On Fri, 19 Nov 2004 at 16:21:11 in message
, Bill Denton
wrote:
No, not a trick question...

You CAN'T take off without a stall, if an airfoil only has two states:
flying or stalled.

If you admit you have only a limited knowledge why start off with a
categorical statement? This indicates that you do not yet understand
what an airfoil stall is. A stall occurs when the angle of attack of an
airfoil exceeds a limit beyond which lift falls rather than increases.
This angle would not normally ever be exceed in a take off. [1]

If the airfoil is flying you cannot take off, and if it's not flying it's
stalled.

I suppose you mean above that if an aircraft is already flying it must
have already taken off! Certain amount of truth in that but your second
phrase is definitely wrong. See [1]

(There's a whole bunch of physics involved here that I don't yet know, so
anyone, please feel free to correct whatever I get wrong.)

Fine but the purchase of an elementary book on aerodynamics would be a
good start. You cannot expect a complete course on elementary
aerodynamics by asking questions which to me, sound as if you are not
really seeking elucidation.

You stated: "It's flying as soon as you start moving on the runway". That is
not correct. It doesn't begin to fly until you develop enough relative wind
to create enough lift to overcome drag. If an airplane is only moving at 1
kt. down a runway, it is probably not flying.


While 'it's flying as soon as you start moving on the runway' is not an
ideal way of putting it the rest of your paragraph suggests that you do
not yet understand the difference between lift and drag. Your third
sentence is another categorical statement which is also wrong.

Lift is a force generated at right angles to the airflow and drag is a
force along the direction of the airflow. Since they act at right angles
to each other lift is not a force that 'overcomes drag'. Your fourth
sentence is correct when you talk about the whole aircraft but not if
you are just talking about an airfoil..

And an aircraft will not land until it has reached a "stalled" state.

Thus misconception of either or both of 'landing and stall' has already
been dealt with in this thread.
--
David CL Francis