4.7:CTUN pitch logging

ArduPilot · Feb 7, 2025 · 1c09e5b · 1c09e5b
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diff --git a/images/cruise_tuning.png b/images/cruise_tuning.png
diff --git a/plane/source/docs/tuning-cruise.rst b/plane/source/docs/tuning-cruise.rst
@@ -41,9 +41,14 @@ In FBWB or CRUISE, the target airspeed can be directly controlled with the throt
 
 .. note:: The :ref:`TRIM_THROTTLE<TRIM_THROTTLE>` parameter should be adjusted to the average throttle value used at cruise speed. It optimizes the bias point for the speed control loops and is used in case of airspeed failure.
 
-While cruising, the artificial horizon in the OSD or GCS may show an average positive or negative pitch above the level indicator (ie fuselage/autopilot level). This means that the "trim level" pitch or AOA is different than what was set during the accelerometer calibration step. This can be trimmed out so that non altitude controlled modes fly at the same speed and throttle. Do this by adjusting the pitch trim, adding the desired degrees nose up or down using :ref:`PTCH_TRIM_DEG<PTCH_TRIM_DEG>`. This also optimizes the speed control loop bias point and will allow non altitude controlled modes to fly level at the same throttle and speed. 
+While cruising, the artificial horizon in the OSD or GCS may show an average positive or negative pitch above the level indicator (ie fuselage/autopilot level). This means that the "trim level" pitch or AOA is different than what was set during the accelerometer calibration step. This can be trimmed out so that non altitude controlled modes fly at the same speed and throttle. Do this by adjusting the pitch trim, adding the desired degrees nose up or down using :ref:`PTCH_TRIM_DEG<PTCH_TRIM_DEG>`. This also optimizes the speed control loop bias point and will allow non altitude controlled modes to fly level at the same throttle and speed. The image below is a log of a vehicle flying level in CRUISE mode:
 
-Using :ref:`PTCH_TRIM_DEG<PTCH_TRIM_DEG>` to adjust cruise attitude will also add an offset to the artificial horizon on a GCS or an OSD, but this can be disabled, if desired, using the :ref:`FLIGHT_OPTIONS<FLIGHT_OPTIONS>` bitmask bits 8 and/or 9, if the attitude of the autopilot in level flight is desired, rather than a leveled artificial horizon when flying level .
+.. image:: ../../../images/cruise_tuning.png
+    :target: ../_images/cruise_tuing.png
+
+Note that the altitude is constant, but at the cruising airspeed, it requires -3deg pitch to maintain level flight. Therefore, the :ref:`PTCH_TRIM_DEG<PTCH_TRIM_DEG>` should be decreased by 3 degrees. Note also, that the throttle is at 38%. The :ref:`TRIM_THROTTLE<TRIM_THROTTLE>` also should be set to this value for best performance.  
+
+Using :ref:`PTCH_TRIM_DEG<PTCH_TRIM_DEG>` to adjust cruise attitude will also add an offset to the artificial horizon on a GCS or an OSD which makes the artificial horizon reflect the trimmed pitch condition of the vehicle (ie the "level" flight target attitude is 0 degrees).But this can be disabled, if it is desired that they reflect the pitch with respect the autopilots mounting plane, using the :ref:`FLIGHT_OPTIONS<FLIGHT_OPTIONS>` bitmask bits 8 and/or 9. The displayed attitude in "level" flight will now show the amount of :ref:`PTCH_TRIM_DEG<PTCH_TRIM_DEG>` trim pitch that has been added.
 
 Without an Airspeed Sensor
 --------------------------
@@ -56,6 +61,6 @@ Without an airspeed sensor, both the pitch trim and the :ref:`TRIM_THROTTLE<TRIM
 - Position vehicle with a few degrees nose up or down during the first, Level step of accelerometer calibration to match the cruising attitude.
 - Position vehicle with a few degrees nose up and use the  ``Calibrate Level`` button on the Mission Planner page. This adjusts the AHRS_TRIM parameters. AHRS_TRIM parameters can only change the difference between the autopilot's plane and "level" by 10 degrees maximum. If more is needed, (e.g. the autopilot is mounted slightly downward), then you can use :ref:`PTCH_TRIM_DEG<PTCH_TRIM_DEG>` to alter the AOA manually.
 
-.. tip:: You can examine ATT.DesPitch in the logs when at cruise speed in FBWB or CRUISE to determine the average pitch trim required in these modes. Appropriately adjusting :ref:`PTCH_TRIM_DEG<PTCH_TRIM_DEG>` to lower this to zero when flying level in these modes.
+.. tip:: You can examine CTUN.NavPitch in the logs when at cruise speed in FBWB or CRUISE to determine the average pitch trim required in these modes. Appropriately adjusting :ref:`PTCH_TRIM_DEG<PTCH_TRIM_DEG>` to lower this to zero when flying level in these modes.
 
-.. note:: when using :ref:`PTCH_TRIM_DEG<PTCH_TRIM_DEG>` to adjust trim, it will be reflected in the ATT.Pitch log message, and also in the OSD and GCS horizon displays (ie level horizon pitch = :ref:`PTCH_TRIM_DEG<PTCH_TRIM_DEG>` + the calibrated level pitch) so that the display will be level when flying "in trim" even though the plane's pitch is different than the autopilots calibrated pitch. 
+.. note:: when using :ref:`PTCH_TRIM_DEG<PTCH_TRIM_DEG>` to adjust trim, it will be reflected in the ATT.Pitch log message, and also in the OSD and GCS horizon displays (ie level horizon pitch = :ref:`PTCH_TRIM_DEG<PTCH_TRIM_DEG>` + the calibrated level pitch) so that the display will be level when flying "in trim" even though the plane's pitch is different than the autopilots calibrated pitch with the vehicle level with respect to fuselage chore line.