måndag 17 september 2012

Incorrect Flight Theory in Flight and Motion Book

In the 641 page grand scale educational text Flight and Motion The History and Science of Flying, we read on How an Airplane's Wing Creates Lift:
  • The shape of a wing, curved on top and flatter underneath, is called an airfoil. 
  • When it slices through air, some of the air rises up over the curved top of the wing and down the other side. 
  • The air that travels over the top of the wing speeds up and, according to a scientific law known as Bernoulli’s Principle, the pressure above the wing falls. In addition, air flowing over the wing is directed downward by the wing’s shape. According to another scientific law, Newton’s third law of motion, this downward motion of the air results in an upward motion of the wing. 
  • The force that pushes a wing upward is lift. If a wing is tilted up at the front, air is deflected downward even more powerfully by the curved top and also by the angled bottom of the wing. This produces more lift.
In this description lift is somehow generated by the shape of the wing. As explanation it is empty of content. Circulation is not mentioned. The reason can be that it is considered to be too complicated for younger minds, although it is the correct explanation but has to be x-rated. Another reason is that an explanation by circulation is not convincing at all, not even to already educated minds. 

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