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Home✈️Aircraft🚁HelicopterBeginners Corner › Tail oscillation
08-06-2007 12:15 AM  13 years ago
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lyenokio

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LA,CA USA

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Tail oscillation
I have a Trex 450S V2 with a Futaba 6exh and GY401 Gyro. I have watched videos , listened to experts about rigging and so far I cant seem to fix this side to to side rapid oscillation of the tail rotor when I bring the throttle up. I have rigged this heli for a total beginner with no ccpm capabilities. The pitch is maxed out about 11 degs full throttle and 0 with no throttle. I have watched all Finless Bobs videos on setup and I still cant get rid of this problem. All my curves{Throttle/Pitch} are set relatively per Bobs video. I dont have a tach but,is it possible that I am getting to much head rotor speed?This thing really winds out when I advance the Throttle. I have tried adjusting my gyro until Im blue in the face.... My current Throttle curve is a 5 point curve and set at: 0,50,60,70,90 . My pitch curve is pretty much linear. I have the stock Align brushless motor and 35 amp speed controller too.Ideas anyone
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08-06-2007 03:21 AM  13 years ago
herby8860

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Conneaut Ohio

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What amount of gyro gain do you have in idle up, could be your gain is to high.
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08-06-2007 03:28 AM  13 years ago
mikeflyz

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Westlake Village, CA

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I hijacked this from your other thread.
I have my channel 5 switch in the up pos.{A: GEAR}and the radio is setup in the GYRO setup menu to +90%. With the switch in the down pos. {H:GYRO}I have the Gyro set to -60% in the setup mode. I noticed with the battery plugged in and the radio turned on the GY401 red lite is flashing on/off. I believe that the gyro is not in HH mode. My gyro delay is set to 30 and my limit is set to 100. As I mentioned before the gyro had to be reversed as did my #4 servo to get the chopper to fly.I have my EPA for ch 5 set to 100% and my ch 4 epa set to 100 % -/+ with a Hitec 65 tail servo.
Fortunately, there is a simple and happy ending. Simply put, you're running way too much gain.

With your switch in the UP position as you've said in this other post, and the GYRO setting at +90%, that is clearly way too much, even for a high speed digital servo. I have mine at 50% gain and I'm running a 9650 on the tail.

The 401 needs to boot up in AVCS mode (heading hold) every time. From your previous posts, it sounds like it's not being done, where it's "blinking all the time." Your gyro channel (CH 5) should NOT be reversed. Put your CH5/Gear switch UP before plugging in the battery. That should do the trick to start up in HH mode.

On your GYRO page, start with +50% in one switch position (GYRO/ch 5 switch) and -50% in the other switch position. This will give you 50% gain in HH, and 50% gain in non-HH. Again, you must have the HH function ON when plugging the heli to the battery. After a couple of seconds, the red light should be on steady. If it's not, stop and investigate before going on further.

Your DS switch on the 401 must be OFF for your analog servo. Set your delay at 0 for now. Your limits should be set to reach the mechanical limits of the slider. If you're using a hole too far from the center on the servo, and have to reduce the LIMIT setting on the gyro below ~90% or so, use a hole closer to the center to get the limit at or above 100%.

If it still wags in the hover, you'll have to reduce the gain. This is accomplished by going back to the GYRO page, and decreasing the value slightly to +45%. Repeat the process until the wag stops.

If your gyro gain is excessively low (below +30% or so on the radio) and still wagging, switch the tail rotor servo to a faster one. Looking on your last posts, it looks like you're running a HS65. Is that still the case? The best performers are the digital servos, but a HS81 also does well; it's faster than the HS65.

Check for binding and slop from the tail rotor servo to the hub. There should be absolutely no binding, and only minimal slop.

You only need to mess with the delay when there is a momentary wag after recovering from a fast pirouette, and only for an analog servo.

There are many fields in LA where TRexs are around. I fly in the SF Valley, Sepulveda Basin as well as many others, and I'm sure you can get someone to test and inspect your heli.
Mike
MA Fury Extreme, JetCopter SX
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08-06-2007 05:29 AM  13 years ago
lyenokio

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LA,CA USA

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You Guys are correct about my gain in previous posts...WAS WAY TOO HIGH. I have since adjusted my gyro Mike and I managed to get things squared away.{Thanks to you} The gyro lite is on steady. I used your advice sometime back and all has been well.Im starting to understand things better now.I suffered a minor crash due to higher than normal wind gusts and an eager beaver pilot...Nuff said..LOL I have my delay at 0 and my gain is at +55 and -50. I still have to re adjust my limits post crash there still not perfect, but functional. This problem is weird..I followed Finless advice to the letter and the tail wag got worse. When I turn down the throttle curves and pitch curves the heli runs fairly smooth, but I find it difficlt to stay in a constant hover.Not enough pitch or throttle. As soon as I adjust the curves up to finless`s recommendations I get severe tail wag and a chopper that wants to literally takeoff to the moon. I have adjusted everything to all the pro`s specs and Im still getting this oscillation.Im still running the HS65 tail servo too.I guess tomorrow I will go over everything again from the beginning. Im watching Finless Bobs Gyro setup as we speak.I will prevail Im sure as long as I got you guys helping me out. BTW I did have this thing flying nicely before I ran it through my neighbors front door...Tough bird man!!! Only slight damage to the rotor main shaft...LOL. Have to fix my neighbors door though...LOL I will post my findings and settings tomorrow.
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08-06-2007 05:43 AM  13 years ago
mikeflyz

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Westlake Village, CA

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Okay, that info helps.

I still would like to know what kind of motor and pinion you're using. That will help me estimate your headspeed.

If it was flying pretty well before a crash, you can be sure that there is some hidden damage somewhere.

Is your gyro mounted securely to the airframe? I use a zip tie in addition to the foam tape. It shouldn't move much at all. Maybe increased vibration is rattling the gyro around.

The offer still stands to look it over for you. That may save you a lot of time.
Mike
MA Fury Extreme, JetCopter SX
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08-06-2007 10:50 PM  13 years ago
lyenokio

rrNovice

LA,CA USA

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Mike Im using the Align 430x and I believe it is the 13T pinion. BTW I used your gyro settings and rerigged the tail servo and I have been flying tail wag free. I redused the gain to +45/-45 and I set my tail throws up perfect. The crash moved the tail servo bracket over a little and screwed up my rigging. Im happy right now with the results. Even in the wind it flys nicely. I will have to meet up with you sometime at the basin and you can check my rig for me. I appreciate your help very much.Let me know when you fly and the directions and Ill see if I can make it....
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08-07-2007 01:22 AM  13 years ago
mikeflyz

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Westlake Village, CA

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Glad to hear it.

I'm back in town this week, probably leaving on Friday for IRCHA, so I'll PM you with details.

Mike
Mike
MA Fury Extreme, JetCopter SX
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08-07-2007 02:03 AM  13 years ago
lyenokio

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LA,CA USA

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Thanks again Mike.....Just finished flyin again...My rendition of flying anyway....Havin a blast...SO FAR...Check out my training wheels

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08-07-2007 02:26 AM  13 years ago
GyroFreak

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Orlando Florida ...28N 81W

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I had a tail wag on my Hawk Pro and it turned out it was my training gear was loose and sliding around a little. Tightened the training gear to the landing gear and problem fixed. Probably not your problem but thought I would throw it out for you to see.

Paul
I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?
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