Plane: Remove takeoff recalculation dead code

[rubenp02]

The takeoff calculation changes introduced in c15fa7b and 6ce6ef8 mean the heading no longer gets recalculated at TKOFF_LVL_ALT. Removed the related code as it never runs.

[Georacer]

Hello @rubenp02 !

Thanks for this code inspection.

So basically after 6ce6ef8, the segment

    if (plane.flight_stage == AP_FixedWing::FlightStage::TAKEOFF
        && plane.steer_state.hold_course_cd == -1 // This is the enter-once flag.
        && (altitude_cm >= (level_alt * 100.0f) || start_loc.get_distance(plane.current_loc) >= dist)
    ) {
        const float direction = start_loc.get_bearing_to(plane.current_loc) * 0.01;
        plane.next_WP_loc = start_loc;
        plane.next_WP_loc.offset_bearing(direction, dist);
        plane.next_WP_loc.alt += alt*100.0;
        plane.steer_state.hold_course_cd = wrap_360_cd(direction*100); // Necessary to allow Plane::takeoff_calc_roll() to function.
    }

never gets executed.

This means that the loiter target direction for the TAKEOFF mode is set once during the first motion of the plane on the track and is never re-set once the plane reaches TKOFF_LVL_ALT.
@Hwurzburg does it sound like this is a behaviour we want?

[rubenp02]

I think it's desirable because the main point of the heading recalc was to correct yaw errors which isn't needed with the new changes. Also, silently recalculating the heading like this caused issues. For example, planes with no rudder and some propeller induced yaw veer slightly before TKOFF_LVL_ALT as they can't roll to compensate, which meant that in this case the actual takeoff heading never matched the one reported to the GCS.

[Ryanf55]

Have you tried adding an AP_InternalError in the code block and run the entire plane autotest suite to better ensure it's never called currently?

[Hwurzburg]

@Hwurzburg does it sound like this is a behaviour we want?

sounds like it

[rubenp02]

Have you tried adding an AP_InternalError in the code block and run the entire plane autotest suite to better ensure it's never called currently?

Will do

[rubenp02]

Can confirm that it's never called in the tests