ThunderTiger X50B setup help for ball link spacing.

[johnbs8]

I am going to see if I can contact someone from the factory team to drill this question, since they don't seem to monitor the nitro forum.

any luck with that Rob?

[Rob43]

I can't see the 28mm vs 23mm making any difference at all, provided both the bellcrank and servo arms are the same at each point. It torque's me a bit that the CNC bellcrank for elevator control in the conversion kit will cause an interference problem with the right side canopy post. Looks like it will run right through it.

[johnbs8]

rob i didnt check full resolution but at half movement on the servo the threaded part of the ball link touched the canopy post and that convinced me to take it off.

[Rob43]

Which bellcranks and servo arm distance resulted in that?

[johnbs8]

the align 6 star horns with the balls 28mm out (3rd hole) and the FBL ele arm.

[NitroAl]

I just put a six point horn on and there is about enough room for a cigarette paper to slide in there. I just cant see the point in increasing the spacing if it was not intended to improve resolution. With the sort of travels you are using at 23mm the binding is minimal if measurable surely?

[johnbs8]

yah no bennefit. stock going back on!!

[Rob43]

I've not built yet. I intended to build FBL from the start. I was thinking, it wouldn't take much to move the canopy posts enough to create some clearance. Like NitroAl is saying, I wonder why this larger spacing is? Chris said earlier that no one seems to know, including the factory pilots. I've also noticed that the Align wheels also use a larger spacing at the servo wheel and bellcranks too. If it's the same at both ends of the push/pull how can it have any effect? ... Unless it's not necessarily intended to use the spacing we're assuming at the servo wheel. I noted in the RC Heli review of the G4 nitro last month, that their setup isn't 1:1....it is still questionable.


Look at pages 52, and 54. The servo arm distance between balls is significantly less than the bellcrank.

[CSpaced]

Originally Posted by Rob43

I noted in the RC Heli review of the G4 nitro last month, that their setup isn't 1:1....it is still questionable.

The G4 doesn't use 1:1 geometry, it has offset bellcranks and includes it's own offest servo horns to match. (see pic)

[Rob43]

Thanks Chris. How is it that we know the X50 is to be 1:1 control? Are there offset servo arms missing from the FBL conversion kit? Please don't take my question wrong...I am just trying to rationalize the design basis. There seems to be a discrepency here somewhere.

Thanks!

[CSpaced]

Originally Posted by NitroAl

Thanks Chris, I'll give it a go at 1:1 and see what sort of numbers I get as I don't see myself getting the sort of numbers listed in the GT5 configuration table for the servo's I have but I guess I wont know if I don't try!

I don't know what numbers you are shooting for, but using the stock bellcrank configuration, 1:1, I was able to get 14 degrees +/-. Should be more than enough for the GT5.

[CSpaced]

Originally Posted by Rob43

Thanks Chris. How is it that we know the X50 is to be 1:1 control? Are there offset servo arms missing from the FBL conversion kit? Please don't take my question wrong...I am just trying to rationalize the design basis. There seems to be a discrepency here somewhere.

Thanks!

The reason we know it to be 1:1 is that the bellcranks (both stock and FBL conversion kit) are not offset, the ball links are inline with each other through the pivot point of the bellcrank. Setting up anything else other than 1:1 will result in the pushrods binding when you give any input.

You can actually see it for yourself pretty easy, just move your ball link out (or in) on your servo horn and just loosely hold the ball link over the ball. You can see when you give it input that the loose ball link won't travel with the ball to the extremes.

The only thing that is different on the FBL bellcranks is the spacing of the ball links, but they still require a 1:1 setup. Still not sure what the reason for the different spacing is though....

[NitroAl]

Well I have tried all sorts of configurations! With the 16mm centers it was as Chris said with the link that i took off the ball over taking the ball at full collective + full elevator and was worst (naturally) on the elevator servo!
With 1:1 I had to turn the servo travel in the GT5 down to the minimum of 50 to get close to the 6 to 8deg (actual 8.4) cyclic required and then turn up the pitch in the swashplate menu to 127 (maximum) plus turn up the pitch end points in my radio to 137 in order to get 13.5deg pitch.
At 23mm with the FBL cranks the servo travel is up to 70 @ 8deg cyclic, pitch is 125 with TX back to 100 @ 13.5deg collective and although binding will still be there it can't be seen with the naked eye!
I would be interested to see how VBar deals with 1:1 as it is easy to compare it to other configurations with it's simple slider setup!

[gwright]

attached is a jig I made in CAD after drawing the servo to bellcrank distances and ratios. When converting to flybarless and using the GT5 I had extreme pitch throws which required reducing the ranges for collective in the GT5 to 74 on the unit and cyclic ranges to around half in the radio. Being as anal as I am about these things I wanted to get the numbers higher as the GT5 was using around 18/18 of possible cyclic range for corrections, although it was reduced to around 8/8 for pilot input from the radio ATV's. With the GT5 you set collective range in the unit (default 100, max is 127 and I was greatly reduced to get around 14/14 collective). The cyclic range is set with transmitter ATVs and they were down around half. After putting everything in CAD I needed 8mmm servo arm length with the flybarless bellcranks being 28mm (if I remember the numbers, it's been a while <G>). This is a pretty large reduction from the 11.5mm spacing I was using with the stock bellcranks and flybar head, but I thought all I have to lose is a little time and 3 servo wheels, so I proceeded. I put all the required "offset" in the servo arm, which actually only ended up at 0.81mm offset (used the reciprocal angle from the pushrod to bellcrank in order to position the servo wheel balls). This resulted in increasing the gt5 collective to the max of 127 to achieve 14/14 collective, thus regaining all the possible resolution, and cyclic ATV's vastly increased.. Difference was night and day. I put a little 20mm scale on the drawing so you can experiment with print scaling to get them the right size in whatever application you print it from.

[gwright]

oops,.. wouldn't allow an rtf file. put it in paint and saved as jpg

[Rob43]

Thanks for the information. Chris. After this on-line discussion last night, I carefully examined the instruction sheet included in the FBL conversion kit, #3925 (for X50) and note that for the belcranks, it shows to re-use the existing belcranks as denoted by an asterisk (*). It's not clear to me what purpose the 28mm belcranks will serve unless they are used for some reason on the X50F when it's released. Whatever. 23mm it is.

[CSpaced]

Originally Posted by gwright

attached is a jig I made in CAD after drawing the servo to bellcrank distances and ratios. When converting to flybarless and using the GT5 I had extreme pitch throws which required reducing the ranges for collective in the GT5 to 74 on the unit and cyclic ranges to around half in the radio. Being as anal as I am about these things I wanted to get the numbers higher as the GT5 was using around 18/18 of possible cyclic range for corrections, although it was reduced to around 8/8 for pilot input from the radio ATV's. With the GT5 you set collective range in the unit (default 100, max is 127 and I was greatly reduced to get around 14/14 collective). The cyclic range is set with transmitter ATVs and they were down around half. After putting everything in CAD I needed 8mmm servo arm length with the flybarless bellcranks being 28mm (if I remember the numbers, it's been a while <G>). This is a pretty large reduction from the 11.5mm spacing I was using with the stock bellcranks and flybar head, but I thought all I have to lose is a little time and 3 servo wheels, so I proceeded. I put all the required "offset" in the servo arm, which actually only ended up at 0.81mm offset (used the reciprocal angle from the pushrod to bellcrank in order to position the servo wheel balls). This resulted in increasing the gt5 collective to the max of 127 to achieve 14/14 collective, thus regaining all the possible resolution, and cyclic ATV's vastly increased.. Difference was night and day. I put a little 20mm scale on the drawing so you can experiment with print scaling to get them the right size in whatever application you print it from.

Nice job, and thanks for posting the file.

Originally Posted by Rob43

Thanks for the information. Chris. After this on-line discussion last night, I carefully examined the instruction sheet included in the FBL conversion kit, #3925 (for X50) and note that for the belcranks, it shows to re-use the existing belcranks as denoted by an asterisk (*). It's not clear to me what purpose the 28mm belcranks will serve unless they are used for some reason on the X50F when it's released. Whatever. 23mm it is.

That's interesting, I'll have to take another glance at the manual (been a while!).

[Rob43]

Well, hold that thought. The FBL instructions do denote these parts with the asterisk (*)... however,

From PM with Gary this morning, he found that when OFFSETTING the the ball spacing on the servo horn by a mere .8mm and setting them at 8mm apart, that the 28mm belcranks produce nearly perfect throws for FBL setup in the software and good ATV values.

How's that for being in the dark - there is nothing in the FBL instructions to tell anyone about this...

This will be my strategy for the build with Vbar. Will report back when I get there.

[CSpaced]

Originally Posted by Rob43

From PM with Gary this morning, he found that when OFFSETTING the the ball spacing on the servo horn by a mere .8mm and setting them at 8mm apart, that the 28mm belcranks produce nearly perfect throws for FBL setup in the software and good ATV values.

That's right, Gary already posted a drawing above to aid in locating the holes for the offset.

[gwright]

PDF might be better