ACRO_BAL_ROLL-PITCH, same parameter for two different functions?

[beska (Luca Pescante)]

Reading the wiki it seems that the parameters ACRO_BAL_ROLL and ACRO_BAL_PITCH set two different functions:

1. The aggressiveness with which returns to level when ACRO_TRAINER is engaged with a switch (similar to the Rescue function in well known FBL system);
2. The decay rate of the virtual bar.

If my understanding is correct, this two functions are different and not correlated between each other, why are they controlled by the same parameter?

[Ferrosan (Ferruccio Vicari)]

Because decay rate of virtual flybar is supposed to have effect only if ACRO_TRAINER is disabled. Mostly meant for “scale flying” style.

[beska (Luca Pescante)]

Thank you for your reply @Ferrosan, I thought the virtual flybar was also meant for acrobatic flight, even if after some tests the feeling for flying even basic 3D manoeuvres is not that great on AP.
By the way if I want the virtual flybar feeling and a certain angular speed value for the rescue function (the ACRO_TRAINER function is enabled by a switch only when the pilot has lost the helicopter orientation, so it would be disabled for the vast majority of flight time), the two functions must have the same value, because they are controlled by the same parameter.

[Ferrosan (Ferruccio Vicari)]

@beska

By the way if I want the virtual flybar feeling and a certain angular speed value for the rescue function

I would suggest using stabilize flight mode (for 3D recovery) or even loiter (for normal flying/mild acro recovery) as “rescue” in case of pilot spatial disorientation. Then you can tune the attitude and position controller for having a smooth/slow or quick/sharp response.

[beska (Luca Pescante)]

Thank you for your solution @Ferrosan, I’ve also thought about it, but the rescue function and a flight mode seems to me different use case that maybe need a different setup:

• user would like to fly in stabilize, and maybe need smooth and slow response for better flight feeling;
• user maybe want to try some 3D moves, but need the rescue functions to work as fast as possible for level the helicopter attitude.

I’ve also found this post where @ChrisOlson advice to use the Acro Trainer, that just from its name seems to suit more the purpose.

Can position hold or RTL mode be used to rescue the heli if flying in Acro mode?

Instead of switching flight modes we use the Acro Trainer function, which can be switched in or out with a function switch from normal Acro to Trainer with self-leveling. This provides a very smooth transition back to wings-level if control is lost in normal Acro, very similar to the bailout function in FBL units. Although, unlike a FBL unit it will not provide a positive rate of climb for a bailout - you have to do that manually.

Maybe I’m too meticulous here, I’ll test changing to stabilize mode and see if it would fit my need. Also, if it could be useful to other users, I could work on a more advanced rescue function, that maybe also help with some pitch input like others commercial FBL unit.

[Ferrosan (Ferruccio Vicari)]

Understood the point @beska. Honestly, If in trouble - with a well tuned heli - pull stabilize and you are out of troubles in no time. Acro trainer : tried it couple times and it’s meaningless in my opinion. Either you are learning to fly so best to use Stabilize/Loiter flight modes (again with a well tuned heli…) or you are at a more advanced level, where pure Acro is just awesome. You might want to tune IM_STAB parameters so they match the acro collective curve.

[beska (Luca Pescante)]

Well understood, thank you for the support @Ferrosan!

[Petit_Barde (Marc Bardinet)]

Hello beska,

I’m new to AP (currently revamping to AP a not used since 15 years flybarred heli) and I’m very interested in an AP acro mode with rescue which could help like others commercial FBL unit.
Have you tested the AP stabilize mode as a rescue mode while in acro ? What are your thoughts about this rescue implementation with respect to commercial FBL units ?

Thank you in advance for your input.