SOLVED Spirit RS and Geolink - stabi / rescue / RTH issue

[Fortune7]

I investigated the high tail vibrations and found the torque drive tube was bent (!). This is embarrassing, as it's the only heli I bought used and I thought I'd checked it over thoroughly....... It looked like the tube had been 'straightened', maybe more than once, as it had a couple of bends. Now I've replaced it with new + bearing and the vibration plot looks much better - see here: (Y axis).

I hope this fixes the problem but it will be a few days before I can test fly.

Looking at the vibration plot for the other axes it looks like I have a problem for the X axis as it's reporting 100% vibrations, see here:

This vibration seems to cover a wide range of frequencies, unlike the other axes where 'peaks' show clearly where (e.g.) main rotor or tail rotor issues are. Of course I can systematically remove parts of the head / swashplate, etc. and re-test, but I've already made sure the main shaft is straight (in the lathe with a dial test indicator).

Can anyone who's familiar with these vibration plots provide any guidance, please? With the tail (Y axis), it was an obvious 'fix' but with this X axis plot, I don't know where to start!

Thanks to those who pointed me in the direction of 'vibration' - we live and learn but it takes me a bit longer to do the learning part!

Cheers, Andy

[ZeXx86]

Hi,

thank you very much for the plots.
It looks much better now.

Regarding X axis it is not looking normally. From the plot it look like the unit itself is not holding firmly.
Could you please verify that the electronics in the aluminium enclosure is holding well?

It should be enough to hold (connected) servo connectors and try to move with them to a side (wiggle). There must be zero play.

Or is there something that is bouncing to the unit?

This could develop such strange vibrations.

[Fortune7]

Hi,

thank you very much for the plots.
It looks much better now.

Regarding X axis it is not looking normally. From the plot it look like the unit itself is not holding firmly.
Could you please verify that the electronics in the aluminium enclosure is holding well?

It should be enough to hold (connected) servo connectors and try to move with them to a side (wiggle). There must be zero play.

Or is there something that is bouncing to the unit?

This could develop such strange vibrations.

Thanks, Tomas for your quick and helpful reply. When I checked the unit as you suggested I noticed that the Y connector I fitted to the SYS port (to make it easier to connect the USB cable) may have been vibrating against the case - see pictures.

I wouldn't have thought this could be an issue but after your guidance can now see why it might! I moved the connector and yes, the X axis vibration plot is much lower - around 40 maximum. I had flown with this connector in-place, loose next to the unit. In future I will remove the connector and hopefully the problem is solved. I will report back when I have test-flown. Again, many thanks for your help on this.

Andy

[Fortune7]

Well, after a week of delay I test - flew the heli today and the problem is not solved, unfortunately. I really thought that the new tail parts and removing the 'loose' connector next to the spirit unit would solve it! The vibration plot in each axis, particularly Y (Ail) is much better (though it still is around 58) but clearly this was not the cause.

I'm losing faith a bit in this heli - it's the only one I didn't build myself (bought used and updated some 'obvious' worn parts), and having fitted the Spirit RS and Geolink recently I can't point to a working setup before. It did work well with the BeastX but I wanted the Spirit/Geolink combo. I believe I can eliminate the transmitter or Tx programming as the swashplate responds correctly to rescue before flight, but in-flight either rescue, stabilisation (normal) or RTH causes the swashplate tilt. I've made sure the unit is calibrated level (see my figures in previous posts), taken Tomas' advice re: expert settings and minimised the vibration. I have other helis to fly so I may give up with it and put the SpiritRS and Geolink in my next (new!) heli......

I'm happy to try any suggestions; if the Y vibration is still considered too high at 58 I'm really not sure what else to replace to reduce it.

Cheers, Andy

[ZeXx86]

Thank you for the message!
I guess the BeastX unit had no stabilisation/rescue enabled or yes?

I want to ask if you have tested also settings with Stabi Correction OFF and Extended Signal Processing OFF?

We can send you new unit for comparison.

[Fortune7]

Thank you for the message!
I guess the BeastX unit had no stabilisation/rescue enabled or yes?

I want to ask if you have tested also settings with Stabi Correction OFF and Extended Signal Processing OFF?

We can send you new unit for comparison.

Many thanks, Tomas - helpful as always!

Now, on a different day, perhaps I should not give up so easily . I want to eliminate the possibility of vibration, so first I will try your suggestion to try with Stabi Correction and ESP OFF. If no improvement, I will remove and re-mount the unit and see if (perhaps) there is some kind of vibration caused as a result of the original mounting, which is on the proper supplied tape. I will also remove again the mainshaft and head, re-check for straightness and static balance with blades on. After that, if the problem persists, we'll try another unit!

I didn't fly much with the BeastX, but it seemed fine and the Rescue/Stabilisation performed OK.

Thanks again, Andy

[ZeXx86]

You are welcome.

If it worked properly with BeastX then it should with Spirit too. Actually RS unit has better sensor.
If you will redo mounting I highly recommend to not bend antennas too much.
From provided photo it looks like it is not ideal. Antenna lifetime and performance might be improved if bending radius will be over 3cm.

It should be visible from vibration plot. If you can share it I can let you know if it is good or no.

[Fortune7]

You are welcome.

If it worked properly with BeastX then it should with Spirit too. Actually RS unit has better sensor.
If you will redo mounting I highly recommend to not bend antennas too much.
From provided photo it looks like it is not ideal. Antenna lifetime and performance might be improved if bending radius will be over 3cm.

It should be visible from vibration plot. If you can share it I can let you know if it is good or no.

Thanks, Tomas!

I'm trying not to make a comparison with the BeastX; I really didn't fly it much then and had already decided to move to the Spirit, for all its advantages. I firmly believe the problem lies with the heli mechanical setup and/or the unit mounting (if indeed vibration is the root-cause). Once we eliminate this, we can move on. I will also find a better way to route the antennae - thanks. I really appreciate the close-support from you here and for me, the main reason the Spirit is such a successful product. I'll be back with an update soon.

Cheers, Andy

[Fortune7]

Flew again today and the problem is solved - everything behaves as normal. Everything pointed to 'vibration' being the source of the problem, from Tomas' advice and also looking through similar posts regarding stabi/geolink/rescue issues. Since the last post I did the following:

1. Removed the SpiritRS unit from its mounting and (because I'd already re-calibrated the level before), put the unit directly on a known level surface. I have a granite surface plate in my workshop, set with a machinist level which is accurate to 0.0005" in 12". This was to make sure the calibration was (hopefully) as good as factory-original.
2. Replaced the SpiritRS on the heli with supplied tape, but positioned back a little to improve the antennae routing for larger bending radius.
3. Re-checked the head/mainshaft/blades static balance by securing the heli on its side ,mainshaft horizontal, drive gear removed. Good bearings and VERY slight correction needed by swapping blades to opposite holders which balanced well.
4. Reassembled and set the SpiritRS to factory settings, then went through entire setup again. In Expert settings: Stabi Correction enabled, Extended Signal Processing Disabled.

I wish I could be definite about what the actual cause was (!) as doing all the above effected the solution. In my previous posts I did improve tail vibration to 'acceptable' values, so I can only assume the unit needed the factory reset, as I'd previously corrupted it somehow.

To conclude, and in future I will first look at vibration for similar issues, then if all else fails do a reset and start again fresh.

Thanks to all who responded and to Tomas who took the time and patience to provide support, even offering to send me a replacement. I'm really pleased to have avoided that embarrassment!

Cheers, Andy

Cheers, Andy