SIG RASCAL FORTY, Assembly Manual

servo opening.

The rudder servo fits into the left rear servo

opening and the throttle servo fits into the forward opening.
Position the throttle servo with its output arm on the correct side
for connecting to the throttle pushrod. Use the mounting screws
provided with your radio system to mount the servos in place to the
servo tray.

The on/off switch can be mounted wherever it is most convenient
- typically this is on the left side of the fuselage. If you want the
switch in this location, you will need to cut a small rectangular slot
for the switch in the fuselage side. Then, just mount the switch with
the hardware supplied in your radio system. We prefer to mount
our switches internally and in this design this is fairly easy to do.
We placed the switch on the floor of the fuselage, just behind the
main landing gear mounting block. We drilled the switch lever to
accept a piece of .046 music wire. The wire simply extends out
through the fuselage side with a simple “L” bend. Whatever switch
mounting method you use, always make sure the switch is
securely in place with no pressure on the wiring.

With the servos and switch in place, the receiver can now be
placed into the fuselage.

Connect the servo leads to the

appropriate channel in the receiver.

Also plug the “Y-harness

connector in place into the aileron channel and the switch
connector into the receivers battery receptacle. Wrap the receiver
in protective foam, held in place with rubber bands, tape, etc.
Install the protected receiver into the compartment directly
beneath the servo tray. The “Y-harness” leads should both be left
sticking out of this opening and accessible. Likewise, the receiver
antenna should also be exiting this opening in the fuselage former.
Gently press the receiver in place beneath the servos.

We have found that with this design, the easiest way to route the
antenna out of the fuselage is to make a small hole, (about 1/16”
or so), in the bottom fuselage sheeting, just ahead of the middle
cabin former. To avoid pulling on the antenna at the receiver, fit the
antenna wire with the radio manufacturer’s supplied strain relief
fitting. Route the antenna through the hole and back toward the 

tailwheel bracket. We made a simple wire hook from a straight pin
and attached it to the forward screw holding the bracket in place.
We then used a rubber band to anchor the antenna along the
bottom length of the fuselage.

For now, leave the battery pack loose. When you check for the
correct Center of Gravity in the next few steps, the battery pack will
be positioned as needed. At that time it can be wrapped in foam
and placed in the fuselage.

Installation of the pushrods in the following steps requires the use
of your radio system. Therefore you should now prepare the radio
system for this purpose. First, make sure both the airborne and
transmitter batteries are charged. Next, turn the system on and
check the throttle, elevator, and rudder servos for the correct
direction of travel.

Using the transmitter, reverse any servo

traveling in the wrong direction. Make sure that the trim levers for
these servos are all in neutral.

Last, prepare and mount 

the servo output arms onto each servo - do not install the locking
screw at this time. As shown, we prefer using 4-arm output arms,
using the longest arm for the linkage. We also typically cut-off the
remaining, unused arms to avoid clutter. The rudder and elevator
pushrod connections will be made on the outside of these two
servos. Therefore, the servo output arms should be mounted on
the servos with the link holes at 90

O

to the servo - this is going to

be the “neutral” position for the rudder and elevators. The throttle
servo arm is typically mounted at approximately 45

O

, allowing

uniform travel in either direction (final adjustments to the throttle
linkage will be made during set-up).

PUSHROD INSTALLATION:

The control pushrod system used in this design is very straight-
forward. The outer nylon control tube housings have already been
installed in your model. What remains is to make the inner nylon
pushrod connections from the servos to the rudder, elevators, and
throttle. From the kit contents locate the following parts:

2 each

M4 x 40mm (1-9/16”) Phillips/Washer Head Axle Bolts

2 each

Inner Nylon Control Tube - 
Rudder and Elevator Pushrods

1 each

Inner Nylon Control Tube - Throttle Pushrod

6 each

Threaded Metal Control Links

6 each

M2 x 7/8” Threaded Control Link Studs

2 each

Nylon Control Horns

4 each

M2 x 3/4” Phillips Head Bolts - 
Control Horn Attachment

❑

1) Begin with the rudder pushrod.

Install one of the 7/8”

threaded studs into one end of a 25-3/4” inner nylon control tube.
Thread the stud into the tube about 1/4”. (A neat way to do this is
to use an electric hand drill. Lightly chuck the stud into the drill and

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