Airfoil Basics

[ChrisZoomER]

Trivia: Thicker airfoils are used for low speed flights while high speed flights require thinner airfoils to minimize drag.

[myusername]

A lot of modern fighter aircraft have fuselages shaped like airfoils to generate lift to aid with wings in maneuverability and also improve slow speed flight as the fuselages are basically very thick airfoils.

[carmelpule]

Air and hydrofoils work as follows. If one needs to produce force, one has to accelerate or decelerate MASS. If the mass happens to be a branch tied down to a tree or fixed on the ground, then the mass will not move but the acceleration force will be transmitted to the activity that is trying to accelerate the mass by pushing or pulling/suction action. If the MASS happens to be a lump of fluid like water or air which can distort and change its shape, then, to create a force one still needs to accelerate a lumped mass of soft air or water. This is a case of having to use either the INERTIA OF REST OF THE HEAVY lump of FLUID OR THE INERTIA OF MOTION OF THE FLUID IN QUESTION. One particular lump of fluid when accelerated will distort and change position, and so an accelerated lump of fluid can only serve to create a force if the acceleration is done for a short temporary period when that lump mass occupies an inconvenient location and then is dumped and one needs to grab at another nearby lump mass and try and accelerate that till again, it distorts and changes position, when it has to be dumped, and the process repeated on other nearby lumps of fluid masses. Now let us apply this to an airfoil section. We shall use an old-fashioned slow one as shown on the bottom right-hand corner shown at 0:15. as it shows zones of activity that are not shown on the other airfoil sections. THIS IS THE REALITY OF AIRFOIL SHAPES shown in an old-fashioned airfoil section of more than 100 years ago.

To make it easier to understand, let us be realistic, yet practical, and rather than use wind tunnels where the airfoil is stationary and the air flows with a horizontal velocity, we take a real airfoil that is moving and the fluid/air that is still. To make it even easier, let us assume that when the airfoil pushes or sucks the still air mass lumps/ particles, it will accelerate them VERTICALLY only and we can forget about any horizontal velocity of the mass lump particles of the fluid. After all, a heavy stationary golf ball can be hit by an angled golf club to rise vertically up or down, and water can be sucked up by a straw to also go vertically up or down. All this is what happens in an airfoil section, elevators, rudders and ailerons, and propellers!!!

Considering the airfoil shown on the bottom right-hand corner shown at 0:15 moving with a horizontal velocity. Consider two stationary mass lumps of particles, one mass lump being pushed up, accelerated vertically by the upper inclined angle of the leading edge, and the other mass lump, being pulled up, accelerated vertically by the suction of the void behind the underside leading edge. These two actions will put pressure on the upper leading edge, and suction on the lower leading edge, all for a good investment to pay off handsomely later on.

After the accelerated top mass fluid lump( surrounded by other lumps) tries to leave the upper leading edge surface, moving vertically up, it acts like a moving piston leaving a suction effect behind it and so this suction effect will slow down the vertical up velocity of the fluidic mass lump at the expense of lifting the upper surface of the wing moving horizontally below it. The downhill slanting shape on the rear part of the upper surface of the moving wing will accelerate the mass lump downwards through a suction effect and the mass lump with its now vertically downward velocity will be dumped over the trailing edge. This is the lift action on the upper surface of a wing.

The lower fluid lump mass initial upward sucking acceleration by the under- curve, shape of the leading edge is slowed down and decelerated by the moving undersurface angle of attack pushing on it and so the upward going lower mass lump will start to slow down and even change directions downwards because the sloping rear part of the underwing, all applying the law that to every action there is an equal and opposite reaction, be the initial forces exist due to suction or compression accelerations. The lower mass lump moving vertically downwards is also eventually dumped after the leading edge, not necessarily at the same time as the upper one was dumped. In fact, they are dumped at two different times causing a trailing edge vortex along the trailing edge. Bernoulli may be shelved for the time being and given a holiday and not asked to take part in explaining how a wing works due to change of pressures and is all the short-lived and temporary accelerations and decelerations of lumps of fluid masses at different zones around the wing/ rudder, elevator, aileron, four propellers, pumps, diffusers, etc including afterburners..

Note, the above pushing and suction actions and their sequential force reactions, above and below the wing surfaces, can take place because the fluid is homogenous and the two mass fluid lumps are sealed in like moving pistons in cylinders, by other nearby mass particles around them. All this assumes that there is no boiling of fluid at the heaviest suction zones which may cause cavitation in water and boiling of moisture in the air around the wings and propellers.

So Basically the wing has four major fundamental locations that operate on mass lumps of homogeneous fluid in question, basically in a vertical up and down acceleration with their resulting reacting forces. The little horizontal motion of the lumps of fluid around an airfoil or a hydrofoil may be neglected for better lift understanding. The horizontal accelerations of the lumps of fluid will contribute to the drag and not the lift of the wing. The four principal locations of a wing /propeller etc are as follows.

1. The upper leading edge, accelerates the stationary mass lumps to move vertically upward due to a compression zone action and after this,
2. The horizontally moving sloping rear part of the upper surface sucks back the vertically moving mass fluid lumps to eventually change their direction downwards to dump them over the upper trailing edge. This is the lift in the upper surface of a wing.
3. The lower leading edge, accelerates the stationary mass lumps vertically upward due to a suction action and after this
4. The moving sloping rear part of the lower wing surface is pushed, compresses back the vertically up moving lump mass to change their direction to a downward velocity, and eventually dump it at the upper trailing edge.


All airfoil sections, from slow high lift ones to medium, high-speed supersonic ones, all do is to re-design these four major locations of an AIrfoil section to ACCOUNT FOR THE INERTIA OF REST/MOTION OF THE FLUID BEING USED relative to the speed of the wing, foil in question.

For high-speed airfoils sections, and in water propellers/ hydrofoils, the upper leading-edge compression zone is kept at a narrow-angle and surface rate of changes, to reduce/limit the acceleration of the fluid which would vapourize all the moisture in the air and boil water in water foils, to cavitate the fluid. For medium, to high-speed airfoil sections, the suction underside leading edge is done away with and the lumps of heavy fluid are accelerated down vertically by the cushioning fluid and the angle of attack of the undersurface of the wing.

All that was explained above, any shape eye can see it all in the flying of the owl shown in this video, and it adds more showing how the fluid mass lumps of air can escape at the leading edge, the trailing edge, and the wingtips at high angles of attack.


Rather than considering the velocity streamlines around the wing, it is better to see the linear rate of changes and the circular rate of changes that will produce a vector acceleration field around the airfoil section AND IT IS THE INTEGRAL OF THE ACCELERATION FIELD IN THE VICINITY OF THE WING THAT WILL GIVE THE TOTAL LIFT VECTOR AND TOTAL DRAG VECTOR N THE REQUIRED DIRECTIONS.

[richarrrdj]

The Wright Bros flew on around 16 horsepower with very low octane fuel. They built their own aluminum in line engine including the carburetor. They tested out their airfoil before use on wings and propellers. They got 80 lbs of thrust from their big propellers.

[Kenny-Ross]

Quick and straight to the point. Thank you!

[ordnanceant]

Get tp the good point about the camber then stops....would be good if you uploaded the rest of this video

[hopolo]

more accurately, airfoil shape depends on the density of the fluid, not the altitude per se. 0:08

[jeanfranco]

I was planning to design an airfoil for an acrobatic aircraft for its wing, but I'm still not sure if I should go for a high-cambered wing for the lift coefficient or symmetrical for maneuverability.

[soon]

Who the F disliked this vid!!! This vid is amazing!!!

[Lofi-Champ]

Can you please make a video on Airfoil Terminology

[chcornell]

Angle of incidence, this we cannot change.
Helicopter pilots: oh, really...?

[eastindiaV]

Airfoil basics:

Asymmetrical airfoils are the only design for airplane wings, and horizontal control surfaces.

Symmetrical are for aerleons, elevators, and rudders

Or, for rockets, and missiles.

Goettingen 1919, is the best Airfoil, because it is my hand drawn design, and stands the test of time

Which is why I hand draw them, every time

[Manashorts-s]

I want Aerofoil shape blade design for gas turbine sir. Please reply sir please🙏

[cabilgibbs]

Keep working at it. You are very smart. Youll find groove. Just keep Going.

[rafmontalban]

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[tiagobraga]

No that's for sure 100% definitely Peter.

[ABWEndon]

Camber is pronounced "cam" as in camera