On Dec 8, 10:13 am, "Bill Daniels" bildan@comcast-dot-net wrote:
"kirk.stant" wrote in message

...

On Dec 8, 4:29 am, John Galloway wrote:
Having some time in airplanes that used AOA (gauge, lights, and
variable audio cues) in preference to airspeed during low speed flight
(F-4s, in my case) I can vouch that it's a much better way to fly -
especially when the AOA is coupled with an audio signal. But in a
glider, I thing the working AOA range that we are interested in is a
lot smaller than the AOA range that low aspect ratio jets use, so in
practice it may be more difficult to implement.

Actually, I think the opposite is more likely. Gliders operate from near
stall to high speed running. Due to the far lower wing and span loading in
gliders, the minimum AOA may be less than a jet. I'd bet that the AOA range
of a glider is greater.

There are a lot of ways to display AOA data and each pilot may have a
different preference. A vertical column of different colored bright LED's
that could be 'read' (i.e. thermal with the green LED lit.) with peripheral
vision might work.

An old Pratt-Read that I used to fly had two very pleasant windsong tones
that changed pitch right at the best thermalling AOA. Of course, that was
before audio varios. Maybe a better idea is to the replace the vario audio
with bright LED lightbar display and replicate the old PR's windsong for
AOA. The LED part should be easy since most electronic varios have a + or -
5V output for a rear seat repeater.

BTW, 'pitch strings' are sensitive to yaw because they have to be mounted on
the outside of the transparent part of the canopy which puts them way above
the 'beltline' of the fuselage. Mounting them lower and further forward
would make them less sensitive to yaw but of course, you wouldn't be able to
see them.

To find the best place for a AOA vane, you could put a bunch of yarns on the
fuselage side and a video camera on the wing aimed at them. A flight test
at various AOA and yaw angles would show the location least sensitive to
yaw.

Still, I think Wayne is on the right track with pressure ports on the top
and bottom of the nose.

Bill Daniels

Everyone is talking about AoA on the fuselage. This is not the AoA of
the wing. As noted the flap position modifies the reading from the
fueslage. What we need is a AoA that is always reading the stagnation
point on the leading edge of the wing and showing that AoA. Then, I
think, the flap is comprehended in the setup.

This could be done with a set of holes, chord-wise around the LE that
feed independent pressure sensors, integrated by a micro-controller,
then displayed and/or driving an audio signal. Very similar to some
projects I've been working on and easily done with about $400 worth of
parts. Accutate, temperature compensated, pressure sensors are
expensive.

Mike