Thread: Stalls
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Old 09-25-2007, 04:31 PM
  #9  
POPA
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Joined APC: Jul 2006
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Keep these definitions in mind:
Relative wind is the flow of air directly opposite the direction the aircraft is traveling (which is NOT necessarily the same way the nose is pointed!). If you want a good illustration of the difference between relative wind and pitch angle, look at the attitude indicator during slow flight. Although you're traveling at a fairly constant altitude, the nose is pitched up significantly.

Angle of attack is the angle between the aircraft's chordline and the relative wind.

Understanding these two concepts is imperative if you're going to understand stalls at any level.
An aircraft stalls at the critical angle of attack - that is, the AOA at which the wing no longer produces lift. This AOA is a constant number for all weights of the aircraft. The number referred to as a stall speed is a general speed at which you might expect the aircraft to stall. However, this speed changes as weight changes, as well as with different aircraft configurations (thus we have Vs1 and Vso).
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