If you’ve
ever had a control surface come loose in flight and
lost an aircraft as a result, you’ve probably given
serious consideration to pinning hinges for added
security.
Sometimes you get away
with a detached control surface, but when you have
no elevator, or an aileron is partially pulled out
at an angle, you can lose an aircraft quickly.
The most common hinge
types used today are the nylon hinge and the
flexible CA hinge that Sig markets as the "Easy
Hinge." You’ll also find metal hinges used in some
of the Almost-Ready-to-Fly (ARF) airplanes. Nylon
and metal hinges are normally glued into position
using epoxy glue. To avoid epoxy from getting on the
hinge joint, modelers sometimes coat it with
Vaseline or oil.
The installation of nylon
or metal hinges is a more time-consuming and tedious
process than the installation of the Easy Hinge. The
Easy Hinge is slipped into slots in the control
surface and in the wing or tail structure after
which CA is dripped on to the exposed portion of the
hinge and wicked into both ends of the hinge by
capillary action.
In order to provide
assurance that control surfaces won’t detach in
flight, many modelers pin their hinges. There are
two basic methods.
The first is the use of
the classic, round toothpick. Using a 3/32
–size drill, drill through the hinge on both the
control surface side and wing or tail structure
side. Install the toothpicks using epoxy or white
(aliphatic) glue. When the glue sets, clip the
toothpicks as close to the surface as possible and
then sand the ends flush.
Because sanding is
impractical when covering is already on the
aircraft, you can carefully grind the toothpick ends
flush using a Dremel tool. Cover or paint as
appropriate. Note: Some articles recommend the use
of CA glue. I don’t because CA can set so quickly
the toothpick may not be properly installed.
Another method for pinning
hinges involves using two types of steel pins in
combination. This method won’t work well with metal
hinges because of the difficulty of drilling through
the metal with the larger pin used as a drill bit,
but I have used it with nylon hinges and it is
especially suited for the Easy Hinge. I’ve found
using the steel pin method with Easy Hinges is the
quickest and most secure method.
Here’s how the steel pin
method works. First, you need two types of pins—a
box of "Tailor" pins and some modeler’s T-Pins. You
can get the Tailor pins from any store that carries
sewing items. Modeler T-Pins can be found at your
local hobby shop.
You may encounter some
difficulty drilling through nylon hinges.
Conversely, your T-Pin drill bit will go through the
Easy Hinges like butter. Note: You might use a
1/16-inch drill bit versus the
T-Pin bit. The diameter is slightly bigger than the
T-Pin shaft but it should work and may make the job
easier when dealing with a regular nylon hinge, and
especially a metal hinge.
Now that you’ve drilled
your pin holes, it’s time to install the Tailor
pins. Since the shaft of a Tailor pin is thinner
than the T-Pin, the Tailor pins fit easily into the
drilled holes. Install them in the holes from the
top down so the pin top will appear on the upper
wing, tail, and control surface.
Leave roughly 3/8-inch
of the pins exposed. Mix up a batch of 30-minute
epoxy. Dab some epoxy on the exposed portion of each
pin and slide all the pin tops flush. Let the epoxy
set. Then, clip off protruding pins on the underside
of the wing, tail structure, and control surfaces
(or one side of the vertical stabilizer).
This method is fast! When you get done, the tops
of the Tailor pins will show but they are quite
small and far neater in appearance than the
toothpick method, particularly when used to pin the
hinges of an ARF.