Angle of attack

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

I broached a subject on the http://soaringcanada.riq.ca/ The Round
Table but not with a direct question about A of A but more general, to
see what the response was. I tought it was interesting and revealing.
I ask "A question on minimizing stall accidents". I wanted to get a
sense of how this critical phase was being taught, in light of an
accident that happened just prior. If you want to see the answer you
my want to read some of the comments.
Udo




On Dec 11, 9:27 pm, "Bill Daniels" bildan@comcast-dot-net wrote:
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

On Dec 11, 6:27 pm, "Bill Daniels" bildan@comcast-dot-net wrote:
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

Bill,

You are wasting your breath, in this case several strokes of keys.

Jacek
Pasco, WA

Of course, it doesn't help that the AOA control is called an "elevator", leading one to believe that it makes you go up & down - I've also seen a zillion references in TV & the movies that reinforced this belief.

As far as I'm concerned, Stick & Rudder is the best book on piloting an aircraft ever written. I have a copy printed in 1944.

Udo wrote:
I broached a subject on the http://soaringcanada.riq.ca/ The Round
Table but not with a direct question about A of A but more general, to
see what the response was. I tought it was interesting and revealing.
I ask "A question on minimizing stall accidents". I wanted to get a
sense of how this critical phase was being taught, in light of an
accident that happened just prior. If you want to see the answer you
my want to read some of the comments.
Udo




On Dec 11, 9:27 pm, "Bill Daniels" bildan@comcast-dot-net wrote:
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.

When I went to collich in the U.S. (1967-1972), even though aeronautical
engineering (what I *really* wanted to major in) had morphed into
aerospace engineering (crummy commies), one forlorn airplane-based
course curricularly remained. Nonetheless, in that one (mostly a nearly
incomprehensible stability and control) aircraft-dominant course, it
became apparent to me that wings cared first about AoA, and only
secondarily about velocity of oncoming air. This was long before I'd
sat in a lightplane, seen a glider, or heard of (the very excellent)
"Stick and Rudder."

Soon after graduating, I bumbled into soaring, and the illness
permanently altered my life. Regrettably, I can no longer remember if
or how my instructor taught 'low speed flight' aspects. Can't remember
if he mentioned AoA, or if he merely said 'maintain flying speed.'

Doesn't matter, because the aforementioned course colored whatever my
instructor also conveyed.

In glider terms, if we assume compressibility isn't an issue (and it
isn't, for glider airspeeds), the wing cares Zero what speed your ASI
displays. Physically, it cares only about AoA of the oncoming air. Of
course, both are (through the stick) inter-related, but one (easier to
reliably measure) falls out in the wash, while the other (AoA),
physically determines what the wing is going to do next.

Now, (glider)pilot training reality demonstrably proves conceptual grasp
of the importance of AoA to the wing's immediate future actions (and
arguably, pilots' near-term lives) isn't required in order to obtain
one's pilot's license. Whether or not that's a good thing leads to this
thread's sort of 'religious arguments.' Fact is, cats can be skinned
multiple ways...

Personally, my brain is most comfortable understanding underlying
physical principles, even if it must (in part) rely on indirect
measurements (e.g. ASI, noise, 'feel,' etc.). I believe if a person
really and truly grasps the underlying physical principles governing the
consequences of his or her actions, s/he's more likely to do the
physically correct thing in moments of crisis, than not. Further,
s/he's less likely to (N.B. Key Word follows!) *inadvertently* go where
no thoughtful risk taker inadvertently wishes to go. (Kids, can you
spell "i*n-p*a*t*t*e*r*n s*t*a*l*l/s*p*i*n?")

Furthermore personally, I'd love to have an AoA gauge in my (flapped)
glider, even if NOT scientifically/numerically accurate. So long as
it's repeatable, I wouldn't care whether it showed my ship stalled at
10-degrees or 30-degrees AoA for 'whatever' flap deflection. That's the
difference between usable engineering accuracy, and scientific (e.g.
wind-tunnel-comparative) accuracy. Absence of the latter doesn't rule
out usefulness of the former.

'Reverently,'
Bob W.

As far as I'm concerned, Stick & Rudder is the best book on piloting
an aircraft ever written. I have a copy printed in 1944.

I've heard (but not verified) that, next to the bible, Stick And Rudder
has been in continuous publication longer than any other book. My 1972
edition has 40 pages on what it takes to turn an airplane - and it's 40
pages that you *want* to read. Get this book if don't have it already!

Tony V. CFIG

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

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)

Exibit "A" below. I couldn't come up with a better example of what I'm
talking about.

"Bert Willing" wrote in message
...
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

On Dec 13, 7:10 am, Scott wrote:
This is an interesting topic. How exactly does the horizon give you
angle of attack reference?

It does NOT give an angle of attack reference.

The pitch attitude (horizon) differs from AOA by the climb angle. See
http://www.av8n.com/how/htm/aoa.html for a good explanation.


While I agree that understanding of AOA is crucial for a pilot. I
don't think that a AOA indicator would be very useful in gliders.
(except for flight testing of a new design)

I think that stall accidents are caused by lack of awareness and lack
of attention. Letting the airspeed "creep away" and incorrectly
responding to the loss of airspeed. Substituting an AOA dial for the
airspeed dial, won't change that.


AOA gauges seem best suited for heavy aircraft flown by reference to
instruments. Where you might have to wait a couple of minutes after
setting the AOA and power lever to get the airspeed to respond.
Gliders will change their airspeed much quicker than a 747 or F-14.
We also only really fly at 2 or 3 different weights. No ballast, half
or full. So we only really have to remember the best L/D speed for
these conditions.

Todd Smith
3S