ThunderTiger X50B setup help for ball link spacing.

[Rob43]

Very much better! Thanks!!!

[johnbs8]

ok im getting confused here. so using the FBL bellcranks at 28mm and using a 1:1 on the servo horns to mach(28mm) your able to get the full resolution needed for cyclic? but this is with the GT5? what about with other FBL units like the beast? like i said before i have a B kit and using the stock cranks 1:1 with the beast X and there is plenty of cyclic throw.
so are what are we trying to achieve here? are you guys just trying to get the max throw that is stated this machine can get? how does it make a difference? i love learning about this stuff!! love helis TY John

[brianapp]

I have been looking over this thread and am trying to figure out why the bell cranks are larger for the FBL head. If the ratio is kept 1:1 it would make no difference. The same amount of angular movement in the servo output shaft would produce the same angular movement in the bell crank whether they are 23mm, 28mm or 50mm. If a ratio other than 1:1 is to be used the balls on the servo wheel should not be inline with each other and the output shaft or the bell crank should be offset (like they do in the mmcp raptor's aileron). This would reduce angular movement of the bell crank for the same angular movement of the servo wheel. Is that the reason? Is this done to allow the FBL unit to go to %100 ATV without exceeding the recommended blade angles (14/14) or bind the swash?

Either way it would be nice to have it documented somewhere so we would know what we are trying to achieve.

[johnbs8]

im going to assume, cuz im still learning..., that 1:1 is, both controll rods are paralel to each other where the balls on the bell crank 28mm apart are the same distance as the servo balls on the horn are 28mm? that correct?

[gwright]

with the flybarless conversion the movement from swash to blade grips is greater, therefore the new (longer) bellcranks are included. With the GT5 to get optimum resolution I found 8mm servo arms to be appropriate, hence the CAD work to quickly determine what the "offset" needs to be on the servo wheel, hence the drawings above to give folks a quick jig to drill those holes in the servo wheels accurately. Don't worry about having "enough" mov ement,..this allows something around 14 or 15 each way on collective and slightly less on cyclic,.. with GT5 set at the max collective number of 127 .With my original 11.5mm servo spacing I had something ridiculous like 24+ each way on collective,.. hence the repositioning of the balls closer in to achieve much less than 1 to 1 ratio

[brianapp]

The needed reduction in swash movement makes sense and that is what larger bell cranks would do. If that is what thunder tiger is going for it would be nice if they included a servo wheel template or made mention of the measurements needed for no binding. It looks like you figured it out at 8mm out and .8mm back. A template would have been nice as part of the conversion kit anyway.

[cbcelectech]

I ended up having to use relatively narrow ball spacing on my X50 flybarless. I couldn't use the round servo horn with my Align servos due to interference with the canopy post other freaks already pointed out.

I went with the six arm horn that comes with my DS610s on the last hole out. I had to cut off the two inner arms to keep them from rubbing on the linkages at the extreme servo throws.

Next problem I ran into was during the setup of my Spektrum AR7110BX. When setting up parameter J under the setup menu (cyclic pitch geometry), I could not get the light to stay blue at 6* of cyclic pitch. I put all the cyclic balls one hole closer to the center and I could just get the light to stay blue. I'm not exactly sure if this is important or not, but I didn't want to take any chances.

I ended up with a ball spacing of about 21 mm and my electronics and mechanical setup was happy with this.

[CSpaced]

Originally Posted by cbcelectech

Next problem I ran into was during the setup of my Spektrum AR7110BX. When setting up parameter J under the setup menu (cyclic pitch geometry), I could not get the light to stay blue at 6* of cyclic pitch. I put all the cyclic balls one hole closer to the center and I could just get the light to stay blue. I'm not exactly sure if this is important or not, but I didn't want to take any chances.

I ended up with a ball spacing of about 21 mm and my electronics and mechanical setup was happy with this.

Mechanically your pushrods will bind at extreme throws. You can view this by popping one of the links off and applying full throw, then hold the loose ball link over the servo horn to see how far off it is.

To correct this, you need to offset the holes on the servo horn as described by Gary earlier in the thread, which I posted below with the pic.

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.

[TomC]

Originally Posted by CSpaced

Mechanically your pushrods will bind at extreme throws. You can view this by popping one of the links off and applying full throw, then hold the loose ball link over the servo horn to see how far off it is.

To correct this, you need to offset the holes on the servo horn as described by Gary earlier in the thread, which I posted below with the pic.

Not very useful thead imho. Mainly just one guy telling you that unless your servo spacing to bellcrank spacing is not perfectly 1:1 (~28mm ball to ball spacing in our fbl case) you will get binding in the extreme ends of servo travel. then he shows you that you can offset the servo ball locations to account for this, lol! What he fails to show is that we do not operate at these extreme servo travel ends.

In my case bringing the servo ball spacing into ~22-23mm does not cause any binding within the servos operating travels and in fact bringing the servo balls in a bit actually improves the servo resolution imho. I am using a helicommand hc3sx which is pretty picky on geometry. I did not have any problems setting it up and it fly's great. Running +/-13.5 deg collective and 10 deg cyclic btw.

Cheers,
TomC