Some help please, it's doing my head in!

[psilo]

So, last night was finishing up the EXI built. Really happy with how it was going, went to setup the head (CopterX head). Got the throws just about perfect so wasn't binding at bottom andwas just off the bushing at top pitch. Swash all level, moved on to getting pitch sorted.

Maybe it was because I was tired but I cannot get the pitch range mechanically right. With zero pitch I have +9.5 at full pitch and -12 at full negative. I chased it up and down and finally gave up at 3.30am when I was just too tired to think.

Just about to sit down again and have another look. FYI, I had set all the linkages to the length in the SEV2 manual prior to starting, the washout was level at mid stick, everything looked just as it should except the pitch!

Thanks for any comments, suggestions, criticisms and general laughing and joking about not having good head

[psilo]

Currently in the process of stripping the head down totally and rebuilding. Have got a new pack of linkages so have made all the linkages up again exactly as per the manual's recommended lengths and just starting to put back together. WIll post once that is done and see where I am at then!

[kent83]

Gerd,

It's not much help, but I had the same issue. I crashed the Exi on my maiden flight, broke several plastic linkages in the standard head, and replaced it with CopterX. I got numbers very similar to yours, and got them just a bit better by adjusting both the short and long links on the rocker arms, but it's still not where it should be. I have so many other issues going with my Exi right now, I've left this one for a while. I am using the Exi swash plate though, and I was thinking I should switch that with the CopterX swash at some point, but that shouldn't be the problem, should it?

Sorry I don't have the solution, but I did have the exact same problem.

[psilo]

Thanks Kent for the input. Good to hear it's not just me!! The swash should make no difference as it is what happens above the swash which causes the problem.

Have levelled the swash now and got the travel right so it is not binding on the collar nor on the washout, so just moving up to levelling the washout at mid stick now.

[Grant_beltcp]

Are your servo horns perfectly level? if theyre a fair distance off theres a good chance you will see the pitch range you get.

The other thing, are your endpoints in the TX all at 100%? and subtrims quite low?

If you can't seem to sort it, one way of doing it is upping your swash mix %'s to 100%, and adjusting all your end points to limit servo travel up and down ntill you get the correct pitch ranges.

Also, is your swash being limited at all? I.e, is the washout block hitting the head block to stop it moving further up?

If you take the linkages to the swash off, can you move it higher than the servos are moving it?

[psilo]

Well, I have now got it to +/-11 but with +1 at mid stick!

Grant, All servo horns level and ball is same distance out on horn. Virtuall no subtrim +2 on aileron and +4 on elev. End points all 100%. Swash is on 60%. Swash not being limited, the washout block has about 1mm clearance at the top from the head block. Likewise, no hitting the collar at bottom. Yes, if I take the linkages off I can move it up that extra mm.

To be honest, I am happy now with it as it is. I don't mind having 1 degree at mid and +/-11 at extents, it will do! Just got to get the tail setup and she is ready now. Although, haven't done the chinese tail weight yet, must do that and see how the logictech 2100t/2100g performs prios then!

Damn wind, gonna have to try and set up rate mode in the wind, JOY!

[Ian 777]

Hi Gerd
You can fix it by biasing your end points and slightly increasing swash mix to compensate if you want to get it spot on

[Heli Yea!]

IMO I think you should lengthen the links to the swash a turn and eliminate the 1mm gap between the washout and head blocks then lover your pitch a turn. Then you should get +/-10.5 me thinks!

[psilo]

Chad,

The problem is that if I lengthen the swash links a turn they are then right out on the threads. I did think of that and may take another look but one in particular would be getting to a dangerous length. Also would that actually change it? I would think that lengthening a turn would just add a degree to each postition so -10 +2 +12 then bringing it down at the blades would again give me -11 +1 -11?!

Mike, yep, I could also just use the pitch curves to limit the lower and move the blades down a touch giving me +/-10 with 0 in the middle. Was just trying to get it mechanically spot on.

She flies great anyway so will see how I get on and revisit when I crash next

[Jonnyheli]

Just a thought.

When putting the horns onto the servo. There is either to much right or to much left with 0 subtrim. By putting the horn on with some positive pitch, then subtrimming it back to 0, maybe you will get a tiny bit more throw the other way (Positive) Ths might affect the negative throw but maybe not.

Hope that is clear, I don't think I explained it very well.

-Jonny

[Heli Yea!]

Are your see-saw arms flat with the bottom of the see-saw? If the screws are even with the flybar cage link rods or the tops of the see-saw/see-saw arms are flat it will throw off your pitch range. The bottoms must be flat. Another thing I've found using the stock Tx is to get a perfect mechanical setup you must disobey Bob(about linkage) and use half turns. I have never got it perfect using only full turns as Bob suggests and never had a linkage problem.(Bob is still the man though!) I do regular linkage checks and replace ones I think are loose. So to clear up my first post when I say a turn I actually mean a 1/2 turn.