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Does the Magnus effect apply to airplanes?

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Aerodynamics

PHAK 3-3 lists Bernoulli, Newton, and Magnus as the prime culprits in the production of lift. I understand how Bernoulli and Newton apply, but I feel that the Magnus effect only applies to rotating cylinders and balls, not wings. As I understand Magnus; the boundary layer moves with the rotating cylinder on the top side, therefore entrailing other layers of passing air at increased velocities, and thus lower pressure exists on the top side of the object. The opposite effect takes place on the bottom of the object (the side advancing toward the relative wind) creating lower velocity and consequently higher pressure. So I can see how this applies to golf balls and rotating cylinders, but with planes the boundary layers are attached to a stationary wing... Yes, highs and lows are being created, and a stagnation point exists, but not for the reasons associated with Magnus and 'moving' boundary layers.  So am I misunderstanding the Magnus effect? Or does it actually apply to traditional airfoils?   Thanks Jon

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2 Answers

  1. Best Answer


    Dan S. on May 19, 2015

    Magnus effect is the actual “upward force” that results from low pressure on an airfoil. Bernoulli’s Principle explains WHY there is lower pressure on top of an airfoil, but is not the force itself that causes lift. That’s why it’s called Bernoulli’s Principle, not Bernoulli’s Force. The rotating cylinder is what scientists used to observe and measure this force back in days before airplanes where invented. So the rotating cylinder is not meant to be directly related to an airfoil (although it illustrates the principle), but was the tool used by early scientists to measure Magnus force. It also illustrates the point that air has a certain viscosity, and that there is friction between the surface of the cylinder (or airfoil) and air itself.

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  2. jon sanderson on May 22, 2015

    Thanks Dan. The way it reads in the PHAK is a little ambiguous to me. I assumed that the Magnus effect was directly related to the rotating object and the skin friction effects, not just the high/low pressure effects.

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