450pro with a bit of a wobble

[Pj1969]

I know only a handful of people fly the TAROT zyx, but i am one and love them. Just recently after a rebuild, i've noticed a slight wobble noticeable when coming into land on my 450 pro, i've always had such a stable bird and have changed main shaft, feathering and all new bits after my crash. I have upped the head speed in normal to 70% and in IU1 to 85/90, but still got it. It's not a tail wobble, but more like the whole body. Any ideas guys on what to look at next??

[Rob Barnes]

Heve you checked your tail output shaft and your tail linkages, It may also be worth checking the pinion on the motor shaft to see if that is bent too. Process of elimination on some wobbles that sometimes don't seem obvious .

[Sesame]

As Rob said but also check the blade holders are not bent, you didn't say you changed those. On a 450 the head dampners can make a lot of difference may be worth swapping out for a spare set to see if it makes a difference

[Mike Sanders]

There is just a possibility that one of your cyclic servos has a bit of a problem. That would cause the whole body to shake.

[Mikej]

The wobble in descents with the ZyX is usually the cyclic gains slightly too high, but i they were ok before crash should still be fine. Check for excessive slop in servos

is the tracking ok still?

[Pj1969]

I changed the servo's as one was way too sloppy, i'll be honest, the ds410's are not as tight as they were, slight bit of play, but only a couple of thou. Mike i have turned cyclic gain down from 40 to 20 in the software, will drop it a little more, but like i said she was flying fine before hitting the deck. Like rob said, process of elimination and if turning the CG down doesn't work, it's either put up with it as she fly's well enough to handle or get some new servo's. Cheers for the tips guys

[Mikej]

20 is very low for the cyclic gains - I would try them at 25 and then gradually increase until you get the wobble.

If you have increased the HS that could cause this as it effectively raises they mechanical gain. I would try at previous set-up (same gains and HS) as a starting point, then reduce gains to 25 if you still have problem, and gradually increase them 3 points at a time until wobble re-appears

[Pj1969]

20 is very low for the cyclic gains - I would try them at 25 and then gradually increase until you get the wobble.

If you have increased the HS that could cause this as it effectively raises they mechanical gain. I would try at previous set-up (same gains and HS) as a starting point, then reduce gains to 25 if you still have problem, and gradually increase them 3 points at a time until wobble re-appears

So if i set the HS in normal to 65% and IU1 75%, put my gains back on 40 which i believe is standard and see whats what?? I will also check dampers etc and all grips, blade tracking is spot on, as is balancing. If she wobbles when coming in tail first to land, shall i bring CG down to start or up HS??

[Mikej]

That's a tricky one, if you raise the HS then you are effectively raising the mechanical gain - so doing the opposite of dropping the Cyclic Gains. However wobbles can be caused by a number of things for example Gain being too high or headspeed being too low (common on Trex 500s, but not so often on 450s).

The ZYX is prone to the cyclic wobble in descents if the gains are too high, hence the suggestion of going back to your previously good set up and dropping the gains to 25 and seeing how that affects things, hopefully it will stop the wobbles.

However if they just started after your crash then you really want to work out what is causing it - as others have suggested it is usually something bent causing vibes - the ZYX is fairly sensitive to vibes unfortunately, but works very well when they are tamed.

So if i set the HS in normal to 65% and IU1 75%, put my gains back on 40 which i believe is standard and see whats what??

Yes, that's what I would do

If she wobbles when coming in tail first to land, shall i bring CG down to start or up HS??

I'd start by dropping the gains to 25 (which "should" get rid of wobbles if gain related) then raise them by 3 points at a time until they start again, then back off by 2 points. Then try and work out is you have vibes from somewhere

[RcRotaryMadness]

Hmmm... my only question would be if the heli was flying fine before the crash then the tarot gyro must be setup ok and the wobble is from something bent or crushed in the crash that hasn't been spotted.
I'd guess something with the rotor head is bent.. the hub, a blade grip, the swash plate etc... all needs be stripped down and checked over including bearings and dampers.
Also have you inspected your servos after the crash? Are they all ok without any missing teeth etc.
By changing the settings in the tarot might just end up masking the problem rather than fixing it.

[Pj1969]

brilliant mate, i'll try that, i do love the zyx, its a cracking little gyro, thats why i stick with it. I'm pretty sure its these 410's, I've actually got some ds420's brand new not doing anything, think i may swap them for those if i cant find the source of the wobble. Cheers Mike, will let you know the out come

[Pj1969]

Hmmm... my only question would be if the heli was flying fine before the crash then the tarot gyro must be setup ok and the wobble is from something bent or crushed in the crash that hasn't been spotted.
I'd guess something with the rotor head is bent.. the hub, a blade grip, the swash plate etc... all needs be stripped down and checked over including bearings and dampers. By changing the settings in the tarot might just end up masking the problem rather than fixing it.

Yeah this is whats confusing, i've changed all the shafts for new just in case there was a little bend, blades are new,dampers were new only a few flights ago, only thing was the servo's, one jammed, so chnaged the gears etc and replaced one of the servo's due too being a little sloppy. She flys lovely in IU1 and doing circuits, just when coming into land i've noticed a wobble.

[Nick B]

Did you replace the main shaft bearings?

Had a wobbly logo 600 a few weeks ago,replaced the 3 bearings and she is now sweet again...one bearing was really shot!

[Pj1969]

Did you replace the main shaft bearings?

Had a wobbly logo 600 a few weeks ago,replaced the 3 bearings and she is now sweet again...one bearing was really shot!

Nick i've checked them and they seem fine, no play at all, just to make sure, i can put some new in as i have spares. Cheers mate

[Pj1969]

Well I think I've found the problem??? At low any high stick, she flys lovely, but at mid stick, for some reason that's when I get servo jitter!! After checking servo's i found that the aileron servo had a slight bit of slop in it compared to the others. For the sake of £3 I've changed the gears, cleaned up all the contacts and it appears to be better. I have also put in new, feathering shaft, bearings etc and after spooling her up with out blades on, seems a lot better. I have also set software and gains back to standard and if I can, take her to the field this weekend to fly. Let's hope the wobble gas gone