The science behind how airplanes fly in the sky With Water 10 July 2022

10 july 2022 We all want to know that how the Airplanes now fly waith normal water in the sky so here we need to learn some basic things lets start from Memphis International Airport is one of the busiest airports in the world and as the jets fly off, have you ever wondered how they lift off the ground?
In this episode of The Breakdown, we go in detail on how airplanes actually fly and what forces them to lift off the ground.
Airplanes fly because they can generate a force called lift which normally moves the airplane upward. Lift is generated by the forward motion of the airplane through the air. This motion is produced by the thrust of the engines.
Drag is the force produced by the resistance of the air to the forward motion of the airplane. An example of this is by swishing your hand rapidly side-to-side and you will feel that resistance on your hand.
Weight is also an important part of the plane, this is the force created by the pull of gravity toward the center of the Earth. You will feel the effect of this force if you jump up on the floor. Your weight will force you back down.
When then thrust produced by the engines is greater than the force of drag, this happens as the airplane moves forward. When the forward motion is enough to produce a force of lift that is greater than the weight, the airplane moves upward.
While any part of the airplane can produce lift, the most lift comes from the wings of the plane. 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.
In a lot of science books and web pages, you'll read an incorrect explanation of how an airfoil like this generates lift. It goes like this: When air rushes over the curved upper wing surface, it has to travel further than the air that passes underneath, so it has to go faster (to cover more distance in the same time). According to a principle of aerodynamics called Bernoulli's law, fast-moving air is at lower pressure than slow-moving air, so the pressure above the wing is lower than the pressure below, and this creates the lift that powers the plane upward.
Although this explanation of how wings work is widely repeated, it's wrong: it gives the right answer, but for completely the wrong reasons! Think about it for a moment and you'll see that if it were true, acrobatic planes couldn't fly upside down. Flipping a plane over would produce "downlift" and send it crashing to the ground. Not only that, but it's perfectly possible to design planes with airfoils that are symmetrical (looking straight down the wing) and they still produce lift. For example, paper airplanes (and ones made from thin balsa wood) generate lift even though they have flat wings.

But the standard explanation of lift is problematic for another important reason as well: the air shooting over the wing doesn't have to stay in step with the air going underneath it, and nothing says it has to travel a bigger distance in the same time. Imagine two air molecules arriving at the front of the wing and separating, so one shoots up over the top and the other whistles straight under the bottom. There's no reason why those two molecules have to arrive at exactly the same time at the back end of the wing: they could meet up with other air molecules instead. This flaw in the standard explanation of an airfoil goes by the technical name of the "equal transit theory." That's just a fancy name for the (incorrect) idea that the air stream splits apart at the front of the airfoil and meets up neatly again at the back.

So what's the real explanation? 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 (much more dramatically—because that's what it's designed to do). 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 (not the other way around, as in the traditional theory of a wing). The difference in speed (observed in actual wind tunnel experiments) 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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