Hello, my problem is that my Evo50 doesent behave like it used to do.
After a very smooth crash, I changed the usual stuff, and after a month or so, it begins (after 20-30sec) to wobble( OSCILLERA in SWEDISH)? What can it be? Everything looks and feels normal until this comes around! My rpm is about 1700, and the rotorhead is just fine, well HELP ME!
Ive heard that it could be something wrong in the tail but, what do you think?

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The rotor hub could be bent. This is the aluminum part the bolts directly to the top of the main shaft. The plastic hub of the rotor head is bolted to it.

Blade 550X, T-Rex 450 Pro FBL

Hi, the hub is new, the main shaft is new, as I said everthing is just fine in the rotorhead, good balance and so on, I dont get it........

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Wobble

Is this a front to back or left to right movement ?

Is it a vibration in sync with the headspeed or a rather slow ossicliation ?

(after 20-30sec)

Does this wobble occur before, upon, or after spoolup ?

Is there a descernable change in engine power when this occurs ?

Typically a slow oscillation will occur with slow headspeed. "1700 rpm" is relatively low since the EVO's come alive at around 1950 rpms. A bent flybar can also manifest itself in the heli exhibiting a up and down ossicilation. Another thing to check is the "bird cage" (Stabilizer control arms). If these are not in alignment, it will appear that your paddles are in alignment, but at the rotorhead spins, the mis-alligned "birdcage" will produce a up and down movement of the heli.
Check Dampeners.

Provide more info and I am sure you will get sorted out.

-elvis

Hi, the stabilator arms is fine, and there is no direct movement in this high oscillation- the heli is not going at any special way- it just is nervous on the spot(if that is what you mean?) . It begins after 20-30 sec after every startup, and there is no differnce in the motor what I could hear( a friend of mine tried the heli(he has flown those things over 10 years, and had no idea either).We checked most of the heli but
couldnt find out.....

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Well, something is either bent that you missed when rebuilding, or something is out of balance.

Did you balance the head when you put it back together? But if it was ok for a month after the rebuild, that probably isn't it...

Could be the dampeners in the head are worn out. A little wobble when spooling up the rotors from rest is normal. Does it continue in flight?

Blade 550X, T-Rex 450 Pro FBL

The heli flies perfect for 20-30 sec, then this occur....
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OK, how about engine tuning? Could it be going lean? Have you checked all the fuel lines for holes or tears?

Once it starts shaking, land and touch the backplate of the engine. Is it so hot you can't touch it?

Blade 550X, T-Rex 450 Pro FBL

New Dampers? Sound like they're chewed up.

thrust bearing in the blade holder the wrong way round???????

Remove the dampeners and lubricate them with a silicone based lubricant, then re-install. My first Freya wobbled like that when I flew it for the first time - lubed the dampeners and it disappeared immediately.

-Darren

1700 sounds low to fly at.
And to high to hover at..

/Fredrik
'Hm now I just have to find out where to connect the GV1 sensor to the Jazz80 ESC.

Hepp

Check your cyclic servos. I had a friend who's servo was bad. It wobbled like yours does. He changed servo, and the wobbling went away.

I mean, it is not rocket science we are dealing with here. If it wobbles it is fixable. Something is either bent or damaged, it is as simple as that. You just have to eliminate every possibility.

I run 1550 at hovering with CX dampeners, no wobbling. I had wobbling when I first put the CX dampeners in, but after a few minutes the CX dampeners settled in nicely, and the wobbling was gone.

-Hinke

Ok, I will check it out. Thanks for the help.

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