Unusual airspeed sensor
One little known airspeed sensor used ion flow to measure airspeed. As I recollect it measured electrical ion flow transverse to airflow and a combination of devices could sense airflow in any direction.
It was invented by Ed Durbin, head of Kaiser Electronics, and I had the task of interfacing it with the AH-1T electronics. That aircraft could and probably did interface with anything and everything in the inventory and then some.
As I recollect the sensor was only developed at helicopter speeds and never saw actual airframe service. Dunno if it could be extended to higher speeds. Very useful to have the full vector, rather than just forward speed.
PDF download:
http://www.aerovelco.com/papers/Durb...ctorSensor.pdf
Patent:
http://www.docstoc.com/docs/47436556...Patent-4680962