vibe help

[nick.m]

well as it was a sunny afternoon here i got of work early and raced to the field with my n5c in hand  got about 8 tanks on it now so decided to start tuning the motor a little as it was running quiet rich (redline 56) got it to where i thought it was running good and the backplate was still cool after a tank full but noticed with a 1750 headspeed  the skids were shaking a bit ,,idle 1 at 1850 and idle 2 at 1950 they were fine,,is it a case of trying to tune it out,,on a plus note the heli is flying awesome  and im absolutly loving it 

[Kevin Dalrymple]

You can raise the head speed in normal mode to 1760 or so and see if it goes a way. Did you lube the head dampeners? If not lube them and check how tight the head is. I bet living the head spindle will do the trick. I use a light amount of Boto lube to help with the break in of the dampeners.

[flyalan]

What FBL unit are you running?  You might need to look at your head gains. Depending on the FBL unit you may be able to adjust aileron and elevator gains separately.  Most likely you are just getting some aileron bobble at the lower headspeeds.  Also look at the head itself.  Any play in the head axle? Tight is good but a tight spindle and head will be more prone to bobble at low head speeds.
With the Helicommand on the E7 I get the same thing below 1700.  Not an issue since I fly at 1850.  You will find the N5C will like the higher headpseed anyway.

Alan

[Kevin Feil]

N5c Loves 2150 rpm. Definitely need to ramp it up like the guys have suggested. Good luck! congrats on the Flights!

Kevin

[Ross Lawton]

Hi Nick,

Definitely agree, the N5C loves 2150Rpm but try increasing the lower headspeed slightly.

The dampers will also take a few flights to bed in, i usually grease them up with a little silicone grease to allow the spindle to 'float' better.

Let us know how you go,

Cheers,
Ross

[nick.m]

thx for the replys guys ,,the head is tight but nothing was overtightened,,the dampers were greased with lithium grease..im using a skookum sk540 fbl unit and yes it has seperate gains for aileron and elevator
so ill try having a play and putting some different settings on the bank switching,, i didnt want to ramp the head speed up much more as im only a beginner really and at 1850 it more than lively enough for me,,
just seemed a bit wierd it was all ok untill i started to tune the motor..hopefully if we have decent enough weather this weekend ill get it sorted

[nick.m]

just wondering if any 1 has any more ideas as i cant seem to stop these dam shakes my heli has,,anything below 2000 rpm and its shaking ,,the lower the head speed the worse it seems to be or should i just forget about it

[flyalan]

It has been my experience that with harder dampening you must run higher headspeeds on most FBL units OR lower you head gains.
On the Helicommand on the E5 I wanted to run 2250. I had to drop the head gain drastically to do that. I ended up using 0.75mm shims instead of 1mm in the head. That's is all it took. I can now run hey head gain at 88 on the HC and run 2250. 

Cheers
Alan

[Kevin Dalrymple]

I would check the head shims. I had to change mine this year when I went back to the 750. Half mil per side is all it took.

I would also check the cyclic servos. I had one go bad and the Heli seemed to want to shake it self apart the more I tried to fly it.

[nick.m]

alan are you talking about the shim between the damper and the blade grip and if so is there a synergy part for the replacement or will any shim the right size be ok

[flyalan]

The part number for the 0.75mm is 106-802 and the 0.5mm are 106-801.
I keep all three sizes on hand (0.5, 0.75 and 1mm).  Comes in handy when try to tweak the dampening.


Cheers
Alan

[Jerry Kovar]

Also, double check ALL of your bearings.   I have found that some will go bad over time.  I "notched up bearing" will reek havoc on a FBL heli.   I have had them go from being perfect to a wobbling mess over one bad main shaft bearing...



Just food for thought..

[nick.m]

well ive checked all the bearings and they all seem fine,,after all heli has only about 25 flights on it and nothing hard,,i will get some shims and try that next as the head does seem rock solid with no give anywhere

[flyalan]

My money is on the head.  I bet you a flybar that using slightly thinner shims will take care of the vibes
I think I still have one of those lying around..Lol...


Cheers
Alan

[Kevin Dalrymple]

+1 on what Alan said.