I'm cross posting from helifreak, but because it's always down lately I'm moving to here.

I'm consistently getting an error in my spirit log that says "Main Loop Hang Occurred." I'm also the individual that is having issues with the spirit on a Mostro and can't get rid of a bad bounce on hard stops (and have now twice lost complete control while the unit does several flips before I regain control). The cyclic ring value was asked on helifreak. My value is 215.

I can't pinpoint the exact point the error occurs to when I get the dangerous bounce, but it looks like when the bounce gets to borderline losing control, I may be getting the main loop hang error. It also seems to be random. Sometimes it will fly with little bounce, other times it will get really bad. This is on the same day, so weather doesn't play a part.

I've tried lowering gain to 40 and ele filter to 3 and I see no improvement. No tuning seems to help.

My setup:
Avant mostro
Kosmik 160HV Cool
KDE 700xf
BK BLS8001HV / Torq 9188 running at 6.6v
Spek AR9020 / TM1000

What angle on the blades do you achieve with full elevator/aileron stick deflection when collective is midstick?

I recommend to decrease Cyclic Ring - Aileron / Elevator Value to for example 10°.
Altough I do not recommend to fly when we don't know yet, what is the cause for such strange behavior.

It shouldn't happen in any case. Can you please send me your settings?

If you said that it started from the crash (and also it does happen with both units you have), then I would search for all things that changed from this time.

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Spirit System developer

I know it is well over 10 degrees deflection. I followed directions and kept going until binding and backed off. I can back it off to 10-11. I usually run 11.

The heli flies perfect. I've tried a buddies brand new head assembly and same issue. The only other parts would be swash and main gear. Swash looks and feels fine.

But would cyclic ring cause the main loop hang error? What exactly does that mean? And do you think that error could induce the issue I'm having?

I'll have to send settings later.

One odd thing noticed yesterday in 80 F temps is the servos became hot. Not too hot to touch, but servos don't tend to get that hot. The motor was very hot (as KDE tends to) and the whole mono-block was hot from the motor. But that would seem like a lot of heat transfer if it went to the servos.

My settings as last saved before trying a new wizard install. Nothing has changed much, and I had the issue with those settings and with my current.

Thank you very much for the settings.

First from all I recommend to set servo frequency to 200Hz. There are lot of servos that are rated for 333Hz, but they are getting hot.
There are just few FBL systems that are capable of 333Hz on cyclic. VBar, BD is putting only approx 170Hz to cyclic servos.

If Cyclic Ring limit is way too high, it may cause some issues.
Also I recommend to redownload version 1.1.0 and flash it there, just to be sure everything is OK.

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Spirit System developer

Also I recommend to increase Elevator Filter to at least 2 or 3 for this helicopter size. It may reduce issues with hard stops.

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Spirit System developer

thanks.

I've tried ele filter up to 4 with no help. I originally flew with 1.

I can try lowering freq and cyclic ring.

I'll try flashing again, though this issue has been happening since two firmware old (started beginning of Jan). I've been trying to resolve this issue since then (ugh).

I'll try these last two things. Then I'm going to try a beastx I have just to rule the frame out.

The one last thing that is different from original setup (besides cyclic ring. I had that lower originally and since increased it) is my linkage geometry. Originally I was using 13mm on servo horn for 90 degree linkage at 0 pitch. But I had since learned that Mostro recommends angled linkage at 90 degree using 17mm horn. The FBL wouldn't care about this would it? I re-ran setup when changing (cyclic ring, pitch, 6 degree setting, subtrim).

Another odd point. I was running Revoultion 710 blades. Switched to a buddies RJX 690 blades and the bad bounce was gone, I just couldn't completely tune it out. Thought I was on to something, but then flew yesterday and had the 2nd uncontrolled flips with the RJX.

It gets worse the higher RPM I go.

Hmm, mentioned distance is very important factor that can change behavior a lot.
It is important because geometry head and servo travel is changing.
It is very same as for the rudder, so the distance can make big difference.

Each FBL unit is "prefering" different distance to get best experience, because there are different servo travel compensations.
So I highly recommend to try to put linkages back to 13mm if possible.

Can you desribe these flips little bit more?
I am nearly certain, that there is something very wrong (maybe caused by higher temperatures) but if helicopter is doing flips on its own, then it can't be changed with any settings. It is also very dangerous.

As I said earlier, exactly same behavior was caused by faulty RJX servos in the helicopter of friend, thay are nearly identical with BK.
It was hard to determine which one was faulty initially, but problem was worsening. Elevator servo was first that failed to maintain its position in some cases.
You can try different FBL unit to make sure problem is there, but it is very dangerous.

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Spirit System developer

I don't think it is heat issue. This happens in cold weather as well. THe spirit never gets hot. And all servos were about the same heat. If one was an issue you'd think that one would at least be noticeably hotter. I will try lower freq to see if that helps.

I am changing back to 90 at 0 right now to see if it helps.

have the shorter arms on now. My cyclic ring is 225 and my pitch is 240. This is to get 11 degrees deflection and 13 pitch. About to go test fly.