ENGLAND 1924: Just as the sun was peeking over the horizon,
two dark sedans marked with the name and logo of the Bristol
Aircraft Company rolled up to a hangar. With the mist still rolling
over the grass field, men climbed out of the automobiles. Their eyes
were red from a late night of work, but their spirits were high with a
sense of optimism.
The hangar doors were rolled back creaking with protest, revealing
a trim silver monoplane of very modern design. Named the Brownie, it
was the Bristol company’s latest entry in the efficiency trials.
Powered with a Bristol-built 32-horsepower Cherub engine, the
Brownie even had sets of wings for the several different tasks. This
day was the speed task, and the shorter set of wings had been fitted.
For the next hour the tired mechanics went over each adjustment
and fitting, preparing the Brownie. When all was finally proclaimed
ready, the men moved into place to start the little Cherub.
“Switch on,” then “clear!” rang out in the morning still, as the
Brownie’s propeller was pulled through for a prime. The carefully
prepared engine came to life after two flips, blowing smoke from the
short stacks and crackling the sounds of a cold engine. The Cherub
Classic-era low-wing monoplanes have a certain charm about
them—on the ground and especially in flight.
n Dave Robelen
Charming British monoplane for
geared Speed 400 motors.
April 2001 15
Geared Speed 400 motor provides go-power for this model. Note
simple, accessible/serviceable mounting arrangement.
The receiver is easy to get to through the wing-mount area
access in the fuselage. Everything is well-cushioned.
The Brownie’s front-end details include simulated Bristol Cherub
engine cylinders. The author used a 9 x 5 propeller.
The aileron servo mounts in the wing center-section. The
pushrods are joined with a piece of soldered brass tubing.
The Brownie’s nose takes on a sleek, streamlined appearance
with the cowling in place. It’s a clean, functional model!
16 M ODEL AVIATION
was smoothly puttering at idle minutes later, and all had been
checked one last time.
Climbing into the snug cockpit, the pilot was determined to
push Brownie to the limit and let it show its stuff. The takeoff
went smoothly on the grassy field, and the climb was impressive
for such a small engine. The pilot signaled readiness for the first
run after two laps around the field to warm the engine.
Diving for speed, the Brownie accelerated to a most
impressive velocity. The pilot leveled off with the little
Cherub singing as they rocketed down the course. Pulling up,
the run was repeated in the opposite direction for an average
speed of 70 mph.
As Brownie was setting up to land, hands were being
shaken, backs were being pounded, and the long night was
being forgotten.
Was it really that way? I don’t know the details, but my
imagination can supply plenty as I consider the feat
accomplished that day.
The Brownie kept coming back to my attention when I was
looking for a suitable Scale model for electric power. It was
efficient, it could be built light, and it has the charm found in so
many British airplanes.
Besides, the fields are not exactly crowded with model Brownies!
Photos courtesy the author Graphic Design by Carla Kunz
April 2001 17
Type: RC Scale
Wingspan: 44 inches
Motor: Geared six-volt Speed 400
Functions: Rudder, elevator, aileron,
motor control
Flying weight: 23 ounces
Construction: Built-up balsa
Finish: Heat-shrink film
The model presented here is true scale in
all dimensions, but has been simplified in
detail to provide a Scale model that is suited
to the rigors of regular flying.
Even though the model is large for the
chosen motor (a six-volt Speed 400), the
performance is pleasing. The climb rate is
healthy, Brownie will roll and loop with
ease, and the high-speed passes are
downright satisfying!
The model has never shown a tendency
to snap-roll or have unpleasant tendencies in
slow flight. In fact, it has been known to
gain altitude power off in a thermal.
As far as skill required for flying, anyone
who has mastered an aileron trainer could
easily handle Brownie.
The key to this degree of success lies
largely in weight control. At 22 ounces,
Brownie has a wing loading comparable to a
powered glider. With the modern motors,
propellers, batteries, and gearboxes, there is
more than ample power for flights of at least
10 minutes and plenty of time for
maneuvering.
Because of the clean design and
responsive controls, Brownie is not
grounded by a breeze. I have flown the
model comfortably in 15 mph winds.
The issue of weight control is very real
and critical to this project’s success. The
radio control gear does not have to be ultralight
or small; a nice, basic four-channel set
will do. If you have small servos, by all
means use them; every little bit adds up.
“Building light” is as much an attitude as
a technique or skill. One of the worst things
you can do to a proven model is add
“reinforcements” against the possibility of a
crash! Using plenty of heavy epoxy glue for
the same reason is also a no-no.
My model is covered with TopFlite®
MonoKote®; it was probably a heavy
choice, but I am familiar with this material.
If you know of a lighter system, go for it
and let me know what you used!
There is quite a bit of balsa in Brownie,
and proper selection for the various parts is
vital. For reference, a sheet of 1⁄16 x 3 x 36-
inch balsa should weigh 12-14 grams, or
approximately 1⁄2 ounce. To get target
The sides of the Brownie’s fuselage are shown with the 1⁄8-inch-square balsa framing
glued in place. This keeps everything rigid, and it’s light!
The fuselage sides are joined using bulkheads and crosspieces, to form a strong and
torque-resistant unit. This is simple to construct.
Shown are the Brownie’s wing halves prior to being joined. Notice the half-ribs and the
unique shape of the integral ailerons.
Battery access is through a hatch in the lower front section of the fuselage. It makes
battery replacement a cinch! This is a well-thought-out design.
Continued on page 22
22 M ODEL AVIATION
weights for other sizes, multiply by the
difference in thickness.
This grade of wood is not common in
stores, but several mail-order balsa-supply
houses advertising in this magazine can
satisfy your needs.
I use a good hobby grade of medium
cyanoacrylate glue (CyA) for most of the
project. There is also technique here, in
learning to apply enough glue for a secure
joint without flowing excess around.
Scratch-building a project such as
Brownie can be very rewarding—especially
if you keep your standards high.
CONSTRUCTION
Fuselage: Let’s start here to get warmed up.
I spliced three-inch-wide balsa into wider
sheets to make the sides.
The next step involves gluing all the 1⁄8
balsa strips to the sides. Follow the plans
closely, and please make a left and a right!
The sides may be joined in the center
first, with the bulkheads and crosspieces
keeping everything nice and square. Pull the
nose into the front bulkhead, glue, and add
the rest of the forward crosspieces.
The tail cone should be next, working
back to the station where it angles together
sharply. I had to cut through the 1⁄8-inch
strip material, leaving a “V” notch in the
stringers to pull it together.
The top and bottom are sheeted with
1⁄16 stock, with the grain running across
the fuselage. I glued all the short planks
together on the workboard, and sanded
the joints smooth before gluing to the
fuselage.
The front decking needs to be made from
some fairly flexible wood, and it is necessary
to splice the width. Fit carefully, and use
plenty of masking tape when gluing in place.
This is one job where a slower-drying wood
glue does a much better job than CyA.
Mount the landing-gear block and any
remaining sheeting, and sand the whole
works smooth. For reference, my fuselage
weighed 64 grams at this stage.
Cut the cowling from soft balsa block,
splicing if necessary to achieve the
dimensions. An X-Acto™ whittler’s blade
does a fine job of trimming the outside to
shape, and a Dremel® tool is handy to
shape the inside.
I have shown a 1700 series 2.33:1 gearbox
on the plan, which works very well for me.
This is a good time to fit the mounts and make
changes if you are going to use a different unit
(a Mini Olympus gearbox would do fine).
Tail Feathers: These are simplicity itself.
Find some 3⁄16 balsa sheet that weighs 36-38
grams/sheet, and cut the parts. Depending
on your wood width, you may have to do
some splicing.
Be sure and sand the taper in the
elevator, and bevel the edges of the
controls as shown.
My tail assembly weighed 21 grams at
this stage. Set it aside for later.
Wing: The wing involves more parts-cutting
than the fuselage, but it can still go rather
quickly. Take the plan to an office copier and
make reproductions of the rib shapes to be cut.
All the ribs except the root rib are
made from light 1⁄16 balsa. If you can
find some of the quarter-grain stock, so
much the better.
Since we are dealing with a tapered wing,
it is necessary to cut several sizes of ribs. Cut
two balsa blanks and one paper pattern for
each rib size. Sparingly affix the two sheets
with a glue stick, with the pattern on top.
Remember to apply the glue sparingly! If
you use too much, you will have a nice,
thick rib with a permanent pattern. A few
stripes is plenty.
Cut the ribs shortly after gluing and
pull apart, and things should go nicely.
Proceed until you have a full set of ribs.
This is a good time to mark and drill
for the aileron wire bushings. I used slices
of Sullivan Products tubing for a thin
throttle cable housing.
The wing spars are the only place I
used moderately firm wood. Not hard—
firm. Mark and slice a set of spars, and saw
the plywood dihedral braces.
The 1⁄4-inch-thick leading edge should be
cut from soft balsa, slightly wider than the
finished size. The same goes for the aileron
spars; measure the depth from the ribs at the
ends and cut slightly oversize. Round the parts
by cutting the tip pieces from light 3⁄16 stock.
Assemble the wing in two panels.
Start by pinning the spars down along
the trailing edge, then gluing the main
ribs in place. Clamp the leading edge to
the ribs, and glue.
Assemble the tips, noting that the rear
of the tip is shimmed up to the center of
the aileron spar. Add the nose ribs, and let
it dry a bit. Glue the dihedral braces to the
center spar sections.
Lift the panels off the board when dry,
and trim and sand to shape. Do not cut the
ailerons loose yet. Join the two panels to
the center spars, using plenty of clamps
on the braces. Finish the bottom of the
center with the 1⁄16 sheet, and sand
everything smooth.
My model’s wing weighed 64 grams
at this stage.
Install all the aileron wire bushings
without glue. Cut the ailerons loose, and
shape the leading edge to a bevel.
Temporarily fit the ailerons on their
hinges. I recommend the small Klett
hinges from Carl Goldberg Models.
Slide the wire rods through the
bushings, and join in the center with a thin
brass tube. Fabricate and install the
plywood control horns and finish bending
Continued from page 17
Bristol Brownie
24 M ODEL AVIATION
the wire rods, leaving the ends so the
ailerons can be removed.
When everything lines up, solder the
brass tube in the center to both rods. Slide
the rod back and forth, and note the free
action without play. When satisfied, put a
small drop of glue on each bushing and
remove the ailerons for covering.
Bend up the 1⁄16-inch-diameter wire
landing gear assembly, and bind and solder
where shown. Cut the fairings from 3⁄16
balsa stock, and shape to a streamlined
section. Slot to fit over the wire, but do not
install until covered.
Wheels: These are made from a sandwich
of 1⁄16 balsa discs with a brass-tube bushing
for the axle. Work with a sanding block to
achieve the conical shape on the outside
surface. Wrap sandpaper around a dowel,
and sand a round groove for the tires.
I made my tires from vacuum tubing
bought at an auto-parts store. CyA glue does a
fine job of attaching the tubing. (Attach tires
after covering hubs.) Cut the tail skid from 1⁄8
plywood and sand smooth. Stain if desired.
Covering: I am poorly equipped to give
much advice on covering with plastic. I took
pains to bond the film completely to all the
wood surfaces, and I am very glad I did.
Since only one Brownie was built, there
is little choice if you want a scale color
scheme; however, this is your model and
you can use whatever colors suit you. The
plan sheet has the references for the scale
color-and-markings.
I used a trim film from Sig Manufacturing
for the letters, and I highly recommend it. The
adhesive is slightly less aggressive, and you
can get a “second chance.”
Final Assembly: Fit the wing in the
opening and seat the mounting screws. The
tail surfaces are aligned in relation to the
wing, so take care, measure twice, and glue
once. I used flexible plastic hinges cut 1⁄4-
inch wide on the tail surfaces.
Mount the landing gear and drive motor.
Fit the cowling, trimming clearance as needed
around the gear drive. I used clear plastic tape
to hold the cowl on my Brownie. Install the
plywood horns on the tail surfaces, and make
an elevator pushrod from a 3⁄16 square balsa
stick with 1⁄32-inch-diameter wire ends.
I used servo-mounting tape (Great
Planes brand) to mount my servos, and I am
very pleased with the result. Make and
install the wire link from the aileron servo
arm, double-checking for smooth operation
and neutral settings.
Bend the elevator pushrod to length and
install with “Z” bends. I made my rudder
pull-pull lines from SpiderWire™ fishing
line, and used short lengths of aluminum
tubing crimped at the ends to secure it. Check
all controls for smooth and free operation.
I made a few flights with my Brownie
before installing the scale motor and pilot
(chicken, I guess). The motor battery should be
used to balance Brownie where shown on the
plans. Find a way to secure your Brownie in a
clear area outdoors, and do a thorough range
check with the motor running at all speeds.
Flying: Because of the close spacing
between the center of gravity and the axle,
Brownie needs full up-elevator at the start
of the takeoff roll. Once the speed builds
slightly, relax the stick to neutral.
Meanwhile, the rudder will be needed if
there is any crosswind blowing.
When the speed looks reasonable, apply a
little back-stick and Brownie will lift smoothly
when ready. Keep the initial climb smooth and
shallow while you gain a little altitude.
You should be at 100 feet very quickly,
26 M ODEL AVIATION
where you can throttle back to half power
and start getting acquainted.
The roll and pitch response is smooth and
crisp—comfortable. Put the nose in a shallow
dive and go to full power, and observe how
fast Brownie accelerates! Still looking good?
Plan on a long, flat glide when you set up for
touchdown; Brownie is quite clean.
You can touch down three-point or mains
first; either technique works fine. If you are
landing in grass, a three-point flare will help
prevent a nose-over. Take the model home
and put on the finishing touches.
The scale motor is made from bits of
balsa. I spun the cylinders in a drill, and
used a Dremel® with a parting wheel to cut
the fins. It went quickly and looks good.
Use flat model enamels to paint the parts
before final assembly. Cut the windshield
from a section of a two-liter drink bottle,
where the bottle tapers near the top. Attach
the windshield with a strip of trim film.
I am not the world’s best sculptor, but I
persevered and I have a light balsa pilot. Do
what you can, but please don’t glue one of
those heavy plastic dolls on Brownie. This
is not a payload event!
I hope you can have fun with Brownie. If
you have any questions, I will be glad to
try to help. MA
Dave Robelen
Route #4 Box 369
Farmville VA 23901
[email protected]
