Vibration analysis.

Hi

I am just trying to find a vibration on a model and run the analyser blades off.
Never used it before so not sure what to expect, but I noticed that the head and tail reading are clear to read but the motor has the second text overlayed over it as shown that only separates briefly when you change speed.
Does this imply a motor issue?

Thanks

I have a heavy low frequency vibe in hover whole Heli shaking tracking ok blades are ruled out as cause.
New build Heli OMP M7 ( where is that Logo 700 ) I suspect there is an issue with the thrusts in the head, I have run blade less up on bench re pics above and head area vibe is low so next step is to hover again and re check vibes on that frequency.

Is it possible head could be dynamically balanced OK but when it is loaded up with flying loads from the blades and error in there could induce a heavy vibe?

Thanks for any input in advance.

Many thanks



Edited 3 time(s). Last edit at 07/04/2026 04:30PM by ChrisB.

So you have already tried another set of blades?

If so - i would check the main head assembly.
As said the thrust bearings could be defective or mounted in wrong orientation and - probably the dampeners are different.
A last thing might be the blade shaft to be checked wich is a easy task, remove one blade and rotate the shaft with a hex driver so you have the remaining blade as a XXL pointer ;-)

regards (EN) / Gruss (DE)

Rainer Vetter

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Thanks Rainer will check these things.

Hi Chris,

at which rpm? Does it change amplitude or frequency, when you change rpm?
Can you elaborate on what you see, or share a short video (upload somewhere where videos belong, post a link, because of the file size)?

Some more thoughts:

What I found sometimes, even with today's blades which are pretty much well matched if not exactly balanced (any more ...), the good old 'Schlüter Magic Tape' can help: add a strip of electrical tape to approx. the cog of one blade, try again. If it gets worse, try the other blade.
Or—if available—use a rotor blade balancer.

With thrust bearings, please mind that not only the order in which the rings are mounted counts (feathering shaft<-large inner diameter<-ball cage<-narrow inner diameter<-thrust washer<-bolt<-blade holder w/ blade), but also the way the ball cage is mounted: with large thrust bearings, and if the cage is mounted pointing to the outside (myth: to keep the grease in place), the balls can beach on the cage eventually, and block the bearing or even destroy it. Mount it with the bearing balls pointing outward to avoid that, the cage is only meant to guide the bearing balls, not to act as a grease sump).

—Eddi

Born to fly ...
forced to work.

Thanks Eddi, will gather more info and report back if needed.

Tracking adjustments seem to have cured it.

good! That's a thing I (so rarely I didn't think of it before) also found: where you should think that links of equal length equal perfect blade tracking, in real life it may be necessary to adjust, and sometimes even only a half turn. Tracking (before) may even look razor-sharp in a hover, but it's still somehow/somewhat off.

—Eddi

Born to fly ...
forced to work.

Thanks, tracking was not too bad but it seemed to produce a load of vibration to what I have seen before, seems fine now.