Page 28 - Understanding Flight

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CHAPTER

How Airplanes Fly

s mentioned in the introduction of this book, a great deal of false
concepts and “mythology” have built up around the principles of
Aflight. In this chapter we explain with simple logical discussions
the physical phenomena of lift and address some of the errors in the
present explanations. Armed with an understanding of lift, we take it
further and give you an intuitive understanding of flight in a much
broader sense. We start by looking at three descriptions of lift.

The Popular Description of Lift

Most of us have been taught what we will call the “popular descrip-
tion of lift,” which fixates on the shape of a wing. The key point of
the popular description of lift is that the air accelerates over the top
of the wing. Because of the Bernoulli effect, which relates the speed
of the air to the static pressure, a reduced static pressure is produced
above the wing, creating lift. The missing piece in the description is
an understanding of the cause of the acceleration of the air over the
top of the wing. A clever person contributed this piece with the intro-
duction of the “principle of equal transit times,” which states that the
air that separates at the leading edge of the wing must rejoin at the

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