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

DENIS SMITH wrote:

Very difficult to get out of!!  Maybe an aft cg
problem.  Not enough weight forward to force the
canard down far enough to get the main wing angle of
attack out of the stall regime.  Not good!!!

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