Angle of attack

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,

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)