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HomeRC & Power✈️Aircraft🚁HelicopterFlybarless Rotor Head SystemsV-Bar › V-bar 5.1 tail kick on a Synergy E9
05-02-2011 12:41 AM  10 years ago
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bmw576

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Traverse city MI USA

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V-bar 5.1 tail kick on a Synergy E9
I am pulling my hair out over this one. When I do a collective punch on my E9 my tail will kick over a foot to the right after a moment the tail will fix its shelf. At first I thought it was the servo not having the balls to keep up with the power of the heli so it was replaced. I can do a tail slide and the tail will hold true all the way down the same is true with tail first flight. I have messed with the gain I brought it all the way up to 120 with no change.
Later tonight I will run the vibration test with no main blades

Synergy E9
JR 8717
Futaba 251 on the tail
V-bar Edge 5.1
693 main
105 tail
Jive 120HV
4035-530 12S
Thanks for your help guys
Branden
Team Synergy, Synergy E5, E7, E9, N5c and N7
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05-02-2011 01:40 AM  10 years ago
TattooArtist

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Chestnut Ridge NY

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vbar
i just got into vbar.myself
but i believe it has to do with your pre comp
for the tail..it ads tail pitch as u give collective..
to comp for torque.
hope this helps
Alex
Team Synergy ,RcRcc,
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05-02-2011 05:07 PM  10 years ago
TT2

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Nakhonsawan Thailand

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Try bigger tail blades? 115mm or 120.
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05-03-2011 05:25 AM  10 years ago
Sam2b

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Tacoma, WA

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I have a few different things to ask and point out in order of importance:

When you say it kicks the tail over one foot, do you mean counter-clockwise?

How much right thrust do you have mechanically while the tail servo is at center? It helps to have approximately 1~3 degrees of right thrust in my experience with the Vbar (v4.0, 5.0, 5.1). Right thrust is simply adjusted by shortening the tail control rod connecting to the tail pitch slider. Ultimately right thrust is when the tail blades bite air in the clockwise direction, or nose right. Almost nothing will compensate for a correct mechanical setup - in this case where it is possible right thrust is needed mechanically. I like to describe this as "more right thrust authority."

I also agree about the Collective Torque Compensation of the Vbar. If the default value (22) is increased it will feed more right-thrust (clockwise rotation) as collective input increases, thus counteracting the main rotor's torque.

I agree and can tell you from experience the 115mm tail blades work very well with authority, but I doubt it is needed on the Synergy N9.

I'm interested to read your post with results after you first try mechanical right thrust, and then if needed with adjusted collective torque compensation on the Vbar. Good luck.
_Sam B_
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05-03-2011 07:21 AM  10 years ago
uragano47812

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Friuli, Italy

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Take a look to this video.

http://www.youtube.com/user/Fredrik.../16/xk8A6fqEHJk

I always use P and I gain @ 75 ehe acceleration instead depends on your feeling if 75 is too quick try 65.

The precomp value 10 for collective and 3 for cyclic are a good start. you have to do some pitch pump in flight for test the precomp value for collective and some aileron and elevator flips for cyclic precomp. if tail is solid than you are ok. If the tail goes to right during the tests than you have too much precomp so reduce a little.

Remember that the jive has an aggressive gov mode so some little tail kicks are normal (even more with a very powerful motor).

For exemple i like a lot the vstabi gov because i have no kicks.
Compass 7HV Vstabi - Mini Protos MSH Brain - Trex 600 EFL Mini Vstabi
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05-03-2011 08:09 AM  10 years ago
alchemist

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Auckland,New Zealand

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Just for comparison try a flat throttle curve, sounds like it could be related to the gov.
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05-03-2011 08:49 AM  10 years ago
ChristianM

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Oslo, Norway

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When I do a collective punch on my E9 my tail will kick over a foot to the right after a moment the tail will fix its shelf.
This statement indicates that for a brief moment your TR system is running out of power, i.e. it can't hold the tail. Since the VBar brings the tail back to the correct position then it knows where the tail is commanded to be but is unable to hold it there. Since you are running an electric then it provides an enormous amount of torque instantaneous (more or less) so if your TR power is marginal then it will let go like you describe. There are a few things that you can do to deal with it (I am assuming that you have setup your VBar correctly):
  1. Larger tail rotor blades - This will increase the available power from the TR and the additional power will likely enable the TR to hold.
  2. Stronger servo - Will allow the TR to reach the commanded position faster when under high loads
  3. Use "Chinese weights" on the TR grips - This will reduce the load on the TR servo and essentially allow it to operate faster thus improving performance.
To comment on the last two items, as you approach the maximum deflection on the TR it will push back with quite a large force on the TR servo if you do not use "Chinese weight" on the TR grips (do a search for this simple mod). The Chinese weight will counter balance the weight of TR grip arm and the TR blade when it is spinning. You can test this by removing the head assembly on your heli, disconnecting the push rod for the TR and spooling up your heli while securely holding on to the tail boom (or better yet securing it to something). You can then deflect the TR and feel how much force is developed in the push rod. The Futaba 251 is fast but not that strong so when you hammer the collective the TR has to move very quickly towards the extreme to hold it is may not be able to move the last bit fast enough. Even if you increase the TR blades then the Chinese weight mod will improve the TR performace sice it will reduce the load on the servo.

If this is the issue then adding Torque Compensation in the VBar setup will reduce the symptoms but it can not eliminate it.

Hope this helps.

Christian
Burn fuel, be happy
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05-03-2011 12:11 PM  10 years ago
bmw576

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Traverse city MI USA

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Thank you everyone for all you advice. The tail kicks to the right I have added about 3 degrees to the tail trying to correct it. I was talking to Matt from his experience the problem is with the governor. I hope the weather will hold out and I will be able to get it out to the field today.

I am running a flat throttle curve.
Thanks again
I will keep you posted with update

https://rc.runryder.com/t644314p1/
Team Synergy, Synergy E5, E7, E9, N5c and N7
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05-03-2011 06:10 PM  10 years ago
MrMel

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Gotland

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If that does not solve it drop me a PM (will need to see your log and vbr file)Gone fishing..or hunting..or something
My site: http://heli.dacsa.net - VBar videos and more
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05-05-2011 01:11 AM  10 years ago
bmw576

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Traverse city MI USA

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I think I have the problem resoled. I was working with the setting in the pre comp. Mrmel video was a great help. I won’t know for sure until I replace my main gear. I broke some teeth off in testing I guess that’s what I get when running @ 10 hp. I will have a new one installed by the weekend and will update then.
Thank you for all your help
Team Synergy, Synergy E5, E7, E9, N5c and N7
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05-05-2011 06:39 AM  10 years ago
MrMel

rrProfessor

Gotland

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IF precomp is wrong in 5.1 something more is wrong as well, (only way to get precomp wrong), most common is that you start with swapping servo-cable 2 & 3 and then try to "fix" that problem by some setting, which is not possible.
Check for sample the step "Sensor mounting direction", does that match your physical mounting? If not, time to re-do the setup, it will fly much better.
Gone fishing..or hunting..or something
My site: http://heli.dacsa.net - VBar videos and more
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05-11-2011 12:29 AM  10 years ago
bmw576

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Traverse city MI USA

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I just got back from the field and have great news. I have fixed the tail kick problem. All I need to do is move my tail servo ball out from 14mm to 17.5mm. The tail holds great. Who would have guess it be that simple.
Thank you all for your suggestions
Branden
Team Synergy, Synergy E5, E7, E9, N5c and N7
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05-11-2011 04:58 AM  10 years ago
Sam2b

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Tacoma, WA

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Ah, good job! As you have decreasing the resolution will make for a faster acting tail assembly. I just hope you reprogrammed your endpoints to prevent binding._Sam B_
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05-11-2011 11:20 AM  10 years ago
bmw576

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Traverse city MI USA

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Yes I did you have to love how EZ it is to make changes to the V-bar.Team Synergy, Synergy E5, E7, E9, N5c and N7
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