wire for majority of Giant Scale airplanes.
consist of a diagram and may be lacking for a first timer.
Heavy Duty Pull-Pull System and Full Dual Servo Arms
has introduced a line of accessories for Giant Scale planes
including a complete pull-pull package. The only item missing
will be a dual servo arm (which is also available) matched
to your particular servo. Both the pull-pull system and servo
arm are made with high quality materials and can be used on
most any aircraft.
Heavy Duty Pull-Pull System and Full Dual Servo Arms
Included in Part# 883 was the following:
4? 8-32 all threaded rod
Locking cones and (2) nuts
Nylon control horns and matching nylon clevis
(4) 2-56 threaded Rigging Couplers
(4) Locking keepers with cotter pins and 4 crimps.
(5) 4? Heat Shrinking tubing
(1) Roll of15? nylon covered steel wire
lot of parts come out of that little package! To install a
Pull-Pull system on my SlipStream RV-8 everything was included
with the exception of the dual servo arm and I?m sure
they would have included that if Du-Bro knew what brand servo
was being used. Because I have a JR servo mounted for the
rudder, Du-Bro was gracious enough to also supply their newest
?Full Dual Servo Arm? (P/N #3345) for JR servos.
With all the parts accounted for, assembly was started.
those who have never installed a Pull-Pull system a quick
overview may be desired. There are three components that make
up a Pull-Pull system: Rudder assembly; metal cables; and
Full Dual Servo Arm. The rudder assembly must have two control
horns (one horn on each side). The cables must then connect
the rudder to the third part, the dual servo arm.
is best to assemble as much as possible off the aircraft as
possible, but eventually your last connections will have to
be done on or in the airplane itself. Many like to start installing
this type of system at the rudder, others start by connecting
the cables to the servo arm. Whichever is easiest for you
? go for it! For our purposes here, the rudder gets the
A 5/32? hole was drilled in the rudder, in line with
the fuselage slots for the cables. One side of the 8-32 rod
was completely fitted and that assembly was inserted into
the rudder followed by the locking washer, tapered cone, locking
nut and control horn. Then the Rigging Coupler was threaded
into the clevis about 5 turns and the clevis attached to the
control horn with locking pins and cotter pins.
this arrangement the rudder is almost done! The missing piece
of the puzzle is now the nylon coated cable. By measuring
about 12? longer than the distance from the horn to the
servo arm, the cable was cut with some wire cutters. The extra
cable will come in handy when attaching to the rigging coupler.
the most challenging part of this entire procedure is attaching
the cable to the rigging coupler and after one or two experiences
turns into a non-event! By simply threading the cable through
the rigging coupler?s hole you are almost 1/4th done!
at least 2? past the rigging coupler and bend the cable
back over itself. Slide one of those brass fittings on the long
piece of cable up to the rigging coupler. Take that ?excess
2+? of cable? and slide it through the brass fitting
(you are now ½ done).
With your nimble fingers bend the shorter piece of cable sticking
out from the brass tubing and loop it around and through the
brass fitting again! You are now 3/4th done.
Pull that looped cable tight and with those pliers crunch (or
as they say in the south ?Mash?) the brass tubing
and you are done. Now that was easy wasn?t it?
You only have to do this three more times.
The other side of the rudder was done the same way. Now you
have a rudder that is complete with two strands of cable going
Next task will be to fish the cables through the fuselage
to the rudder servo which should be mounted in the center
of the fuselage. There are a couple of ways of doing this:
thread the cable into the fuselage and reach in with those
tiny fingers and pull the cable forward; run a piece of Nyrod
through the fuse and slide the cable inside that; make a ?U?
shaped tool out of some wire and reach in and snag the wire
and pull it forward. The choice is yours.
The last major part is to connect the cables to the rudder
servo arm. Remove the arm from the servo (if mounted) and
attach the 4-40 swivel ball link and threaded rigging coupler.
Install this assembly to each side of the dual servo arm and
reattach it to the rudder servo.
the rudder in neutral by clamping the vertical stabilizer and
is a good time to turn on your radio and center the rudder servo.
Make certain the cables running from the rudder are not tangled
together or wrapped around a servo extension. Take each cable
and loop it through the rigging couplers like you did on the rudder,
pulling the cable tight, but in all honesty when finished the
cable will probably be somewhat lose but that?s O.K. for
now. Finish by crimping the brass connectors.
Probably one of the cables are not tight ? maybe both, so
remove the 4-40 swivel ball link from the Dual Servo Arm and hold
the rigging connector with pliers, and screw the ball link clockwise
a couple of turns. Re-install the servo horn on the servo arm
and see if the cable is tight, if not, repeat the process until
the cable is firm but not excessively tight ? after all these
two cable will be pulling on your rudder servo?s drive train
100% of the time!
So you are done with installing a Pull-Pull system on your plane.
There won?t be any flutter because both sides of the rudder
are under tension all the time ? giving you precise control
on the one flying surface that doesn?t stall!
Duty Dual Pull-Pull System .91 & up $20.79
Dual Servo Arms $9.99
Dual Servo Arm $9.99
Duty Clevis Horn System
Pull-Pull System $10.08
over 40+ years, I have never had a Du-Bro product fail in
its job. The quality of both the Dual Servo Arm and the
Pull-Pull system lives up to their high standard. The use
of these products relieves my worry about a cheap part failure
and the result costing me of a giant scale aircraft. This
product does as is advertised and does it well.
The comments, observations and conclusions made in this review are solely with respect to the particular item the editor reviewed and may not apply generally to similar products by the manufacturer. We cannot be responsible for any manufacturer defects in workmanship or other deficiencies in products like the one featured in the review.