Tail: Gain vs. Proportional vs. Integral

I understand I can adjust the tail main Gain as well as the Proportional gain and the Integral gain components. Is there a systematic way to optimize these 3 tail gain values?

Hi,

our tail control loop is designed to work mainly with the overall gain.
The values inside (Pro parameters) are empiric values which have proven themselves to be good for almost all trainer helicopters, so basically there is no need to deep-dive here.
Plus, the tail control loop is adaptive, means, it‘s gain will fade in and out, depending on the flight situation (even more so if the governor is used, if the VBar knows the load situation).

Otherwise, the same rules apply as in all tail gyros:
I-gain (heading hold gain), slowest component, can be adjusted if piro consistency or heading hold do not meet your or the model‘s requirements.
With a slow wag, or inconsistent pirouetting, particularly on large/heavy/inert models (scale ships, fenestron tails), lower I.
Usually, there is no need to increase I _if_ the tail is already holding in all situations. Too high will make the tail feel more sluggish, I is dampening pretty much.
Fly I-only, and you technically move the course marker on the compass rose, and the VBar will dial in the new direction. Not very lively.
Too high, you will get a slow but authoritative wag, too low, and the tail will eventually blow out earlier.
Limiting factor: tail rotor authority.

P-gain (proportional component), much faster component, can be adjusted to dampen I-gain (increase I over P), also to deal with tail wags.
This will also increase the crispness, to a degree where you get a fast tail wag.
The ratio between P and I makes the difference, so basically, if you lower I, you could instead try and increase P, or adjust P to best meet the new I value.
Fly P-only, and it‘s like in normal mode.
Limiting factor: tail rotor authority and also the servo.

D-gain (fastest component), can be adjusted to dampen P-gain, also to make the tail crisper. But usually, there‘s only a narrow range of values until you get a dangerously quick wag, which could quickly lead to damage or destruction of the tail rotor.

Mind that the overall gain is acting like a factor/multiplicator, to the values inside the equation. So at a higher overall gain, you get similar results with lower P/I/D gains, and vice versa, to be able to increase the overall gain, you could lower the values inside.
Within a sensible range of values, the result will be similar, so it makes not much sense to dial and tweak, to be able to see higher values in overall gain, for example. They are just numbers.

The ratios inside (Pro parameters) are dialed in and adjusted with relation to each other by default, so usually, you would only adjust the limits (in setup), gains are pre-set for the model size you chose initially. Then, you would do a trim flight (to find the sweet spot, center where the gyro does hardly have to correct, as setting up mechanically in normal mode, on vintage gyros), do an optimizer flight (to help adjusting the stop behavior, for both directions), and if necessary adjust stop gains.

I‘m content when the tail does what I want it to do, in all situations, and if it does not blow out (unless I exceed the limiting factors, e.g. a pirouette or flying backward f*ing fast, with an offset, will eventually cause a blowout).

When you are into optimizing, feel free to try, though. Just always leave a safe bank to switch back to, when things get ugly

Kind regards

Eddi

Born to fly ...
forced to work.