I HAVE BEEN building and flying my father Dick’s profile 1⁄2A
Control Line (CL) airplane designs for more than 25 years. They are
easy to build, and with only a small investment in balsa, dope, glue,
and an inexpensive engine, you can have a great-flying aerobatic
airplane. You don’t need a large field to fly on; we generally fly at the
local school yard.
We’ve taught many of the neighborhood kids how to fly the
“direct connection” way with these models. Former CL world Stunt
champ and this magazine’s aeromodeling editor Bob Hunt has even
performed the entire Stunt pattern with dad’s Corsair 1⁄2A design and
likes flying these airplanes for fun.
Even though dad has primarily been active in Radio Control (RC)
for many years, he has always enjoyed CL flying for a fun change of
pace. Dad was flying CL back when his RC systems had vacuum
tubes (whatever they are) and high-voltage batteries!
With an 11-year-old son ready to learn the basics of aerobatic CL
flying, I talked with dad about some fresh designs. In the past we had
collaborated on a 1⁄2A F-86 and MiG-15. Our collaboration on that
project and this one was via long distance; I live in Southern
California and dad lives in New Jersey. Using the telephone, Email,
and priority mail, we are effectively able to develop these
projects. With a digital camera and E-mail, dad can “see”
construction progress instantly.
The F-86 and MiG-15 are fun to fly; however, we needed some
new airplanes because they were showing signs of wear and tear from
many training flights.
My son Matthew is actually the fourth-generation Sarpolus to fly
CL. When dad was a young teen learning to fly CL, my grandfather
got interested in what dad was doing and decided to try it. He went to
the local hobby shop and bought a Lil’ Duper Zilch kit and a frontintake
Forster .29 engine. He read the instructions on the plans and
some magazine articles about CL flying. He quickly had the airplane
built and was ready to fly.
Dad had crashed quite a few airplanes while having difficulty
learning inverted flight. Grandpa brought his newly constructed
model out to the field, and, to the amazement of dad and his friends,
was immediately flying with no trouble! He mastered inverted flying
in a couple of flights without crashing. After that, grandpa gave the
airplane and engine to dad and never flew CL again. After being
shown up by his father in front of his friends, dad quickly mastered
inverted flight!
Having built so many military airplanes, I looked at generalaviation
aircraft. Small civil airplanes aren’t modeled very often—
especially by CL modelers. I have always liked the looks of the
Mooney; its unique forward-swept fin and wing trailing edges
instantly identify this aircraft. The Beechcraft Bonanza is also terrific-
Beechcraft
February 2003 39
Mooney
and
Bonanza Designs inspired by two of the most popular private airplanes
■ Rick Sarpolus
Mooney
Beechcraft Bonanza
Mooney and Beechcraft Bonanza
Type: CL 1⁄2A profile sport
Wingspan: 291⁄2 inches
Engine: Norvel BigMig .061
Flying weight: 7 ounces
Construction: Sheet balsa and plywood
Finish: Butyrate model-airplane dope
02sig2.QXD 11.21.02 2:17 pm Page 39
40 MODEL AVIATION
looking, with its classic lines and that neat Vtail.
These airplanes are some of the most
recognizable civil aircraft ever produced.
Both have legions of loyal fliers; check out
the many Web sites devoted to each. As a
youngster I got to ride in Bonanza and
Mooney aircraft that belonged to my father’s
friends, and I remember looking on both as
great airplanes; it was a thrill to ride in them.
These model designs are not specific
Bonanza and Mooney models; they are
generic airplanes as they would be
recognized by most aircraft enthusiasts.
Introduced in 1947 with its distinctive V-tail
design, the Bonanza is still in production
today but with a conventional tail surface
since 1982. The Bonanza is generally
regarded as sleek, fast, and high
performance.
The Mooney Aircraft Company was
founded in 1946. The Mooney’s vertical tail
design has endured through the years and is
as recognizable as the Bonanza’s V-tail. Still
in production today, Mooneys are also
regarded as clean, sleek, high-performance
airplanes.
I called dad and suggested that we build
these two airplanes; he thought it was a good
idea. Searching the Internet I could not find a
reasonable three-view of either airplane to
enlarge, despite the large amount of
information and photographs available. After
another call to dad, two three-views copied
from his vast airplane-magazine collection
were in the mail. He also recommends Bob’s
Aircraft Documentation (3114 Yukon Ave.,
Costa Mesa CA 92626) for three-views,
pictures, etc.
I followed the basic layout dad originally
developed for these 1⁄2A all-sheet-balsa Stunt
models which has been proven through the
years. The wingspan is approximately 30
inches, the fuselage length is roughly 23
inches, and the wing area is approximately
170 square inches, with appropriate wing and
tail moments. The blown-up three-views
were easy to “stretch” into this layout, and
they look great as profile Stunt airplanes.
The Bonanza’s V-tail was tricky, but a
solution was developed with yet another call
to dad. The pushrod runs down the side of
the airplane, in the usual fashion, to a control
horn on one side of the Bonanza’s tail.
Through a slot in the fuselage underneath the
tail, another pushrod is connected to the other
side.
One addition after most of the pictures
were taken was the pushrod brace on the
fuselage side, halfway back to the tail. It’s a
nylon control horn like those used on the
elevators, and it’s mounted with two small
screws in a piece of 1⁄16 plywood inset in the
fuselage side. This brace prevents pushrod
flexing with the V-tail setup.
Also because of the V-tail, additional
engine offset and leadout sweep were utilized
to compensate for the absent fin offset. These
changes to our traditional layout ensure that
the airplane stays out on the lines well. The
Bonanza with its V-tail flies just as well as its
sister Mooney with its conventional tail.
We used Cox .049 Tee Dee engines in
these small models for many years. They are
popular and have plenty of power to fly these
airplanes. This time dad suggested that I look
at the Norvel engines; he had tried a few and
found them to be reliable. I quickly navigated
to Norvel’s Web site—www.norvel.com (or
[800] 665-9575)—and ordered two BigMig
.061 C/Ls, extra glow plugs, and two starter
springs. Within a couple of days they arrived
on my doorstep.
The Norvel engines have proved to be a
delight. Easily started, they run flawlessly
throughout a typical aerobatic flight. The
Norvels’ extra power also allowed us to
lengthen the lines on which we fly. Instead of
the 35 feet we had been using with the Cox
Tee Dees, we are able to fly on 42-foot lines,
which give us a 44%-larger “flying surface”;
this makes these airplanes even more
enjoyable to fly and aerobatics easier to
practice.
CONSTRUCTION
Construction is straightforward. The
fuselage is made from 1⁄4 balsa with 1⁄32
plywood doublers over the nose section for
added strength. The doublers cover the 1⁄4
square hardwood engine mounts in the
fuselage. Wing and tail surfaces are 1⁄8
balsa. We edge-glue whatever widths are
on hand to get the sizes needed.
Medium-weight, firm balsa is fine;
anything softer breaks too easily. Heavier
pieces will survive crashes better, but they
can add too much weight. I have seen these
airplanes bounce back from many hardlooking
crashes on grass fields. If they do
break, you can generally get them back in the
air quickly with five-minute epoxy.
The hardware is standard hobby-shop
fare. Our favorite shop is Tony & Addie
Hobby Lobby (3512 W. Victory Blvd.,
Burbank CA 91505; Tel.: [818] 842-5062)
for its old-fashioned hobby-shop feel; Tony
& Addie’s has been at its Burbank location
since 1951! The store is usually full of
experienced modelers hanging around, and
you can count on wise advice and great
service from Tony Naccarato. He stocks
everything the CL modeler needs.
Pick up a two-inch bellcrank, bolt-on
small nylon horn, 1⁄16-inch-diameter wire for
the pushrod, 0.025-diameter wire for the
leadouts, and a small metal fuel tank at your
favorite shop. The Perfect brand of fuel tanks
has been around for years. I have a few I got
from dad that are more than 30 years old! I
use cloth over-under hinges glued on with
old-fashion model-airplane glue—techniques
learned from dad when I was a young
builder.
Assembly of almost everything is done
with five-minute epoxy. Shape small fillets,
from epoxy mixed with microballoons for
easier sanding, around the wing and tail
surfaces with your finger. These fillets add
strength and improve the appearance.
A jigsaw makes it easy to cut the parts,
but if you don’t have one an X-Acto knife
works fine for everything except the engine
mount. Cut up the plans for patterns, and
trace the outlines onto the balsa pieces you
have gathered and edge-glued as necessary.
Assembly: Start assembly with the fuselage,
gluing the engine mount in place. Glue the
plywood doublers on, and cut the slots for the
wing and tail surfaces. To install the wire
hook that holds the gas tank on, cut a slot
through the outboard doubler; epoxy the
hook in place along with a plywood filler
piece to fill the slot. Before gluing the
flying surfaces in place, be sure to
Here are the component parts for the Bonanza ready for
assembly. These are easy-to-construct models.
Here are the Mooney parts. Each of these models can be built in
a few hours, but will provide many hours of fun.
Photos courtesy the author Graphic Design by Lydia Whitehead
02sig2.QXD 11.21.02 2:17 pm Page 40
carefully mark and drill the holes for mounting the engine.
Separate tip sections are glued to the ends of the wings to resist
warps. Even if some warping occurs in the completed model, it
doesn’t seem to affect the flying qualities. Sand the edges of the
flying surfaces round. For the Mooney, glue the rudder on with
the fin offset approximately 1⁄4 inch toward the outside of the
flying circle. For the Bonanza, glue the tail surfaces together at the
angle shown on the plans.
For final assembly of each airplane, slide the wing through the
fuselage slot and align it at right angles with the fuselage. Hold it
in place with pins and tack it in with cyanoacrylate glue (CyA),
then use epoxy to make a strong joint, adding fillets as mentioned
earlier.
Glue in the tail surfaces, being careful to properly align them
with the fuselage and wing. Glue a small lead or solder weight
under the outboard wingtip, bellcrank mount, and leadout guides
on the inboard wing.
Attach the bellcrank with a small screw. The nylon control
horn is mounted to the inboard elevator on the Mooney and one
each on the Bonanza’s V-tail surfaces. On the Mooney, fashion
the pushrod from the 1⁄16-inch-diameter wire. Be sure to have the
proper length so that when the bellcrank is in the neutral position,
the elevator is too, and you get equal up- and down-elevator
movement. For the Bonanza, the pushrod is trickier as described
earlier. Take a look at the plans and photos.
Finish: These airplanes were finished with butyrate dope. Dad has
been using it for more than 40 years; I can remember the smell of
butyrate dope wafting up from the basement, much to my
mother’s chagrin.
After sanding the entire airplane well, put on a coat of clear
sanding sealer, sand well, then apply four or five coats of clear
dope, sanding lightly between coats. The goal isn’t a perfect
finish; filling in all the grain would make the airplanes too heavy.
The models were covered with a few coats of white. Most civil
aircraft are white with some trim color. The trim colors on the
Bonanza and Mooney are representative of the types of color
schemes that might be seen at the local airport. Adding lines and
canopy areas in light blue finishes the look. The finish is
completed with a few sprayed-on coats of clear dope.
Add the engine, tank, control hardware, and check for proper
balance. If nose weight is needed, you can drill a 1⁄8-inch hole in
the front of the fuselage under the engine mount and glue in a
length of heavy solder or large steel bolt.
The Mooney did turn out slightly tail-heavy. The nose has
been lengthened some on the plans for both models, so they
should balance properly for you with no added weight. Mount the
Mooney’s engine with a couple of extra washers under the front of
each engine-mounting lug for a few degrees of out thrust to keep
the lines tight while flying. For the Bonanza, small plywood
wedges were added under the engine to get even more out thrust.
February 2003 41
Bonanza V-Tail Linkage
The Bonanza model’s V-tail requires a special linkage treatment.
Each elevator has a control horn, and the pushrod is spliced at
the rear to allow individual elevator movement with no binding.
The elevators are shown in the “up” position.
The elevators are shown in the “down” position.
The spliced pushrod is visible. The slot in the fuselage allows the
secondary pushrod to actuate the far-side elevator.
Here are the two assembled airframes with the control
systems trial-fit. The next step is finishing.
02sig2.QXD 11.21.02 2:18 pm Page 41
This, along with some additional leadout
sweep, makes up for the lack of an offset
vertical fin.
Our 42-foot lines are .008 stranded cable
lines; .012 lines also work fine. The stranded
cable lines seem to resist kinking and
breakage better than the solid lines. When
flying, we always hand launch. We have the
launcher keep the lines tight and point the
airplane toward the outside of the circle as he
or she takes a few steps forward and releases
the model in a level position with a forward
arm motion.
Mooneys, Bonanzas, and other similar
general-aviation aircraft are used for personal
transportation and pleasure flying—not
aerobatics. However, these Mooney and
Bonanza models will handle almost any CL
Stunt maneuver you can throw at them! So
go ahead and enjoy these fun models’ great
Stunt and sport-flying qualities.
I’m dedicating this article to my wonderful
father, friend, and inspiration Dick Sarpolus,
without whose help this article would have
been impossible. MA
Rick Sarpolus
4303 Countrymeadow St.
Moorpark CA 93021
42 MODEL AVIATION
The author (L) and his son Matt (center) visited Tony Naccarato at Tony & Addie Hobby Lobby in Burbank CA with their new models.
This is the business end of the Bonanza. Both models are
powered by Norvel BigMig .061 engines. It’s a clean installation.
Perfect-brand one-ounce tanks were used on both models. These
classic tanks are available from Brodak Manufacturing.
02sig2.QXD 11.21.02 2:19 pm Page 42
