Li'lJugs wrote:Then I pulled full up elevator, and the 172 shot up like it was a jet, almost. Still in whatever AP mode I was in at the time.
I had a curious set of hands pull my yoke for me during an autopilot-engaged moment and also saw this behavior, as well as significant porpoising (to the point where I thought something broke!) afterwards. I performed a divert to a nearby air field with repair facilities, assuming the worst, and found the aircraft to be in good health. Phew.
From what I can gather, the AP modeled in A2A's 172R controls pitch purely with the trim tab, so, if you yank the yoke while a pitch mode is engaged, you'll establish a new attitude from which the AP tries to recover via tweaking just the trim tab (in whatever the mechanical/electrical equivalent of a panicked frenzy is). From what I've seen of real-world GA aircraft auto pilots that use electric pitch trim, they tend to alter pitch trim at a very slow rate, thus the porpoising resulting in a phugoid oscillation, which kind of looks like an 'out of control' aircraft. I've not read the manual for the AP unit modeled, but this scenario fits my understanding of how this AP works.
I've never flown a real 172 with an AP, so, this is all conjecture from me!
Hope this helps!
-Ian C
