Why do wings generate lift

Space is nearly a vacuum. Without air, there is no lift generated by the wings. Lift is generated by the difference in velocity between the solid object and the fluid. There must be motion between the object and the fluid: no motion, no lift.

It makes no difference whether the object moves through a static fluid, or the fluid moves past a static solid object. Lift acts perpendicular to the motion. Drag acts in the direction opposed to the motion.

You can learn more about the factors that affect lift at this web site. Postgraduate courses How to apply Fees and funding Frequently asked questions. International students Continuing education Executive and professional education Courses in education.

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Research at Cambridge. Home Research News How wings really work. What types of animal do we use? S2 ep2: What did the future look like in the past? S2 ep 3: What is the future of wellbeing? S2 ep4: What would a more just future look like? There are reasons that it is difficult to produce a clear, simple and satisfactory account of aerodynamic lift.

Some of the disputes regarding lift involve not the facts themselves but rather how those facts are to be interpreted, which may involve issues that are impossible to decide by experiment. Nevertheless, there are at this point only a few outstanding matters that require explanation. Lift, as you will recall, is the result of the pressure differences between the top and bottom parts of an airfoil. We already have an acceptable explanation for what happens at the bottom part of an airfoil: the oncoming air pushes on the wing both vertically producing lift and horizontally producing drag.

The upward push exists in the form of higher pressure below the wing, and this higher pressure is a result of simple Newtonian action and reaction. Things are quite different at the top of the wing, however. A region of lower pressure exists there that is also part of the aerodynamic lifting force. We know from streamlines that the air above the wing adheres closely to the downward curvature of the airfoil. This is the physical mechanism which forces the parcels to move along the airfoil shape.

A slight partial vacuum remains to maintain the parcels in a curved path. This drawing away or pulling down of those air parcels from their neighboring parcels above is what creates the area of lower pressure atop the wing. But another effect also accompanies this action: the higher airflow speed atop the wing.

But as always, when it comes to explaining lift on a nontechnical level, another expert will have another answer. But he is correct in everything else. The problem is that there is no quick and easy explanation. Drela himself concedes that his explanation is unsatisfactory in some ways. So where does that leave us? In effect, right where we started: with John D.

This article was originally published with the title "The Enigma of Aerodynamic Lift" in Scientific American , 2, February How Do Wings Work? Holger Babinsky in Physics Education , Vol. David Bloor. University of Chicago Press, Understanding Aerodynamics: Arguing from the Real Physics.

Doug McLean. Wiley, You Will Never Understand Lift. Their angle of attack is increased to ensure their lift continues to support their weight as they slow down. Wings and tails need to be movable so that their shapes can be changed to control their flight.

To understand this principle, we need to understand air pressure. Air is composed of several invisible gases that have mass. This mass is made up of molecules, moving in rapid random motion, and exerts a force called air pressure. We are unaware of this pressure because it is evenly pressing all around us.

If the air pressure is not even, the greater pressure pushes an object in the direction of the weaker or lower pressure. In , Bernoulli found that, when a gas like air moves, it exerts less pressure. Normally, air moves along smoothly in streams, but airflow is disturbed when a wing moves through it, and the air divides and flows around the wing. The top surface of the wing is curved aerofoil shape.

The air moving across the top of the wing goes faster than the air travelling under the bottom. In other words, air below the wing pushes on the wing more than air above the wing. This difference in pressure combines with the lift from the angle of attack to give even more lift. It used to be claimed that the air travelling over the top of the wing took the same time to reach the back of the wing as the air travelling along the bottom.

This has been shown to be incorrect, but it has been shown that the speed of the air over the top is faster than the speed of the air under the bottom. The shape of the aerofoil is different for different aircraft.