Compass module instead of Gyro: anybody tried that?

[EWo_Ge]

I'm planning to use a Parallax SX chip to realise some extra functions for a heli. One of the functions is an output for the gyro.
I stumbled ovr the compass chip, which is sold by parallax and started to wonder, if this could work as an replacement for the gyro. The resolution of 11 bit should be more then enough.
The sampling time of typicaly 30ms could be also OK.

Has anybody tried it before???

Thanks for any feedback,
EWo

[jeffs555]

The problem with magnetic sensors is that they are sensitive to tilt, ie you have to know the angle of the sensors relative to the earths magnetic field. So you also need a tilt sensor(typically an accelerometer) which will cause problems because the acceleration of the plane or heli keeps changing. Here is one article about the problems with using magnetic sensors for heading determination. http://www.ssec.honeywell.com/magnetic/datasheets/lowcost.pdf

Most autonomous flying machines use a combination of magnetic sensors, accelerometers, and gyros.

PS That Parallax chip is only a two axis magnetic sensor. For airborne use you would need a 3 axis magnetic sensor.