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Old 01-03-2013, 01:17 AM   #4 (permalink)
Dr. M
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Default Advanced Cyclic Tuning

In all my experimenting and reading I've not found any value in tuning cyclic roll and nick any differently on these units, so I'll discuss them both at the same time.

I think it's easier to have the tail figured out first, and endeavor into tuning the cyclic feel last. If you followed this tuning guide so far your gains should be pretty well tuned already and the tail should be very well behaved. You could very well stop with the fiddling and just go fly. In fact, I recommend you do just that: fly your newly tuned heli for 10 or so packs just to get used to the feel of these units, then go ahead and proceed to tune the cyclic to be closer to your ideal feel.

The purpose of this section is to help you get the best feel out of the cyclic controls and compensation that these gyros are capable of delivering. As before, do the tuning using the highest HS you plan to fly.

Let's start with the easy parameters:
Acceleration: When this value is high the swashplate will tilt fast when stick is moved. The default is 125 in all default configurations, and I've never found a need to change it.
Deceleration: just like the tail, this parameter control stopping behavior when a stick input is suddenly released. The effects are not quite as dramatic as the tail though, but decreasing this will make the stops softer, while increasing it will make the more crisp. The defaults are pretty good starting points; tune up or down to get the feel you're after.
Agility: this is the maximum roll/pitch rate. Adjust to taste.

The hardest parameters to tune are the PID gains. These will have dramatic effects on performance and feel. The general guidelines are as follows:

P-gain has a the largest impact on stick response; increasing it makes the cyclic feel more connected and responsive, particularly around center. You can't go too high though, increase 2-3 points at a time. Decreasing P-gain will soften the cyclic response, making in more robotic. Most often, the best tuned values are in the range of 80-110. If you keep increasing P-gain and you start noticing disk oscillations in the hover, or unloaded FF descents, decrease the main cyclic gains 5 points and continue tuning the advanced parameters.

I-gain determines both how well the gyro will maintain attitude, as well as how hard it will fight your inputs. For the most connected feel you'll want to tune in the lowest I-gain possible, while still maintaining an acceptable level of attitude hold. I tune my I-gain by doing moderate speed passes and taking my hand off the cyclic stick. Watch carefully how well the disk holds attitude as the heli flies down the flight line up and down wind, right, inverted, as well as sideways. If the disk drifts up, and the heli slows down considerably, increase I-gain 2-3 points. I found values in the range of 90-105 produce the best compromise between attitude hold and connectedness. Values higher than this range will feel increasingly disconnected and robotic, and may even cause low-frequency oscillations and bounce back on stops. Value in the 60-90 range feel extremely quick and jittery, but may be well suited for smack 3D flying style.

D-gain similar to the discussion for the tail, this parameter controls stops. You need to test fly both quick jabs to the cyclic stick, as well as continuous flips/rolls and observe the stops. If the stops bounce, you can increase D-gain, and if they wobble, or coast, decrease it. However, if the disk stops cleanly, but just feels a bit vague, increase the Deceleration value and leave D-gain alone. Caution If you're using ZYX firmware 3.5, do not go above 20 for the cyclic D-gain, as this can cause violent oscillations.

Final tests
The most conclusive test of cyclic feel comes in stirring maneuvers, such as piroflips. If you can't fly these, don't worry about it, but if you can, try them out really slowly and deliberately. Keep that piro rate low, and carefully sync the cyclic stir, then slowly increase the piro rate and piroflip as fast as you can controllably- if you feel like the gyro is fighting you, increase P and decrease I-gains 2-3 points. If the cyclic feels inconsistent or sloppy, decrease P and increase I a bit.

Revisiting the tail
Now that you have your cyclic set up to the right feel, it's time to check the tail just to make sure it's perfect. One of the best tests you can do is sideways (aileron) tick-tocks. Do these with the starboard side down (i.e. the TR facing the ground). Keep them swift and tight, and observe if the tail drifts. If you notice a CCW drift, increase your governor gain , or add 1 point to the Coll>Tail and Cyclic>Tail precomp values. But be aware that the best tail performance is always a balance between how well your motor maintains HS in hard maneuvers and the gyro pre-compensation. There's really little any gyro can do if you're shedding 200-300 RPM with each collective move
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Last edited by Dr. M; 01-04-2013 at 01:26 AM..
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