cambered wing produce some measurable degree of lift at 0 or even slightly negative angles of attack with no measurable downward momentum off the trailing edge of the wing? What I'm in envisioning is the airs momentum coming directly off the trailing edge of the wing, aligned with the chord, but still producing some small degree of lift concentrated around the first third of the chord. I would have thought this entirely possible in certain circumstances, but perhaps I'm wrong on that point. Seriously though, tell me everything about my post you think is incorrect as this knowledge stands a good chance of being useful to me in some technical interview somewhere. |
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Your ideas are incomplete. Separate purely 2D from 3D behavior, it's that simple.
A 2D airfoil is a theoretical construct, and when incorporated into a 3D wing, the characteristics are significantly different; the lift curve slope changes, the maximum lift, moment, and drag coefficients all change, and not to the better. The main purpose of testing short wings with either significant end plates or intersecting the tunnel walls is an attempt to produce a "semi infinite" span wing to approach 2D characteristics. You'll also find that increasing aspect ratio of real wings tends to cause the airfoil characteristics to approach the 2D ideal. Naturally, tapering the wing introduces another detail that modifies the airfoil behavior by reducing the Reynolds Number toward the wing tips. I didn't see a single comment in this thread about the (incorrect) momentum transfer theory, i.e., Newtonian theory, of the airflow impacting on the lower surface of an airfoil (wing) to produce lift until you brought it up. I made no comment about camber and lift at zero angle of attack because it was not necessary. I already stated that the "Bernoulli effect" is a simplification to help understand why the pressure changes over a curved surface, but it's just a place to start. |
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