Logo 400 Vibrations - Help!

I getting very frustrated at the moment trying to get my Logo 400 back to flying as it was before I had a tail servo failure resulting in a hard auto landing.

I have re-built the main rotor, shaft, tail, bearing etc, and I thought I had it nailed when I was able to get the spectrum in the pciture "ZealStockBlades". This is running full RPM on the bench. Original black mini v-bar.

So I put on a set of balanced blades, and the swash plate is twitching like mad, making the flight very unstable.
Tried a different set of blades, same result. My tracking looked OK.

I then looked up my laptop with a long thin USB cable and took the spectrum "withbaldes" on the ground.
I would have expected some vibrations from the main rotor (2100 RPM so ~35hz) and it's only just about the yellow line, but what are the other peaks equally spaced around?? I have put new main bearings in when I changed the shaft.

Any help would be great to get my Logo back to being rock solid

Using a black device on the 400 - we always recommend the big one with the external sensor.

Unfortunately is the sensor placement over the tail boom not the best. A Blueline mini will be able to ignore these vibs partially, a black mini is on the edge there. Maybe we get this sorted out, maybe we have to move the unit to the bottom, use a black fullsize (sensor on bottom) or blueline.

The Spectrum "withblades" looks like a gear mesh or motor problem. Can you try with tail blades only once again? If it is still there, it can be the gear mesh from main gear to the tail drive.

regards (EN) / Gruss (DE)

Rainer Vetter

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Thanks. I tried mounting the mini vbar on the bottom of the frames, and did this no seem to make any difference.

It used to fly OK, so should I send my mini vbar back to Mikado for it to be checked?

What sort of "motor problem" can it be? Maybe I will convert to Mod 0.7 gears. Will that help?



Edited 1 time(s). Last edit at 10/06/2010 01:33PM by pgleesonuk.

It looks like vibrations from the motor under load at the first view.

Maybe the motor or its shaft is a bit out of balance.
That can also be a gear mesh problem, maybe a bit too less gear mesh. Or a pinion problem.

Try a bit more gear mesh on both (motor and tail drive) first. The mod .07 gear won't help.

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.

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Still trying to get it to be smooth.

Can anyone post a "good" spectrum for a Logo 400?

I was able to significantly reduce my vibrations to around 200 without main blades. :-)

What did the trick was the alignment of the tail gear to the main gear.
I'd really tried hard to assemble this as carefully as I could.

I discovered this by setting the heli level, and checking the main gear was spot on level with a spirit level.
Then I check the boom. It was slight too low.

This would also affect the center of gravity, as I "assumed" the boom is 90 deg to the main shaft.

No chance of seeing this by eye. It was only the combination of leveling the main gear AND the tail boom.

Just thought I'd share this tip.

WOW - Great news. Thanks for sharing!

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.
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Hi just converted my Logo 400 to a logo 400SE spinning 470mm blades.

After a really careful rebuild and checking all my angles with a digital gauge (Particularly the boom to main shaft angle) here is the result with edge tail blades fitted.

To say I am pleased is an understatement.

I also checked all the angles for the vbar mounting. All within 0.2 degrees. It flies like a dream now.

:-)

Paul

Just for fun I tried this to visualise any vibrations

http://www.youtube.com/watch?v=s3iHHq3bRtI

Kind of a competition between a friend of mine to see how vib free we can make our machines.

Paul

WOW! I'm very impressed ;-)

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.
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Nice!!