@@badgyro1 I'm pretty sure that someone working on the aerodynamics for a fighter aircraft actually understands how airfoils work and concepts like circulation, downwash, the Kutta condition, and has at least a rough understanding of the Navier Stokes equations.
So are you complaining about the simplification? Or do you not feel that there is a pressure differential between the upper and lower surfaces of an airfoil caused by the Bernoulli effect that accounts for a large percentage of lift? What exactly is the "nonsense"?
@@badgyro1 One could argue that pilots do not need to know what causes lift. And, it would be hard to refute that argument given how many successful pilots don’t have a real clue. You will see lots of explanations (like in this video) that start out talking about airfoils having curved tops or looking like a cross section of a venturi. You will also hear pilots claiming that it’s Bernoulli on the top and Newton on the bottom (generally having something to do with flats and curves). But those ideas are simply not true. An airfoil does not need to (and in many cases does not) look like a cross section of a venturi to generate lift. An airfoil does not need to have a curved top at all. Now, there are practical reasons that airfoils tend to be curved on top - introducing camber allows higher coefficients of lift and you need room for structure, but a curve is not a fundamental property of an airfoil. And clearly, a curve is not required for lift. Examples of successful flat airfoils would be paper airplanes and those cheap balsa gliders. It should be clear that they fly just fine and generate lift without a trace of a curve. So it should be equally clear that any “explanation” or “simplification” of how an airfoil works by introducing curves or cross sections of a venturi is “Soooooo nonsense”. I will agree that it takes some effort to present an anatomically correct simplification of how a wing generates lift. If you try to introduce the concept of circulation - game over - pilots will just fade out when you get into vector algebra (in spite of the fact that this is how the back of an E6-B works). You can talk about downwash - but how does that get back to generating an actual force on the wing to hold the airplane up? Yea, more math. O.M.G. Ask an instructor if some pilots struggle with math that is as basic as weight and balance. Now, as far as the pressure difference between the top and bottom of a wing that keeps airplanes in the air is concerned, for subsonic flow all of it can be calculated using Bernoulli’s equations (basically the tradeoff between kinetic and potential energy applied to an ideal fluid) (given the assumptions behind the equations) - flow is faster over the top (higher kinetic energy, lower pressure (less potential energy)), slower over the bottom (less kinetic more pressure) - and the differences in velocities can be modeled via circulation - but then there is that vector problem again. 100% of the lift is also due to Newton’s laws - the only exceptions to Newton’s laws are found in quantum mechanics and relativity - neither of which are particularly relevant to subsonic airfoils. And yet, I have heard pilots claim that the low pressure on top of a wing (over the curve) is due to Bernoulli and the higher pressure on the bottom is due to Newton. Again, nonsense. However, to get through the derivation of Bernoulli’s equations starting with Newton’s Laws applied to an ideal fluid involves math - the most direct way uses bit of calculus. Good luck with that. But, the fact that it is hard to provide a fundamentally correct explanation does not make fairy tales involving curves, flats, and venturis any less nonsense. If you cannot explain how a Gullow Jet Fire Glider generates lift with its flat balsa wing, you cannot explain how a wing generates lift. And, while we can get away with telling pilots with fairy tales, that doesn’t make them true.
@@badgyro1 Oh, it's not just me, BTW... www.grc.nasa.gov/WWW/k-12/airplane/wrong3.html And, you made me do it.... ruclips.net/video/VcFC2YOwLjs/видео.html :-)
5:22 - that is just SOOOOOOO nonsense.
Yes, and what's crazy is that folks that design 5th generation supersonic fighter aircraft believe this nonsense but what do they know, right?
@@badgyro1 I'm pretty sure that someone working on the aerodynamics for a fighter aircraft actually understands how airfoils work and concepts like circulation, downwash, the Kutta condition, and has at least a rough understanding of the Navier Stokes equations.
So are you complaining about the simplification? Or do you not feel that there is a pressure differential between the upper and lower surfaces of an airfoil caused by the Bernoulli effect that accounts for a large percentage of lift? What exactly is the "nonsense"?
@@badgyro1 One could argue that pilots do not need to know what causes lift. And, it would be hard to refute that argument given how many successful pilots don’t have a real clue. You will see lots of explanations (like in this video) that start out talking about airfoils having curved tops or looking like a cross section of a venturi. You will also hear pilots claiming that it’s Bernoulli on the top and Newton on the bottom (generally having something to do with flats and curves). But those ideas are simply not true.
An airfoil does not need to (and in many cases does not) look like a cross section of a venturi to generate lift. An airfoil does not need to have a curved top at all. Now, there are practical reasons that airfoils tend to be curved on top - introducing camber allows higher coefficients of lift and you need room for structure, but a curve is not a fundamental property of an airfoil. And clearly, a curve is not required for lift. Examples of successful flat airfoils would be paper airplanes and those cheap balsa gliders. It should be clear that they fly just fine and generate lift without a trace of a curve. So it should be equally clear that any “explanation” or “simplification” of how an airfoil works by introducing curves or cross sections of a venturi is “Soooooo nonsense”.
I will agree that it takes some effort to present an anatomically correct simplification of how a wing generates lift. If you try to introduce the concept of circulation - game over - pilots will just fade out when you get into vector algebra (in spite of the fact that this is how the back of an E6-B works). You can talk about downwash - but how does that get back to generating an actual force on the wing to hold the airplane up? Yea, more math. O.M.G. Ask an instructor if some pilots struggle with math that is as basic as weight and balance.
Now, as far as the pressure difference between the top and bottom of a wing that keeps airplanes in the air is concerned, for subsonic flow all of it can be calculated using Bernoulli’s equations (basically the tradeoff between kinetic and potential energy applied to an ideal fluid) (given the assumptions behind the equations) - flow is faster over the top (higher kinetic energy, lower pressure (less potential energy)), slower over the bottom (less kinetic more pressure) - and the differences in velocities can be modeled via circulation - but then there is that vector problem again. 100% of the lift is also due to Newton’s laws - the only exceptions to Newton’s laws are found in quantum mechanics and relativity - neither of which are particularly relevant to subsonic airfoils. And yet, I have heard pilots claim that the low pressure on top of a wing (over the curve) is due to Bernoulli and the higher pressure on the bottom is due to Newton. Again, nonsense. However, to get through the derivation of Bernoulli’s equations starting with Newton’s Laws applied to an ideal fluid involves math - the most direct way uses bit of calculus. Good luck with that.
But, the fact that it is hard to provide a fundamentally correct explanation does not make fairy tales involving curves, flats, and venturis any less nonsense. If you cannot explain how a Gullow Jet Fire Glider generates lift with its flat balsa wing, you cannot explain how a wing generates lift. And, while we can get away with telling pilots with fairy tales, that doesn’t make them true.
@@badgyro1 Oh, it's not just me, BTW... www.grc.nasa.gov/WWW/k-12/airplane/wrong3.html
And, you made me do it.... ruclips.net/video/VcFC2YOwLjs/видео.html :-)