RunRyder - Opinions Wanted... Vibration issue

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e-JR Voyager E > Opinions Wanted... Vibration issue

Stack
Veteran
Location: Bethlehem, PA

Hey guys, bad heli day for me. First thing this morning my Trex swash seized and down she went. I went to my backup VE and had more bad luck..

Out of the blue I got a nasty vibe on spool down. Bad enough to create the dreaded funky chicken dance.

I thought maybe I had a balance issue, re-did everything. Same problem. Replaced main shaft to no avail. So then I actually decided to try to troubleshoot

With no blades or even a flybar, the head will wobble at a specific, low rpm . The wobble goes away if the heli is picked up off of the ground. I started poking around and noticed that my main gear has a wobble and I have a feeling it is causing the problem. Everything else checks out. I also noticed that the main gear has a little bit of vertical play in it as well.

Just curious if you think I am on the right track here.

05-08-2006 Over year old.

helijunky
Senior Heliman
Location: s elgin il

check the main shaft bearings blade spindle shaft possibly is bent.i dont know what power system you are using but maybe rpm is slow for some reason.also recheck blade pitch and throttle curve with blades on.i hope this helps iused to have bad wobbles but now heli flys great.

05-08-2006 Over year old.

Stack
Veteran
Location: Bethlehem, PA

Thanks Heli..

Bearings could be suspect.

Spindle is straight. On brushless and it's definitely not a headspeed issue. Just at VERY low RPMs on spooldown I get the shakes. In the air I had a high frequency tail vibe so something is out of whack.

Blades are balanced (440 Carbons), pitch and throttle curves are good. This happens with the blades off so it is definitely something in the drivetrain.

05-08-2006 Over year old.

helijunky
Senior Heliman
Location: s elgin il

maybe tail blade shaft or holders. i know this might sound stupid but maybe some of the frame screws are loose?iam tring to help but seem to be failing.

05-08-2006 Over year old.

Stack
Veteran
Location: Bethlehem, PA

Hey Heli.... Ill check the screws later. I am still leaning towards the bearing!

I appreciate all of your input. Thank you!!!

05-08-2006 Over year old.

melvonnar
Heliman
Location: Clearwater Flordia

if blades are to loose on holders; it could cause a dance on spool up or spool down
I have mine pretty tight

05-15-2006 Over year old.

Stack
Veteran
Location: Bethlehem, PA

Hey guys, thanks for the input.

Again, without ANYTHING installed (no blades, no flybar, no mixing arms, no pushrods) I get a defined wobble @ about 300-500 rpm. Below that things are fine and above that things are fine as well.

So, there are only 5 things that can cause this (from what i can tell). In order: the motor, the gears, the main shaft, the head block, or the bearings).

I replaced both gears, the main shaft (with a hardened KSC version), and all bearings (with KSC). Spooled up without the head block and still get that vibe in that specific rpm range.

FYI: Tail boom removed so I have no interaction with the tail now. Gears replaced and mesh is correct.

I did manage to tame down the violent chicken dance (I had made a dumb mistake and didnt check the alignment of the head against the mixing arms when I took it apart) but that vibe still there and is just enough to bug me. I read elsewhere that this is normal ... but is it?

Anyway... I think I am back to being able to fly it again but I still want to fish out the culprit that is producing that vibe if possible.

05-15-2006 Over year old.

RC_Hobbies
Heliman
Location: Canada

Vibration Issue

Hi Stack,

With everything removed, your VE should not vibrate at all. In your case I can see 3 possibilities:

1) Damage/cracks in the head block
2) Damage/cracks in the heli frame
3) Lose Ball Bearings (as you said)

05-17-2006 Over year old.

Stack
Veteran
Location: Bethlehem, PA

Well... I think I have it figured out (I think!). Very minor bend in all 3 of my main shafts, just above the bolt hole. Must be from the original wobble issue that I created by having my head at less than 90 to the mixing arms. When I say minor bend, I mean minor. But just enough to cause an issue. Anyway.. 2 more main shafts on the way.

I tend to overlook the simple things sometimes.

05-20-2006 Over year old.

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e-JR Voyager E > Opinions Wanted... Vibration issue

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