You could be on to something with the small gyro- I cant believe I
didnt
think of it. My model helicopter has a single axis gyro for yaw. My
first
one was a real spinning gyro, the second iteration is a little more
sophisticated. It uses a fiber optic cable wrapped around a tube
oriented
in the direction of the axis. The chip reads the "red shift" of the
light
frequency to know when the helo is rotating around its rotor.

There should be no reason this $100 component cant be used (or 3 of
them)
in an A/C to provide real time gyroscopic input to the control or
monitoring unit. The unit on my toy helo uses a simple 3 prong plug-
7.2
volt +, 7.2 volt - and a signal out. The signal out increases or
decreases
in voltage depending on which way I forgot to add rudder when I am
flying.

Kevin Alderman

Got any references for that fiber optic cable wrapped around a tube?
I am ignorant of that device.

Paul Lamar

I've never heard of this application either, it seems too fantastic to
be true, but if it does indeed work I find it difficult to believe that
it would have the ability to detect and integrate slow motion.
Detecting yaw of a toy helicopter being monitored/corrected for
rotations < 10 secs/rev is one thing, but aren't we talking about an
aircraft application where we want to be able to integrate rotational
displacement over a period of minutes rather than seconds?
Light travels at a speed of about a nanosecond/foot so we are really
talking about some sophisticated measurements here.  Maybe they are
wrapping two fiberoptic cables around a tube, one clockwise, the other
counterclockwise, then producing an interference signal that would be
much easier to measure.  Fascinating indeed!

I guess it all comes down to the accuracy/precision of the optical
sensor.  I was impressed 40 years ago when I spent some time in the
cockpit of a Finn Air 707 charter between Minnesota and Finland.
Somewhere over Greenland the Captain pointed out the inertial-guidance
unit that was sitting there clicking off changes in longitude/latitude.
He said that it was accurately calculating micromovements of the
aircraft and integrating them so precisely that he could find the
Helsinki airport within a mile or two after a trip of 4000 miles and an
8 hr flight.  That's good enough for me.

I will be looking for more information on these optical gyros.

R

Look up ring laser gyro's. Widely used until GPS.

Paul Lamar