Forget Bernoulli and Newton | The easy way to explain lift 

It’s such a pleasure to see someone admit that their previous knowledge was incorrect and unabashedly correct themselves when presented with better information. And THAT is what makes you a true scholar. Well done, please keep these videos coming 👍🏼

I was fortunate to have flight instructors who gave me excellent rules of thumb with a certain amount of humour: "take 2 parts of Bernoulli, 1 part of Newton. Some times it's the other way around" - followed by going inverted in an aerobatics plane. 😆 That has always worked for me. Once I stopped screaming. 🤣 (no, I didn't really scream, I loved it!)

I find the explanation in the beginning to be the best. A wing encountering still air takes that air and moves it from a higher place to a lower place. That requires a force. The equal and opposite force is the lift.

It's refreshing to see someone admit their earlier work was not correct and then come on here to correct. Big respect! And thanks for the clarification!

Hei Magnar, Quite an improvement which I can follow nearly to the end. There is still a confusion re Bernoulli's. We must not forget about viscosity, bounder layer, energy, Joule Thomsen, and more Bernoulli's is valid along a single streamline. Many professors over the years have differences in understanding and explanations. The sum of it all is quite up to what I learned taking my engineering degree in 1979. We must integrate the work done (Newton) by deflecting a mass of air, a fluid, The equilibrium sum equals that halves of the lift comes from the upward deflection up front of the wing, the other halve from the deflected air leaving the trailing edge, i.e. the "vast" the energy is picked out, no more to gain from it. The pressure and temperature changes involved in the process can not pr Bernoulli's definition directly be linked to the process. No fluid likes to be disturbed, moving it is a mass that are to be moved and needs energy. The viscosity forces keep the fluid together which also needs energy to overcome. This in total can be linked to Newton. The rest of what happens are in many ways side effects. Stretching and compressing the fluid while we are moving the mass around. Air has mass as everything else trying to move it around, accelerate it demands energy / forces. 1 kg of air or 1 kg of steel is no difference F=m*a. Except viscosity compressibility etc. Air will by this be more "soft" to move around, like suspended by a rubber band, similar as if the 1 kg of steel was suspended by a rubber band. You can not simply always say Ps1+Pd1= Ps2+Pd2. You can have different velocities but the pressure remains the same. As you demonstrate by blowing down your strait henging papir sheet, flowing air at one side, no flow at the other side of the papir sheet. Pretty presise metering instrument are in use which utilize the effect of Bernoulli's. Venturi Orifice plate, V-cone. Static pressure drop while the flow velocity increase. Rule of tumb pressure drop equals the differences i pipe diameters d/D which are named the beta value, +discharge coefficient adjustments. There is no beta value in free space around an airplane it becomes infinite. A curiosity from the old faction explanation of lift and Bernoulli's you can not split a venturi i halve and say you have "the upper surface" of a wing.

short add. We must consider what comes first, pressure changes or mass deflection?. Our first action is initiated by moving / displacing the mass package. Than by the inertia, the compressibility and viscosity, i.e. stretching of the rubber band comes the changes in pressure and the adiabatic temperatur changes. A continuous process.

I'll have to watch this a few more times to understand that A, B, C, & D thing. Thank you for the lesson!

Look at the larger picture and lessen the confusion: a heavier than air aircraft can sustain itself in flight ONLY by accelerating a mass of air downward with sufficient force to counter the force of gravity. Regardless of what goes on on the top or bottom of the wing, or on any other aerodynamic surface, the net effect of the interaction must be that air is accelerated downward, or the aircraft will fall toward the ground. Hope this helps.

I learnt a lot from both the videos. Thank you, Sir.

Great job explaining lift that too in simple words!! From your previous video I first learned that what I had learned about lift was wrong, and from this video I learned the correct explanation for lift!! 👍

There are problems with this at 5:00 . The forces at B and C are opposite at the leading and trailing tips due to inverted curvature thus cancelling total lift. At the tips the lift cancels the lift at the center. This can also be seen by the lack of downward airflow on the right outgoing side when compared to the incoming left side. No total downward flow, no total lift !

From ‘Stick and Rudder’. It’s all about angle of attack to the relative wind.

Really enjoyed the video. For us laymen who are not versed in higher mathematics it really helps. Do you also have a video like this that explains the other forces on an airplane such as thrust and drag, etc. Thank you😊

Aaahhhh, finally the truth, and guidance on how to explain it correctly. Thank you!

Excellent information.

Great explanation 👍👍

Another wonderful video. As I said in my comment to that video, my college professor would be proud of your explanations.

really interesting -many thanks

I was waiting to see F=ma and it finally was presented. Like everywhere else you have to do work on a fluid mass within a period of time and out of that you get a lifting force vector (minus all the losses). Thanks for the nicely done explanation.

I learn so many things ....thank you 💎 gem❤️

I like both videos. I had given "lift" some thought before. There are many questions in Physics that can be analysed in multiple ways. For instance, you can't make a paper thin wing. It would have no strength. But the airfoil shape has a cross section known to minimize drag and can be designed to have some strength. You can make it curved and adjust the angle of attack such that it accelerates air with a downward component. F=ma will give a value for lift. If you consider the individual molecules and their average velocity, then when air is moving, molecules will impact preferentially in the direction of flow and simultaneously have less of their velocity perpendicular to their motion. That would be a way to explain what is at the root of Bernouli's principle. And from there, proceed with the rest. So what a lot of Physics amount to is rules that we expect to hold, when applied correctly. And we use them to disprove errors in our understanding and hopefully get clues to better insights.

Great vdeo! thanks!

Wow i love this...thank you sir

Thank you!

Your video should have more views, my aeronautics bachelors degree don´t understand this, and many of the faults are the FAA and his technical publications

So many interesting comments here! I think it deserves a video on how the pressure explanation is valid with a flat sheet style wing. Which certainly flies. When I was taught aerodynamics for my pilots exam, I was told that Newtonian forces made up 70% of lift, with rest being Bernoulli forces…

To me, the aerofoil can also be thought of as the most efficient shape required at the chosen AoA. Certainly your description of airliner wing profiles fits this logic?

The diagram at 5:37 illustrates two-dimensional flow (i.e., infinite wingspan or a wing that goes from one wall of the wind tunnel to the other wall - no wing tips). We operate in three-dimensions (with a finite wingspan) which produces wing tip vortices, downwash, and lift (by imparting downward velocity to a large air mass).

Very Good - Thank You ! ! 🙂😎👍

3:00 you can see in one instance he holds the paper correctly with an airfoil in it to show Bernoulli working. Then he holds the paper with a tension crease in it to show Bernoulli not working. The fact is that if you use a fair test, the paper responds as expected. I've seen this more than once, and I can't decide if those who do it are just ignorant or deceptive.

The confusion in the minds of many is in the word LIFT. Showing the high-speed/low-pressure airflow above the wing makes one think that the low pressure is lifting the airfoil when in fact, it's the higher pressure below the wing that is pushing the airfoil upward. Low pressure doesn't pull; high pressure pushes and symmetrical airfoils work just fine as long as the angle of attack is positive.

The Bernoulli principle applied to the prop is that the force going on downward side has more speed that the side going up basically, P factor in making the plane want to turn left a little, this down and right thrust is added to the motor. Really a prop provides lift the same way of a wing foil. Easily explained lift is the result of thrust equals Drag, lift equals weight. Speed applied lowers weight value due to less time to react to gravity, and increases lift, air reflected in another direction by a horizontal surface. So airspeed vs the amount of surface defelction, increases lift more and more. Conventional wings of Cessna, Beechcraft, have enough surface, although incrases drag, slower overall cruise, but to me is worth it, compared to more narrow wings needing more speed to stay aloft.

What about aerobatics aircraft with a symmetrical airfoil wing, same shape under and above the wing? Lift created by AoA only, to push some air down?

I remember during my training days in flight school when my instructor asked me to explain how airplanes fly. But the thing is, I would explain it to him as if he's a toddler. That was one of the hardest questions I faced in my life

What about angle of attack….What about wings that have no camber? Perhaps a partial explanation in a very good video.

Hello. Do I understand correctly that the airflow on the top of the wing "follows" its shape, because when trying to "break away" from the wing, a vacuum is created between the airflow and the wing?

Can u also explain then why water rises in Venturi effect? When we blow air over the top of U-tube containing water then the pressure at narrow region would be smaller I know but it would be smaller than the pressure compared to WODER REGION OF TUBE ABOVE. Why do we compare it to the air pressure inside the U Tube which I static and say that water will rise up?

Hej! Kul initiativ!! Rekommenderade dej i kommentarerna till 3greens videor. Mycket bra australiensare!

Only need to know three things: the static pressure difference between the top, and bottom, of the wing is what holds up aircraft (dynamic buoyancy); the wing stops flying when the critical angle of attack is exceeded, regardless of airspeed (stall); and a headwind is much more harmful than a tailwind is helpful (fuel starvation).

I have recently started looking more into the understanding of lift. I am not an aircraft designer or engineer but an aircraft pilot and a drone pilot and instructor. While i fully understand your explanation with curved wings, what i am now looking to understand is straight or flat wings, for example a paper rocket or plane. Would be most grateful if anyone could help out. Thanks

I am a little confused. At 5:00, you say that the air is compressed as it moves over the curved surface. But if the air is compressed, doesn’t the pressure increase? So then at position B, the air pressure would be higher than at position A? And then you say that the air under the curve shape expands, resulting in a higher pressure. This doesn’t seem to make sense to me. Can you elaborate?

Hi Captain, which part of your previous video did you made the error?

3:22 If you hold two sheets of paper vertically with a small gap between them, and you blow air down through the gap, the two sheets will clutch. That's the Bernoulli effect. How come with only one sheet of paper the Bernoulli effect is not observable?

One interesting fact: if parcels are being divided by the leading edge, and if camber and AOA are adjusted in order to cause parcels to recombine at the trailing edge, then this guarantees that the Circulation is zero, and the lift is also zero. So, not only is "Equal Transit Time" a mistaken explanation ...it is also a recipe for attaining EXACTLY zero lifting force! Whenever the "phase-shift" between split parcels at the trailing edge is zero, the lift is also zero.

So if lift is created by the curved flow of air over an aircraft wing, which creates a low pressure area above the wing, how do you explain how a flat-winged aircraft flies? What about a wingless aircraft such as NASAs M2-F1? What about the case of the F-15 jet that landed successfully after one wing was completely torn off in a mid air collision? Lift is being created in multiple ways across multiple parts of an aircraft, including primarily reactions stemming from Newton's Third Law.. Provided the sum of these forces match or exceed the total weight of the aircraft, the aircraft will stay aloft. A typical airfoil shape will maximise efficiency, meaning there is more lift created for a given thrust energy. Curved airfoils do create low pressure areas above the wing, and this adds to total lift, but with sufficient thrust energy an aircraft will fly with completely flat wings or even no wings at all, because sufficient lift is created via the body of the aircraft deflecting air like a stone skimming over the water when thrown at the right angle.

Excellent explanation - thank you! When people don't belive that lift is created by a wing pushing air downwards tell them to stand under a hovering helicopter ;)

Circular airflow and Coanda.

Magmar i ask you :::victor schauberger implosion technology wat it is ???

Is the low pressure the lift or is it the turning of the airflow downwards? The change of momentum inducing an upward force on the wing. So the change in pressure toward the centre of the curve ensures the flow stays attached.

Lift is created deflecting a fluid mass. Drag and deflection efficiency can be modified by shaping the surface into an "airfoil". Simplez

With an airplane wing the air is not flowing over the shape but the shape is flowing through the air. In a wind tunnel and with a sail, the first is basically true. We talk about two different interactions here.

I didn't understand your explanation, but I've found a better way for me to understand it. The top of the wing acts like pressure in a large tube entering a narrower section of tube where pressure decreases and the flow is accelerated. The bottom of the wing acts like fast moving air in a narrow section of tube entering a larger section of tube where pressure increases and the flow is decelerated. I would like your evaluation of my understanding of the subject. Am I right?

F=m.a, or F=m.dv/dt; dv is a vector quantity which includes a change in direction, hence lift from curvature. Not the full story, but certainly a significant factor.

Hmm... I've always found the easiest way to "explain" lift to a lay person (non engineer/aerodynamicist/mathematician) is to have them try to handle a full sheet of plywood in a stiff breeze. Makes it really intuitive, especially if you're standing on a roof at the time. The air has mass. On it's way past objects it pushes them around. Now if you want to start creating a shape that has a particular and specific behavior as it moves through the air... that's more complicated.

Helt super forklaring!

Can you please explain how planes with symetrical wing profiles can fly either right way up or upside down.

So put that into reverse: Lift is created by deflecting mass. Drag can be optimised by giving the "flat wing" a profile. A non optimised profile will cause airflow separation and therefore more drag. So keeping the airflow on top of a wing is great to improve lift and reduce drag. Simplez

Both Newton and Bernoulli are still lurking there...

You don't mean that it's all about centrifugal force? I've never heard anyone suggest that centrifugal force is what causes lift.

You say the air speeds up over the convex surface, but why. What is providing the force? Granted if it does speed up, which it does, then the pressure drops. But where is the force causing this acceleration. Your explanation is incomplete.

At 8:28, I think you cannot assume the density of air to be constant. It certainly is a function of velocity (and pressure). Therefore, the equation cannot be integrated without considering density as a function of v. Can someone confirm this?

A flat plate in a stream, if it presents an angle with the stream, also generates lift. This explanation, which relies on a curvature, does not allow to explain that.

Hello Magnar, I'm a university student in an aeronautics course doing an assignment involving correcting and/or fleshing out explanations for lift. This explanation is excellent and probably the best youtube video I have reviewed for this assignment. I was pleasantly surprised to hear that you actually were informed by Babinsky, one of the academics my class discussed in learning about the intricacies of airfoil lift. I thought your video summarized his paper well and even explained some of his points more clearly and concisely than the paper did. I just wanted to add one or two points to add my knowledge to what you explained in the video. Firstly, I wanted to clarify what the Coanda effect is as the paper is a good demonstration of this but I thought some people could be led slightly astray by its use here. While the pressure gradient caused by the curvature of the air flow does likely contribute some to the observations Coanda made his research was very specifically about powered jet flows attaching to convex surfaces. Unlike in most explanations for lift of an airfoil which ignore viscosity as the bulk of the math on lift still holds even without viscosity, the Coanda effect does critically include viscous effects. The reason this matters is that a powered jet generates a lot of turbulence which mixes and draws in the surrounding air to sustain the flow and as the jet gets closer to a surface it draws out more air than can be replaced generating a vacuum that suck the jet to the surface. This is a similar effect to your description of why airfoils have lower pressure on their upper side but critically different due to the importance of the mixing of air due to viscosity. Secondly, I just wanted to mention as it was a point of emphasis in my education about this, the velocity and pressure should never be treated as a cause and effect, this is not a mistake Magnar made but one that anyone attempting to explain lift correctly should avoid. The pressure and velocity changes happen together, codependently and at the same time, like an ice cube melting and your counter getting wet, they're related but happening at the same time.

a piece of plywood in a moving airstream will lift if any upward leading edge angle is introduced

The How do wings work? Holger BabinskI article is behind firewall☹️☹️☹️.

What if I have symmetric or flat wing? Just like aerobatic aircrafts have?

1:07 Why this and not this one 1:09 ? The first image dont show the thurst. just the flow of air. the air from above dont give any thrust. Only the air defelcted from under wing give thrust. Why we should take in consideration the air from above? is because the vortice?

I would ask how such a wing could fly upside-down. My take on it is at take-off roll a wing has leading-edge flaps extended downwards which has the effect of thickening it. At V1 the air can't get out of the way quickly enough and gets bounced upwards. But it then comes back down again because of the weight of the atmosphere pushing down on it. This has the effect of creating a vacuum above the wing otherwise known as a 'shock wave'. Vacuums have to go where vacuums belong, to the top of the atmosphere (equilibrium law). All trillions of tonnes of the atmosphere pushing the vacuum upwards, but practically it's just the air immediately around the plane which does the job. I've seen these shockwaves above the wings of planes as they say, landed at airports with condensation forming along them. At higher speeds above 400 knots maybe, the shockwave starts to have difficulty keeping up with the plane and drags back on it. Engineers eliminate much of the drag by angling the wing back into the shock wave. This 'sweep angle' can tell you the rough operational speed of the plane. When a plane breaks the sound barrier the bang is caused by the shock wave, no longer able to keep up with the plane, collapsing or imploding. A thick wing will create more lift than a thin one but also more drag.

@Fly with Magnar ok. I am interested and I and watched your video more than once. I like your explanation of "pressure" difference. There are however, 2 things that still give me "question". I have 2 observations for you. 1.) I tried your experiment. I confirmed your results. BUT, I also blew on the underside of the paper and it moved up. It didn't matter top or bottom, the paper moved up. Why? 2.) a sailboat's sail is like a piece of paper. It is thin, etc. The length wind travels over the "front" of a curved sail is practically the same as the length traveled on the "back" of a curved sail. The fastest a sailboat will sail is straight downwind where the full area of the sail is exposed and curve in the middle. Think about that. Why does everything on a sail with regards to cause of pressure difference change just because an angle was introduced? How sure are you that "angle of attack" is not more important than curved shape? What are your thoughts? What experiments with paper can you think of to help? I am probably waaaaay out of my league here, but I am honestly curious. I do sail, and as I sail downwind I think about these things.

I used to hate the drawings showing the airflow being forced to go faster across the top of the wing and then joining up with the slower flow under the wing, my brain used to ask how the hell do the individual "packets" of air above and below the wings know how to combine again after the wing has functioned. Quantum physics maybe?

Great work as usual Captain, but if your audience are mostly pilots not design engineers, so they better stick to the angle of attack principle, as in fact all the controls works the same way, i agree the lift is the product of all these things together but it is easier to visualize the deflections in controls in anticipation of the effect than using the deflection increase method. Keep up the good work capt :)

I always had a bad feeling about the bernouille principle theory.

The reality of flying is not just lift, it's the lift vs drag ratio.

You should know that, in aerodynamics, they apply the Bernoulli equation with potential flow. That means the flow is inviscid, irrotational and incompressible. This leads to the Laplace equation with the boundary condition there is no flow normal to the lifting surface. When you blew the paper vertically, there existed flow normal to the surface, so, it didn't meet the boundary condition for aerodynamic external flow. In short, your proof is flawed from the beginning. The Bernoulli equation is based on the principle of conservation of energy of ideal fluid, so, it is the same thing as the Newton's law of motion. We need to know their fundamentals before using them though.

feel vindicated .. back in 2000 i was taught the old theory in school and i had a debate with my teacher about the illogical explanation of why the air over the top of the wing meeting the bottom air at the same time doesnt make sense at all

Nothing wrong with admitting a mistake. It takes courage

Take off is Bernoulli while landing is Newton.

Just a note, "deceleration" is incorrect. It is always called acceleration, simply because acceleration is a vector, so it has magnitude and direction. Like the difference in speed (scalar only) vs velocity (movement with direction)... The same goes for electric circuits, there is NO CURRENT FLOW, only directional movement or jostling (oscillation) of charge (DC vs AC). Hence current NEVER FLOWS, current is a form of flow AND thus, CHARGE is what moves. Current flow is nonsense, can a flow flow? (second derivative of what??) In the same sense, acceleration is the ONLY term and when a car, for instance hits the breaks, it accelerates to a HALT. Because the acceleration vector changes direction to oppose the motion, via the breaks and friction exerted on the road.

Hahahaha....Magnar, your confidence in "airflow !" is amazing. But think again, nothing actually flows, the air is static !!!!!. And let me amaze you even more....try explaining bouyancy... :)

My explanation: A curved wing is interrupting the air-pressure over the wing in a narrow area causing lift.

I've never heard a good explanation of how a fully symmetrical wing can produce lift based on Bernoulli principles. A half symmetrical wing is always shown in the standard explanation and talks about high and low pressure. Doesn't make sense. As in any fluid system, the object must displace more fluid to float or fly (PLANE). An airPLANE wing merely displaces air from the wing to overcome the weight of the aircraft. The angle-of-attack allows the wing to displace enough air off and down from the wing to produce the lift. This is what "lifts" a boat moving through the water i.e. when it gets up on PLANE.

In 7000 hours of flight time. Flying cargo for a living, flight instructing, flying ultralights, powered parachutes, and kites. I have come to the conclusion there is not just one answer. Lift comes from pressure, that pressure can come from impact, ie angle of attack, In a powered parachute or kite. Or from Bernoulli’s type of lift. Some aircraft such as the stol planes could fly with no airfoil at all. Just off impact pressure. There’s a lot more to this, like aspect ratio, And drag curves. It’s not that easy of a thing. Nice video. But the whole story has to many answers.

You stick a plank out into the breeze as you drive along, you get lift. It doesn't have a curved surface but doesn't need one. Its still causing the curve or acceleration of air mass downward. Bernoulli gets too much credit for what is really just a special case of the coander effect. His equation only relates to a stream or venturi but that's really just an aerofoil curled right round to join itself. Coander is all you need and you accelerate any mass you need a force. The force of air moving downward is equal and opposite to that on the wing seen upward. I can believe that in flying syllabus books you still see bernoilli and the equal transit nonsense, I don't know why because its far less intuitive as well as wrong.

So it's Babinsky now, not Bernoulli....

The problem with this explanation is that it doesn't explain how planes can fly upside down, and how some wings are completely symmetrical and even flat in the case of some fighter jets

It seemed like an arbitrary decision to compare lift to low pressure cyclones. Why not compare lift to high pressure systems? That would make the pressure highest in the center of the system and lower as you moved outward, reversing the conclusions of the discussion

Yeah Babinsky is wrong. It is not the curvature, it is the reduction of the sectional area of the streamline when there is a physical obstruction of the wing in the free stream. In theory, the streamline geometry would be symmetrical, causing symmetrical pressure distribution, and zero lift possible. However, boundary layers and BL seperation exist in nature, thus allowing a wing to alter streamline geometry to allow net lift.

I would like to read Prof Babinsky's paper, but your link takes me to a paywall.

Lift is just pressure differential at work. Thats it

magnar, from reading the comments it appears you did not "clearly" explain lift. people once again think planes are being "sucked" up into the sky-

If a slightly inclined hydrofoil is pulled through liquid helium, no transverse force is generated. If the same hydrofoil moves through liquid sodium, with exactly the same geometry or kinematics, then there will be a transverse force, also known as lift. Explain that !

A teaser to explain the difference. An airplane carrying a plane load of bird cages with birds in them. Does the airplane weight less if all the birds fly around there cage? No, because the air coming off their wings goes down and hits the floor and the airplane is still carrying the bird flying or sitting on the roost. If ceiling and floor of the aircraft body are cut out so you can see through the airplane and now the birds fly around their cages does the airplane weight less? Yes, because the bird wings pull the air down throught the open ceiling of the airplane and push the air out the bottom of the open floor of the plane. And if you put in a large fan as in a F-35 and open the top and bottom door and turn the fan on then the airplane can move up without the lift from the wings, because the fan, like lots of little birds, is moving air down.

Aha!

We must respect the old days teachers, but we must not warship them, if their findings are wrong, comparing with modern days, technology, hope aircraft makers find the correct way to minimise the drag, n make more efficient aircraft to save more fuel, to save our planet from Carbon emissions. ❤ From Sri Lanka.

Well, I guess I'm wrong.

Rockets also work on the Bernoulli Bernoulli principle. This is why rockets cannot work in the vacuum of space.

So, in other words, a curved surface in motion produces a pressure gradient across it - low pressure immediately above & a corresponding low-pressure immediately below - as you ABC diagram deftly demonstrates (which, seems a tad Newtonian, wouldn't you agree?). Seems to me all theories, more or less, point to this same conclusions, just explained from a different perspective. Moreover, you're ignoring the role of angle of attack & the Coanda effect at the boundary layer, both of which are highly significant in the generation of lift, wouldn't you agree?. In fact the diagram of high-lift devices you used in order to demonstrate increased curvature shot you in the foot a little as they portray slats & slotted-flaps (curvature/area increasing drooped leading edges & Fowler-flaps would have been a better choice). The primary role of a slats is to re-energise the boundary layer on the upper surface of the wing - not to increase curvature. These allow the plane to operate at a higher AOA, thus generating greater lift at low-speed. Although slotted flaps do increase curvature they, primarily, exploit the Coanda effect by accelerating air through the slot formed between the leading-edge of the flap & the trailing edge of the wing.) This allows them them be lowered to a greater AOA (thus generating more lift) without stalling when compared to a plain-flap. May sound like I'm picking here, but you're being a little forthright, maybe even pedantic, in your explanation ("wouldn't you agree?") so inviting scrutiny. Remember, the devil is in the detail. Wouldn't you agree?

IMHO The Coandă Effect (From Henri Coandă, Romanian scientist, 1886-1972) is more about the property of a flowing fluid to stick to a convex surface* (that precisely addressing and explaining the experiment with the paper). A consequence is "suction", ground effect and, ofc, the so-called AERODINAMYC lift, exerted on a single curved surface, as you wonderfully explained. Bernoulli's Law (from Daniel Bernoulli, Swiss scientist, 1700-1782), on the other side (in conjunction with Newton's 2nd Law) better explain the wing (but not how an aircraft flies, which is a conjunction of factors!). Bernoulli's wing: Simply put, the wing splits the air into two streams, one flowing atop the wing, and one below the wing. One can imagine the air particles A and B flowing together, hand in hand, being separated at the leading edge of the wing and happily meeting again at the trailing edge of the wing. "A" travel on the top of the wing, and "B" below it. That means that they traveled the respective distances, while separated, at the same time (!). And how "A" in "B" stays closer to the surface and just not go away? Well... (*) That's the Coandă Effect :) If the top of the wing is more curved (as a usual wing is), the distance traveled following that surface is, ofc, greater than the "route" below the wing => the velocities v of A and B must be different in the way that v(A) > v(B) (d = v*t, t being the same here). Bernoulli's Equation: P(x)/rho+g*z + v(x)^2/2 = constant. rho (fluid density), g (gravitational acceleration), and z (elevation) can be assumed as being (quite) the same and neglected, thus p and v are inversely proportional. (btw Your equation looks a bit odd...). Measuring pressure instantly and having V(A) > V(B) as explained => P(A) must be lower than P(B) => differential pressure, acting upwards ("lift"). PS there is a trivial question, asking that if the more curved upper surface (Bernoulli) and/or higher pressure to the apex of a curve (Coandă) explains the ”lift”, how a plane can fly inverted? Actually, they can't unless they are fitted with specially designed wings and geometry, as in the case of aerobatic aircraft, or some of the military.

Two pieces of paper hanging parallel to each other, straight down, about an inch to two inches apart, blow in between them cleanly and they will move closer together. Hold a single sheet of paper about an inch from your chest, without bending on the short side ;), and blow straight down your chest, the paper should move towards your chest. An air compressor with a hose attached to the cap of a metal oil can, with the cap open to the can from the hose. Turn the compressor on and the air iside the can will move towards the airflow reducing the pressure I the can which will be crushed by the ambient pressure. Place a piece of paper on the back of a box fan, it will stay there. Etc...

Dear Magnar, these explanations of lift always descend into nonsense in the comments. Newton or Bernoulli based explanations are fine by me. There is no perfect qualitative explanation of lift and we certainly aren’t going to get into Navier Stokes here. From the pilot (and perhaps even aeronautical engineer) perspective I believe it is instructive to root this discussion in the general lift equation of L = CL q A. Lift being ‘force’, this equation must be a form of Newton’s second law. But ‘q’ is the main term in there. This fact is a big clue that the concept named after Mr B, is fundamentally bound up in this. Or, to put it another way, nobody seems to argue against the airspeed indicator as an application of the Bernoulli Principle. And yet when the exact same output shows up in the lift equation, a lot of people have a hard time accepting it. But we shouldn’t concern ourselves too much with those who don’t wish to see.