I'm making an autonomous navigation device for an electric powered
glider. This is the kind of plane which is normally used with radio
control - it's hand-launched and has a 2m wingspan. In my "robot
plane" application the plane will be controlled by some PICs and a
gumstix SBC. It has accelerometers, gyros, GPS etc. to help it stay on
track.

One thing I haven't catered for yet is air speed. I'd like it to be
smart enough to stay out of trouble yet having no concept of wind
speed it could easily get into a stall without knowing until it was
too late.

I was wondering if anyone had any ideas for either stall indicators or
wind speed / direction indicators which would be suitable for a plane
of this size? That means small and light - it has to be able to be
carried by the plane along with the rest of the gear I'm putting in
there.

My only idea so far is to mount a resistor/thermistor combo above the
leading edge of the wing. The idea is that the heat of the resistor is
normally drawn away by the air moving over the wing but if the angle
of attack gets too great the airflow slows and the thermistor starts
getting hotter. A second thermistor would probably be required for
reference. I'm not entirely happy with this solution since power is a
consideration and I don't like burning it off in a resistor. And I'm
not sure it'd work.

Does anyone have any better ideas?

Cheers,
Zik

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