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HomeAircraftHelicopterFlybarless Rotor Head SystemsAlign 3G › Swash not level at high and low stick
09-12-2015 03:58 AM  33 months agoPost 1
Ahile

rrNovice

Apple Creek, OH

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I have a Trex 700e DFC with 3GX w/ version 5.0 controlled with a DX9. I have been flying it for quite a while now and flies great except I notice that it wants to move forward at a hover. I was looking at it this evening on the bench and realized that the swash doesn't move up and down level like I think it should. At mid stick, 50% pitch, the swash is level. With the collective at full positive, the swash is no longer level, it is tilted forward. With collective at full negative, the swash is tilted back. This explains why it always wants to move forward in a hover. On the radio, all travel ATV are 100%. Subtrims are: ail 7, ele 60, pit o. Is the ELE subtrim at 60 causing the problem? I have gone through the setup again and everything looks good. Any ideas?

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09-12-2015 10:47 PM  33 months agoPost 2
JuanRodriguez

rrProfessor

The Villages, Florida

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Ideally, you should adjust your servo to swash push rods so that the length of the three rods is the same and so that the swash plate remains level throughout the entire pitch range ..... And again "ideally" all of that should happen without the use of sub trim ...... But then reality sets in ....😄. I think the most important part is to get the three push rods the same length....then use small amounts of sub trim to achieve perfection.....

There a a lot of folks out there much smarter than me that can give you a better explanation on the "how to" and maybe provide a good YouTube video outlining the process .....

Me ?, I just strive for "good enough" .....😜

Been there, done that and old enough to know better.....

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09-13-2015 03:58 AM  33 months agoPost 3
R/C Speed Nut

rrVeteran

Galesburg, Michigan USA

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I think your issue is the collective to elevator compensation.
Zero out that through the PC program.


Mike

Funky Chicken?!!..........I thought this was how you do a piro flip!!

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09-13-2015 04:07 AM  33 months agoPost 4
DemetriusUSN

rrVeteran

Virginia Beach, Va USA

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60 is way to much for sub trim,anything over 15-20 clicks means you have to go back to a mechanical setup at mid stick. Clear all sub trims, use a swash leveling tool, put it at mid stick and mechanically get it there first or as close ad you possibly can. You want to use as little subtrim as you can,with a fbl unit I don't use any. Do start over, mechanically get it as close at you can with a swash tool on the swash and you should be good.

Minicopter Diabolo 800, Minicopter Triabolo 700, Minicopter Diabolo 700, Minicopter 550,Compass 6hvu, Devil 380

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09-14-2015 02:10 AM  33 months agoPost 5
R/C Speed Nut

rrVeteran

Galesburg, Michigan USA

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While I agree that ideally you want to eliminate as much subtrim as possible, I don't think that it's causing his issue.
If it was a subtrim issue he would see reduced servo travel in one direction, not over travel in both directions.
In all of my 3gx installations I had to zero out the collective to elevator compensation to eliminate this very same issue.


Mike

Funky Chicken?!!..........I thought this was how you do a piro flip!!

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09-15-2015 03:15 AM  33 months agoPost 6
Ahile

rrNovice

Apple Creek, OH

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Found the collective to elevator pitch compensation to be at 50%. Changed to "0". Looks like it has taken care of it. Hope to try it later this week. Thanks guys.

Adam

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09-21-2015 05:02 PM  33 months agoPost 7
dkshema

rrMaster

Cedar Rapids, IA

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From a hover, apply full collective and climb straight up. The tail should not drop as you do. If the tail drops as the heli climbs, increase the tail to elevator compensation value. If the tail rises, decrease the value. Adjust the value so the heli remains level during a full collective climb out.

I suspect the setting of "0" is not what you want.

The behavior of the head with the heli at rest does not reflect how the heli will behave in flight. The gyros need to sense movement, something lacking with the chopper sitting motionless on the ground.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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