mason.zh Posted March 31, 2023 Posted March 31, 2023 Hello guys, I was practicing CASE 1 landing with Bankler's Case 1 Recovery Trainer map, however, the FCS (especially trim) will go crazy when taking control after watching the track sometimes. This issue might also happen if I quit the game to the main menu and restart the mission. DCS MT version What I did: 1) Start the mission 2) Pick a plane 3) After landing using ESC back to the menu and click watch track 3) After a few seconds of replay or using LCtr+Z to fast-forward a bit, I would press ESC and choose to take control. 4) Trim went crazy. The behavior: 1) Stab trim became extremely nose-up (more pronounced during the turn) 2) touching the trim up or trim down button would cause stabilators to move excessively. I recorded a short video. As you can see: At 1:17, I didn't need to pull the stick and the aircraft would turn hard, I have to push some stick to counter this. At 1:36, after gear down flaps full, I didn't touch the trim but the aircraft was already somehow on speed. At: 2:06, clicking the trim up or trim button would cause stabilators to move excessively. F18C_Track_Take_Control_FCS_ISSUE.trk
Solution Tholozor Posted March 31, 2023 Solution Posted March 31, 2023 (edited) Quote At 1:17, I didn't need to pull the stick and the aircraft would turn hard, I have to push some stick to counter this. In the current flight model behavior, dropping the flaps results in a large nose-up pitch as the wing surface area changes shape when the LEFs and TEFs extend. Quote At 1:36, after gear down flaps full, I didn't touch the trim but the aircraft was already somehow on speed. Remember that the "on-speed" refers to AoA, not airspeed. "On-speed" is whatever airspeed the aircraft is at when AoA is ~8.1°, and at that time, your AoA was around that point. The aircraft doesn't care about your airspeed, only that AoA is correct for hook-to-wire contact. Quote At: 2:06, clicking the trim up or trim button would cause stabilators to move excessively. At some point near the beginning of the track, Control Stick Steering (CSS) autopilot mode was engaged ('A/P' advisory on the left DDI) and stayed on for the remainder of the replay. CSS mode adjusts the FCS logic regarding the trim switch. There's a warning in the NATOPS that not disengaging CSS for landing can result in extreme oscillations in pitch. Ensure all autopilot modes are fully disengaged with the paddle switch (de-colonizing autopilot modes such as BALT, RALT, or ATTH on the UFC will automatically enter CSS). Edited March 31, 2023 by Tholozor REAPER 51 | Tholozor VFA-136 (c.2007): https://www.digitalcombatsimulator.com/en/files/3305981/ Arleigh Burke Destroyer Pack (2020): https://www.digitalcombatsimulator.com/en/files/3313752/
mason.zh Posted March 31, 2023 Author Posted March 31, 2023 8 hours ago, Tholozor said: At some point near the beginning of the track, Control Stick Steering (CSS) autopilot mode was engaged ('A/P' advisory on the left DDI) and stayed on for the remainder of the replay. CSS mode adjusts the FCS logic regarding the trim switch. There's a warning in the NATOPS that not disengaging CSS for landing can result in extreme oscillations in pitch. Ensure all autopilot modes are fully disengaged with the paddle switch (de-colonizing autopilot modes such as BALT, RALT, or ATTH on the UFC will automatically enter CSS). Wow, thank you so much! I just tested it, without pushing the paddle switch the A/P was stuck with CSS mode, and this would happen, after pressing the paddle switch the disconnect the A/P everything went normal! I thought F18's AP disconnect behave just like A10C's, moving the stick would disconnect all modes. Thanks again!
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