The line slider components are probably available in most modeling workshops, except for the
carbon-fiber arrow shaft and the neodymium magnet.
A view of the aft end of the assembled line slider.
In keeping with the how-to theme of this issue of Model Aviation, I will feature a detailed description of the
new line slider that I have incorporated
into my electric Seafire project. The
details of the Seafire will continue in my
I had originally intended to let the
sketch outline and photos in the last
column suffice because there are
certainly plenty of innovators among our
modelers who could fill in the details.
This how-to opportunity changed my
mind, and I’ll expand the details enough
to allow you to duplicate my efforts
without so much of the head scratching
that I’ve gone through.
The most significant feature of
Control Line (CL) Navy Carrier flying
that distinguishes it from other events
is slow flight. Our scale models are not
unique. Flying fast is a common aspect
of many CL competition events. Our
landings are more restrictive than other
events, but not particularly different in
concept. Slow flight, however, with its
propeller-hanging flying style, sets Navy
Carrier apart from the rest of CL flying.
The key feature of our models that
makes our extreme slow flight possible
is the line slider. With the model hanging
at a 60° angle and flying at speeds of
less than 10 mph, centripetal force
is completely inadequate to provide
sufficient line tension for control.
The line slider allows the modeler to
move the leadout position to the rear
and point the fuselage of the model
(and the engine) toward the outside of
the circle. The engine offset allows the
engine thrust to provide the necessary
line tension for adequate control.
The slider allows the model to fly
high speed in the conventional manner,
I wanted my new slider design to
keep both drag and weight low. Drag
reduction took two approaches. First, the
slider is aligned parallel to the fuselage
(and airflow). Second, it is a relatively
low cross-section, in a single unit, with
few protrusions to disrupt airflow.
Although many Carrier modelers
angle their sliders inboard so that the
low-speed leadout position is closer to
the fuselage, I prefer to move the entire
slider inboard and keep it aligned with
the airflow. The line pull is adequate to
control torque during high speed—even
if the leadout position was at half of the
distance to the wingtip.
Managing torque on takeoff has
never been a problem for me, and the
left-hand rotation of an electric motor
(as well as some internal combustion
engines) makes this a nonproblem. The
inboard position also reduces the need
for weight in the outboard wingtip.
In the April issue, I described my
method for slotting the carbon-fiber
tube (arrow shaft) that is one of the
main components of the slider. I also
described the actual slide/line guide.
The retainer mechanism that keeps
the slide in the deployed position is
a neodymium magnet from Master
Magnetics. Check your local hardware
or hobby store. Many sizes are available.
I used a locally available disk magnet. It
is slightly larger than the arrow shaft, so
I had to improvise on the attachment. I
have one cylindrical magnet that would
have fit inside of the arrow shaft, but
because I could not locate a duplicate
nearby, I opted for something that my
readers might be able to easily find.
The magnet is mounted inside of a
thin-wall aluminum tube (another arrow
shaft) that is tightly fitted around the
magnet. That tube is glued over the end
of the main tube and has a streamlined
balsa plug inserted behind the magnet.
A few years ago, I stopped at a local
archery shop to purchase a few shafts
for modeling purposes, along with some
archery supplies that I needed. I filled
a small box with the discarded pieces
of shafts that were left after cutting the
shafts to length in the arrow-making
process. That box has been a useful
source of carbon-fiber and aluminum
tube ever since.
The mechanism for holding the slide
at the forward position is fashioned
from a piece of thin-wall brass tube
that is approximately 3/16 inch in
diameter. I crushed it in a vice with
a sheet-metal filler that was slightly
thicker than the slide material.
I cut off one edge with a Dremel
cutting wheel to form the streamlined
channel shown, and mounted the channel
125 Model Aviation JULY 2017 www.ModelAviation.com sponsored by HOW-TO issue
Line slider how-to
by Dick Perry
CONTROL LINE NAVY CARRIER