Diagnose Ardupilot Fixed-Wing Take off Issue

@batuhanakkova

Hi, As an Astronautical Engineer specializing in Flight Mechanics, GNC (Guidance, Navigation, and Control), and deterministic flight software, I am prepared to analyze your logs and debug your V-tail pitch behavior immediately. ​Why I Can Solve This Immediately ​- V-tail configurations require precise mixing of pitch and yaw commands. I will analyze your log to determine if the issue stems from V-tail mixer saturation, incorrect center of gravity (CoG) offsets, or PID oscillation during the throttle ramp-up phase. ​ - The "fixed altitude" stall you described suggests a potential issue with the TECS (Total Energy Control System) or the pitch-to-throttle scaling. I will examine the transition between the "Launch" state and the "Climb" state to ensure a constant 10° to 15° pitch-up. ​Immediate Action Plan ​- I will verify the "Takeoff Pitch" and "Acceleration Min" parameters to see if the autopilot is waiting for a specific airspeed threshold that is set too high for your airframe. ​- I will check for any "Dead-zone" or delay in the V-tail elevator response during the jerk-to-launch sequence. ​- Within hours of reviewing the log, I will provide a refined set of parameters for your pitch PIDs and takeoff climb-out angles. Best regards, Batuhan Akkova

@midoelgamal

Hello dear I reviewed your log and I understand the issue. The flat run is caused by the level altitude setting, and the sudden pitch-up happens because no rotation speed is defined, leading to an abrupt transition. I can help you achieve a smooth 10–15° takeoff and tune it quickly through flight testing. Available to start immediately. WBR