6
Installation of the Control Surfaces
1. Trial fit the vertical fin onto the fuselage. Before the fin is glued in permanently make sure that it is
perfectly straight. To do this, slide in the stab tube and center it by measuring both sides from the
fuselage. Once you have the tube centered, measure from the end of the tube to the tip of the fin on
both sides. This measurement should be exactly the same if the fin is straight. The best and easiest
way to measure is to tie/glue a string to a “T” pin and pin it to the tip of the fin. Then extend the
string to one side of the fuselage to the end of the tube and make a mark, next, without removing the
pin, move the string to the other side of the fuselage to the end of the tube. The mark should be at
the same place for both sides. If the measurement is not the same, carefully sand the fin base on the
fuselage to “straighten” the fin. Once you feel that it is straight, use 30 minute or slower epoxy to
permanently install the fin, while the glue is drying, use tape to secure the fin.
2. Glue in the Hinges for the Ailerons, Elevator, and Rudder. Use epoxy or hinge glue works very well
for this application. Grease (Vaseline) or oil the hinge line to prevent any adhesive from getting into
the hinge line, which would bind the hinges.
3. The hard points for the control horns are plywood plates that are glued to the foam core at the top
and bottom of the control surface, flush with the balsa skin. Drill holes at the top and bottom hard
points for the aileron and elevator, and at the left and right hard points for the rudder. The trick to
drilling the holes for the control horns is to drill from both the top and bottom of the hard points,
making sure that the drill marks at the top are exactly at the same location as the marks for the
bottom. Since you will be drilling only thru 3/32 skin and 1/8 or 3/16 ply, it not very deep, so there's
no need to be exactly perpendicular to the control surface centerline. Once you have drilled from
both sides, then go back and drill again from one side only, and let the drill go thru the other side,
but carefully, making sure you don't drill a new hole. Now the holes are perpendicular to the control
surface centerline. When installing the control horn bolt, as you get close to the other side, keep an
eye on the bolt from the hole in the other side to be sure that it is starting well on the hole, otherwise
you might push the plate and cause it to debond from the foam. When installing the plastic nut for
the control horn, don’t tighten too much, or you will crush the foam beneath the hard point. Put a
dab of loctite or 5-min epoxy on the control horn bolt and nut to prevent them from rotating and
becoming loose from engine vibration.
4. The locations for the hard points are as follows:
Ailerons: The centers of the hard points are located approximately 11”, 26 ½”, and 46 1/8” from the
tip of the aileron. Measure these distances along the bevel line from the tip of the aileron. The sizes
of the hard points are 1 ½ wide by 3 inches long x 3/16 inch thick and are located at the top and
bottom of the aileron. After locating the hard points, make a mark ½ inch behind the bevel line. It is
recommended that the location of the hole be offset slightly towards the servo (not on the center of
the hard point, or directly in line with the point where the pushrod is attached to the servo arm) so
that when the servo is at full deflection, the pushrod is perpendicular to the hinge line axis. This will
give maximum torque to your control surface at the maximum servo deflection. Repeat the
procedure for the hard points at the bottom.
Elevator: The centers of the hard points are located 8 1/8”, and 17 3/8” from the tip of the elevator.
Measure these distances along the bevel line from the tip of the elevator. The size of the hard points
