Message from kenkad:
you might want to consider small pneumatic cylinders operating at 125psi, cross coupled so they are not spring loaded. Small air tank (1 gallon or so) with a 12VDC compressor to maintain air supply. I use this in combination with light oil hydraulics (spring loaded air cylinder driving a hydraulic cylinder) for the disk brakes on the vehicle I had posted some time ago in the air and ground mobile thread. if you are interested, i can send you a JPG of the manifold/PCB/valving that is used for pneumatic steering on that vehicle I showed. You could do something similar for flight controls because that was what we would be doing on a joined wing version of that vehicle. All positional sensing is done with magnetic sensors as feedback to the joystick controls/control panel. You would need to send me a private email to firstname.lastname@example.org because I will not post any more of this work on the HBA forum.