.
14. Locate the 1/16"x7/8"x2-1/2" plywood
wing hold-down plate, then round off the
top edges and the corners with a
sanding block. Glue the wing hold-down
plate to the top of the wing so that it's
centered left to right and overhangs the
trailing edge 3/16".
Carving Vortex Wingtips
The down-turned vortex wingtips used on the Standard version of the Wonder
were chosen more for their looks than any kind of aerodynamic reason.
Theoretically this type of wingtip is very efficient, but on a model of this size it
really makes little difference.
They are easier to carve and sand than
they appear, so give 'em a try!
1. Cut out the top view of the wing tips
(see step 12 above). Draw a line on the
inside surface of each tip, 11/16" from
the bottom.
2. Glue the wingtip to the end rib so
that it's flush with the bottom of the
airfoil and the drawn line passes
through the exact center of the trailing
edge. When dry, us the WT wingtip
plate (cut from plans) to mark the
shape of the trailing edge on each
wingtip.
3. Carve and sand the wingtip blocks to
match the contour of the entire upper
surface and back to the spar on the
lower surface.
4. Rough carve the concave portion of
the tips using an X-Acto #162 router
blade.
5. Finish sand the concave portion with
a large dowel wrapped with 80-grit
sandpaper.
6. The rest of the block can now be
carved and sanded pretty much like a
normal, rounded wingtip. Be sure to
strengthen the trailing edge area of
each wingtip by soaking then with thin
CA. Smooth things up with a hand-held
piece of 150-grit sandpaper.
WONDER WHY...
...there's no dihedral brace or
sheer webs in the wing?
Answer:
All of the spars and sheeting in the
Wonder wing run the full span of the
wing, from tip to tip. Since there is
no center wing joint, there's no need
for a dihedral brace or reinforcing
fiberglass tape. The center sheeting
is more than adequate to absorb the
aerodynamic loads at the center of
the wing.
None of the Wonder prototypes ever
used, or needed, shear webbing.
The low-aspect-ratio, 15%-thick
wing simply doesn't need the extra
strength or weight of shear webs,
and you don't need the extra work of
installing them!
15.
a. Draw a line on the trailing edge at
the exact center of the wing, then
two more lines spaced 1/2" on
either side of the center. The
second two lines indicate where
to position the inner end of the
torque rod brass bearings, which
should now be glued in place.
Make certain the torque rod
assemblies are centered vertically
on the wing trailing edge and be
careful not to get any glue in the
bearings.
b. When dry, fill the small gaps
above and below the torque rods
with more glue or balsa filler and
sand it smooth.
c. Cut clearance notches in the wing
trailing edge for the inner end of
the torque rods.