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How to tune out the annoying tail kick?
https://www.spirit-system.com/phpBB3/viewtopic.php?f=20&t=1457		 Page 1 of 1
Author:  curmudgeon [ Sun 29. May 2016 18:23:19 ]
Post subject:  How to tune out the annoying tail kick?
I am using the Spirit governor. The head speed tends to bog a bit when I apply "harsh" collective and the tail kicks about 20 degrees counter clockwise (not able to keep up with the sudden main rotor torque). I am using the same helicopter and motor I was using with the VBar, and I was not experiencing this issue then, so I know that my power system should be able to handle it. How do I tune out this annoying tail kick?
Author:  jgiannakas [ Sun 29. May 2016 18:27:49 ]
Post subject:  How to tune out the annoying tail kick?
Increase the tail gyro gain from your TX till it starts to wag then back off a few points. The tail kick should be completely eliminated then

The spirit units can take a lot more gain on the tail than the vbars so don't be afraid to crank it up
Author:  ZeXx86 [ Sun 29. May 2016 18:29:05 ]
Post subject:  Re: How to tune out the annoying tail kick?
First from all, it is important to tune governor correctly. Without this, the tail can't operate well.

But generally, I can tell you what to configure so that the tail will work well.
What helicopter and rudder servo do you have? What Rudder Servo Frequency, Pirouette Consistency and Rudder Delay you have configured?

Remember, that gyro gain values between VBar might be very different. So you have to re-set Gyro Gain for the unit as high as possible.
Author:  velocity90 [ Sun 29. May 2016 18:50:45 ]
Post subject:  Re: How to tune out the annoying tail kick?
Delete
Author:  curmudgeon [ Sun 29. May 2016 19:08:47 ]
Post subject:  Re: How to tune out the annoying tail kick?
First off, thank you for the quick response. I am very happy with the Spirit units I have (Spirit Pro's x4). The reliable rescue feature has helped me take the fear out of trying new maneuvers. I'm actually trying new maneuvers with the heli's before even attempting them on the sim. Awesome units.

This helicopter includes:

1) Synergy E5 kit swinging 556/96 Rail blades at 2400rpm governed by Spirit.

2) KDE 600XF 1100 Kv motor

3) Single 7S 65C 4400 mah LiPo

4) 12T motor pinion and 119T main gear (1:9.92 gear ratio, but set to 9.90 on Spirit)

5) Jeti 8S 120A ESC (telemetry, rpm out wire, internal BEC). I set the BEC to 7.5V. I'm also using the R2 Prototyping Super Capacitor unit as backup. Jeti ESC set to Fast Response which is the recommended setting when using external FBL unit governor

6) Jeti DS-16 radio

7) Tail servo: Futaba BLS 256HV set to 333Hz Frequency, 760us pulse

8) Spirit Throttle Frequency set to 120Hz

9) Spirit Throttle range set to 1000us min and 1900us max

10) Spirit Governor Fine tuning: Spoolup Rate: Fast; Spoolup Rampup: 50 us; Governor Response: 7; Holding Performance: 5

11) Rudder Gain set to 75% on the transmitter

12) Rudder Common Gain set to the default 1.00x

13) Rudder Delay: 5

14) Rudder dynamic: 6

15) Rudder-Revomix: 0

16) Pirouette consistency: 165

17) RPM Sensor Filter: 1 (the Spirit is not logging any rpm noise issues with this low setting)


Please, let me know what you recommend.

Thank you
Author:  ZeXx86 [ Sun 29. May 2016 19:13:34 ]
Post subject:  Re: How to tune out the annoying tail kick?
Thank you for the info.

I recommend to set:
Pirouette Consistency: 185
Rudder Delay: 0
Rudder Common Gain: 1.2x

Then just increase Gyro Gain as high as possible until you will see oscillations.

Next time you can just save the profile (4DS file) and attach it here. Then we can view all your configuration directly here in the forum (with online viewer).
Author:  curmudgeon [ Sun 29. May 2016 20:19:01 ]
Post subject:  Re: How to tune out the annoying tail kick?
No more tail kick on "harsh" collective. Awesome!

I made the changes you suggested (increase piro consistency to 185, decrease rudder delay to 0, and increase the rudder common gain to 1.2x). Interestingly, the rudder servo buzz disappeared when I increased the rudder common gain to 1.2x. It is just quiet now. The tail servo will buzz below and above 1.2x. I'm not sure what explains this, but I digress.

I increased the transmitter gain up to 85% but I was still getting tail kick. Then I increased it to 95% and the tail kick went away. Since I was not getting tail vivration, I increased it to 100%. No tail wag initially, but it began wagging left and right with high frequency doing back to back pitch pumps, so I decreased it back to 95%. I'll leave it at 95% unless there is a reason to change it.

Now onto tail "lag". When I do pitch pumps, the tail lags the body of the heli. When I do a pitch pump, the front of the heli will go up, but the tail lags down and then catches up. I know other FBL units have some tail lag compensation parameter, but I don't know what to adjust on the Spirit.

How do I eliminate this tail lag?

Thank you
Author:  ZeXx86 [ Sun 29. May 2016 20:33:08 ]
Post subject:  Re: How to tune out the annoying tail kick?
Great. The issue can be certainly improved, but still, if the RPM is not holding well, it highly affects the tail performance.

If you can see that the helicopter is not moving well during pitch pumps (there is a log in elevator or aileron axis), then there are at four possibilities:
1. servo center positions were not configured precisely/correctly with Cyclic Leveler.
2. CG is way too off - battery is too heavy or too light or positioned in a wrong place.
3. One of the servo has non-linear travel
4. Cyclic Gain is too low (60% should be enough)

Spirit unit has automatic corrections for such behavior, so if you can still observe such issue, then there is really something wrong.

Mostly the issue is case 1 and 2.
If it is 1., then I recommend to start with Subtrim (tuning) menu.
After enabling, all the servo arms must be in the center position (as close as possible). At the same time the swashplate must be perfectly level and at the same time you should measure 0° between the main blades.
Author:  curmudgeon [ Mon 30. May 2016 0:31:27 ]
Post subject:  Re: How to tune out the annoying tail kick?
1) I leveled the wash at low, mid, and high stick with the TrueBlood (tripod style) swash leveler.

2) The center of gravity is pretty good. If anything, it is slightly nose heavy.

3) These are Futaba BLS 255HV servos. Since I was able to level the swash at high and low stick with minimal Spirit adjustment, it looks like all three servos are working equally well.

4) I have the Cyclic gain set to 55%. I will bump it up to 60%. It started to rain pretty badly, so I will have to try another time.
Author:  ZeXx86 [ Mon 30. May 2016 7:10:28 ]
Post subject:  Re: How to tune out the annoying tail kick?
Thanks for the info.

ad 1) But are the servo arms really precisely in the center position when you activate the Subtrim (tuning) option?
If no, then this could be the problem too.
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