It's a Goblin Kraken with Spirit Pro. I got confused by high spike in aileron axis. But after some calculations it looks like it is the motor. I run 2050 RPM, with gearing ratio 8,7; this means 2050*8,7 = 17835 motor RPM, /60 = ~297 Hz which is where the spike is. Am I calculating right?

If so what to do - is this some faulty motor, or do I just need more foam below the Spirit? Like two of them?

The motor is Kontronik Pyro 800-48.

Update: forgot to say. The analysis is done on the bench without blades.

Also, what could be the spike with higher freq, which Spirit marks as "Motor"?

What I've done is:
- removed motor belt
- dismounted motor pinion
- made sure the engine mount screws are tight

so now it is only the engine with naked shaft spinning. And just by touching the boom I feel huge vibrations. I can't see anything (like a bent shaft) but touching anything makes it clear. Also, Spirit shows this:



So it is indeed the engine...
I think this is not normal, or is it? Is this a faulty engine?

Do you have the Gov enabled in the Spirit? Make sure you have the correct value for the motor poles and sensing divider (# of poles divided by 2). Also make sure the Gov is not enabled in the esc and the Spirit at the same time.

Hello,

the motor might be simply unbalanced or damaged. It might be undetectable by naked eye. The spike shouldn't be that high for sure.
You might check the bearings carefully. Some bearings can crack if you will insert shaft, gently push radially and rotate.

_________________
Spirit System developer

It's a new Kontronik I just bought for this heli, so I don't want to open it. I've send an email to the supplier and we'll see. Thanks for helping.

I use Kontronik gov, and spirit has it disabled, so should be no problem here. But in any case, I think it could just end up in fluctuating RPM, but here it is very stable, as the spike is always at the same freq.

Hi Thomas

I got the motor back from supplier after repair. I again made vibration analysis. It is done on the bench, and only motor is spinning. It has no pinion mounted. It looks much better now.

At low RPM (I think I have something like 1950 configured) vibrations are not visible on the graph at all. On higher RPMs they do show up. They are much lower then before. Can you please tell me if this level is normal or acceptable?

Hello,

yes, this level is normal.
Some motors are producing lower vibrations but this is already good.

_________________
Spirit System developer

Great, thanks a lot