500 Trex 550e V2 Tail Wag:(

[Graham Lawrie]

Right guys, I changed the main shaft bearings on my 550 and spooled up. Just as it is about to lift off just above half throttle, the tail starts to wag violently

I have done the following and it has not made a bit of difference:

1. Removed tail rotor completely and checked all bearings and movement: smooth as smooth.
2. removed torque tube checked for alignment/bend and bearing.
3. Changed main shaft bearings.
4. Gyro settings on DX6i up and down as high at 85 and as low as 58 no difference at either end of the scale.

I am contemplating doing the whole 3gx set up??

As always any suggestions welcome

 

[Tony]

You have a DX6i and a 3GX, so I'm assuming you are running a separate Rx? If not, you must. And make sure your gyro channel is on channel 5, or Gear. Verify that your wires are in correctly. This is a tail gain issue. Only other thing that woudl cause it is something sticking on the tail slider or your tail blades are backwards.

 

[Graham Lawrie]

Thanks Tony but everything is fine and separate RX just cant figure it out. I tried to avoid a strip down but did it as I was running out of ideas. Think it is a dreaded 3gx issue, but not sure ??

 

[Tony]

what is your tail gain set at?

 

[Graham Lawrie]

Where on? the tx or the 3gx?

 

[Lee]

The last two instalments of RCHN podcast have dealt with gain issues and PID settings.
There may be a nugget of info in there that shine some light on your problem.
Violent wag can be induced by a head problem rather than a tail issue.
And as it was the head bearings you changed, there could be the place to look further.
It could be an imbalance in the head.
Have you tried replacing the bearings you removed?
Sounds like you have tried everything else.

 

[Graham Lawrie]

Hi Lee, I changed the bearings
Just put it on the laptop and when I flick the gyro switch the rudder parameter does not change in the programme? It stays at maximum 120?

I have tried raising and lowering the values and it does not change

 

[Graham Lawrie]

I am now stripping the tail down completely

Struggling to get the umberella gear off

 

[Lee]

If you say the gain is stuck at 120, surely that is the issue?
I really don't like this 3GX the more i hear about it.

 

[Tony]

IMO, the 3GX is for those that are just getting into FBL. However it's a double edged sword. It's cheap, but you will have to work with it to get it right.

 

[Lee]

There are much better Entry level Units out there. All i hear is issue after issue with these things.
The Robird gets great reviews
The KDS EBar
ZYX S
CX1000
All of these seem a better/cheap/easier to program option than the 3GX.
Just my observation from the hundreds of posts i have read.

 

[Tony]

I suspect the reason you hear nothing about issues, it all about quantity. No one ever posts when things are going right, only when things are going wrong. So you never hear about the good things that are going on. But you are right, the other gyro's out there are much better, such as BX and Ikon.

 

[Graham Lawrie]

I stripped down the tail, put it in the freezer to shrink the metal and the shaft came out very easy

On inspecting the tail rotor shaft assembly there are signs of wear on the shaft and bearings Although smooth in operation I think the play is excessive enough to cause vibration

I really don't like the 3GX, it is the gyro that has caused me the most issues. I have parts and bearings coming for the overhaul, but it does not change the rudder issue in the software
I have removed all wires and I may change the gyro next pay day(2 weeks).

 

[Lee]

I'm buying a new MSH Brain from a shop in Italy.
They have them at the same price as in the States but without the customs tax problem.
Will sell my AR7200BX once I have that.

 

[Slobberdog]

Where you getting the brain from Lee, might be interested in one if I can get it for a decent price

 

[Lee]

If i tell you, I'll have to kill you


http://www.helypassion.it/eng/scheda.php?id_prod=470&valuta_select=&Msh-Brain-Flybarless-System-New

But there better be one left for me LOL

 

[Graham Lawrie]

I like the brain, but too rich for me I might try the other options Lee mentioned

 

[Tony]

Lee, can you not sell Graham your 7200? I can assure you Graham, you will LOVE that gyro!!! Very simple to set up, and it just WORKS lol

 

[Graham Lawrie]

I have one already Tony on my 450 I swapped the 3gx on that for it

 

[Graham Lawrie]

The helicopter fairy arrived today

2 x Tail Booms
1 x Torque Tube
1 x Tail Slider Bearing
1 x Black Umbrella Gear set for tail
Waiting for new bearings to put the tail together. Changing the main shaft as well as I have 4 spares Giving the 550 a wee birthday of new parts

If the wag is still there I may cry enjoying the build