3G pitch adjustment question

[zci_zr]

I have just setup Trex 500, but I could get the pitch in correct position. I have trimmed pitch to 0 degree when throttle/pitch at half stick， and then try use swash mix to adjust pitch to correct range (+12 degree ~~ -12 degree). Here is the problem, I can adjust positive pitch to 12 degree and then my negative pitch only at -10.5 degree. So what I did is increase the swash mix to keep positive pitch at about 13 degree and then my negative pitch would be just under -12 degree.

My question is would that be ok if I keep like this or should I adjust travel adjustment on my Tx to limit positive pitch at +12 degree. Or may be some other alternative way I can make this right.

Many thanks

Rui

[Vic.P]

After adjusting the overall travel of the swash with the swash mix, alter your pitch curves to get the limit of +12 and -12.

[zci_zr]

After adjusting the overall travel of the swash with the swash mix, alter your pitch curves to get the limit of +12 and -12.

Hi Thank you very much for your reply.

I am using DSX9 too, do you means after adjusting the "Swash Mix" in Tx, i should alter (reduce the CH-6 traveling limited) in the "TRVL ADJ." to limit of my positive pitch to +12 degree?

Thanks again.

[Vic.P]

Hi Thank you very much for your reply.

I am using DSX9 too, do you means after adjusting the "Swash Mix" in Tx, i should alter (reduce the CH-6 traveling limited) in the "TRVL ADJ." to limit of my positive pitch to +12 degree?

Thanks again.

No, don't reduce the travel adjust to change pitch values, having established a saticfatory collective pitch range using swash mix that will allow the + and - pitches specified, you then need to use a pitch guage to adjust the pitch curves for all flight phases, normal, idle 1, idle2 until each reads +12 degrees at top stick and you may want to have +13 to +14 degrees for Throttle Hold curve for autorotations. Then adjust for normal, -2 degrees and then idle 1, idle 2 and Hold -12 degrees at bottom stick.

Mid stick for idle 1, idle 2 and Hold should be 0 degrees and for normal, around +5 to +6 degrees.

[zci_zr]

No, don't reduce the travel adjust to change pitch values, having established a saticfatory collective pitch range using swash mix that will allow the + and - pitches specified, you then need to use a pitch guage to adjust the pitch curves for all flight phases, normal, idle 1, idle2 until each reads +12 degrees at top stick and you may want to have +13 to +14 degrees for Throttle Hold curve for autorotations. Then adjust for normal, -2 degrees and then idle 1, idle 2 and Hold -12 degrees at bottom stick.

Mid stick for idle 1, idle 2 and Hold should be 0 degrees and for normal, around +5 to +6 degrees.

Hi, thanks again for your reply.

I am very sorry for my ignorance, due to I am very new to this area. Do you mean I should reduce the Pitch Curve Highest point to reduce the highest pitch degree?

For example, If I am have negative -12 pitch, with positive +13.5 degree pitch, what I should do next is reduce Pitch Curve "point -H" (highest point) from 100% to (for example) 90% to reduce the highest pitch degree (from +13.5) to +12 ? Am I understanding your point correctly?

Many thanks again for you time.

Rui

[Gingerr6]

Adjust the links to the swash this will bring the pitch in line then adjust the swash mix to achieve the desired pitch

[zci_zr]

Adjust the links to the swash this will bring the pitch in line then adjust the swash mix to achieve the desired pitch

Hi:

Thanks for you reply.

If I don't understanding wrong, do you means adjust (shorter) the three linkages in between cyclic servo arm and swash plate. Is this same effect (result) as I am alter three cyclic servo arm sub trim to lower position simultaneously (in same value)?

What I have done before is: I have shorter the three linkages between cyclic servo and swash plate, but when I try adjust 0 degree pitch when my throttle at have half stick, I have to longer the two linkages between Main Rotor Holder. The result (problem appeared) was same as I mentioned top of this thread.

Please help.

Kind regards

Rui

[Gingerr6]

That is what I am suggesting yes. You should not have any trims on to get the 0 at mid stick. All adjustment should be mechanical first.

[zci_zr]

That is what I am suggesting yes. You should not have any trims on to get the 0 at mid stick. All adjustment should be mechanical first.

I got you, may be I have done something wrong before, many thanks, I will try that again tonight!

[Vic.P]

As Gingerr6 says, set up everything mechanicaly first to get your swash plate level but any alterations on the linkages will need to be the same for all three although the linkage lengths should be correct from the instructions if measured carefuly.
Use the sub trims (not the stick trims) to correct any small inaccuracies because servo horns will invariably be slightly out of 90 degrees on at least one of the servos and sometimes rotating the servo horn through 180 degrees on the servo will correct any major difference.
A neat trick if you don't have a swash plate leveling tool can be found here:

[ame]http://www.youtube.com/watch?v=iUAluAxRi4Q[/ame]

With throttle at mid stick, check with a pitch guage to get the blades at 0 degrees using the swash mix pitch percentage (default 60%). once this is at zero you can then check to see if you can get + and - 12 degrees on top and bottom stick.
Now that everything is mechanicaly set for a levelled and centred swash at mid stick 0 you can now set the pitch curves for normal, idle1, idle 2 and Hold in the usual way.

[Mslater]

Hope this helps, its an english translation of the Align video. Details head setup.


[ame=http://www.youtube.com/watch?v=t5sH-_OREJA&feature=related]YouTube - ALIGN T-Rex 3G Flybarless-setting System by LINK-RC[/ame]

[zci_zr]

As Gingerr6 says, set up everything mechanicaly first to get your swash plate level but any alterations on the linkages will need to be the same for all three although the linkage lengths should be correct from the instructions if measured carefuly.
Use the sub trims (not the stick trims) to correct any small inaccuracies because servo horns will invariably be slightly out of 90 degrees on at least one of the servos and sometimes rotating the servo horn through 180 degrees on the servo will correct any major difference.
A neat trick if you don't have a swash plate leveling tool can be found here:

YouTube - Swash plate leveling using a zip tie 450 helicopter

With throttle at mid stick, check with a pitch guage to get the blades at 0 degrees using the swash mix pitch percentage (default 60%). once this is at zero you can then check to see if you can get + and - 12 degrees on top and bottom stick.
Now that everything is mechanicaly set for a levelled and centred swash at mid stick 0 you can now set the pitch curves for normal, idle1, idle 2 and Hold in the usual way.

I will do that, thank you very much!

[zci_zr]

Hope this helps, its an english translation of the Align video. Details head setup.


YouTube - ALIGN T-Rex 3G Flybarless-setting System by LINK-RC

Hi:

Thanks a lot for your help!

Rui

[tourerjim]

I've got the 3G on my 500' if your setup mechanically correct you should have -14 '0' +14 & on cyclic looking down the heli blade pointing you 12degrees.
If you can't seem to achieve this then go through 3G setup once you have then go back in on first step 'throttle mid stock then check you pitch range & adjust linkage being sure swash plate remains level.

[zci_zr]

I've got the 3G on my 500' if your setup mechanically correct you should have -14 '0' +14 & on cyclic looking down the heli blade pointing you 12degrees.
If you can't seem to achieve this then go through 3G setup once you have then go back in on first step 'throttle mid stock then check you pitch range & adjust linkage being sure swash plate remains level.

Hi tourerjim:

Thanks for you reply.

According to Align's recommendation, the cyclic linkage ball should be 13mm away from servo center point, which is second hold away from center of servo arm. However, I found if I turn on max negative pitch, along with max ELE (push forward) and AIL, two of the found servo arm traveling would stop by servo body before the servo arm reach to where is suppose to stop.

Therefor I have moved the linkage ball to the third hold away from center of servo arm (please see the picture below). This would solve the issue of servo body stop servo arm movement, but will result the linkage ball travelling range increase. So I have shorten the three cyclic linkage rod to counteract the linkage ball travelling range increase issue.

Could tell me if what I have done is appropriate?

Many thanks

Rui