Q_WP_SPEED_UP parameter (QuadPlane)

ArduPlane VTOL Plane
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Hello everyone.
I wanted to understand the parameter Q_WP_SPEED_UP (or Q_WP_SPEED_DN). The documentation defines this as “Waypoint Climb Speed Target: Defines the speed in cm/s which the aircraft will attempt to maintain while climbing during a WP mission.”
Naturally, I thought that the vertical velocity of the aircraft would be defined by this. That is, if the next waypoint is at an altitude greater than the current flight level, and also is very far away, I thought the aircraft would fly with Q_WP_SPEED_UP until the next WP height (not the WP itself) is achieved and then fly level to the waypoint. However, this was not the case. The aircraft did a “straight-line flight” to the waypoint (i.e. nose pointing towards the WP at all times, a slow and constant climb).
This made me think that maybe Q_WP_SPEED_UP defines the maximum vertical speed during WP missions. So I made a mission where two WP were 50 meters apart in the x-y plane, and the height difference was 150 meters. After reaching first WP, the aircraft started to climb at velocities almost 2 times the Q_WP_SPEED_UP. So, my assumption was wrong again.
Q_WP_SPEED_UP is neither the minimum, nor the maximum, and not something the aircraft maintains at all times in a WP mission.
So if someone could explain this parameter to me, that would be great.

I did these mission tests in Mission Planner SITL. The flight was in FW mode. One more thing could be that this parameter only defines the Quad part of the QuadPlane. I don’t know.

Anyway, thanks in advance!

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You’re correct here, and what you have observed in flight is the expected behaviour when navigating between waypoints in fixed wing modes.
The Q_WP_SPEED_UP has no effect during navigation in fixed wing flight modes, only in modes where the VTOL motors are being used.

All parameters starting with “Q_” affect only the multirotor/VTOL modes. The prefix is there to distinguish these parameters from the fixed wing parameters. If you search your parameter list with only “Q_” you’ll see all these params. You’ll notice that the rest of the name is the same as found in the Copter firmware. The documentation might not explicitly mention it since it’s coming directly from the Copter documentation, but it is generally understood because the parameter is prefixed with a “Q_”

For fixed wing modes, climb rate will depend on the max pitch angle and max throttle settings. The TECS (Total Energy Control System) will then control the climb rate requested between the waypoints. The docs for the TECS is here.

Hope this helps, cheers!

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This helps a lot! Thanks for the explanation. :slight_smile:

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