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Old 05-12-2012, 12:53 AM   #1
hankcp
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Default Tail Wag in Flips

Following joe1l's sticky, I'm setting up my TRex 550 (DS610/DS650), and I'm encountering a slight wag when I flip. It happens when the tail is down during the flip, and it get's worse as I increase ANG.Rate on the elevator. Lowering the tail gain doesn't change anything, and FFF is solid. Thoughts?
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Old 05-12-2012, 01:03 PM   #2
Steve Evans
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Do you get this if you get some altitude and do the flip with zero collective?

Steve
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Old 05-29-2012, 02:54 PM   #3
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Steve, Thanks for the reply. I did as you suggested and tried zero collective flips. It was still there. I decided to change some stuff up....

A little background. When I first started with the CGY750(1.2), I started in Flt.Mode 3. I had some wobbles, but mostly the heli felt vague, even with expo all the way down. I had low gains, and my Swash AFRs were out of range. To remedy this, I used joe1l's method as described in the sticky. The heli was trimmed via Ntr, and I used the values for various gains. The heli was way better. However, as in the first post, I had a "tail wag" when flipping. It turns out that I was miss-diagnosing the symptom. I was actually getting a Ail wobble.

I wasn't fully content with setting up the gyro with so many changes to default values, so I went and looked at Ben Minor's method. Still using joe1l's trim flight, I just set Flt.Mode 3 and upped AVCS.Dmp 100. Now, the heli was just as good as before, but without a lot of Expert menu changes. It was basically default except for one change. I was still having the Ail wobble so I found that lowering D.Gain would stop that. Now, two changes.

Fast forward to today. I was unhappy that my Ele AFR was out of range, so I moved the balls on the servo arms in one (I run Align metal arms). I adjusted the pitch curve so that I could raise Pit AFR. My AFRs ended up being:

Ail 50
Ele 56
Pit 50

Those were great numbers (with 50-60) so I was happy with that. Then, I decided since AVCS.Dmp caused the greatest improvement, I went straight to Flt.Mode 5. I removed the Expo, and off I went. First flight out, and I was really happy that with a default flight mode could achieve. I started upping the gains. I ended up at:

Rud 55
Ail 90
Ele 100

As I was upping the gains, I noticed a fast Ail wobble. I dropped D.Gain 100 -> 75, and it went away. Also, I had a strong bounce back on flips so I upped Stop Delay 120 -> 180, and it seemed to cure it. I didn't think to try, but I will play with the Ele gain next time.

Overall, I'm happy with the way the heli handles now. I just never thought to run Flt.Mode 5 since I'm not a "aggressive" 3d flyer, but it feels better to me with those settings. I think the biggest take away is how much AVCS.Dmp affects performance. The default 98 seems too low.
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Old 05-30-2012, 09:41 AM   #4
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Thanks for the update. This and the servo killing issue in the other thread is why Futaba really need to rewite the manual from scratch in English
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Old 05-31-2012, 12:10 AM   #5
hankcp
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Yeah, the manual leaves a lot to be desired.

Today, to see if things would be different, I tried Flt.Mode = 1. I raised AVCS.Dmp on Ail and Ele to 100. After a couple tuning batteries, I was at:

AVCS.Dmp 100 A/E
Head Resp 3/2 A/E
Expo 0 A/E
D.Gain 50 Ail
Gyro 100/100/55 A/E/R

I think I might like this FM better. It does feel a little less aggressive, like I don't have to make as many corrections. Even the tail bouncing up and down went away without any Stop Delay changes.
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