TAKEOFF Mode

Automatic takeoff can be accomplished either as a mission control command in AUTO mode (NAV_TAKEOFF) or by directly changing into the TAKEOFF mode. See also the Automatic Takeoff topic for general setup information for automatic takeoffs.

NAV_TAKEOFF Mission Command

The takeoff mission command specifies a takeoff pitch and a target altitude. During auto-takeoff Plane will use the maximum throttle set by the TKOFF_THR_MAX parameter. The takeoff mission item is considered complete when the plane has reached the target altitude specified in the mission. The mission will then execute its normal end of mission behavior if it runs out of commands in the mission list. For Plane, this is RTL.

TAKEOFF Flight Mode

In ArduPlane 4.0 and later, Automatic Takeoff is also a mode itself. When entered, the plane will use maximum throttle as set by the TKOFF_THR_MAX parameter, climbing with TKOFF_LVL_PITCH maximum and takeoff roll limits (LEVEL_ROLL_LIMIT ) ,climbing to the TKOFF_ALT altitude and proceeding at the initial launch heading until TKOFF_DIST from the point where the mode is entered. It will then loiter, as in LOITER mode, at TKOFF_ALT altitude until the mode is changed.

Once TKOFF_LVL_ALT is reached, or the loiter point distance is reached, maximum throttle and takeoff roll limits (LEVEL_ROLL_LIMIT ) are stopped and normal navigation begins to the loiter point and altitude. Normally, TKOFF_LVL_ALT is 5-10 meters and is intended to limit navigation (roll) in order to prevent wing tip ground strikes.

If the mode is entered while already flying, it will immediately begin loitering as in LOITER mode if at or above TKOFF_ALT altitude above ground, otherwise it will climb to that altitude and then begin loitering .

TAKEOFF mode can also be entered via a switch using an RCx_OPTION = 77, as well as via normal selection by the flight mode channel.

TAKEOFF Heading

Before takeoff it is important that the plane be pointing into the wind, and be aligned with the runway (if a wheeled takeoff is used). The plane will try to hold its heading during takeoff, with the initial heading set by the direction the plane is facing when the takeoff starts. It is highly recommended that a compass be enabled and properly configured for auto takeoff, as takeoff with a GPS heading can lead to poor initial heading control such that heading can different from the initial heading by tens of degrees during the climb. While this may not be an issue for hand launches, runway takeoffs require a compass for adequate heading control during the takeoff rollout.

If you are using a wheeled aircraft then you should look at the WHEELSTEER_* PID settings for controlling ground steering. If you are hand launching or using a catapult you should look at the TKOFF_THR_MINACC and TKOFF_THR_MINSPD parameters.