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 Post subject: Tail tuning video
PostPosted: Sat 28. Oct 2017 17:00:17 
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Joined: Fri 27. Oct 2017 8:46:42
Posts: 20
I have no clue about helicopters, maybe this kind of video can help?! Using the slowmo feature of my phone. The tail holds pretty well but I hear and see small bounces.

The higher the rotorspeed the better the tail holds, at 2200 it's not that good, 2500 acceptable and at 2800 it's quite good appart from the small bounce. Too much gain? I will figure it out my self by time, but I have no clue how close I am. If it's acceptable or not. Totally new to helicopters :oops:






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 Post subject: Re: Tail tuning video
PostPosted: Mon 30. Oct 2017 8:36:04 
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Joined: Mon 29. Apr 2013 16:06:44
Posts: 9070
Hello,

for lower head speed you can increase Gyro Gain. Then it should be better.

Increasing Pirouette Consistency a little bit (maybe 5 points) can help.
You can also tune your governor to help the tail. This has usually very big impact on the tail performance.
In any way I am sure that it is acceptable, but can be always improved :)

Can you upload your settings here (4DS file from Backup tab)?

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 Post subject: Re: Tail tuning video
PostPosted: Mon 30. Oct 2017 11:21:47 
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Joined: Fri 27. Oct 2017 8:46:42
Posts: 20
Hi,

Governor usually holds well I think. Jeti Mezon governor. Maybe the KST servo is not the best either, but again I don't know and will keep tuning before switching hardware.

Thanks for your input.

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 Post subject: Re: Tail tuning video
PostPosted: Fri 03. Nov 2017 16:20:22 
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Joined: Fri 27. Oct 2017 8:46:42
Posts: 20
Got around doing more tuning. The tail assembly did run very smooth, but now after ball link adjustments and 3D printing new push rod support and various fiddeling its ultra smooth. Still no better tail. At high RPM it holds fairly well as in the video but still not 100% lower rpm is shit.

So I bought a new tail servo, MKS HBL880, it's awesome. Simply one insane servo. But the tail still won't hold. I did spin the heli up with no main blades and moving the chopper around Z axis I se the tail work but it wont make force until I move it 100mm at low RPM and like 15mm on high RPM. I tried adjusting all numbers up and down, gain, piro cnsistancy, revomix, delay, dynamic but they don't do much difference.

With the old servo I had 70% gain from the Rx and factor 1.05 or so, with new servo I can do 100% gain from Rx and factor 1.03 or so before it starts to oscilate at higher rpm. 100% Rx and x1.3 factor at low RPM.

*Gyro sits really tight on the 3M tape
*Voltage 8.10volts with alarm at 8.0 which don't go of
*Governor holds well, specially when testing without main blades
*Parameters don't do much difference

I start to believe there are ghosts in the machine haha.....

Probably something simple I miss out on. Will post files later too

lower rpm





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 Post subject: Re: Tail tuning video
PostPosted: Fri 03. Nov 2017 17:12:51 
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Joined: Mon 29. Apr 2013 16:06:44
Posts: 9070
Hello,

thank you for the details.
With current servo it should work perfectly, so you can be sure that this is not weak point anymore.

I can say that each helicopter need a certain minimum RPM to get a proper tail efficiency. With lower RPM, on some models, you can tweak whatever you want, but there is no mechanical room for correct performance.

Governor behavior can make very big difference, especially at low RPMs. If it is doing too big corrections, the tail will never work well.
So governor that is holding headspeed too agressively has same negative impact as when holding poorly.
So there must be good balance.

Next thing is collective pitch range and main blades and also dont forget about belt tension.

Bigger the collective range is, the higher load is at the main rotor, the higher load rudder must compensate.
With lower range you will get always better tail response.

Main blades that are too agressive are putting higher load for tail as well, so adjusting collective range properly is necessary.

Another thing to verify is, how the mechanics is performing in real condition.
Real condition could be very different from what you can check on the ground without rotating blades.
There is simple test:
1. remove all blades
2. unplug push rod from tail servo
3. start the motor to flying RPM
4. move with the push rod (carefully) from end to end.

At this point you will see approximately what force is present.

Another thing to check is rudder neutral position. This is configured mechanically by push rod. If configured improperly, rudder performance will be bad.
With goblin there should be a slight angle so that tail slider is closer to the boom.

From the video I think that the problem is in Governor and its settings. From experience of many pilots we can say that unfortunatelly Jeti Mezon governor is not working ideally and it require tuning or sometimes even using external governor to satisfy needs. Good governor can cause that even with slow servo tail can operate pretty well. It is not that important if head speed is locked, but how it is maintained. Tail is usually the most visible indicator if governor is working well. Unfortunately for unexperienced pilots it is uneasy to distinguish if tail settings or tail mechanics or governor is problem.

Can you please share your settings?

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 Post subject: Re: Tail tuning video
PostPosted: Fri 03. Nov 2017 20:39:58 
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Joined: Fri 27. Oct 2017 8:46:42
Posts: 20
ZeXx86 wrote:
From the video I think that the problem is in Governor and its settings. From experience of many pilots we can say that unfortunatelly Jeti Mezon governor is not working ideally and it require tuning or sometimes even using external governor to satisfy needs. Good governor can cause that even with slow servo tail can operate pretty well. It is not that important if head speed is locked, but how it is maintained. Tail is usually the most visible indicator if governor is working well. Unfortunately for unexperienced pilots it is uneasy to distinguish if tail settings or tail mechanics or governor is problem.

Can you please share your settings?


Reading allot, thinking and finally opening the Jeti mezon manual AGAIN and..... there is gain setting. My ESC speaks Cz, which I don't so I never fount the gain before.

This might be the issue. No more flying today, more testing tomorrow! Thanks so far!

Image


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 Post subject: Re: Tail tuning video
PostPosted: Fri 03. Nov 2017 21:11:15 
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Joined: Mon 29. Apr 2013 16:06:44
Posts: 9070
Great, that is what you can play with.

I can translate any text for you. Zesileni = Gain.

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 Post subject: Re: Tail tuning video
PostPosted: Mon 20. Nov 2017 9:33:24 
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Joined: Fri 27. Oct 2017 8:46:42
Posts: 20
Flying more tuning more, now scanning the logs looking for the best ever governor setting. Started out at 25 and tried a bunch of different levels getting it as good as I can.

I did a 19T tail pulley, DIY from a motor pulley. Works well the higher tail RPM is to my benefit i think.

I also found the goblin tail pitch solution to have quite a bit slop. the pins going in the slider were 1.9mm and the slot 2.15mm. I did new screws for testing that are 2.15mm and its much better. I will do another setup here with tuning parts for sure.

Also tuning the spirit more, with allot of trying and revomixing it's getting close. When I have found my sweet spot on the governor and the new tail pitch assembly with no slop I think I can get it really good.

I will make a sum up after I'm done on how I did it all, maybe it will help someone in the future.

Rewamped 19T motor pulley for tail
Image


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 Post subject: Re: Tail tuning video
PostPosted: Mon 04. Dec 2017 9:04:32 
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Joined: Fri 27. Oct 2017 8:46:42
Posts: 20
I have made progress and still have wonderings or what to call it. haha...

I have changed stuff I did not like about the Goblin. I bought the MKS X8 servo, pushes almost 12kg but makes no sense when the stock pushrod flexes at 3kg!

Image

So I upgraded to a wowen 6mm pushrod that can do more then my thumb was capable of.... 16.5kg was my hands limit. Removal of the support in the mid of the boom too. NO friction!

Image

Image

I also eliminated slop by getting the helioption tail slider. The stock solution is really not good and the lynx upgrade is not much better in my mind.

Image

this made it much better over all getting the tail to work with a combo of parameters, governor(which did not seem to be the key) and revo mixing.

I now made a stretch kit for it and fitted larger blades, VTX 557. Now turning at even lower RPM I did stall the tail at 2100rpm. I could clearly hear the tail stall and see the heli twist. that is fine as I know the cause of the twist. At 2350rpm the tail worked better, so I geared the tail even more with 17T pinion. Now it eorks "good" at 2100rpm too. I just switched to NHP 95mm tail blades which were cut to 80mm. These provide more surface and a much thicker profile. I will not have to re do much of my tail tuning.

I find the solution to be one part mechanical slop, one part the tail might not be strong enough at lower RPM on the goblin 500 and one part the spirit reacts too little to motion.

The spirit could be faster to punch when the heli starts to spin, no matter which parameter I tune I can not find this snappiness I search. like in PID regulator I don't find a true P, a true I or a true D.

Spirit seems harder to tune the tail then other gyros I have tried before. It holds super but the ass-wiggle at pitch pump is really a pain to get around.

Image

Image


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 Post subject: Re: Tail tuning video
PostPosted: Mon 04. Dec 2017 9:21:42 
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Joined: Mon 29. Apr 2013 16:06:44
Posts: 9070
Thank you for your updates!

You have did big piece of work. From our experience it is not needed to buy any super strong servos. Actually it is better to have just as fast as possible. If the mechanics is working really smoothly, it can work well even with slower servo.
But it all depends on your requirements. If you want to make it work with too low RPM it is hard always.
Normally it is working usually in the first flight already quite good for the most pilots. So they are actually telling us that it is easier than with any other gyro, hehe :)

I have found that as soon as pilot have to use revomix, something is wrong. Unfortunately in some models it is uneasy to make the mechanics working well.
Some models have tight ball linkages but less experienced pilot will think it is just good since it is new - it must be good :) But it is usually the main reason why tail can't work well.
Even after hundred of flights they will work still tightly. Next thing is how the mechanics is behaving during spinning - this can make extremely big difference too.

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