Please help, Logo 400 tail wag

[Primus]

Still trying to eliminate the wag. Lowered the TH at 90, no change, saw a bobbing in the head also when loading the disc.

Both gear mesh OK, belt tension ok.

Will try a new 18T pinion, had a 20T pinion in combination with a Hacker A12 1600kV

Ordered a new tail hub with grips, some hard dumpers and a true BLS251 for the tail

[Ricci]

Originally Posted by Primus

... and a true BLS251 for the tail

That's your "true" solution, you will see...

Bonne chance!

Ricci.

[Primus]

Tested today with 18T pinion. Is so smoth. The wag is still there.

On the Vbar event, everything on green, one raised vib.

Here is the spektrum analyser, in fligh measured, light aerobatics, landing included.

[galensk]

Hi,

Is this with the BLS-251 ?

Kurt

[Primus]

Hi Kurt

No not here yet, still using 9257. I have a new DS620 will try that tomorrow if wheather will be good.


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[Primus]

Changed the tail servo today with a DS620. More power on tail.

But.... yes, The WAG is still theeeeere !!!

Had a second vibration in flight analyser. 350 on tail with blades
Those 9 bucks Ebay bluetooth modules are just great!

Could a mising belt tooth do that?

[galensk]

hello,

imo your good on vibration level. So we have to look elsewhere.

your belt should indeed have ALL the tooth and the tension should be correct. Not to hard, not to lose.

next which ESC do you use and how is your throttle curve ? do you use governor or not ?

Kurt

[Primus]

Hi Kurt

Checked for belt tension but not for any missing tooth

Using CC ICE 75 fixed endpoints, no gov atm.
Th curves
Normal 0 60 70 90
IU1 95 flat
IU2 100 flat

Realy like the heli, set the vbar on the precise side and a litle bit more agility today.

Thanks for your help here


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[galensk]

Hi,

not familiar with the ice CC but I think you're OK there. If you don't use the governor it can't upset the tail.

some mor things you can check

teeth on the belt
teeth on maingear and tailgear
gyro gain in the vbar ( mine is a little lower than indicated )
horizontal play on the tailshaft???. It should not have any play, you can add the provided shims to eliminate play, at least if thats the case ...

bonne chance
Kurt

[Primus]

Hi again

Cheched both the maingear and tail. No damage. Not checked yet the main bearings and one way. Will do that tomorow morning.

Rebuild the tail again no axial play in the shaft or bent shaft.

Gain: about 75 in Normal and 65 in IU2 (80 indicated for Logo 400 in vbar software) In the last test with the DS620 felt that it needs more than 65 in IU2.

Thanks for your inputs. It helps me not to forget something :-) aaarghhh!

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[galensk]

no problem !
the bls-251 should make a difference also...
do you have the ebay source for the bt interface.... interesting to see the spectrum while flying
Kurt

[Primus]

Here ya go:

http://item.mobileweb.ebay.com/viewi...id=26047487538

I have four of them. Watch on HF for wiring. Connection on vbar control panel port, tx and sx wires switched. Renamed easy on the pc as per vbar serial or heli name.



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[bikerlee]

As others have said the BLS251 should do it.
I had exactly the same problem, re-built the tail many times, no real vibes to speak of and finally broke down and got the BLS251. Tail wag was gone instantly and is absolutely rock solid, never had a blowout despite my some hairy bailouts.
Hope the fix is as easy for you to.

[Primus]

Tail unmonted as i post this. No mather how loose or thight the belt is, when rotating the tai pulley by hand, i can barely hear some "click-click" inside de boom and cand feel it also. I think the belt touch something, or some bearing in tail case;

Rebuilding the tail again

[maarset]

Disengage belt and assemble tail. Spin tail. Hear clicking?


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[Primus]

I think I've found it !!!

Unmonted the tail case. On right side "under" the belt pulley on the tail shaft, on the interior of the tail case found some black magic powder .... Déjà vu!

I found one tail case bearing not fully seated on the tail case, rubbing on tail case and touching the pulley also I think.

Cleaned everything, and put some adhesive on the exterior of both bearings. Smooooth!

Rebuilt the tail. no more notchy feel rotating the belt while tensioned and disengaged, and no more clicking

WIll try to do a test in my garage before going to bed

[Primus]

Did a short hover in normal mode at low HS, seems good to me. No wags on take off. Will see on disc loads.

Still some visibles vibes in head/frame, will have a look at those dumpers too.

More to come tomorrow.

[Primus]

Get to the field today. Not solved. Same thing.

With DS620 is doing the same thing. Violent 30-40 deg wag when collective punch or stop from right piroueting; and it's very hard to stop it.

I have no more ideas.




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[galensk]

bonsoir,

sorry to read the wag isn't solved yet...

when can you try the bls-251 ? is there any possibility to show us a short movie of the behaviour ?

kurt

[Primus]

Hi Kurt

Will try to make a movie these days and post it.

Saw that in normal mode, in hover at low speed (TH at about 70-75 ), there are some visibles wobblings in head/frame if that make sense.

The BLS251 will arrive in about 2 weeks.