would an AOA indicator be helpful in a glider?

[mooseknuckel1]

I am not a glider pilot, although I have been up with friends a few
times in the past, but I know the basic instrumentation is pretty
limited- and for good reason. However, would an AOA indicator increase
the efficency of gliding enough at best L/D, min sink and other
specific angles of attack enough to justify installing one? KIAS is
only an approximation of a desired angle of attack for a given weight,
so would a precise AOA indication be beneficial for glider pilots? In
most jets, speed tapes, stall protection systems and pitch limit
indicators are all based on AOA, and fight without them would be much
less efficent and safe. If there were a device to accurately display
the wings current AOA in flight and only cost around $100 would anyone
be interested in installing such a device. Thanks for any input or
opinions

[sisu1a]

> If there were a device to accurately display
> the wings current AOA in flight and only cost around $100 would anyone
> be interested in installing such a device. Thanks for any input or
> opinions


Some simply tape 'pitch strings' on the side of their canopy- much
less than $100, while others may spring for this system offered by
Safe Flight instruments:
http://www.safeflight.com/mmain.php?px=1&cm=3&cs=109&css=223 much
more than $100, Not pictured on their site is the rather nifty- but
prone to ground damage if not careful- little rotating vane that
attaches on the side of the fuselage that is at least easily removable
to reduce the likelyhood such damage incidents.

If you can improve on either of these options, there are indeed people
that would be interested. It would be particularly useful in winching
and other forms of ground launching more so than other aspects of
glider flying I think, but those who regularly utilize widely varying
wingloading would probably be into it as well.

So if you think can come up with a a better system than the string and
cheaper and more practical than the Safe Flight unit (one that does
not add undue drag of course) please pursue this.

-Paul

PS. if you search AOA on this group you will find there has been much
discussion already, so that would be a good place to start.

PPS. START FLYING GLIDERS!!

[sisu1a]

better link for Safe Flight AOA: http://www.safeflight.com/mmain.php?px=1&cm=3&cs=109&css=223

-Paul

[sisu1a]

On Jun 3, 1:10*pm, sisu1a > wrote:
> better link for Safe Flight AOA: *http://www.safeflight.com/mmain.php?px=1&cm=3&cs=109&css=223
>
> -Paul

oops.. here: http://www.safeflight.com/imgs/photos/Glider%20Sel%20Sheet%20Hort.pdf

[bildan]

On Jun 3, 1:34*pm, mooseknuckel1 > wrote:
> I am not a glider pilot, although I have been up with friends a few
> times in the past, but I know the basic instrumentation is pretty
> limited- and for good reason. However, would an AOA indicator increase
> the efficency of gliding enough at best L/D, min sink and other
> specific angles of attack enough to justify installing one? KIAS is
> only an approximation of a desired angle of attack for a given weight,
> so would a precise AOA indication be beneficial for glider pilots? In
> most jets, speed tapes, stall protection systems and pitch limit
> indicators are all based on AOA, and fight without them would be much
> less efficent and safe. If there were a device to accurately display
> the wings current AOA in flight and only cost around $100 would anyone
> be interested in installing such a device. Thanks for any input or
> opinions

Yes to all that. Here's another option developed for military UAV's
said to be quite accurate. http://www.cgmasi.com/aviation/index.html

This probe is just three brass tubes soldered together. The center
one is squared off and is the pitot tube. The top and bottom tubes
are cut at a 45 degree angle and connected to a differential pressure
transducer in an signal conditioning electronics package.

I think one of these could easily be fitted to the nose of a glider.

[pigro[_4_]]

On Wed, 3 Jun 2009 12:34:08 -0700 (PDT), mooseknuckel1
> wrote:

> However, would an AOA indicator increase
>the efficency of gliding enough at best L/D, min sink and other
>specific angles of attack enough to justify installing one?

Mostly, it would (greatly) improve safety. For an unflapped glider, a
string taped on the side of the canopy does the job sufficiently well.
For flapped gliders, things are more complicated; I guess the
electronic instrument cited by others, doesn't have an input for a
"flap lever position sensor" as well. But it should have one.

Aldo Cernezzi

[[email protected]]

On Jun 4, 2:38*am, pigro > wrote:
> On Wed, 3 Jun 2009 12:34:08 -0700 (PDT), mooseknuckel1
>
> > wrote:
> > However, would an AOA indicator increase
> >the efficency of gliding enough at best L/D, min sink and other
> >specific angles of attack enough to justify installing one?
>
> Mostly, it would (greatly) improve safety. For an unflapped glider, a
> string taped on the side of the canopy does the job sufficiently well.
> For flapped gliders, things are more complicated; I guess the
> electronic instrument cited by others, doesn't have an input for a
> "flap lever position sensor" as well. But it should have one.
>
> Aldo Cernezzi

At $100 and below you are probably at a sufficiently low price for
most. The other concerns will be power consumption (really should be
below 50mA to not be a concern given all the other electricity-hungry
stuff in a modern cockpit). Also configurability and readability will
be key. I'd think you'd want to integrate it with the airspeed
indicator (probably not practical), have an adjustment for flap
position and have some audio warnings, etc. Unless you want to do a
lot of flight testing work yourself, you'd probably need to allow the
customer to set alarms themselves based on various configurations.
Installation complexity could be an inhibitor as would anything that
looks like it might add even a small amount of drag.

9B

[bildan]

On Jun 3, 4:02*pm, bildan > wrote:
> On Jun 3, 1:34*pm, mooseknuckel1 > wrote:
>
> > I am not a glider pilot, although I have been up with friends a few
> > times in the past, but I know the basic instrumentation is pretty
> > limited- and for good reason. However, would an AOA indicator increase
> > the efficency of gliding enough at best L/D, min sink and other
> > specific angles of attack enough to justify installing one? KIAS is
> > only an approximation of a desired angle of attack for a given weight,
> > so would a precise AOA indication be beneficial for glider pilots? In
> > most jets, speed tapes, stall protection systems and pitch limit
> > indicators are all based on AOA, and fight without them would be much
> > less efficent and safe. If there were a device to accurately display
> > the wings current AOA in flight and only cost around $100 would anyone
> > be interested in installing such a device. Thanks for any input or
> > opinions
>
> Yes to all that. *Here's another option developed for military UAV's
> said to be quite accurate. *http://www.cgmasi.com/aviation/index.html
>
> This probe is just three brass tubes soldered together. *The center
> one is squared off and is the pitot tube. *The top and bottom tubes
> are cut at a 45 degree angle and connected to a differential pressure
> transducer in an signal conditioning electronics package.
>
> I think one of these could easily be fitted to the nose of a glider.

Adding a thought. I think the nose cone of most gliders would serve
as the probe. Just add a pair of air pressure ports top and bottom a
few inches aft of the nose and feed that pressure differential to the
signal conditioning electronics box.

[brianDG303[_2_]]

On Jun 4, 7:48*am, bildan > wrote:
> On Jun 3, 4:02*pm, bildan > wrote:
>
>
>
>
>
> > On Jun 3, 1:34*pm, mooseknuckel1 > wrote:
>
> > > I am not a glider pilot, although I have been up with friends a few
> > > times in the past, but I know the basic instrumentation is pretty
> > > limited- and for good reason. However, would an AOA indicator increase
> > > the efficency of gliding enough at best L/D, min sink and other
> > > specific angles of attack enough to justify installing one? KIAS is
> > > only an approximation of a desired angle of attack for a given weight,
> > > so would a precise AOA indication be beneficial for glider pilots? In
> > > most jets, speed tapes, stall protection systems and pitch limit
> > > indicators are all based on AOA, and fight without them would be much
> > > less efficent and safe. If there were a device to accurately display
> > > the wings current AOA in flight and only cost around $100 would anyone
> > > be interested in installing such a device. Thanks for any input or
> > > opinions
>
> > Yes to all that. *Here's another option developed for military UAV's
> > said to be quite accurate. *http://www.cgmasi.com/aviation/index.html
>
> > This probe is just three brass tubes soldered together. *The center
> > one is squared off and is the pitot tube. *The top and bottom tubes
> > are cut at a 45 degree angle and connected to a differential pressure
> > transducer in an signal conditioning electronics package.
>
> > I think one of these could easily be fitted to the nose of a glider.
>
> Adding a thought. *I think the nose cone of most gliders would serve
> as the probe. *Just add a pair of air pressure ports top and bottom a
> few inches aft of the nose and feed that pressure differential to the
> signal conditioning electronics box.- Hide quoted text -
>
> - Show quoted text -

You might find the DYNON AOA probe interesting:

http://www.dynonavionics.com/docs/D180_Feature_AOA.html

[[email protected][_2_]]

This has all been hashed out before (some interesting threads, those!)
but here is my 2 cents:

AOA can be derived from pressure differential, best way would be to
have sensor ports in both wings (enough to be redundant and avoid yaw
problems. Nose might also work, but it's the wing you care about,
really.

AOA is really only needed at high angles: Stall, Min Sink, L/D max,
recommended approach speed. Since these speeds vary with weight and
bank angle, AOA is better than airspeed. So to keep it simple, with
gear up show min sink (for thermalling) tied to flap setting, and
maybe have an index at L/D max (not really used that often). Gear
down, show desired approach speed, with warning approaching stall.

I think the military chevrons and doughnut indicator would work just
fine: On-speed (desired AOA) when center g(green) circle is lit.
Slightly slow when circle and lower up (red) chevron are both lit.
Slow when only red up chevron is lit, slightly fast when circle and
upper down (yellow) chevron is lit, and fast when only down chevron is
lit.

Electronics would need input from gear and flaps, if present, of
course.

Easy to see if on top of panel.

Kirk

[bildan]

On Jun 4, 10:25*am, " >
wrote:
> This has all been hashed out before (some interesting threads, those!)
> but here is my 2 cents:
>
> AOA can be derived from pressure differential, best way would be to
> have sensor ports in both wings (enough to be redundant and avoid yaw
> problems. *Nose might also work, but it's the wing you care about,
> really.
>
> AOA is really only needed at high angles: Stall, Min Sink, L/D max,
> recommended approach speed. *Since these speeds vary with weight and
> bank angle, AOA is better than airspeed. *So to keep it simple, with
> gear up show min sink (for thermalling) tied to flap setting, and
> maybe have an index at L/D max (not really used that often). *Gear
> down, show desired approach speed, with warning approaching stall.
>
> I think the military chevrons and doughnut indicator would work just
> fine: *On-speed (desired AOA) when center g(green) circle is lit.
> Slightly slow when circle and lower up (red) chevron are both lit.
> Slow when only red up chevron is lit, slightly fast when circle and
> upper down (yellow) chevron is lit, and fast when only down chevron is
> lit.
>
> Electronics would need input from gear and flaps, if present, of
> course.
>
> Easy to see if on top of panel.
>
> Kirk

I think Kirk's idea would work but it is generally accepted that an
accurate AoA probe should be as far forward of the wing and its near-
field flow effects as possible.

I don't think top and bottom nose pressure ports would be sensitive to
yaw since they should both be affected the same and cancel out cross
flow signals. A probe in the fuselage would have the advantage that
there wouldn't be anything to connect when rigging.

Clearly, there's a need for some experimentation.

[Andy[_9_]]

On Jun 4, 9:25*am, " >
wrote:
> This has all been hashed out before (some interesting threads, those!)
> but here is my 2 cents:
>
> AOA can be derived from pressure differential, best way would be to
> have sensor ports in both wings (enough to be redundant and avoid yaw
> problems. *Nose might also work, but it's the wing you care about,
> really.
>
> AOA is really only needed at high angles: Stall, Min Sink, L/D max,
> recommended approach speed. *Since these speeds vary with weight and
> bank angle, AOA is better than airspeed. *So to keep it simple, with
> gear up show min sink (for thermalling) tied to flap setting, and
> maybe have an index at L/D max (not really used that often). *Gear
> down, show desired approach speed, with warning approaching stall.
>
> I think the military chevrons and doughnut indicator would work just
> fine: *On-speed (desired AOA) when center g(green) circle is lit.
> Slightly slow when circle and lower up (red) chevron are both lit.
> Slow when only red up chevron is lit, slightly fast when circle and
> upper down (yellow) chevron is lit, and fast when only down chevron is
> lit.
>
> Electronics would need input from gear and flaps, if present, of
> course.
>
> Easy to see if on top of panel.
>
> Kirk

I think the tricky part will be calibration. The device needs to be
set up to a fraction of a degree so I suspect you'll have to do some
fancy measuring of a series of flight tests. You'll also need some
data from the factory about lift coefficient versus alpha.

9B

[bildan]

On Jun 4, 11:13*am, Andy > wrote:
> On Jun 4, 9:25*am, " >
> wrote:
>
>
>
> > This has all been hashed out before (some interesting threads, those!)
> > but here is my 2 cents:
>
> > AOA can be derived from pressure differential, best way would be to
> > have sensor ports in both wings (enough to be redundant and avoid yaw
> > problems. *Nose might also work, but it's the wing you care about,
> > really.
>
> > AOA is really only needed at high angles: Stall, Min Sink, L/D max,
> > recommended approach speed. *Since these speeds vary with weight and
> > bank angle, AOA is better than airspeed. *So to keep it simple, with
> > gear up show min sink (for thermalling) tied to flap setting, and
> > maybe have an index at L/D max (not really used that often). *Gear
> > down, show desired approach speed, with warning approaching stall.
>
> > I think the military chevrons and doughnut indicator would work just
> > fine: *On-speed (desired AOA) when center g(green) circle is lit.
> > Slightly slow when circle and lower up (red) chevron are both lit.
> > Slow when only red up chevron is lit, slightly fast when circle and
> > upper down (yellow) chevron is lit, and fast when only down chevron is
> > lit.
>
> > Electronics would need input from gear and flaps, if present, of
> > course.
>
> > Easy to see if on top of panel.
>
> > Kirk
>
> I think the tricky part will be calibration. *The device needs to be
> set up to a fraction of a degree so I suspect you'll have to do some
> fancy measuring of a series of flight tests. You'll also need some
> data from the factory about lift coefficient versus alpha.
>
> 9B

Actually, calibration is the easy part. Just load the glider to
maximum gross weight, fly it at the Calibrated Air Speed (From tables
in the POH) for best L/D, for minimum sink and for stall and note the
readings for each. You probably don't care about actual AoA is in
degrees.

If you want a fancy color LED display that changes color/shape
precisely at each, the electronics package should have adjustments
built in.

Alternatively, choose a 10 element LED bargraph display where each
element can be red, yellow or green depending on which pins are used.
Once the position of each AoA of interest is known, switch pins to
produce the color desired. You can also wire in a warning horn to
sound when the red stall LED lights up and the gear is down.

[Mike Bamberg]

On Jun 4, 11:22*am, bildan > wrote:
> On Jun 4, 11:13*am, Andy > wrote:
>
>
>
>
>
> > On Jun 4, 9:25*am, " >
> > wrote:
>
> > > This has all been hashed out before (some interesting threads, those!)
> > > but here is my 2 cents:
>
> > > AOA can be derived from pressure differential, best way would be to
> > > have sensor ports in both wings (enough to be redundant and avoid yaw
> > > problems. *Nose might also work, but it's the wing you care about,
> > > really.
>
> > > AOA is really only needed at high angles: Stall, Min Sink, L/D max,
> > > recommended approach speed. *Since these speeds vary with weight and
> > > bank angle, AOA is better than airspeed. *So to keep it simple, with
> > > gear up show min sink (for thermalling) tied to flap setting, and
> > > maybe have an index at L/D max (not really used that often). *Gear
> > > down, show desired approach speed, with warning approaching stall.
>
> > > I think the military chevrons and doughnut indicator would work just
> > > fine: *On-speed (desired AOA) when center g(green) circle is lit.
> > > Slightly slow when circle and lower up (red) chevron are both lit.
> > > Slow when only red up chevron is lit, slightly fast when circle and
> > > upper down (yellow) chevron is lit, and fast when only down chevron is
> > > lit.
>
> > > Electronics would need input from gear and flaps, if present, of
> > > course.
>
> > > Easy to see if on top of panel.
>
> > > Kirk
>
> > I think the tricky part will be calibration. *The device needs to be
> > set up to a fraction of a degree so I suspect you'll have to do some
> > fancy measuring of a series of flight tests. You'll also need some
> > data from the factory about lift coefficient versus alpha.
>
> > 9B
>
> Actually, calibration is the easy part. *Just load the glider to
> maximum gross weight, fly it at the Calibrated Air Speed (From tables
> in the POH) for best L/D, for minimum sink and for stall and note the
> readings for each. *You probably don't care about actual AoA is in
> degrees.
>
> If you want a fancy color LED display that changes color/shape
> precisely at each, the electronics package should have adjustments
> built in.
>
> Alternatively, *choose a 10 element LED bargraph display where each
> element can be red, yellow or green depending on which pins are used.
> Once the position of each AoA of interest is known, switch pins to
> produce the color desired. *You can also wire in a warning horn to
> sound when the red stall LED lights up and the gear is down.- Hide quoted text -
>
> - Show quoted text -

I think you all miss the point that a panel mounted AoA indicator is
not the right way to get this critical information. I don't want some
boob looking in the cockpit while thermaling!! That's why we create
audio variometers! I have been considering this for some time and
unless we want two channels of audio in the cockpit, or we have a very
good heads up display, the AoA info is wasted when you need it most.

Mike

[[email protected]]

I think the GLIDER is a pretty good angle of attack indicator.

[Jim Logajan]

wrote:
> I think the GLIDER is a pretty good angle of attack indicator.

Well sure - if you mean in the same sense it also makes a good terrain
alert indicator ("when the fuselage begins to deform at high speed, this is
probably an indication that terrain or an obstruction is very very close.")

[bildan]

On Jun 4, 8:32*pm, Mike Bamberg > wrote:
> On Jun 4, 11:22*am, bildan > wrote:
>
>
>
> > On Jun 4, 11:13*am, Andy > wrote:
>
> > > On Jun 4, 9:25*am, " >
> > > wrote:
>
> > > > This has all been hashed out before (some interesting threads, those!)
> > > > but here is my 2 cents:
>
> > > > AOA can be derived from pressure differential, best way would be to
> > > > have sensor ports in both wings (enough to be redundant and avoid yaw
> > > > problems. *Nose might also work, but it's the wing you care about,
> > > > really.
>
> > > > AOA is really only needed at high angles: Stall, Min Sink, L/D max,
> > > > recommended approach speed. *Since these speeds vary with weight and
> > > > bank angle, AOA is better than airspeed. *So to keep it simple, with
> > > > gear up show min sink (for thermalling) tied to flap setting, and
> > > > maybe have an index at L/D max (not really used that often). *Gear
> > > > down, show desired approach speed, with warning approaching stall.
>
> > > > I think the military chevrons and doughnut indicator would work just
> > > > fine: *On-speed (desired AOA) when center g(green) circle is lit.
> > > > Slightly slow when circle and lower up (red) chevron are both lit.
> > > > Slow when only red up chevron is lit, slightly fast when circle and
> > > > upper down (yellow) chevron is lit, and fast when only down chevron is
> > > > lit.
>
> > > > Electronics would need input from gear and flaps, if present, of
> > > > course.
>
> > > > Easy to see if on top of panel.
>
> > > > Kirk
>
> > > I think the tricky part will be calibration. *The device needs to be
> > > set up to a fraction of a degree so I suspect you'll have to do some
> > > fancy measuring of a series of flight tests. You'll also need some
> > > data from the factory about lift coefficient versus alpha.
>
> > > 9B
>
> > Actually, calibration is the easy part. *Just load the glider to
> > maximum gross weight, fly it at the Calibrated Air Speed (From tables
> > in the POH) for best L/D, for minimum sink and for stall and note the
> > readings for each. *You probably don't care about actual AoA is in
> > degrees.
>
> > If you want a fancy color LED display that changes color/shape
> > precisely at each, the electronics package should have adjustments
> > built in.
>
> > Alternatively, *choose a 10 element LED bargraph display where each
> > element can be red, yellow or green depending on which pins are used.
> > Once the position of each AoA of interest is known, switch pins to
> > produce the color desired. *You can also wire in a warning horn to
> > sound when the red stall LED lights up and the gear is down.- Hide quoted text -
>
> > - Show quoted text -
>
> I think you all miss the point that a panel mounted AoA indicator is
> not the right way to get this critical information. *I don't want some
> boob looking in the cockpit while thermaling!! *That's why we create
> audio variometers! * I have been considering this for some time and
> unless we want two channels of audio in the cockpit, or we have a very
> good heads up display, the AoA info is wasted when you need it most.
>
> Mike

You seem to assume a pilot would be fixated on the AoA display.
That's not how it's used. Find the airspeed that corresponds to the
desired AoA and hold that airspeed. The AoA won't change if you don't
change the airspeed or bank angle.

You should be able to hold airspeed, and by extension the AoA by the
sound of the glider and control forces just like you do now - except,
with an AoA indicator, you'd know you were flying exactly the right
airspeed for minimum sink.

wby0n: "I think the GLIDER is a pretty good angle of attack
indicator." This sounds suspiciously like someone is confusing pitch
attitude with AoA.

[[email protected][_2_]]

On Jun 4, 7:32*pm, Mike Bamberg > wrote:
>
> I think you all miss the point that a panel mounted AoA indicator is
> not the right way to get this critical information. *I don't want some
> boob looking in the cockpit while thermaling!! *That's why we create
> audio variometers! * I have been considering this for some time and
> unless we want two channels of audio in the cockpit, or we have a very
> good heads up display, the AoA info is wasted when you need it most.
>
> Mike

An AOA indicator, like the airspeed indicator or even the yaw string,
can easily be used by just glancing at it. Once you have established
the correct AOA, then it's easy to maintain by looking at your
glider's nose position vs the horizon - just as you do now, with that
inaccurate airspeed indicator. The whole point is that you can
quickly set the correct AOA for the bank angle and wingloading you are
flying at (without having to guess what airspeed to use based on some
chart or graph in the flight manual - quick, what is your gliders min
sink speed with 20 gallons of water in a 37 degree bank?).

What would be real nice - and might save a life in the pattern - would
be to have aural Fast/Onspeed/Slow tones that would replace the vario
tones when the spoilers an/or landing flaps are extended (assuming
that once those are out, you are no longer really concerned with
climbing!). Then you could focus all your attention outside the
cockpit on your approach, without having to glance into the cockpit to
check airspeed. That's how we used to land F-4s, and it was a really
comfortable way to fly a visual approach.

What is amusing is that pilots who have never had the opportunity to
fly an AOA-indicator equipped aircraft seem to be reluctant to accept
it's advantages and cling to their old ways, while pilots who have
used AOA gauges love them.

Kirk
66

[Bob Whelan[_3_]]

wrote:

<Sensible stuff snipped...>
> What is amusing is that pilots who have never had the opportunity to
> fly an AOA-indicator equipped aircraft seem to be reluctant to accept
> it's advantages and cling to their old ways, while pilots who have
> used AOA gauges love them.
>
Apologies for not re-titling this thread, but I've gotta second Kirk's
observation, and, generalize it to include (for example) landing flaps
and 'anything else abbie-normal.'

I haven't flown an AOA-equipped glider, but I'd sure like to. Meanwhile
since 1981 I've been flying a genyoowinely abbie-normal sailplane:
American racing glass (Strike 1!); w/o spoilers (Strike 2!!); and a
side-stick (Strike 3!!!) Oh yeah...while I'm at it, it never had a
chance at obtaining an approved (non-experimental) type certificate,
either. (You're not only out...you're outta the GAME!!!!)

Writ smilingly, with a rueful shake of the head, we pilots as a group
tend to be: a) relentlessly conservative/sheeplike in our 'common
wisdoms'; b) vocal in our (often not-factually-supported) opinions; and
c) 'too-often guilty' of passing off the latter as matters of fact.

Regards,
'Asbestos Bob' W.

[Wayne Paul]

Bob,

Well it sounds like you fly a HP-18. (How did I figure that out?)

And yes, I thought the AOA in the A-3B Skywarrior and A-6B Intruder were great instruments and would like to have one on MY w/o spoilers sailplane.

Wayne
HP-14 "6F"


"Bob Whelan" > wrote in message ...
> wrote:
>
> <Sensible stuff snipped...>
> > What is amusing is that pilots who have never had the opportunity to
>> fly an AOA-indicator equipped aircraft seem to be reluctant to accept
>> it's advantages and cling to their old ways, while pilots who have
>> used AOA gauges love them.
>>
> Apologies for not re-titling this thread, but I've gotta second Kirk's
> observation, and, generalize it to include (for example) landing flaps
> and 'anything else abbie-normal.'
>
> I haven't flown an AOA-equipped glider, but I'd sure like to. Meanwhile
> since 1981 I've been flying a genyoowinely abbie-normal sailplane:
> American racing glass (Strike 1!); w/o spoilers (Strike 2!!); and a
> side-stick (Strike 3!!!) Oh yeah...while I'm at it, it never had a
> chance at obtaining an approved (non-experimental) type certificate,
> either. (You're not only out...you're outta the GAME!!!!)
>
> Writ smilingly, with a rueful shake of the head, we pilots as a group
> tend to be: a) relentlessly conservative/sheeplike in our 'common
> wisdoms'; b) vocal in our (often not-factually-supported) opinions; and
> c) 'too-often guilty' of passing off the latter as matters of fact.
>
> Regards,
> 'Asbestos Bob' W.

[bildan]

On Jun 5, 3:46*pm, Bob Whelan > wrote:
> wrote:
>
> <Sensible stuff snipped...>
> * > What is amusing is that pilots who have never had the opportunity to> fly an AOA-indicator equipped aircraft seem to be reluctant to accept
> > it's advantages and cling to their old ways, while pilots who have
> > used AOA gauges love them.
>
> Apologies for not re-titling this thread, but I've gotta second Kirk's
> observation, and, generalize it to include (for example) landing flaps
> and 'anything else abbie-normal.'
>
> I haven't flown an AOA-equipped glider, but I'd sure like to. Meanwhile
> since 1981 I've been flying a genyoowinely abbie-normal sailplane:
> American racing glass (Strike 1!); w/o spoilers (Strike 2!!); and a
> side-stick (Strike 3!!!) Oh yeah...while I'm at it, it never had a
> chance at obtaining an approved (non-experimental) type certificate,
> either. (You're not only out...you're outta the GAME!!!!)
>
> Writ smilingly, with a rueful shake of the head, we pilots as a group
> tend to be: a) relentlessly conservative/sheeplike in our 'common
> wisdoms'; b) vocal in our (often not-factually-supported) opinions; and
> c) 'too-often guilty' of passing off the latter as matters of fact.
>
> Regards,
> 'Asbestos Bob' W.

Every book on airfoils from the venerable Abbot's "Theory of Wing
Sections" to more modern treatises on aerodynamics show graphs of an
airfoils coefficient of lift vs. angle of attack. The other graphs
have the Cl on the X-axis so everything about a wings performance goes
back to angle of attack. You won't see any airfoil section graphs
showing airspeed. Angle of attack is THE key to knowing what a wing
is doing.

Renowned books on flying from "Stick and Rudder" by Wolfgang
Langewiesche to "Fly the Wing" by James Webb hammer home precisely
that point - angle of attack is everything. Airspeed, while useful,
doesn't come close.

The situation where jets which spend 99% of their time flying fast
have found AOA indicators essential and gliders which spend up to half
their time flying near stall don't have them has always puzzled me.

[[email protected]]

On Jun 5, 5:27*pm, " >
wrote:

> What is amusing is that pilots who have never had the opportunity to
> fly an AOA-indicator equipped aircraft seem to be reluctant to accept
> it's advantages and cling to their old ways, while pilots who have
> used AOA gauges love them.
>
> Kirk
> 66

Me personally ( and I bet most of those reluctant pilots ) are NOT
reluctant to _fly_ with an AOA indicator. I am reluctant to spend
more than a small amount of money on that indicator. I also believe
that an AOA indicator is only a small increase in safety. If my
attention wanders from the airspeed, pitch attitude, stick feel and
position and other indications of low airspeed, I don't think that the
AOA indicator would be exempt from that in-attention. I do believe
that the AOA would allow more precise flying with different wing
loadings, but I don't see many times in soaring that precise AOA
control is needed.

Again, if someone had put one in my panel, I wouldn't throw it away,
but I would not spend a lot of money on it.

Todd Smith
3S

[[email protected][_2_]]

> Apologies for not re-titling this thread, but I've gotta second Kirk's
> observation, and, generalize it to include (for example) landing flaps
> and 'anything else abbie-normal.'
>
> I haven't flown an AOA-equipped glider, but I'd sure like to. Meanwhile
> since 1981 I've been flying a genyoowinely abbie-normal sailplane:
> American racing glass (Strike 1!); w/o spoilers (Strike 2!!); and a
> side-stick (Strike 3!!!) Oh yeah...while I'm at it, it never had a
> chance at obtaining an approved (non-experimental) type certificate,
> either. (You're not only out...you're outta the GAME!!!!)
>
> Writ smilingly, with a rueful shake of the head, we pilots as a group
> tend to be: a) relentlessly conservative/sheeplike in our 'common
> wisdoms'; b) vocal in our (often not-factually-supported) opinions; and
> c) 'too-often guilty' of passing off the latter as matters of fact.
>
> Regards,
> 'Asbestos Bob' W.

Bob, did you make it to the Zuni Pow Wow in Moriarty?

The Zuni is a cool looking ship - check out the great photos on the
ASA homepage at http://asa-soaring.org/ - click on the pics for full
screen & enjoy a beautiful finish to a long flight by Randy Acree in
AV8!

Kirk

[Bruce Hoult]

On Jun 6, 11:35*am, bildan > wrote:
> The situation where jets which spend 99% of their time flying fast
> have found AOA indicators essential and gliders which spend up to half
> their time flying near stall don't have them has always puzzled me.

Might that not be because those jets are total pigs when flown at
approach speed? I suspect that if they didn't have the AOA indicator
then either they would get approached way too fast or else the pilot
would be in a constant state of "we're all gonna DIE!!". And they're
going pretty fast while trying to land on small things, such as ships.

They're also landing well below min drag/sink speed, on the "back side
of the drag curve" and depending on big engines to save their bacon if
the AOA starts to get too high. If we did that in gliders then we'd
sometimes have little option but to dive into the ground in a mush
even if we closed the brakes instantly.

Unlike those jets, we in gliders fly the approach faster and with a
lower angle of attack than many other phases of flight, deliberately
sacrificing some ultimate short landing performance for a large
increase in safety.

I can see that an AOA indicator would be useful for establishing
various reference speeds at a particular weight or bank angle, and
then maintain that configuration via our traditional method of
attitude with respect to the horizon. But I don't think it's
something that we'd ever want to use as a primary reference while
flying,

The flight path of a typical glider flown at a fixed angle of attack
is a diverging phugoid. That's not very useful. Least of all on
approach.

[Wayne Paul]

There are several thing in this post to which I take exception. However, I will mention one. A carrier approach is NOT flown on the "back-side" of the power curve. They are flown at optimum L/D for the wing when the wing is in its' landing configuration.

Oh, just one more comment..... I have never know a carrier aviation who thought "we're all gonna DIE!!" when the making a carrier approach with an inoperative AOA.



"Bruce Hoult" > wrote in message ...
On Jun 6, 11:35 am, bildan > wrote:
> The situation where jets which spend 99% of their time flying fast
> have found AOA indicators essential and gliders which spend up to half
> their time flying near stall don't have them has always puzzled me.

Might that not be because those jets are total pigs when flown at
approach speed? I suspect that if they didn't have the AOA indicator
then either they would get approached way too fast or else the pilot
would be in a constant state of "we're all gonna DIE!!". And they're
going pretty fast while trying to land on small things, such as ships.

They're also landing well below min drag/sink speed, on the "back side
of the drag curve" and depending on big engines to save their bacon if
the AOA starts to get too high. If we did that in gliders then we'd
sometimes have little option but to dive into the ground in a mush
even if we closed the brakes instantly.

Unlike those jets, we in gliders fly the approach faster and with a
lower angle of attack than many other phases of flight, deliberately
sacrificing some ultimate short landing performance for a large
increase in safety.

I can see that an AOA indicator would be useful for establishing
various reference speeds at a particular weight or bank angle, and
then maintain that configuration via our traditional method of
attitude with respect to the horizon. But I don't think it's
something that we'd ever want to use as a primary reference while
flying,

The flight path of a typical glider flown at a fixed angle of attack
is a diverging phugoid. That's not very useful. Least of all on
approach.

[Bob Whelan[_3_]]

wrote:
<Multi-level snips...>

> Bob, did you make it to the Zuni Pow Wow in Moriarty?
"Roger that." (And a good time was had by all...)
- - - - - -

> The Zuni is a cool looking ship - check out the great photos on the
> ASA homepage at http://asa-soaring.org/ - click on the pics for full
> screen & enjoy a beautiful finish to a long flight by Randy Acree in
> AV8!
It took a while (um...years!) for me to get used to its abbie-normal
lines, but it's always flown beautifully.

Tnx for the link.

Regards,
Bob W.

[[email protected][_2_]]

Some good info on AOA systems for lightplanes, including theory and
installations, at:

http://www.advanced-flight-systems.com/Products/AOA/aoa.html

This system uses flush ports on the top and bottom of the wing, along
with pitot and static inputs, to measure the Cl of the wing in real
time (and derive AOA). No probes or vanes needed.

With a glider, you would have to connect the tubing when rigging - but
you could use pitot/static quick connect for that.

Too bad our market is too small - a dedicated system for gliders,
installed at the factory, would be nice - especially if integrated
with an glide computer to share processing power, etc.

There was also a totally passive Cl meter (using pellet-in-tube
technology!) that was described in detail in a old (70s?) issue of
soaring.

Kirk
66

[[email protected]]

On Jun 6, 5:21*pm, " >
wrote:
> Some good info on AOA systems for lightplanes, including theory and
> installations, at:
>
> http://www.advanced-flight-systems.com/Products/AOA/aoa.html
>
> This system uses flush ports on the top and bottom of the wing, along
> with pitot and static inputs, to measure the Cl of the wing in real
> time (and derive AOA). *No probes or vanes needed.
>
> With a glider, you would have to connect the tubing when rigging - but
> you could use pitot/static quick connect for that.
>
> Too bad our market is too small *- a dedicated system for gliders,
> installed at the factory, would be nice - especially if integrated
> with an glide computer to share processing power, etc.
>
> There was also a totally passive Cl meter (using pellet-in-tube
> technology!) that was described in detail in a old (70s?) issue of
> soaring.
>
> Kirk
> 66

I am a bit confounded by the several suggestions that AOA info in the
cockpit would be a bad thing. Frankly a little alarm for stall AOA at
each flap setting would be quite welcome for those moments on approach
where you get distracted.

I am not entirely sure I would use it for cruise, since airspeeds are
quite adequate for this purpose and no one I know flies best L/D or
even precise McCready speeds very much anymore. It might be helpful
in thermalling to get to the precise minimum sink AOA, though I do
wonder again how useful this would be since you typically want to fly
with a bit of margin above the laminar separation speed because
dipping below is quite costly in terms of the accumulated drag losses
before you get the flow re-attached. A cool thing to know for me would
be the maximum AOA for each loading and flap setting that still keeps
you consistently away from separation given gusts, unsteady
aerodynamic effects, etc. Unfortunately, that number doesn't come out
of the POH, so we are back to some form of flight testing I think - or
some sort of rule of thumb.

Even the simple calibration Bill suggests requires three data points
for each flap setting. My glider has 6 flap settings - times three
operating points each yields 18 data points - okay that's not a
ridiculous number, probably a couple of tows on a calm day.

9B

[bildan]

On Jun 6, 6:21*pm, " >
wrote:
> Some good info on AOA systems for lightplanes, including theory and
> installations, at:
>
> http://www.advanced-flight-systems.com/Products/AOA/aoa.html
>
> This system uses flush ports on the top and bottom of the wing, along
> with pitot and static inputs, to measure the Cl of the wing in real
> time (and derive AOA). *No probes or vanes needed.
>
> With a glider, you would have to connect the tubing when rigging - but
> you could use pitot/static quick connect for that.
>
> Too bad our market is too small *- a dedicated system for gliders,
> installed at the factory, would be nice - especially if integrated
> with an glide computer to share processing power, etc.
>
> There was also a totally passive Cl meter (using pellet-in-tube
> technology!) that was described in detail in a old (70s?) issue of
> soaring.
>
> Kirk
> 66

Careful reading of their installation manual suggests that it might
work with nose ports.

[bildan]

On Jun 7, 2:14*pm, bildan > wrote:
> On Jun 6, 6:21*pm, " >
> wrote:
>
>
>
> > Some good info on AOA systems for lightplanes, including theory and
> > installations, at:
>
> >http://www.advanced-flight-systems.com/Products/AOA/aoa.html
>
> > This system uses flush ports on the top and bottom of the wing, along
> > with pitot and static inputs, to measure the Cl of the wing in real
> > time (and derive AOA). *No probes or vanes needed.
>
> > With a glider, you would have to connect the tubing when rigging - but
> > you could use pitot/static quick connect for that.
>
> > Too bad our market is too small *- a dedicated system for gliders,
> > installed at the factory, would be nice - especially if integrated
> > with an glide computer to share processing power, etc.
>
> > There was also a totally passive Cl meter (using pellet-in-tube
> > technology!) that was described in detail in a old (70s?) issue of
> > soaring.
>
> > Kirk
> > 66
>
> Careful reading of their installation manual suggests that it might
> work with nose ports.

I just got an e-mail from Advanced Flight Systems indicating that one
of their units has been installed on a glider with top and bottom
nosecone ports. The glider was apparently a Sparrowhawk and the unit
works great.

Since the AFS system is available with flap position sensors and
standard LED displays, it appears to be exactly what we need.

[Andy[_9_]]

On Jun 9, 1:45*pm, bildan > wrote:
> On Jun 7, 2:14*pm, bildan > wrote:
>
>
>
> > On Jun 6, 6:21*pm, " >
> > wrote:
>
> > > Some good info on AOA systems for lightplanes, including theory and
> > > installations, at:
>
> > >http://www.advanced-flight-systems.com/Products/AOA/aoa.html
>
> > > This system uses flush ports on the top and bottom of the wing, along
> > > with pitot and static inputs, to measure the Cl of the wing in real
> > > time (and derive AOA). *No probes or vanes needed.
>
> > > With a glider, you would have to connect the tubing when rigging - but
> > > you could use pitot/static quick connect for that.
>
> > > Too bad our market is too small *- a dedicated system for gliders,
> > > installed at the factory, would be nice - especially if integrated
> > > with an glide computer to share processing power, etc.
>
> > > There was also a totally passive Cl meter (using pellet-in-tube
> > > technology!) that was described in detail in a old (70s?) issue of
> > > soaring.
>
> > > Kirk
> > > 66
>
> > Careful reading of their installation manual suggests that it might
> > work with nose ports.
>
> I just got an e-mail from Advanced Flight Systems indicating that one
> of their units has been installed on a glider with top and bottom
> nosecone ports. *The glider was apparently a Sparrowhawk and the unit
> works great.
>
> Since the AFS system is available with flap position sensors and
> standard LED displays, it appears to be exactly what we need.

Cool. They need to cost-reduce it. $890 is a bit steep for a glider
installation.

9B

[TonyV[_2_]]

Wayne Paul wrote:
> There are several thing in this post to which I take exception. However, I will mention one. A carrier approach is NOT flown on the "back-side" of the power curve.


He did NOT say power curve, he said drag curve - whatever that is.

Tony

[Mike Bamberg]

On Jun 14, 9:36*am, TonyV > wrote:
> Wayne Paul wrote:
> > There are several thing in this post to which I take exception. *However, I will *mention one. *A carrier approach is NOT flown on the "back-side" of the power curve.
>
> He did NOT say power curve, he said drag curve - whatever that is.
>
> Tony

Tony,

Not quite sure where you got your training, but the Drag/Power curve
is the curve that describes the total drag of the aircraft and the
thrust needed to counteract that drag. In all fixed-wing aircraft the
trust and drag are opposite in direction but equal in magnitude, in
most steady-state flight situations. In the case of a glider the
thrust is the forward vector of weight from the pull of gravity. The
power plane gets to add energy to the system, as long as it has fuel,
and thus can maintain a level altitude at one airspeed. The glider is
constantly trading potential energy (altitude) for thrust to overcome
drag. and so must normally constantly lose altitude. (Our great joy
comes from the fact that air rises.)

A very good site for understanding aerodymanics is: www.av8n.com/how
This is an online book by John S. Denker and is very well written. I
insist my power students read it for the very clear descriptions of
the aerodynamic forces in all aspects of flight. The first chapter is
very good at describing the "energies" of flight. If you look at
John's descriptions, especially the constant-power discussions, you
can usually apply most of it to our glider aerodynamics.

For another great website, on a very different aviation topic, I also
reccomend www.pilotpsy.com. It is the application of sports
psychology to airmanship and is very thought provoking.

Have fun.