As an ex Boeing engineer (from back when they were still a good company), I agree with you 100%. But when you conclude your discussion about Bernoulli's Equation and Newton's Laws of Motion with "BUSTED", some people might get the impression that both Bernoulli's Equation and Newton's Laws of Motion are BUSTED -- that is nether are useful in explaining lift. This is obviously not what you said or intended, but I see a lot of room for confusion. I like to say that arguing if lift is better described by Bernoulli's Equation or Newton's Laws of Motion is like arguing about how a bicycle is propelled. Is it your muscles that move the bicycle forward or the tire of the bicycle pushing against the pavement? It's a silly argument, both are true but each only explains part of what is happening. Which description is better depends on what you want to learn about the bicycle. It's also worth noting that the Navier-Stokes equations give a full description of fluid flow, including lift and drag, for Newtonian fluids (air and water are close to being Newtonian fluids in many situations). But the Navier-Stokes equations are generally unsolvable, and they are not exactly easy to explain. Thus they often aren't very useful for things like explaining why airplanes fly or even designing airplanes. Many of the "theories" of lift (Bernoulli's Equation, Newton's Laws of Motion, circulation theory, etc) come from engineers substituting much simpler equations for the Navier-Stokes equations. The advantage of this simplification is that these equations can often be solved, giving meaningful results. But there are huge drawbacks. The simplifications often mean the equations give accurate results only under very specific conditions. If you try to use them under other conditions, then you may get very unrealistic values. Personally, I prefer the Newton's Laws of Motion as a simple answer to the question "why do airplanes fly" -- they fly by pushing air down. For the subtly different question "why do wings produce lift", or "why are wings shaped the way they are", then it's probably good to bring in Bernoulli's Equation. But any time Bernoulli's Equation is used, I think it's important to note that the shape of streamlines or stream-tubes is different than the shape of the wing surface. This difference in shape is important in applying Bernoulli's Equation to things like flat wings and inverted cambered wings.
@synergy6294 Zone theory fails as wind tunnel tests can demonstrate. The fluid pressure ahead of the airfoil is not appreciably higher than behind the airfoil. Similarly, the region of lowest pressure on a conventional airfoil is over the more curved section. The net lift force is generally up and forward, not up and back; again, this can be shown empirically with wind tunnel tests and pressure measurements in flight.
@synergy6294 Maybe you should start at the beginning. Realize this isn’t zone theory. A variational theory of lift Published online by Cambridge University Press: 06 May 2022 Cody Gonzalez and Haithem E. Taha
Thanks for a generally quite accurate video! Some, pretty petty comments from an aeronautical engineer, however: 2:18 Bernoulli's law can be deduced from Newton's laws of motion (and conservation of mass for incompressible flow typically shown in basic education) but not vice versa. Therefore they are basically the same thing, Bernoulli's law is just a special case of Newton's laws. 4:08 Generally correct, but at very high altitudes (or low air density) the air molecules are far between and molecular flow generates lift (and drag) mainly by air molecules colliding against the wing's or lifting body's, such as re-entry capsule's bottom surface at an angle, while the top surface is effectively in vacuum. 6:15 Flat wing *does work* with any wing loading. The flat plate profile's drag is larger and maximum lift smaller than for any sensible wing profile. Thus, dynamic pressure (velocity) or wing area must be higher to get airborne with similar airplane mass. With high enough thrust or wind pressure even barn doors, cows - or fighter airplanes - will fly, though, even without deflected flaps 🙂 The reason why wing profiles, often curved (or "cambered") are used instead of flat plates is their much better performance (and also structural thickness needed for strength reasons). Compare old wind mills with flat plate blades vs. modern wind generator blades. Both work, but with vastly different efficiency.
'Generally correct, but at very high altitudes (or low air density) the air molecules are far between and molecular flow generates lift (and drag) mainly by air molecules colliding against the wing's or lifting body's, such as re-entry capsule's bottom surface at an angle, while the top surface is effectively in vacuum." Is it not true that you are distinguishing between, in the case of sailing for example, lift sailing and drag sailing? So, it's not about the density of the medium but the orientation of the relative flow and whether it is conducive to a pressure drop "on top" participating in greater proportion to the higher "drag" pressure on the bottom? Same situation with a traditional drag parachute vs a modern lift producing parachute?
@@davetime5234 Lift sailing is like flying with unstalled wing, generating large lift, while in drag sailing, the wing is stalled, generating mostly drag. By definition, lift is the force acting perpendicular to the incoming flow and drag is the parallel force to the flow. The sailing and parachute types are distinguished between their major force of action that is being applied. For a lifting wing, the static pressure drop on the top surface can be many times higher than the pressure increase on the bottom (compared to ambient pressure), but the pressure drop on the "top" surface is significant even for a completely stalled wing (or plate). For example, a long, flat plate perpendicular to the incoming flow has pressure drop on the leeward face almost equal as the pressure increase is on the wind side, effectively doubling the experienced force when compared to situation with only "bottom" surface's static pressure increase would be considered!
4:08 Go back and look at the diagram at 1:44. The high pressure on the underside of the wing contributes a substantial proportion of the overall lift. On some wings it approaches 50% of the overall lift. When a wing stalls, the upper surface contribution goes away and all that is left is the lower surface component.
@@ronaldjensen2948Pressure distribution depends of the angle of attack. For example, at zero angle of attack, a symmetrical profile has similar underpressure on both top and bottom surfaces, resulting zero total lift. And at some negative angle of attack, the profiles have larger underpressure on their bottom surface than overpressure on their top surface. That creates negative lift, making inverted flights possible 🙃. And no, the top surface of a stalled wing doesn't lose all its underpressure. Just a large part of it.
Thanks for this! I always like to point out that spoilers are on top of the wing. If the top of the wing didn't matter, then all they would do is create drag, not kill lift.
Another way to bust the "blow over the paper" experiment "supporting" Bernoulli's law is to let the paper hang freely downward. If one now blows down next to the paper, nothing happens. As an effect has to be independent of the position, rotation or daytime, this experiment should still work. I had to learn, that Bernoulli's law is only valid along one of the "lines" over the wing. Thank you, thank you, thank you for the video and time putting into it. There are too many wrong theories about planes flying, even in schoolbooks.
You didn't blow hard enough. It works if you hold the paper straight, without any curve. It wouldn't do that if Bernoulli's principle didn't always hold true. The 'lines' you are talking about are actually sort of waves, so you're not wrong, it's just slightly different. The waves interact with the wing, in a way similar to a beach surf. If all you can see is the beach, the assumption that where there is no surf, there are no waves is easily made.
Regarding the Coandă effect, Boeing built two YF-14's using this feature (failed to get the final bid) while the Soviet Union went ahead with a production version, the AN-72. You used the F-104 as an example of a plane using a flat wing when (even with the leading edge and flaps stowed) it does not - although very thin and symmetrical (I think, it looks so). One youtube video claimed that we have not really come up with a good theory on lift; it seems to me we have several things going on and depending upon angle of attack and speed one of them will over come the others. Something is working as we keep making things that can fly. :^) But the way lift is taught in your lower grades is not the only thing tossed in the trash once you get into college. I'll offer up the atom as another example.
Ah just flip your aircraft upsidedown and reduce throttle! Your Drag will become your thrust vector and the gravity vector your lift. It's that easy to fly forever! 😆 Now for the big question: Why would you design a tear shaped wing with the underside bulging outward like in one of your graphics. The downward forces will subtract from the upward ones! And then you have stuff like the Prantl wing ;) You could also do a video on stall patterns of different wing shapes (and please include negative swept wings). Such a wondeful topic. I'm all for the magical pixies theory. Cheers
So many people discuss "new ideas" for a problem for which the mathematical model was found before 1850 by Navier and Stokes. They improved the previous equations by Newton and Euler to include viscosity and thermal conductivity of the fluids. And I don't mean Newton's laws of motion, but Newton's differential equation for what it's called now a "Newtonian fluid". Newton already considered the speed of sound and Euler also the thermodynamics of the fluid, one century before Navier and Stokes, and none of these are reflected in oversimplified models you busted, even if we all saw nice photos of supersonic fighter jets with vapor cones behind them. If you need a simple reason for lift, use Newton 3rd law of motion: if you push the air down, the air will push you up. If doesn't matter if you do this by flapping your wings like a bird, with a propeller like helicopters or using a wing and relative motion of the air, like planes and kites. Very good and compact video, well done! I would suggest another one about the stall which is even less understood. Most can't fly a glider and feel it with their own hand, but you are very good at explaining.
That fairy tale of two air molecules trying to meet again, after one goes on top, and the other below the wing, that story is sooooo weird. Just ask HOW a pair of air molecules could DO that. It is most unlikely the two would even meet again. Again, ask yourself HOW, and try really hard to answer the question. You can't! It is nonsense. Then, why did people believe it? Then, why would this fairy tale be the reason for a difference in pressure and speed? When a neighbour pair of air molecules split, no problem, that can happen, but them meeting again is a huge problem, sure it is possible, but it is also possible one of them is there earlier, why not, and still, there can be our pressure difference. Why on earth did people start believing these molecules have a date behind the wing? People are weird.
??? Nobody said the molecules "met" one on one . The airflows just reached the trailing edge at the same time. Which sadly is untrue, because it did simplify things from an intuitive perspective. Try to define lift for real in a couple easy to understand paragraphs. Good luck.
@@maca5645 - Um,,, read the first sentence of the OP… that is literally what he said. Oh,,, the answer is money $$$; all aircraft are held up by large quantities of cash. Going faster takes- more money^2… 😎
It’s only logic to believe there is a high pressure under the wing, and as a result there is a low pressure over the wing, reguardless if the wing is curved or flat.And no the two streams don’t come together at the same time.
Sorry, but i want defend Coanda effect to explain lift. My definition of Coanda effect differs from your: my definition is : when a solid ojbect is immersed in a fluid (ie: water or air) the fluid tend to follow the profile of the object. When a plane start to roll the air touches the wings and follow the wings' profile. In this way the air is pushed downward and for Newton's Third Law: Action & Reaction this air down causes the plane go up. It's like a baloon full of air: when the air exit from baloon the baloon travels around
Crackpot theories abound regarding all kinds of topics. You should see some of them attempting to explain relativity. And the insane idea of a perpetual motion machine never dies. Combine scientific illiteracy, and maybe actual illiteracy, with the ridiculous idea that everybody is entitled to have an opinion and be listened to
Oh it's so easy to stir discussion in aerodynamic circles ... Just consider KF airfoils for example, or any low-speed airfoils in general ... those are magic, still after 4 decades or so since Drela released XFoil ...
First I would like to congratulate this channel, not only as one of the very few that get lift right (see previous videos), but also for explaining it well. I would still like to comment on a few points raised in this video that might merit deeper discussion. Air should be treated as incompressible at subsonic speeds, just indeed like water. There is no significant change of air density around a subsonic airplane. Looking closely, submarine control surfaces and hydrofoils lifting hulls out of the water at speed follow exactly the same physics as airfoils. This changes drastically only in trans- and supersonic scenarios, when very steep density gradients, aka shocks, develop. This change is actually the reason why supersonic airfoils are so very different. Any design can be optimized for either regime, but impossibly for both. This issue gave rise to, e.g., swept (edit: variable sweep) wing designs, but is also the reason why the Lockheed F-104 was very difficult to handle at subsonic speeds, and why supersonic airliners would only be viably efficient when they could stay supersonic for most of the flight time. About the Bernoulli law, it is helpful to look at it as a one-dimensional limit of the full 3D situation. Expressed in this way, it relates the pressure gradient along a flow line with a force, and thus acceleration, along that flow line. This of course does happen above and below the wing of an airplane, but it is irrelevant to the question of lift. What is relevant is the pressure gradient perpendicular to the flow line, which is equivalent to a force/acceleration in that direction. This is the lift. This is, as will watchers of this channel know from previous videos, equivalent to the curvature of the flow line. In short, it is the curvature of the flow lines that creates the lift. A slab as lift creating surface can, to some limited degree work. The relevant curvature is exclusively at the four edges in this situation. The point is that if the flow was laminar instead of turbulent, i.e., symmetrically identical at the front and back end of the slab, it would not create any lift, just torque. The "secret" why it does create some lift in real air is that at the back end the flow detaches from the slab surface straight and barely curved, instead of following the edge, as it is forced to do in the front. This still creates torque, is inefficient, and the stagnation point of the flow is barely controllable, which should make it a nightmare to fly. One of the breakthrough achievements of early aviators was to make the stagnation point controllable by blunting the front edge of the lifting surface, so that now the split of the flow could be controlled by angle of attack. Finally, Newton's laws: Actually, this explanation in its narrow form, as it is almost always presented, would violate Newton's first law. The downwash acquires downward momentum, but a plain in level flight does NOT acquire upward momentum. So the momentum of the downwash has to be compensated somewhere else. In order to understand this, and actually the complete package of all three laws in relation to flight, one has to take a huge step beck and consider the entire height of the atmosphere and its boundary conditions, (hard below, soft on top) around the airplane. A plane creates a huge, albeit very weak and geometrically diluted vortex, with itself in the center, that ranges from ground level into the upper atmosphere. It would also be the force that vortex exerts on the ground that is relevant for lift, if one insists on using Newton's laws to understand it.
We can compare an airplane moving "over" a mass of air with a ship moving over a mass of water, ignoring the physical differences between the two elements for now. The ship does not sink, whether moving or stationary because of hydrostatic thrust. For the airplane to achieve a similar effect it has to create a "surface" on which it can float. It can only do this when moving and by the shape of its wings. Regardless of the shape of the wings, it will "sink" if its speed is reduced to zero. But why doesn't the ship sink, even when stationary? Because of the shape of its hull (which acts as the wings of the airplane). So, what would be the ideal shape for the airplane's wings so that it floats, even when stationary? Would having the fuselage in the shape of a hull (so that it doesn't sink when it lands on the water) and the wings concave at the bottom, as if it were a huge umbrella, solve the problem? Yes, I am ignoring all the aerodynamic issues, as I know nothing about aeronautics. I am just wondering. A helicopter in vertical fall creates a bit of this umbrella effect, as the friction with the air during the fall keeps the blades spinning.
@@MarkxTube Celsius, millibars, meters, Mach, etc. Knots is not imperial nor metric, and used in metric countries. Zulu time is also not metric, but used in all metric countries. Many units and terms in aviation come from France in fact.
5:10 help me out here. The wing(underside) is still producing lift but less of it after the stall. Wings still create lift after the stall as you can see in the graph. I’m happy to be corrected and thanks for sharing, I found that so interesting.
When a wing stalls, almost lift over the wing (approximately 75%) is lost in an instant. The stability of the aircraft will determine wheter the aircraft will enter a dive, drop a wing (one wing stalls before the other,) or the aircraft will enter a deep stall, which in most cases is unrecoverable.
a stall is a reference to an item failing to do an intended action. like a checkout counter with a customer problem. The curve over the top is where most of the 'lift' is generated. A stall is that 'lift' not being generated. The other aerodynamic items are as before the stall... and are likely to change soon.
Thank you for the excellent compilation. What researchers of flying fish would you suggest I follow? I want to build experimental gliding models of similar mass and flexibility of materials approximating that of a live fish for open air and wind tunnel study. I specifically refer to the four winged or finned flying fish such as the California. If you also think these animals are remarkable, I would be interested in hearing your thoughts as well.
competing water to air is closer if we compare supersonic air flow. because basically every movement on weather surface is faster than surface wave speed.
Actually, it does work if it's a narrow strip of tissue paper hung from the lower lip and one blows straight ahead - I've done it. Looking at wing loading of a Cessna 172, one discovers the pressure differential required to support the gross weight of the aircraft is on the order of 0.1 psi
Magnar unless you are over 70, the "hangar flying" topics of the days when I began taking dual in Champs and J3s included the "Lift" arguments, before your were born. I'm fully confident the same were taking place well before my birth also. These are the ephemeral subjects which are the essence of the time-honored sport of hangar flying, and subjects which will always be with us. Most of the favorite discussions over the years seldom involve all the elements of physics which are in play. One of my favorite topics for which much has been said and written since I got my first motorcycle some 50 years ago when I lived in Japan, is that of "steering" the bike at speed. Most of the arguments on that one totally lack the most important principle of conservation of angular momentum. But then, as a practical matter, I don't think any of my grade school peers had taken courses in physics when we all learned to ride our bicycles. Aeronautical engineers and designers have happily been using the ubiquitous lift equation for reliable wing design for decades also. All I can say is have fun and "Keep 'em flying" as the WW2 ads and war bond campaigns used to tell us.
I remember one thing I did as a young kid. Putting my flat hand outside an open car window. Like it was an aircraft wing. As the car's speed increased, so did the force on my flat hand. Any change in the angel of attack, + AOA would result in my hand being flipped upwards. And this was a strong force acting on my hand. And where did I feel the force the most? On the underside of my hand. With very little force being felt on the top of my hand. So I would conclude that this was the main reason wings generate lift.
Our skin can feel higher pressure better than lower pressure. The pressure difference around a wing is just a few percent of the atmospheric pressure. We cannot feel that. When you hold your hand out of a car window, you are holding the hand in an angle against the wind. It will push on your hand with a force acting upwards and backwards. Is easy to neglect the vector pushing your hand backwards. Therefore, you only feel the upward vector, interpreting it as lift. Your hand can best be compared with a stalled wing.
@@FlywithMagnar Thankyou very much for taking the trouble to comment on this amazing subject. Wikipedia has an interesting page on "Wings", and explains AOA. I use to help launch Glider aircraft, and on windy days it never ceased to amaze me at the lift created by the wind blowing across the wings. Kind regards, and greetings from Africa.
A wing is just a very efficient shape at deflecting the air downward, which happens not only at the under side but also the upper side via manipulation of pressure. This down draft tells us there must be a lift force induced on the wing because of newton's 3rd law of motion.
@@chengong388 Nice explanation for an average Joe. All the rest of discussion about how the lift is actually generated becomes quickly too hard to explain in easy terms.
Positive cambered airfoils with flat bottoms still produce lift at zero AOA and without air deflecting. This case shows the pressure differential is the cause of lift, not the deflected air.
@@Talon19 this wing will produce a downdraft because the air flowing over the wing will, because of its momentum, not change direction. Therefore, Newton's third law of motion is still walid as an easy explanation for lift.
6:42 onwards: The F-104 has a sharp leadning edge. The wings are optimized for supersonic flight. But the stall angle is low. Therefore, the wings are equipped with leading edge flaps and trailing edge flaps, as shown in the video.
if you think air is like ground or ice, you get the idea, why ground keeps you up, and you dont fall, it pushes you back up, when you push down to it, all forces must be equal to maintain level, of flight
I hate academics rules of how things need to be presented. yes you. dont waste your time in this video. opposite forces are equal. air must apply equal force to the wing as the wing applies to the air. if air does not hold you up, you fall. yes tree leaves fall very slowly, like a parachute, no side-ways lift. because air holds you up. explain that pro. when you push a wing piston down to an air column, stuff happens. when you push a wing piston sideways to the air, like a sail, stuff happens.
p=F/A = mg/A, so literally making a plane lighter and increasing wing surface area, will increase the wing pressure to the air, during flight. all other factors are minor tricks. of course F is a vector force, so during flight it points mostly forward and a bit down. no, it points still directly down. as much pressure you push down with the wing, the equal force air pushes the wing up. of course when pushing down, then the above wing surface experience the decrease of pressure of same magnitude. wing functionality is equal when moving and when free falling. or tree falling leaves.
Thanks. Now do you think you‘re able to explain the Magnus effect causing lift on the Flettner aircraft which has cylinders as wings? Benouilli and air pressure below and above that spinning wing does not seem to explain the lift force. Rather, it looks like the relative speed between airflow of the surrounding air and the spinning cylinder surface matters. Compare with topspin and backspin in table tennis. I believe flow separation and deflection of air around the cylinder matters, and only Newton (actio=reactio) not Benouilli, explains the lifting force. It even seems as Benouili would partially antagonize Newton when it comes to the Magnus effect!
@Tekemon-nztfd The Telekom website doesn’t have any actual sources or evidence. If it did, you would be able to provide that evidence or source here, or be able to provide better direction than “check the post on the website”. You aren’t making a good case for yourself or your claim.
@Tekemon-nztfd 2. The flow is separated at the most forward point on the airfoil; wind tunnel tests show this empirically. You can see plenty of them in my “Aviation” playlist. Free ebook please.
@Tekemon-nztfd 3. V1 is an arbitrary speed which varies based on aircraft weight, configuration, temperature, and density. V1 is a concept useful for takeoff calculations, nothing else. Free ebook please.
In 1st August 2024 I have to go to Lampang with ATR-72-600 Bangkok Airways. I hope to this flight might be you to be captain in this flight Safe Flight.
It's pure ignorance to talk about "equal time" for air over the top. The camber causes air over the top to pass faster than air under, even before "A" slows and compresses air underneath the wing. Are we to think that for a ram-wing GEV like the Lippisch X-114, air bounces from under the wing imparting lift via Newtonian reaction, off the water and back up and off the wing again? Or is it in ground effect via Bernoulli lift enhanced in GE, until it flies up above GE and switches to Newtonian reaction in the air? Maybe with a propeller or ducted fan, there's a strong component of Newtonian reaction, but not for a wing -not even a flat plate without camber.
Because while the aircraft is subsonic air sometimes isn't. Air over the wing moves much faster than the aircraft and can go supersonic even at mach 0.8
G'day, Yay Team ! I like to compare the performance of Airscrews with laminated wooden Blades featuring Perfect Helicity of Pitch, ALL the way in to the Hub...; Against that of the Pressed Sheetmetal "Fans" supplied with the small Retail-level "Stove-Fans" which use a Peltier Device to convert Heat from a Wood-Stove into Current powering a small DC Motor - spinning the Airscrew, to Suck the Air across the Stove's Hotplate & Blow that heated Air out into the room, all while relying on the relatively cool Airflow thus induced to flow across the Cooling Fins mounted above the Peltier Device...., to maintain the Thermal Gradient which is "tapped into" in order to generate the Current required. There have been, over 5 or 6 years, several iterations of Horrible excuses for "Fans" released for sale, first were the Constant-Pitch Flat-Plate "Aerofoils"... Then came Slightly-Cambered Flat-Pitched units..., with successively more efficient Hot/Cold "Sinks" which have steadily improved the output of the "Powerplants" - while the "Fans" were horrible. And this Winter (in Australia) has revealed a type of Fan with a strangely Cambered Single-Surface "Semi-Helically" pitched Blade-Section...., which has taken me a while to observe and comprehend. As a Tool, I use Dust-Particle Accretion-Patterns to effectively visualise the mapped Barometric Pressure all over Both surfaces of the working Aerofoils. To speed the process, I set a "Dhoop-Cone" type of Incense smouldering "upstream" of the Stove-Fan, and after about 20 hours of operation...; the Hot Ash-laden, Smoky Combustion-products, together with the Cool(er) Vapourised & recondensed Resin "Smoke" flowing through the Disc has left a precise visual Footprint of the Boundary-Layer Air-Pressure, reflected by How much and/or how little Dust Accretion occurrs..., Where, precisely, On the Rotating Blades - as the High-Pressure smoky sticky dusty Air is being Squeezed by the passage of the Blade going through it...., Or NOT. Because wherever the Low Pressure Zone exists, the Surface accumulates very Very VERY Little in the way of Dust Particles accreted by Contact with the Air... Double-Surface Helical Aerofoil-Section Propellers accrete Dust from the Underside of their Leading Edge - thickest on the first 50% of the Chord - with almost zero Dust-Accretion on the Upwind Side - and the Accretion demarcation-line along the Leading-Edge is Razor-Shaply defined. The Single-Surface Sheetmetal Units feature Press-Cut Edges, with 90° Corners and a little Flat Perpendicular Face, as the Actual Leading Edge. Air is struck by that Flat, and bounced off to either side - leaving Dusty accretions on the Perpendicular Leading Edge. The Air Bounced "Upwind" curves back, attempting to "follow" the retreating surface of the Blade as it sweeps past - but the Front 50% of the Blade is "Flatly Un-Cambered and has maybe 2° of Flat -Pitch ; so a thin "Helical-Spiral Slice of Air" goes "Under" the Leading-Edge, having been effectively "cut off" by the Sweep of the Blade. The Airmass "Upwind " attempts to follow the retreating Upper Surface - but never quite gets there, and from 50% Chord the Trailing Edge is "curled" to effectively "add Pitch-Angle" to the Flow being Compressed Under the Blade's Trailing-Edge.... The Dust-Accretion Patterns clearly Map the Pressures. And, to my Horror I discovered that the Latest iteration generates Retrograde-Airflow, backwards through the Blade-Tips of the outer 15% of the Disc's Radius..., as well (!). Each Blade tows a pair of Vortices, one Shearing along the Trailing Edge as the High-Pressure Air is Spat, or flicked, backwards - with a diverging Vector away from the Air trying to follow the Upper Side of the Blade - as it curls away downstream, as it sweeps past. And, also a vicious little Retrograde-Vortex caused by Airflow being sucked into the intense Low-Pressure Zone, Upstream of the Central 60% of the Disc's Area. So.... It does "work".... Kind of. But it's woefully Inefficient. I guesstimate that if my best Helical Propeller can attain 92% of the Betz Limit (no Array of Rotating Aerofoils can ever convert more than 0.5963 of the Kinetic Energy in the Wind, into Torque in a Shaft, Or Vice-Versa. To extract 100% of the Torque in a Shaft and convert it into accelerated Airflow..., Requires that the Shaft be stopped from spinning. To extract ALL the Energy from the Wind-Column, a Windmill would have to Stop the Wind from blowing. 59.63% Is the Limit of what May be achieved.) So my 92% Efficient Airscrew is achieving 92% of 59.63% ; which is actually only 54.85% Absolutely Efficient. I wager that the latest Sheetmetal Stove-Fans might be 15% Absolutely Efficient, turning about 35% of the little Motor's Torque Into nothing but NOISE. And, here's the funny thing about Marketing Jism...(!), The Consumers Are Attracted to the "Surprisingly Powerful SOUNDING, slightly Aggressive little Purring Noise...." Made thereby. Backtrack me to my Videos to see the various Results. And if you feel like a serious sort of a Giggle (?) Go ye unto my "Personal Aeroplanogy" Playlist, and check out, "National Transportation Museum ; Visiting My First Aeroplane...!" to see what it was that took me for my first Solo (!). An older Video about it is on that scroll too, but it's more of a Slide-Show, featuring Old Photos, & Magazine Articles, to establish the Paper-Trail, & nail down the Timeline, "The 1975, 8-Hp, Red Baron Skycraft Scout...; World's 1st Legal Minimum-Aircraft !" I was it's 3rd owner, I did nothing actually "Pioneering" in it, Beyond being the Last person to have ever Flown the Aeroplane around which Air Navigation Order 95.10 was written, and Gazetted by the Australian Parliament in August 1976. My "Lockout-Index"..., For (more) safely Aerowing Weight-Shift controlled Rogallos Behind 3-Axis Dragonfly-Tugs..., was a far bigger contribution to the Art (Of safely decorating the Sky with Flying Machines....!) ; but being able to visit my first Aeroplane, and seeing it chained up to the Ceiling in a Museum does feel pretty bloody good...(!). It certainly impressed my Children, when they were in Primary School, and we first learned about it ; and made the Pilgrimage (50 miles to the next town down the road) to visit the dear old thing (!). Anyway, Thanks for the Video, I did enjoy it. That # 7 "Zone Theory" Idea was one of the Silliest things I ever heard of. Such is life, Have a good one... Stay safe. ;-p Ciao !
Agree with a lot of what you say. But WRT Bernoulli effect, it’s not correct to say it’s busted. More specifically, yes, it is true there is no “wall” above the wing to enforce a strict Bernoulli channel and its associated conservation laws. However, there is NOT nothing above the wing! There is atmosphere, all the way up to space! THAT is your Bernoulli channel wall! However, it is not a hard wall like a pipe, but rather a soft wall. It does not provide a hard immovable boundary condition like a pipe, but rather a soft somewhat compliant accommodative boundary condition, but a boundary condition nonetheless the less, just like a wall, it will resist air pressing on it (or sucking on it) but, it will give a little and change the boundary condition in the process, but it’s still there, resisting just like the Bernoulli pipe wall… just not as rigid. So the correct way to state this (IMHO) is that there is indeed a Bernoulli effect that in principle is about the same as the regular Bernoulli effect, but it’s not exactly the same because the boundary conditions are different, and because of this it is not as powerful an effect as in a Bernoulli pipe, meaning you need additional lift, and this comes from Newton’s reaction forces from diverting the air flow (momentum change). Thanks for great video!
@@tedarcher9120 agree that is ultimately the case, but it is challenging to explain how 70 to 80% of lift is due to forces acting upwards on the top skin of the wing, without discussion of pressures, Bernoulli and Coanda effect.
@@hu5116 Bernoulli equation does not require any walls. It simply relates the stationary airflow's local dynamic pressure to its velocity in the flow direction.
@@tedarcher9120 In ground effect, you assume that all the incoming air flow ramming under the wing would be forced to flow under the wing. However, in reality, some air deflects above airfoil, increasing top flow's mass flow and velocity while reducing its static pressure.
Since in conventional aircraft designs, the wing is moving and the air is stationary, then any concept with relies on the forward-backward 'motion' of the air particles over the wing (including different speeds over the top and bottom of the airfoil) is baseless. The only components there are to deal with are the relative upward/downward velocities of the previously static air molecules as the different cross section elements of the wing move through the air mass. Counterintuitively a standard wing profile would see more air shoved up than down as it travels to the maximum chord width, which one could expect would give a net downforce, rather than up! Once the wing has fully passed a particular bunch of air particles the net up-down result must be zero, unless angle of attach has induced a general downward motion of the airmass - then thrust (or lift) is mass of air times its downward velocity, I guess. Love your work!
@@nigelwilliams7920 It most certainly can. Fill up a bathtub with stationary water, then move your hand through the water at one end of the tub - is the water at the far end of the tub, despite never coming into direct contact with your hand, still stationary? The particles in a fluid interact with eachother.
@@nigelwilliams7920semanics. One is a laminar flow and the other is a laminar disturbance. Push a stick through a pond, then hold it a smoothly flowing stream. Take a photograph of the water. Compare.
I am an aeronautical engineer who provided some constructive criticism to some specific points in some of your previous videos about lift. For this one, my feedback is this: I am not happy, I haven't found anything to criticize!
@@SoloRenegade ... It doesn't. It SUKS air over the wing. All the CCW planes are pusher props with the propeller at about the trailing edge. The pressure in front of a propeller is lower than ambient. The pressure behind a propeller is higher than ambient. So this arrangement places the wing channel in the low pressure zone of the propeller. An interesting quote from Custer himself: "this is an aircraft which is not an airplane. It does not plane the air to fly, rather it brings the air to the lift surfaces and reduces pressure". In any event, regardless the fact that the Coanda effect, or the CCW effect, CAN produce lift, that is not HOW lift is created in the traditional sense. Magnar is explaining different myths and misconceptions in popular wrong explanations for how a traditional wing generates lift.
@@adb012 nice strawman and cherry pick, suck, or blow, the air doesn't know nor care. the air is moving, and the wing is not, but the airplane flies. Period. You're making the same exact fallacies as the types described in the video with your childish attempt at a refutation. "this is an aircraft which is not an airplane." except it is/was an airplane, regardless what he claimed or felt. What does this have to do with ANYTHING? How does this have anything to do with lift production? Do stay on topic and avoid using red herring fallacies. "In any event, regardless the fact that the Coanda effect, or the CCW effect, CAN produce lift, that is not HOW lift is created in the traditional sense." I know exactly how wings produce lift, and the channelwing achieved it same as other aircraft do. "Magnar is explaining different myths and misconceptions in popular wrong explanations for how a traditional wing generates lift." I'm glad you understand that. Was beginning to think you had no clue. Regardless, you specifically claimed, "I haven't found anything to criticize!" This lack of critique proves you weren't looking hard enough, and lack understanding of such topics, otherwise You would have called him out on this objectively false claim of his at the 7:28 mark.
@@SoloRenegade ... It is not the same to put the wing in front of the prop where the pressure is lower than the atmospheric pressure than to put the wing behind the prop where the pressure is greater than the atmospheric pressure. Even if the air didn't know or care (which is not the case, but it is a good approximation at low Mach numbers) the wing does, especially when that pressure is applied only to one side of the wing. Remember that the lift is the difference in pressure between the upper surface and the lower surface (I am simplifying a bit, technically it's the integral of pressure times the differential of the vectorial area around the airfoil or wing. As for the gratuitous ad-hominem attacks, I am not going retaliate and escalate.
@@adb012 stop cherry picking. the idea is airflow moving over a wing, rather than wing moving through teh air. Clearly this is too complicated for you to grasp. I am addressing what was claimed in the video, not your petty cherry picking. "As for the gratuitous ad-hominem attacks, I am not going retaliate and escalate." my insults are not ad hominems, as they are not part of my arguments. My arguments stand on their own facts. So they are in fact merely insults, not ad hominems. Learn the difference. You talk all condescending, but you're wrong, just admit it. Prop in front or rear of wing is a separate topic of debate. The childishly simple fact you can't comprehend, is the air doesn't know it was being blown nor pulled. And multiple aircraft such as the jetwing and other radical concepts that flew but were not mentioned blew air over the wings as well.
An excellent discussion of the many really misguided ideas about lift. But you are fighting a loosing battle. Your assumption is of people being rational and accepting empirical evidence. People can be severely delusional and married to false beliefs in a tenacious manner. I'm not suggesting you stop your calm and rational discussion of the issues, just don't be surprised or discouraged by the many folks who will not accept the nature of reality.
@@FlywithMagnar I have to admire your perspective. Yes, by all means declare the truth on this in your amazingly calm and rational manner, and if it helps only a few to hold the proper perspective - that is great. My point was only that there will be those who cannot or will not see reason.
@@dboss7239 I've mentioned twice in these comments that academic aerodynamicists appear to insist in large proportion, that the production of lift has not been explained without including viscosity or "dissipation" more generally as absolutely essential to the theory. I'm not saying I agree with this, but it brings up the question: who is being rational? In other words what is the truth in explaining lift. Nasa's website doesn't mention viscosity (or dissipation). But looking at the academic voices and research (these are the people teaching the leaders in airfoil design and use), what are we supposed to believe about the essential explanation of lift? And does this call into question (just being honest) Magnar's explanations or not?
@@Talon19 Vertical displacement of mass is definately required (vertical change in momentum of air). This can only be accomplished by a force: a vertical pressure difference. The vertical pressure difference is caused by the assymetry of the airfoil to the relative wind. The question is whether all of the above requires viscosity and possibly other "dissipation" in order to exist.
@Tekemon-nztfd I'll try 3, 4, and 5. 3. Why is it necessary to accelerate to a certain velocity (V1) in order to takeoff? Lift developed by the wing is dependent on velocity, you can increase the lift generated at a certain velocity by having a more aggressive wing (multi-element wings like those used in Formula 1 cars, and modern high-lift devices like flaps also effectively make multi-element wings to radically increase lift at a certain velocity) but the tradeoff is that drag will increase rapidly with velocity. Airplanes need to generate lift that counteracts weight for most of the transit, and at high velocities, so that these aggressive wings aren't an option for cruise flight. Fixed-wing aircraft need velocity to generate lift. The lift equation is proportional to velocity squared. Helicopters can take off without forward velocity, because the rotor itself is effectively a set of wings, and the wings are accelerated by the engine. This velocity of fluid over the wing is what generates the aerodynamic forces - no airspeed means no lift, and no drag. 4. Why does lift require constant input of energy, that is why does an aircraft need thrust? The airplane itself isn't rising or falling so no work is being done to maintain altitude. A: Thrust counteracts drag, it doesn't do anything directly for lift. As previously stated though, you need forward velocity to generate lift on a fixed-wing aircraft, so thrust is necessary for that purpose, without it, drag will simply slow you down to a stop. The wing itself, along with the fuselage and other components, generates drag. This drag needs to be counteracted by thrust, otherwise the airplane will lose velocity, thus creating the following dilemma: when losing velocity the pilot can either a) increase the angle of attack to generate the same amount of lift, thus increasing drag and further losing air velocity (deploying high-lift devices has an even more dramatic effect on lift and drag), or b) the pilot retains the same angle of attack or even reduces it and simply accepts the loss of lift which will result in a loss of altitude. When airspeed, specifically indicated airspeed decreases, either a) or b) will have to occur, there is no free lunch. There are multiple components to drag, but it's not necessary to know those to simply understand, that in order not to lose air velocity, drag needs to be counteracted by thrust. If you want to know where this energy "goes", it goes into forming vortices and accelerating air particles. To create acceleration, a force is needed. The equal and opposite force to the one that accelerates the air particles we call the drag force, and it will act along the entire distance the plane flies, that is the total work done by the plane - in counteracting drag and thus accelerating air particles. Cars, which don't fly, also have to input a significant amount of energy to not lose velocity. They're also counteracting aerodynamic and, in the case of cars, tire drag also. 5. Answered by 4
The truth about airlift is way crazier than this video suggests. It is NOT POSSIBLE to explain the lifting property in flying by means of aerodynamics. Reason for that is the fact that aerodynamics is not about air. A lot of people would still be alive if pilots would be taught that correctly.
@Tekemon-nztfd I'll see what I can do. 1. A high pressure area is not the natural place for a vortex to go. 2. Sound. 3. You can't commit to a choice you don't have. 4. "Seemingly not doing any work" implicates air is something you can stand on, which I haven't proved possible yet, but I'm working on it. 5. Enigine power is consumed by pushing air out of the way rather fast.
@@Berend-ov8of Your entire premise is bogus. Aerodynamics: the study of the properties of moving air and the interaction between the air and solid bodies moving through it; the properties of a solid object regarding the manner in which air flows around it.
