High Frequency Vibration

[R0t0R]

Been putting a few flights on the 200 now that everything is back together and even just took it to the local hobby shop to have a local kid that works there and is sponsored by Thunder Tiger give it a flight. He liked it but pointed out what I already suspected. While watching him fly my 200 I could really see a high freq. vibration in the tail. It is making a noise almost like a gas powered motor when it comes up to speed and starts to vibrate.

Everything is tight on the tail, tail blades balance, belt is about right on tension and not twisted. Guess like some of the rest of you, the stock tail is just too flexible. Looking for a MicroHeli tail to order now to see if that helps. Will order some more SD tail drive shafts to have the option to go back to SD too now that I have the tail clearance issue solved.

Any other suggestions besides the doubling up of the CF tail plates on the stock tail assembly or spending the bucks on the MH tail?

[jimgrant]

R0t0R, make sure the tail spindle bearings are not loose in the gf frames, and the tail shaft isnt slightly bent... spool it it up slow, and look at the threaded end with the nut on. If the bearings are loose, a spot of ca , or epoxy round the outside of the bearing will fix that..I found all my tail boxes to be like this, 2 on helis, and a new spare in the stores..

[questionmark]

Can't share much really other than I got to HI Freq. vib too but not allways and it is a mystery for me.... I used to have an SD converted to belt. With the SD I also happen to got those vibrations, seeing sometimes the the tail fin vibrating up to the point the tip of the fin would double. But no special noise. While asking about the belt to convert to it, I was told about those vib. vs the SD but strangely when I converted I barely had no vibration, I just mean I did not see tail find vibrating and doubling ( not sure if I'm clear in the explanation) and this with stock tail even on CF boom. Then those came back again. I guess results of crash... At one point changed everything that was last week or so, main shaft, tail shaft and also CF boom pointed as a source of VIB...at this point I did not have any vib (all stock stuff except CF boom) but wanted to correct my tail really slowly drifting and though maybe some vib was the problem as suggested to me.... so I removed the CF boom I did not crash at all since and replaced by the alumin. one keeping all the rest (stock tail box, shaft etc) and back again the vibration with tail fin doubling... What surprised me is that I did not crash at all and ovbiously somethign was not perfectly done when changing the boom but what???... I'm believe the belt was not twisted, I've try different belt tension....nogo...In the mean time I received the MH tail box, and all other component...and since changing to it no vibration. This tells me it is not necesarely the MH stuff that helps..but maybe makes it better...

I just try to say here there is some mystery that I like to understand, surely crash would give vibration, a slight bend shaft wich require a minimum blade tracking would give the problem I guess...but again changing the main shaft including tail shaft and vib came in...and without a crash...

So if anyone as some kind of idea, a checklist or something like that, it would be great. Also when puting the belt I'm really carefull I don't twist it... well only a quarter turn to the right for the propoer position...but you can make mistake...Is it possible to figure out if the belt is twisted inside the boom? When I put in place the belt I use a soldering thread to pass it inside the boom and makse sure it does not turn when pass it in the boom

I checked the right from the begining the tail bearing and also CA them just in case, I've seen post talking about this problem and allways checked this..

Thanks all for tips and idea

[R0t0R]

Just took another look at the tail. I had CA'd the bearings in the tail when I first got it after reading on here about that issue and they are still solid. Did notice that there is some play with the tail rotor shaft in the bearings, but when I spin it up, the nut on the end looks very solid. Did notice that the belt moves around on the gear on the tail rotor shaft. The end of the "bat wing" vertical fin buzzes at a high frequency. Thinking that the MH tail assembly would help being more solid and having belt guide pulleys incorporated in the setup.

Anyone else try the stock belt tail assembly, then go to the MH unit that can tell me if they saw a difference? Kind of waiting for HeliDirect to get them back in stock so I can order a 5150 motor at the same time. The only place I saw today that had the MH tail in stock was HeliHobby.

[Buzzkill]

Stock tail is ok to start with but wears quickly. MH tails are nice and smooth if everything is balanced and not bent and they don't wear like the CF stock ones.

[jrhf]

For me, it has always been caused by one of the following three factors:

1. Main grip screw bent. Vibration in entire frame upon high throttle, and a few seconds prior head stopping, while there is absolutely no vibration when you remove main blades, is a typical sign. To check, no other chance but to remove the screw and check visually.
2. Tail shaft bent. Checked the usual way...
3. Assymetry of tail gear semi-diameter. This could be clearly visible if you spin it up on low throttle and side watch to check if the belt isnt going up/down... Something else is belt sliding sliding left-right over the gear, which does not seem harm anything, as long as it does not happen with a single tail revolution.

Regards,

Jan

[R0t0R]

Thanks, that's what I was looking for. Still think I will wait until HeliDirect has them in stock so I can get the upgrade motor. Hard to beat $22 for a stronger motor. Living in the thin air of Denver, the extra power will be nice when I start doing aerobatics, (at least the intentional kind!) as I have already noticed some bogging even with a 0-85-90-95-100 throttle curve in normal. Haven't tried idle up yet, but set it to 100 across the board per LittleMan's suggestion.

[Jetleaf]

I would check the bearings for smoothness. I've had brand new bearing that felt like they had fine grain sand in them and others that were smooth as glass. Also make sure the belt isn't rubbing against the inside of the tailbox right where the belt exits the boom

[CHOPPERTECH]

I don't know if this might help. I am a harley tech. and we use a toothed belt and pulley on harleys and most custom bikes. If the belts get stretched the teeth do not mesh well with the grooves in the pulleys and cause vibration & noise, also if the valleys and peaks on the pulley get worn they can cause problems. also check to see if the edges of the belts are wearing this can cause a lot of problems on the full size counterparts. These are much larger components but i would think that they might show the same symptoms as the much smaller gaui parts.
Get your loupes out and really look closely at the pulley and belt valley and peaks.
Les

[R0t0R]

Thanks for the suggestions of things to check. I had forgotten about checking the smoothness of the bearings. They seem smooth and there is no wear on the belt, so it isn't rubbing on the boom.

Choppertech! I had never heard of that, but definitely wanted to check it out as a cause! The teeth on the belt look like new and are engaged on the main gear and tail rotor pulley.

Only thing I can figure is that there is too much play in the stock tail assembly and the CF side plates allow it to vibrate too much the main rotor runs real smooth and the blade tracking is right on.

I'll keep checking things and if anyone else has suggestions, I'll give them a shot. Really like this little heli and would like to get it smoothed out.

[Jetleaf]

I just thought about this, make sure the boom is perpendicular to the main shaft.

[R0t0R]

Well, HeliDirect just got the MH tail back in stock, so ordered one and a 5150 Z-Power motor to put in later! Just have to get rid of that vibration before it causes wear in other components. Hope this does the trick. Took the stock tail apart today and noticed there is a lot of room for the tail rotor dirve shaft to move around inside the flange bearings. Tried the side plates from my SD tail and they are the same way. Will also be looking for some CF tubing to make a tail rotor pitch linkage like others of you have done and get rid of the flexy stock wire. (Getting tail wag when I throw the tail around, probably from the linkage flexing!) What size tubing are you guys using to make the linkage? (Sorry, can't find the thread!)

Will let everyone know what kind of difference the MH tail makes when I get it put on!

[small.planes]

Look here for CF tubing link:

http://www.helifreak.com/showthread.php?p=738454&highlight=pultrusion#post738454

hth
Dave