So, quick background. I'm building an autonomous 4 rotor helicopter. I'm sure you've all come across them at one point or another, but in any case, its very simple, with a rotor/motor/speed control combo at each corner in a symmetrical X shape.

My initial goal is just to get the thing to hover level (then probably to combine that with a pass-thru to an RC receiver so I can have control of it for testing, then onto more complexity).

So really, my question is do I need a gyro? I'm using a Propeller as my uC (I think it should be plenty capable), Ive got a tri-axis accelerometer already (Hitachi H48C) and more ultrasonics then I can shake a stick at, but I'm not sure whether or not I need a gyro too. I know their purpose is for rate of rotation, which is clearly very important for PID or any other inertial positioning filters and the like, but I dont see why I cant get that data out of the accelerometer.

Actually, are there any other suggestions for other sensort/electronics that I need?

Thanks,
Borgel