Plane: Documented minimum throttle during transition

plane/source/docs/quadplane-transitions.rst

@@ -26,7 +26,10 @@ Transition to Fixed Wing Mode from VTOL
 .. warning:: If you do not have sufficient airspeed, an immediate stall will occur! Since MANUAL mode is often setup as a reflex driven "bail-out", some users move, or remove this mode, and substitute QSTABLIZE or QLOITER as an alternative "bail-out" for a QuadPlane. Also if the transition is made downwind, the transition time is short, and no airspeed sensor is used in non-tailsitters, a stall could occur also since insufficient airspeed has been obtained when VTOL assistance has terminated.
 
 - If you transition to any other fixed wing mode then the VTOL motors will continue to supply lift and stability until you have reached the :ref:`AIRSPEED_MIN <AIRSPEED_MIN>` airspeed (or airspeed estimate if no airspeed sensor). This phase is called "Transition airspeed wait".
-- In non-tilt rotor configurations, the forward motor(s) thrust is controlled by the throttle stick in a manner similar to whatever fixed wing mode was entered. Transitioning to FBWB/CRUISE, throttle stick controls forward thrust as in that mode, as a speed or throttle value, depending on whether or not an airspeed sensor is in use. In FBWA/STABILIZE transitions, it is directly controlled, ie low stick is zero thrust and the QuadPlane will just hover. The VTOL motors will behave similar to that in QHOVER and will try to maintain present altitude throughout the transition. During the transition, elevator input will act as climb/descent demand to the VTOL motors, roll input as roll attitude change, unless :ref:`Q_OPTIONS<Q_OPTIONS>` bit 0 is set.
+- In non-tilt rotor configurations, the forward motor(s) thrust is controlled by the throttle stick in a manner similar to whatever fixed wing mode was entered.
+ - Transitioning to FBWB/CRUISE, throttle stick controls forward thrust as in that mode, as a speed or throttle value, depending on whether or not an airspeed sensor is in use. A minimum pusher throttle value is applied during the transition. If :ref:`TKOFF_THR_MIN<TKOFF_THR_MIN>` is nonzero, then it will be the minimum throttle. If it is zero, :ref:`TRIM_THROTTLE<TRIM_THROTTLE>` will be used as the minimum throttle.
+ - In FBWA/STABILIZE transitions, the forward throttle is directly controlled, ie low stick is minimum/zero thrust and the QuadPlane will just hover, higher stick provides more forward throttle. The VTOL motors will behave similar to that in QHOVER and will try to maintain present altitude throughout the transition.
+ - During the transition, elevator input will act as climb/descent demand to the VTOL motors, roll input as roll attitude change, unless :ref:`Q_OPTIONS<Q_OPTIONS>` bit 0 is set.
 - In the case of tilt-rotors, the motors will tilt to :ref:`Q_TILT_MAX<Q_TILT_MAX>` for throttle stick positions at or above mid-stick to begin building forward airspeed for the transition. In FBWA/STABILIZE transitions, throttle stick positions below mid-stick will proportionately rotate VTOL motors back towards vertical, since that controls the forward thrust component. Transitioning to FBWB/CRUISE in any configuration, throttle stick has no effect until transition is complete. Overall thrust to the motors will behave similar to that in QHOVER and will try to maintain present altitude throughout the transition. During the transition, elevator input will act as climb/descent demand to the VTOL motors, roll input as roll attitude change, unless :ref:`Q_OPTIONS<Q_OPTIONS>` bit 0 is set.
 
 .. warning:: Unless the :ref:`Q_OPTIONS<Q_OPTIONS>` bit 0 is set, pulling back on elevator will not only pitch the nose up but also increase the VTOL motor output to assist in climbing during the transition airspeed wait phase. If bit 0 is set, only the pitch will change and altitude will not. In tilt-rotors, this can lead to delaying, or even preventing, the transition from ever completing! For tilt-rotors, do not pull back on pitch if this bit is set, until the transition is completed!