RST Engineering - JIm wrote:
Those might get me airspeed but I'm not at all sure how you would get theta
from any one of these schemes.

Jim


Use variable capacitance, variable reluctance, resistor strip or
synchro connected to a vane. For a real giggle do as some Air Force
systems and employ a slotted, rotating cone for a probe. It involves a
feedback loop.

Dan, U.S. Air Force, retired



The vane types are self explanatory.

http://www.aircraftmech.com/pics/aoa.jpg

http://spaceagecontrol.com/4239-01image.jpg

The cone type is a bit more complicated. Picture a hollow stainless
cone with two sets of slots running between base and apex. The slots
face towards the front of the airplane. Each set opens to its own
chamber in the cone. The pressure in each chamber is measured and the
cone is rotated until the pressures are equal. The position is then
transmitted to an indicator.

http://www.avionics-specialties.com/...thumb_stat.jpg

The cone types are usually heated to prevent icing.

If I were to build one for small aircraft I'd go with a vane and
resistance strip. In that case a standard d'arsonval meter or column of
LEDs could be used to indicate AOL.

Pressure differential systems have the disadvantages of icing or dirt
contamination.

Dan, U.S. Air Force, retired