The Spirit Pro is my overall favorite FBL unit to date. I would like to get the most out of it. I want to figure out a logical approach to optimizing the tail performance. There are over 12 parameters that can directly affect the tail performance:

Mechanical parameters:
1) Tail blade design
2) Tail blade length
3) Tail gear ratio
4) Tail RPM
5) Tail slider mechanical limits (tail pitch range/rudder end-points)

Spirit parameters:
1) Rudder Gain
2) Rudder Common Gain
3) Rudder Rotation Speed
4) Rudder Delay
5) Rudder Dynamic
6) Rudder Revomix
7) Pirouette Consistency

Of course there is also optimal governor performance which directly affects rudder performance.

Assuming governor performance is optimized, what is the logical step-by-step procedure to optimize the rudder performance?

1) It seems that starting with the "default" values and a Rudder Gain of 50% will make the helicopter fly fairly well and certainly will not make the helicopter fall off the sky. Where do you go from here?

2) It looks like the first value to set is the "Rudder Delay". The Spirit Wiki has a rudder servo list with a range of values for the most popular servos. http://manual.spirit-system.com/index.php?title=Servo_list The issue here is when given a range of say "0 - 4", what difference does it make whether one uses "0" or "4" or something in between? What happens if I pick "0" instead of "4" or vice versa?

3) As I best understand it, the Rudder Gain is the next value to adjust. I believe Tomas has mentioned to increase the value as high as possible. However, it is unclear to me how high you can go on this value. I believe it is mentioned to increase this Rudder Gain until the tail starts to oscillate and then back down a few points until the oscillations disappear, but it is unclear in what maneuver to encounter the oscillations. Do I increase the Rudder Gain until I encounter oscillations during hover (pretty high value) or do I increase the Rudder Gain until I encounter oscillations in a more demanding maneuver (inverted funnel) which would yield a lower value than during hover?

4) The next value to adjust seems to be the Rudder Common Gain (the rudder gain multiplier), but it seems this value needs to be adjusted only when "Rudder Gain" is 100% and there are still no tail oscillations.

5) I believe that "Pirouette Consistency" is the next value to adjust. The default value is "160". The pop-up window on the software states it "Specifies heading hold performance" and the value is mostly between 155-180, but the range is 130-250. I believe "Piro consistency" in other FBL units maintains a uniform and consistent rudder rotation rate regardless of wind without a tail whipping phenomenon. However, does Spirit use this "Piro consistency" parameter as equivalent to rudder I-gain? Regardless, how do you go about optimizing this value? The Spirit manual states, "If the value is too high, the tail can oscillate or wag. It can also cause poor stop performance. This value should be between 150 and 180. For brushless servos it is recommended to increase value by 10-15 points." But when do you see the tail oscillate or wag? During hover? During inverted tail-in funnels? What does the recommendation to increase the value by 10-15 points for brushless servos mean? Does it mean that the high value would be 190-195 instead of 180?

6) Next up is Rudder Dynamic. The pop-up window states, "Aggressiveness of rudder response. Increase for harder rudder stop behavior. Decrease if rudder bounce-back occurs". How do you tell if rudder bounce-back is occurring because this value is too high or if it is occurring because either rudder gain and/or piro consistency is too high?

7) Rudder Revomix. My guess is that you adjust this number, if the tail is not able to keep up with the sudden demand in torque during collective pitch pumps after all other parameters are maximized?

8) What happens when after my flying skills progress and I am able to perform more aggressive maneuvers, the tail begins to oscillate during these new demanding maneuvers? Which would be the first, second, third, etc. values I would need to adjust down?

Hi,

Did you look at this? http://manual.spirit-system.com/index.php?title=Configuration

_________________
"Flying makes me happy" -- Markus Chelios

Yes. I've read the different versions of the manual several times. I've reviewed the Spirit Wiki many times. I've gone over all the pop-up windows many times over the past couple of years as I own 7 Spirit Pro units and have set up over 10 different airframes with Spirit Pro units. All my Spirit Pro helicopters are flyable; non of them are falling off the sky. I just want to optimize the tuning and perform what may be considered "advanced" tuning. It is difficult to perform this "advanced" tuning when the currently available information is oversimplified and rather incomplete. I'm looking for a more in-depth tuning guide.

Hi,

to answer your questions:

1) It is recommended to increase the Rudder Gain as high as possible, until you will hear any oscillations in a demanding maneuvers such as pitch pump. Then decrease it little bit so it is very clean.
2) For some servos you will not notice any difference when you select 0 or 4. For some difference could be noticeable in demanding maneuvers - especially Futaba BLS servos. The problem is, that servos are programmed with own regulation which, according to the manufacturer, is the best they have found. But in extreme situations behavior can be very different based on this. Usually odd behavior when value is too high is super fast oscillations in demanding maneuvers. Or sooner you might observe too smooth response - with very fast servos.
With slow servos you will rather always need Rudder Delay. This will speed up a part of the regulation which is able to mimic fast initial response.
3) in demanding maneuvers. Mostly it is not possible to achieve fast oscillations with Spirit during hovering even if gain is 2 times higher than should be as there are dampending algorithms.
4) It is only multiplier of Rudder Gain, nothing more - for extending Rudder Gain range.
5) Yes, it is similar to I-term. But I recommend to not use what is recommended for other FBL units as each one require different tuning methods. Tail can oscillate usually during too demanding maneuvers, quite agressively in a bigger angle range. In hovering the tail can start to hunt, especially during side wind. But hunting is usually caused by mechanical issues. Hunting mean always that something is not correct and rudder performance will be not optimal generally, at least with Spirit. BLS servos require higher pirouette consistency to get optimal results.
6) Rudder stopping should be good with default settings. If not, prior settings are not good. Once it is OK with default and you will increase and bounce back is occuring, it is already too high.
7) Yes - if there is no other choice to improve the performance. Usually adding Pirouette Consistency helps. But need for revomix with fast servos mean that mechanic or rest of the setup is not entirely OK.
If your mechanic is perfect and you have fast servos, it should just work all out of the box even with non optimal settings. Less perfect mean more tuning. Poor mechanic mean a lot of tuning with non ideal results.
8) Usually the problem is in the Pirouette Consistency (too high value).

It is good to always set the Gyro Gain as high as possible so that during pitch pumping tail is holding as good as possible yet with zero oscillation. At this step it is good if Pirouette Consistency is at default value or that low to see the tail is not holding well enough.
If it does not hold position, increase Pirouette Consistency until it holds, yet with no oscillation. It is correct to start at low and continue to high values. Not in other way.

If it still does not hold the problem is probably in Governor settings. Governor could hold too well or poorly. So that you can get oscillations even if the rudder does not hold well.
It is good if governor does not hold absolutely perfectly otherwise it increases demands for rudder. So between governor and rudder good compromise will lead to optimal results.

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Spirit System developer

That really helped. Thank you.