Working as a BYU electronics shop tech, I occasionally get to help out the guys at the MAGICC lab. A PhD student came in a few weeks ago with a problem: He wanted to make an Alpha-Beta probe. Encoders of the accuracy he wanted are too heavy and too expensive to put on a 5 pound flying wing, and the multiple Pitot-tube option was not his game to play either, so he was wondering if we could make encoders like the big expensive ones he was looking at, except for being big and expensive.
I got to thinking about P-factor in flying tail-draggers and high AoA flight: Props that are presented with a relative wind that is off-normal to the plane of rotation produce asymmetric thrust. Using that principle in reverse, small pager motors could be mounted to a Pitot-probe, each offset by 90-degrees. It is possible to work up different configurations, redundant placements of similarly oriented pager motor "generators" and the like, but the basic idea is that as long as the props on the pager motors are uni-directional (no camber/bias for rotation in forward verses reverse), and as long as the props are kept out of dirty air or asymmetric dynamics due to the Pitot-probe, these should make a simple Alpha-Beta measurement system.
As to taking the measurement: My hunch is that the ratio between the potential differences made by the motors resolves the alpha and beta components of the airflow. That or the current generated when a load is place accross the terminals of the pager motors.
So has this been tried before? What are some issues?