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PostPosted: Wed 25. Feb 2015 5:38:08 
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Joined: Fri 29. Aug 2014 23:22:42
Posts: 63
Location: Australia
I'm not getting a solid Tail hold on my little Trex 450 and it's not for lack of trying. What I'm seeing is a small kick to the right with positive pitch and then a vague slow kind of intermittent wag going on. The Tail feels really unconnected the whole time. If I keep increasing the Gain I just end up with Wag and it's still got the Kick and wander going on. Have tried an Align 525M, JR DS290G and a KDS N300 servo with the N300 best however still the issue persists. My mechanicals are smooth without any Binding. I've tried different holes on the Horn , I think I've tried everything but obviously missing something !!!
I'm wondering if I'm seeing a Vibe related issue although the Flight Log is clear and this is the second 450 I've installed the unit on and both exhibit the exact same symptoms.
I know lots of you have commented how well the Unit flys out the box however I'm really struggling to get it solid.
Got to get this sorted , it's driving me nuts !


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PostPosted: Wed 25. Feb 2015 8:35:04 
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Joined: Mon 29. Apr 2013 16:06:44
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Hello,

I recommend to set put ball link as close as possible to the servo.
Then don't forget to reconfigure rudder end-points.

The most important is to set piro consistency parameter. For Trex 450 it can be around 165.
Is the rudder control smooth if you want to move tail slider by hand (without blades) with running motor?

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PostPosted: Sat 28. Feb 2015 3:07:26 
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Joined: Fri 29. Aug 2014 23:22:42
Posts: 63
Location: Australia
Still not perfect however heading in the right direction now after realizing I had the Servo set to 50Hz !
Currently have an Align DS525m on the Tail which has always previously flown well on two different brand Gyros.
I've tried 8,10 and 12mm Ball positions and currently have it at 8mm.
Using a Delay of 15 , is that ok or not even close ?
Finding it hard to find the sweet spot for Piro Con and TX Gain to stop the small kick to the right and bounce back I'm still seeing without inducing wag.
Am running Chinese Weights so very little Tennis Racket effect with Tail Blades removed and spun-up. Could this require some parameter change to compensate ?


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PostPosted: Sat 28. Feb 2015 10:10:28 
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Joined: Mon 29. Apr 2013 16:06:44
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For this servo you can set 333Hz.
Is your Gyro Gain configured to the max. possible value?
Rudder delay may be fine approx. 10 for this servo.
What is your mechanical center [°] of the rudder when servo horn is at 90°?

Also are your RPM constant enough?

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PostPosted: Sat 28. Feb 2015 12:30:06 
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Joined: Fri 29. Aug 2014 23:22:42
Posts: 63
Location: Australia
Will set Frequency and Delay to recommended settings and fly tomorrow.
My Gain is just below inducing Wag at present however is a moving target if I adjust Piro Comp.
I'm seeing 0Deg Pitch when Horn at 90. Should I add a turn or two to get a couple Deg Positive Pitch at 90Deg on the Tail ?
Using a flat 100% TC with a reasonably high HS.


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PostPosted: Sat 28. Feb 2015 12:41:18 
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You can try 3-4° blades pitch, this can help you.

I am afraid but if you are not using governor with flat TC, RPM may drop a lot so tail demands are much higher.
In this case only revomix may solve the issue.

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