This is a bit like the flutter debates. How do you recover if you encounter flutter? Well, to start with, just don't go there. If you do end up there, there may be one or two things you can try, but none are guaranteed.jimdavis wrote: ↑Sun Nov 19, 2023 9:12 am Thanks, Peregrine. Well whether it's called the "neutral point" or "stick neutral point" it't not a good place to be.
So can anyone (Stressors) tell me what I must have done to live through that? Changed the airspeed? flap setting? or power? Because something made it less unflyable.
I've never flown an aircraft with a CG back far enough to cause real stability problems. Peregrine and some others may have flown the variable stability demonstrator during flight test course, but I'm not sure how close they took the demonstrator to true neutral stability.
I did once see an aircraft airborne with a CG too far aft. It was a new prototype on an early program flight, as part of the envelope expansion. The problem was immediately obvious from the ground, manifesting as a very uneven flight path. The pilot was obviously struggling to keep the aircraft on the desired flight path, the 1 hour sortie was converted into a single circuit. Amongst the lessons learned is not to contract out the stability analysis to the lowest bidder. From the in-cockpit footage the pilot was obviously having to apply constant corrections to the pitch control, but to his credit both he and the flight test engineer handled it really calmly and professionally.
What could you do? Well, reducing power as much as possible may help. In general, for single tractor propeller engines, power reduces longitudinal stability. I emphasise the "in general", as it does depend on the aircraft configuration. The effect of power is to change the slipstream over the tailplane, and depending on the engine thrust line it could also change the pitching moment.
Coming back to the original question from Chalkie, I am still intrigued by the DFE discussion. Seems everyone here is in agreement with Chalkie, yet the majority at the DFE meeting seemed to disagree. Are we missing something?