land detector: commented takeoff throttle values for each mode

src/modules/land_detector/MulticopterLandDetector.cpp

@@ -239,14 +239,21 @@ bool MulticopterLandDetector::_get_landed_state()
 
 float MulticopterLandDetector::get_takeoff_throttle()
 {
+	/* Position mode */
 	if (_control_mode.flag_control_manual_enabled && _control_mode.flag_control_position_enabled) {
+		/* Should be above 0.5 because below that we do not gain altitude and won't take off.
+		 * Also it should be quite high such that we don't accidentally take off when using
+		 * a spring loaded throttle and have a useful vertical speed to start with. */
 		return 0.75f;
 	}
 
+	/* Manual/attitude mode */
 	if (_control_mode.flag_control_manual_enabled && _control_mode.flag_control_attitude_enabled) {
+		/* Should be quite low and certainly below hover throttle because pilot controls throttle manually. */
 		return 0.15f;
 	}
 
+	/* As default for example in acro mode we do not want to stay landed. */
 	return 0.0f;
 }
 

src/modules/land_detector/MulticopterLandDetector.h

@@ -116,7 +116,7 @@ private:
 	uint64_t _min_trust_start;		///< timestamp when minimum trust was applied first
 	uint64_t _arming_time;
 
-	// get pilot throttle threshold with which we should quit landed state and take off
+	/* get control mode dependent pilot throttle threshold with which we should quit landed state and take off */
 	float get_takeoff_throttle();
 };