hawk37
So if I was flying this aircraft manually, and it had a zero stick force gradient, then there would be no trim required as the speed was reduced from 250 to 240. But it would surely be easily controllable.
JT says
If the stick force gradient reduces towards zero, the aircraft becomes progressively more imprecise, tiring, and anxiety producing for the pilot to fly...
I can relate the description given by one TP who was caught in such a predicament during a flight test as a consequence of inadvertent gross misloading for the test point. His observations were that
(a) unless one recognised (immediately) what the problem was .. and the technique needed to control it, the outcome would be quick and inevitable. Certainly, the accident records have many examples of loss of control (with a subsequent hull loss) following significant loading excursions outside the aft CG - a commonplace initiator for an unacceptable static stability condition.
(b) flying technique involved numerous short, sharp control inputs to put the nose where it needed to be (ie stick movement remains normal) and then freezing the control position to avoid the variable loading perceptual problem.
He managed to continue this long enough to drag the aircraft around the circuit and throw it back onto the ground. His commentary suggested that it would not be desirable to have continued for much longer in such a high workload situation. If one notes that this particular TP is a very experienced trainer of TPs .. puts the observation in some sort of perspective
Apparently it's not easily controllable. In reality how many lots of 4% of trip fuel saved (it was likened to winglets earlier so I'll take that at face value, I don't know enough to say otherwise) is an aircraft hull and all those aboard worth when it all turnd turtle ? I'm all in favour of pushing things forward but a sensible balance must be maintained I'd think. Although JT's TP friend story involves negative stability, then neutral stability must be around halfway bewteen where we're at and that episode described. I'd rather keep as far away as possible from handling characteristics like those for as long as possible thanks. Just my 2c worth, more than willing to be educated if I've missed something big though.