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Documentation Index

Fetch the complete documentation index at: https://mintlify.com/PX4/PX4-Autopilot/llms.txt

Use this file to discover all available pages before exploring further.

Fixed-wing aircraft offer far greater efficiency and range than multicopters — a well-tuned plane can cover dozens of kilometers on a single battery charge while carrying a survey camera or other payload. PX4 supports standard planes, flying wings, V-tail configurations, and more. All share a common control pipeline built around the Total Energy Control System (TECS) for integrated pitch and throttle management. This guide covers everything from wiring control surfaces to tuning for autonomous missions and selecting a launch mode.

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Supported frame types

PX4 covers all common fixed-wing geometries. Key built-in airframes:
Airframe IDNameConfiguration
2100Generic Standard PlaneAileron + elevator + rudder + throttle
3000Generic Flying WingElevons only, no separate rudder
2106Albatross UAVStandard plane with pre-tuned gains
If no specific entry matches your model, use Generic Standard Plane (2100) for conventional aircraft or Generic Flying Wing (3000) for delta-wing or blended-wing-body designs.

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Control surfaces

Ailerons are mounted on the trailing edge of each wing and deflect in opposite directions to generate roll. When the right aileron goes up, the left goes down — producing a rolling moment that banks the aircraft. In PX4’s control allocation system, the left aileron is type 1 and the right aileron is type 2, with roll torque coefficients of opposite sign.On a flying wing, there are no separate ailerons and elevators. Both surfaces act as elevons — combining roll and pitch authority in a single surface. PX4 handles this automatically when you select a flying-wing airframe.
The elevator is mounted on the horizontal stabilizer and controls pitch (nose up or nose down). In the control allocation configuration, the elevator is control surface type 3 with a pitch torque coefficient of 1.0. For V-tail aircraft, two ruddervators each contribute to both pitch and yaw — PX4 supports this with mixed control surface types for V-tail geometries.
The rudder is mounted on the vertical stabilizer and controls yaw. It is primarily used for coordinated turns rather than primary directional control. In PX4 configuration, the rudder is control surface type 4 with a yaw torque coefficient. On flying wings without a tail, yaw authority typically comes from differential drag using the ailerons rather than a dedicated rudder.
Flaps are optional surfaces on the inner wing trailing edge. Deploying flaps increases both lift and drag simultaneously, allowing the aircraft to fly slower during landing without stalling. PX4 supports flap deployment via a dedicated RC channel or through the FW_FLAPS_TO_SCL parameter. Wire flaps to additional servo outputs and map them in Vehicle Setup > Actuators.
Spoilers disrupt airflow over the wing to increase drag and reduce lift for steep descent approaches. PX4 supports spoiler surfaces via the control allocation actuator configuration. Map spoilers to a separate PWM output and assign the actuator function in the Actuators page. Spoilers are less common on small UAVs but are used on larger platforms requiring precise glide slope control.

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Airspeed sensor

An airspeed sensor is strongly recommended for all fixed-wing and VTOL aircraft. Without one, PX4 cannot detect an impending stall. The autopilot cannot distinguish between flying slowly into a strong headwind versus flying fast downwind — in autonomous missions, this can lead to loss of the vehicle.
Most airspeed sensors connect over I2C and plug directly into any Pixhawk I2C port. Common supported sensors include the MS4525DO and SDP3x series. After wiring your sensor:
  1. Set SENS_DPRES_OFF to calibrate the differential pressure offset at zero airspeed (with the pitot tube uncovered and no airflow).
  2. Set ASPD_PRIMARY to 1 to enable the first I2C airspeed sensor.
  3. Verify readings in QGroundControl > Analyze > MAVLink Inspector by looking for AIRSPEED messages. Blow gently into the pitot tube and confirm the indicated airspeed rises.
Some I2C airspeed sensors operate at 5 V logic while the Pixhawk I2C bus runs at 3.3 V. Check your sensor’s datasheet and use a level converter if required to avoid damaging the flight controller’s I2C bus.

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Setup workflow

1

Install firmware

Flash the latest stable PX4 release via QGroundControl (Q icon > Vehicle Setup > Firmware). Connect your flight controller over USB and confirm the firmware version after flashing completes.
2

Select your airframe

Go to Vehicle Setup > Airframe. Choose the Plane vehicle group and select the entry that matches your aircraft. For a custom build, use Generic Standard Plane (2100) for conventional layouts or Generic Flying Wing (3000) for delta wings. Click Apply and Restart.
3

Configure actuators

After restart, go to Vehicle Setup > Actuators. Verify control surface and motor assignments. Move each slider and confirm the correct surface deflects in the correct direction. Use the Rev checkbox to reverse any surface that deflects backwards.
4

Calibrate sensors and airspeed

Complete the full sensor calibration wizard. Then blow gently into the pitot tube and verify that airspeed increases in the Sensors tab before proceeding.
5

Set up RC and flight modes

In Vehicle Setup > Radio, calibrate your transmitter. Assign at minimum Manual, Stabilized, and Mission modes to a three-position switch so you can recover manually at any point during testing.
6

Tune TECS

Fly several manual circuits to establish a baseline. Then use the Fixed-Wing Tuning page in QGroundControl to adjust TECS parameters for your aircraft’s performance envelope. See the TECS tuning section below.
7

Test autonomous modes

Upload a simple loiter mission and verify the aircraft tracks waypoints correctly in a safe area before attempting full autonomous survey missions.

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TECS tuning

The Total Energy Control System (TECS) manages the trade-off between airspeed and altitude using a unified throttle and pitch controller. TECS treats kinetic energy (airspeed) and potential energy (altitude) as a single total energy budget, which produces smoother and more coordinated climbs, descents, and cruise than separate speed and altitude controllers. Key TECS parameters:
ParameterDescriptionTypical starting range
FW_AIRSPD_MINMinimum airspeed — set to stall speed plus a safety margin10–12 m/s
FW_AIRSPD_TRIMCruise airspeed — the speed TECS targets in level flight15–20 m/s
FW_AIRSPD_MAXMaximum airspeed — the upper limit before TECS reduces throttle25–35 m/s
FW_T_CLMB_MAXMaximum climb rate TECS will command3–6 m/s
FW_T_SINK_MINMinimum sink rate in unpowered glide1–3 m/s
FW_T_TIME_CONSTTECS time constant — lower values give faster response5–8 s
FW_T_THRO_CONSTThrottle response time constant5 s
Set FW_AIRSPD_TRIM first — it is the cruise speed around which TECS optimizes. Use the speed at which your aircraft flies level at roughly mid throttle with its typical payload.

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Launch and landing modes

PX4 supports several takeoff and landing methods for fixed-wing aircraft:
ModeDescriptionKey parameter
Hand launchPilot throws the aircraft; PX4 detects the launch impulse and advances throttle automaticallyFW_LAUN_DETCN_ON
Catapult / bungeeSimilar to hand launch but uses a higher launch acceleration thresholdFW_LAUN_ACC_THLD
Runway takeoffPX4 controls throttle and tracks the runway centerline during ground roll before rotationRWTO_EN
Autonomous landingPX4 flies a glide slope to a flare point, then pitches up to reduce sink rate before touchdownFW_LND_FLALT
For autonomous landings, configure the approach altitude and flare parameters in the Mission settings within QGroundControl’s Plan view.
A downward-facing distance sensor (rangefinder) significantly improves flare timing for autonomous landings by giving PX4 accurate height-above-ground data in the final meters of descent, producing smoother touchdowns.

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