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cg and balancing!!!!

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Old 09-08-2010, 08:38 PM
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rs7ion
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Default cg and balancing!!!!

I got a 25% Gary ward mx-2 with a dle30 on it. After the first flight we noticed the ailerons were about 3 clicks out. I balanced it side to side. it took 2 oz. on the left wing. and it still flys with 3 to 4 clicks of trim. I checked the pins on the wing root. 3 out of the 4 was the same. the fourth was off by .026. on the back of the right wing. Is that enough to throw it out? any thing else to look for?
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Old 09-08-2010, 09:23 PM
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Default RE: cg and balancing!!!!


ORIGINAL: rs7ion
the fourth was off by .026. on the back of the right wing.
Is that enough to throw it out?
any thing else to look for?

"anything to look for" is a good way to put it.............

Look from the rear of the plane to see if that out of place pin has the two wings set at difference incidences. Expect the difference to be opposite from the way the ailerons look with the trim settings it took to fly level.

And while you're looking, try to see if the wings are warped. If you see warp(s), take them out first. Then look for difference in incidences again.
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Old 09-08-2010, 09:58 PM
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Default RE: cg and balancing!!!!

It can also be the stab, the wing is the place to look first but if you have some levels and an incidence meter then check the back end too. Sometimes things move during the assembly.
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Old 09-24-2010, 05:06 PM
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Default RE: cg and balancing!!!!

Just by looking from the ass of the airplane, you can't tell 1 degree difference, and I've got pretty good eyes. After I put the maiden on Ryan's 30cc MX2, and seen that we were carrying about 3/8" left trim, I knew something was amiss....... I always presume that the incidences are set from the factory. But in this case, it wasn't. I had him go home, and laterally balance it. Brought it back out, and we still carried 3/8" trim. So, knowing what I know about things, I told him that we need to check incidence. He bought a Robart meter, and I took mine over. Checked the right wing, once the airplane was level. 0 all the way out to the tip. Check the left, root showed nearly 1 deg out, and held it the entire way out to the tip, LE high. So, we knocked out the anti rotation blocks in the airplane, hogged bigger holes in the fuse, and then installed new anti rotation blocks, after we set the incidence at 0. Went out right after we finalized everything, and flew it. Still carries a slight left trim in it, but TONS better!!!!!

Elevator trim, too, can cause us to carry trim in the ailerons, as well. It will be the next thing we do this winter, once he upgrades from the kiddie radio to a big boy radio.

CF~
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Old 09-24-2010, 08:33 PM
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Default RE: cg and balancing!!!!


ORIGINAL: IFLY3W

Just by looking from the ass of the airplane, you can't tell 1 degree difference, and I've got pretty good eyes.
It actually doesn't take real good eyes, but with some experience and knowing how to look and where to look from and how to shift the plane makes it pretty easy to spot even less than 1.

But good thing about our hobby is there is more than one way to do most tasks. If you can't do it one way, there almost always is at least one other way, and using tools often doesn't take a lot of learning.

BTW, if it still carries slight trim in it, there is something the tools missed.
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Old 09-26-2010, 05:32 PM
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Default RE: cg and balancing!!!!

well knowing what i know now,every plane that I build will be checked. the mx-2 only has maybe 1 or 2 clicks of trim in it.And as the fry guy said, a better radio will make a big difference. I will go with a dx8i or the JR 9303. any thing will be better than dx6.

R Shaw.
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Old 09-26-2010, 05:56 PM
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Default RE: cg and balancing!!!!

A fancier radio can't cure mechanical setup issues, only mask them.
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Old 09-26-2010, 06:24 PM
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Default RE: cg and balancing!!!!

Its not the issues with the airplane but the speed of the receivers. dx6 it dog slow compared to a dx7. dx8 and jr 9303"s are much faster radio's. In my book , a plane with mechanical issues should never see the flying field!!!
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Old 10-08-2010, 11:59 AM
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Default RE: cg and balancing!!!!

Or a 10X with a DSM2 module...........
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Old 10-08-2010, 01:21 PM
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Default RE: cg and balancing!!!!

To tell if your plane is laterally balanced, fly an inside loop than an outside loop; if you're out of balance, one wing will be substantially lower. 2oz is a lot of weight to add to a wing tip.

To check the angles of your wings and stab, fly the plane away from you and pull an inside loop. Does the plane corkscrew? If so, you've got an alignment issue.

It could be something like your stabs are misadjusted and you're correcting for it with aileron trim.

Could be a lot of things, but the tail is the first thing I'd check.
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Old 10-08-2010, 09:34 PM
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Default RE: cg and balancing!!!!



It only has 2 1/4 oz weights on the right wing tip now. but since chris and i fixed the incidence pins, it flys much better. now i just need to upgrade the radio in it. dx8 or a 10x. not sure yet.

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Old 10-12-2010, 04:50 PM
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Default RE: cg and balancing!!!!

The plane has a split elevator right? how is each elevator feather actuated? separate servo or push rod splitter in the fuse?

Check both to ensure that;

servo's are working in sync and that one is not slower than the other

if a splitter typre, check the push rods for binding or flex.

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Old 10-12-2010, 06:51 PM
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Default RE: cg and balancing!!!!



Trust me. That isnt an issue. Each half has its own servo. i use a digital Hitec 5000 ser. servo. 135 in-oz each. They track prefect. Since the incidence pins were readjusted , all the problems are gone.

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