>
> I also remember reading in an R/C
> Modelling magazine (in 1974?) about someone who built a diffrential
> electrostatic field sensor with electrodes mounted on each wingtip. The
> sensors picked up the gradient of the earth's electrostatic field. If
> memory serves, the device was switched in when the plane went into an
> uncontrolled spin, and would correct it to level flight.


Yes, that was an interesting article.  The electrodes were small
radioactive sources similar to those used in smoke detectors.  The were
connected to a differential instrumentation amplifier and gave a voltage
relative to the angle.

I experimented with the idea for another application.  It was pretty
sensitive for detecting tilt, but we could not use it for our application.
From time to time you would get false readings in the wind. It seemed there
were small pockets of ionized air that would blow by causing the false signal.

- Gary


------------------------------------------------------------------------
Gary Sutcliffe,  W9XT          Unified Microsystems
ppvvpp@mixcom.com              PO Box 133 Slinger, WI 53086
http://www.qth.com/w9xt        414-644-9036