This is a brilliant piece of work that is not enough appreciated. 1. At 0:17 the position field of the air particles is shown, with the vertical being the position of the particle and the horizontal being the time instant. Now within this field shown there exist the velocity vector field, and the acceleration vector field which can be deduced by differentiating the image in question twice. The accelerations of the air particles are what decides the pressure distribution at any point. 2. The scene at 0:17 has basically horizontal lines and differentiating the elements of nearby distances covered in an element of time would show that basically, the particles have the same horizontal velocity. 3. The fact that 0:17 basically consists of horizontal lines indicating the moving particles from right to left, then means that there is no acceleration at any point in the two-dimensional field shown. No acceleration of the mass particles means that there is equal pressure all around the area shown. 4. At 0:23 the fact that the leading edge is bent down a little, it is clear that this is sucking the particles of air creating a partial vacuum under the leading edge. Most airfoil sections miss this fact, but it is important to keep it in mind as it forms part of the principle of how an airfoil operates. At 0:30 this low-pressure effect under the leading edge is still seen. At0:37 the bending down of the leading edge is eliminated and so the fluid is not being accelerated anywhere in the field of view. 5. At 1:20 I CONSIDER THIS ACTION AS BEING THE GENERAL EXPLANATION OF HOW ALL AIRFOILS OPERATE AS IT SHOWS THE FOUR ( 4) PRINCIPAL ZONES ONE NEED TO CONSIDER IN EVERY AIRFOIL EACH DESIGNED FOR A PURPOSE IN MIND WHICH NEEDS THE MODIFICATION OF EACH OF THE FOUR(4) DIFFERENT ZONES. 6. The zones of consideration are the following. All shown at 1:20 6a The suction zone under the leading edge. 6b. The higher pressure compression zone over the leading edge. 6c. The pressure compression zone under the lower surface behind zone 6a going as far as the trailing edge. 6d. The suction zone over the upper surface behind zone 6b going as far as the trailing edge. 7. Though it is not so obvious to recognize all the four zones still exist with the airfoil shown at 2:31 they have been modified to suit a better performance at a higher speed. Note that in this wind tunnel it is the air particles that move with the airfoil remaining horizontal. In real flying, it is the airfoil that moves and the air is initially stationary and basically, that air moves vertically up and down when the airfoil section passes through. In fact to get a better picture the real action in an airfoil section is more of a stationary golf ball being hit by a specially shaped golf club with the golf ball rising and dropping in a vertical position with little horizontal motion. 8. It is interesting at 2:57 how under the leading edge the air particles always climb up to fill the space under the leading edge for different angles of attack. Obviously, this rising of air particles to fill under the leading edge is not only due to the sucking effect ( 6a) under the leading edge but with the angle of attack, the high-pressure zone under the trailing edge will help also . 9. It is interesting that in any petrol and diesel and jet engines, one needs to compress the air before it gives a back more useful performance, The compression zone over the leading edge and the suction zone under the leading edge may first appear to be detrimental but THE ENGINEERING DYNAMIC LOGIC THAT EXISTS IN THE FOUR PRINCIPAL ZONES IN AN AIRFOIL WILL BEND THE AIR MORE EFFICIENTLY TO PRODUCE A BETTER LIFT. 10. From the location of the particles field shown at 3:47 it would be useful to differentiate it twice to obtain the acceleration vector field as that would represent the pressure field all around the airfoil section. 11. The two fast vortexes that appear at 4:56 behind the leading edge at that angle of attack do not exist at the same time, but one forms and then it generates the other where the first will die out and the second one grows till it generates the first one to die. and the action is repeated to eventually oscillate the turbulent air behind the trailing edge. Congratulations to the compiler of this video.
Thanks for the explanation. I was wondering about the suction at the bottom of the leading edge and also the point of showing the flat plate at the beginning. Now it makes so much more sense to me.
Thank you. old but very usefull. I would like to see on symetric wing but rotate 180º. like arrow instead like wing. 2:18 having air flow coming from the back to see lift and drag.(maybe dont build lift if the front is narow than the tail.)
The authors have two wrong scientific approaches: researching the creation of Lift force and Low pressure at upper side of the wing, relative to the ground surface and Earth. I explain the aerodynamic cavitation and existence of Lee side aerocavern, and creation of Aerodynamic force. Low pressure creates force normal to the cord (contact surface), and it name is "aerodynamic force" because is made from the air (aero) in motion (dynamic), or wind relative to the wing (object).
Recently the 100yr old Mystery of Airfoil Lift has been solved finally ! Check Tekemon. The reason it took so long to get to the reality of lift was the basic error in assuming there’s some kind of flow of air over the airfoil, which gave rise to various erroneous non-existent and irrelevant concepts e.g. Bernoulli, Flow-Separation,etc. Everything is covered in the book, in detail. The matter was a very simple one, but the wind tunnel gave the scientists true tunnel vision for the past century. Check tekemon to really know how Lift is generated by an airfoil.
