450 Swash plate 0 pitch setup on Trex 450 Plus DFC RTF (3GX MR)

[Erfan]

Hi guys!

I have a Trex 450 Plus DFC with the 3GX MR unit.
I have some issues when trying to setup a level swash.

I'm able to do it at midstick, that is at 50 but I cannot seem to get it right and level at 0 and 100, that is low and highstick.
I have watched several videos, they all say the same thing, you level the midstick position, get your server arms correct and then you look at low and highstick and make sure they are OK by adjusting the endpoints.

Doing this does not work since the manual (Trex 450 Plus DFC) says that aileron and elevator endpoints should not be changed in the TX and I cannot do it at the 3GX MR unit. But I have also seen people setting correct endpoints by changing the swash AFR.

From what I have understood the 3GX MR unit does the mixing for it self, so in the TX you choose swash type = 90 degrees even thou it is a 120 degree ccpm and the unit does the mix by it self.
SO when this is done I wont get the swash AFR menu so that I can set the end points for the bad servos so they all become level. If I try to do this with regular end point adjustments it will not help since its already mixed and changing a channel affects 2 or 3 servos together.

So I'm completely lost here, I have read so many articles and watched so many videos but the all are about a "real" 120 ccpm were the TX does the mixing, is there anybody out there with the same heli as I have and the 3GX MR unit which knows how to do the level at low and high stick?

Also this is the RTF version which came with Align T6 transmitter which is a Futaba 6J transmitter, for those of you perhaps having the same.


Thx in advance!

 

[Tony]

I have to ask.

You do have the same servos on the cyclic, right?

Are all of the balls in the servo arms in the same hole?

If all of that is correct, how much is your swash off at low and high stick? A picture or video would help out quite a bit.

 

[Erfan]

I have to ask.

You do have the same servos on the cyclic, right?

Are all of the balls in the servo arms in the same hole?

If all of that is correct, how much is your swash off at low and high stick? A picture or video would help out quite a bit.

Hi Tony!

The servos are all the same, original Align DS415M, all the balls are in the same hole as instructed in the manual.

I have attached some pics, the first one is at middle stick which is all leveled.


The second one is low stick were the Elevator is way off, its too short.


The third is at high stick were the either Elevator is too long or the other 2 are too short.

 

[johnrc]

Just want to say the your servos need to be 90 to the swash this is what i had to do to my heli to get everything level low mid and hi stick it was making me mad at first but then i got it right and no trouble now.

 

[Erfan]

Just want to say the your servos need to be 90 to the swash this is what i had to do to my heli to get everything level low mid and hi stick it was making me mad at first but then i got it right and no trouble now.

Hi John

But it is level to the swash, at least that is from what I can see... Perhaps I need to double check and really make sure but I'm 99% sure I have made sure that the servos are 90 degrees when looking at the main shaft as reference, basically same as the swash.

 

[johnrc]

Just another thing are your links the right mesurement for what is called for in the manual and this is from center to center of the ball links?????????????????

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Can you show me a side view of the frame where the servos are? So i can see them?

 

[Tony]

Okay, that explains things a bit better. The elevator is traveling way too much.

go into your Tx and go into the travel adjustment menu. Check the numbers are high and low stick and make sure they are exactly the same as the aileron and pitch servos.

Align could be doing this as a precompensation as well. Think about it. When a helicopter goes shooting up into the sky, the tail is going to want to drop. You counter this by giving forward cyclic as they are doing. The opposite is true for heading towards the ground. The 3GX (original) has a setting where you can set this at different settings, and the MR may just do it automatically. As long as you are in teh air flying and it feels good, you should be fine. But, if it's wondering fore and aft, then you will need some more setup in the gyro.

Sure wish I knew more about this gyro lol

 

[johnrc]

Tony did you see that the links and rods are not the same lenght these are like the 450 sport i have three different rods !

 

[Tony]

Yes, I did see that. I have a helicopter with this kind of servo setup. All 3 rods are different lengths because the servo are sitting in 3 different positions. That has no bearing on the issue that he is having since he has a flat swash at mid stick.

 

[johnrc]

Hope i didn't step on any ones toes on what i said here?

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Ok i thought it mite sorry

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Is it not true that the swash is to be level in all three position mid hi and low stick on all 450 size helis

 

[Tony]

Read my explanation above for the answer to that question. And if you are worried about "stepping on toes", don't post the comment. simple as that.

 

[Erfan]

Hi guys, happy that all of you want to help!

John, no worries, no toes stepped on here, just glad for all the input.

All three rods have different length, I have made them exactly as the manual says (Align manual so you never know if its right).
Then I have centered the servo and then adjusted some rods 1-2mm in order to get perfect level at 0 pitch.

I hope I have done correctly so far?

Now all videos and articles say that I need to try low and high stick and make sure that they are level at those positions as well, this is were the problem occurs since I cannot do that on this 3gx-mr unit, the manual even says that aileron and elevator endpoints should not be changed in the TX, even if I try nothing happens, only throttle, rudder and pitch will respond. The unit does not have those options either. Although it has travel adjustments for the rudder :s

I have made a video, my first youtube video actualy which will show all the servos at mid, low and high as well as the swash on those positions, perhaps that will make my explanation little bit more clear. The video: Swash plate setup - YouTube

Tony, from what you said I understand that if its OK at middle I should try to fly and see how it feels since the 3gxmr unit will compensate and make the adjustments on the fly?

 

[Tony]

If that elevator servo is in the inner hole, then without adjusting the travel limits, there is not really anything that you can do. To me, in the video, it looked like the elevator servo ball was in the outer hole which would cause this issue. But, if it's not, then I would just see what happens in flight.

If it were my helicopter, I would try to fly it. But, I have been flying for a bit and if you are new to flying, it could end horribly.

 

[Erfan]

Not sure I understand what you mean with the "inner hole", but I think we are talking about the same servo, that is the one attached to the auto ration bracket (think that is what its called), in the video its the servo at right, the left one is pitch and on the other side u will find aileron.

 

[Tony]

There are two holes on teh servo arms. The aileron and pitch servos (by the way, yes, you are correct on the servo placement. The rear servo is the elevator) have the ball in the inner hole, however I could not see the elevator servo arm and the location of that ball.

 

[Erfan]

Ah, I see

They are all the same, they are all in the inner hole.
Perhaps I need to send Align an email and ask how I'm supposed to setup the swash when I cannot change the EPA on my TX.

I have attached a picture which is a page in the manual, look at list item 8 and you will see what they say about EPA. I'm a newbie but from what I have read and seen on videos, it all sounds really weird, that you cannot set those EPA settings with the 3gxmr.

 

[stokke]

One of the servos seem to be out of sync with the two others. I believe it's caused by either too much sub-trim, or poor servo horn placement (or maybe a combination of both).

Please see the guide in my signature for setting up FBL-head (it might not directly apply to your setup, but it's still relevant).

 

[Erfan]

One of the servos seem to be out of sync with the two others. I believe it's caused by either too much sub-trim, or poor servo horn placement (or maybe a combination of both).

Please see the guide in my signature for setting up FBL-head (it might not directly apply to your setup, but it's still relevant).

Nice HowTo Stokke!

I have no sub-trims and the servo arms are completely level to the swash, I saw that you were level to the actual servo casing but I guess your servo placements are linear? Mine have some odd positions as you can see in my video.
But I have made them horizontally level to the swash as the manual says.

One question, you never checked low and high stick 0 pitch in your article, that is the swash being level at not only middle but even the 2 far outs. That's the actual problem I wanted to solve, in the middle I have it level.
So how do you know if yours are leveled at all three positions? Or perhaps I missed when you did that?

 

[Sparse]

I had that problem, To be honest i just added a bit of sub-trim and now I am level through the whole range of travel, However I was not off as much as you are. but ideally yes you would want to be level so as your spooling up your heli is not acting goofy.( tilting to left or right ) I do not think the 3gx and mr are that different one deal with sats and the mr has a built in sat if i am correct. but the set up processe should be the same almost.

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I just read that sheet you posted. do you have dir and stuff with the mr. if you do thats were you would do your sub trims. do not do sub trims during flight. today Im going to my lhs My boy there has been doing helis for quite some time I will get some info for you.

 

[Erfan]

I had that problem, To be honest i just added a bit of sub-trim and now I am level through the whole range of travel, However I was not off as much as you are. but ideally yes you would want to be level so as your spooling up your heli is not acting goofy.( tilting to left or right ) I do not think the 3gx and mr are that different one deal with sats and the mr has a built in sat if i am correct. but the set up processe should be the same almost.

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I just read that sheet you posted. do you have dir and stuff with the mr. if you do thats were you would do your sub trims. do not do sub trims during flight. today Im going to my lhs My boy there has been doing helis for quite some time I will get some info for you.

I guess with "dir" you mean some sort of settings menu?
If so it has really basic ones, I have attached a page from the manual were u can see which settings it has, basiclly I can set the neutral point for all servos and travel for the rudder. Also gain and roll rates, that's it