General subtrim setup

[transpro61181]

Hello, I have a Trex 450 pro 3gx with a Spektrum Dx7s and want to know if the 3gx has to be in dir mode to adjust subtrim/90ing of servos....seems to be a lot of different opinions on that one. Also I have to drop the aileron servo travel down to 100%/92% percent because it seems to want to outrun all the other servos slightly towards the end of its travel. With that travel setting I get a PERFECTLY LEVEL SWASH THROUGH THE FULL RANGE OF TRAVEL(+13TO-13). my subtrim settings to acheive PERFECT 90 are Elv=25U Pit=15- Ail=6L.

 

[Tony]

YES! You MUST be in DIR mode to adjust the subtrim and 90 the servos, set pitch and so on. There is just no way to do it accurately with the gyros working. And I have heard of people having to do that to the endpoints, but I have not done it. I never to full stick anyway so don't worry about it. But if it works for you, great. We need video of it flying now

 

[Slobberdog]

I would seriously not use any end point adjustment with the 3gx what so ever.

I done it on my 500 DFC build a couple of weeks ago, and this caused the heli to tip over and blade strike the ground, see this video of the swash interaction due to EPA, see post 59

New 500 Pro DFC - Page 6


the 3Gx does not like the use of End Point Adjustment, you can use swashmix to do the same task and its ok to do that with the 3Gx

 

[transpro61181]

My bad Tony I didnt explain it that well..the question I meant to ask is do you have to do the entire dir setup all in one session for the 3gx to learn how much subtrim you have to give the servos to 90 them. I know you have to be in dir to set it up just does it all have to be done at one time. My main issue im having now is servo interaction, the aileron is slightly outrunning the other two servos. its a very VERY small amount towards the end of travel. Trust me im dying to fly it but i crashed it almost a year ago due to improper setup and almost abandoned the hobby but im no quitter sir have decided to get back into it and I think I am just being over critical about setting it up to avoid another crash. I have been practicing extensively on phoenix 5 and pretty much got the motions down.

 

[Tony]

There is no need to do it all in one sitting. You can go back into DIR mode any time you want and make adjustments. The rudder is the only menu that you have to do all at once, and you have a 10 second time limit on each setting. It sucks sometimes.

 

[transpro61181]

what do you recommend I do about this aileron issue?

- - - Updated - - -

i got the swash to work perfect by dropping the travel down to "100% 92%" but I have so many mixed opinions about that one

 

[Tony]

What I would do is set them to 100/100 and do a test hover. If you are running 3.1, then you are going ot want to get off the ground pretty quick as it likes to tip. But once in teh air, should be stable as it can get. If you notice as you ascend and descend that the helicopter is not staying level, then you can start to adjust some settings. but I would start with teh settings in the gyro such as elevator pre-comp. But we will get into that later on if this is an issue.

 

[transpro61181]

Ill take your advice on that one. Thanks for your help Tony! BTW im running 4.0

 

[Tony]

Cool. 4.0 is great on the ground from what I have found with the limited time I flew it. Because of hte tail issues, I reverted back to 3.1, but still have not flown it much lol. When you get it in the air, and you are comfortable with it, give the tail a little flick and see if it snaps back. If it does, then you are having the same issues everyone else is having with it. However, if you snap the tail and it stays turned, then you have a rare case of it working like it should lol.

 

[transpro61181]

I think im gonna go back to 3.1 because ever since i upgraded to 4.0 I have noticed my servos randomly twitch when it sits idle on the bench