Lift explained - Bernoulli's and Newton's equations are equally correct, when used correctly 

I am a combustion engineer and private pilot, and I had to be careful in the same way regarding the FAA engine terms detonation and pre-ignition! (In reality light knock by itself is not damaging while pre-ignition is the kiss of death leading to immanent piston failure in the cylinder it occurs in. Although the actual technical meaning of pre-ignition this is aligned with is when combustion in a hot cylinder occurs prior to the ignition spark.) It was funny too when my CFI asked me why maneuvering speed for a given aircraft changes with the amount of weight that is onboard - I couldn't help but blurt out "That means the wings are not the weakest link!" Because the maximum force (lift) the wings can generated at a given indicated speed doesn't change with aircraft weight, but the lighter the weight of the airplane the more acceleration it will experience from that same lift force at that speed. And, since in theory the aircraft is certified to a given fixed G-level (acceleration rate) a lighter loaded plane will experience that acceleration rate with a lower amount of lift force and therefore at a lower speed.

Dude I'm working on CFI soon and I've got a lot of strange looks talking about this stuff!

I always wondered why the keel was so huge. Makes sense now!

Exactly. I'm a sailor too. The rudder plays a role too. It's a brake. Balance the sails and keel forces through proper sail trim and ballast location, and you can steer the boat without a rudder upwind. You'll go faster and take less of a beating if your balance the helm and trim your sails properly. My theory about aerodynamic lift and aircraft wings relates to airspeed, displacement and aingle of attack creating bouyancy as long as airflow remains laminar. How else to explain sustained inverted flight? Bernoili theory says an inverted airfoil will create it's lift vector towards the ground lol. Bouyancy says the shape of the airfoil plays a small role relative to airspeed, surface area, and angle of attack, but I'm an architect, not an aerospace engineer.... ;-) displacement and displacement and

it does sound like the airfoil is not that important to being able to fly, and that while a flat wing might be less efficient, and have a higher stall speed, it should still work,@@TheWilliamHoganExperience

NACA>NASA

I mean, it works for the F-15

Unfortunately, too many teachers are bad at handling situations where students argue in contrast to the prescribed material.

Most teachers don't like questions that aren't in the book.

He's wrong. More than once.

@@crimony3054 About the only thing I particularly disagreed with was that the light high wing, full sized plane COULD fly, it just would need more power and possibly a bigger wing surface area. His graphic of a flat wing with a square, sharp cornered wing wasn't helpful as there's nothing to say you couldn't round off or taper down to a thin leading edge either. Sure, it wouldn't work on something like a Cesna 150 with it's stock, gutless engine but, give it more power, say about an extra 50 hp and it could. Of course stall speed would be higher too but, it would work. I'm sure as hell not intending to waste a fortune to test it but, the fact it does work fine on small scale DOES prove it can work on a larger scale too, it's just not 'the best way' to design a wing.

I think the moral of this story is that a flat wing will fly within a limit range of angle of attack. A curved wing will greatly extend the useful range of angle of attack, making the wing more versatile and practical.

@@giusdbg - I am sorry, I do not understand your comment.

The reason is the pylon introduces additional viscosity forces in the Boundary layer, which pulls the separation point upstream. Not important on the underside of a wing, because the whole point of a sharp trailing edge of the wing or flap is to force the flow to separate early.

Glad you enjoyed it!

That's also why ice on the upper surface can be a massive problem but on the lower surface nobody really cares.

Ah, the wonderful Cub! Yes, many small airplanes do indeed have a flat stabilizers. The purpose of the horizontal stabilizer is to produce a downward force. This is achieved by mounting the stabilizer with a negative angle of incidence, which means the stabilizer meets the airflow with a certain angle of attack. Moving the elevator up and down changes the curvature of the stabilizer, and hence the lift. While many old aircraft do have a completely flat stabilizer, most light airplanes do have a stabilizer with a thicker, symmetrical profile as it is aerodynamically more efficient and provides more strength. Hence, no need for struts.

Thank you for your feedback! Buy making those videos and receiving constructive comments, I have learned a lot more.

It’s ok then if you don’t have any significant objections ! Who put you in charge ?

@@tonywright8294 ... What?

lol he's a savage

There's is no percentage of Newton force vs Bernoulli force. Bernoulli's equation can, by mathematics, be derived from Newton's second law of motion, and vice versa. In other words, they are describing the same phenomenon: The relation between air pressure and velocity in an airstream. Lift is easier to understand when we apply Newton's third law. Scientinsts only use Bernoulli's equation to calculate the ratio between air pressure and velocity.

I'm sorry, Brian, but I don't know.

Thank you for your feedback!

Exactly. I have noted that every video I have seen on this subject ignores the fact that there is one constraint that always applies first.....it is that the wing HAS to have a finite thickness. This is implied but not stated in the final part where the 'flat wing' is shown not as a flat thin plate but as a rectangular box. I would expect that a thin plate would be more efficient for lift than box section shown, although lacking structural strength. Starting with a box section and then knocking off the corners and streamlining to reduce drag soon leads to a rough wing section. Aside from that I think this is a great video. Thanks Magnar!

You can get lift from a brick if you get it moving fast enough. Notice he says the flat wing fails because it "stalls". Okay, if it's stalling put some more power behind it and increase the velocity. That's why his belief that a scaled-up wing won't generate lift is faulty. A flat wing won't generate lift because you can't get it going fast enough to generate lift, not because it won't fly. Impractical for sure, but it will fly, and his reasoning is badly flawed.

The delta wing is very good for supersonic flight, as the Concorde proved. Regarding the Vulcan, a delta wing was selected for the following reasons: 1) Less drag at transonic speeds (the Vulcan had a top speed of Mach 0.96). 2) Lot of space for fuel. 3) Space to embed the engines and the landing gear into the wing. 4) A very strong construction.

bird poo can be lighter than air but only if you reduce the volume of the air by compression

You are absolutely correct. I included the F-104 in the video because it has an almost flat/symmetrical wing. It is optimized for supersonic speeds and doesn't work at medium and high angles of attack. At low and medium subsonic speeds, the leading edge flaps and trailing edge flaps must be deployed to provide enough lift.

While thin flat wings may not be as aerodynamically efficient as more specialized airfoils, the (macroscopic summarised) Bernoulli effect and the more fundamental (microscopic detailed) Newtonian laws both apply and explain lift generation. The angle of attack is the key factor for generating lift with thin flat wings. Newton's equations of motion are generally valid (outside of quantum scales and relativistic speeds).

How do observations of the lift created from flat objects create misconceptions about how lift is created? In particular if there is a conception that a shape needs to be curved to create lift.

Relative wind.

No, airfoils always create drag when lift is created

@@biingyin5522 He didn't claim that drag was eliminated.

Airfoil shape does matter though, in the sense that a more cambered airfoil creates more lift than one with lower camber at the same angle of attack. Look up Cl-alpha curves for the NACA 4412 compared to the 2412.

@@andreamusso1469 If you are aiming for maximum lift and low speed handling, power and meneuverablitly is more important than wind channel results. On my Savage Cup, the max. Lift was great before it was not. It had a very unpleasualble stall and got from tame to nasty way too fast...

@@user-yc7sg7xj4f What I mean is that angle of attack is not the whole story when it comes to lift. In fact, the traditional way of determining airfoil characteristics is by analyzing angle of attack, camber, and thickness separately. So it's not just your alpha that determines lift, otherwise there would be no difference between different airfoils.

I think he is referring to the pressure gradient force that must exist perpendicular to a streamline when that streamline is curved. From streamline curvature you can infer lower pressure inside the curve, higher pressure outside the curve.

Hahah, 1 thumb up for you!

The curvature of the wing, together with the angle of attack, is essential for lift. Aerobatic aircraft have pretty thick, asymmetrical wings. Some supersonic airplanes like the F-104 have almost flat wings, but they have flaps to allow for slow flight for take off and landing.

@@FlywithMagnar Well I'm sure you know better than I but I understand that some aerobatic aircraft have thin, flat wings. In any case, the fact that some planes can fly happily upside down says to me that the angle of attack is the primary factor in lift, and that wing curvature is secondary, perhaps contributing to efficiency.

And yes, I am sure take off and landing are not handled well upside down.

Thanks!

In fact, there was a Kickstarter project at some point that added a tiny motor and LiPo battery to any paper plane you made, and would let them fly until the battery ran out - under remote control no less...

Airliners usually cruise with the nose a couple of degrees up. The reason is twofold. One: The higher they go, the more fuel they save. Two: At high altitudes, the air is thin, resulting in a relatively low indicated airspeed. To compensate for this, they fly with the nose a few degrees up, as this increases the angle of attack, and with it, the lift coefficient. Wings are designed to be most efficient at a higer angle of attack (7-8 degrees for a straight wing), but this will result in a relatively low cruise speed. Therefore, some efficiency is sacrified for a higher cruise speed. The airflow under the wings contributes to some of the lift, but the airflow over the wings is more important. Here is a link to a video about the lift formula: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-e43l2V_MFIY.html

@@FlywithMagnar Thanks a lot for your explanation 👍

@@FlywithMagnar ... Yes, but if the airliners do most of their cruise flying with an attitude of 1 or 2 degrees nose up, they could have designed the wing to be mounted on the fuselage with an incidence of 1 or 2 degrees more. As an aeronautical engineer, I have always have this doubt myself. I found several explanations, and I don't know which of them if any are true. 1- The airplane is designed to fly with an attitude of no less than 0 degrees because flying a bit nose down is more uncomfortable for the pax than flying a bit nose up, so the whole range of cruise attitudes (different weight, altitudes, speeds and CG) are designed to have 0 degrees as the lower bound. 2- It is to reduce drag by better streamlining the aft fuselage with the airflow, which will not be horizontal but tilted downward due to downwash. Also the tail cone is tilted up so having the aft fuselage tilted down again aligns the tail cone with the airstream better. 3- To create a little bit of body lift, hence reducing a little bit of wing lift and reducing induced drag. I know this one HAS to be false. While the fuselage may create a little bit of lift by flying at an angle, it is super inefficient generating lift when compared with the wing, and it will create more drag for unit of lift. Any lift that you can take out of the fuselage and put it on the wing will result in a lower drag. 4- To provide a more nose-up attitude during landing and avoid a nosewheel-first touch down. If the plane flew with the fuselage 2 degrees less nose up at cruise, it would also touch down with the fuselage 2 degrees less nose up, and since it does touch down with about 2 or 3 degrees nose up to begin with, that would put the nosewheel dangerously close to touching down first. Not sure about this one. Tail strike seems to be a more common problem than a nose wheel landing. Also the problem could be solved by shortening the nose strut a bit.

@@adb012 Point 4.... They rarely come down with the same nose up attitude. In fact they point downwards, mostly, to lose altitude - which is my experience as a passenger.

@@RaviKumar-sn2lx ... I don't get your point. Airplanes touch down with the main landing gear first (the wheels under the wing) and they have a nose-up attitude at that point. Then, once the main gear is on the ground, they lower the nose and the nose gear touches down. If the wing was installed with, say, 2 degrees more of incidence, then, at any given speed and weight, the fuselage would fly so degrees more nose down or less nose up (because the wing, which is the thing that makes the lift, will have the same angle relative to the incoming airflow, so instead of the wing being installed on the fuselage with 2 degrees more of incidence, you can think about the fuselage being installed on the wing with 2 degrees more nose-down angle), and that would make the nose gear touch down first (or very close to that) unless you change somethin else like making the main landing gear longer or making the nose gear shorter.

You are talking about two different mediums: Water and air. While they have some common properties with it comes to fluid dynamics, they have very different density and viscosity. The stone is moving through the air because it has a high kinetic energy. And it skips the water because of the smooth surface of the stone and the relatively high density of the water. As the energy dissipates, the stone will eventually sink into the water. Therefore, you cannot compare skipping stones with wing lift. Regarding your quesiton: No, the boundary layer is often disregarded when lift is explained. It is the difference in static air pressure between the upper and lower surface of the wing that creates lift.

Fool in the video says it won't scale up, but that defies the wind tunnel experiments performed by the Wright Bros., who tested small wings in wind tunnels and scaled them up. Likewise, the Wrights scaled up the aerodynamics they refined with their kites and gliders. Doesn't scale -- now that's a laugh. 🤣🤣🤣🤣🤣🤣

@@crimony3054 Yep, his assertion that it "doesn't scale" lacked evidence.

​@@crimony3054 I think he meant 'doesn't scale' more in the sense that you need to compensate for the bad airfoil shape with much more engine power, the catch is doubling the size os a wing makes its area 4x times larger, but it'll end up weighing 8x as much. TL:DR I think he meant the square-cube law.

In the video, I discussed a flat wing with a sqared off leading edge. If the flat wing has a rounded leading edege, it will be able to produce more lift. In the video, I show the F-104. Without the maneuvering flaps, it will not not be able to fly, unless it is moving very fast. A flat wing with maneuvering flaps is a modern copy of the wings used in the first airplanes, wich in turn is a copy of a bird's wing. The nature has been, and still is, an insporation for the engineers.

@@FlywithMagnar It seems obvious that to have that squared off L.E. and T.E. is counter productive. The basic comparison with a flat wing is to one with little thickness, so the blunt L.E. doesn't cause such a problem. The Japan data is of a very thin wing similar to the common small. balsa model without the thick blunt edges causing more turbulence. . To land, the F-104 required engine air blown over the wing which was called Boundary Layer Control - BLC . However. . . The Wrights also observed that the L.E. shape had a profound effect and If I recall correctly, a squared off L.E. appeared to perform best in their tests, but I think it was hardly more than an inch or two thick.

To my knowledge, the Wright brothers never tested a wing with a squared off leading edge. They ended up with a thin, cambered airfoil with a rounded leading edge. Here is a good description of the evolution of the wing profile: greydanus.github.io/2020/10/13/stepping-stones/ Regarding the F-104, bleed air was not blown over the wing. It was directed over the flaps from a duct inside the wing. It is indicated with an orange circle in my video at 10:48.

@@FlywithMagnar RE: Wrights. I did not mean to imply the Wrights used a thick flat wing similar to what you show. They had some type of wooden, leading edge that we can call a spar. I don't recall reading its thickness, but its shape was definitely discussed in one of the many books written. I don't recall which, but I read all I could get my hands on, perhaps 20 years ago, about them and some others at that time. If I had to guess, I would first say the one 'official' book Orville wrote with Fred Kelly. I distinctly recall it mentioned. It was one example of the level of detail they went to.. It may have been in reference to the wind tunnel tests, or in a glider, or in a letter to Chanute, but they did look at LE shapes. I recall thinking about how much it could affect such a thin vertical dimension. Unfortunately, I don't recall exactly what was said - what shape was better or worse, but seem to recall that they saw some advantage to a squarer LE shape. I can't recall if I looked closely at the one at the Smithsonian when I visited, quite some time ago . Yes, I mis-spoke saying it was over the 'wing'. I built a plastic F-104 model back in the early 60s which is when I learned about it's BLC. I don't think I read s full description, or if I did, I've forgotten details. You imply it can't *fly* without flaps, but it is low speed flight that is the problem with the thin, small area wing. It couldn't *land* engine-out as there was a minimum RPM for the compressor to provide its effect. (of course it couldn't take off) .. The idea is also slightly similar to the 1943 Custer Channel Wing concept. That *was* an entire above wing augmented flow from the prop engine. that was further investigated in the early 2000s by a NASA funded project at Georgia Institute of Technology Research Institute. It had the problem in that at the low speed afforded by the augmented flow, It landed very nose up and the low speed flow over the control surfaces made low speed flight troblesome. I spoke with the Georgia Tech leader Bob Englar several years ago. A drawing he showed me had a forward-mounted, above wing jet engine of some type that did a true Coanda flow traversing the full chord, including flaps. Thanks. I see we've drifted far off topic. I simply wanted to point out that a thin, flat wing has a fascinating flow as shown in Anderson. Regards.

@@Observ45er A CL “of about half” will require 41% more airspeed to achieve the same lift. Not “25%”. But that is beside the point anyway. You could accelerate up to, say, 1.05 Vs, rotate, and yet be unable to sustain flight, or even maintain speed. You have to know the Vy, the drag, and the power available before you can answer this question. The TO and climb performance would certainly be in the range awful to nil. Hypothetically, you could just about make something like a C-172 fly with a flat wing (of the same area) and the rated power of an O-320, and an optimised prop. It seems plausible that a structurally adequate flat wing could be constructed at typical GA aspect ratio with a 6% thickness. However, it is a highly marginal case for such a thing to get airborne at representative operating weight of, say, 1 tonne. Nobody has tested such a ridiculous airfoil at the kind of Reynolds numbers we are talking about (3 million range) so the data is simply not available to nail down exactly how bad the performance would be. Nonetheless, the point I am making is that it has nothing to do with CLmax. If it cannot fly at its Vy, it cannot fly period.

This is called a knife edge. The lift is created by the fuselage, which is pointed a bit up. The pilot must apply a lot of rudder to keep the nose up. A belly tank is a benefit as it will increase the lift.

Fighters often use ballistic manoeuvres as opposed to aerodynamic ones... At 500 mpg, you can do funny things just using inertia and ballistics... Like sitting in a bullet with control surfaces

NACA 0012 has 0 camber and a thickness of 12%. The surface is not flat. airfoiltools.com/airfoil/details?airfoil=n0012-il While this profile is used on Jet Ranger, S-51 and other helicopters of "old" design, the majority of new helicopters have rotors with cambered airfoil because they are more effective.

@@FlywithMagnar 0 camber defines a flat profile chord... The NACA 0012 is a flat plate with an aerodynamic shape :-) Even R22, R44 and R66 use this one and it works fine

@@user-yc7sg7xj4f, you might be confused by the definition of camber. NASA: "A cut through the wing perpendicular to the leading and trailing edges will show the cross-section of the wing. This side view is called an airfoil, and it has some geometry definitions of its own. The straight line drawn from the leading to trailing edges of the airfoil is called the chord line. The chord line cuts the airfoil into an upper surface and a lower surface. If we plot the points that lie halfway between the upper and lower surfaces, we obtain a curve called the mean camber line. For a symmetric airfoil (upper surface the same shape as the lower surface) the mean camber line will fall on top of the chord line. But in most cases, these are two separate lines. The maximum distance between the two lines is called the camber."

Sorry but no. As the video rightly stated, it is neither the low pressure nor the high pressure that results in lift, it is the difference between the two. It is just a matter of semantics to argue about whether the wing is being sucked up or pushed up, the ‘net external force’ is the same either way. Nonetheless if you look at the pressure plot for a typical airfoil at moderate angle of attack you will find more ‘low’ pressure on the upper surface than ‘high’ pressure on the lower surface (shown in the video). Hence if you want to talk in terms of pushing and sucking - and you do - it is more sucking. And there is actually an engineering reason to be aware of that, but I will let you try and figure it out. As for the argument of whether to label an arrow “lift” or “push”, just label it how you want mate. But know that the word the industry has alighted upon since about 120 year ago is lift, so good luck convincing all the people who actually work with this stuff to switch over to the jargon of dhy5342 of youtube.

@@XPLAlN Regardless of 120 years of convention and labels, the scientific, physical forces of nature only recognize pressure as a force; "suck" does not exist. Only pressure can exert a force on an object such as an aircraft wing. Show me, if you can, any single instance where 'Sucking" or low pressure effects a reaction.

@@dhy5342 Lol. I know there are a few people who object to the word suck. I don’t care, it is a purely semantic argument because we define it to be what we want. It is arbitrary. As I said, use whichever word you wish to. But you believe “lift” should be replaced with “push”. You actually wrote it. And I am telling you that is not going to happen because all the people who need to actually work with this terminology are happy with what we have. So off you go with your words back under your little bridge, or span if you prefer to call it that, I don’t care which.

@@XPLAlN “Who is so deafe, or so blynde, as is hee, that wilfully will nother heare nor see.” ---John Heywood, 1546 "Whenever one object exerts a force on another object, the second object exerts an equal and opposite on the first." ---Isaac Newton, 1686 (Principia Mathematica Philosophiae Naturalis) 'Hear now this, O foolish people, and without understanding; which have eyes, and see not; which have ears, and hear not'" ---Christian Bible, Jeremiah 5:21 "Absent a rope or some other pulling method, there is no lift from above, only a push from below" ---dhy5342, 2023

@@dhy5342 Pure semantics. No substance.

It is the relative velocity between the wing and the air that counts. Whether the wing is stationary in a wind tunnel or moving through the atmosphere is of less importance. A wind tunnel has some limitations, but it is a very good tool when designing aircraft.

@@FlywithMagnar I think you need to re-read the last half of my last sentence ;-) I do agree with you fully (though you do have a deeper knowledge then I do), my point was to explain why so many "ideas" exist on the topic.

It is high pressure. You may be thinking of the wake of the object and the low pressure within the wake. That is pressure drag.

You can add drag to the equation. Insect wings are neither 100% flat nor fixed. They can flap and swivel. So it would have been more accurate to use the aerodynamics that are applied to helicopters. Aircraft engineers are using turbulence to create lift. Examples are vortex generators (increases critical angle of attack) and leading edge root extensions (LERX) on fighter aircraft (creating a powerful vortex over the wing root).

If it has a streamlined edge, it's not flat.

@@clintoncoker6 Seriously, are we really going to argue about word meanings here? It is flat if it can lie flat on a flat surface, whether or not the edge is rounded. Are you also going to tell me the countertop in my kitchen is not flat? Well, it is flat, and the edge is rounded, and it would make a better wing than one that has a squared-off edge.

@@satunnainenkatselija4478 Magnar said an airplane with a flat wing will not fly, which is inaccurate. If instead he had said a flat wing with a square leading edge would not fly very well, that would have been accurate. In this context flat means a surface without curvature, and the pertinent surface is the large area of the wing, which is curved (not flat) for most airplanes. Regardless of the leading edge treatment this is a flat wing, as opposed to the usual curved wing surface. But Magnar's drawing is really just a thick flat plate, not a wing intended to actually fly well. First of all, a flat plate is actually quite efficient at producing lift in supersonic flow. There is no flow separation, and the sharp corners produce expansion waves that are the source of pressure differential and aerodynamic forces. But nobody would expect that wing to work well at useful angles of attack in subsonic flow, even though it would still fly given enough airflow. However, all you have to do is taper the leading edge to expand the useful angle of attack range to allow a flat wing to work better. It will not be very efficient at low speeds, but it will fly. More than one aircraft has had a flat or nearly flat wing and flown to quite useful angles of attack, such as the X-15.

That is not correct. The "vacuum' above the wing is not the sole source of lift. Newton's Third Law of motion is also responsible for creating lift.

I agree, although Newton's third law of motion contributes less than the vacuum-like effect, or, in other words, the Bernoulli principle. It is true that lift is a result of both pressure differences (as described by Bernoulli's principle) and the deflection of air (as described by Newton's Third Law). The precise contribution of each depends on various factors like wing shape, angle of attack, and flow conditions. In modern aerodynamics, both explanations are understood to be different facets of the same phenomenon, and neither can be ignored.

FUNNY YOU HAD F104 WITH THX

Your example with the bridge is to a certain degree similar with airplanes. In the video, I show an image of a model airplane with a wing made of square cut foam. The wing loading is very low, and the power to weight ratio is very high. Such model airplanes can fly. But if you scale up that wing and put it on a Cessna 172, it will not be able to fly. If you round off the leading edge and sharpen the trailing edge, the wing will provide more lift, but it will not be very efficient. You can scale up a model aircraft, but you cannot scale up the air molecules. Therefore, a model airplane will have different flying properties than a full size airplane.

@@FlywithMagnar 👍 have a nice weekend, Martin

The vortex created at the wing tip does not create lift. Only drag. That's why a wing with a long aspect ratio (for example a glider) is more effective than a wing with a low aspect ratio.

Fair question. If I may expand a little on Capt Nordal’s reply. The short answer is: the tip vortex itself is a circulation, not a downwash, so it does not increase lift iaw Newton’s 3rd. The tip vortex will increase average downwash over the span. However, being a vortex it is circulating so there is no net extra downwash of air. The ‘up’ part is happening outside the tip. Nonetheless, the span gets the downwash part so that reduces the ‘effective angle of attack’, hence reduces lift (relative to a hypothetical no tip vortex case aka 2d section or infinite span). Ergo, for any given required lift, this shortfall has to be recovered by increasing the angle of attack somewhat. The net result is same lift but more drag for the real wing than the hypothetical no tip vortex case. That difference is ‘induced drag’. One of many references is Aerodynamics for Naval Aviators, p66, downloadable from the FAA website.

Is there really a difference between a wing moving thru air and air moving over a wing?

Same thing - the pressure difference makes the air move inside bringing the particles with it. Sucking something into a pipe means creating an underpressure in the pipe to establish the pressure difference, it's a colloquial term.

@@altoclef6688 Yes but it's the air particles from the higher pressure that do the work, a vaccuum has no energy to perform any sucking.

@@ottonormalverbrauch3794 Yes. But in colloquial terms talking about a blower because the normal pressure air flows into the pipe bringing the particles with them, would be confusing. Physically sucking does not exist since the lower pressure side does not exert force, but in colloquial terms it is handy. Sipping from a straw or sucking on the straw is a useful term for every day, saying "create an underpressure so the atmospheric pressure pushes the fluid into your mouth" would be useless from a conversation perspective. So just accept colloquial terms and scientific terms have their separate fields of usage...