shaft drive on page 18, please help :)

[benzmaster]

Hello, I'm trying to insert the shaft drive (torque tube) into the tail boom...it's a little bit hard to do.
Should I apply CA on the shaft to hold the bearing ? It seams that even with the CA it's very hard to put it inside the tail boom because of the plastic part around the bearing. you need to force and the CA will not hold it enough I think. Is there a better way to do that ?
thx

[Mercuriell]

You need to locate your shaft bearing off centre - putting it dead centre can lead to resonance problems. You need to fix the bearing in place ideally using Loctite bearing retainer or blue Loctite - if you don't have these you shouldn't be building your heli but you could use CA at a pinch but careful not to get any onto the bearing surfaces. Once this has set and the bearing is firm on the TT shaft put the rubber mounting washer over it and then lubricate it with some washing up liquid. Run some water down the inside of the tail boom and you should find with gentle pressure it should slip down - when you need to take it out running water down again lubes it all up !!

[Tintin]

Originally Posted by Mercuriell

putting it dead centre can lead to resonance problems.

Any position will be just about equally prone to result in resonance. Only difference is that with it dead centre the frequency will be the same for both halves. If it's off centre the longer part wil have a hight res frequency than the shorter so you will have 2 rpms that can create problems rather than only 1.

[Mercuriell]

If you play the guitar you'll know that you can produce harmonics from a sounding string by damping the string exactly half way with your finger - trying this off centre will dampen the resonance - same goes for the TT

[benzmaster]

Okay, I play the guitar so I've understood thx for the washing up liquid tip !
so i'm gonna place it as they say in the documentation... about 5cm near the center

[Tintin]

I don't know if it's your definition of resonance that is off, but I can absolutely guarantee you that you can get resonance at any position.

On a guitar string you will get a tone no matter if you dampen the string half way, 3rd or whereever you put your finger
You will not get tones only each time you dampen the string at half the length. If you start at the top of the neck with your fingers, hit the string and then slide your finger down the neck you will get a tone that increases evenly, not in steps for each time you hit a half length mark.

Note, I do not say to put the bearing at the middle. If both parts vibrate at the same time it'll probably be worse than if the front and aft parts vibrate at different frequencies. But each part of the shaft will have a set of resonance frequencies no matter where the bearings are placed.

The string will vibrate at a different frequency for each length creating a different tone for each length. It will always vibrate at it's first eigenfrequency if you hit it no matter if it's one meter, 0.50 meter or 0.31456 meter.

I guess what you call harmonics is when the frequencies are multiples of eachother which is what you get from dividing the shaft or string exactly in 2.

If you divide it in 2 then you will get the first and 2nd frequency.
If you divide one of these halves in 2 again you will get the 3rd and so on.

The string or shaft can vibrate no matter what length, the length only determines at what frequency it will vibrate not, not whether it will vibrate or not.

[benzmaster]

okay, anyway I placed it just like they say on the doc. but it was hard to insert even with washing up liquid. I hope it's not going to rust with the water and washing up liquid still inside... do you think it could happen ?

[Mercuriell]

Originally Posted by benzmaster

okay, anyway I placed it just like they say on the doc. but it was hard to insert even with washing up liquid. I hope it's not going to rust with the water and washing up liquid still inside... do you think it could happen ?

You're supposed to empty the water out before mounting the tail boom on And no I don't think the bearing will rust as it's greased and very short exposure - I've had two enforced TT disassemblies since using this method and haven't had a problem!

I guess it's all a matter of damping - if you just put your finger on an instrument string and pluck it you will get only a perfunctory thwug - if you fix it to the fret board you will get resonance and a tone - the rubber bearing mount is more akin to a damping finger than being fretted down hard onto the fretboard. If you put your finger exactly half way though - you will produce two standing waves (resonance) of equal frequency one octave above the length of the whole string and this I believe is what happened in early Align trials of the 600N hence their advice to mount the bearing off centre.

[Tintin]

Yes probably. My point is only that you can get that standing wave no matter what. It will just happen at different frequencies. 1 for the shorter part an another frequency for the longer instead of one frequency that will create a standing wave simultaneously for both parts.

However if it's placed at exactly 1 3rd you can also get simultaneous standing waves for both the short and the long part when you hit the 1st eigenfrequency of the short part which will equal the 2nd eigenfrequency of the long part....and so on.

[HeliSat]

The method I found easiest was using the washing up liquid (no water needed), then push the bearing holder down the tube using the protective case that the TT came in.

[benzmaster]

that a good idea ! thx

[dennis@deetee]

Tri-Flow works very well to.

........Dennis

[erniefritz]

Dennis , i'm with you , i used tri-flow on my TT install , worked like a charm...

[Mercuriell]

Originally Posted by erniefritz

Dennis , i'm with you , i used tri-flow on my TT install , worked like a charm...

Have you had cause to try removing yet ? The WD40 I used 1st time got it in OK but was a PIA to remove it when I needed a boom change (didn't like the colour ) whereas I found with the washing up liquid it regained its slip when a bit of water was trickled down weeks later.

[dennis@deetee]

Well, have not had a reason to replace it yet simply because don't get much flying in.

But, I would think that if I did, it would be damaged and it don't matter anyway. I would just jank it out any way I could. Probably the boom would be demaged as well and the whole thing goes in the trash.

.........Dennis

[roinides]

One simple question Does the carbon boom i have from the 600E is ok for the nitro?

[benzmaster]

yes

[roinides]

nice!!!