This is an interesting topic. How exactly does the horizon give you
angle of attack reference? I don't have much experience in gliders yet,
but in powered airplanes, the horizon can be in a lot of different
places with reference to the nose. For example, the nose might be
slightly above the horizon at stall with engine at idle, a lot more
above the horizon at stall with full power and the horizon might be
straight above the cockpit while holding a stall in a spin. In a
powered plane, the nose can be right on the horizon, but airspeed may be
just above stall as you are "mushing" through the air (ie level attitude
with reference to horizon, but sinking at a high rate). I was taught
that angle of attack was the angular difference between the wing chord
line and the wind flow direction. I would think a simple AoA indicator
would be a string suspended below a wire about 1 to 2 feet out in front
of the wing with a panel outboard of the string with lines drawn
representing angles drawn with a protractor such as 0 degrees, 5
degrees, 12 degrees, etc.


Scott


Bert Willing wrote:
Sorry Bill,

I don't know how you train your students, but the training I received, and
the training I give, ALWAYS refers to the attitude of the nose in respect to
the horizon, NEVER to ASI readings.
Nose attitude is the onboard AoA, and it works.

If in your environment the reference is ASI reading, then indeed this would
be indeed chilling.

On a winch launch, nose attitude does not work, but ASI reference does work.
Limits need to be greatly corrected in respect to free flight, but if you
don't get below this limit, you won't crash - because the limit is such that
you simply can't reach critical AoA by staying above the limit.

Bert

"Bill Daniels" bildan@comcast-dot-net wrote in message
. ..

The threads on this subject has uncovered something that gives me chills.

Internationaly, gliding has an abominable safety record. Many fatal
accidents have as their root cause, failure by the pilot to maintain
flying speed or, stated more directly, control his angle of attack.
Clearly, based on these r.a.s threads on the subject, some do not
understand AOA in some fundamental way and that's chilling.

Controlling airspeed is simply not good enough - it's too abstract, too
easy to triviallize, too easy to misunderstand the significance of it.

Safety committees and organizations need to take this to hart. Here is a
root cause of our most dangerous accidents. The awareness of and
understanding of AOA has somehow slipped through the cracks. Slay this
dragon, and our accident numbers will look far better.

If the concept and practice of controlling angle of attack is not
absolutely ingrained in a pilot, the probability of an accident is
non-trivial - in fact, sooner or later, it's a near certainty. Awareness
of AOA should never be far from a pilots consiousness.

Controlling angle of attack is so fundamental to being a pilot that it's
staggering to think that it's possible to become one without it being
hammered into them until it's as instinctive as walking. Flying an
aircraft without this level of understanding is like being the captain of
a ship without understanding what makes it float.

As pilots, we do not fly the cockpit, the fuselage or the empenage - we
fly the wing. The wing is really the only thing that does fly, the rest
is just baggage.

Read Jim Webb's truly excellent book "Fly the wing".
http://www.amazon.com/Fly-Wing-James-Webb/dp/0813805414

Or equally good, Wolfgang Langewiesche's "Stick and Rudder". You can read
it free on line at Google Books.

Read these books - please! There is simply no subject in aviation that is
more fundamental or important to your survival.

Bill Daniels





--
Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)