2FlyAgain Posted July 18, 2013 Report Share Posted July 18, 2013 Greetings, The recent discussion of angle of attack in another thread contained a mention of Bernoulli's principle. I suspect that practically all of us were taught Bernoulli's principle as the explanation of lift for airplane wings. About a decade ago, I ran across an argument that Bernoulli's principle was an inadequate description and that the Coanda effect was a better explanation. I have attached the 16 page article for those that are interested. Briefly, an everyday observation of the Coanda effect can be seen observing water running from the kitchen faucet. Without an obstruction to the flow, the water runs straight down. When a curved object (e.g. a round glass held horizontally) is placed just barely into the water flow, the water curves around the object and direction of the flow changes from straight down. The authors argue that for airplane wings the air flow coming off the trailing edge of the wing is not parallel to the bottom of the wing (Bernoulli thinking) but rather deflected downward at an angle roughly equal to the angle of attack. The force of the downward component (vector) of the airflow off the wing creates an equal an opposite reaction that lifts the wing upward according to Newton's third law. This explanation makes a sense according to my first year college physics. The authors go on to elaborate that this explanation is consistent with wing efficiency, wing loading, power changes, drag effects, wing tip vortices and ground effect. Since many readers of this forum seem to value both the true explanation for a phenomena and a good debate, I thought that I would offer this as food for thought... My thanks to all of you for the many stimulating discussions on this forum! Enjoy (...or not) Link to comment Share on other sites More sharing options...
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