Vbar: reversing servo direction changes center position!?

[bleomycin]

I just finished leveling my swash making it absolutely perfect mechanically with the linkages and the fblrotors swash leveling tool. After i finished i noticed that some of the servo's were setup wrong in the vbar software and needed to be reversed. Once i hit reverse all of my servo arms went from being at perfect 90 to completely out of whack! Reversing the servo in software shouldn't change the center position of the servo, should it? Do i have to remove all of the arms now and find the perfect spot once again or is this some software problem i don't understand? It's taking the maximum trim allowed in the vbar software on every servo to get them back to being perfectly level, doing that seems like a bad idea to me? Thanks!

[jb31d]

I am not a Vbar expert, but I would say you need to ensure your servos are throwing the correct direction first, before you start worrying about leveling the swash.  I think that's actually the first step in the setup wizard as well.  Once you have them throwing in the correct orientation, then you can make sure you have the horns on at 90*.  You should only have to use the slightest amount of subtrim in the Vbar setup wizard in order to get everything level, especially if you bought Ralph's titanium pitch links along with your swash tool.

Following Chris' setup videos, I oriented my servos before I placed them on the airframe to make sure I had the horns on as close to 90* as possible, then started the Vbar setup as normal.  I only had to move one of the horns up one or two splines to get it almost perfect, and I only needed about two or three clicks of the mouse on the subtrim swash leveling step to get the plate level.

Make sure you are doing all of this at mid stick as well, or it's pointless.  Check out Mr. Mel's setup videos if you haven't done so already.

[Chris Sexton]

Setting servo centers and travel direction has to be done in a specific order. The setup tabs are layout in order on purpose.  The reason the arms moved is because the trims you used to level the swash are like sub trim under a FB setup. When you changed direction of travel the direction of the trims also moved. 

Here is the order you need to follow on the first few tabs to get everything moving  right:
1. On the tx travel screen (tab3 I believe)
- first set tx directions. Make sure when you give it input the vbar screen moves that input the same way. If one channel is backwards here then you reverse the servo channel in tx.
- once tx directions are right then center the sticks and use tx sub trim to get 0 on all of the vbar sliders
- once center is found check that when you give input to full (ie full right aileron) the vbar screen shows 100%. Use servo travel to get 100+\-  on all of the control inputs including pitch.
- you are done with the tx settings for servos. From now on changes are made in the vbar menus with one exception depending on what version, express or pro.
2. On the next tab it asks you the orientation of the vbar sensor. This is important for gyro compensation.
3. On the next tab it asks you about servo directions. This is where you make sure that all the servo are actually moving in the right direction. If an individual servo is reversed, reverse it on the vbar screen not in the tx.
4. Servo trim. On this tab is where you give each servo a little trim to fine tune the swash level.
- on this screen the servos are automatically moved to their reference positions and the collective input on the tx is ignored.
- i strongly recommend you get the swash as close to mechanically level as possible. I.E. adjusting the swash links until the swash is as close to perfect as it can be. You can make trim adjustments electronically but a good mechanical setup is critical for Optimum performance.
- If you are running the professional version of the software, you can press the  Expert set up button on the servo trim page and level the swashplate at both high travel and low travel. This help make sure it doesn't pull one way or another on hard pitch inputs.

If you follow the steps in this order, you will now have all of your servos traveling in the right direction and a level swash.

The rest of the set up varies greatly depending on whether you are using express or professional.

I strongly recommend watch Bert Kamerrer and the guys from Smack Talk's vbar setup video. Best $6 you can spend of you want to fully understand vbar setup. Mr Mel has a free video but he doesn't cover it in as easy to understand manor as Bert. If you are more technically orientated mr Mel's videos will help a lot.

Let me know if you have any questions. I am always willing to talk over the phone if needed.

[Chris Sexton]

Here is the link to the VBar video I was referring to. I can't stress how much this video helped me!

http://www.smacktalkrc.com/archives/524

[Chris Sexton]

I just re-read my longer post, wow typing all that out on my iPhone sucked If any of that was overly hard to follow let me know. I tend to be a bit technical in my writings.

[steffgiguere]

Chris is right, if after doing all this as explained still does not work then try maybe you  reversed servos 2 and 3 (aileron servos) in the V-Bar.

[RichL]

Also make sure you don't have any sub-trim set in you radio.

Rich

[Chris Sexton]

Also make sure you don't have any sub-trim set in you radio.

Rich

Actually on vbar radio sub trim is used on the tx setup menu to get centers calibrated.

[RichL]

Chris, I was speaking of sub-trim beyond what is required to get V-Bar and the radio to agree on where center stick is but, your point is well taken.  However as noted in your setup instructions there is a specific order that V-Bar needs to be setup.  If you calibrate the radio centers with the servos (centering frequencies) reversed then the centers will be off by the amount of the change you have already entered for the correction plus the original error in servo spline or mechanical alignment.

Rich

[Greg Jackson]

Are you using the express or Pro software?  Probably doesn't matter but just asking in case it may help others diagnose the problem.  Hope you get things worked out soon.