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Read through the following instructions entirely prior to starting so that you have an overview of
what is involved. Please don’t be tempted to deviate from these instructions unless you are an
experienced builder and are certain that your changes won’t negatively affect the structural integrity
or flying performance of the Booby. These instructions are based in metric units but I have also
tried to include the equivalent imperial measurement as much as possible. For your reference, 1
inch (”) equals 25.4 millimeters (mm). These instructions are also available in colour as a MS Word
document online at
www.wowings.com/instructions/wowings_booby.doc
SPAR INSTALLATION
Polyurethane (PU) glue is probably the best option for gluing in the wing spar. It foams up and
expands during the curing process and penetrates into the surrounding EPP foam creating a strong
tight bond without adding a lot of weight. However, if not used properly it can create a mess and
possibly even ruin the wing. For this reason, these instructions will focus on using more fool-proof
glues instead. If you decide to try using a PU glue for the first time, it’s best to experiment a little
on some scrap EPP before applying it to your wing. Ensure there’s a layer of waxed paper between
then wing and the bottom wing bed because the PU glue penetrates through the EPP easily. Be
sparing with the amount of PU glue used and wipe the spar with a damp cloth prior to gluing in
place to help the glue activate. Ensure that the wing is adequately weighted down in its beds while
the glue is curing.
If you want your Booby to be compliant with EPP slope combat competition rules, you may need to
trim the spar by about 25mm (1”) at the wingtips before gluing in place so that it is set back far
enough from the wing’s leading edge. Please consult your local rules for specific requirements.
1.
Locate the two lengths of black fiberglass spar and the internal spar joiner. Use 5 minute
epoxy glue to attach the two spar halves together over the internal joiner, creating a full
length straight spar.
2.
Remove the foam wing cores from their beds. Gently bend open the spar slot and carefully
remove the foam “noodle” from the spar channel. Trial fit the spar to ensure that no bits of
foam have been left in the spar channel. It should fit easily without the spar slot opening
being forced apart. Also check for acceptable alignment of the two outer wing sections with
the central wing panel. Remove the spar and put it aside to be used shortly.
3.
Glue the two outer wing sections to either side of the central wing panel using hot-melt glue
or spray adhesive (epoxy is also OK but a little brittle). Align with the panels’ spar slot and
ensure the top and bottom surface of each panel is also flush.
4.
Lightly sand the fiberglass spar to roughen its surface and remove any remaining mold
release agent and wipe off the dust.
5.
Gently bend open the spar slot and run a bead of goop/goo style glue (30 minute epoxy is
also OK but not as good) inside the spar channel. Starting at one wing tip, bend open the
spar slot and push the spar down into the spar channel. Once the spar has been inserted, use
a piece of dowel, or back of a pen or pencil, to push the spar firmly all the way down into
the channel so that the glue is forced up and around the spar, coating it entirely. This process
can also be helped by repeatedly bending the wing chord-wise, temporarily closing and
opening the spar slot to help work the glue around the spar and centre the spar in the spar
channel. Wipe off any excess glue.
6.
Place the entire wing back into its foam beds and rest it on a completely flat surface (eg.
table or floor). Weight it down so that the wing is kept flat and completely snug with the
bottom curve of its foam beds. To avoid deforming the foam make sure the weights aren’t
