ShadowFrost Posted June 12, 2022 Posted June 12, 2022 (edited) The aircraft FBW does not protect from a departure with relatively harsh rudder input. Likewise, this could be correct as is as I am close to the (or slightly past) the acceptable limits. Just reporting plausibly suspicious behavior. Did not exist in previous builds but is also very difficult to recreate. If ED has additional tools from the track file they can determine whether it is pilot stupidity (FLCS overload) or another issue at play. Edit- It should be noted that the last (known) pilot input was in the vertical before the spins. Everything after the initial rudder command was more or less uncontrolled/commanded and unrecoverable due to altitude. More info. 8.5G pull 15-16 units of AOA before departure from controlled flight. https://streamable.com/rhoxzp Stability.trk Edited June 12, 2022 by ShadowFrost Grammar/More Info
DummyCatz Posted June 12, 2022 Posted June 12, 2022 (edited) I'm trying to analyse what happened in this departure. Initially there's a rapid overshooting of AOA limit due to the inertia coupling maneuver, which I described in another post. The inertia coupling phenomena is real so it may not be a bug that caused an overshoot. The FLCS do have some protections against inertia coupling so it depends on the implementation of both FLCS and aerodynamics. After the aircraft departed from controlled flight, the rudder is not trying to counter yaw rate, but to enhance it. That's why you can see all kinds of yaw motions happened there. (See the yaw rate limiter bug below) Then there's a bit of random pitch up and down due to the relaxed static stability characteristics of the aircraft. There's a chance of throwing the aircraft into a deep stall trim point and stuck there, which is around +/- 60 deg AOA, in both positive and negative AOA region, due to the stalling/overshadowing of the horizontal stab. You can check the pitching moment coefficient curve in this blog for better understanding: https://web.archive.org/web/20090627050146/http://www.codeonemagazine.com/archives/1986/articles/july_86/deep_stalls/index.html In the last bit of the departure motion, something weird happened when the aircraft suddenly backflips from positive AOA to negative AOA, which led me into issuing a bug report: By looking closely at the horizontal stab position in relation to the pitch rate of the aircraft, it is exactly the horizontal stab that drives the aircraft into the negative AOA. It deflects trailing edge down even when the pitch rate is negative (pitch-down motion). Both issues are reported. Hope it helps. Edited June 14, 2022 by DummyCatz 1
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