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