Wind Speed Over a Wing

If you’ve been looking into flight training for a while, you’ve likely heard some derivation of the following: “air must move over the top of the wing faster to meet the wind that flows under the wing at the same time.”  Well, I always wondered why the wind “must” meet at the same time.  It turns out, it need not do so.  The following video briefly shows that the wind over the top of a wing does move faster than the wind beneath the wing.  However, the wind over the top of the wing also arrives at the end of the wing much sooner than that of the wind that travels beneath the wing. [Read more…]

Bernoulli’s Principle of Pressure

Bernoulli’s Principle of Pressure states that the pressure of a moving fluid (liquid or gas) varies with its speed of motion (1).  If the fluid’s speed increases, a drop in pressure will be seen.  This principle is a key component of flight.  It is used as a basis for the measurement of airspeed and for analyzing the airfoil’s ability to produce lift (1).


Air Pressure Decreasing in a Venturi Tube

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Air Density

The Atmosphere

Your aircraft will be flying through atmosphere at a certain elevation, so we might as well start there.  Think back to your early science classes when you were taught about the environment.  You may not remember the exact mixture, but I’m sure you recall that our atmosphere is a mixture of gases.  What you might not recall is that gases have weight, and are thus subject to the laws of physics.  Thus, we can determine some basic facts about the air based on the temperature, humidity, and pressure of the air.  Why is this important?  Because temperature, humidity, and pressure affect air density – and air density is a key component of aircraft performance!

Density Decreases with Altitude (Generally)

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