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Toilet bowl effect in Lynxed 180cfx
https://www.spirit-system.com/phpBB3/viewtopic.php?f=20&t=2544		 Page 1 of 3
Author:  Tech 4 9 [ Mon 30. Apr 2018 19:12:39 ]
Post subject:  Toilet bowl effect in Lynxed 180cfx
Hello all,

98% Lynxed trio 180 cfx.

Spirit fbl

Only thing not Lynx is main gear and tail blade grips

Stock cc talon 15 esc

Lynx belted tail conversion

Blue arrow servos

Brand new main shaft and main bearings

I bought this thing second hand two weeks ago and so far all it wants to do it tip over and tear itself apart on spool up. If I hold onto it I can feel it wanting to toilet bowl.

Same result with either the stock bullet blades or lynx blades

This is first 180 I've ever owned so I don't know if it's just simply to heavy from lynx stuff or if head is outta wack or if it's a fbl issue. I'm currently trying to make sure blades are tracked but that's challenging with three black blades. Paint pens I guess?

Tracking either wasn't that bad or doesn't seem to help as much as I'd hoped although I'm not done done yet. Tough to see. I'm sure it's a ambiguous vibration issue (kill me now). Or it's just too heavy. I've looked at the the vibration analysis in spirit software..but then wonder why..as I don't know what to do with that ambiguous info..which didn't seem to change after main shaft/bearing replacement even though the program seemed to suggest this replacement. (shrug)

Don't know if blades are balanced as I've yet to find a balancer for those small of blades. They weigh about the same fwiw.

My only next step is to slowly start taking it back to stock to reverse diagnose issue starting with replacing whole lynx tri head with either the lynx two-blade or stock two-blade.

Thanks for any input.
Author:  ZeXx86 [ Mon 30. Apr 2018 19:23:25 ]
Post subject:  Re: Toilet bowl effect in Lynxed 180cfx
Hello,

maybe you can check if unit is compensating correctly.
If swashplate and tail is moving in the wrong way, then it will be impossible to lift off.
On the other hand with correct compensation it must be able to fly.
Author:  Tech 4 9 [ Mon 30. Apr 2018 20:11:24 ]
Post subject:  Re: Toilet bowl effect in Lynxed 180cfx
Thank you for the quick response!

I have a battery charging now to continue diagnosing.
While I'm waiting I will say that the spirit vibe analysis shows a literal off the scale spike that's labeled either 'main motor' or 'main rotor'..this varies I think..either way it's off the scale by at least mid throttle perhaps even by 1/4. Spike is of scale throughout the rest of throttle travel..only change is that at approximately 3/4 throttle the label over the same spike saying 'main rotor/motor' changes to 'tail rotor'. Frequency related I gather. The huge 'main rotor/motor spike led me to change main shaft and main bearings, at least one of which was wicked rough so I thought I had it, but huge spike remains after the change.

I'm thinking this is going to be head related which is hard to believe since lynx tri head is quite beefy but I don't know what the models been through before I received it. It may have never flown for all I know. Guess it could be a bent/stretched feathering shaft or blade grip. Also still need to make sure blade tracking is close.

The tape holding spirit to airframe is almost solid. No give at all it seems. Is this desirable?...or should it be a little more 'spongy' to help isolate?

Batt should be ready soon.
Author:  Tech 4 9 [ Mon 30. Apr 2018 22:17:55 ]
Post subject:  Re: Toilet bowl effect in Lynxed 180cfx
I messed with it some more.

I don't know. I think this thing is just all kinds-a wrong.
Should I be pushing 5500 to 6000 rpm headspeed? (stock 3s setup)
This time, at 3/4 throttle with all blades on, the model emitted some crazy noise I've never heard. Like bearings are getting spun to fast or gears are stripping but I can't tell if it's coming from head or tail. Tail would be my guess as it tends to go nuts with wag with gyro set to 40%.

At one point I ran spirit vibe analysis with head completely off. Just swash. The crazy off the scale 'main motor' spike on aileron was still there. Looked the same as with head on. (shrug)

I guess I can replace the bearings in tail assembly just to blindly see if it helps...assuming I can even find them.
Author:  Tech 4 9 [ Tue 01. May 2018 23:53:31 ]
Post subject:  Re: Toilet bowl effect in Lynxed 180cfx
Can the compensation be reversed? If so is than in spirit pc program or in TX? (invert the gear channel?)
ZeXx86 wrote:
Hello,

maybe you can check if unit is compensating correctly.
If swashplate and tail is moving in the wrong way, then it will be impossible to lift off.
On the other hand with correct compensation it must be able to fly.
Author:  ZeXx86 [ Wed 02. May 2018 7:35:25 ]
Post subject:  Re: Toilet bowl effect in Lynxed 180cfx
Hello,

if you are unsure, you can save the plots. I can tell you what is likely source of the vibrations and what could be wrong.

It is better when unit is holding hard without any movement.

Compensation directions are all programmed in the unit.

If your model was bought from some person (including unit) I guess that it was never really flying. So re-doing complete setup from scratch could be better.
The swashplate should tilt when you tilt the model so that it is trying to keep level with a horizon.
Author:  Tech 4 9 [ Wed 02. May 2018 13:43:07 ]
Post subject:  Re: Toilet bowl effect in Lynxed 180cfx
Ok thank you.
I think something is out of balance in the head. New head parts in this weekend then I'll go back through all the set up.
When running vibe analysis I can save images but when go to folder they're stored in my pc doesn't recognize stored image so I can't see it but I'll try to take some phone pics of screens to post here.
Hopefully new head cures all.
Author:  Tech 4 9 [ Sun 06. May 2018 22:12:05 ]
Post subject:  Re: Toilet bowl effect in Lynxed 180cfx
I GOT IT!! IT FRIGGIN HOVERED FOR THE FIRST TIME SINCE I'VE HAD IT. WOO!!

You were right..the compensation was backwards. I had to reverse swash in spirit and reverse all three cyclic servos in TX.

IT FRIGGIN FLIES!!

Now....why do I have to have gyro set to 30% to get rid of tail twitch that developes into wag that developes into CRAZY wag as throttle/pitch increase? Rudder gain in spirit set to the 1.00x multiplier as suggested. No tail settings in TX. Is it revo? Stabilization set to stabil acro.

Thanks.
Author:  Tech 4 9 [ Mon 07. May 2018 0:35:52 ]
Post subject:  Re: Toilet bowl effect in Lynxed 180cfx
Wicked bad, fast tail wag.

I can just get it off the ground with it twitching but within seconds its wagging out of control.
Author:  wheelstoo [ Mon 07. May 2018 0:45:24 ]
Post subject:  Re: Toilet bowl effect in Lynxed 180cfx
what head speeds are you running.
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