Can I make RTL go faster based on ground speed or stick mix?

ArduPlane Plane 3.4
1

I have
THR_MAX 80
TRIM_THROTTLE 30 (don’t need to waste power to loiter or just cruise around)
ARSPD_FBW_MIN 14
STICK_MIXING 1

My problem is if I’m downwind, I want RTL to apply more power to come back when ground speed is very low.
Right now, I believe RTL will just apply TRIM_THROTTLE and raise the throttle if needed to reach ARSPD_FBW_MIN.
However, if it’s doing 5kts ground speed, I’d like it to increase throttle to make more headway against the headwind.

Is there any way to do this? Does stick mixing allow me to put full throttle while in RTL and have that tell RTL to go faster if it can’t figure it out on its own?

Thanks, Marc

2

Yes stick mixing will allow you to raise the throttle manually in RTL.
Thanks, Grant.

3

Thanks grant, I appreciate it.

4

More generally, though, if you’re not there to help the AP make better decisions, would it make sense to have a way to tell AP to keep a minimum ground speed in RTL?
RTL is often when things are not so good (time to turn back for battery, video lost, transmitter unreachable).

At that point, AP is in charge to bring the aircraft back. If it’s configured to fly with an airspeed of 30kph and there is a 30kph headwind on the way back, in my experience, it will not add power, and mostly fly in place until the batteries die and the aircraft crashes.

This is not quite desirable obviously :wink:
Is that tunable as is, or should I file an RFE to add support for this?

5

That’s an excellent idea to have a min ground speed for RTL.

.

6

First, after a flight this afternoon, I can confirm that RTL goes faster if I give more throttle, good.

But if I have no RC control, then I could be out of luck.

So, I just filed this RFE: github.com/diydrones/ardupilot/issues/3354

7

Well, actually it’s more complicated.
There is already MIN_GNDSPD_CM which does the work.

I assumed that it would also force CRUISE to go to that minimum ground speed, which is not what I’d want, but I may be wrong about this, the description is a bit terse and maybe it only applies to AUTO and RTL, but not FBWA and CRUISE.
If so, then I’m already all good.

8

The MIN_GNDSPD_CM also applies to Cruise, I test it.
So you are right, if I need to fly around at low speed with Cruise mode and use min throttle the lowest that I can go is the min ground speed allowed by MIn_Gndspd_Cm.
I also think that RTL should have a dedicated setting for speed and it will make more sense in case of something goes wrong.

Enviado do meu iPhone usando o Tapatalk

9

I don’t known if that’s a case because I still don’t have an idea, I have that problem in the returning flight as you can see in this post viewtopic.php?t=12717

Enviado do meu iPhone usando o Tapatalk

10

Thanks for confirming, Lbarreiro[quote=“Lbarreiro”]The MIN_GNDSPD_CM also applies to Cruise, I test it.
So you are right, if I need to fly around at low speed with Cruise mode and use min throttle the lowest that I can go is the min ground speed allowed by MIn_Gndspd_Cm.
I also think that RTL should have a dedicated setting for speed and it will make more sense in case of something goes wrong. [/quote]

Thanks for confirming Lbarreiro github.com/diydrones/ardupilot/issues/3354 has also now been re-opened.