RogerN wrote:
/snip/
Think of the possibilities for a heading stabilize function in a
homebuilt!
A HH gyro driving a big servo, controlling a servo tab on the rudder.
Something similar could be arranged for pitch hold (a sort of super cheap
altitude hold/augment?)

Brian W

The heading hold gyros are rate gyros and use a microcontroller to integrate
the error. They hold heading real well but drift over time. Most of the
time we can trim out the drift well enough to not be a problem but remember
most model helicopter flights last no more than 15 minutes and if a constant
heading was held for an entire 5 minutes it would be a long and boring time
for the pilot. /snip/
RogerN


Good thought. Gyros drift.
When I consider my personal heading hold, cross country, I drift way
more than any gyro I could buy, I reckon :-)

Moreover (as I find to my cost) a mini rate gyro won't drive a torquey
servo, unless I beef up the output signal.
It's pretty to watch a little scrap of gyro stretching and shrinking a
1.5 millisecond pulse repeated at 50Hz when I rotate the gyro.
I needed to slap together a pretend receive signal which pulses at 1.5
ms per 20 ms with a pot to vary the pulse from 1 ms to 2 ms to provide a
command signal. That's one 556 chip and a few Rs and Cs. Next step is
a heading hold - which I should have bought initially, and some mini
servos that can use this mini rate servo.

Brian W