Tail vibes got you down, try this!

[Cujo22]

I swapped out the flanged bearings, didn't work.
Adjusted gear mesh perfectly, no change.
Tried the Walkera pitch slider, nope.

Dynamically balanced the tail blades, BINGO!

Take your main blades off and spin up the heli.
Listen to the sound of the tail, it should sound like spinning blades not a coffee grinder.
Add a small (5mm) square piece of cellophane tape over the leading edge of one blade and re-spool. No change? Take the tape off and switch it to the other blade. Better? Tweek until vibes are gone.

At 20000 rpm's, vibes from the smallest imbalance will eat bearings and shake this thing apart.

Worked for me, no resonance, no vibes. YMMV, good luck.



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[Hydropwnic]

It cant be that easy can it?

Will try tomorrow..i am sick of the coffee grinder sound!

[Cujo22]

Originally Posted by Hydropwnic

It cant be that easy can it?

Will try tomorrow..i am sick of the coffee grinder sound!

I think there are a variety of issues, this seemed to be mine. I just put a battery through it and it was a different bird.


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[DoubleCH]

I tried that, too, but that was before I balanced my A/B/C gears so the tail rotor was still not perfect. I was starting to spin-balance just the tail rotor assembly by removing just C gear, use a desk fan to blow at tail rotor and turn tail servo to adjust tail pitch to get max RPM and then check for vibration. This way I was able to better balance just the tail rotor assembly without gear mesh. It's a tedious task and I was surprised how little tape makes a huge difference at even just fraction of actual working RPM. it was time to go fly this afternoon so I didn't get a perfect balance before putting back everything together. Now that I have A/B/C gears pretty much balanced, I'll try rebalance just the tail rotor assembly first, and then hook up to tail drivetrain and use main motor to spin-balance the whole drivetrain. I don't know, I have a feeling that when under load the TT is out of balance or springing like a guitar string. I think I'll try carbon TT some day but I am in fear that it won't hold at the D-cut. I don't mind it breaks on crash but I don't want the D-cut fail under normal stress.

[Skinny_j]

I think 100% of the problems with this heli stem from the vibrations on spoolup. That high of a frequeency resonance can play hell on all parts of the heli.I have broken 2 pitch slider pins just spooling up. My resonance seems to be across a broader rpm range than everyone elses. Mine will start vibrating during flight. Seems like there isnt a single fix thst will fix them all. different stuff works for different people. nobody seems to know exactly where it is coming from. I just put some really thick grease in my boom and a piece of .002 shim stock in there to hopefully get rid of the vibes that seem to be destroying my heli. And horizon says this is normal. Its like buying a new car and having the dealer tell you its normal for it to backfire til it warms up. Granted hh has sent me the parts tgat keep failing but the ones they send me fail just as fast. .I wouldnt have any of these problems if tge damn thing would just spool up smoothe!

[Hydropwnic]

Originally Posted by Skinny_j

I think 100% of the problems with this heli stem from the vibrations on spoolup. That high of a frequeency resonance can play hell on all parts of the heli.I have broken 2 pitch slider pins just spooling up. My resonance seems to be across a broader rpm range than everyone elses. Mine will start vibrating during flight. Seems like there isnt a single fix thst will fix them all. different stuff works for different people. nobody seems to know exactly where it is coming from. I just put some really thick grease in my boom and a piece of .002 shim stock in there to hopefully get rid of the vibes that seem to be destroying my heli. And horizon says this is normal. Its like buying a new car and having the dealer tell you its normal for it to backfire til it warms up. Granted hh has sent me the parts tgat keep failing but the ones they send me fail just as fast. .I wouldnt have any of these problems if tge damn thing would just spool up smoothe!

If you are vibrating during flight are you 100% sure your C gear isnt spinning on the torque tube?

I had a crash and stripped the A gear. Replaced it with the metal one. I thought the C gear was fine (spun the main rotor, and tail rotor spun when holding the tail with a little bit of force). However, my first flight i got it in the air and the tail shakes didnt stop like they normally do. I tried holding the tail blades with a little more force and spun the main rotor and sure enough the C gear was rounded out a little bit and spinning in the TT. Replaced C gear and all was good (until my next part failure 2 flights later).

Hope you figure it out, good luck.

[Skinny_j]

Yeah it could have been that, I replaced the c gear while I had it apart. Didnt vibe this time, but still did on spoolup but not as bad. My cad pin broke on my second pack but I was able to get it down. One of my flange bearings seized up and melted the tail case tho. Arrrrrgh. I just hope I can be patient enough for when upgrades start rolling out. I think its gonna be a shelf queen til then.

[sertav]

Originally Posted by DoubleCH

I tried that, too, but that was before I balanced my A/B/C gears so the tail rotor was still not perfect. I was starting to spin-balance just the tail rotor assembly by removing just C gear, use a desk fan to blow at tail rotor and turn tail servo to adjust tail pitch to get max RPM and then check for vibration. This way I was able to better balance just the tail rotor assembly without gear mesh. It's a tedious task and I was surprised how little tape makes a huge difference at even just fraction of actual working RPM. it was time to go fly this afternoon so I didn't get a perfect balance before putting back everything together. Now that I have A/B/C gears pretty much balanced, I'll try rebalance just the tail rotor assembly first, and then hook up to tail drivetrain and use main motor to spin-balance the whole drivetrain. I don't know, I have a feeling that when under load the TT is out of balance or springing like a guitar string. I think I'll try carbon TT some day but I am in fear that it won't hold at the D-cut. I don't mind it breaks on crash but I don't want the D-cut fail under normal stress.

How did you "balance" those tiny little gears?

[sertav]

Originally Posted by Skinny_j

Yeah it could have been that, I replaced the c gear while I had it apart. Didnt vibe this time, but still did on spoolup but not as bad. My cad pin broke on my second pack but I was able to get it down. One of my flange bearings seized up and melted the tail case tho. Arrrrrgh. I just hope I can be patient enough for when upgrades start rolling out. I think its gonna be a shelf queen til then.

Call HH customer service and ask for an RMA number. Return it for a refund. They did it for me. No sense having a heli just sitting and gathering dust. Heck, who knows...maybe by the time you get around to buying another one, HH will have made some changes/upgrades/V2, whatever...

[litehawkdown]

Saw a guy post a vid where he added another tail pitch rod guide to stop the pitch rod from vibrating. It was something I was going to look into when I got mine. Seems to be sloppy back there. http://www.helifreak.com/showthread.php?t=434139

[DoubleCH]

Originally Posted by sertav

How did you "balance" those tiny little gears?

Sorry I should've been more descriptive. When I said "balance", I meant mechanical-wise (turning true) not weight-wise (which would be anal to do).

A gear:
I found out when unscrewed the gear is very sloppy on the mainshaft. And because the gear is screwed onto the shaft on one side only it'll pull the gear off center. I coated the inside of the gear with CA. Filed excess off carefully. Test fit and file again if necessary. Screw the gear in place without main gear or B gear. Rotate main rotor and check balance. File again and/or add more CA. It's a tedious job but I eventually got it right it's worth it IMO becuase it also gives A gear the most clearance from the front servo. If you do work on A gear, make sure to recheck screw tightness after each initial flights. CA may come off and loosen the screw.

B gear:
Mine was loose on the TT. This one instead of coating the inside of the gear I coat the TT end with CA. Mostly on the D-flat which is the cause of the slop. Test fit B gear and file CA off if necessary. Insert TT reversed on boom temporarily to make sure it turns true before installing it.

C gear:
Mine wobbles and also tilts to one side (away from the D-flat IIRC). I just CA it and press the gear towards the D-flat side which has the most slop. Test spin in installed position by rotating main rotor.

My D gear is still nice and tight and turning true on the shaft so no need to work on it.

[sertav]

Originally Posted by DoubleCH

A gear:
I found out when unscrewed the gear is very sloppy on the mainshaft. And because the gear is screwed onto the shaft on one side only it'll pull the gear off center. I coated the inside of the gear with CA. Filed excess off carefully. Test fit and file again if necessary. Screw the gear in place without main gear or B gear. Rotate main rotor and check balance. File again and/or add more CA. It's a tedious job but I eventually got it right it's worth it IMO becuase it also gives A gear the most clearance from the front servo. If you do work on A gear, make sure to recheck screw tightness after each initial flights. CA may come off and loosen the screw.

That's a lot of work when you can just get the metal A gear. It fits perfectly and has screws on both sides.

[DoubleCH]

That is if I can get one. OTOH, I love to tinker with whatever I have on-hand.

[Liduno]

Originally Posted by litehawkdown

Saw a guy post a vid where he added another tail pitch rod guide to stop the pitch rod from vibrating. It was something I was going to look into when I got mine. Seems to be sloppy back there. http://www.helifreak.com/showthread.php?t=434139

I put a slight bow in my servo push arm, it pushes the link onto the ball and it puts a small amount of pressure against the guide.

Before I did this the push rod was very loose and bounced around.

[litehawkdown]

Originally Posted by DoubleCH

That is if I can get one. OTOH, I love to tinker with whatever I have on-hand.

Me too. It is more hobby to me that way then just slapping hop ups on a heli.