Plane: reduce QTUN log rate to 25Hz

ArduPlane/quadplane.cpp

@@ -1885,9 +1885,18 @@ void QuadPlane::motors_output(bool run_rate_controller)
     
     motors->output();
     if (motors->armed() && motors->get_spool_state() != AP_Motors::SpoolState::SHUT_DOWN) {
-        plane.logger.Write_Rate(ahrs_view, *motors, *attitude_control, *pos_control);
-        Log_Write_QControl_Tuning();
         const uint32_t now = AP_HAL::millis();
+
+        // log RATE at main loop rate
+        plane.logger.Write_Rate(ahrs_view, *motors, *attitude_control, *pos_control);
+
+        // log QTUN at 25 Hz
+        if (now - last_qtun_log_ms > 40) {
+            last_qtun_log_ms = now;
+            Log_Write_QControl_Tuning();
+        }
+
+        // log CTRL at 10 Hz
         if (now - last_ctrl_log_ms > 100) {
             last_ctrl_log_ms = now;
             attitude_control->control_monitor_log();

ArduPlane/quadplane.h

@@ -414,6 +414,9 @@ private:
     // time of last control log message
     uint32_t last_ctrl_log_ms;
 
+    // time of last QTUN log message
+    uint32_t last_qtun_log_ms;
+
     // types of tilt mechanisms
     enum {TILT_TYPE_CONTINUOUS    =0,
           TILT_TYPE_BINARY        =1,