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Old Apr 22, 2012, 02:33 PM
Balsa builder and balsa basher
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Leading edge HELP! for 1.6m Trainer

Ok i need some help, i'm making a scratch built Rc Trainer as my first aircraft. I've completed the wings (both of them) But i noticed one of the leading edges is a little higher than the other . I was wondering if it would make too much of a difference to the way it flys. Here's a photo of the problem.

It's probably very hard to see but the one on the left is 1mm higher than the other will it make a difference
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Old Apr 22, 2012, 05:12 PM
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Joined Sep 2007
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Doubtful that this will have much of an impact on flight characteristics for this type of plane. I have flown many RC high wing flat bottom trainers, both gas and electric. I have flown high flat bottom wing trainers with wings I have repaired that had very little original leading edge material and questionable leading edges. Little to no difference.
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Old Apr 22, 2012, 05:19 PM
OSUFPV - KF7VFT
Corvallis, OR
Joined Apr 2010
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Quote:
Originally Posted by RC Trainer plane View Post
Ok i need some help, i'm making a scratch built Rc Trainer as my first aircraft.
First aircraft? Scratch building help? This is the FPV forum....you're in the wrong place.

-Blues
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Old Apr 22, 2012, 05:45 PM
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Birmingham, Alabama
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on a 1.6m wing, don't worry about it.
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Old Apr 23, 2012, 10:10 AM
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dedStik's Avatar
United States, VA, Virginia Beach
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I'd say if you are a perfectionist fix it, otherwise who has to know?
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Old Apr 23, 2012, 10:25 AM
Balsa builder and balsa basher
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so you don't think one wing will generate a little more lift than the other and at full throught it'll roll ? Thanks for the help
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Old Apr 23, 2012, 10:53 AM
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dedStik's Avatar
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Not with a flat bottom wing no, but if it worries you, some coarse grit sand paper will take out the 1mm in a few swipes.
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Old Apr 23, 2012, 11:29 AM
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The 'Wack, BC, Canada
Joined Oct 2002
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It looks to me more like one joint is simply futher back than the other. Depending on how the top sheet is glued to the leading edges this suggests to me more a case of you sanded down one leading edge more than the other. Alternately you may have slipped up and used a wider piece of wood on one side than the other.

Your pictures are a little too fuzzy and at the wrong angles to tell much more than this. Also without seeing the internal structures and how the rest of the center section joint is done I also can't tell more.

If the wing is flat bottomed and both the flat bottoms are lined up and if the upper side curves are close in shape then you're good to carry on. Like I say, it's impossible from here to see why the glue line of one is higher and further back than the other. But it's the shape of the wings that count. If the bottoms are both lined up and the upper side curves are lined up then don't worry about the joint being staggered back a little on one side.
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Old Apr 23, 2012, 01:58 PM
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United States, MD, Elkton
Joined Oct 2011
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If you have ailerons,it'll be easy to trim out....if it's rudder only,it will be a little more difficult to trim.
Here's a solution if you're too worried....when you cover the wings,make sure the bottom of the wing lies flat on a surface you know is flat,all around.
Measure up to the opposite wing tip,and be sure it is exactly the same distance to the bottom of the trailing edge,as the distance to the leading edge bottom.
You'll have to do this on the flattest part of the rib.at the tip.
If it's off,twist it a little more than that amount the other way,then heat it with your sealing iron...With practice,you'll end up with less 'twist' than you have now.
But in our opinion, forget that minor amount...And no,it won't roll over on you at full throttle ! Nice work-by the way.
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Old Apr 24, 2012, 12:01 AM
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Perth, Western Australia
Joined Sep 2004
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The most important thing to building a straight flying wing is getting the twist (or tack of twist) identical on both sides. It has far more effect that slight variations in airfoil shape. That's what epoxyearl is talking about.
That said, if its a little bit out (my wings are never perfect) a bit of aileron trim will have it flying OK.
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Old Apr 24, 2012, 01:27 AM
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Fixing a warped wing with aileron trim is a band-aid fix, and a poor one at best.

you'll find that as speed increases and decreases you'll be chasing the trim the whole time.

Like the guys say, make sure your join is as straight as you can make it. Pay special attention to the trailing edge, to ensure that they line up, and have similar flatness or washout at the tips. Take your time.

A square aeroplane that flies true is a joy. A wonky out-of-square plane is not.
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