Logo 800 slow/irregular tail wag

Hello,

Struggling with a slow, irregular tail wag on all RPM’s (1400/1600/1700 RPM) on my 800.
What is really strange is, is that it occurs irregularly. For example in a hoover the tail holds 1 or 2 seconds and starts to slowly wag back and forth than it stops and starts again. Stick input does not affect this. Same problem on all banks.
Increasing Tail gain did not help, decreasing neither. Also Changing gov gain didn’t change anything.
Same problem in Vbar gov and scorpion gov.

My setup:
Logo 800 with scorpion 4535-380kv motor
Neo vlink (with VBCT)
KST DS725mg cyclic servo’s
KST DS525mg tail servo
Tribunus 12s 130a ESC
Blades are stock and brand new. Heli was never in a crash and had 10-15 calm flights So far.

No hard 3D only hoovering and flying circuits/stall turns..

As usual I checked the tail thoroughly:
Pitch slider is smooth, blade holders are smooth, thrust bearings as per manual, tail push rod is smooth.

I tried to solve it with the new wag suppression in VBar but with a value at 70-80 it seems the Distance the tail Wags back and forth is less but still there,in a more condensed way let’s say. I guess it’s not normal I have to crank up that value so high..

I’m suspicious on the tail servo. Maybe difficult to advise me on this, but could the tail servo be the problem? I’m thinking of buying a BLS276sv futaba servo but off course I don’t want to spend the Many and still having the issue..

Any ideas what I could do?
Many thanks

Bart



Edited 10 time(s). Last edit at 08/16/2020 05:09PM by ROMULUS.

I have the 800 running 1340 1/min and all stock main/tail blades w/o tail wag suppression dialed in , running Main Sevros: KST X20-2208 V2 and Tail: KST X20-1035-V2. All ok here.

So - might be the servo (poti issue at one defined position) - or - please check the rod (glue connections) first, could be probably be loose a bit.

regards (EN) / Gruss (DE)

Rainer Vetter

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Posting and answering - please use a PC and a standard keyboard. Answer all questions fully, take the needed time, don't forget probably requested attachments.

Für Posts und Antworten bitte einen PC und eine richtige Taststaur benutzen sowie alle Fragen vollständig abarbeiten. Nehmt Euch Zeit, beantwortet Rückfragen in Ruhe und vollständig.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Für Einzelkommunikation bitte ausschließlich Email verwenden! - PN, Messenger, Chat usw. werden nicht bearbeitet.
For single user communication please send a email only! PM, Messenger, Chat etc. won't be read.

Hello Rainer,

Today I checked the rod and no play on the rod. The glue connections are solid and no play. I changed the KTS servo for a new futaba BLS276sv,
Unfortunately the wag is still there.

I grounded also the tail with the anti static wire. Installation done as per manual.
As the wag occurs from time to time (not constant) Could it be a charge/discharge process? As I don’t have a ferrite ring on my ESC wire could that be the issue?

Thank you for your help

Bart



Edited 1 time(s). Last edit at 08/17/2020 04:36PM by ROMULUS.

Could you please chaek thrust beraings again, especially the shims where the balls will move. Also check for different inenr diamters (wiggle teh sims on the shaft).

regards (EN) / Gruss (DE)

Rainer Vetter

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Posting and answering - please use a PC and a standard keyboard. Answer all questions fully, take the needed time, don't forget probably requested attachments.

Für Posts und Antworten bitte einen PC und eine richtige Taststaur benutzen sowie alle Fragen vollständig abarbeiten. Nehmt Euch Zeit, beantwortet Rückfragen in Ruhe und vollständig.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Für Einzelkommunikation bitte ausschließlich Email verwenden! - PN, Messenger, Chat usw. werden nicht bearbeitet.
For single user communication please send a email only! PM, Messenger, Chat etc. won't be read.

Hello Rainer,
Checked the thrust bearings and all good. I even bought a complete new set but no change.
I changed also the tribunus ESC with Kontronik jive To test but issue still there.
I made a video in flight:

https://youtu.be/fZR5NP4L7uo

In the video you can see the tail has a slight lateral move, here in hoover (+/-1500RPM) but also in Idleup (+/-1700RPM). Changing tail gain does not affect the frequency.

We discovered also that the tail has the lateral move while tail servo is disconnected from tail (Bench spoolup with tail blades installed).

Any ideas what could be wrong. The machine is flyable but it drives me crazy while in hoover.

Thank you



Edited 1 time(s). Last edit at 09/13/2020 06:11PM by ROMULUS.

Could you upload to youtube or a filesharing service?

regards (EN) / Gruss (DE)

Rainer Vetter

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Posting and answering - please use a PC and a standard keyboard. Answer all questions fully, take the needed time, don't forget probably requested attachments.

Für Posts und Antworten bitte einen PC und eine richtige Taststaur benutzen sowie alle Fragen vollständig abarbeiten. Nehmt Euch Zeit, beantwortet Rückfragen in Ruhe und vollständig.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Für Einzelkommunikation bitte ausschließlich Email verwenden! - PN, Messenger, Chat usw. werden nicht bearbeitet.
For single user communication please send a email only! PM, Messenger, Chat etc. won't be read.

Hello Rainer,
I’ve updated my previous post with YouTube link as well.

Thank you

Hmmm ... i can't see any noticeable tail wag which should/could be fixed. This is quiet normal from my opinion.

But - if you think it has something to do with a flexibility in the tail boom or its support- check the 2 carbon tubes and their ball links / glue.

regards (EN) / Gruss (DE)

Rainer Vetter

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Posting and answering - please use a PC and a standard keyboard. Answer all questions fully, take the needed time, don't forget probably requested attachments.

Für Posts und Antworten bitte einen PC und eine richtige Taststaur benutzen sowie alle Fragen vollständig abarbeiten. Nehmt Euch Zeit, beantwortet Rückfragen in Ruhe und vollständig.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Für Einzelkommunikation bitte ausschließlich Email verwenden! - PN, Messenger, Chat usw. werden nicht bearbeitet.
For single user communication please send a email only! PM, Messenger, Chat etc. won't be read.

I see the tail wag. I would change the shim in the tail between the radial and thrust bearings to a bigger size. It can be an issue resulting in a wag if not centered properly. You can replace the shim with a 8x12x.5.

I did this on my Logo 700 and there is zero wag. I will do this on my L800 when I start the build.

Hope it helps.



Edited 1 time(s). Last edit at 09/16/2020 01:54AM by spencerkey.

Hello Spencerkey,

Hmmm, interesting point you raise there. Never thought of changing/checking this part.

Could you provide a link of the shims you are referring to/used for your L700?
You do well mean the shim between the yoke and the thrust bearings in tail section, right?

Thanks!!



Edited 2 time(s). Last edit at 09/23/2020 10:31AM by ROMULUS.

I just built a Logo 700 and Logo 800 and replaced the tail shims. Zero wag. Here are the shims you will need. You will need to buy two since the correct sized shim (8x12x.5) has one per bag.

https://www.amainhobbies.com/align-500pro-main-shaft-spacer-agnh50157/p215265

Per the manual, replace the 7x10x.5 shim which is in the tail grip. It’s in between the bearing and the large inner diameter disk with the new 8x12x.5 shim.

If you go on Helifreak you will see this was an issue when the Logo 700 was released. The problem was the original shim was not seating correctly and would cause a slight wag in the tail.



Edited 4 time(s). Last edit at 09/25/2020 05:47PM by spencerkey.

Thanks Spencerkey, for the very clear description.

If this is/was a known problem, it’s very surprising Mikado doesn’t change the shims in the kit. I simply just don’t understand for such a strong brand with overall a fantastic customer service. i bought this kit in March of this year!

After spending that amount of money on a heli, a customer shouldn’t have to worry about this kind of issues and buying other shims to get a solid tail.

I’m chasing this problem for months now, tried everything and changed almost every part in the tail.
Very frustrating experience. Planned to build a L700 but lost confidence.

Thanks again



Edited 2 time(s). Last edit at 09/25/2020 10:03PM by ROMULUS.

I agree. Mikado should have addressed this issue by swapping out a 1 cent shim to avoid potential tail wag issues. Or at least let it be known. I’m sure their defense is this is an isolated issue and not a mass problem. I know some guys who super glued the Mikado shim to the bearing so it seats correctly.

I found this on Helifreak where guys were having the same issue and someone posted this link. https://www.vstabi.info/forum/read.php?56,157308

I will say the new Logo 800 is a fantastic helicopter. Perfect for big air/sport flying. On 12s at 1525 rpm it is perfect for my style of flying.

Keep us posted if this solves your issue.



Edited 1 time(s). Last edit at 09/25/2020 10:49PM by spencerkey.