Recently, Peter Duniho posted:

"Neil Gould" wrote in message
I wasn't claiming that it does. It's just that the amount of lift
after stall isn't sufficient to be relevant.

That's a false claim. As the lift drops off in a continuous manner,
there is a region "after stall" where the lift coefficient is just as
high as usable regions "before stall".

You may equivocate on whether a pilot can maintain the airplane at the
angle-of-attack required to obtain that "after stall" coefficient of
lift. But the fact remains that the lift is theoretically obtainable.
As long as you don't want a lift coefficient very close to the
maximum lift coefficient for the wing, it may not even be that hard
to obtain the desired coefficient.

Again, the _context_ is a response to Matt & Jose's claim of controlling a
typical SEL to "greaser full-stall landings". I was agreeing with George
that this is probably not what they were experiencing, and Todd's
explanation regarding the high pitch angle typical of stall speeds is in
agreement with this, albeit for other reasons. So, in context, how is your
theoretically available lift relevant?

When one refers to the "angle of attack" (and, yes, I know that
"AOA" is the acronym), one is definitely referring to motion having
both direction and magnitude.

No, they are not. The angle-of-attack is a specific angle, measured
between the wing's chord and the relative wind. In fact, a
motionless airplane can still have an angle-of-attack, just as long
as there is some wind.

If there is wind, there is motion, direction and magnitude relative to the
wing, ergo, a vector. If there is no wind, there is no "attack", and that
angle then describes something entirely different.

[...]
However, it would have been better stated if I had said "...
relative direction of _the wing's_ travel...", even though the
typical SEL's wing pitch isn't drastically different from the rest
of the aircraft. ;-)

The angle of incidence (which is what you appear to be talking about
now...that is, the angle between the wing chord and the longitudinal
axis of the airplane) is yet again something else entirely different
from angle-of-attack.

Two different things are being described. In context (the direction of
travel), the difference between the AOA and the angle of incidence is not
"drastically different".

[...]
The confusion here is not between the airplane's pitch angle and the
wing's angle-of-attack. It's your insistence on calling the
angle-of-attack a vector, when it's a scalar (and, it appears, your
confusion between "relative wind" and "angle-of-attack").

To be a scalar, it would have to lack motion, ergo no "attack".

[...]
I responded to that. In the context of landing, if one flies slowly
enough to stall, one can stall "flat" relative to the ground because
the decrease in forward "relative wind" increases the AOA. That is
what my remark addresses.

Your claim is incorrect. As long as the airplane is flying just
above the ground, the relative wind is parallel to the ground. No
change in the angle-of-attack will occur from any decrease in speed,
not directly.

My claim is that if the aircraft is flying parallel to the ground just
before touch-down, it isn't stalled.

[...]
It is simply impossible to do what you suggest one might do. If one
"flies slowly enough to stall", the angle-of-attack is at the stalling
angle-of-attack, period.

And all I'm saying is that this is independent of the pitch angle relative
to the ground.

[...]
What WILL happen is that as the aircraft slows, the pitch angle of the
aircraft will need to be increased, so as to continually increase the
angle-of-attack of the wing.

We are describing the same phenomena from two perspectives. In the context
of my usage, if one maintains the pitch angle as the aircraft slows, the
AOA will continually increase (normally, the pitch angle changes as the
aircraft slows). But, again, the context of what happens during landing;
one is maintaining a safe pitch angle as the aircraft slows, not
necessarily increasing the pitch angle to insure a stall.

[...]
In *either* case, the
airplane will touch the runway before the wing stalls, assuming a
safe landing.

In fact, I stated that the risk is something quite different from a safe
landing.

Neil