Sukhoi SU 31—2.75m/2.6m Page|18
Parts Required:
•
Rudder tray components
•
Rudder parts bag
•
Phenolic servo arms
•
Rudder Servo(s)
JR NX8921 or DS6311HV
Futaba S9157 or BLS172HV
•
Alloy servo discs
•
Alloy Servo Arms (optional)
•
SWB 4.5 Full arm, plus 3 Full arm (front servo)
•
SWB or Secraft turnbuckles 50mm (2 )
Tools Required:
•
Steel rule(s)
•
Marking pen
•
Philips head screw driver
The rudder tray provided is suitable for 2 servos. You may elect to use 1 x 30kg plus servo. The servo tray is designed
to fit into the fuselage former at the beginning of the turtle deck. Before you proceed, you should assemble the model,
and do a preliminary C of G check to make sure that you will meet the C of G requirements. If the model is tail heavy
now is the opportunity to move the rudder tray further forward in the fuselage. If you do need to move the rudder tray
forward, you will need to make 2 new ply formers to attach to the existing rudder tray.
The supplied phenolic arms are required to be mounted onto alloy servo discs.
DO NOT USE THE STD NYLON
SERVO DISCS!
The standard discs provided with the servos may strip under heavy loads resulting in control surface
flutter. Screws are provided in the hardware pack to attach the phenolic arms to the alloy discs.
As an option you can elect to use alloy arms. The alloy arms need to be 4.5 for the rear servo and 3 for the front
servo. (You may also wish to use turnbuckles and ball links to connect the 2 servos). An offset arm is preferable, as
the pull/pull cables are to be installed crossed.
Assemble the rudder tray from the wooden components. Don forget to fit the mounting doublers where the servo sit.
You may wish to drill a hole for the servo leads to pass through in the rear former. If you have elected to mount the
servos in the standard (rear) location you can fit the former to the tray at this time. Lightly sand the area in the fuselage
where the tray will be attached. Before you epoxy the tray in place make sure that it is centred in the fuselage. You can
use CA and kicker in a couple of spots to hold in position while the epoxy cures.
Rudder Servo(s)
