No One Can Explain Why Planes Stay in the Air

If you are a flight instructor or just the explainer in your family you may have struggled with illuminating your students, family, or passengers of why airplanes fly. You may have used one of the commonly used theories like the Bernoulli principle, which explains how low pressure is created above a cambered airfoil but fails to explain why the same wing can still support the aircraft during inverted flight or why there is higher pressure below the airfoil. There is the competing Newton’s third theorem a.k.a. action causing a reaction, which explains how a barn door can produce lift but does not explain the differential pressure above and below an airfoil. No lesser than the venerable Peter Garrison expressed his frustration over the lack of a comprehensive theory of why airplanes fly (You Will Never Understand Lift. Peter Garrison in Flying; June 4, 2012). Just recently, SCIENTIFIC AMERICAN published an article that reviews the current views on aerodynamics and both the mathematical and engineering approaches that make aerodynamics a predictive science. It turns out that there are four complementing theories that together can explain the behavior of air around an airfoil. Neither of them can alone explain all aspects of lift but together they inform engineers of how to design an airfoil with predictable properties. Do you need to be an expert on the subject to be a better pilot? The answer is probably ‘no’ but some understanding of the topic will help you to better explain what the effects of flaps, slats, slots, spoilers, stall strips and vortex generators are.
In the final analysis you may believe that aerodynamics has nothing to do with what creates lift: it is, in fact, money that makes airplanes fly.

The author of the article, Ed Regis, has written 10 popular science books and has also logged 1,000 hours flying time as a private pilot.

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