onsdag 26 september 2012

Incorrect Fundamentals of Aviation

The book Fundamentals of Aviation and Space Technology, published by University of Illinois/Urbana in 1962, is presented as follows:
  • The reception accorded the first edition of this book under its present title was very gratifying. It appealed especially to teachers and students, as well as to the  air transportation industry for orientation courses. 
  • The continued success of the book has again exhausted the supply, and a new printing is necessary only two years after the previous revision.
As an apparently very successful example of a university level educational text, let us check how the Theory of Flight is presented in Chapter 3. It starts out
  • Whenever, in casual conversation, a group of people start to discuss airplanes, someone is almost certain to exclaim, "Why, some of those airplanes weigh tons. I don't see how they stay in the air." Very few people understand the forces that control an airplane in flight. 
  • For many years engineers have studied the motion of air over airplane parts in order to learn how a change in the shape of the part affects the force created on it by the moving air. Although a large amount of information is presently available on this subject, the desire to make airplanes go higher, faster, farther, and carry greater loads requires continuous research.
Then follows the "equal transit time" theory = Incorrect theory #1 identified by NASA:
  • If we move the wing through the air at a relatively high speed with the rounded or leading edge forward, the following things happen: The blunt and thick leading edge pushes the air out of the way. Part of this displaced air flows rapidly (the speed is important) over the wing and part of it flows under the wing. The layers of air, after going over and under the wing, join again behind the trailing edge. 
  • The important thing to remember is that due to the curved upper surface the air that flowed over the wing had to go farther than the air that went under the wing. 
  • Consequently, air that flowed over the wing had to travel faster than the air that went under the more or less flat bottom surface. 
  • The air which had to travel farther across the top of the wing is stretched out and becomes thinner, creating a reduced pressure on the upper surface. 
  • The air traveling along the bottom of the airfoil is slightly compressed, and consequently develops increased pressure. 
  • The difference in pressure between the air on the upper and lower surfaces of the wing, when exerted on the entire wing area, produces lift. 
But this was 50 years ago, you may say: It cannot be true that books of today continue to teach theories of flight which are known to be incorrect.

But then you are wrong! There is no current text-book which teaches a correct theory of flight. It is now time  to rewrite text-books to teach the New Theory of Flight.

PS Checking pageview statistics of this blog I see that the interest in understanding what keeps airplanes in the air appears to be close to nil. Can it be that 100 years of incorrect theories has ruined the subject? If so, it is now high time for revival of the keen interest 100 years ago from the pioneers of aviation.

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