This shows the location of the line
guide based on the model’s CG
and planform. You want 3° of line
rake for the starting position of
the line guide on the first flight.
Grant Hiestand’s 1/3-scale Spacewalker was built from a Sig
Manufacturing kit, weighs roughly 19 pounds, has an E-flite Power
160 electric motor, and has a speaker system from Model Sounds
Incorporated that sounds like the full-scale aircraft’s Continental engine.
Draw a line on the plans that is
90° to the CG of the fuselage
The flying lines will form a straight
line between the handle and the
CG through the line guides
Offset = .052 x half
wingspan of model
building. No matter what size you want to fly, there is an
electric motor that will provide sufficient power.
CL Scale rules allow for glow engines up to 1.25 cubic
inches and electric power is limited to 42 volts. The largest
engine I have flown with is a . 90 size. I haven’t yet found a
reason to fly with a 1.25-size engine.
One item judged during competition is realism. The judges
look to see if the model is flown similar to how the full-scale
aircraft would be. In addition to the takeoff run, landing, and
flying, it also includes the engine’s sound. A four-stroke engine
closely matches the sound of the full-scale aircraft. Electric
power is quiet and does not sound anything like the full-scale
aircraft’s engine, so expect a point deduction in realism if
flying with electric power.
There are sound modules with
a speaker that can be added that
work with the speed control and
create the desired scale sound.
Grant Hiestand has flown his
Spacewalker with a speaker that
sounds like the Continental engine
on the full-scale aircraft.
Electric power requires that
electronic controls or 2. 4 GHz for
the throttle are used because the
ESC can only plug into a receiver to
Converting to CL
You need to understand how to
position the line guide before flying
the model. Because you will likely
convert an RC kit, plans, or an ARF
to CL, you will not have instructions
for where to locate the line guide.
Mark the location of the center
of gravity (CG) along the centerline
of the fuselage, then extend a
line to the wingtip that is 90° to
the fuselage’s centerline. Offset the line aft of that line by
multiplying half of the model’s wingspan by .052 to get a 3°
line rake. This will make the model’s nose point outward from
the circle during flight. See the figure that shows how to locate
the line guide.
The vertical location of the line guide must also be
determined so the model remains level in flight. If the line
guide is too low, the aircraft will roll to the right after it takes
off. If the line guide is too high, it will roll to the left.
One trick is to make a set of dummy lines and hang the
model from the garage ceiling. As viewed from the front, the
wing should be vertical. If looking at the airplane from the top,
the nose should be pointed down by 3°.
Always make sure you have an adjustable leadout guide on
a larger model so you can move it forward to decrease the line
tension, or move it aft to increase it. Trimming the line guide
ensures that you have enough line tension, but not so much
that it pulls you over.
I have not mentioned the position of the bellcrank because
it has little to do with trimming the model. The line guide
location, overall weight, and CG will determine how much
line tension you will get. I typically put the bellcrank’s center
bolt 1 inch behind the model’s CG. I use a 4-inch bellcrank for
the larger models, and a 3-inch one for smaller models.
The model will also need some wingtip weight. For RC, the
model needs to be balanced along the fuselage’s centerline. CL
models need weight in the right wing to counteract the line
What about a rudder to keep line tension? I have multiple
models with zero rudder offset and several models without
any rudder at all. I mount the rudder with some stiff hinges so
it can move, but it has zero offset.
25 Model Aviation JUNE 2015 www.ModelAviation.com