AP pitch jolt when approaching target altitude
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I noticed that when some 700ft of target altitude, right when AP transitions from ATT to ALT mode, there is a jolt in pitch, the plane pitches to almost level and then to previous pitch again, to reach the target altitude. The jolt can be either up or down, seemingly random.
Using Grand Duke and KLN90B + KX panel combo.
Is the description enough to reproduce, or a video is preferred? -
I see that on my end too. Thanks for the detailed description. From interrogating variables, it's caused by "outer loop's" commands to the flight director, not the "inner loop", which is the autopilot's PID controller. From my work on the Starship, I've seen that the outer loop has some... interesting behavior when it comes to flight director commands during mode changes. I'll experiment with this a little and see if there is something I can do. That being said, the Duke owner who had a Century IV in his airplane told me that he actually warns passengers before changing autopilot modes because the "bump" can be significant when it commands pitch changes.
