John Tulla said:
one of the first skills that is lost is what is known as "fine motor control," especially in the hands
gums has made some comments on the F16 stick. I recall from a course years ago (so it might be scratchy) that the initial test article had a zero break out stick arrangement which was unflyable due to low level muscular tremors. If I recall correctly, the initial mod was to introduce a 4lb break out load to get rid of the non-commanded small perturbations.
My memory of the F-16 development (not hands on) is rather hazy as well. But, I seem to remember that the change to the initial fixed-stick force-control only was to incorporate a 1/16 inch backlash movement and include a breakout force measured in mere ounces...just enough feedback to let the pilot know that he had made a control input. Any more would have caused major problems in formation flying and sight corrections during weapons delivery.
I can't remember the stickforce per g for the F-16 (but I am sure someone will jump in). However, the force used in typical fighters at the time such as the F-18, was one lbf per additional g (with also one inch aft stick movement for the F-18) in pitch. The F-18 break-out force was very low.
With regards the Airbus series with sidestick control I seem to remember a 3 lbf breakout force being required to cause the AP to disengage if the instinctive disengage button was not used. The breakout force in manual flight is tiny but noticeable without being objectionable.
Again with regards the Airbus series, in normal flight, the fore and aft movement of the stick in pitch is a g command system (not pitch angle or rate)...ie, back stick commanded an increase in g above 1.0g and vice versa for a forward stick command.
If impending overspeed was sensed, the flight controls would automatically pitch the aircraft up at up the +1g additional (to reduce pitch angle and speed) but stayed in the g command mode.
On the other hand, if impending stall was sensed, the flight controls would go into the alpha mode where fore and aft stick controlled AOA (not g) until such time that the actual AOA reduced below a set value.
These control modes described rely on air data from the ADRs. Any wrong data from the ADRs is quickly detected but, in the meantime the erroneous data can cause the flight controls to revert to degraded flight modes and trip FCS computers off line.
I think that one of the most insidious effects of the degraded modes is when the THS "freezes". In this case the THS
MUST be controlled manually using the pitch trim wheel.
I have seen many students completely caught off guard in the simulator when this happens as they try to control the aircraft in pitch using sidestick alone. Of course the THS completely overpowers the sidestick which is only controlling the elevators in this case.
There is an appropriate warning, but in the excitement this seems to be easily overlooked. Manually reset the THS to zero trim and all is OK.
Simulator training is essential to instill the importance of manual THS control and should be conducted regularly during "Jet Upset" sessions.