zyx help please

[mrmurder1975]

just finished building my little hk250gt and installing the zyx. everything is moving in the correct way,the swash compensates in the right way but when i bring it to the hover,the whole heli wags,like a dog shaking off water from its coat,for want of a better description,and its a really violent wag.....scared the crap outta me i dont mind saying! dont really want to try it again until ive found out what i need to adjust and by how much. if anyone can help me out please?

im not a new pilot but i am new to fbl systems,so please keep it simple,im finding it all a tad intimidating at the moment!!
thankyou.

i should add that im currently using the soft 3d standard settings....

[InFocus]

On roll and pitch gain, go down 5 or 10 flashes for each. (blue flashes lower gain).

[iflyraptors]

The Total Gain Roll and Total Gain Pitch need to be decreased.
However do check the Collective value first. If you are using the USB interface or the programming box then check the value for the Collective Pitch Range. It should be 60 to 80. If below 60 then I would suggest moving the balls on the servo arm inward.

[Mikej]

In which axis does it wag - if it is the tail reduce the Gain in the Tx as per usual gyro, if it is the cyclic then reduce the cyclic gains.

Which servos are you using ?

[mrmurder1975]

hey folks,thanks for the replys. sorry,i should of mentioned im also using the usb to programme it.love how easy it is to programme with the usb...until i click the advanced menu anyway,then im a bit lost!

it shakes hard on the roll axis,so hard that its totally unflyable,its only been off the ground for a total of about 5 seconds,and both times ive only just managed to put it down in time to avoid trashing it..its that violent.

im running hxt900 on the cyclic and ds420 rudder (had to keep to a non existant budget!) i know these servos are not ideal for this application but it was those or nothing!

assuming my collective range is ok (cant think at the moment,but i think its in the range mentioned) i have the links mounted to the second from last hole furthest out on the arm,this was the only configuration to give me straight up n down links to the swash.

which settings do i adjust exactly on the advanced menu to bring it under control and by how much? bit confused by roll i,roll p,pitch i ,pitch p etc....

an uneducated guess would point me to adjusting the roll gain,but i honestly dont know for sure. thanks for the help.

[Mikej]

Using those servos you will need to reduce your roll and pitch gains to about 25 - based upon my experience of using metal-geared equivalents of those. Also check that you have your servo setting at 250mhz (from memory) for analogues on the cyclic and digital on the tail

[mrmurder1975]

thanks mike. is it the p,i or d gain numbers i need to reduce? still confused! lol

[iflyraptors]

mrmurder1975: In the USB software the first screen has sliders for the gain of the roll and pitch. The default is 40. Slide the control down and you will see the number below it change.

[mrmurder1975]

ah bugger!! i already adjusted the advanced menu numbers! it has improved the situation though! i can now get it off the floor without the violent shake,but its not very easy to control,on takeoff it wants to go left and back (normal for fb i know,is it the same for fbl though?) so i compensate on the sticks for it,but it seems very disconnected...maybe if i raise the numbers by 5 points that would help? im guessing here lol.
but anyway,i will go back to the advanced menu and put them back to default and then just change them on the normal screen with the sliders. thankyou!

[mrmurder1975]

i reset numbers in the advanced menu and i raised the numbers by 5 (to 35) on the first screen and its a bit better. but i am having to give constant up on the elevator to stop it coming back towards me when i try to hover it. my swash seems level (eyeball) and even if it wasnt completely level,surely the fbl system would correct it to counter the backwards drift? could use some input on that issue please.

also,ive just noticed i have 7 clicks on subtrim (which i dont remember setting!) in the tx (dx6i) on the rudder and the aile....i cant remember if subtrim is a no no with this system or not? i think subtrim is a no no on any fbl system i seem to remember reading somewhere...cant quite recall though. if anyone can advise please?

thankyou.

edit

ok,answered my own question. you can not use trim or subtrim with a fbl system. at least the zyx anyway.looks like im going to have to remove the subtrim and adjust for 90* via the gyro like i should of in the first place!...hopefully this might also sort the backwards drift im getting too! we can but hope...

[Busher]

i cant remember if subtrim is a no no with this system or not? i think subtrim is a no no on any fbl system i seem to remember reading somewhere...cant quite recall though. if anyone can advise please?

You do use subtrim, but not after you have set up the model.

Reset all trims and subtrim to zero to start, i usually use a fresh model and set up from a factory reset to make sure nothing is set

In the monitor screen look at the way your sticks influence the sliders, get the direction of the slider to follow the direction of the stick, if they dont use servo reverse to match the directions.
Then look at the centre positions of your controls, let go of the stick and see if the reading on the screen is showing "0" if not use the subtrim till they do. Collective pitch is different, set a staright (0,25.50.75.100, ) pitch curve in your set up put your stick at 50% on you tx screen and leave it there, you should 0% on screen if not use subtrim to get it there, then use epa / trav adj to get 100% each way.
Then look at your controls and move the sticks and see if you have 100% each way on them, if not use EPA adjustment or travel adjust (depends on TX) until you have 100% each way on all controls. After that you have told the unit what your true centres are, do not touch trim or subtrim after that,

Set your linkages on the swash to give near as possible a level swash with equal throw each way, then do the setup on the gyro screens, small adjustments and servo reversing is all done now on the gyro screens, final leveling of the swash can be done on the servo trim screen to get a perfect level swash and equal throw each way. I set 8 degs each way for cyclic controls and 12 degs each way for collective on a 450 so maybe a bit less is required on a 250, but just get the max cyclic you can get without binding and I wil bet you are not far off the figures I set. if you get a proper mechanical setup done first then the gyro will have less work to do to keep the heli straight giving more power to its brain for maximising the flight performance. The rest is about enjoying the flight.

Also may I ask what head you are using on your heli (250?), and if you have checked the heli isn't vibrating heavily because that will cause you probs with drifting and shakes etc.

[mrmurder1975]

hiya mate.thanks for all that info. i think i did it all right first time round,but i think i might just re set the whole lot and start from scratch,just in case i messed something up along the way. im running the tarot head. i know my heli is not completely vibe free,mainly due to a notchy belt drive pulley,came out the box like it but i do have an align one on its way.should of arrived today as it goes but it didnt.hopefully tomorrow!

[mrmurder1975]

ok, well i reset the model in the tx and also the memory in the zyx. but im still getting the heli constantly wanting to come back towards me.its also generally pretty unstable,im having to give a lot of stick input to try and keep it in one spot,which i can only do for a second or 2 before it comes back towards me anyway.

is there anything i can adjust in the settings screen to stop it wanting to come backwards me all the time?my swash is level but it feels like it needs a good dose of ele subtrim to keep it where i want it!

im currently running 35 on the pitch and roll gains which may still need to be raised to combat the instability.
And 70% dr and 40% expo in the tx.
ive also mounted the zyx on 2 of the foam pads (in position 3) to try and cancell out any vibes getting to the unit which was a slight improvement,stability wise.

feeling very disillusioned with this unit,although it prob down to my set up and/or vibes thats making it act up.really wanted it to be pnp like it is for most other people,should of known it wouldnt be that easy for me,it rarely is!

[Mikej]

Originally Posted by mrmurder1975

ok, well i reset the model in the tx and also the memory in the zyx. but im still getting the heli constantly wanting to come back towards me.its also generally pretty unstable,im having to give a lot of stick input to try and keep it in one spot,which i can only do for a second or 2 before it comes back towards me anyway.

A few things to check ...

* Have you set your sub-trims in the Tx so that the monitor screen shows zeros when the sticks are in their 50% position? Have you also set the EPA's to give +/- 100 at full movements?
* how is your CoG ?

Originally Posted by mrmurder1975

ive also mounted the zyx on 2 of the foam pads (in position 3) to try and cancell out any vibes getting to the unit which was a slight improvement,stability wise.

It is generally felt that these units work better when firmly mounted - if you have any vibes they will also affect the unit adversely. Rather than mount it in a manner to reduce the impact of vibes, you really need to get rid of the vibes and mount it firmly

Good luck,
Mike.

[mrmurder1975]

Originally Posted by Mikej

A few things to check ...

* Have you set your sub-trims in the Tx so that the monitor screen shows zeros when the sticks are in their 50% position? Have you also set the EPA's to give +/- 100 at full movements?
* how is your CoG ?


It is generally felt that these units work better when firmly mounted - if you have any vibes they will also affect the unit adversely. Rather than mount it in a manner to reduce the impact of vibes, you really need to get rid of the vibes and mount it firmly

Good luck,
Mike.

hey mate,thanks for the reply. one thing i do keep forgetting to mention in that on the monitor screen,on a couple of the settings..the aile and the pitch i think it was,i cant get them to stay at zero.they flicker between -1 and 0...there is no 'sweet spot' to get them to stay firmly on zero...if i adjust too far one way in goes into -1/-2 or the other way goes into +1/+2...the only way i can have them is to have them flicker between -1 and 0. is that normal? i assumed it was so just went with it....its the same when i adjust the endpoints,it flickers between 99/100 or 100/101....

ive never had much luck in tracking down vibes in any of the helis ive owned,i find that process very difficult to achieve with any success,i always end up chasing my tail until i end up giving up on the heli or just living with the performance issues the vibes create.i know you are 100% right that i need to get rid of the vibes to get the best out of thge zyx,but honestly,my heart sinks at the thought of having to go through that whole process again. chasing vibes in the worst aspect of this hobby imo,andi hate it with a passion!

edit.
forgot all about c.o.g,theres something else to check,cheers mike.

[Mikej]

Originally Posted by mrmurder1975

hey mate,thanks for the reply. one thing i do keep forgetting to mention in that on the monitor screen,on a couple of the settings..the aile and the pitch i think it was,i cant get them to stay at zero.they flicker between -1 and 0...there is no 'sweet spot' to get them to stay firmly on zero...if i adjust too far one way in goes into -1/-2 or the other way goes into +1/+2...the only way i can have them is to have them flicker between -1 and 0. is that normal? i assumed it was so just went with it....its the same when i adjust the endpoints,it flickers between 99/100 or 100/101..

That should be fine - you're close enough

Originally Posted by mrmurder1975

ive never had much luck in tracking down vibes in any of the helis ive owned,i find that process very difficult to achieve with any success,i always end up chasing my tail until i end up giving up on the heli or just living with the performance issues the vibes create.i know you are 100% right that i need to get rid of the vibes to get the best out of thge zyx,but honestly,my heart sinks at the thought of having to go through that whole process again. chasing vibes in the worst aspect of this hobby imo,andi hate it with a passion!

edit.
forgot all about c.o.g,theres something else to check,cheers mike.

I always start with the Feathering Shaft and Mainshaft, then check the tracking, that is usually 80% of the places that I get problems, then things like main gear, tail rotor shaft and if I still haven't found the culprit I'll look at the belt, loose boom supports etc. - but agreed it can be a pain

Cheers,
Mike

[mrmurder1975]

ah well im glad that flickering between the numbers is not a problem.started to wonder if it was a fault with the unit or my tx.
ive started trying to find the vibes..shortly after i posted earlier the postman delivered the new main gear and tail pulley system.

the main gear i got with the kit was junk and so was the pully...both really notchy. anyway,replaced both and the head and the belt both turn a lot smoother now,which has helped a fair bit...its still doing what i described earlier,it likes to swing around a lot,a bit like a pendulum, but not as rapidly now.

i have just noticed my main shaft seems to be very slightly off true now,think i might of bent it trying to get it down through the main gear.so next job is to replace the main shaft,but that will have to wait until next week now as the mrs has just cleared out my bank

But on the plus side,i seem to be making some headway towards getting this twitchy little thing stable.hopefully a nice straight main shaft will be the final piece of the puzzle.

while im here,can you let me know if im doing the setting the pitch bit on the screen correctly? im not sure i get how you do it. i have been getting the blades at 0 at mid via the grip links,going to full stick and moving the slider on the screen up with a view to it increasing the pitch on my blades....but it does not change the pitch of my blades when i move the slider,and the result is the same if i try to set negative in the same manner....can you explain the correct way to do it on that screen please? thats about the only part of the programming software im unsure about now. thankyou!.

[Busher]

Originally Posted by mrmurder1975

while im here,can you let me know if im doing the setting the pitch bit on the screen correctly? im not sure i get how you do it. i have been getting the blades at 0 at mid via the grip links,going to full stick and moving the slider on the screen up with a view to it increasing the pitch on my blades....but it does not change the pitch of my blades when i move the slider,and the result is the same if i try to set negative in the same manner....can you explain the correct way to do it on that screen please? thats about the only part of the programming software im unsure about now. thankyou!.

You have it right, the pitch will not move on your heli, it stays put, but if you move your stick to the extremes you will find that the overall throw has been adjusted in relation to the slider. If thisis not working you are reaching the limits of the system, the only way after that is longer servo arms or increasing the atv a tad, but do not go to far with the atv.

One more thing though, I am wondering if you have the unit set right on the heli, by this I mean is it 90 degrees to the mainshaft, if it is tilted this may induce the backward throw that you are finding, if all is ok I would cahse you vibes if there any left

[mrmurder1975]

Originally Posted by Busher

You have it right, the pitch will not move on your heli, it stays put, but if you move your stick to the extremes you will find that the overall throw has been adjusted in relation to the slider. If thisis not working you are reaching the limits of the system, the only way after that is longer servo arms or increasing the atv a tad, but do not go to far with the atv.

One more thing though, I am wondering if you have the unit set right on the heli, by this I mean is it 90 degrees to the mainshaft, if it is tilted this may induce the backward throw that you are finding, if all is ok I would cahse you vibes if there any left

ah right,thanks mate.that makes sense. that would also explain why my pitch servo arm was touching the main gear at its lowest point,i had evidently increased the servo throw to its max while trying to make that slider move the pitch and caused this...could not figure out why that was happening for the life of me!

the unit looks pretty square on the heli,but thats something else i didnt think of,that maybe its not quite level. going to dig out my little bubble level and find out for sure,thanks mate.

[mrmurder1975]

seems you were right about not having the unit quite level....although it looked it in relation to the frame,it seems it was tilted back a tad. i checked and leveled it with a bubble...the weird thing is,it looks like its tilted down towards the nose of the heli now...well,it is tilted down towards the nose of the heli and the vert side of the unit is not 90* to the main shaft,but the bubble is at center and the backwards drift has all but gone......weird or what?!

anyway,its still pretty unstable in the hover,its a struggle to keep it in one spot. i hope this is due to the main shaft being out of whack and once ive replaced that it will be much better.

next week is going to be a long time coming waiting for some money to go in so i can get the shaft!