visitor Barry G. (of Australia) wrote to ask to have the article
for Claude McCullough's Fletcher FU-24 scanned and posted. It appeared
in the September 1971 edition of American Aircraft modeler. The
Fletcher is an Australian crop duster that looks and flies more
like a sport plane than a crop duster. A unique feature of the FU-24
is its all-flying horizontal stabilizer (aka stabilator). The plans
are high detailed with lots of good fodder for scale trimmings.
There are lot of names credited on the plans. Claude McCullough
drew them, with attributions given to Harld De bolt, Dick Grahm,
Bill Hannan, Gerald Barden, and Maj. L.G. (Don) Halls for contributing
Interestingly, Mr. McCullough lived in Ottumwa,
Iowa, at the time, which is the hometown of Corporal Walter (Radar)
O'Reilly from the M.A.S.H. television show!
This down-under duster from Australia offers every desirable
feature a scale modeler could ask. Plenty of details can be added,
structure is simple, flies like a trainer.
By Claude McCullough
Graham first noticed the possibilities of the Fletcher for RC scale
when it appeared in a spark plug ad! To find more data, he contacted
the FU-24 Project Engineer for the Sargent-Fletcher Co., Gerald
M. Barden, who turned out to be a modeler of over 40 years standing
and was glad to assist with the project. Design rights for the aircraft
had been sold to Air Parts, Ltd., of New Zealand, and Barden had
spent some time there helping get it into production and test-flying
the first 42 off the line.
Only a few drawings were still
available in the U.S. and the "General Arrangement" unfortunately
proved to be like many factory drawings of this type - very general,
not really meant to be an accurate outline but more a pictorial
representation. It was fine for some purposes but not for modeling.
In this case, the side view did not match with the top, and Dick
became discouraged with the idea of presenting this to a judge as
proof of fidelity.
However, I couldn't get the Fletcher's
trike gear, generous area of thick wing, and functional lines out
of my head and mentioned this interest to a kindred scale enthusiast,
Major Langdon Halls. In quick succession, he located FU-24's at
Armidale, Australia; photographed and measured them on a bitterly
cold day; drew a set of his superb 3-views (subsequently published
in Australian Modeler); and supplied me with copies. With such friends,
it's no wonder scale is a growing fraternity.
Since the Bremen World Champs and the first International RC Scale
meet were coming up in a few months, the Fletcher looked like an
ideal subject. Its non-complex lines, with no compound curves, would
make for speedy building and planking. To meet. the FAI 11-lb. limit,
I sweat over each piece during construction, but by using restraint
with the ply and epoxy and building with Sig Contest balsa wood,
the ship eventually turned out just under 10 lb.
Real plane is surprisingly large, using a big 300-hp engine.
Even with full load, it gets airborne quickly, works efficiently.
Photo was taken two years ago, but the Bantam Twin engine is
just now becoming available. Note mounting structure.
Dusters are not meant for speed, so it all hangs out. Brake
line must be easily serviced in the field. Box could open by
Carefully concealed is a stock Breiten nose gear. Fork built
up with balsa, shim stock, and Epoxolite. Du-Bro wheel fits
A championship model requires complete interior detailing. Plastic
pilot wears hand-made uniform.
Wide scale fuselages permit several servos to hide in wing.
Auxiliary servo for duster dumping or electric brakes.
Cockpit floor at left recesses into wing center section. Radio
receiver mounts by grommets to servo mount tray.
Rear quarter view shows off the simple lines. Flaps down for
quick takeoff and steady slow flight when working.
nose proved an ideal test bed for Ben Shereshaw's experimental 60
twin-cylinder engine, now going into production. The Bantam lays
to rest old theories that said a twin wouldn't have good power or
idle. It pulls a big model around with ease. As for idle, at Bremen
I hadn't had time to install brakes but was able to come to a complete
stop without them for proto taxi. The Fletcher also made the only
touch and go of the meet. Scale has long needed a twin but this
engine also should find plenty of use elsewhere, since the vibration
level won't shake radio equipment apart. Use of a standard 60 in
the model will require extending the head through the cowl, side-mounted
The all-moving stabilator of the Fletcher was
eyed with a little tredpidation, since some attempts to use these
on RC jobs haven't worked out well. However, in this design the
control response proved just about right, without any deviation
from scale or resorting to servo movement reducing gimmicks. Luckily
the plane has a deep enough fuselage under the tail to get in a
sufficiently long control horn (make it as long as is possible).
Also keep in mind that an adjustment of the clevis has a much greater
effect than in a conventional stab-elevator setup. After the last
test flight at Frankfurt before the Bremen contest, we applied a
little too much correction for a slight nose down tendency and overdid
it, causing some trim problems during official flying. (Some time
after the International meet, it was discovered that the computer
goofed and the Fletcher should have been placed sixth instead of
seventh as announced.)
The only readily available published information on the Fletcher
appeared in the May 1962 Flying Magazine. It features a pilot report
and history on the aircraft, along with photos of the utility version
which is equipped with windows and seats for passengers. This would
be an interesting modification of the basic model for those who
don't want to get into the functional detail of the duster.
Don Halls has loaned me the negatives of his fine pictures in
color and black and white and I'll undertake supplying copies at
cost. Send a self-addressed, stamped envelope to Claude McCullough,
Rural Route 5, Ottumwa, Iowa 52501, for complete information. There
is no substitute for having photos of the prototype for accurate
details and this set of shots shows close-ups of the landing gear,
cockpit, cowl, dust box, etc., as well as views of the complete
Sig will assist in duplicating the model by providing
the big canopy and some small moldings for lights and scoops. Cost
is $3.25 plus 50 cents postage. Mark the item: "Attention: Maxey
Most of the necessary construction information
is on the plan. The only unusual area is the nose section which
requires some ingenuity to get everything shoe-horned in and still
leave some structure. A complete cockpit with reasonably thin walls
also must be accommodated. The design worked out well, as shown,
but care must be taken to join solidly all joints between the ply
and balsa sandwich which forms the sides of the nose and the rest
of the fuselage. All the corners in this area should be reinforced
with epoxied spruce angles.
Do not omit the cockpit floor
since the channel strength formed by the sides and bottom is necessary
to keep the structural integrity. Note particularly that F-1 is
not attached until after the landing gear, tanks, rear cowl attachment
blocks and exhaust augmenter tubes are installed.
of the nose construction not shown on the plans depends on the engine
being used. Where the mounting bolts for the motor or motor mounts
go through the firewall F-1, put a full length 1/8 x 3/8" ply doubler
on the rear side. Two pieces of 1/8" ply are then hand-fitted into
the area between F-1 and F-2, one end in the corner formed by a
side of the mounting bolt doublers and the other end epoxied against
F-2 in the area between the tank holes. (See photo of nose with
cowling off.) The depth of these pieces is determined by the available
space. With the Bantam, one side was full depth, the other only
partial because the thrust angle puts one tank in the way. The final
result is very strong.
The tanks can be inserted from the
cockpit but it is not easy and a few comers may need tapering and
rounding. Since the tanks go in easier than they will come out,
do painting and any other interior work before putting them in.
It is seldom necessary to remove them. A bead of Sig Epoxolite is
formed around the tanks on the front of F-2 to prevent fuel seepage
into the cockpit.
To avoid a lot of oil and fuel gook
in the engine compartment, use mufflers directed right into the
exhaust augmenter tubes. Since positioning of the mufflers will
depend upon the engine, holes in F-1 to pass them must be custom
cut to fit. If mufflers are not used, some holes in F-1 are still
needed to allow cooling air to exit.
hinges were made of telescoped brass tubing so that the unit could
be removed for shipment or detached for repair in the event of crash
damage. To line up the two outer tubes for imbedding in Epoxolite,
run a piece of dowel between them. When they set up, saw a piece
out of the dowel so it can be removed. Another long straight dowel
should be used between the 1/8" nylon bearings on each side of the
fuselage when mounting them to insure the stabilator will go on
A female mold for the fiberglass cowl is cast in
plaster, using a pattern which is made from balsa block, then coated
with resin and polished. For casting, build an open-topped plywood
box which is a little bigger than the wooden pattern and may be
knocked down easily. Place the pattern in back side down and fill
the box with plaster. When it is sufficiently set, turn the box
over with the bottom side up and pull out the nails holding it together.
This will expose the back of the pattern. Screw a large clothes
line hook into it the balsa and pull out, keeping in mind the taper
of the sides requires a slight angle. Coat the cast with release
agent and paint the inside with one coat of resin. When dry, add
another coat. When tacky to the touch, lay in a layer of fine cloth
and give it another coat of resin.
I've ruined too many
cowls trying to get them out of deep molds, so I no longer try.
Plaster is cheap and a mold easy to make. Cut into all four sides
with a saw nearly to the cowl and split the mold open with a hammer
and chisel. Carefully sand the cowl to remove the release wax.
The number of stringers used in the fuselage are limited
to keep the weight down. As the covering ages, the planking sinks
in a certain amount. The stringers shown in the plan are used on
the model but, for the negligible weight gain involved, the number
could be increased, particularly on the fuselage top. Key stringers
could be made from spruce to insure retaining a more accurate and
In a day of quick coverings and finishes,
it is still hard to beat the quality of a silk and dope application
for a scale model. I covered every part with silk and filled the
grain with two heavy coats of Sig Sanding Sealer, sprayed on and
sanded between coats. Spraying prevents brush marks and other uneven
spots and gives a perfectly smooth base for the color dope. It also
requires less filler coat because there are fewer ups and downs
Before the color dope is applied, much of the
surface detail (rivets, panel lines, stiffening crimps, etc.) should
be added. Panel lines were scribed into the fillercoat surface with
a replaceable-point scribing tool, using a new, sharp point. For
information on the rivet method, stiffener crimps and other fine
detailing techniques, see the RC Scale section of the "Where the
Action Is" in AAM for the past several months, as well as future
Only two sprayed coats of Sig Supercoat White dope
were necessary to cover the white surface of the Sanding Sealer
fillercoat base. Supercoat has a low-shrink base which helps control
warping and planking distortion. Colors of the markings and lettering
are shown on the plan.
Most of the lettering was done with
Letraset rub-on dry decals obtainable from art supply stores. A
little practice is necessary to get these on the model without rubbing
so hard as to make an indentation in the wood.
them out on an old model. I got good results with a ball point pen
as a tool, using very closely spaced, actually overlapping, strokes
and light pressure. Don't be in a hurry for the letter to separate.
Take some additional care with the larger letters so their shape
is not distorted during application. It helps to work from center
to ends, following the letter and not going across open spaces to
another part of it. So does pressing down on the letter firmly with
a finger before beginning to rub. Although decal directions specify
using the entire sheet intact, it seemed easier to cut out each
letter with as much border of mounting material as .possible, especially
in the larger sizes. Spray clear dope over the decal letters with
great care, using only a haze at first and allowing each coat to
dry until some coverage is built up.
The following Letraset
sheets were used: 26-60CN, fin numerals; 6-96L, "ap" trademark;
26-36CLN, No Step on gas tank; 26-30CLN, No Step on flaps; 54-36CN,
Fletcher FU-24 on nose; 75-42CLN, Armidale on fuselage. The large
wing registration letters were marked on the wing with a soft pencil
from paper patterns, outlined with a ruling pen filled with black
dope and filled in by hand.
Balance point for the model
is between 3 1/4 and 3 1/2" back from the leading edge of the wing.
Setting the stabilator angle is too critical a job to be done by
eyeball. Get a big, flat piece of corrugated cardboard and make
a template from the side view of the fuselage. The template can
be placed against the flat bottom of the scale NACA 4415 airfoil
and provide a cradle back at the tail that will fit the profile
of the stabilator to push it into the correct relationship. Then
give the clevis an extra half turn of up trim for good luck. It's
better to have a little too much up than down on a test flight.
I'd be glad to try to answer any questions about construction
and would like to see some photos of other Fletchers.
Fletcher FU-24 Plans
<click for larger
Fletcher FU-24 Plans
<click for larger
The AMA Plans Service offers a full-size
version of many of the plans show here at a very reasonable cost. They will scale the plans any size for you. It is always
best to buy printed plans because my scanner versions often have distortions that can cause parts to fit poorly. Purchasing
plans also help to support the operation of the Academy of Model
Aeronautics - the #1 advocate for model aviation throughout the world. If the AMA no longer has this plan on file, I
will be glad to send you my higher resolution version.
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Posted August 29, 2012