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alignment of wing, fuselage and tail surfaces?

Old 11-06-2008, 10:46 AM
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Popriv
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Default alignment of wing, fuselage and tail surfaces?

Skyraider MKI high wing trainer. I've just finished rebuilding the fuse after I snapped it of right behind the wing.

The fuse appears to be as straight as I can measure it? when I mount the wing (I had to rebuild the wing hold down blocks), I measure from the tip of the wings back to the center of the tail of the fuse. (the tail surfaces are removed) THE MEASUREMENT TO THE RIGHT WING TIP IS 1/8" TO 3/16" LONGER THAN THE SAME MEASUREMENT TO THE LEFT WING TIP.

For the elevator the instructions show to measure from the nose of the fuse back to the outer tips of the elevator.
So both of these measurements would square the wing and elevator to the fuselage.
If the wing is off slightly as I indicated, would I be better to align the elevator square with the fuselage or should I make it parallel to the wing?

Am I worrying to much? is this amount not going to make a difference on a trainer?

Do you check these measurements? If so, what kind of results do you get with ARFs?

Thanks

Steve
Old 11-06-2008, 11:00 AM
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Default RE: alignment of wing, fuselage and tail surfaces?

I would not worry about it. To be out only 1/8" may well be closer than it was when it was made. Just square everything to the fuselage and it should be fine. I had a very expensive aerobatic bi-plane ARF recently that had a similar problem. Except that planes wing was 1 5/16" out. Now that's bad.
Old 11-06-2008, 11:00 AM
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Default RE: alignment of wing, fuselage and tail surfaces?

That will not matter much. I have had them hay worse then that after a big crunch and they fly just fine.

Fly, crash, rebuild, repeat.


Dru.
Old 11-06-2008, 11:13 AM
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jib
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Default RE: alignment of wing, fuselage and tail surfaces?

My Ultrastick was out over 5/8 side to side. Hanger 9 was willing to replace the wing, but not until I shipped it back. I didn't want to wait, so (under the advice I received from the folks on this forum) plugged the old holes with dowels and redrilled new holes in the wing.

jack
Old 11-06-2008, 11:19 AM
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Default RE: alignment of wing, fuselage and tail surfaces?

Yes, you'll be fine. I had a plane that was a bit worse than that. Only when I started to practice precision aerobatics (pattern) it became a problem.
Old 11-06-2008, 11:27 AM
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Popriv
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Default RE: alignment of wing, fuselage and tail surfaces?

When flying this plane I had noticed that in a loop it tracked off to one side. (could have been my lack of skill!) I hadnt checked these measurements before the crash but I could see that if these surfaces were off, especially the elevator, a loop would be more of a cork screw?

I didnt think 3/16" would be to bad but when they say make it as straight as you can, well, given enough time and effort, it could be made perfect.

So, wing is done and I'll mount the tail surfaces tonight. They bolt on but I'm going to enlarge the holes slightly. cut back some covering and use epoxy along with the screws. I can then align the tail to the fuse, tighten the screws and let the epoxy do its thing.

thanks

Steve
Old 11-06-2008, 11:31 AM
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Default RE: alignment of wing, fuselage and tail surfaces?

Comparing two different measurments one referencing the nose and the other the tail will likely be off no mater what even sometimes with a new airplane much less one that has has had major fuselage repairs where an intangeble bow has been built in.

I do a lot of rebuilding primarily from dumpsters and some of my own simply because its fun and everyone a different challange. I have found with one exception The very best measurement is done with my eyeballs not a ruler. For planform alignment stand the airplane on its nose with the wing installed with the wheels aginst a garage door or wall and step back twenty feet and look. Any misalignment will be obvious and for side to side alignment just set the airplane on a table the same height as your eyeballs and step back agine 20 feet in front and look. Any needed adjustment will be obvious. For what its worth on this adjustment its best to keep the relationship (of the wing and stabilizer) the same even if it is a little out to the fuselage. Then its easy to set the vertical ninety degrees to the horizontal.

What often happens with a box section fuselage is the fuse bottom does not end up quite square in rebuilts and it won't set quite square on the table without the gear when aligning the wing and horizontal.

John
Old 11-06-2008, 11:33 AM
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Default RE: alignment of wing, fuselage and tail surfaces?

I had a plane that was heavily repaired and it was more than 1/2" off and the vertical stab leaned about 10 deg to one side and it was one of the best flying planes I have ever owned.
Don't worry too much about it, see how it flys.
Old 11-06-2008, 12:59 PM
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Default RE: alignment of wing, fuselage and tail surfaces?

Just remember epoxing parts on seems like a great idea till the next accident comes along and all of a sudden you wish there was an easy way to remove and replace or re-use that part
Old 11-06-2008, 01:29 PM
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Default RE: alignment of wing, fuselage and tail surfaces?


ORIGINAL: Popriv

When flying this plane I had noticed that in a loop it tracked off to one side. (could have been my lack of skill!) I hadnt checked these measurements before the crash but I could see that if these surfaces were off, especially the elevator, a loop would be more of a cork screw?

I didnt think 3/16" would be to bad but when they say make it as straight as you can, well, given enough time and effort, it could be made perfect.

So, wing is done and I'll mount the tail surfaces tonight. They bolt on but I'm going to enlarge the holes slightly. cut back some covering and use epoxy along with the screws. I can then align the tail to the fuse, tighten the screws and let the epoxy do its thing.

thanks

Steve
There are a lot of things that can cause you to track out of a loop, but an out-of-square plane is one of them. It's a repaired trainer, so don't worry too much about it; fly it until you're totally bored with it, or totally annoyed that it doesn't track straight and you know you're ready for the next step.
Old 11-06-2008, 02:24 PM
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Popriv
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Default RE: alignment of wing, fuselage and tail surfaces?


ORIGINAL: Deathbunny_SG

Just remember epoxing parts on seems like a great idea till the next accident comes along and all of a sudden you wish there was an easy way to remove and replace or re-use that part

Understood! It was nice to be able to just unbolt the tail...

I would only epoxy if I have to twist it a little for alignment.

From what everyones is saying it looks like I can finish this up tonight. sounds like its close enough. hopefully fly it Saturday.

I may be a little tail heavy? as the repairs are slightly back of the CoG, Fuse is doubled up at the trailing edge of the wing. Thats where it broke.
I'll adjust the CoG as needed.

steve


Old 03-19-2020, 10:48 AM
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Maxi100
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Default Wing out of line

Hi my issues or confusions are as follows: I have a Chris's foss 5E glider , with the aircraft assembled, looking down the aircraft from nose down, the wing incidents to the elevators are not square
...off by 3mm avg ...so I guess this was a manufacturing default,so I balanced this out with tape on one side of the wing . So now the elevator and wing are horizontal to each other ...My thinking is that the aircraft would not drift left/ right ?...In doing this I found that the elevator setting is now 70% down ..but have good down nose
CG ....do I still require that offset incident that I have mentioned in the above ???
TIA
Old 03-22-2020, 12:20 PM
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jester_s1
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Default

Welcome to the forum.
A small point of etiquette: It's better to make new threads than to revive 12 year old ones. No biggie; it just makes it easier tor people to follow what's going on.

For your questions:
-Let's get the vocabulary words right. Incidence is the up/down angles of the wing and horizontal stabilizer as view from the side. What I think you were describing was getting the wing and stab level to each other. Yes, that can cause some sideways drifting.
-"down nose CG" may or may not be set properly. The right way is to mark the correct CG location on the wing based on calculations (Google rc plane CG calculator) and then balance the plane to be LEVEL at that spot. More beginners show up with terrible flying planes due to a sloppy CG setup than any other reason.
-What is the actual angle of your elevator deflection? 70% down doesn't tell us anything, because your radio may have been significantly up.

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