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NEW
ADDITION : We have now begun using a heat gun or blow dryer to form the
airfoil section. You can quickly and easily form a beautiful
airfoil by bending the top of the wing over an object while applying
heat. If you don't have access to one of these, then use
the method below.
As
I mentioned earlier, treatment of the top of the wing is important to
getting a smooth airfoil. Not that a slightly diamond shaped foil
seems to matter on a good slope day, but it does in light lift.
So, to get the smoothest foil shape, open the wing panels so that you
can lay the top flat. Draw the same line you used to locate the
former on the top panel (3" at the root 1-1/2" at the tip). This
will be a guide to let you know how far to go.
Using a yard
stick along this mark, scribe, or crease the foam using a Bic pen top
or some slightly pointed but round implement. Space the lines
1/4" apart from that line to the crease of the leading edge, so that
the entire length looks corrugated. This will allow the foam to
curve rather than bend at the high point of the former. It does
help to "exercise" this area a bit to loosen it up before joining the
trailing edges.
With everything in place, test fold the
section. You will see that the leading edge tries to lift up as
you fold over the former. You must hold the leading edge down as
much as possible when joining to get a nice flat wing with trailing
edges that meet nicely. If necessary, get two more hands to help
you. If the top and bottom trailing edges don't meet exactly,
don't fret, because minor variations between my dimensions and yours
will cause some variance. You can either sand them smooth or use
a sharp knife to get them to line up. Either way, I bet she still
flies!
I have used 5 minute epoxy, hot glue, contact cement, and
poly glue on this joint and all work great. Again, my vote goes
to the hot glue gun because of its' ease of use and quick set.
Which in this step is a bonus.
NOTE
: The top panels will most likely not meet in the middle, but don't
worry about that. You'll probably end up cutting the top all up
to get your radio gear in anyway.
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