|
Page
1 • 2 •
3 •
4
Locate each aileron-servo's position. Mounting the
servo in the middle of the aileron's span is best but is unnecessary on
trainer and sport ARF models. It works well to locate the servo on the
inside of the wing bay that allows the servo's wire to just reach wing
center.
Using a 6-inch servo extension makes it easy to connect the
ailerons at the flying field without making the servo wire so long that
it causes radio problems. You should tie the connectors together to
prevent separation during installation and flight.
Position the servo
next to the inside wing rib. Place the forward servo mounting lugs just
behind the main spar. Mark the back of the rear mounting lugs. Use a
sharp hobby knife to carefully cut away the covering to a point roughly
1/2 inch behind the rear mounting lugs. Use a piece of low-tack tape to
prevent the covering from tearing.
Cut a piece of 3/16 scrap balsa
approximately an inch higher than the wing is thick and roughly the
length of the opening. Position it against the wing rib. Draw a line
matching the wing rib's curvature, and put this piece aside for now.
Use
five-minute epoxy to make the forward servo-mounting rail. This is
fabricated from two pieces of 3-inch-long 1/2 x 1/4 spruce and 1/4
triangle-stock spruce that is the same length. After the epoxy sets, cut
this assembly into two parts. Epoxy each to the rear of the front wing
spar and against the wing rib. Make sure the assembly is mounted under
the capstrip, if present, and against the wing rib.
Make the rear
servo-mounting rail from a piece of 1/2 x 1/4 spruce rail. Reinforce the
mounting area using 1/4 spruce triangle stock. The rear rail spans the
entire distance between the wing ribs, so be careful when determining
this measurement. Position the servo on the front rail, which is already
installed, and use it to position the rear mounting rail. Glue the rear
rail in position with five-minute epoxy.
I have never trusted cyanoacrylate glue for this job because the servo mounts will be
stressed for the next thousand flights. It might work great, but I have
never used it for this type of high-stress work. The choice of adhesive
is up to the builder.
Feed fishing line or string through the wing
center-section and into the newly created servo bay. Tie it around scrap
wood to prevent it from being pulled back inside the wing. Do the same
at wing center. Once the wing halves are joined, the string will exit
the wing bottom at the original center servo location. It is used to
pull the servo wire through the wing and out the center during final
assembly.
Shape the balsa piece you made as necessary to form the
outside wall of the new servo bay. If you want, shape a piece of 1/16
balsa to make a servo floor. Position the servo on the mounts. The front
mounting lugs should be even with the top of the spar. If they are not,
use scrap 1/16 plywood—not balsa—to raise the lugs to be level with the
wing surface. Position the servo and drill the mounting holes. Remove
the servo.
Use scrap balsa to raise the area of the mounting rails not
covered by the servo to the same height as the wing's surface. Carefully
remove the protective tape.
Use a plastic-covering trim iron to reposition the covering, and cut the
servo opening. Or, if you prefer, reposition only the part of the old
covering that goes over the rear mounting rail, and then use new
material to cover the entire opening, cutting out the new servo bay. The
choice is yours; but if you use all the old covering, place some
1/4-inch trim covering over the cut lines around the entire opening.
Click on photo to view large image with caption
Page
1 • 2 •
3 •
4 |
