Danvel,

You mentioned in an earlier post that it is hard to keep the gyros from drifting.
How about using two electrolytic tilt sensors, for roll and pitch, like these: http://www.frederickscom.com/product..._overview.html ?
The tilt sensor could provide a gravitational reference to recalibrate the gyros every few seconds. I've seen these sensors in digital construction levels and they are very accurate.
I don't know what vibration and acceleration does to them, but they say they make specific ones for dynamic environments...
Anyway, let me know what you think about this idea.