As far as I can see, there is no option to set the bias/balance between rudder and elevator in a vtail ruddervator config?
As an example, I would like to have greater deflection for elevator input than rudder - it appears to be pinned at 50/50 servo output.
I have looked at mixing_gain and mixing_offset but neither of these achieve the desired result. In theory it would be possible if mixing_gain could be set at <0.5, but it cannot. Setting a negative mixing_offset does increase elevator authority, but does not reduce rudder, so you end up with saturation.
It is entirely possible I am missing something, so asking the question in the hope someone can correct me. Of course it could be mixed in radio - but I don’t like doing that.
Strictly speaking saturation is not necessarily a problem, it just means that you don’t get as much authority on one axis when the other is at the extreme. Many people aren’t doing precision aerobatics and therefore a little bit of saturation doesn’t cause any problems.
It’s been a while since I set up a v-tail, but I think MIXING_OFFSET will do what you want. I tend to run MIXING_GAIN closer to 1 on my V-tails, but there’s a lot of variables there so you’ll have to try it. I’d just ground test the MIXING_OFFSET at -500 then +500 and see if that gives you what you want.
As for the value ranges, if you’re using Mission Planner you can set any value you want. You might get a warning that you’re outside the normal limits, but it will still let you make any mistake you want. If you want to test the gain at 0.4 or whatever you can do that. Note that QGC won’t let you do that.
…this is an excellent point! I was sitting there looking at the min val and thinking “if only I could set it lower” - completely forgot I can!
Still, I find it a bit odd that there is not a simple bias param - I wouldn’t have thought it was too unusual for a vtail to need more deflection in one axis to achieve the needed authority.
Thanks though - I will reduce the gain and then I set the offset as needed.
If you want to test the gain at 0.4 or whatever you can do that. Note that QGC won’t let you do that.