Tyro said
The side-stick has artificial spring feel which returns the SS to neutral.
The spring force increases with increasing displacement.
- how is that different to a conventional yoke fitted with artificial feel and hydraulically operated control surfaces? I am not a test pilot but it sounds very similar to me...
There is no artificial spring feel in the Airbus, that I know of. Of course there is feel: that of the spring, and totally unrelated to any aerodynamic variable. In normal law, there is a relationship between load factor and the angle and spring force. That's why it is very natural to fly in normal law. But in direct law, there is absolutely no relation with anything, be it speed, load factor, or whatever. Depending on the circumstances, the same spring force will have very different effects.
Artificial feeling in hydraulically operated airplanes is dependent on speed, one way or another, linearly or square of speed. It does not resemble the feeling of a directly mechanically linked FCS exactly, but enough for a pilot to instinctively feel if they are making too hard an input, and how the airplane should respond to a given input. You don't have that on a sidestick when in direct law.
The B777 went to greater lengths of complexity to achieve a pilot instinctive FCS, being it fully computerized. It is difficult to get the advantages of fbw and still make it feel like a conventional airplane that is very easy to fly. When the B777 reverts to direct law I believe it still retains artificial feeling and then it feels like a conventional airplane, only not so easy to fly, where you can trim stick forces.