How do Wings generate LIFT?

[@SabinCivil]

Be our dubbing partner and earn a regular income ! www.learnengineering.org/p/be-our-dubbing-partner.html

[@AlankritIndia]

Learn Engineering dubbing in which language? Hindi?

[@asitchandrapaul7032]

Learn Engineering

[@richpilotmoore1744]

Learn Engineering how can i earn regular income by dubbing?!??

[@wadechenboy]

Best cooling tech

[@anthonychessick1832]

It is so great to see this. The deflection theory is still not believed because air is not taken as having much mass density. So more must be said. Air is two pounds per cubic yard, the same weight as a quart of water. Once air has weight and mass then making it change direction will create a force. That force is lift. Thanks.

[@EASYTIGER10]

Wow! I remember when we were taught about the wing and Benoulli at school, I could never understand how or why 2 air particles must meet at the rear of the wing, but I was told I didn't understand. Yes I did!

[@xFlRSTx]

student: why does the particle on top have to reach the particle at the bottom at the same time???? teacher: you don't understand student: if you answer the question i might understand teacher: no student: why teacher: uh, i smart, i understand, you dumb, i go now

[@_NoName0]

That's incredible that the students were taught the wrong things

[@Hansulf]

Came here because I could understand how was also posible...

[@timhoward5]

You still don't understand.

[@dimitrism7446]

I remember the same as you!

[@sabinav7218]

1:58 "The two particles can leave for a completely different journey and may not meet in their lifetime." I can feel it!

[@siddharthupadhyay4246]

:(:

[@TheDubbingLtdOrNotSamin]

Damn

[@prakashmahendran]

A chemical engineer caught in comment section 🤣

[@sabinav7218]

@@prakashmahendran Machi... 🤝😉

[@gabrielsaboia4381]

Lol

[@MrWagnerMCA]

With all the aerodynamic engineers on here arguing with one another its amazing we can even design airplanes that work in the first place.

[@windowsxseven]

it's easy to make an airplane, making it a good design is the hard part

[@MakingVidsBreh]

Amen

[@deepapatricia]

🤣

[@derrickbecker9856]

Correct me if I’m wrong but can’t you account for lift by looking at the distance air has to travel from leading edge to trailing edge for each side and assume air starts and ends at these edges at the same time for both sides, and determine the speed difference between them (0.5*(v2^2-v1^2)) and plug that into L=1/2 CL rho A v^2 and determine Cl graphically from CL vs AOA

[@idekav.]

guess why their in the comments arguing: because nobody is hiring them to do a job or make something, therefore they are about as useless at engineering as you and i. the real engineers are busy actually making a difference with their lives🙂

[@justcarcrazy]

Finally! A video that properly explains aerofoil behaviour! Three thumbs up!

[@MrCharlyAndy]

Very interesting presentation. Your elucidation of the Bernoulli effect is spot on. The Coanda effect, upwash, down wash, drag as well as lift are effects. They are caused by the pressure difference between the top and the bottom of the wing. Lift occurs because of what is happening as the air flow interacts with these surfaces. Precisely at these surfaces the rate of flow is zero or near zero. This is the no-slip condition. The flow rate increases as the normal distance from those surfaces increases. What this means is that fluid shear is taking place. The fluid particles are interacting with one another and with the surface. This is not inviscid potential flow. The concept of a stream line breaks down in this boundary layer. When the wing surface is curving away from the flow, this shearing causes particles to be blown away from the surface. It is this depletion which causes a pressure decrease at that surface. It is this pressure decrease that causes the stream lines to be deflected down along and above the top surface of the wing. It is this effect that is used by the « blown flaps » on supersonic aircraft to maintain lift as they land on an aircraft carrier.

[@gksalf10]

Bernoulli himself never said anything about equal time transit, so don’t blame on him!

[@playerscience]

True, it's just people applying it the wrong way

[@Observ45er]

@@playerscience Actually people misunderstanding Bernoulli's Principle, thus, its application is wong

[@Observ45er]

Bernoulli never said anything about wings. There is also no indication in his notes that he figured out the cause and effect of the speed change/pressure relationship, only that they accompanied each other. It was Euiler, following up on Bernoulli's work that determined that a Pressure Gradient causes fluid acceleration (changes in velocity).

[@johanelbertsebastian3548]

True, Bernoulli merely stated that lift is generated by pressure differential caused by difference in airflow velocity between the top and bottom surfaces. I've only heard about the equal time theory just recently, that's why my friend sent me this video. This channel never disappoints

[@KevinChen2022]

Thanks you, I had my middle school in China, we were taught with the wrong theory. I never understood why airflow can reach the end at the same time, because it's totally wrong!

[@ronalddump4061]

Its not about whether molecules which are side by side on the front meet exactly together on the aft side. Ask yourself this: If the airspeed on top of that wing was not faster than the bottom on the average, what is happening to those extra air molecules which necessarily build up. Is the airplane, on that 10 hour flight dragging all those extra air molecules along with it? The fact is, for the last century, millions of wind tunnel test have been done measuring everything you could possibly imagine about wings. Don't you think that that issue has been measured in all that time?? Naïve. The air does move faster on the top, and that fact causes net lift. That is not that traditionally they have been right about the PREDOMINANT cause of lift. Lift is predominantly caused by plain old boring angle of attack. Btw, +schollterrorist, literally everyone reading your comment is scratching their heads in confusion about what you were actually trying to convey.

[@ronalddump4061]

It does have a longer route to take. That's the point. Btw, your original post was indecipherable.

[@jimziemer474]

Kevin Chen We are told that in the United States as well. It never made sense to me. It wasn’t until college that someone confirmed it was wrong.

[@Pewwwww_2025]

You guys were taught!!!

[@momo44444444]

you studied airfoil in middle school, bruh

[@markwaddell7853]

Terrific video and explanation. Im so glad someone took the time to give the correct lift explanation with sound engineering principle. The velocity difference is due to the two different aspects of fluid pressure that the video does not mention. There is static pressure (SP) and dynamic (or velocity) pressure (VP). The total pressure of the fluid remains the same, because TP=SP+VP. As the velocity of the air goes up, the velocity pressure goes up and the static pressure goes down, and vice versus.

[@derrickng4589]

The video provide wrong concept to the public, he use layman wrong concept instead of scientific proof.

[@HatimMech]

Bernoulli's equation applied along the streamline. For the streamlines above and below the airfoil, the total pressure is the same. But the static pressure is different (low static pressure on the top and high static pressure at the bottom). This causes a difference in the relative velocities of the particles on the streamlines.

[@josue8632]

but lift is generated by the force acting ON the surface, ACROSS a streamline. To accelerate a fluid particle there is needed to have a STREAMWISE pressure gradient, tangent to the path. It has nothing to do with normal forces that generates lift

[@XPLAlN]

@@josue8632the static pressure acts in every direction. Hence it gives both the stream wise pressure gradient and the normal force. Now you can argue forever about cause and effect but it doesn’t change this fact. Not only is it observed every time you look for it, but it must happen according to the law of conservation of energy.

[@vincentlee2460]

No one really knows how lift is generated, just like panadol, no one knows how it works to relieve pain

[@carsonk3002]

This video was excellent in clearing up potential misconceptions of the theories of lift. I really appreciated how he took the time to talk about each of the misconceptions and offer a more accurate representation of the physics at play. Moreover, the physical demonstrations and CFD simulations helped provide a more intuitive understanding of the true nature of lift. Great work!

[@عبدالرحمنالشناوي-ص7ط]

Man u dont know how much u helped me with this 7 minutes god bless u thanks a lot

[@softwarefacts5801]

Thanks for the Coanda effect.

[@TheGoldenLizard]

If you closely examine the Picture at 6:42 you can see a pressure increase at the bottom of the wing which causes a slowed air flow because "the oncoming Air particles have to push against a higher particle density" of the high pressure at the bottom. At the top because pressure decreases, oncoming particles are sucked into some sort of partial vacuum causing an inrease in flowrate at the top of the wing. An increase in flowrate means higher particle velocity at the top

[@sussybaka3420]

Thanks :)

[@timhoward5]

I have to disagree and here's why...

[@adamcherry1117]

Or more like, lower pressure zone - higher velocity, high pressure zone-lower velocity

[@adamcherry1117]

Just like using Bernoullis principle

[@derrickng4589]

You are correct, the video is misleading by ignoring the assumption of continuity equation

[@Dilidjent]

The best scientific channel ever created. Thanks for the interesting videos!

[@gloriavillapadilla4418]

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[@peterjbmenth9299]

they just go it wrong, bernoullis effect and the third law applies. this dudes videos are interestingly idiotic

[@SaiKumar-jl1jy]

The best channel for engineering students, hats off ❤️

[@YaLokalJenkemGuy619]

Something always felt wrong about the "same time" theory. Why the hell would the air be trying to catch up to its friends on the other side? Lol. Thank you!

[@krishnilmani4850]

na

[@Alex-jo9ix]

Don't say they are right, but the feel is wrong too. A foil pases and air just shift like earthquake, how can it be right? At least from a zoomed out view, if zoom in, it may be right. A theory has simplified view, but people misuse it

[@Ma-tv5qs]

The presented experiment with water sticking to the surface of the bottle is not the Coanda effect, it's just a result of surface tension, adhesion and cohesion of water molecules.

[@icrazyfish2661]

Warning: ahead are people who have all sorts of degrees in aeronautical engineering, who are intent on correcting everyone who is wrong. Please proceed with caution.

[@Razzy194]

you made this comment a LONf time ago but it's so tru i'm not even going to enter. Thank you kind sire

[@SouRGraphics]

Why is that a bad thing

[@jadenhalstead7290]

I’m wanting to go into aeronautical engineering, so having the correct information is very important for me. I’m happy that aeronautical engineers take the time to correct any wrong information

[@mazen1010]

This video gives wrong way for Bernoulli's equation application at the leading edge (A) and the trailing edge (B). As the outside air (or any fluid) is at rest (or having a uniform velocity) and at a certain pressure (depending on the altitude) at both points (A) and (B). Then the airfoil comes slashing through this uniform mass of air, and such local disturbance requires global restoration coming from the surrounding larger mass of air (energy balance must be done, and the losses will be air friction and vortex generation). However, this energy restoration faces the situation where the upper surface giving the air longer path to travel to come back to its original undisturbed condition (same velocity and same pressure). So, the energy restoration process will make the upper stream flows with increased speed than the lower stream (this is clear in the case of near sonic speed, as a shock-wave will appear at the location at the airfoil where the speed is first increased). This locally increased air speed will reduce the local pressure and cause lift. You can think of this energy disturbance and re-balancing process as a spring when it gets loaded by a slow moving body and then reacts to unload itself with increased counter speed. As for the other shapes presented by the video, the flow will detach from the surface after the first bump, and flow separation and vortices will cause high drag and the flow will never see the rest of the bumps of the airfoil, that is why it will consume the disturbance energy and restore the energy balance without generating lift.

[@mazen1010]

@Glacier The Husky I got angry because I stumbled upon this misguiding video while I was searching for a video with nice graphics to explain the correct way to understand lift over airfoils. Having arrived one year later, my only choice was to include my comment here :))

[@boston234789]

As a person that works in aviation and that I currently pursuing the airframe/powerplant license to be a aircraft maintenance technician I could tell you there is a lot of physics and electricity involved in this career

[@justinmiller2995]

This video was great! Most videos fail to address any misconceptions surrounding lift and you hit one of the larger ones on the spot, that being the equal time transit fallacy. The CFD diagrams and streamline demonstrations really help with understanding the material as these things can be difficult to visualize. However, your reference to the Coanda effect was incorrect as this phenomena only applies to jet flows, which are usually not present in standard airfoil flow. Great video and keep it up!

[@tacitdionysus3220]

Anti-Bernoulli theorists always use the 'equal time' argument. It makes it look like the wing is static and the air is moving (so the idea of two separated particles meeting again seems odd). In fact it's more the other way around; the air is static and the wing moves through it. As it slices through the air it separates particles momentarily, some going above and some below the airfoil . Inertia means that these particles tend to stay in a similar orientation to each other and substantially meet again at the trailing edge of the wing. However, the shape of the upper wing surface and the overlaying layers of air act rather like a Venturi. The air particles relative speed to the airfoil surface between those layers increases in order for the airfoil surface to flow past the same number of particles as before. This increase in dynamic pressure is countered by a loss in static pressure, due to the principle of conservation of energy, as no energy is being added to the system, the total energy (static + dynamic) must remain the same. (Coanda advocates usually express the same proposition by depicting the particles stretch further apart.) It is this lowered static pressure that generates lift; which by the way can be directly measured in wind tunnel tests and is definitely there. You can simulate it by blowing over the top of a model airfoil or even across the top of a straw stood in a liquid. The Coanda effect and reaction to the downward redirection of the relative airflow also play a part, but to dismiss the Bernoulli effect entirely is inaccurate. Differences in airfoil design can also influence the relative significance of each (e.g. a specific type of trailing edge is needed to maximise Coanda). For it all to work the airflow needs to be relatively smooth and laminar; if it becomes turbulent the effect can be substantially lost. Thats why odd (non-airfoil) shapes with longer upper surfaces are not effective for generating lift. A typical subsonic airfoil will also break down into turbulent flow at about 15 degrees angle of attack, commonly referred to as an aerodynamic stall. It results in a loss of about two thirds of the lift being generated. BTW. The compressibility of air becomes an issue as you approach the speed of sound and the fluid dynamics changes. Supersonic airfoils are a different proposition in many ways. Even today supersonic aircraft try to spend as little time as possible in the transonic phase, when the fluid dynamics transitions from one to another, and different relative airspeeds around different parts of the aircraft make things 'interesting'. NASA have a good simple explanation of much of the above on at www.nasa.gov/sites/default/files/atoms/files/foam_wing_k-12.pdf

[@Tletna]

I know this was an old comment, but it was so good, yet wrong in one or two ways, I had to comment. Part of what you stated assumed that there is no energy being added to the system. But movement of the plane through the air is adding energy. The plane must accelerate to counter act gravity. The wings are designed to aid the fight against gravity using fluid effects to its advantage, but it isn't as if any airplane can fly without initial acceleration. Force is used. Energy is redirected or added to the system. If no energy were added, then none would be used and planes could run without fuel. I'd like to live in such a world, but I don't think that invention has been discovered yet.

[@tacitdionysus3220]

@@Tletna Might need to revise your physics a bit. When in steady flight an aircraft is at a constant velocity and therefore not accelerating (a change in velocity is the definition of acceleration or deceleration). The aircraft's weight is balanced by the lift generated by the wings. The aircraft engine's thrust balances the drag generated from moving through the air. When not in steady flight (i.e. not flying straight and level, or in a steady straight climb or descent) the velocity is changing and the aircraft is either accelerating or decelerating. When accelerating up to a steady state of flight the engine power has to both overcome the energy needed for acceleration and the drag of the aircraft as it moves through the air. That's why aircraft need a lot of power for take-off, but not so much to sustain a steady state of flight once en-route. It also explains why streamlining of aircraft is so important, as it reduces drag, therefore reducing the amount of power (and fuel used) to sustain an aircraft in flight. When turning an aircraft is accelerating as its direction is changing (steep turns require extra power to overcome this). There's lots of clips on KZbin about it. Try this one for a start - kzbin.info/www/bejne/iYeUf5lvrqdqeJI

[@makmoyin]

@@Tletnait seems that the faster the plane, it just means the faster velocity of the air. More static pressure will become the dynamic pressure, this leads to a greater upward lift force. The energy of the accelerating plane is just to increase the plane speed!

[@hari4406]

Except for the fact that energy is actually added to the system.

[@hari4406]

​@@tacitdionysus3220aircraft is constantly accelerating to negate the drag forces. The constant velocity thing requires no acceleration is only applicable if there were no air resistance or drag.

[@fredrickmwengi7370]

Thanks dude for the description

[@makmoyin]

The Bernoulli theorem can apply if the air can be regarded as a laminar flow like a plastic sheet. The air particles in a layer adhere to each other like an elastic sheet.

[@K3K900]

Excellent learn engineering!!! keep the work...you make very good educational videos!! greeting from venezuela....this videos help you learn a lot better than many classes out there

[@abbieamavi]

*I could binge watch science videos forever, this was well done!*

[@anthonymontemayor1183]

I enjoyed your video! I liked how you incorporated computational fluid dynamics plots as well as creating your own experiments to back up your points. Great job pointing out the Equal Transit Time fallacy. The Coanda effect is only applicable to jet flows, as you have even stated in the video, but air acts as a continuum and does not behave like a jet in the atmosphere so it is not applicable. The shape of the airfoil causes air to stay attached, otherwise a vacuum. Great job with Newton's 3rd Law and the pressure theory!

[@adhithasimhanraghavan7516]

Total energy of a fluid that is flowing is separated into its pressure(potential energy) and kinetic energy. So, if there is a decrease in pressure, eventually the velocity component takes the edge and therefore the particle at the top travels faster than the particle at the bottom. So the tortoise never meets the cheetah ;)

[@derrickng4589]

Yes. You have pointed out the correct concept of Bernoulli's thought, This video mislead the public

[@AlankritIndia]

Wow! The most complete and accurate information on the net!

[@aabid8210]

great job +Learn Engineering. We appreciate all your hard work. Keep spreading the knowledge. We hope you get all the supports you need and carry on your work with great momentum in future. :)

[@sassyblondel]

I spent many years windsurfing and studying sail design. In windsurfing, you can feel all the forces on the sail, when it's in the sweat spot, powered up and pulling the way you want. When the draft is moving around and how a little downhaul or a carbon mast can make a lot of difference. 10 times more than on most sailboats with a fixed rig. Speaking of sails and not wings the equal and opposite forces make a lot of sense to me. Over the years, as sail technology advances and the mast become more streamlined with the sail the corresponding performance increase comes up short possibly because they are always counting on two-thirds of the lift coming from the lee side of the sail? I think like you said, it's simply how much force/ air you can bend... or stall in at times. It doesn't matter what side of the sail the power comes from. Often a larger sail will do more good than one with a more streamlined entry. Also not mentioned, and sailors know, as you get closer to the water surface the wind speed drops on average but also becomes erratic and full of flaws, eddies and swirls. Hard to generate lift in those conditions and easier to get a push.

[@matthewjackson9615]

Glad to hear your description of your experiences concerning lift forces. Goethe stated - until you feel it, you can't understand it. This proved to be the case for you. I'm glad that scientists debate scientific theories such as lift. How else can mankind arrive at the truth ?

[@LookLoLiPoP]

This is exactly what I thought when I was learning fluid dynamics at university "why they should travel with equal time?". Thank you for clearing my mind I love your channel.

[@derrickng4589]

Because your teacher definitly misunderstood the Bernoulli's principle, just like the authur of this video

[@abskargbo6576]

this is so amazing LE has really help me in my misunderstanding thanks LE

[@zsolezk]

Where were you 20 years ago when I was arguing with my fellow instructors about this? :-))))

[@PristineAnimation]

Thank you very much as such teaching stuff not available else anywhere that I learnt from this channel....

[@vonmilash823]

Even since grade school I called bs on the equal time theory. It just never made sense to me.

[@anthonybrown9373]

Wow great video I am impresssed at your hard work on this

[@Completeaerogeek]

It's not Coanda!!!!!!! Coanda doesn't work in non-accelerated flows if at all. It is viscosity and static atmospheric pressure that causes attachment. Fluids attach to curved surfaces because of viscosity. The more viscous the fluid the better is sticks and resists and the more it curves, Newton's 1st law. If you get ice contamination, even as fine as grains of sand on the aerofoil, the viscous attachment is affected as the surface is rough and attachment is not uniform. The boundary layer can break away stalling the upper surface even though it is well below the stall angle for that aerofoil. DC-9s/MD-80s are particularly sensitive to this. Attachment is a function of air's viscosity and is taken into consideration in lift calculations. As NASA says and you you can prove with a paper plane, lift is caused by turning a fluid. Bend the fluid one way and your wing goes the other. Airspeed or AOA provide the change F=MA A flat plate will generate excellent lift and low drag at a positive AOA. The pressure differences are a result of lift production from AOA, not the cause. Shaping only refines lift production. No effective AOA no lift. Remember too that all airliners have super-critical wings that are flatter on top and curved underneath. My video here explains lift production in detail that is easy to understand. kzbin.info/www/bejne/jZ67omydopaog9E

[@bigbadwolf4075]

The adhesion between liquid and soild perhaps

[@vattevineeth4567]

best video. thnks

[@julesreppert2855]

You said : "Coanda doesn't work if non-accelerated flows if at all." But here the flow IS accelerated. Why it couldn't be Coanda effect as well as viscosity ?

[@ABC-qd5oc]

This flow IS accelerated, don't forget that velocity is a vector unit. That means it has magnitude and DIRECTION properties. When a fluid flow through an aerofoil, its flow direction changes thus the flow is accelerated. And you might also remember that a particle could only accelerates when there is a force applied to it. This force is the force given to the air particles by the wing as the wing pushes the air particle DOWNWARDS. And by applying Newton's 3rd law we also knows that in turn the air particles pushes the wing in the opposite direction that is UPWARDS. This is how wings generates MOST of its lift. The Bernauli effect also plays a part at lift but it is not the central point like what outdated textbooks might say.

[@rejiequimiguing3739]

Change in air direction involves acceleration.

[@RuiPlaneSpotter]

Nice video

[@alpertugrulcelik211]

Great video! I hope to see more.

[@isaacgonzalez2930]

excelent video guys, keep the good work

[@airstories6587]

as the pressure decreases it gets converted into kinetic energy and moves faster than the air below the airfoil

[@Observ45er]

The pressure decrease above the wing also accelerates that air toward the trailing edge, therefore making it reach it sooner.

[@shamsnissan]

Thanks for making this video....otherwise I would have believed myself to be stupid my entire life...you are the best.

[@FUTUREpilot267]

If the particles don't reach the trailing edge at the same time, doesn't that mean there is a discontinuity in the flow or flow separation?

[@XPLAlN]

Flow separation just refers to when the streamlines break away from the surface, leaving only turbulent air in the gap.

[@Observ45er]

No. Because the wing separates these two bits of air, they are free to go their own merry way, independent of each other. It is the pressures that cause the different motions. There is nothing that says the two bits of air must rejoin after being separated by some solid object they flow around. Above the wing, the pressure ahead of the wing is higher than the reduced pressure above the wing, so that speeds it up toward the trailing edge. It accelerates toward the trailing edge because these two pressures.

[@Observ45er]

For a better understanding of the detailed cause of the reduced pressure *above* a wing, try this short video: kzbin.info/www/bejne/aX62opWkl7B3o68 Regards.

[@SIC66SIC66]

Great video guys!

[@suryakamalnd9888]

Does airfoil produce life even when fluid like water flows over it?

[@davidkoenig8822]

Yes. Look up what a hydrofoil is. This is a very good example of lift generation in water.

[@nitinbawali7924]

the explanation was way more crisp and easy to understand!!!!!!!

[@SabinCivil]

Dear friends, We hope you liked the video. Please support us at Patreon.com and make our educational service sustainable. www.patreon.com/LearnEngineering

[@alpha99er]

There is still the bernoulli effect in play, but this happens due to circulation theory, or the kutta- zhukosky effect, that creates a clockwise (if going right to left) vortex around the foil. it is very hard to conceptualize but, the bernoulli equation is at play, just not in the "equal time" theory sense.

[@adamcrookedsmile]

is there any chance to do a PayPal donation, like with Wikipedia? I still think MOOC course runners could use your help with creating videos.

[@SabinCivil]

We don't have an option for Paypal donation :( MOOC is a good option, I will work on it.

[@mosab643]

what about the pinching air theory?

[@yelectric1893]

Thank you for my presentation!

[@elementalsheep2672]

The reason the air moves faster over the top is the same reason that explains why water moves faster coming out of a funnel than it goes in. The air above the wing is 'sucked' towards the wing by the Coanda effect, which squishes the streamlines together. This forces them to move through a smaller space, which increases their relative speed.

[@o0prince]

Elemental Sheep I'm not sure if the funnel analogy is good for explaining this though, it's more like a funnel cut in half and a half funnel does not add speed. Correct me if I am wrong

[@christianveto5484]

o0prince i would say, the airfoil itself "takes away some space". Meaning: the air can't get trough a planes' wings. Therefore the air needs to go around that obstacle, but now it has less space. This only happens at higher speed, and it might seem confusing to us, as we can't really see the effect, but: having less space, the air gets faster, just like water beeing pushed trough a small opening. You can see how the streamlines get closer to each other in a windtunnel, when a approaching the airfoil and beeing pressed to it.

[@jorgesanchez4649]

Christian Vetö i think that is the venturi theory which was proven wrong by NASA

[@stivi739]

wrong..the wing gets lift from wind under wing lifting it..same as water skier gets lift

[@krishsymphonic6175]

I also think that ,when we take an example of two marbles placing them two different pipes. one is curve and other is straight. the marble which is placed on curve comes out faster.

[@sinanmohammadnahian4768]

I love the way this channel dont show any annoying adds or stupid intro

[@tianz4710]

3:19 is bit confusing. Why would the pressure difference have in the first place? because the wing has served as a barrier and the wind will be deflected? the direction of wind flow thus creates the air pressure difference?

[@onelvisdelarosa4116]

Thats is what is confusing me too...

[@rayz0rxxx]

Patm??

[@tomylim6022]

Well you can just imagine the airstream has a tendency of filling in all the empty space, with air. Hence when an airfoil is introduced, the region at trailing edge naturally has "the empty space" and thus creating a *high and low* pressure region. You can imagine it as simple as a diffusion process

[@AogNubJoshh]

If the air moves straight forward, there would be no air below it. That means, the air above it would be pushing down, and there would be no air below it pushing up, meaning it gets pushed down to fill the space. Does that make sense?

[@vikramgopinath8545]

This explanation is clearer than the whole video!! Thank you!!

[@anirudhmenon5280]

Great Video, I enjoyed the experiments that were conducted and like how you used Computational Fluid Analysis to aid in your argument against the Equal Transit Time Fallacy. However, you mentioned the Coanda Effect which is unfortunately only applicable to jet flows that are coincident on the leading edge and as we know air acts as a continuum and doesnt behave like a jet flow in the atmosphere, furthermore commercial aircraft are known to fly where the air flowing over the top of the airfoil does not reach jet flow speeds. Your explanation of Newton’s 3rd law and pressure theory was good and concise!

[@anomalyp8584]

4:24 why does pressure increase towards the bottom of the wing?

[@rahulmaurya3886]

IKR why??

[@jezusdepollo]

molecular attraction

[@obannon5226]

Imagine having your hand outside the window of a driving car at an angle where your hand is like a plane, that wind pressure being smashed into the middle of your palm is what give you the feeling that your hand is being pushed back a little . That angled wind pressure being forced at your palm at that angle is what causes lift. I think , idk.

[@rahulmaurya3886]

@@obannon5226 Thats absolutely true

[@r-t_verhoefzz1657]

@@obannon5226 so you're saying the air molecules are getting smashed into the bottom of the wing, basically causing an accumulation of molecules (so a high pressure)

[@kwyuenantony]

Yeah, this is the best clear explanation i read, better than many books i read which are not standard textbook and they make it too simple...i don't like the way that people always use this tear-drop shaped wing as illustration. Of course it really really helps the lift of a plane but it is not necessary for a plane to fly.

[@albireohawk]

I’ve neard his voice in my CBT for a320. No wonder it sounds familiar

[@jaythakkar3451]

Thank you so much sir I am not from engineering yet but I search it for my concept thank a lot....

[@qwertyman9560]

Bernoulli's theorem CAN be applied to two particles in different streamlines provided the flow is irrotational.

[@Observ45er]

They must also have a common ancestor and these do. The upper and lower both are originally ahead of the wing at the same pressure (atmospheric) and velocity (zero). This means they have the same energy and can both be compared with the Equation.

[@samuelcarvalho3691]

BROOO!!! THIS VIDEO LITERALLY CLEARED ALL MY DOUBTs, I used to keep wonder how how how, and now this finally all made sense tysm,mgby

[@SohilShah_Melodyman]

Well explained........But have a question! Due to coanda effect,the pressure is decreasing from top to bottom as we go towards the airfoil on the upper side. I agree to that! However,why can't we apply the same concept for the air flowing on the lower side of the airfoil.What I mean to say is that even if the pressure is considered to be decreasing from atmospheric value to some lower value towards the airfoil on the lower side,still the coanda effect will be met! Please clarify!

[@rmhayes1954]

The air particles in the flow stream have mass and their momentum would try to keep them moving in a straight line, but the tail end of the top surface is dropping away from that straight line. This causes a lower pressure between the flow stream and the surface than above the flow stream, which puts a downward force on the particle and lets it approximately follow the shape of the top surface while the lower pressure (relative to the bottom surface pressure) pulls up on the wing. Below the wing, the surface is dropping toward the flow stream, compressing the particles and increasing pressure between the bottom surface and the particle. That again produces an upward force on the wing. Two different conditions, both producing lift (and drag).

[@甘いお茶漬け]

Best lesics video i’ve seen

[@LORENSSIOK]

Good explanation! Thank you for the research. And for those who ask about the Coanda effect, search Henri Coanda, he made the "first" plane with a jet engine in 1910, named the Coanda-1910

[@Purplits]

thanks, needed this for my essay

[@maxradke2189]

my whole life is a lie...

[@maxradke2189]

+someusguysmusic wtf? I thought that athiests ruled the internet, what are you doing here?

[@maxradke2189]

+someusguysmusic why so hostile bro? I was just pointing out how athiests like to waste their time looking at dank memes and porn on the internet, hence why they rule it.

[@GoldSrc_]

+someusguymusic Turn to Allah before it's too late :P.

[@ArcHelios117]

He said his life was already a lie. Why should he make it an even bigger lie ?

[@mocskoskukorica]

He spent 3 minutes with explaining the nothing......

[@auzernijat641]

thank you, awesome video indeed!

[@guysquarred]

Very Interesting, but I think that the truth is between theses two theories. As you shown airflow above the wing is faster, so along this streamline Bernoulli principle applies and lower the pressure of the air flowing above the wing. In the mean time the airflow below the wing is not as fast so the pressure doesn't drop as much, this creates lift too! So Bernoulli principle can explain lift even if equal time argument is wrong. Speaking about the equal time argument. I agree that in a wind tunnel where there is an airflow over a stationnary wing nothing tells us that the air should travel the same distance. But there is two things to take in consideration. First (I'm not sure about that ) the air flow above the wing go through a narrower path, and since the pressure doesn't go up(no flux) , it must flow faster to conserve the flux. Second, in real airplane it's the wing that is moving through relatively static air, in that case the equal time argument makes sense because the air is displaced verticaly but not horizontaly, so the horizontal position relative to the wing stays the same for all the air (due to inertia). In that case the geometry of the wing lead to a longer path for the same horizontal distance. And at last I'm not convinced by your argument about the reversed shape, yes the third law of motion is stronger in your example but none of your wings are aerodynamic and the dragging that this generate could counter any lift produced by Bernoulli principle. I'm no physicist so any feedback are welcome.

[@ronalddump4061]

You are neglecting one thing. Lift on wings is caused predominantly by simple, boring, angle of attack. Bernoulis principle does cause lift in wings shaped appropriately, but certainly not enough to lift the aircraft. Wings have been shaped that way to make them as efficient as possible. And, yes, it might sound too quaint for folks who love to strut their stuff on utube, but that air moving faster over the top of the wing is essentially caused by the fact that the air must move faster, because that side of the wing is longer. If the air does not stay in the same place in the sky, where is all the extra air stored that "didn't make it there" as the plane flies for 10 hours. Thus, in fact, essentially, the "equal time" thing is accurate. The fact that two molecules which were side by side, are not side by side, is utterly irrelevant. On the average the molecules are staying in the same part of the sky. So the speed over the wing must be higher.

[@brian-kt1rc]

I prefer the visual from 6 mins onwards and specifically 6:17 and 6:28. The important thing is the high pressure zone in the front of the wing, this is the most important thing. This slows air trying to get over top surface of wing relative to the air above it. This creates a gap that can be seen. this air which is now compressed two streams into almost one rushes into this unfilled zone. This unfilled zone is a low pressure and the high pressure air rushes (accelerates down wing top surface). The air below the wing hits high pressure zone and slows down pushing wing up. So we have high pressure air at bottom of wing and in front of wing, normal pressure air far above wing and low pressure air on upper wing surface. The compressed air coming over the wing speeds up into the low pressure zone

[@raynixon6767]

As you get closer to the upper surface of the wing, the acceleration of the air is increasing due to conservation of angular momentum.

[@battulaharilakshmanprasad2721]

Could you explain it more detaily

[@20891]

@@battulaharilakshmanprasad2721 it’s simple . Stable Slower air on bottom will bounce the downward of fast moving air from top- hence causing lift. No need to engineering degree to understand

[@ialeg3710]

(Sorry for eventual poor english.) 1:59 Welp,based on the diagram,Bernoulli still applies because faster fluids have lower pressure and slower fluids have higer pressure,so the wing will be still pushed up due to difference between pressure I was taught lift using the flow tube concept,a region of space made of all flow lines that pass through a closed curve,and the continuity equation,which basically says that the same volume of fluid that enters a tube section also exits the subsequent tube section,no matter how wide said section is. There is a flow tube below the airfoil and above the airfoil,the flow tube above will have a narrower section than the tube below due to the shape of the airfoil,so the air volume the enters said tube will have to be faster than the same volume that enters the tube below,being faster,the upper volume will have a lower pressure than the volume below thus creating lift. Equal time argument is used as an intuitive explanation of lift.

[@rohitchaudhary3619]

Yes but flow should be irrotational

[@dineshrajeswaran6684]

I CANT UNDERSTAND THE STATEMENT "THE SAME REASON PRESSURE SHOULD INCREASE AS WE MOVE TOWARD THE AIRFOIL AT THE BOTTOM"

[@SindhiScienceChannel]

I wasted lot of time to understand nothing out of this video.

[@phoenixamaranth]

I know this is nearly a year late, but he was referring to the gradient of pressure as you get closer to the airfoil from the underside. If you were 10 meters away below the airfoil the pressure would be less than if you were a couple of centimeters away from the bottom of the airfoil. It was a complicated way to say that the air under the airfoil is being compressed so the pressure is higher.

[@badamsvrenmonhbayr8773]

@@phoenixamaranth ggc😡🚘🚘🚉🚉🚟🚞🚞 mm9 🚟6

[@hubaibkhan7658]

@@phoenixamaranth but isn"t the air above also being compressed then why pressure is getting less for that

[@amonkeywall]

@@hubaibkhan7658 you have the exact right idea. The logic in this video is flawed. In reality the streamlines are attached to the surface of the airfoil because of viscous effects and the boundary layer that forms on the surface

[@laiomarinheiro7745]

This video is very interesting. I just think that the "coanda effect" is not exactly the most assertive way of explaining the flow circulation (and lift). Classical literature generally refers to Kutta condition , in which nature "chooses" the exact ammount of circulation around an airfoil such as flow could "always" leave the airfoil smoothly at trailing edge ... this is why, irregardless of thickness, leading edge radius, or even camber... Lifting bodies always will present sharp trailing edges... this kind of geometry will generate flow fields patterns in which velocity at the upper side achieve higher magnitudes (which is related to lower pressures by Bernoully's equation) than at the botton (well considering a positive angle of attack).

[@Eltaurus]

The overall logic of the video is somewhat questionable. The whole explanation is reduced to the existence of Coandă effect, which is not explained in terms of general laws of physics, but just taken as it is. As a result the key point here suggests that curvature of the flow produces the pressure gradient, when in fact it's the other way around. Like in the Newton's second law acceleration is not the reason but the consequence of the existent force. The second mistake 2:07 "you cannot apply Bernoulli Equation between two streamlines". This is not how you compare parameters of the flow in points A and B. In order to do this you need to write Bernoulli Equation twice: 1) for the upper streamline in point A and at infinity 2) for the lower streamline in point B and at infinity However, as the parameters for both streamlines at infinity are the same, you can put equality between parameters' combinations in points A and B. So the inequality sign in the video is wrong. Actually Bernoulli Equation can be applied to explain the differences in flow speed you talk about at the end of the video: since the pressure above the wing is lower, the air here flows faster. It's that simple.

[@Observ45er]

Yes you can apply Bernoulli Equation between two streamlines when the two have the same ancestor starting at the same pressure and velocity. This gives them both the same Bernoulli constant. The two both start far ahead of the wing at the same pressure (atmospheric) and speed (zero). This is explained in John Anderson's book and Charles Eastlake's Physics Teacher article.

[@isagumus1]

Oh my god what a great explanation is it :D

[@shubhambansal3023]

Hey, I think flow separation also might cause lift. when flow past the upper layer of foil and curvature is quite large in that flow separation might take place at lower portion of foil. Thus causing vacuum in that region. thus ultimately leading to pressure gradient and upward lift.

[@noahschott8690]

Thank you for explaining the Coanda effect and its role in generating lift. I appreciate how you debunked the common misconception that Bernoulli's principle is solely responsible for lift. However, I would have liked to see some visual aids or animations to help illustrate the concept of flow curvature and how it generates pressure differences. Overall, great video!

[@parthsangal5672]

I guess in 2:29, the figure actually has a deep CONCAVE surface in its middle so the airflow cannot be bent that way like it does in airfoil (COANDA EFFECT) and thus it doesn't create any lift.....hope my explanation is correct 😊😊

[@hyprk5590]

Wow.. my university physics book has also a wrong explanation!!!! Thank you for uploading this video.

[@JacobDavidCCunningham]

The water running over the bottle isn't surface tension? Also I don't get this diagram at 4:23, if equilibrium goes from High to low, why does your diagram point the opposite direction? If there's high pressure above the wing, and low below the wing, wouldn't that push the wing down and thus the entire plane with it, since the plane is attached to the wings? 4:51 This airfoil-profile example would be better if it was upside down, that blunt-face at the bottom would be better at the top. I believe(haha) that a higher camber would be better/make sense to be applied at the top of a wing than the bottom. Otherwise it's almost like an upside-down flat-bottom airfoil. I think overall the lift-factor comes from deflecting air-downwards not because of "coanda effect" but just by pushing the air downwards like a ramp pushes something upwards, the airfoil/tear drop shape is to reduce drag. edit: yeap and apparently what I said is wrong (of course) www.grc.nasa.gov/www/k-12/airplane/wrong2.html I am not aerospace engineer. I'm probably wrong I suppose. Although I've built a lot of model planes, have obsessed about aviation, read/watched a lot of material but I will admit I still can't mathematically or even verbally explain lift to prove that I can lift something. I only work with a "known good airfoil shape" wing loading, and watts/lb rating to make sure something flies. But then again these are just toys and I am not an aerospace engineer.

[@wbeaty]

> The water running over the bottle isn't surface tension? Dr. Denker from av8n.com has the same objection. I think he's wrong, but the issue is just terminology. Underwater, a fluid jet will follow a surface. This is traditionally called "flow attachment" rather than "Coanda Effect." And in air, a jet of air will follow a surface, same flow-attachment. It's only when using water jets in air, that issues of molecular adhesion and surface-tension issues will cause confusion. So, take the whole demonstration underwater, and use a dye-colored jet to show the attachment of the flow to a curved surface. Or, use a smoke-jet in air, to show that gas-flows immersed in gas will still attach. (Note that gasses have no adhesion forces at all. Yet the jet still sticks to the curved surface! Coanda Effect was never being caused by the chemical bonding between molecules of a liquid.)

[@JacobDavidCCunningham]

wbeaty thanks for the clarification

[@JacobDavidCCunningham]

dutchrjen thanks for the clarification

[@rmhayes1954]

I think you've missed a part. It's not that the air pressure pushes the air down to stick to the top surface. The Coanda effect - tendency of the fluid to parallel to the surface - causes air particles to move downward as you move toward the trailing edge, separating molecules and decreasing pressure. Pressure is a measure of particles banging against the surface, so as the surface drops it is moving away from the flow stream and has less impacts (lower pressure). The smooth airfoil shape, compared to say a tilted flat surface, helps stop the stream from separating from the surface so the upper stream leaves the tail section with a downward trajectory. Pushing the air down results in pushing the wing up (Newton's 3rd).

[@JacobDavidCCunningham]

I'll have to read this again, right now I can't seem to focus/get it. Pictures would help haha. I could understand if the air going downwards is "pushing up" on the bottom of the wing, what about the top part? Anyway yeah I'm pretty tired at the moment, I'd have to dissect your response with a clear mind.

[@sabergaballah6149]

Excellent and fantastic and excellent effort and explaining. Thank you very much for a golden information

[@mohamedsherif4096]

The speed of air is higher at the top of the wing and slower at the bottom, as the speed of a fluid increases it’s pressure decreases, so that the pressure at the top is lower so the lift is created

[@ajaxkhan102]

The newton 3 law argument was so beautiful and simple that it made my day.....its beauty of proof cant be contradicted

[@Dalekmun2010Two]

A video that does a great job at explaining why one system doesn't work, but totally fails at explaining why another does work. Fantastic.

[@lordraj365]

Exactly!!! same thought. Even i couldnt understand the 2nd way. May be their motive was to bust the myth

[@owengarber1493]

Good explanation! However, I have found many people saying the coanda effect is what is causing the flow to remain attached to the airfoil. I would point out that the coanda effect only applies to jet flow, which the airfoil does not experience.

[@sumitw7]

hey ...does the reaction turbine works on coanda effect also ?? i always thought it is due to the nozzle type shape between blades which causes fluid to accelerate and turbine moves due to reaction from fluid to this acceleration ?

[@danybinoym384]

thank you for teaching me what is bernoullis principle

[@kagankarakoc1103]

I love your channel and videos, very open minding! but for this video when the plane flies upside down shouldnt it fell towards the ground?

[@khaledaljabri6770]

Here's my simple explanation for the last question, which is likely to be wrong or right: - As you illustrated, there's high pressure under the wing, and low pressure over it, and the relationship between pressure and velocity is inversely proportional. Consequently, air over the wing will have much more speed then the air under the wing.

[@luisboza-u3c]

OLD THEORIES ARE OK . YOU BET

[@MrZz108]

You lost me at 4:10 to 4:25. The video seems to be contradicting yourself. Pout > Pin for the top, but it is the opposite for the bottom of the foil. Also, in the example given, the curvature at the top is greater than the curvature at the bottom, so according to their own explanation, there should be a net downforce on the wing. Can someone help me understand? Other than the angle of attack, why is the pressure greater at the bottom? Is it just because the pressure drop at the top is greater than the pressure drop at the bottom (so the bottom of the wing is closer to atmospheric)? Thanks.

[@SabinCivil]

Ohh, watch it carefully once again. Pout > Pin for both the top and bottom. At both top and bottom flow is curved downwards. Faraway from the top pressure is atmospheric and faraway from the bottom pressure is atmospheric. Apply these facts carefully, you will see why there is a pressure difference.

[@MrZz108]

Ohhhhh okay. It finally clicked. The pressure difference is relative to the streamline of the particle, and not the wing itself. So the radial acceleration of each air particle is what creates the lift pressure as a function of v^2/r.

[@fsho5260]

Why is Pout on the bottom, above Pin? This means that by applying the Coanda effect for the air flowing under the wing, the air there would have a net downward force because of higher pressure closer to the wing and lower pressure further from the wing if Pout and Pin are oriented as you described. I know this makes no sense since lift generated in real life, so can anyone help?

[@fndTenorio]

4:25 this is not what pressure heatmaps show. Pressure decreases towards the airfoil both on top and on the bottom.

[@shivamrai1179]

You people are awesome... Please come to India I want to meet you people... Respect. Salute.

[@wbeaty]

Pretty good, but... First animation is wrong. Whenever there's no "phase shift" between the upper and lower flows, then lift equals zero. (The animation shows the zero-lift condition, but wrongly includes a big arrow labeled "Lift!" Doh! ) Second: "Equal time argument" has little to do with explanations using Bernoulli. (Bernoulli explains lift, as long as you don't include the incorrect "equal transit time" explanation as part of it. Newton and Bernoulli are equal, with each taking a different approach.) Third, in a 2-D world, the flow approaching the airfoil has roughly the same shape as the flow departing (because, circulation!) Yet some these diagrams show air approaching horizontally, then leaving with downward deflection. Nope, not in 2D diagrams, nor in 2D simulations. Only in a 3D world can we deflect air downwards, where afterwards it remains flowing downwards. Two-dimensional diagrams are different. In 2D, the air rises to meet the leading edge (not shown in diagrams here.) Then it equally descends when passing the trailing edge; an effect caused by closed-loop flow lines of circulation. After the airfoil has passed, the parcels stop moving downwards. In other words, flight in a 2D world is "ground effect flight" or "venturi flight," where 100% of the lifting force is applied directly against the airfoil and the distant ground surface. Flying higher and higher doesn't let the 2D airfoil escape from "ground effect," instead it just makes the pressure-pattern wider and wider on the ground, while the net force remains undiminished. We cannot get rid of the ground by moving it far away. Yet in 3D, none of this weird stuff is happening. Flight: it's inherently a 3D effect, with momentum deposited into air itself, and 2D flow diagrams cannot explain it. I think the attempts to explain 3D physics using 2D airfoil diagrams will just introduce a new set of student-confusions and misconceptions. But I don't think it's impossible to explain 3D flight: start with a hovering hummingbird or bumblebee or helicopter, and go from there, since the level flight of winged craft is just a distorted version of "hovering air-pump flight". The physics of 3D flight contains stunning insights, and some quite simple explanations, but these cannot be seen unless first we tear ourselves loose from beginners' textbooks and the 2D airfoil diagrams they religiously employ. (Search on SJ Gould's papar about "creeping fox terrier clone" effect. We use 2D diagrams, not because they're the best explanation, but because earlier texts did.) Instead, shatter the religion: become blasphemous heretics who start out with the 3D flows around helicopters/bumblebees/motorboats or even rowboats, and only end with 2D airfoils. Heh, on the other hand, the rest here is excellent!

[@SabinCivil]

Good observations ! 1) You are right regarding the first animation diagram - That is a symmetrical airfoil at zero angle of attack. It should not have produced any lift. Sorry for the mistake in the drawing. 2) An asymmetrical pressure distribution is setup around an airfoil - In top surface, in most of the region pressure gradient is negative . While in bottom surface in most of the region pressure gradient is positive. This pressure distribution can completely be explained with Coanda effect and 'outer region of a circular flow - higher pressure' concept. This pressure gradient is what responsible for high speed flow at top and low speed at bottom. Not the reverse. What I mean is, with pressure distribution we can explain speed variation in this case, but we cannot explain pressure distribution with speed variation. The reason is that there is no logical explanation what causes this speed variation if you follow the latter approach. Anyway we will explain these things graphically in our second video. 3) I don't agree with what you said about 2D simulations. Please check CFD simulations done by Cambridge university. Flow is deflected downwards at the downstream.

[@wbeaty]

> explained with Coanda effect Dr. Denker at av8n.com insists that Coanda Effect only applies to water jets in air. That's wrong, but he has a point: in aerodynamics we call the Coanda Effect by the name "Flow Attachment." > 3) I don't agree with what you said about 2D simulations. Please check CFD simulations done by Cambridge university. Flow is deflected downwards at the downstream. Yep, Babinski gets it mostly right, though a latecomer to this 1990s controversy. See my refs at amasci.com/wing/airfoil.html#L1 The classic papers by the guy who started all this are 1990, Klaus Weltner, U. Frankfurt. If the airfoil in Babinski's smoke-tunnel doesn't make contact with the vertical walls, then it's no longer a proper 2D situation as depicted in textbooks. In that case, we have flow over the wingtips, and a 3D situation with a trailing vortex-wake, and non-circular streamlines of circulation. When the airfoil tips do contact the vertical walls, then only 2D flows exist. ANd then the upwash ahead of the foil is the same as the downwash behind. However, if the span is shorter than the windtunnel width, and the flow is 3D, then we actually have a 2D slice of a 3D pattern. In that case the flow does not match that of a 2D diagram. Instead, we'll see a horizontal incoming upstream flow, and a downwards-tilted diagonal flow in the wake behind the airfoil. This only appears in 3D, when a vortex-pair is being created. I wasn't clear enough earlier. In all 2D simulations (and in wind tunnels with wingtips against walls,) the flow is *deflected upwards ahead of the wing,* and deflected equally downwards behind the wing. This is a consequence of closed lines of circulation superposed upon the horizontal flow. Any parcel that flows downwards behind the airfoil, earlier moved upwards ahead of the airfoil. It must do this, since circulation streamlines are circles. Far ahead of the airfoil, the air is rising. Far behind the airfoil the air is falling. Simple circulation. Why is this a problem? Because this process does not exist in real-world 3D aircraft, and so a 2D diagram does not explain flight. At all. It's completely an artifact of an INFINITELY-WIDE WINGSPAN. In 3D aircraft, the wing is a pump, and the circulation isn't closed loops, but instead becomes part of shed vorticity. The consequences of this are major. As a consequence, in 3D aircraft, far ahead of the airfoil the air is *not rising*. And, far behind the airfoil the air is *greatly falling*, as part of a descending, momentum-carrying vortex-wake. The wing has dumped momentum into the air, and now the air is falling rapidly. In 3D, the circulation streamlines are open, and they spiral off into this downstream wake, where the flow is carrying off net downward-momentum, much like a sideways-translating helicopter in level flight. But in 2D, none of this is happening. With two-dimensional airfoils, the air is pulled-up-then-pulled-down, and zero momentum is injected into the downstream air. Instead, with 2D airfoils there arises an instantaneous contact-force between airfoil and distant ground: a "venturi" phenomenon where the force-pair is entirely between solid surfaces, and zero momentum is shed into the air itself. No matter how distant the ground, 100% of the airfoil weight is pressing down upon it. So, two-dimensional diagrams inherently depict ground-effect flight. In other words, a 3D diagram is utterly different than a 2D diagram because the 3D diagram includes momentum-dumping and vortex-shedding, and vortex-shedding is the central process of lift-production in aircraft. Yes, low-level textbooks ignore this, but not because it's too complicated. It's because their authors apparently have a long-standing misconception. It's this one: *They assume that the Newtonian force-pair is entirely between the upper and lower wing surfaces.* That's a violation of Newton. It's "lifting yourself by your bootstraps." So then, what's the difference between a 2D diagram versus a 3D diagram? Look to the main Newtonian force-pair. In the 2D diagram, the force-pair is between the airfoil and the distant ground. (Again, it's not between the upper and lower wing surfaces.) In 2D, the airfoil is pushed up, and the ground is pushed equally down; an action-reaction pair. Do real airplanes fly by pushing against the ground? No! If they did, then horizontal "lift" would be forbidden, and banking turns would become impossible. Instead, only an infinitely-wide wing will push against the ground. No matter how high the altitude of an infinite-span airfoil, it's always pushing against the ground. 2D diagrams are depicting 100% ground-effect flight of infinitely-wide wings. But unfortunately, they don't include the ground in their explanation, and the typical explanation doesn't even mention this serious flaw. That's easily forgiven in children's books. But the same flaw appears throughout all of aerodynamics, at every level. 3D diagrams are fundamentally different. In 3D, the force-pair of Lift doesn't contact the distant ground. With 3D wings, the force-pair is entirely between the airfoil and the shed vorticity in the air alone, where the parcels in the downstream vortex-pattern are carrying away the down-momentum. The downstream "tip vortex" contains all the momentum; it's essentially a rocket-exhaust. Or, we could view the wing's vortex-wake as the jet of water flung backwards by a speedboat, or the jet of air flung downwards below a hovering helicopter or hummingbird. In all these situations, the thrust is an obvious consequence of action-reaction against a mass-carrying fluid jet, where the foil is launching a momentum-carrying "exhaust plume." 3D wings do this, but it may not be obvious, because the wing translates horizontally, so the downwards fluid jet is greatly stretched out. 3D helicopter blades give a clearer example. Put simply, flight is a matter of dynamic thrust-production and vortex-shedding, and 2D diagrams which don't depict this, are teaching us that aircraft can "pull themselves up by their bootstraps" and directly violate all three Newton's laws. 2D diagrams are a helpful learning tool, as long as everyone is well aware that these diagrams are *fundamentally un-physical.* I strongly suspect that this issue is the origin of much student confusion. Their teachers think they understand flight, but actually their explanations are violating Newton. They dismiss these major issues as being "mere tip vorticies which we can ignore." Then, their students don't notice the newton-violations, and as a consequence, their learned concepts cannot connect with the rest of physics, and they never completely grasp how flight works. They've been taught the physics of infintely-wide wings and ground-effect WIG flight, and they only understand that alone. Real aircraft fly by a very different mechanism, and they were never taught this mechanism. Put simply: if we "simplify" our explanations by going to a 2D model, that's called "making a mistake." Other than ground-effect mode, 2D models don't explain flight.

[@googelplussucksys5889]

Fascinating, but I don't think you are fairly representing 2D aerodynamics here.

[@anthonybrown9373]

That's why God invenented Quantum Physics.

[@qmvufgsh8920]

This is a real way to do science. Keep debating and questioning

[@civilengineeringmotivation2302]

Very Nice Content !! you deserve more subscribers

[@shivpratapsinghsengar3743]

India waalein like thoko yaha saala 11th mein hi jee ke liye ye sab padha Diya tha.Damn we are ahead of the curve.but anyway this video was so much better than teacher explanation though

[@namthainam]

OMG thank you!!! My intuition always told me the equal time concept did not make sense. I feel so much better after watching your explanation! Thank you again!

[@peterjbmenth9299]

ur an idiot

[@PersonOfBook]

How planes can still fly upside down then?

[@rejiequimiguing1279]

Blind Faith newtons 3rd law

[@inferno7181]

magic

[@jcdominguez2015]

symmetrical airfoil

[@dertery3619]

The same reason how it can land..

[@johnreytabares4611]

It rolls 360° for a short period of time only.

[@HusnainRehmat395shakargarh]

Very helpful🔔

[@saikrishnapadamata3884]

well explained, appreciated !!!

[@marcodiscendenti4059]

"We know in a curved flow outside pressure should be larger" Why? "Outside" with respect to what?

[@googelplussucksys5889]

It's awkwardly explained... if you drive into a curve, you will be pushed out and in the same way a curved flow experiences increased pressure along its outer edge and vice versa.

[@marcodiscendenti4059]

Which fluid-dynamical principle can explain this?

[@googelplussucksys5889]

Marco Discendenti I don't know what the name for it is, if there is one.

[@amonkeywall]

This isn't true at all. In the video he's using a "logical" argument by saying that the only way for the streamline to stick to the surface, there must be a pressure on the outside pushing it towards the airfoil. But the same applies to the bottom surface. The only way for lift to generate then, is if the pressure pushing the streamline into the bottom surface is higher than on the top surface. But there is no logical reason to think that there is a difference. In reality, the streamlines are attached to the surface because of viscous action

[@thescholarmohammed2550]

Who’s with me the BEST thing in the world!!! I wish I was this guy he is the best❤️❤️❤️

[@flymario8046]

But then why does my flat winged planes fly? Shouldn't the air travel on both sides of the wings at the same rate thus creating no lift. Now I know that you are likely going to say that the wing being tilted up will generate lower pressure at the top. But still... this has bothered me.

[@ronalddump4061]

because as few seem to want to point out, wings lift predominantly because of simple angle of attack. Air molecules hit the bottom of the wing , thus driving the wing upward. The shape of the wings make the system more efficient. People have a difficult time visualizing that 2 things can be at work at once. Also, people like to make utube vids, so they like to make things as complicated and mysterious as possible

[@BariumCobaltNitrog3n]

The air doesn't move past the wing, the wing moves past the air. The air particles only move up and down, not left to right. The air particles above the wing move farther than below the wing from their original position, and are pulled downward as the wing passes the particle by the Coanda effect. The air is not moving fast or slow, it is stationary.