Seen photos of planes with brightly collard yarn tied to them to show air flow over the wings and such. Replacing the yarn with a strip of paper and using a light detector in the wing to detect when the end of the paper strip lifts off the wing might work. Bill ----- Original Message ----- From: "Zik Saleeba" To: "Microcontroller discussion list - Public." Sent: Sunday, May 14, 2006 6:26 PM Subject: [OT] Stall warning for scale aircraft > 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 > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist