​​How Do Wings Make Lift?

In one sentence, wings make lift by changing the direction and pressure of the air that crashes into them as the engines shoot them through the sky. Okay, so the wings are the key to making something fly, but how do they work? Most airplane wings have a curved upper surface and a flatter lower surface, making a cross-sectional shape called an Airfoil.

As a curved airfoil wing flies through the sky, it deflects air and alters the air pressure above and below it. That’s intuitively obvious. Think how it feels when you slowly walk through a swimming pool and feel the force of the water pushing against your body: your body is diverting the flow of water as it pushes through it, and an airfoil wing does the same thing. As a plane flies forward, the curved upper part of the wing lowers the air pressure directly above it, so it moves upward.
Why does this happen? As air flows over the curved upper surface, its natural inclination is to move in a straight line, but the curve of the wing pulls it around and back down.

For this reason, the air is effectively stretched out into a bigger volume the same number of air molecules forced to occupy more space and this is what lowers its pressure. For exactly the opposite reason, the pressure of the air under the wing increases: the advancing wing squashes the air molecules in front of it into a smaller space. The difference in air pressure between the upper and lower surfaces causes a big difference in air speed. The difference in speed is much bigger than you’d predict from the simple (equal transit) theory. So if our two air molecules separate at the front, the one going over the top arrives at the tail end of the wing much faster than the one going under the bottom. No matter when they arrive, both of those molecules will be speeding downward and this helps to produce lift in a second important way.

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