Extreme Flight 125" EXTRA 300 Assembly Manual page 7

9. It is highly recommended that you use a servo programmer, Matchbox or power
distribution unit to make sure all 3 servos work in unison. We use the Hitec 7955s and
7950s in our aircraft in conjunction with the Hitec programmer and have been able to get
the servos matched perfectly with very little current draw.
Elevator/stab assembly
10. Just as you did with the wings, take a few moments to go over all the seams and stripes
with a hot iron to ensure all edges are sealed.
11. Use a flat head screw driver to back out the threaded portion of the hinge pin rod at
the root of the elevator. Place a couple drops of blue Loctite on the threads and re-tighten
the hinge pin rod. Repeat for the other stab/elevator half.
12. There are provisions to use 2 elevator servos per half included with the Extra. We
have found one ultra torque servo to be sufficient (Hitec 7955 or 7950, JR 8711 HV, Futaba
9156 or 9157). If using a single servo use the servo mount furthest outboard on the stab
and the corresponding elevator horn slot.
13. Using the same technique as with the aileron mount the elevator control horn as
shown. All of the elevator horns are identical.
14. Install your servo using the manufacturer supplied mounting hardware with the
output shaft oriented toward the trailing edge of the stab. Thread a ball link onto each end
of the threaded titanium pushrod and install using the supplied hardware as shown in the
picture. We use a 1.5 inch aluminum servo arm for elevator actuation. If setting up the
Extra for precision aerobatics only we suggest using a 1 inch arm for better resolution.