CHECK FOR WARP - FIX IF NECESSARY.
GOOD WING • BOTH TIPS ARE IDENTICAL A 7 TRAILING EDGE
WITH SAME AMOUNT OF WASH-OUT AT TIPS
TRAILING EDGE UP
TOO HIGH AT TIP
FIGURE 33 - IDENTIFYING WARP
VIEW FROM TRAILING EDGE
Now is the time to see if you have built a straight wing. Set the wing up on an arm chair, with the trailing edge facing you.
Stand back about 10 feet and do some "kneebends," observing the trailing edges. Your wing, when properly built, will have
1/4" to 5/8" of "washout" at the trailing edges (the trailing edges will be "up" slightly at the tips relative to the root).
It is more important that both wings be the same than it is for each to have some prescribed amount of washout. If both
halves are the same, the wing will fly straight.
A warped wing can have several causes: improper alignment of the trailing edges; incorrect spar placement; or not using
a flat surface when gluing. If you lift the wing off of your table to glue the trailing edges and "compress" the trailing edges
with your hand to "crimp" it together, you will put opposite warp in both trailing edges. If you are right handed, you will always
build a wing that will roll to the left this way, with opposite warp in each wing half! The secret to a warp free wing is (a) lining
up the trailing edges to each other exactly and (b) using straight-down hand pressure with the heel of your hand on the
table top to bond them. The neat thing is, once your AirCore wing is built straight, it will not change its shape like traditional
(balsa) construction planes will over time.
If you discover warp, now is the time to fix it. In a few minutes, you can correct the problem and have a wing you will be
proud of. It requires you to delaminate the wing tip and trailing edge of the wing and reglue it.
There is an "old wives' tale" that you cannot disassemble something stuck together with contact cement. Not true! If you
ever need to "delaminate" a part glued with contact cement, simply use a blunt (not sharp) table knife and some lacquer
thinner. (Don't get lacquer thinner on your decorated parts). Use a Q-tip if necessary to get the lacquer thinner into the joint,
let it work a minute, then use the table knife to separate the two pieces and pull them apart. With patience, you can
delaminate the major joints in the entire airplane in about an hour! With this in mind,delaminate the wing tip flap first, then
the trailing edge you wish to correct. Reglue them, changing the relative locations of the trailing edges as you glue in an
effort to cure the warp. Glue the trailing edge first, then the wing tip. Just a 1/16" difference in the way you line up the trailing
edges can make a 1/4" difference in the amount of wash-out you have in the trailing edge of the wing. Keep the wing on a
flat surface while gluing. Think it through before you begin, and you will be pleased with the results.
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