Angle of attack

Bill Daniels wrote:

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

snip

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.

While I agree with Bill that stalling the wing is a proximate cause of
stall/spin accidents, I don't understand his conclusion that getting
pilots to understand angle of attack (AOA) will help a lot (or even at
all). The big problem is AOA is an abstract engineering parameter,
because pilots can't see it, can't hear it, and can't feel it. We can
see attitude and airpeed, we can hear airspeed and stall rumble, and we
can feel stick position and stick forces, so that is what we use to fly
by. I sure don't think about AOA when I'm flying.

IF we had a "good" AOA indicator or pre-stall indicator, THEN we might
be able to fly more safely using it. And that is something the soaring
community has wanted for decades, but so far, we don't have any in wide
use. So, I think we need people to experiment with currently available
AOA units, like Safeflight's and DG's. If they seem useful, try them on
students, and see if students learn fly more safely or more quickly. If
AOA indicators seem promising, it might lead to better/cheaper
indicators, and begin to spread throughout the fleet.

Until we can hear it, see it, or feel it, we won't be able to use.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

On Dec 13, 2:16 am, "Bert Willing" bw_no_spam_ple...@tango-
whisky.com wrote:

... Nose attitude is the onboard AoA, and it works...

Apologies for the dogpile, but I think that's wrong and wrong. I
believe that thinking like that is exactly what leads to the types of
insidious stall/spin entries that most often become accidents.

That's not to say that nose angle isn't a useful tool. In straight-and-
level flight, and in stable coordinated turns, nose angle and nose
angle rate are key indicators of speed and acceleration.

However, straight-and-level flight and stable coordinated turns
constitute a very small subset of the available flight regimes, and
are among those least likely to offer unanticipated stall spin
entries.

Also, in flapped ships, and especially in glidepath-flapped ships,
nose angle is virtually useless as a speed reference independent of
flap deflection. In a good old HP glider, you can have your toes on
the horizon and be tearing along at a stable 80 kts. Or you can be
going almost straight down at a stable 80 kts and viewing the horizon
through the crown of the canopy.

So far as soaring and sailplanes go, I'm basically an anti-
gadgetarian. For years, the most complicated device in my ship was the
digital clock. However, I think that a simple, effective AOA indicator
with an intuitive display would be a real asset. And, it would be
useful not only for stall/spin protection but also for cruise and
thermal optimization.

Thanks, Bob K.

I'm getting pretty tired of all this "Angle of Attack" business.

As a pacifist (I abhor violence when it's directed at me) I would prefer we
use the term, "Angle of Retreat" instead.

Remember, fly the tail, the wing will take care of itself.

bumper
"Dare to be different . . . circle in sink."
zz
Minden
purveyor of Quiet Vents and MKII (non AOA) yaw strings.
"Bob Kuykendall" wrote in message
...
On Dec 13, 2:16 am, "Bert Willing" bw_no_spam_ple...@tango-
whisky.com wrote:

... Nose attitude is the onboard AoA, and it works...

Apologies for the dogpile, but I think that's wrong and wrong. I
believe that thinking like that is exactly what leads to the types of
insidious stall/spin entries that most often become accidents.

That's not to say that nose angle isn't a useful tool. In straight-and-
level flight, and in stable coordinated turns, nose angle and nose
angle rate are key indicators of speed and acceleration.

However, straight-and-level flight and stable coordinated turns
constitute a very small subset of the available flight regimes, and
are among those least likely to offer unanticipated stall spin
entries.

Also, in flapped ships, and especially in glidepath-flapped ships,
nose angle is virtually useless as a speed reference independent of
flap deflection. In a good old HP glider, you can have your toes on
the horizon and be tearing along at a stable 80 kts. Or you can be
going almost straight down at a stable 80 kts and viewing the horizon
through the crown of the canopy.

So far as soaring and sailplanes go, I'm basically an anti-
gadgetarian. For years, the most complicated device in my ship was the
digital clock. However, I think that a simple, effective AOA indicator
with an intuitive display would be a real asset. And, it would be
useful not only for stall/spin protection but also for cruise and
thermal optimization.

Thanks, Bob K.

Hey Bob, quick question for you...I seem to recall hearing during
powered flight training that says a wing will always stall at a fixed
angle of attack, regardless of what the airspeed is. I think it was
said this is regardless of loading, airspeed, etc. If this IS true, AoA
indicators might be useful, especially if an indicator is on the
instrument panel and maybe, if it were a simple bar graph of different
colored LEDs, one could calibrate it to give an audible stall warning
horn...whatcha think???

Scott
Corben Junior Ace (limited glider time!)

Bob Kuykendall wrote:
On Dec 13, 2:16 am, "Bert Willing" bw_no_spam_ple...@tango-
whisky.com wrote:


... Nose attitude is the onboard AoA, and it works...


Apologies for the dogpile, but I think that's wrong and wrong. I
believe that thinking like that is exactly what leads to the types of
insidious stall/spin entries that most often become accidents.

That's not to say that nose angle isn't a useful tool. In straight-and-
level flight, and in stable coordinated turns, nose angle and nose
angle rate are key indicators of speed and acceleration.

However, straight-and-level flight and stable coordinated turns
constitute a very small subset of the available flight regimes, and
are among those least likely to offer unanticipated stall spin
entries.

Also, in flapped ships, and especially in glidepath-flapped ships,
nose angle is virtually useless as a speed reference independent of
flap deflection. In a good old HP glider, you can have your toes on
the horizon and be tearing along at a stable 80 kts. Or you can be
going almost straight down at a stable 80 kts and viewing the horizon
through the crown of the canopy.

So far as soaring and sailplanes go, I'm basically an anti-
gadgetarian. For years, the most complicated device in my ship was the
digital clock. However, I think that a simple, effective AOA indicator
with an intuitive display would be a real asset. And, it would be
useful not only for stall/spin protection but also for cruise and
thermal optimization.

Thanks, Bob K.

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

By Golly---I think you are on to something here!
See post by Mike Borgelt on the other, related, thread.

Hartley Falbaum
KF Georgia USA


"bumper" wrote in message
...
I'm getting pretty tired of all this "Angle of Attack" business.


Remember, fly the tail, the wing will take care of itself.

bumper
"Dare to be different . . . circle in sink."
zz
Minden
purveyor of Quiet Vents and MKII (non AOA) yaw strings.

Scott,

It is true. A wing stalls for a given angle of attack for a given flap
setting. It is not dependent on wing loading, attitude, etc. The index
system you described exists on US Naval aircraft. Depending on the
aircraft, it is either mounted on the glare shield or the HUD. In either
case, it is visible while looking out the windscreen. In addition an
external set of lights showing AOA are placed such that they can be seen by
the LSO (Landing Signals Officer) on the flight deck.

Of all the instruments in the A-3B and A-6A , the AOA is the only one I
would like to add to my HP-14.

Wayne
HP-14 "6F"
http://www.soaridaho.com/Schreder/HP-14/N990/N990.html



"Scott" wrote in message
.. .
Hey Bob, quick question for you...I seem to recall hearing during powered
flight training that says a wing will always stall at a fixed angle of
attack, regardless of what the airspeed is. I think it was said this is
regardless of loading, airspeed, etc. If this IS true, AoA indicators
might be useful, especially if an indicator is on the instrument panel and
maybe, if it were a simple bar graph of different colored LEDs, one could
calibrate it to give an audible stall warning horn...whatcha think???

Scott
Corben Junior Ace (limited glider time!)

Bob Kuykendall wrote:
On Dec 13, 2:16 am, "Bert Willing" bw_no_spam_ple...@tango-
whisky.com wrote:


... Nose attitude is the onboard AoA, and it works...


Apologies for the dogpile, but I think that's wrong and wrong. I
believe that thinking like that is exactly what leads to the types of
insidious stall/spin entries that most often become accidents.

That's not to say that nose angle isn't a useful tool. In straight-and-
level flight, and in stable coordinated turns, nose angle and nose
angle rate are key indicators of speed and acceleration.

However, straight-and-level flight and stable coordinated turns
constitute a very small subset of the available flight regimes, and
are among those least likely to offer unanticipated stall spin
entries.

Also, in flapped ships, and especially in glidepath-flapped ships,
nose angle is virtually useless as a speed reference independent of
flap deflection. In a good old HP glider, you can have your toes on
the horizon and be tearing along at a stable 80 kts. Or you can be
going almost straight down at a stable 80 kts and viewing the horizon
through the crown of the canopy.

So far as soaring and sailplanes go, I'm basically an anti-
gadgetarian. For years, the most complicated device in my ship was the
digital clock. However, I think that a simple, effective AOA indicator
with an intuitive display would be a real asset. And, it would be
useful not only for stall/spin protection but also for cruise and
thermal optimization.

Thanks, Bob K.

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

If they're good enough for the squids, they're good enough for me!

When I was in the USAF, I think I recall seeing moveable vanes on the
side of the fuselage on C-135 types (I assume they were AoA senders)...

Scott

Wayne Paul wrote:
Scott,

It is true. A wing stalls for a given angle of attack for a given flap
setting. It is not dependent on wing loading, attitude, etc. The index
system you described exists on US Naval aircraft. Depending on the
aircraft, it is either mounted on the glare shield or the HUD. In either
case, it is visible while looking out the windscreen. In addition an
external set of lights showing AOA are placed such that they can be seen by
the LSO (Landing Signals Officer) on the flight deck.

Of all the instruments in the A-3B and A-6A , the AOA is the only one I
would like to add to my HP-14.

Wayne
HP-14 "6F"
http://www.soaridaho.com/Schreder/HP-14/N990/N990.html



"Scott" wrote in message
.. .

Hey Bob, quick question for you...I seem to recall hearing during powered
flight training that says a wing will always stall at a fixed angle of
attack, regardless of what the airspeed is. I think it was said this is
regardless of loading, airspeed, etc. If this IS true, AoA indicators
might be useful, especially if an indicator is on the instrument panel and
maybe, if it were a simple bar graph of different colored LEDs, one could
calibrate it to give an audible stall warning horn...whatcha think???

Scott
Corben Junior Ace (limited glider time!)

Bob Kuykendall wrote:

On Dec 13, 2:16 am, "Bert Willing" bw_no_spam_ple...@tango-
whisky.com wrote:



... Nose attitude is the onboard AoA, and it works...


Apologies for the dogpile, but I think that's wrong and wrong. I
believe that thinking like that is exactly what leads to the types of
insidious stall/spin entries that most often become accidents.

That's not to say that nose angle isn't a useful tool. In straight-and-
level flight, and in stable coordinated turns, nose angle and nose
angle rate are key indicators of speed and acceleration.

However, straight-and-level flight and stable coordinated turns
constitute a very small subset of the available flight regimes, and
are among those least likely to offer unanticipated stall spin
entries.

Also, in flapped ships, and especially in glidepath-flapped ships,
nose angle is virtually useless as a speed reference independent of
flap deflection. In a good old HP glider, you can have your toes on
the horizon and be tearing along at a stable 80 kts. Or you can be
going almost straight down at a stable 80 kts and viewing the horizon
through the crown of the canopy.

So far as soaring and sailplanes go, I'm basically an anti-
gadgetarian. For years, the most complicated device in my ship was the
digital clock. However, I think that a simple, effective AOA indicator
with an intuitive display would be a real asset. And, it would be
useful not only for stall/spin protection but also for cruise and
thermal optimization.

Thanks, Bob K.

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




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

Originally Posted by Tony Verhulst

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

What about "Extraordinary Popular Delusions and the Madness of Crowds"? That's still in print...

On Dec 14, 5:41 am, Chris Wells Chris.Wells.
wrote:

What about "Extraordinary Popular Delusions and the Madness of
Crowds"? That's still in print...

In print? Heck, this is RAS. We practice it daily here.

Bob K.

Until I read the book 'Ruder and Stick' I thought you can not hear the
AoA. But now I know that I can hear large changes in the AoA. Just turn
down the radio and the variometer and listen to your glider when you are
flying at different AoA at the same speed. You will realize marked
differences in sound of your gilder. Our Duo sounds different at
thermaling AoA and at stall AoA. The sound at stall AoA is much deeper
than at thermaling AoA.

You can feel the distance to the stalling AoA in the elevator. If you
are far away from the stall AoA a small increase in back pressure on the
stick will lead to a much larger change of the attitude than at an AoA
close to stall speed.

Unfortunately we train our students in practical flying for attitude
controlled flight. This is a very successful strategy to reach an
intended equilibrium speed in calm air if a slow control loop is
sufficient to reach the equilibrium. But it is not a very good technique
to fly in the turbulent air close to a ridge. There as in winch launch
we train to rely more in the ASI, but again this is just a successful
technique, if a slow control loop is sufficient to reach the equilibrium.

It would be much better to have a fast AoA in the glider and to use it
in the control loop, because it would tell you all the time how far you
are away from the stalling AoA.


Eric Greenwell schrieb:
Bill Daniels wrote:

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

snip

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.

While I agree with Bill that stalling the wing is a proximate cause of
stall/spin accidents, I don't understand his conclusion that getting
pilots to understand angle of attack (AOA) will help a lot (or even at
all). The big problem is AOA is an abstract engineering parameter,
because pilots can't see it, can't hear it, and can't feel it. We can
see attitude and airpeed, we can hear airspeed and stall rumble, and we
can feel stick position and stick forces, so that is what we use to fly
by. I sure don't think about AOA when I'm flying.

IF we had a "good" AOA indicator or pre-stall indicator, THEN we might
be able to fly more safely using it. And that is something the soaring
community has wanted for decades, but so far, we don't have any in wide
use. So, I think we need people to experiment with currently available
AOA units, like Safeflight's and DG's. If they seem useful, try them on
students, and see if students learn fly more safely or more quickly. If
AOA indicators seem promising, it might lead to better/cheaper
indicators, and begin to spread throughout the fleet.

Until we can hear it, see it, or feel it, we won't be able to use.