would an AOA indicator be helpful in a glider?

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

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?...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!!

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

-Paul

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

-Paul

oops.. he http://www.safeflight.com/imgs/photo...eet%20Hort.pdf

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.

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

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

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.

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

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