DENIS SMITH wrote:

 Sometimes we bury ourselves with numbers.  In the
 regime most of us fly a stall is defined by a
 situation where the angle of attack of a lifting (read
 wing) surface exceeds a point where smooth airflow is
 possible and separation of the airflow over the top of
 the wing causes loss of lift and that sinking
 sensation most of us have experienced.  The reason
 canard type aircraft claim to be stall proof is that
 the mechanism they use for pitch control has
 insufficient authority to put the wing at a high
 enough angle of attack to cause the wing to stall
 during normal (whatever that means) operations.
 Typically, angle of attack required to stall an
 airfoil is the same regardless of airspeed.  Your spam
 can will stall at 45, 100, or 150mph if that angle of
 attack is exceeded.  Whether it is caused by control
 input, wind shear, updraft, or whatever, it is angle
 of attack that is critical.  Paul is right that any
 airfoil can be stalled.  Usually the "Stall Proof"
 folks are just saying that whatever pitch mechanism
 they are using has insufficient authority to put the
 main airfoil at an angle of attack where a stall will
 occur.

Alfonso Lebron-Berges wrote:

I agree with this definition. Now, centering on the Canard issue, any
comments about "Deep stall"? I guess you fall in a more or less
stable attitude but fall anyway and if I am not wrong it is a very
difficult situation to ge out of.

Alfonso Lebrón-Bergés

 
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