Chapter 6: VTOL Tilt, Multicopter, and Return-to-Launch Parameter Configuration
6. VTOL Parameters
6.1 Tilt-Mechanism Parameters
Adjust the following parameters according to the actual aircraft configuration and operating requirements.
QTILTYAW_ANGLE=10 (Vectoring angle used in multicopter mode; 10=10 degrees.) Maximum tilt-motor angle commanded by rudder input in multicopter mode. Set it so the installed propellers do not contact the airframe.
QTILTFIX_ANGLE=10 (Vectoring angle used in fixed-wing mode; 10=10 degrees. When enabled, the tilt servos participate in vector control for both aileron and elevator inputs.)
QTILTFIX_GAIN=0.6 (Fixed-wing vectoring gain: 0=disabled, 0.6=60%, 1=100%.)
QTILTMAX=70 (The tilt servo moves to this angle and waits for the required airspeed; 70=70 degrees.)
QTILTRATE_DN=25 (Angular rate for downward tilt-servo movement when transitioning from multicopter to fixed-wing mode: 25 degrees per second.)
QTILTRATE_UP=80 (Angular rate for upward tilt-servo movement when transitioning from fixed-wing to multicopter mode: 80 degrees per second.)
Transition Parameters:
QASSISTANGLE=65 Multicopter assistance starts above this attitude angle. This is a form of stall protection: the aircraft automatically switches to multicopter assistance when the angle becomes excessive.
QASSISTSPEED=9-10 Multicopter assistance starts below this airspeed. Set it to the minimum airspeed plus 1; a value of 10 is generally suitable for T-1. This is a form of stall protection: the aircraft automatically switches to multicopter assistance when airspeed becomes too low.
QTRANSITIONMS =2000 Duration of multicopter assistance after transitioning to fixed-wing mode, where 1k=1 second; also the maximum deceleration wait time when transitioning back to multicopter mode.
QTRANPIT_MAX= 5 Maximum permitted horizontal attitude variation during transition, in degrees. A lower value produces a more stable tilt transition but places greater demands on the tilt servos and motors. T-1 supports this setting.
QTRANSDECEL= 3 Deceleration rate in M/s. This prevents transition back to multicopter mode at excessive airspeed. Switching to multicopter position-hold mode at excessive aircraft speed can cause structural failure.
6.2 Multicopter Parameters
Adjust the following parameters according to the actual aircraft configuration and operating requirements.
QACCELZ =200 Vertical acceleration. The default is 250cm/s; use a lower value where possible for small aircraft.
QVELZMAX=250 Maximum vertical climb speed (cm/s).
QANGLEMAX =3500 Maximum tilt angle in multicopter mode. The default is 3000=30 degrees. A higher value may be required for a small aircraft to maintain progress into a headwind.
QLOITBRK_DELAY =1 Braking delay after transitioning from fixed-wing to tilt/multicopter flight. A very short delay causes abrupt braking, while a long delay increases the deceleration distance. Unit: seconds.
QMSPIN_MAX=1 Maximum multicopter throttle; 1=100%. A higher value is generally suitable for small aircraft with adequate power margin.
QMSPIN_MIN=0.15 Idle throttle in multicopter mode; 0.15=15%.
QVFWDGAIN=0.05 Uses the tilt servos for acceleration or resistance to strong wind in multicopter QLoiter mode. The default is 0=disabled; set 0.05 to enable.
QVFWDALT=2 Disables tilt-assisted forward thrust below this altitude. Transition to fixed-wing mode is not permitted below this altitude.
QWPSPEED_DN=150 Maximum descent rate during a mission. Unit: CM/S.
QWPSPEED_UP =200 Maximum climb rate during a mission. Unit: CM/S.
QMSLEWDNTIME=0 Limits the throttle increase rate. This is normally 0; increase it if the power response is excessively aggressive.
QMSLEWUPTIME=0 Limits the throttle decrease rate. This is normally 0; increase it if the power response is excessively aggressive.
INITIAL_MODE =17 Starts the flight controller in Qstab mode at power-on to prevent the propellers from running on the ground if fixed-wing mode was previously selected.
6.3 VTOL Return-to-Launch Parameters
Adjust the following parameters according to the actual aircraft configuration and operating requirements.
QWPSPEED_DN =150cm/s Stage-one landing speed, cm/s.
QLANDSPEED=50cm/s Stage-two landing speed, cm/s.
QLANDFINAL_ALT=3 Stage-two landing altitude. Unit: M.
QRTLALT =100 Multicopter return-to-launch altitude. Unit: M. Set this with consideration for obstacles at the current location.
QRTLMODE=2 Enable hybrid return-to-launch (=2).
ALTHOLDRTL=-1 Fixed-wing return-to-launch altitude, in M. If set to -1, the aircraft returns at its current altitude. If an altitude is specified, the aircraft gradually descends or climbs to that altitude while returning.
QRTLMODE notes: 1: When the aircraft enters the RTL_RADUS distance from the return point, RTL immediately changes to QRTL. With a value of 1, an aircraft returning at its current altitude switches immediately to multicopter return (QRTL) upon entering this radius, even if it is still very high. Entering QRTL at excessive altitude is dangerous: wind may carry the aircraft away during the multicopter descent, and the battery may be depleted before landing.
2: The aircraft returns according to ALTHOLDRTL and descends in a spiral with radius QFWLNDAPRRAD. This parameter defaults to 0; when it is 0, the following parameter is used: WPLOITERRAD (set to 50M for T-1). The aircraft spirals down to QRTLalt, then switches to QRTL for landing.
For details, see “Automatic VTOL Landing”: https://ardupilot.org/plane/docs/quadplane-auto-mode.html For additional parameter configuration requirements, consult the relevant technical documentation.