Agile 5.5 set up

[treff]

I'm having a problem setting up my Agile 5.5. Getting a nodding effect as if the cyclic gain is to
high. I am using Brain fbl unit. The problem I am having is one flight it is very smooth, no nodding and the next the nodding effect
shows up again. Could anyone with a Agile tell me what setting they run for the gain. I have tried from 40
down to 25 with little effect. I am beginning to think that something else is amiss. Thanks for any comment and
info. Cheers

https://www.flickr.com/photos/32758223@N00/14894223247/

[bigbladelittleblade]

My goblin 500 nodded when it was brand new, sometimes it's that things need to bed in for a few flights when new or it could be that your head speed needs increasing. Try increasing your head speed first and see if that stops it. It took around 10 flights on my Goblin before it stopped, now it's fine.

[tomatwalden]

Elevator nodding isn't usually a cyclic gain issue, it's a mechanical issue and affects lots of different helis and flybarless units. It's usually more prevalent at lower head speeds (ie. ramping up the HS reduces or removes it) and I believe is more common with a hard dampening setup.

Cyclic gain issues normally show up as fairly fast / severe "shuddering" of the whole heli in both the elevator AND aileron axis.

The link to your vid doesn't seem to work by the way ...

[treff]

Thanks to both for the info. Yes I have tried increasing the head speed and decreasing the cyclic gain but it does not make a lot of difference.
I think I may try adjusting the tail drive so that it meshes a little more with the main drive to see what happens. Thanks again

[pug907]

I had a similar problem with my Agile 5.5. Do you have a slightly warped tail spiral bevel gear?? If so, I changed mine after a chunk fell off (http://www.rcheliaddict.co.uk/sponso...ld-thread.html) and it didn't nod at all. I had upped the HS to 2500 which had some effect, but still a slow nod every now and again. If you struggled to get the tail gear mesh even all the way around, it is the warped one!! It's not that noticeably warped, unless you're looking for it.
Good luck, they are amazing helis, although mine destroyed itself at 10 flights old. Looks like a blade link snapped, causing it to cut it's own tail off .

Sorry Trevor, just noticed it was your post, you should have rung me again

[tomatwalden]

Thanks to both for the info. Yes I have tried increasing the head speed and decreasing the cyclic gain but it does not make a lot of difference.
I think I may try adjusting the tail drive so that it meshes a little more with the main drive to see what happens. Thanks again

If head speed makes little difference, you might want to try taking the head apart and making sure the dampeners have enough grease ...

[treff]

Thanks for that info pug907 yes I believe your right it's something to do with the mesh of the gears. Strange though because
some times it's okay then next flight, nodding. It's nothing violent and I have pushed the head speed up to around 90% I don't
know the speed but I think you can work it out from the pinion etc. I will have another look at the mesh of the gears it may be on the loose
side. Enjoying the heli but I must find a bigger field to fly in lol. Thank again

[ChrisB]

FWIW i have exactly the same problem with my 5.5 the noddding along with the tail fin vibration that you have,i am running a Jive in mine,stock gearing and i have tried very low to 100% flat out on curve and nod persists.

I am currently systematically pulling mine apart and checking everything.Different main and tail blades makes no difference.

Have run my V Bar cyclic gains down lower than i have ever run them on anything and it makes no real difference,my nod is there all the time though pretty much and if you are say flying along straight and its not nodding as soon as you pull up to say stall turn or loop it nods away again.

[treff]

Thanks tomatwalden and ChrisB, yes ChrisB exactly the same as mine tried changing head speed, cyclic gain but makes no difference. I am beginning to think main drive gear is warped
but I will try tomatwalden's idea and grease up the dampers and see what happens. It is strange that 3 people have now had this problem so I guess it maybe common to the design.
I hope not. Thanks again. If you find a cure drop me an email. Cheers

[ChrisB]

I will post any findings in this thread and likewise see how you get on.

I have the Agile 7.2 also and that thing is just awesome,so i know the potential of the 5.5.

Thanks for the suggestions offered also,i will check these areas as well.

[treff]

Yes hope we come up with a solution. I have not really flown it yet just hovered around trying to sort things out.
Thanks again.

[tomatwalden]

Interesting thread. I've been really tempted by the 5.5, but read some early reports of swash quality problems. If there's some form of design issue as well, that'd be a real shame

[ChrisB]

Yes hope we come up with a solution. I have not really flown it yet just hovered around trying to sort things out.
Thanks again.

Mines flown a few flights,of Aeros and 3D but they have all been kind of fact finding flights seeing what it does and doesnt do,also started off as 12s with mine but now dropped to 6s.

I have found i damaged one of the rubber torque tube bearing housings pushing them down the boom so maybe this is causing the vibes,dampers are my next plan of attack,i have the new rubbers for the TT so will swap these out first and try again.

Want to do one thing at a time to be sure what the culprit is.

[Martind]

Here's some good tips
Nelson Rodriguez - KDS Agile 7.2 and 5.5 build ti…: Nelson Rodriguez - KDS Agile 7.2 and 5.5 build tips. - YouTube
I've had about 20 flights on mine now. Still have the fine vibe but the head has a small nod at 2200rpm.
Mines on 12s
Sk3 4956-550kv
Cc 80hv
Sk540
HV servos
2x 6s 2700mah

[treff]

Thanks Martind. Well that's 4 owners of the Agile 5.5 who have the same problem. I am beginning to think there maybe some sort of design or machining issue
with this model. I wonder if there is any more out there suffering from the same problem