Hello,
I have been happily flying TBM900 without the “experimental flight model” button checked in XP. Everything seems to work as I would expect.
Somewhere here on the forum I was reading that the experimental flight model was either recommended or optional. So I turned it on and started a new flight. I even made a new airframe (I wasn’t sure if this was needed).
I did have a well documented “bumping” issue. I was bouncing up and down like a bus on a street with potholes on the runway.
in addition to that issue and more problematic, I started having more issues around 15k feet. It felt like the flaps were in T/O with the autopilot off. Like there was a lot of drag and a LOT of lift. The autopilot would not hold the attitude of the flight director. It was trying to trim, and it was commanding the control surfaces. The autopilot was unable to maintain FL270 with Torque power in the “cruise” band, even with the FD showing nose down it continued to climb at 100-150 ft/min any additional throttle just added to the pitch up with the autopilot unable to correct further. I imagine based on this there is some limit which the autopilot runs the trim out to, because I was able to trim nose down manually, disengaging the autopilot, and fly level by hand but I was almost out of trim. In the old flight model this is not a problem. In “non experimental” I am flying right now at FL270 with power in the cruise band at Mach 0.54 and the autopilot works fine
So I expect this is a regression in the experimental model or my user error. Do you developers have any idea? I am happy to go through the paces, but also maybe you could talk a little about if the experimental model is needed.
-mark