Few niggley problems setting swash and pitch

[Pj1969]

So I put my trex 500 in on Sunday and she's all rebuilt and just going through final set up, but I'm having a few teething problems setting pitch etc. as I had to replace a link, I have replaced all 3 links to the swash and set them to 18mm which is what the manual says and the blades links, 36mm. Using a digital pitch gauge I can get 0.00-0.01 on one blade and 0.00 0.01 /.2 on the other, but here's my discrepancy, at low stick I'm getting 10.7-8 and high stick 11.8-9 or there or there about on both blades. I've tried adjusting swash to lower it by one tun on each link, but still can't get it the same. I've gone into MSH brain software, but I can't adjust pitch down any more, any one got any ideas what I can try? Obv I want to get blades to 0.00 and I fly at -10/+10* so it's kinda frustrating to say the least. My pitch curves are linear and set at mid stick to 0 blades.

[Mikej]

Lowering the swash would be the best bet, but if you aren't able to then you could raise your lower point on the Pitch curve until the max neg equals your max positive

[Pj1969]

Cheers mike, think it's all done in the brain software, I'll have a look later when my head isn't frazzled anymore lol.

[Mark_T]

If you are aiming for -10 to +10 then you are probably close enough already as mechanically you already have a greater range than that so you should be able to alter the max and min pitch in the FBL setup (I'm not familiar with the Brain so can't explain exactly where).

Personally I aim to get the mechanical set-up as near perfect as possible so I'd be looking to adjust the height of the swash so it was exactly in the middle of the range of travel when the servo horns were at 90 degrees. Once that part is right you then adjust the links to the blade grips to get zero again at mid stick.

Can't get it exactly with every heli unless all three links from the servo to the swash are adjustable, but if they are it should not be too hard to get this right.

That said, you are only half a degree out so I wouldn't be overly concerned.

If you really want to get it closer then one short-cut given where you are now (assuming mid-stick puts the servo horns at 90 degrees) would be to adjust the blades links so you get -0.5 degrees at mid-stick then adjust the links from the servos to the swash to bring the blade angle at mid-stick back to zero. That should even up the range.

[Pj1969]

If you are aiming for -10 to +10 then you are probably close enough already as mechanically you already have a greater range than that so you should be able to alter the max and min pitch in the FBL setup (I'm not familiar with the Brain so can't explain exactly where).

Personally I aim to get the mechanical set-up as near perfect as possible so I'd be looking to adjust the height of the swash so it was exactly in the middle of the range of travel when the servo horns were at 90 degrees. Once that part is right you then adjust the links to the blade grips to get zero again at mid stick.

Can't get it exactly with every heli unless all three links from the servo to the swash are adjustable, but if they are it should not be too hard to get this right.

That said, you are only half a degree out so I wouldn't be overly concerned.

If you really want to get it closer then one short-cut given where you are now (assuming mid-stick puts the servo horns at 90 degrees) would be to adjust the blades links so you get -0.5 degrees at mid-stick then adjust the links from the servos to the swash to bring the blade angle at mid-stick back to zero. That should even up the range.

Thanks Mark, yeah all servo's were 90 and I've tried adjusting links, but they either go over or under what I'm aiming for. I will look into fine tuning in the software, but I'm new to the MSH so just getting to know where things are. I no I'm not that far off, but when looking at a digital gauge, your head tends to want all reading to be exact, or is that the OCD kicking in lol

[Mark_T]

I wouldn't worry too much, you are only 0.5 of a degree out, if one turn is too much then you are as close as you can get.

Just adjust max/min pitch during the MSH setup to get the range you want.

... and yes, that is the OCD, but I'm right there alongside you pm that one, just take comfort in the +/-10 you will see when you get the MSH configured right

[Mikej]

I meant to say that - you're getting into areas where 5 years ago (before the arrival of digital pitch gauges) you would have lined it up by eye and said "job done" by now. I bet you won't notice it in flight .....

[Pj1969]

THis is right mate?, I should of used my other gauge and level, so much for technology lol