CarGuy7a

Ok I'll start by saying my last crash destroyed quite a few parts. So far I've replaced a feathering spindle, main rotor shaft, main rotor gear, tail boom, and blade grips. The blades didn't even get damaged to my suprise so I re used them (not sure if I should have done that or not but I didn't see any physical damage). Ok now here is where it gets interesting. I got everything back together and made adjustments to set it back to out of the box condition. I did get the Real Flight Sim so I could learn it and stop breaking parts which worked great. The first flight after the crash and new parts went absolutely perfect for the first lipo.

Now on the second lipo I lift off and I immediately noticed something was terribly wrong. I didn't do anything different between packs besides let the motors cool and all of the sudden it's got a wicked shimmy in it. It's not really a wobble it's more of a huge vibration. The blades are tracking near perfect and the swash is level. I did find that I hooked up the linkages on one side for the blade grips the wrong way so I fixed it and tried it again. It flew perfect until the pack wore halfway down and the vibration returned. So I got on here and read that if the servo rods were too short it could cause this symptom so I lengthened them each one full turn from stock, flew it again had the exact same thing happen, half the pack and vibration returned.

I cannot for the life of me figure out what is wrong. I know I have everything set correctly and can't understand why the first half of flight is smooth and vibration free and then all of the sudden it starts vibrating like crazy for the last half of the pack. I flew it a total of 4 packs today and got the same result on each pack.

I'm going to try some new blades tomorrow and see what results I get.

Any help or insight is greatly appreciated.

Dick T.

My Feedback: (243)

Since the vibration appears consistently on the second half of the pack, my guess is the problem may be:

1. Electrically/electronically related. Main motor and/or speed control may be stuttering at lower voltage or heat build up is creating a motor issue. Main motors are cheap, try a new one.
2. Mechanical.....gear mesh may be getting loose or the motor is shifting slightly, again due to heat.
3. Head speed is dropping and main blade lead/lag is changing. Blade holder bolts may be too tight or one is looser than the other allowing one blade to change position. Blades should pivot smoothly, easily and resistance should feel equal.

Since the blades stay in track and run smoothly the problem is in the power/gear train/rotor system.

All are pretty easy to try.

CarGuy7a

Speaking of Gear Mesh. Would too tight of a mesh cause this? Also how do you set the mesh? I set the mesh on my surface RC's with a piece of paper between the gears then tighten the motor down. Should I do the same with my heli?

Also would a wobbly rotor gear cause this? I dunno if it would since it only does it halfway through a pack. The original gear didn't wobble I don't think. It's not a huge wobble just a slight one and it is a brand new gear and shaft so I dunno. It's just really annoying.

Thanks for the response. I will try a new set of blades tomorrow just to see if it still does it.

PilotLight

My Feedback: (1)

Sounds to me like the higher headspeed during the first half of the battery is "masking" the vibration. Once the blades slow just a bit the vibration is at a frequency that shows up more. Try balancing the blades again. You can also run up the head without the blades attached and see if the flybar is causing the vibration. It could be bent, or it could be slid towards one paddle.

CarGuy7a

I think the fly bar is ok, that was one of the things I made sure was near perfect. I'm gonna go out here in a few minutes and mess with it a while. I may take it apart yet again and reset everything and start from scratch. I'm gonna try a different set of blades as well.

CarGuy7a

You know I just thought of something. Will incorrect pitch cause this. I mean different pitch on each blade, if they are not the same would it cause what problems I'm getting.

PilotLight

My Feedback: (1)

That is what causes tracking problems, but yes it could cause vibration too.

CarGuy7a

Ok I got it fixed. I installed a new blade set (solid plastic blades instead of the wood ones) what I also did was take off all the 4 short links and shortened them until they wouldn't go any further and then lengthened them all the same until the pivot on the blade was perfectly level when the flybar was level. After that I spooled it up and reset the blade tracking which only took about 1 turn on one of the upper short links. I also reset the servo linkages and got the swash level for like the 10th time LOL.

Vibration GONE YAYY!!! I ran one full pack through it and only got a slight vibration right before the power ramped off which I can live with, but it's nothing like before. It is 110% better than it was.

Now I may be able to actually go have fun with this thing.

Thanks Fellas