Whenever I see an explanation about how airplanes can fly, I see that the shape of the wing is different on the top side to create a dragging force that pushes the airplane up. The top is curved and the bottom is flat. If a airplane turn upside down, should it fall faster because it’s dragging down ? I saw airplanes doing acrobatics on air , and some of them looks impossible because of this.
In: Engineering
This is because the lift that a wing generates is also impacted by the [angle of attack](https://www.skybrary.aero/images/8/8d/AoA.jpg), or how the plane’s wing is angled towards the oncoming wind. In the picture that I linked, you can see that it has a positive angle of attack (the wing’s leading edge is pointed slightly upwards) and most airplane wings are optimized to generate lift in in this configuration. However, if you gave the wings a negative angle of attack (so they’re pointing downwards) they would actually generate lift downwards. This is what airplanes do when they fly upside down. Aerospace engineers can use something called a [lift curve](https://upload.wikimedia.org/wikipedia/commons/2/22/Lift_drag_graph.JPG) to examine the relationship between the angle of attack and the lift that a wing generates. In this image, you can see that a negative lift can be generated at a negative AoA.
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