Bobble

[copenhagen]

OK, so I don't even know if this is actually a problem being as I have never actually gotten to fly helicopters with anybody besides myself.

I have a small bobble when I hover- it seems to clear up during directional flight.  I don't think it is as pronounced during inverted hovers, but it is hard to say.  I do not know if this is normal or if there is something wrong.  I honestly feel like my helicopter has done this since day one, but it is hard to say.  Yes I have crashed before, however, I replaced torque tube, main shaft, feathering spindle, etc.  I checked the main shaft bearings and they did not feel notchy to me.  I did replace one tail box bearing but I don't see the tail being the cause of this bobble.  I do not know if the gain settings in the V-Bar could have an effect on this either.

Open to suggestions- lay them on me.

[flyalan]

Yes the gain may need to be lowered just a bit.  Is it an aileron bobble?  Try lowering the head gain 5 clicks at a time and see if that helps. You can also try using thinner shims on the head.  This will soften up the dampening which in turn will allow higher head gains.

Cheers

Alan

[copenhagen]

I don't know that it is just an aileron bobble- it seems like it is more of a total bobble.  An exaggerated way to describe the bobble would be if you imagine what happens to a spinning top as it slows down.  When you look at the tail during a hover the tail drifts up and down for maybe a total of one inch of travel.  Of course you do not see so much left and right, however, due to the geometry of the tail and the bobble, I wouldn't expect that to be so noticeable.

Where can I get smaller shims?

I am running 80 on main rotor gain and 85 on my tail.

[Chris Sexton]

I actually chased a hover only wobble on my n5c tt that I fixed by loosening the blade tension in the grips. Mine are still snug and autos seem ok, but I had them way too tight.

sent from my Verizon Samsung Galaxy Note 2

[flyalan]

Also what head speed are you running?  If you are trying to run a low head speed you may need to lower your gain or use thinner shims.

You can try the 0.75mm shims.  part number 106-802

Cheers

Alan

[Jon Mills]

+1 on the Grip bolt torque also on the N5C for me, weird thing happen when its too tight especially on the tail.

[copenhagen]

I am running really close to 2380 give or take a couple RPM.  I have a 13T pinion, 1100kv motor, and am using 6S 35C batteries.

How tight on the main grips?  I am doing three fingers tight with both hands.  What about the tail?  I make the tail grips just tight enough so the tail blades don't fall under their own weight.

I will order some of those smaller shims.  Thank you for the tip.

[flyalan]

That head speed should not be the cause then. Again. Try lowering your head gain and see if it gets better.

Sent from my SM-N900V using Tapatalk

[copenhagen]

I'll give that a try- how many points at a time should I lower it? (I'm at 80 right now)

[flyalan]

I would drop it to 75 and see if that makes a difference.

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[Kevin Feil]

+1 on the Gains, as well as the Blade Tightness, if the blades are to tight you will surely end up with a (Lead/Lag) issue which will cause the wobble you are indicating. It is one of those trial and error things when it comes to the proper torque, (what is the proper torque?) I usually tighten mine down to the point were I can cup the leading edge of the blade with 2 fingers and without a lot of effort pull it back to the stowed position.. Now if you obviously do blade stop autos and blade scrapes, tighten them down a bit more. Also, when you installed your Spindle Shaft, did you lube the shaft? I have seen this before where the spindle will bind in the dampeners depending on the Fit. Like Mentioned before, the Head speed is fine. Also the last thing, I read we're you crashed before, not knowing the extent of the crash, how are the Dampeners? Are the older?  I would also recommend chancing the dampeners for a New Set if you haven't done so already. This is another common thing in Full Scale helicopters that In cur a wobble. Keep us posted, I would recommend you do one step at a time and test for results, if you do everything at once you will never know what the true fix was and this intel will surely help others if they experience an issue such as this.. Good luck brother...

K

[copenhagen]

Kevin,

Yes, I put a little grease on the spindle when I installed it.  mjburberry has recommended that I try going through the head setup again, so I'll give that a shot too.  I am going to try loosening the blades a bit first as that is the easiest thing to try first.

The crash- well I broke both frames in half and did not break the main blades (I have since installed new ones chasing down this bobble)- what happened was the esc wire rubbed through the heat shrink on the frame, shorted, smelted the solder and voila- no power.

[Kevin Feil]

You did replace the main shaft right? Keep us posted Brother

K

[copenhagen]

Oh yes.  New Main Shaft.

[Rodney Kirstine]

That's crazy that the blades survived a crash that destroyed the frame!  It never ceases to amaze me how different each crash is and how some parts survive when others get mangled.  My luck is that any type of crash, no  matter how "gentle" always destroys the blades and they're usually brand new ones on their first or second flight.