Cruise, Loiter and RTL speeds different

For some reason my cruise speed is higher than expected. I am using an airspeed sensor and have tuned all the normal params. In RTL and loiter the speed is correct but in cruise it is approx 10mph higher. See attached pic. Any ideas? Thanks!

cruise speed comes from your throttle stick, min stick is min airspeed, max stick is max airspeed

Thanks. So even at mid throttle it will fly at a different speed in cruise as it does in RTL and loiter when at mid stick? So mid way between my min and max is 16.5 m/s. Is that what it is trying to attain even though I have airspeed cruise set to 12? Should I move the min and max to have 12 right in the middle? That would really throw my min too low.

Do you have THROTTLE_NUDGE turned on?

Yes and was going to test that extensively today but it ended up being too windy to fly. My throttle stick is center sprung so not sure if it will reduce speed at lower throttle but then go back to mid speed when the throttle is re-centered. Any idea? Thanks

I’ve never setup a plane with center sprung throttle. I’m not sure how that would react. Typically with throttle nudge when you go below mid travel the plane stays at it’s cruise speed (TRIM_THROTTLE). Throttle nudge only works above mid travel.

Do you have an airspeed sensor?

Yep, airspeed sensor installed. FYI this is a quadplane (Swan K1 converted to a wing 765 on ardu 4.2) I supposed I can unspring it. Really wish I could map one of my dials to trim center throttle as needed. Thanks for your help btw.

Yeah, just realized this is a VTOL so I should be careful since I don’t have experience there. But that explains the sprung throttle.

I wouldn’t recommend adjusting the trim on the radio. TRIM_THROTTLE is in the FC. For the most part with Ardupilot you never adjust the trim on a radio. That should always be at the calibrated level.

Forgot to mention, if you have an airspeed sensor you can also adjust TRIM_AIRSPEED_CM.

It flies great in fixed wing mode otherwise. I just wish I could find a way to get the cruise speed to the same as when it is in RTL or loiter. Those are perfect at center throttle.


I have read that but unless I am mis-reading, this doesn’t affect cruise mode as it isn’t seen as an “automatic throttle mode”. Seems in cruise, mid throttle is the mid point between max and min.

" In FBWB or CRUISE, the target airspeed can be directly controlled with the throttle stick position. Mid throttle will set the speed as halfway between [ARSPD_FBW_MAX] (high stick) and [ARSPD_FBW_MIN] (low stick)."

So if this is the only way to adjust mid throttle, I would need to change my max and min to setting that would just not be correct for my airframe.

I guess I can see the reasoning for this. Perhaps I will just unspring it. Would be awesome to be able to unspring automatically when in FW and spring when in quad.

On the other hand, if throttle nudge is working properly and doesn’t go back when throttle is centered, that is a solution.