250 Tail Vibration

rseegers · 08-03-2012, 05:40 AM

Last week I tried to squeeze one too many flights out of an old lipo and I had to drop my 250 on grass. This resulted in a tiny chip on a tail blade and my tail vibration came back.

YouTube

When had this before I ended up buying a lot of Align tail parts but never worked out the cause so bought a new HK kit in the end. I am now in the same situation again. The first thing I tried was a new belt, bearings for the tail box and a new tail shaft pulley. I also sanded down the tail blades and swapped out the blade screws in case they were bent.
I span it up indoors and the tail shook and damaged a new bearing I’d just installed (I didn’t loctite the bearing in, but I don’t see how this would make much difference.).

Any suggestions? Next thing I'll try is new tail grips/hub and new blades, but I don’t think that’s where the problem is.

Also, is it just me or does mixing clone and align pulleys never work? i.e. if you have a clone gear pulley you can't have an align tail shaft and visa versa

JoeW · 08-03-2012, 06:43 AM

Actually the grip/hub is the next logical place. The bearings in the tail grips are very deliacte and could easily be separated after a knock.

jonbailie · 08-03-2012, 09:17 AM

Also, check the tail spindle shaft. If its bent, it could cause this type of vibration.

Sent from my iPad using Tapatalk HD

rseegers · 08-04-2012, 09:24 PM

I've narrowed it down to the tail hub/grips. It's not damaged grip bearings as I swapped out the tail grips for barely used HK ones.

I'd be happy enough to order the Align tail grips if I believed it would fix this, but I've had hundred of trouble free flights out of the original copterx tail grips. Instead I've ordered gram scales as maybe it's a balance problem.. although it I don't understand how that could be intermittent.

terrabit · 08-05-2012, 02:14 AM

Your tail blades are loose. They should not drop under their own weight. It's also risky spooling up with your mains like that. If they're not outstretched you can get a boom strike with minimal cyclic or collective input. Might not be such a concern with a heli this size but I still wouldn't do it. Mains and tails should be outstretched and hold under their own weight if tipped to the side. Loose blades can also result tracking issues.

youturnjason · 08-05-2012, 03:23 AM

Do your tail grips have one or two bearings in them? If they are the old style grips with 2 bearings in each grip, the bearings go bad very easily. The newer weighted grips with 1 bearing seem to be alot better.

rseegers · 08-05-2012, 10:46 AM

Clone grips are single bearing and the bearings at least are durable. However, I just managed to shear off a screw in a tail hub by trying to reuse it which was stupid as I had spare bag of new screws.

Anyway, using my remaining spare hub, new screws and HK grips I've managed to reduce but not eliminate the vibration. I am not going to fly it like this as it causes too much wear and tear.

It's a bit of curse for my 250. Last time I think it was something to do with the belt/pulleys (when the video was taken) although they didn't look worn out. This time it appears to be poorly balanced blade grips, but if that were true why didn't it show up before?

08-03-2012, 06:43 AM	#2
JoeW Registered Users My HF Map location Join Date: Apr 2011 Location: Oakville, ON - CDN	Actually the grip/hub is the next logical place. The bearings in the tail grips are very deliacte and could easily be separated after a knock. __________________ TRex 250 DFC \| TRex 250 DFC (Scale) 2 @ TRex 450 DFC \| TRex 450 Pro 3G (Scale) TRex 550 DFC DX8 + Telemetery on all

08-03-2012, 09:17 AM	#3
jonbailie Registered Users Join Date: Sep 2011 Location: Savannah, Georgia	Also, check the tail spindle shaft. If its bent, it could cause this type of vibration. Sent from my iPad using Tapatalk HD __________________ // T-Rex 600EFL Pro 3GX // T-Rex 450 Pro V2 3GX // T-Rex 250 Pro DFC 3GX // // Walkera V120D02-S (x2) // Walkera V120D02 // Walkera Genius CP (x3) // // EFlite Blade MCPX (x2) // EFlite Blade 120SR // E-Sky Belt CPX // // WK2801 // Spektrum DX4e //

08-05-2012, 02:14 AM	#5
terrabit Registered Users Join Date: May 2007 Location: Seattle	Your tail blades are loose. They should not drop under their own weight. It's also risky spooling up with your mains like that. If they're not outstretched you can get a boom strike with minimal cyclic or collective input. Might not be such a concern with a heli this size but I still wouldn't do it. Mains and tails should be outstretched and hold under their own weight if tipped to the side. Loose blades can also result tracking issues. __________________ vbar T700E v2 DFC head, Pyro 700-45L, Jive 120HV, BLS451/BLS251, Edge 693/115 vbar CF Protos Scorp 3026-880kv, Ice lite 75, 9650/BLS251, SAB 430/KBDD 82

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08-04-2012, 09:24 PM	#4
rseegers Registered Users Thread Starter Join Date: Jun 2011 Location: Asia	I've narrowed it down to the tail hub/grips. It's not damaged grip bearings as I swapped out the tail grips for barely used HK ones. I'd be happy enough to order the Align tail grips if I believed it would fix this, but I've had hundred of trouble free flights out of the original copterx tail grips. Instead I've ordered gram scales as maybe it's a balance problem.. although it I don't understand how that could be intermittent.

08-05-2012, 03:23 AM	#6
youturnjason Registered Users Join Date: Apr 2012 Location: Melbourne, Australia	Do your tail grips have one or two bearings in them? If they are the old style grips with 2 bearings in each grip, the bearings go bad very easily. The newer weighted grips with 1 bearing seem to be alot better.

08-05-2012, 10:46 AM	#7
rseegers Registered Users Thread Starter Join Date: Jun 2011 Location: Asia	Clone grips are single bearing and the bearings at least are durable. However, I just managed to shear off a screw in a tail hub by trying to reuse it which was stupid as I had spare bag of new screws. Anyway, using my remaining spare hub, new screws and HK grips I've managed to reduce but not eliminate the vibration. I am not going to fly it like this as it causes too much wear and tear. It's a bit of curse for my 250. Last time I think it was something to do with the belt/pulleys (when the video was taken) although they didn't look worn out. This time it appears to be poorly balanced blade grips, but if that were true why didn't it show up before?