Coaxial Helicopter: mixer question

Dear all,
I am in possession of a particular aerial vehicule.
It is a coaxial helicopter of the size of a class 500. It uses 6 servos (3 per CCPM swashplate) with specific angles (not 120°). It has also 2 eletrical motors.

I would like to know if it is possible to configure the mixer with this configuration, because I would like to switch to the Piwhawk FC for better integration and capabilities.

I tried a CC3D FC and it works when using the mixer table (not helicopter predefined parameters) in the settings.

Thank you in advance for your help.


There is not currently any Coaxial helicopter code in Arducopter, and no user-programmable mixer functions. So you won’t be able to use Arducopter as it is now.

However, I am actually working on a coaxial helicopter right now, and might be able to help you out if you are interested in trying some “beta” type code.

I have flown the Sovereign CTX5-FBL coaxial helicopter using just standard helicopter code. But that won’t work in your case.

I’m also working on a small type coaxial helicopter, using dual motor drive for yaw control, and 3 swash servos only. I could probably create something for your helicopter if you want to give me more details about it. With 6 servos, you could do yaw control with differential collective. But you also mention two motors, so you could control yaw with motor torque. Which do you want to use? Can you show a photo of the machine? 6 servo coaxials are actually very rare. Well, I’ve never seen one at all.

Dear Rob,
Thank you very much for your feedback. :slight_smile:

I don’t have it with me this weekend but I will try to provide you a picture. It look like that: … 3db0cc0ecd

And you understood well: Currently I am using the differential pitch on each swashplate to create yaw effect.
But maybe later it would be interesting to combine engine tork and swashplate differential. I will try that later.

To give you an idea, I was using this table with different values:
Do you think it is difficult to edit the code source to change the “weight” of each input/output? Do you know in which file should I look for that?
I have a developper friend who can help me editing the code and building from sources.

Thank you