On Thu, 12 Dec 2002, Peter Rathmann wrote: > > If this is true can we also infer that no energy is being used to keep a > > plane in the air that is flying straight and level (other than that required > > to overcome friction-or the sound wave barrier)? > > Yes, that is correct. If you calculate the power required for level > flight it is just based on the amount needed to overcome the drag forces > on the plane (power of level flight = speed times horizontal drag > force). There is no extra component for overcoming gravity unless the > plane is rising. Does the term "induced drag" mean anything to you? It's the drag that is created as a direct result of producing lift. And you need lift to overcome gravity. It's not drag in the convential sense of friction - that is called "parasite drag" in aerodynamics. Induced drag is small at high airspeeds, but can get very large at low airspeeds, near the stall, much larger than parasite (friction) drag when slow. Induced drag is *precisely* the extra component necessary for overcoming gravity, even in level or descending flight (not free fall). *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Thu Dec 12 2002 - 10:00:43 PST
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