Newtons Laws Explain How Frisbees Fly



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Submitted May 12, 2020
Published Jul 13, 2020
10.24018/ejphysics.2020.2.4.9

Abstract viewed = 2907 times

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Newtonian mechanics explain the physics of how frisbees fly. Specifically, a frisbee in horizontal flight with a positive angle of attack (AOA), will fly through a static mass of air each second (‘m/) that it accelerates to a velocity (’a’) downwards, to create a downward force (Force = ma), due to Newtons 2nd law of motion. The ‘equal & opposite’ upward force generated (Newtons 3rd law of motion), provides an upward force and vertical lift. Air goes down and the frisbee goes up. It’s that simple.

There are two airflows: The underside of the frisbee pushes air down. While the curved topside of the frisbee pulls air downwards due to the Coanda effect. This explanation is different to other theories of lift currently available, such as those based on fluid mechanics (Bernoulli and Navier-Stokes) and vortices.

The spin on a frisbee enhances the stability of flight due to the gyroscopic effects. In turn, stability of flight allows the frisbee to generate laminar (smooth) airflows, and thus better lift. The spin itself does not directly contribute towards lift. In addition, airflow vortices account for trick throws, where the frisbee appears to defy normal physics.

So what? This provides new insight into lift and flight not currently found in accepted physics textbooks. The best performing frisbee will be one that maximises the Coanda effect on the topside of the disc; to increase the amount of air displaced down. Newtons laws can explain why a frisbee thrown flat (small AOA) generates better lift and will fly further than a frisbee thrown high, on a parabolic type of path. This explanation of lift can also be applied to airplane wings.

Keywords: Aerodynamic lift; buoyancy; Coanda effect; frisbee; Newton, physics;

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