FIRST FLOWN IN 1931, the de Havilland
Tiger Moth, a dual-cockpit, dual-controlled
biplane, was designed to be a primary trainer.
It went on to become one of the most widely
used aircraft by flying clubs and auxiliary
squadrons around the world.
The Tiger Moth was actually a higherpowered,
upgraded version of the Gipsy Moth.
The Tiger Moth played a significant role in the
British Commonwealth Air Training Plan, and
large numbers were built in Canada, equipped
with floats, skis, and many with sliding
canopies for cold-weather operation.
Not only was the Tiger Moth an excellent
trainer, but it also served well for coastal
submarine patrols at the beginning of World
War II. Many are still flown by private owners
today.
Many years ago, a friend who owned a
Tiger Moth told me that it was almost the
perfect trainer. It was relatively easy to fly, and
although it would “amplify” the student’s
mistakes, it wouldn’t “hang him out to dry.”
My dad told me the same thing regarding
the Piper J-3 Cub. Having built and flown
models of both the J-3 and the Tiger Moth in
several sizes, I affectionately look at the Tiger
Moth as the “Cub of biplanes.”
The full-scale Tiger Moth had a wingspan
of 28 feet, 4 inches; a length of 23 feet, 11
inches; and was powered by the 130-
horsepower Gipsy Major engine with a twoblade
wooden propeller. Its top speed was 104
mph, it cruised at 90 mph, and it stalled at 43
mph.
The rate of climb was 673 feet per minute,
and the Tiger Moth had a service ceiling of
13,600 feet. Empty weight was 1,115 pounds,
and gross weight was 1,825 pounds.
An oversized
RC park flyer
of the classic
trainer
FIRST FLOWN IN 1931, the de Havilland
Tiger Moth, a dual-cockpit, dual-controlled
biplane, was designed to be a primary trainer.
It went on to become one of the most widely
used aircraft by flying clubs and auxiliary
squadrons around the world.
The Tiger Moth was actually a higherpowered,
upgraded version of the Gipsy Moth.
The Tiger Moth played a significant role in the
British Commonwealth Air Training Plan, and
large numbers were built in Canada, equipped
with floats, skis, and many with sliding
canopies for cold-weather operation.
Not only was the Tiger Moth an excellent
trainer, but it also served well for coastal
submarine patrols at the beginning of World
War II. Many are still flown by private owners
today.
Many years ago, a friend who owned a
Tiger Moth told me that it was almost the
perfect trainer. It was relatively easy to fly, and
although it would “amplify” the student’s
mistakes, it wouldn’t “hang him out to dry.”
My dad told me the same thing regarding
the Piper J-3 Cub. Having built and flown
models of both the J-3 and the Tiger Moth in
several sizes, I affectionately look at the Tiger
Moth as the “Cub of biplanes.”
The full-scale Tiger Moth had a wingspan
of 28 feet, 4 inches; a length of 23 feet, 11
inches; and was powered by the 130-
horsepower Gipsy Major engine with a twoblade
wooden propeller. Its top speed was 104
framed with formers and stringers, and the tail
group features bowed outlines, to keep the
weight down. Long-tailed, short-nosed
models can require a good bit of nose weight
to balance if the builder doesn’t take care to
ensure that the aft end stays light.
The wings feature egg-crate-style
construction, to assure ease of assembly, and
are plugged into the fuselage and top wing
center-section in pairs, to accelerate breakdown
and reassembly for easy transport. To
ease the scratch-building process, a laser-cut
parts package and vacuum-formed plastic
cowl and oil tank have been developed for the
design.
To blend old-technology airframe design
with modern electronics, the Tiger Moth is set
up for the readily available E-flite Park 400
outrunner brushless power system and mini
RC equipment. Therefore, it will be easy to
build and set up and will fly excellently.
CONSTRUCTION
Begin by bowing the rudder, elevator, and
wingtip outlines. Bowing patterns are made
from 3/16-inch-thick artist’s foam board using
the templates provided. Rudder and elevator
outlines are formed using two laminations of
1/16 x 1/8 balsa. The wingtips are formed using
two laminations of 1/16 x 3/16 balsa.
The secret to successfully bowing the
outlines is sufficiently soaking medium-firm
balsa in water, to soften it. Pull the bows
I designed the model to approximately 1:8
scale and use four-channel RC and brushless
power. The idea was to build a large park flyer
that was slow enough to fly in smaller venues
but big enough to handle less-than-perfect
weather conditions. If slow, scale flying is
“your bag,” the Tiger Moth might be for you!
The model is easy to transport. The wings
are removable in pairs, in case the model
needs to be disassembled. But it will
reassemble at the field in less than a minute.
The Tiger Moth structure looks more like
an FF model than a typical RC design but is
not a difficult build. The fuselage is stick
around the forms and glue them with either white glue or medium CA.
To speed up the forming process, the parts can be dried while
still on the forms. Place them in the microwave oven on high for
12-14 seconds.
For the dedicated scratch builder, provided pattern sheets can be
transferred directly to 1/16 and 1/8 x 4 x 24-inch balsa sheets, to make
your own print wood to simplify the parts-cutting process. The other
alternative is to use the laser-cut-parts pack.
Framing the Tail Section: The elevator and rudder are built directly
over the plans. Pin the shaped parts in place and add the 1/8 square
balsa spars, followed by preformed outlines. Add the ribs, using 1/16 x
1/8 balsa.
When dry, remove the assemblies from the board and cut the
surfaces apart. Sand the borders to a radius and slot for hinges. The
hinges are made using the supplied pattern. Don’t glue the hinges until
after you cover the parts.
Framing the Wings: The top wing’s construction begins with the
center-section. Join the upper and lower sheets from parts WCST and
WCSB. Ribs and spars are assembled directly on the bottom sheeting.
Glue the 3/16-inch-OD and 5/32-inch-OD x 3.3-inch-long aluminum
receiver tubes in place, leaving roughly 1/32 inch protruding on both
sides. Sand the contour into the LE and TE, and glue the top sheeting
in place.
Remove the center-section from the board
and sand to final shape. Add corrugation using
your favorite method or the available plastic
detail parts.
The top wing panels are assembled over
the plans. Pin the 1/4 x 1/2 balsa LE and 1/16 x
1/4 balsa TE in place, followed by A3 and A5.
Adhere main spars A1T and A8 in place on
A5, and glue ribs R2, R3, and R4 in place.
Use the rib angle gauge to set R1’s proper
angle and glue it in place. Trim A8A and glue
it in place, followed by the 5/32-inch-OD front
and 1/8-inch-OD rear by 3.8-inch-long
aluminum joiner tubes.
Trim the wingtip bows at the LE and TE.
Sand the bottom of the bow to flow into the
TE from the main spars and adhere in place.
Fit and glue the 1/16 square balsa top spars in
place. When dry, remove the wings from the
board and sand to shape.
Begin the bottom wing construction by
gluing the A2A aileron spar doublers in place
on A2 and the R3A rib doublers in place on
R3. Pin the LE and TE and A4 in place over
the plans, followed by the spar assemblies.
Glue ribs R3, R6, R7, and R8 in place.
Align R5 using the rib angle gauge and glue it
in place, followed by the 5/32-inch-OD and 1/8 -
inch-OD x 3.8-inch-long aluminum joiner
tubes.
Trim the wingtip bows at the LE and TE.
Sand the bottom of the bow to flow into the
TE from the main spars and glue in place. Fit
and adhere the 1/16 square balsa top spars in
place.
Trim aileron servo-mount plate SM1 as
needed to fit the servo used. Glue it in place
flush with the bottom of R3 and A1B,
followed by support gussets SM2 and SM3.
The ailerons are built in place on the wing
assembly. Glue inboard rib AR1 to A9. Be
sure to get the angle set up correctly. Trim A9
to fit the tip bow, and adhere AR1 to the TE
and A9 to the tip. Glue A10 and the AR2 ribs
in place to complete the assembly. When dry,
remove it from the board and sand to shape.
Cut the aileron from the wing panel and
sand to shape. Cut the hinge slots into the
aileron spars 1/16 inch below the wing’s top
surface and angled downward at
approximately 30°.
The hinges are made using the provided
patterns and should be folded so that the
aileron will hold a neutral position when the
hinges are installed. Use the Aileron Servo
Detail drawing for reference.
Now that the top and bottom wing
assemblies are finished, plug the top wing
panels into the center-section to check the fit.
Since there are no mechanical devices
attaching the wing panels into the centersection,
an easy way to snug up the connection
is to use a pair of needle-nose pliers to gently
squeeze the front mounting tubes on the outer
panel just enough to cause a slight interference
when the wings are plugged in.
The same procedure will be used to retain
the bottom wings in the fuselage. I know what
you might be thinking, but don’t worry! A
slight amount of interference is all it takes to
keep the wings in position
August 2009 37
Fuselage: Pin B1 in place over the Main
Fuselage Frame assembly drawing. Build the
frame using the wood sizes shown. When dry,
remove the first frame assembly from the
board and build the second frame.
The fuselage frames are joined directly
over the top/bottom view of the fuselage
framing drawing. Cut the rear landing gearmount
beam from 1/8 x 1/4 balsa, and gouge a
1/16-inch-diameter slot down its length. Pin the
landing gear mount and the 1/8 square balsa
crosspiece at the rear of B1.
Score B1 on the outside edge, and “crack”
the side frames to angle the sides into the tail
post. Adhere the side frames in place on the
mount beam and crosspiece. Use machinist’s
squares or triangles to ensure that the frames
are perpendicular to the building board,
followed by top formers 1, 2, 3, and 4 and the
1/4 square balsa cabane-mount beams.
Pull the tail posts together and glue, using
the squares to ensure proper alignment,
followed by formers 5, 6, 7, 8, and 9 and the
1/16 x 1/8 balsa crosspieces.
The firewall is laminated from FW, FWA,
and FWB. Notice the orientation of the slots
for the motor mount to accommodate the
right-hand offset. Use the Firewall Assembly
Detail drawing for reference.
Build the motor-mount assembly and glue
it in place on the firewall. Adhere the firewall
assembly in place on the fuselage frame using
a square to ensure proper alignment.
When dry, remove the frame from the
board and glue the 1/16 x 1/8 front diagonal
braces and the 3/16-inch-OD front and 5/32-inch-
OD x 3.3-inch rear aluminum lower wingmounting
tubes in place. Cut the front landing
gear-mount beam from 1/8 x 1/4 balsa, gouge a
.047-inch-diameter slot down its length, and
glue in place.
Fit and glue all 3/32 square balsa stringers in
place on the fuselage top and sides, the 1/8
square balsa hatch rails inside the front bottom
longeron between the landing gear mount
beams, and the B4 tail-skid support blocks.
Landing Gear and Cabane Struts: Bend the
cabane struts from .046-inch-diameter wire
and solder them together over the plans. Be
sure to make one left- and one right-hand
assembly. Drill the cabane-mount beams using
a #56 bit. Fit the cabanes into the fuselage
assembly.
Main landing gear struts are bent from
.062-inch- and .046-inch-diameter wire. Tape
the front and rear struts in place on the
fuselage frame, and solder together using the
Landing Gear Assembly drawing for
reference.
Remove the cabane struts and landing gear
from the fuselage frame. Add the balsa
fairings, sand to shape, and seal with two coats
of water-based polyurethane varnish or dope.
Lash the landing gear to the mount beams with
Kevlar thread, and glue. Bend the tail skid
from .046-inch-diameter wire, lash to the tail
post with Kevlar thread, and glue.
The last step in framing is to make the
battery hatch using .010-inch-thick styrene
plastic and 1/8 square balsa.
Radio and Motor Installation: Glue the 1/8
square balsa servo-rail mounts and 1/8 x 1/4
balsa servo rails in place in the rear cockpit.
Space the rails to accommodate the servos
used, and mount the servos on the rails.
The rudder and elevator pushrods are made
from Sullivan Products pushrod tubes and
.032-inch-diameter wire pushrods. Glue the
B2 and B3 pushrod-tube rear supports in place
on their respective sides on the aft fuselage.
Adhere the pushrod tubes in place at B2
and B3, and glue the provided pushrod
supports to secure the tubes at the front, rear,
and at least two places in between. Make a Z
bend or use a micro easy connector at the front
end, and secure it to the servo arm. Cut the
wire with 2 inches of excess at the rear, where
the aft Z bends will be made during final
assembly.
For those of us who prefer a pull-pull
system for the rudder, a diagram is provided
for setting it up using a cable and a toothpick
for the control horn. If you do use the pull-pull
system, omit B2 and mount the rudder servo
on the fuselage centerline.
Then run the cables in and mark on the
plans the exact location where they exit the
fuselage, for future reference. The exit points
will be used during final assembly, when
running the cables out through the cover.
The aileron servos are mounted in the
wings using double-stick tape or silicone
caulk. Extend the leads to exit the wing root
with 2 inches of slack. Make sure the servo
arms are centered before you permanently
mount the servos.
Mount the motor on the firewall and
connect the ESC. Test the system without the
propeller for proper operation and make
necessary changes now, while the components
are still easily accessible.
Glue the receiver mounting tray in place
between formers 2 and 3, under the front
cockpit, and mount the battery tray as shown,
behind the firewall. Mount the battery and
ESC to their respective trays using Velcro.
Laminate, shape, and glue the cowl
mounting tabs, and adhere them in place on
the firewall using the cowl to locate them
properly. Trim the cowl and fasten it in place
with #2 sheet-metal screws.
Covering: Before you begin, sand the entire
structure to remove any remaining bumps or
boo-boos. Clean the entire structure with a
damp paper towel.
The model can be covered with light
silkspan and dope or light Mylar iron-on
covering such as Nelson LiteFILM from
Nelson Hobby Direct, which is also available
under the name Coverite Microlite and
Solarfilm. I don’t recommend using materials
such as MonoKote or UltraCote; they are too
heavy, and their extreme shrinking qualities
will damage the Moth’s light structure.
For best results with whatever material
you choose, follow the manufacturer’s
recommendations for application.
Once all covering is in place, prepare the
plastic cowl and oil tank for painting. I
airbrushed the plastic parts with Model Master
Enamels and brushed the wing center-section,
landing gear, and cabane struts with two-coats
of Model Master Acryl.
Callie Graphics custom-made the graphics
on the prototype. Now is a good time to
shape, seal, and paint or stain the interplane
struts.
Final Assembly: Glue the aileron, elevator,
and rudder hinges in place using Pacer
Canopy 560 glue from Frank Tiano
Enterprises. I don’t use thin CA, because it
leaves the hinge too stiff.
Plug the bottom wing into the fuselage, and
use it as a reference to align and glue in place
the horizontal and vertical stabilizers. Pay
attention here, so that the elevator control-horn
notch doesn’t end up on the wrong side.
Set up the elevator (rudder) and aileron
pushrods by centering the servo arms. With the
control surface in its neutral position and the
control horn dry-fitted in the slot, mark and Zbend
the pushrods. Fit the control horn over
the Z bend and glue it in place on its respective
control surface.
The aileron pushrods are also set up using a
.032-inch-diameter-wire pushrod with a Z
bend on each end. A V bend can be added to
the pushrods if so desired, but later adjustment
won’t be necessary if care is taken.
If the rudder is connected using the pullpull
system, mark the location where the
cables will exit the fuselage. Reinforce the
covering there with a 1/2-inch-square piece of
hinge tape, and cut a 1/8-inch slit through
which the cable can come. Pull the cables
through the fuselage and tie off to the control
horn. Secure with a drop of thin CA.
To set up the top wing, make the wingalignment
fixture and two wing-rigging
fixtures from 3/16-inch foam artist’s board
using the provided templates. Pin the
alignment fixture in place on the fuselage
centerline, and fit the top wing assembly onto
the cabanes.
Use the interplane struts and wing-rigging
fixtures to set up the lateral alignment, and
glue the center-section in place atop the
cabanes with five-minute epoxy. A drop of
thin CA at each interplane-strut attach point
will secure the wings nicely.
The wing rigging is done using 40-poundtest
Kevlar fishing line. The rigging extends
from the top rear wing-mount tube to the
bottom of each interplane strut, from the front
bottom wing-mount tube to the top of each
interplane strut, and making an “X” between
the interplane struts.
By starting and ending at the top rear
mounting tube, each side can be completed
with a piece of string that is approximately 84
inches long. Where the string comes around
the front lower wing-mount tube, wrap it
around the tube once. Then the wings can be
slid out roughly 1 inch, and the string can be
secured with a drop of thin CA.
With the rigging secured in place, use
Pacer Canopy glue to adhere the .080-inchdiameter
x 37/8-inch styrene plastic rigging
support “javelins” in place at the crossover
junction.
Now it’s a matter of adding the last of the
details, such as the stabilizer support struts,
windshields, wheels, cowl, and oil tank. To
retain the wheels, I drilled Nelson T-pin
clamps to 1/16-inch-ID tubing, slipped them
over the axles on both sides of the wheel, and
secured them with a small drop of thin CA.
Make the stall slats from thin aluminum
sheet. I used printer’s litho plate. The slats are
optional, but add them if you like a wellbehaved
airplane that lands at walking speed;
they do make a difference.
With the battery mounted in the model, set
up the CG 21/4 inches from the LE at the
center-section. Set the control throws as shown
on the plans.
Double-check to make sure that the
propeller will turn and the controls move in the
right direction. With that, the Tiger Moth is
ready to fly!
Flying: We’re at the point we’ve been
anticipating: maiden-flight day. Before you fly
your Tiger Moth, mount a freshly charged
battery and recheck the CG, the control
throws, and direction, and that the propeller is
turning the right way. If all of that looks good,
it’s time to fly.
For the first trim flights, pick a nice, calm
day. There’s nothing worse than trying to trim
a new model in choppy air.
To take off, point the Moth into the breeze,
hold slight up-elevator, and advance the
throttle to nearly two-thirds power. Use the
rudder to track the model straight down the
runway. If it doesn’t lift off on its own, a touch
more up-elevator will be all you need.
Keep the climb shallow and use rudder and
ailerons together to make turns. The model
will turn okay on rudder or ailerons alone but
is slow to react.
Climb the Moth to a safe altitude and trim
it for straight and level flight at just more than
half throttle. By now, you’ve probably noticed
that it is a slow, smooth, and docile flyer. Try a
few turns to get a feel for the necessary
rudder/aileron coordination.
Try a stall for fun. When you’re nearing stall
speed carrying a bit of power, use the rudder for
directional control and see how slow you can
make the airplane fly. You’ll be amazed by how
slowly it will fly and how controllable it will be
throughout its speed range.
To land, set up the approach carrying a bit
of power. Keep the nose down a bit, or the
model will get so slow that it will be at the
mercy of any moving air. Fly it down to
almost a foot of altitude and raise the nose
slightly to bleed off the last of the speed. Once
in ground effect, the airplane will float down
to a nice three-point landing as the power is
reduced.
For some serious fun, try a few touch-ngos.
The more you fly the Tiger Moth, the
more you will see that it has no vices. And for
slow, relaxing park flying, I think you’ll find it
hard to beat. MA
Pat Tritle
[email protected]
Sources:
Laser-cut parts pack, vacuum-formed plastic
parts:
Pat’s Custom Models
(505) 296-4511
[email protected]
Callie Graphics
(505) 293-2922
[email protected]
E-flite
(800) 338-4639
www.horizonhobby.com
Sullivan Products
(410) 732-3500
www.sullivanproducts.com
Nelson Hobby Direct
(877) 263-5766
www.nelsonhobby.com
Frank Tiano Enterprises
(863) 607-6611
www.franktiano.com
Model Master
(800) 962-6654
www.testors.com
