From 9a2b57ca824ba6036c74a89f127d0cb5fdf40011 Mon Sep 17 00:00:00 2001
From: Eurus <105340988+AkaiEurus@users.noreply.github.com>
Date: Sun, 31 May 2026 02:36:56 +0800
Subject: [PATCH] fix(fw_latlon): align airspeed load factor (#27519)

---
 .../FwLateralLongitudinalControl.cpp          | 21 ++++---------------
 .../FwLateralLongitudinalControl.hpp          |  3 +--
 2 files changed, 5 insertions(+), 19 deletions(-)

diff --git a/src/modules/fw_lateral_longitudinal_control/FwLateralLongitudinalControl.cpp b/src/modules/fw_lateral_longitudinal_control/FwLateralLongitudinalControl.cpp
index 20ca60e0bbd..6600629bc14 100644
--- a/src/modules/fw_lateral_longitudinal_control/FwLateralLongitudinalControl.cpp
+++ b/src/modules/fw_lateral_longitudinal_control/FwLateralLongitudinalControl.cpp
@@ -607,13 +607,13 @@ void FwLateralLongitudinalControl::updateAttitude() {
 		_long_control_state.pitch_rad = euler_angles.theta();
 		_yaw = euler_angles.psi();
 
-		const float load_factor_from_bank_angle = 1.0f / max(cosf(euler_angles.phi()), FLT_EPSILON);
+		_load_factor_from_bank_angle = 1.0f / max(cosf(euler_angles.phi()), FLT_EPSILON);
 
 		// Used to compensate for higher induced drag during banking
-		_tecs.set_load_factor(load_factor_from_bank_angle);
+		_tecs.set_load_factor(_load_factor_from_bank_angle);
 		// Used to give underspeed mitigation the correct minimum airspeed
 		_tecs.set_equivalent_airspeed_min(
-			_performance_model.getMinimumCalibratedAirspeed(load_factor_from_bank_angle, _flaps_setpoint)
+			_performance_model.getMinimumCalibratedAirspeed(_load_factor_from_bank_angle, _flaps_setpoint)
 		);
 	}
 }
@@ -649,7 +649,7 @@ float
 FwLateralLongitudinalControl::adapt_airspeed_setpoint(const float control_interval, float calibrated_airspeed_setpoint,
 		float calibrated_min_airspeed_guidance, float wind_speed)
 {
-	float system_min_airspeed = _performance_model.getMinimumCalibratedAirspeed(getLoadFactor(), _flaps_setpoint);
+	float system_min_airspeed = _performance_model.getMinimumCalibratedAirspeed(_load_factor_from_bank_angle, _flaps_setpoint);
 
 	const float system_max_airspeed = _performance_model.getMaximumCalibratedAirspeed();
 
@@ -853,19 +853,6 @@ void FwLateralLongitudinalControl::updateLongitudinalControlConfiguration(const
 	}
 }
 
-float FwLateralLongitudinalControl::getLoadFactor() const
-{
-	float load_factor_from_bank_angle = 1.f;
-
-	const float roll_body = Eulerf(Quatf(_att_sp.q_d)).phi();
-
-	if (PX4_ISFINITE(roll_body)) {
-		load_factor_from_bank_angle = 1.f / math::max(cosf(roll_body), FLT_EPSILON);
-	}
-
-	return load_factor_from_bank_angle;
-}
-
 extern "C" __EXPORT int fw_lat_lon_control_main(int argc, char *argv[])
 {
 	return ModuleBase::main(FwLateralLongitudinalControl::desc, argc, argv);
diff --git a/src/modules/fw_lateral_longitudinal_control/FwLateralLongitudinalControl.hpp b/src/modules/fw_lateral_longitudinal_control/FwLateralLongitudinalControl.hpp
index 9aae9387fd5..9cf728efc8a 100644
--- a/src/modules/fw_lateral_longitudinal_control/FwLateralLongitudinalControl.hpp
+++ b/src/modules/fw_lateral_longitudinal_control/FwLateralLongitudinalControl.hpp
@@ -201,6 +201,7 @@ private:
 	vehicle_attitude_setpoint_s _att_sp{};
 	bool _landed{false};
 	float _can_run_factor{0.f};
+	float _load_factor_from_bank_angle{1.f};
 	SlewRate<float> _airspeed_slew_rate_controller;
 
 	perf_counter_t _loop_perf; // loop performance counter
@@ -248,8 +249,6 @@ private:
 
 	void updateControllerConfiguration(hrt_abstime now);
 
-	float getLoadFactor() const;
-
 	/**
 	 * @brief Returns an adapted calibrated airspeed setpoint
 	 *