LTR-14 Turner Special - 2009/12

24 MODEL AVIATION
At roughly 1/6 scale, the LTR-14 is close in size to most
40-size models. The wings plug into the fuselage and
include working flaps.
Do you think all that racers can do
is go fast and turn left? Not this
one. Its large fuselage also makes
extended knife-edge flight possible.
12sig1.QXD_00MSTRPG.QXD 10/23/09 9:27 AM Page 24
IN JANUARY 2007, the E Zone and
Manzano Laser Works sponsored an electric-powered,
scale model “build-off.” This contest pitted designers around the
world against each other, to design, construct, and fly a scale model
in six months.
When the balsa dust settled, more than 20 new airplanes were flying (and
several others were still on the board). Online viewers had voted my LTR-14 Turner
Special the winner of the pro-civilian category.
Although Roscoe Turner might not have been the best pilot of his time, he was
the only one to win the Thompson Trophy race three times. Two of those victories
December 2009 25
Designed around
electric power, this
Thompson Trophywinning
replica scores
The Turner is well
behaved in the air
and has no bad stall
tendencies. It will
perform any basic
aerobatic maneuver.
The layout of the scale dashboard is included on the plans. The clear canopy and graphics
package are available from T&J Models.
Photos by the author
by Jim Young
12sig1.QXD_00MSTRPG.QXD 10/23/09 9:28 AM Page 25
26 MODEL AVIATION
17
Top: The stabilizer features built-up
construction under 1/32 balsa sheeting.
Elevators are left as open structures. A
laser-cut parts package is available from
the author.
Right: The amount of fun you have building
is your choice. Laser-cut parts are a work
of art, but a builder can make his or her
own from plans templates.
The fuselage starts with building the
internal crutch from spruce that extends
from the forward plywood frame.
Formers are threaded onto the completed
crutch assembly, and the frame begins to
lift off the board so it can rest back down
onto 4-inch-tall fixture blocks.
The fuselage rear is almost entirely balsa
stringers. Install the pushrods before
completely running the stringers.
A few stringers support the balsa
sheeting. Extending forward, they are
trimmed so that the joining sheeting fits
flush to the stringers.
The landing gear uses conventional music
wire and nylon mounting straps. The
bottom of the fuselage is finished off with
1/16 balsa sheeting.
Above: The fin is fairly wide at the base and
requires several ribs. The stabilizer and fin
outline is laminated from strips of 1/16 balsa.
Plywood plates on each side of the crutch
capture the torque rod ends of the landing
gear. Spruce crossmembers add support.
12sig1.QXD_00MSTRPG.QXD 10/23/09 9:29 AM Page 26
December 2009 27
A large hatch built into the fuselage’s top
allows easy access to the battery and radio. A
basswood rail provides a dent-resistant edge
to the hatch.
Graduated layers of balsa help shape the
removable cowl. It is built up with a few
formers and sheet balsa.
The intake scoops are a combination of laminated
material and carved balsa block. Any aluminum-colored
iron-on covering should give a reasonably scale
appearance.
The completed
airframe is light
and strong. The
wing panels
have a
f o a m
c o r e ,
which are available from the
author. The wheel pants are cut
and carved from balsa blocks, and
standard hardware is used to
mount them to the
landing gear.
Scale details such as the oil cooler scoops set the LTR-14
off at the field. In this case, the scoops are also functional
ram-air intakes for cooling the power system.
The author used Hitec HS-65 servos on the tail
surfaces, HS-55s for the ailerons, and a standard-size
servo on the flaps. A Hacker A30-10XL motor with a
3S battery turns an APC 14 x 7E propeller.
Add completed tail feathers to the
fuselage once the wing panels have been
mounted. Some 1/16 sheeting will close
and support the horizontal stabilizer.
Type: RC semiscale electric
Skill level: Intermediate builder and pilot
Wingspan: 51.4 inches
Wing area: 480 square inches
Length: 45.3 inches
Weight: 65 ounces
Wing loading: 20 ounces/square foot
Motor: 400-450 watts; 3S 5000 mAh Li-Poly battery
Radio: Six channels, five servos
Construction: Primarily
balsa, foam-core wing
Covering/finish: Heat-shrink
film
Other: 45-amp ESC,
14 x 7 APC propeller,
5-amp BEC
12sig1.QXD_00MSTRPG.QXD 10/23/09 9:35 AM Page 27
were in the Turner Special.
In 1936, feeling that his Wedell-
Williams racer could not get any faster,
Roscoe set out to build a new, all-out racing
machine. He entered a contract with Larry
Brown (of Miss Los Angeles fame) to build
a racer around the new twin-row Wasp
engine.
After almost two years and several
modifications, Matty Laird finally
completed the aircraft. He had it registered
as the LTR-14 (Laird Turner Racer), much
to Roscoe’s disappointment.
However, after sorting out the bugs,
Roscoe went on to win the 1938 and 1939
Thompson Trophy races piloting his
“Turner Special.”
CONSTRUCTION
This project requires modeling
experience and skill. To ease construction, I
have made a short kit of laser-cut parts,
foam wing cores, and vacuum-formed
canopy available from me. If you take on
fabricating those parts yourself, cutting your
own “kit” now will speed construction.
Tail Feathers: The stabilizer/elevator and
fin/rudder outlines are laminated from four
layers of 1/16 balsa. You can either cut a
cardboard template or use several pins
through the plans to form the outlines. I
used aliphatic glue and wet the strips, to
make them easier to bend.
Pin the stabilizer/elevator outline over
the plans, and cut and glue in place the
internal structure. The stabilizer is covered
top and bottom with 1/32 balsa sheeting,
while the elevators are left as open
structures.
Laminate the tail filler piece from 1/16
balsa. Sand a slot in the front of this piece,
to clear the elevator joiner wire.
Cut a 1/4-inch square balsa stick for the
rudder LE, and glue the rudder ribs to it. Fit
the laminated rudder outline to the ribs, and
glue it in place. Add balsa blocks to support
Robart hinge points.
Wrap the rudder LE with 1/16 balsa or
two layers of 1/32 balsa. You will need to
wet the balsa first, and pin or tape it in place
while it dries before gluing it in place. Add
balsa capstrips to the ribs. The rudder is
wide enough at the base to accommodate
pull-pull control, or install a control linkage
of your choice.
Glue fin ribs F1 through F7 to the 1/4
balsa fin post F8 and the laminated fin
outline. Temporarily hinge the rudder, and
cut some 1/4 balsa triangle stock to fit on
each side of the rudder to hide the hinge
line. Set these aside, to be glued in when the
fin is installed on the fuselage.
Wings: The wing has a foam core and is
sheeted with 1/16 balsa. A laminated
plywood wing joiner is built into each wing
panel. Laminate the two wing joiners from
three layers of 1/16 plywood. Sand the top
and bottom edges smooth.
Prepare the cores for sheeting by
beveling the root end 3°. Cut the cores to
accept the wing joiners. Glue the wing
joiner, root ribs, and subribs to the cores.
Glue the wingtip core to the root assembly.
Cut slots for the aileron extensions and
lay them in place. Protect them at the root
rib with heat-shrink tubing or electrical tape.
Sheet the wing with 1/16 balsa, using
your favorite method. I recommend epoxy
or Gorilla Glue and the vacuum-bag
technique.
Cut the ailerons and flaps free from the
wing. Face the wing LE and TE with 1/4
balsa. Similarly, face the LE of the ailerons
and flaps. True the ends of the ailerons and
the tip end of the flaps, and face them with
1/16 balsa.
The root ends of the flaps have a pocket
built into them, to receive the control rod.
Remove approximately 1/2 of the foam core
from the root end of the flap.
The inside of the bottom skin is
reinforced with 1/64 plywood. Use a 1/16
shim, and fill the remaining space above it
with balsa block. Sand a bevel (roughly 1/8
inch) along the lower LE of the flaps. Hinge
the flaps to the wing along this line.
Cut balsa block for the wingtips, and
glue them in place. I reinforced the TE of
the wingtips by cutting a slot with a razor
saw and gluing in a small piece of 1/64
plywood. Sand everything away that doesn’t
look like a wingtip. Cut an opening for the
aileron servos, and make hatches from 1/16
plywood.
Fuselage: The fuselage is framed up over an
internal crutch; 1/8 x 1/4 spruce longerons are
glued to the crutch sides. Fit the radio tray
CR1s and spar box pieces SB1s and SB2 to
the sides. Position the crutch assembly over
the plans and pin it in place before gluing.
Cut the longerons to length, taper the ends,
and glue them together. Cut and glue the balsa
crossbraces and diagonal braces between the
longerons.
Laminate the plywood landing gear
mounts and two 1/8 x 1/4 spruce sticks together.
Glue F2A and F3A in place between the
crutch sides. Laminate the 1/16 plywood torque
blocks together and epoxy them in place on
the inside of the crutch sides. Epoxy the
landing gear mount in place.
Remove the assembly from the board.
Glue the remaining crutch pieces in place,
using the fuselage formers to align them. Glue
the fuselage formers and motor mount in
place. Add triangle-stock reinforcements to all
motor-mount joints.
Bend the flap torque rods from 1/16-inchdiameter
music wire, using inner Nyrods for a
bearing. Insert the torque rods into the holes in
the crutch sides, and glue the wing-root plates
CR4s in place. Glue the torque-rod sleeve in
place, and brace them near the slots in the
radio tray.
Cut three fixture blocks from 4-inch-wide,
1/2 balsa, and fixture the fuselage over the
plans. Bend the landing gear from 5/32-inchdiameter
music wire and secure in place with
a pair of nylon straps and screws.
Glue the balsa diagonal braces from F7 to
F10. Start installing the 3/32 x 3/16 balsa rear
stringers. Each stringer is notched to half its
depth at F7 and F11 and extends at least 1
inch past these formers.
Glue three 1/4 square balsa stringers into
the notches from F2 to F7. Add scrap balsa to
the inside edges of the CR4s, to aid in gluing
the fuselage sheeting.
The fuselage has a gentle compound
curve, but you should attain good results with
four 3-inch-wide pieces of 1/16 balsa. The
fuselage should now be stable enough to be
removed from the fixtures.
Finish installing the upper rear stringers.
The edges of the cockpit are framed with
scrap balsa.
A large access hatch is built into the top of
the fuselage. Cut four pieces of 1/16 basswood
for the hatch edges; they should be oversized
in width. Glue the bottom piece and F6 into
the fuselage structure.
Use waxed paper and set the top piece in
place, and glue the hatch formers in place.
Leave a 1/32-inch gap between the hatch end
formers and the fuselage formers.
Sheet the hatch and fuselage with 1/16
balsa. The sheeting should be beveled to fit
tight to the basswood pieces. As you install
the sheeting, cut it between F2A and F2B and
F6 and F6A. Cut the hatch free from the
fuselage.
Face the front and rear end of the hatch
and hatch opening with 1/64 plywood. Put
the hatch back in place, and sand the
basswood and plywood to match the
sheeting. Cut the sheeting aft of F7 to shape
for the cockpit, and trim the canopy to fit.
Laminate the 1/4 balsa SC1 through SC7.
Glue the subcowl to the front of F2. Glue the
F1 pieces in place. Sand the subcowl to shape.
Position the cowl formers on the front of
the fuselage crutch. The cowl is held in place
with two screws that go through C1, into the
firewall.
Cut 1/4 square balsa stringers and glue
them in place around the formers. Sheet the
cowl with 1/16 balsa. The sheeting extends 1/4
inch behind C4, and a strip of 1/64 plywood
reinforces it. The front of the cowl is
laminated from seven rings of 1/4 balsa and
sanded to shape.
Laminate two wing-joiner wedges from
three layers of 1/16 plywood. With the wing
joiner protected with waxed paper, slide one
wing into place and push a wedge in from the
opposite side. The wedges hold the wing
joiner against the bottom of the spar box and
distribute the flight loads to the fuselage
crutch.
Make adjustments, and glue the wedge to
the inside top of the spar box. Repeat for the
other wing and wedge.
Slide the wings in place, and check the fit
to the CR4s; use them to line up the stabilizer
before gluing it in place. Glue the top of F11
to the stabilizer.
Adhere the tail-filler piece in place. Glue
the fin assembly in place. Temporarily hinge
the rudder, and use balsa to fill the gap
between it and the tail-filler piece. Install the
rudder control before sheeting the sides of the
The bottom rear of the fuselage is sheeted
with 1/16 balsa. Glue F12 in place, and adhere
the 1/4 square spruce tail skid to it. Add the 1/4
balsa skids, and reinforce them with 1/64
plywood on each side.
The landing gear is finished with balsa
filler sandwiched between 1/16 balsa sheeting.
Sand the landing gear to an airfoil shape. Use
balsa or filler to create the fillets around the
landing gear. The fillet should be glued only
to the fuselage—not to the landing gear—so
it can flex.
The wheel pants are laminated and carved
from balsa. The 1/16 plywood plates provide a
mounting point for wheel pant hardware.
Final Assembly: Fit the wings to the
fuselage, and use a pin or machine screw
through the hole in the spar box and spars to
secure them in place. Use either balsa
triangle stock or your favorite filler to create
the small wing fillet.
The original LTR-14 was painted silver,
and most of the iron-on coverings offer a
close match. The fuselage rear is quite curvy,
so expect to use three or four pieces of
covering around it to get all the wrinkles out.
Self-adhesive vinyl graphics are available
from Callie Graphics. The Turner Special
had several sponsors during its racing career
and appeared as the “Pesco Special” and
“Ring Free Meteor.”
I have created the markings for the “Miss
Champion,” and the BMP files are available
on my Web site—T&J Models—for
download. I printed the images on waterslide
decal sheets.
It has been said that scale models are
never finished; you just stop working on
them. So how far you go with the cooling
scoops, cockpit, pilot, and engine detail is up
to you. When painting the pilot, you might
want to keep in mind that I’ve seen color film
of Roscoe Turner wearing a white leather
helmet.
Complete your radio installation at this
time. I use Hitec HS-55 servos for the
ailerons, HS-65s for the rudder and elevator,
and DS821s for the flaps. All of the servos
are hooked up to a Spektrum AR7000
receiver.
The power system I am using is providing
great results. It consists of a Hacker A30-
10XL motor; 14 x 7E APC propeller;
Skyshark R/C 5000 mAh 3S Li-Poly battery;
FMA Direct BalancePro Discharge
Protection Module; and Castle Creations
Phoenix-45 ESC and Ultimate BEC. This
setup draws approximately 36 amps static
and provides more than enough power.
If you are using flaps, you will need to
use a separate receiver battery or a switching
BEC, because few ESCs can supply enough
current for five servos. The battery capacity
might seem like overkill, but the LTR-14 has
a short nose moment, so I did need the
weight up front to balance it.
Flying: The Turner Special is an honest
airplane. The rudder is extremely effective,
and takeoffs from grass fields are no
problem, even without a steerable tail wheel.
Taxiing on grass takes only a bit of
throttle management to move the tail around.
With the recommended power system, the
Turner Special can take off from a three-point
stance and climbs out with authority.
For landings, set up your normal approach
and keep on a bit of power until the model is
over the field. Let the airplane settle in and
keep adding up-elevator, and it will give you
a pretty three-wheel landing. Remember to
save some power, to taxi the LTR-14 back to
the pits.
People might think that all racers can do
is go fast and turn left. I’m happy to report
that this is not the case with the Turner
Special.
This model is well behaved in the air
and has no bad stall tendencies. It will
perform any basic aerobatic maneuver
(loop, stall turn, point roll, Cuban 8, etc.).
With the balance point directly on the joiner
tube, the LTR-14 flies inverted hands off.
The large fuselage also makes extended
knife-edge flight possible.
I’d like to thank Keith Shaw for letting
me pick his brain along the way and for his
talented thumbs for the initial flights. MA
Jim Young
[email protected]
Sources:
Manzano Laser Works
(505) 286-2640
www.manzanolaser.com
Callie Graphics
(505) 281-9310
www.callie-graphics.com
T&J Models
(505) 286-2640
www.tnjmodels.rchomepage.com
Hacker Brushless
(480) 726-7519
www.hackerbrushless.com
APC Propellers
(530) 661-0399
www.apcprop.com
Skyshark R/C Corporation
(928) 854-6100
www.skysharkrc.com
FMA Direct
(800) 343-2934
www.fmadirect.com
Castle Creations
(913) 390-6939
www.castlecreations.com
Spektrum RC
(800) 338-4639
www.spektrumrc.com
Hitec RCD
(858) 748-6948
www.hitecrcd.com
Jim Young
(810) 231-1684
9356 Wendover Ct.
Brighton MI 4811

24 MODEL AVIATION
At roughly 1/6 scale, the LTR-14 is close in size to most
40-size models. The wings plug into the fuselage and
include working flaps.
Do you think all that racers can do
is go fast and turn left? Not this
one. Its large fuselage also makes
extended knife-edge flight possible.
12sig1.QXD_00MSTRPG.QXD 10/23/09 9:27 AM Page 24
IN JANUARY 2007, the E Zone and
Manzano Laser Works sponsored an electric-powered,
scale model “build-off.” This contest pitted designers around the
world against each other, to design, construct, and fly a scale model
in six months.
When the balsa dust settled, more than 20 new airplanes were flying (and
several others were still on the board). Online viewers had voted my LTR-14 Turner
Special the winner of the pro-civilian category.
Although Roscoe Turner might not have been the best pilot of his time, he was
the only one to win the Thompson Trophy race three times. Two of those victories
December 2009 25
Designed around
electric power, this
Thompson Trophywinning
replica scores
The Turner is well
behaved in the air
and has no bad stall
tendencies. It will
perform any basic
aerobatic maneuver.
The layout of the scale dashboard is included on the plans. The clear canopy and graphics
package are available from T&J Models.
Photos by the author
by Jim Young
12sig1.QXD_00MSTRPG.QXD 10/23/09 9:28 AM Page 25
26 MODEL AVIATION
17
Top: The stabilizer features built-up
construction under 1/32 balsa sheeting.
Elevators are left as open structures. A
laser-cut parts package is available from
the author.
Right: The amount of fun you have building
is your choice. Laser-cut parts are a work
of art, but a builder can make his or her
own from plans templates.
The fuselage starts with building the
internal crutch from spruce that extends
from the forward plywood frame.
Formers are threaded onto the completed
crutch assembly, and the frame begins to
lift off the board so it can rest back down
onto 4-inch-tall fixture blocks.
The fuselage rear is almost entirely balsa
stringers. Install the pushrods before
completely running the stringers.
A few stringers support the balsa
sheeting. Extending forward, they are
trimmed so that the joining sheeting fits
flush to the stringers.
The landing gear uses conventional music
wire and nylon mounting straps. The
bottom of the fuselage is finished off with
1/16 balsa sheeting.
Above: The fin is fairly wide at the base and
requires several ribs. The stabilizer and fin
outline is laminated from strips of 1/16 balsa.
Plywood plates on each side of the crutch
capture the torque rod ends of the landing
gear. Spruce crossmembers add support.
12sig1.QXD_00MSTRPG.QXD 10/23/09 9:29 AM Page 26
December 2009 27
A large hatch built into the fuselage’s top
allows easy access to the battery and radio. A
basswood rail provides a dent-resistant edge
to the hatch.
Graduated layers of balsa help shape the
removable cowl. It is built up with a few
formers and sheet balsa.
The intake scoops are a combination of laminated
material and carved balsa block. Any aluminum-colored
iron-on covering should give a reasonably scale
appearance.
The completed
airframe is light
and strong. The
wing panels
have a
f o a m
c o r e ,
which are available from the
author. The wheel pants are cut
and carved from balsa blocks, and
standard hardware is used to
mount them to the
landing gear.
Scale details such as the oil cooler scoops set the LTR-14
off at the field. In this case, the scoops are also functional
ram-air intakes for cooling the power system.
The author used Hitec HS-65 servos on the tail
surfaces, HS-55s for the ailerons, and a standard-size
servo on the flaps. A Hacker A30-10XL motor with a
3S battery turns an APC 14 x 7E propeller.
Add completed tail feathers to the
fuselage once the wing panels have been
mounted. Some 1/16 sheeting will close
and support the horizontal stabilizer.
Type: RC semiscale electric
Skill level: Intermediate builder and pilot
Wingspan: 51.4 inches
Wing area: 480 square inches
Length: 45.3 inches
Weight: 65 ounces
Wing loading: 20 ounces/square foot
Motor: 400-450 watts; 3S 5000 mAh Li-Poly battery
Radio: Six channels, five servos
Construction: Primarily
balsa, foam-core wing
Covering/finish: Heat-shrink
film
Other: 45-amp ESC,
14 x 7 APC propeller,
5-amp BEC
12sig1.QXD_00MSTRPG.QXD 10/23/09 9:35 AM Page 27
were in the Turner Special.
In 1936, feeling that his Wedell-
Williams racer could not get any faster,
Roscoe set out to build a new, all-out racing
machine. He entered a contract with Larry
Brown (of Miss Los Angeles fame) to build
a racer around the new twin-row Wasp
engine.
After almost two years and several
modifications, Matty Laird finally
completed the aircraft. He had it registered
as the LTR-14 (Laird Turner Racer), much
to Roscoe’s disappointment.
However, after sorting out the bugs,
Roscoe went on to win the 1938 and 1939
Thompson Trophy races piloting his
“Turner Special.”
CONSTRUCTION
This project requires modeling
experience and skill. To ease construction, I
have made a short kit of laser-cut parts,
foam wing cores, and vacuum-formed
canopy available from me. If you take on
fabricating those parts yourself, cutting your
own “kit” now will speed construction.
Tail Feathers: The stabilizer/elevator and
fin/rudder outlines are laminated from four
layers of 1/16 balsa. You can either cut a
cardboard template or use several pins
through the plans to form the outlines. I
used aliphatic glue and wet the strips, to
make them easier to bend.
Pin the stabilizer/elevator outline over
the plans, and cut and glue in place the
internal structure. The stabilizer is covered
top and bottom with 1/32 balsa sheeting,
while the elevators are left as open
structures.
Laminate the tail filler piece from 1/16
balsa. Sand a slot in the front of this piece,
to clear the elevator joiner wire.
Cut a 1/4-inch square balsa stick for the
rudder LE, and glue the rudder ribs to it. Fit
the laminated rudder outline to the ribs, and
glue it in place. Add balsa blocks to support
Robart hinge points.
Wrap the rudder LE with 1/16 balsa or
two layers of 1/32 balsa. You will need to
wet the balsa first, and pin or tape it in place
while it dries before gluing it in place. Add
balsa capstrips to the ribs. The rudder is
wide enough at the base to accommodate
pull-pull control, or install a control linkage
of your choice.
Glue fin ribs F1 through F7 to the 1/4
balsa fin post F8 and the laminated fin
outline. Temporarily hinge the rudder, and
cut some 1/4 balsa triangle stock to fit on
each side of the rudder to hide the hinge
line. Set these aside, to be glued in when the
fin is installed on the fuselage.
Wings: The wing has a foam core and is
sheeted with 1/16 balsa. A laminated
plywood wing joiner is built into each wing
panel. Laminate the two wing joiners from
three layers of 1/16 plywood. Sand the top
and bottom edges smooth.
Prepare the cores for sheeting by
beveling the root end 3°. Cut the cores to
accept the wing joiners. Glue the wing
joiner, root ribs, and subribs to the cores.
Glue the wingtip core to the root assembly.
Cut slots for the aileron extensions and
lay them in place. Protect them at the root
rib with heat-shrink tubing or electrical tape.
Sheet the wing with 1/16 balsa, using
your favorite method. I recommend epoxy
or Gorilla Glue and the vacuum-bag
technique.
Cut the ailerons and flaps free from the
wing. Face the wing LE and TE with 1/4
balsa. Similarly, face the LE of the ailerons
and flaps. True the ends of the ailerons and
the tip end of the flaps, and face them with
1/16 balsa.
The root ends of the flaps have a pocket
built into them, to receive the control rod.
Remove approximately 1/2 of the foam core
from the root end of the flap.
The inside of the bottom skin is
reinforced with 1/64 plywood. Use a 1/16
shim, and fill the remaining space above it
with balsa block. Sand a bevel (roughly 1/8
inch) along the lower LE of the flaps. Hinge
the flaps to the wing along this line.
Cut balsa block for the wingtips, and
glue them in place. I reinforced the TE of
the wingtips by cutting a slot with a razor
saw and gluing in a small piece of 1/64
plywood. Sand everything away that doesn’t
look like a wingtip. Cut an opening for the
aileron servos, and make hatches from 1/16
plywood.
Fuselage: The fuselage is framed up over an
internal crutch; 1/8 x 1/4 spruce longerons are
glued to the crutch sides. Fit the radio tray
CR1s and spar box pieces SB1s and SB2 to
the sides. Position the crutch assembly over
the plans and pin it in place before gluing.
Cut the longerons to length, taper the ends,
and glue them together. Cut and glue the balsa
crossbraces and diagonal braces between the
longerons.
Laminate the plywood landing gear
mounts and two 1/8 x 1/4 spruce sticks together.
Glue F2A and F3A in place between the
crutch sides. Laminate the 1/16 plywood torque
blocks together and epoxy them in place on
the inside of the crutch sides. Epoxy the
landing gear mount in place.
Remove the assembly from the board.
Glue the remaining crutch pieces in place,
using the fuselage formers to align them. Glue
the fuselage formers and motor mount in
place. Add triangle-stock reinforcements to all
motor-mount joints.
Bend the flap torque rods from 1/16-inchdiameter
music wire, using inner Nyrods for a
bearing. Insert the torque rods into the holes in
the crutch sides, and glue the wing-root plates
CR4s in place. Glue the torque-rod sleeve in
place, and brace them near the slots in the
radio tray.
Cut three fixture blocks from 4-inch-wide,
1/2 balsa, and fixture the fuselage over the
plans. Bend the landing gear from 5/32-inchdiameter
music wire and secure in place with
a pair of nylon straps and screws.
Glue the balsa diagonal braces from F7 to
F10. Start installing the 3/32 x 3/16 balsa rear
stringers. Each stringer is notched to half its
depth at F7 and F11 and extends at least 1
inch past these formers.
Glue three 1/4 square balsa stringers into
the notches from F2 to F7. Add scrap balsa to
the inside edges of the CR4s, to aid in gluing
the fuselage sheeting.
The fuselage has a gentle compound
curve, but you should attain good results with
four 3-inch-wide pieces of 1/16 balsa. The
fuselage should now be stable enough to be
removed from the fixtures.
Finish installing the upper rear stringers.
The edges of the cockpit are framed with
scrap balsa.
A large access hatch is built into the top of
the fuselage. Cut four pieces of 1/16 basswood
for the hatch edges; they should be oversized
in width. Glue the bottom piece and F6 into
the fuselage structure.
Use waxed paper and set the top piece in
place, and glue the hatch formers in place.
Leave a 1/32-inch gap between the hatch end
formers and the fuselage formers.
Sheet the hatch and fuselage with 1/16
balsa. The sheeting should be beveled to fit
tight to the basswood pieces. As you install
the sheeting, cut it between F2A and F2B and
F6 and F6A. Cut the hatch free from the
fuselage.
Face the front and rear end of the hatch
and hatch opening with 1/64 plywood. Put
the hatch back in place, and sand the
basswood and plywood to match the
sheeting. Cut the sheeting aft of F7 to shape
for the cockpit, and trim the canopy to fit.
Laminate the 1/4 balsa SC1 through SC7.
Glue the subcowl to the front of F2. Glue the
F1 pieces in place. Sand the subcowl to shape.
Position the cowl formers on the front of
the fuselage crutch. The cowl is held in place
with two screws that go through C1, into the
firewall.
Cut 1/4 square balsa stringers and glue
them in place around the formers. Sheet the
cowl with 1/16 balsa. The sheeting extends 1/4
inch behind C4, and a strip of 1/64 plywood
reinforces it. The front of the cowl is
laminated from seven rings of 1/4 balsa and
sanded to shape.
Laminate two wing-joiner wedges from
three layers of 1/16 plywood. With the wing
joiner protected with waxed paper, slide one
wing into place and push a wedge in from the
opposite side. The wedges hold the wing
joiner against the bottom of the spar box and
distribute the flight loads to the fuselage
crutch.
Make adjustments, and glue the wedge to
the inside top of the spar box. Repeat for the
other wing and wedge.
Slide the wings in place, and check the fit
to the CR4s; use them to line up the stabilizer
before gluing it in place. Glue the top of F11
to the stabilizer.
Adhere the tail-filler piece in place. Glue
the fin assembly in place. Temporarily hinge
the rudder, and use balsa to fill the gap
between it and the tail-filler piece. Install the
rudder control before sheeting the sides of the
The bottom rear of the fuselage is sheeted
with 1/16 balsa. Glue F12 in place, and adhere
the 1/4 square spruce tail skid to it. Add the 1/4
balsa skids, and reinforce them with 1/64
plywood on each side.
The landing gear is finished with balsa
filler sandwiched between 1/16 balsa sheeting.
Sand the landing gear to an airfoil shape. Use
balsa or filler to create the fillets around the
landing gear. The fillet should be glued only
to the fuselage—not to the landing gear—so
it can flex.
The wheel pants are laminated and carved
from balsa. The 1/16 plywood plates provide a
mounting point for wheel pant hardware.
Final Assembly: Fit the wings to the
fuselage, and use a pin or machine screw
through the hole in the spar box and spars to
secure them in place. Use either balsa
triangle stock or your favorite filler to create
the small wing fillet.
The original LTR-14 was painted silver,
and most of the iron-on coverings offer a
close match. The fuselage rear is quite curvy,
so expect to use three or four pieces of
covering around it to get all the wrinkles out.
Self-adhesive vinyl graphics are available
from Callie Graphics. The Turner Special
had several sponsors during its racing career
and appeared as the “Pesco Special” and
“Ring Free Meteor.”
I have created the markings for the “Miss
Champion,” and the BMP files are available
on my Web site—T&J Models—for
download. I printed the images on waterslide
decal sheets.
It has been said that scale models are
never finished; you just stop working on
them. So how far you go with the cooling
scoops, cockpit, pilot, and engine detail is up
to you. When painting the pilot, you might
want to keep in mind that I’ve seen color film
of Roscoe Turner wearing a white leather
helmet.
Complete your radio installation at this
time. I use Hitec HS-55 servos for the
ailerons, HS-65s for the rudder and elevator,
and DS821s for the flaps. All of the servos
are hooked up to a Spektrum AR7000
receiver.
The power system I am using is providing
great results. It consists of a Hacker A30-
10XL motor; 14 x 7E APC propeller;
Skyshark R/C 5000 mAh 3S Li-Poly battery;
FMA Direct BalancePro Discharge
Protection Module; and Castle Creations
Phoenix-45 ESC and Ultimate BEC. This
setup draws approximately 36 amps static
and provides more than enough power.
If you are using flaps, you will need to
use a separate receiver battery or a switching
BEC, because few ESCs can supply enough
current for five servos. The battery capacity
might seem like overkill, but the LTR-14 has
a short nose moment, so I did need the
weight up front to balance it.
Flying: The Turner Special is an honest
airplane. The rudder is extremely effective,
and takeoffs from grass fields are no
problem, even without a steerable tail wheel.
Taxiing on grass takes only a bit of
throttle management to move the tail around.
With the recommended power system, the
Turner Special can take off from a three-point
stance and climbs out with authority.
For landings, set up your normal approach
and keep on a bit of power until the model is
over the field. Let the airplane settle in and
keep adding up-elevator, and it will give you
a pretty three-wheel landing. Remember to
save some power, to taxi the LTR-14 back to
the pits.
People might think that all racers can do
is go fast and turn left. I’m happy to report
that this is not the case with the Turner
Special.
This model is well behaved in the air
and has no bad stall tendencies. It will
perform any basic aerobatic maneuver
(loop, stall turn, point roll, Cuban 8, etc.).
With the balance point directly on the joiner
tube, the LTR-14 flies inverted hands off.
The large fuselage also makes extended
knife-edge flight possible.
I’d like to thank Keith Shaw for letting
me pick his brain along the way and for his
talented thumbs for the initial flights. MA
Jim Young
[email protected]
Sources:
Manzano Laser Works
(505) 286-2640
www.manzanolaser.com
Callie Graphics
(505) 281-9310
www.callie-graphics.com
T&J Models
(505) 286-2640
www.tnjmodels.rchomepage.com
Hacker Brushless
(480) 726-7519
www.hackerbrushless.com
APC Propellers
(530) 661-0399
www.apcprop.com
Skyshark R/C Corporation
(928) 854-6100
www.skysharkrc.com
FMA Direct
(800) 343-2934
www.fmadirect.com
Castle Creations
(913) 390-6939
www.castlecreations.com
Spektrum RC
(800) 338-4639
www.spektrumrc.com
Hitec RCD
(858) 748-6948
www.hitecrcd.com
Jim Young
(810) 231-1684
9356 Wendover Ct.
Brighton MI 4811

24 MODEL AVIATION
At roughly 1/6 scale, the LTR-14 is close in size to most
40-size models. The wings plug into the fuselage and
include working flaps.
Do you think all that racers can do
is go fast and turn left? Not this
one. Its large fuselage also makes
extended knife-edge flight possible.
12sig1.QXD_00MSTRPG.QXD 10/23/09 9:27 AM Page 24
IN JANUARY 2007, the E Zone and
Manzano Laser Works sponsored an electric-powered,
scale model “build-off.” This contest pitted designers around the
world against each other, to design, construct, and fly a scale model
in six months.
When the balsa dust settled, more than 20 new airplanes were flying (and
several others were still on the board). Online viewers had voted my LTR-14 Turner
Special the winner of the pro-civilian category.
Although Roscoe Turner might not have been the best pilot of his time, he was
the only one to win the Thompson Trophy race three times. Two of those victories
December 2009 25
Designed around
electric power, this
Thompson Trophywinning
replica scores
The Turner is well
behaved in the air
and has no bad stall
tendencies. It will
perform any basic
aerobatic maneuver.
The layout of the scale dashboard is included on the plans. The clear canopy and graphics
package are available from T&J Models.
Photos by the author
by Jim Young
12sig1.QXD_00MSTRPG.QXD 10/23/09 9:28 AM Page 25
26 MODEL AVIATION
17
Top: The stabilizer features built-up
construction under 1/32 balsa sheeting.
Elevators are left as open structures. A
laser-cut parts package is available from
the author.
Right: The amount of fun you have building
is your choice. Laser-cut parts are a work
of art, but a builder can make his or her
own from plans templates.
The fuselage starts with building the
internal crutch from spruce that extends
from the forward plywood frame.
Formers are threaded onto the completed
crutch assembly, and the frame begins to
lift off the board so it can rest back down
onto 4-inch-tall fixture blocks.
The fuselage rear is almost entirely balsa
stringers. Install the pushrods before
completely running the stringers.
A few stringers support the balsa
sheeting. Extending forward, they are
trimmed so that the joining sheeting fits
flush to the stringers.
The landing gear uses conventional music
wire and nylon mounting straps. The
bottom of the fuselage is finished off with
1/16 balsa sheeting.
Above: The fin is fairly wide at the base and
requires several ribs. The stabilizer and fin
outline is laminated from strips of 1/16 balsa.
Plywood plates on each side of the crutch
capture the torque rod ends of the landing
gear. Spruce crossmembers add support.
12sig1.QXD_00MSTRPG.QXD 10/23/09 9:29 AM Page 26
December 2009 27
A large hatch built into the fuselage’s top
allows easy access to the battery and radio. A
basswood rail provides a dent-resistant edge
to the hatch.
Graduated layers of balsa help shape the
removable cowl. It is built up with a few
formers and sheet balsa.
The intake scoops are a combination of laminated
material and carved balsa block. Any aluminum-colored
iron-on covering should give a reasonably scale
appearance.
The completed
airframe is light
and strong. The
wing panels
have a
f o a m
c o r e ,
which are available from the
author. The wheel pants are cut
and carved from balsa blocks, and
standard hardware is used to
mount them to the
landing gear.
Scale details such as the oil cooler scoops set the LTR-14
off at the field. In this case, the scoops are also functional
ram-air intakes for cooling the power system.
The author used Hitec HS-65 servos on the tail
surfaces, HS-55s for the ailerons, and a standard-size
servo on the flaps. A Hacker A30-10XL motor with a
3S battery turns an APC 14 x 7E propeller.
Add completed tail feathers to the
fuselage once the wing panels have been
mounted. Some 1/16 sheeting will close
and support the horizontal stabilizer.
Type: RC semiscale electric
Skill level: Intermediate builder and pilot
Wingspan: 51.4 inches
Wing area: 480 square inches
Length: 45.3 inches
Weight: 65 ounces
Wing loading: 20 ounces/square foot
Motor: 400-450 watts; 3S 5000 mAh Li-Poly battery
Radio: Six channels, five servos
Construction: Primarily
balsa, foam-core wing
Covering/finish: Heat-shrink
film
Other: 45-amp ESC,
14 x 7 APC propeller,
5-amp BEC
12sig1.QXD_00MSTRPG.QXD 10/23/09 9:35 AM Page 27
were in the Turner Special.
In 1936, feeling that his Wedell-
Williams racer could not get any faster,
Roscoe set out to build a new, all-out racing
machine. He entered a contract with Larry
Brown (of Miss Los Angeles fame) to build
a racer around the new twin-row Wasp
engine.
After almost two years and several
modifications, Matty Laird finally
completed the aircraft. He had it registered
as the LTR-14 (Laird Turner Racer), much
to Roscoe’s disappointment.
However, after sorting out the bugs,
Roscoe went on to win the 1938 and 1939
Thompson Trophy races piloting his
“Turner Special.”
CONSTRUCTION
This project requires modeling
experience and skill. To ease construction, I
have made a short kit of laser-cut parts,
foam wing cores, and vacuum-formed
canopy available from me. If you take on
fabricating those parts yourself, cutting your
own “kit” now will speed construction.
Tail Feathers: The stabilizer/elevator and
fin/rudder outlines are laminated from four
layers of 1/16 balsa. You can either cut a
cardboard template or use several pins
through the plans to form the outlines. I
used aliphatic glue and wet the strips, to
make them easier to bend.
Pin the stabilizer/elevator outline over
the plans, and cut and glue in place the
internal structure. The stabilizer is covered
top and bottom with 1/32 balsa sheeting,
while the elevators are left as open
structures.
Laminate the tail filler piece from 1/16
balsa. Sand a slot in the front of this piece,
to clear the elevator joiner wire.
Cut a 1/4-inch square balsa stick for the
rudder LE, and glue the rudder ribs to it. Fit
the laminated rudder outline to the ribs, and
glue it in place. Add balsa blocks to support
Robart hinge points.
Wrap the rudder LE with 1/16 balsa or
two layers of 1/32 balsa. You will need to
wet the balsa first, and pin or tape it in place
while it dries before gluing it in place. Add
balsa capstrips to the ribs. The rudder is
wide enough at the base to accommodate
pull-pull control, or install a control linkage
of your choice.
Glue fin ribs F1 through F7 to the 1/4
balsa fin post F8 and the laminated fin
outline. Temporarily hinge the rudder, and
cut some 1/4 balsa triangle stock to fit on
each side of the rudder to hide the hinge
line. Set these aside, to be glued in when the
fin is installed on the fuselage.
Wings: The wing has a foam core and is
sheeted with 1/16 balsa. A laminated
plywood wing joiner is built into each wing
panel. Laminate the two wing joiners from
three layers of 1/16 plywood. Sand the top
and bottom edges smooth.
Prepare the cores for sheeting by
beveling the root end 3°. Cut the cores to
accept the wing joiners. Glue the wing
joiner, root ribs, and subribs to the cores.
Glue the wingtip core to the root assembly.
Cut slots for the aileron extensions and
lay them in place. Protect them at the root
rib with heat-shrink tubing or electrical tape.
Sheet the wing with 1/16 balsa, using
your favorite method. I recommend epoxy
or Gorilla Glue and the vacuum-bag
technique.
Cut the ailerons and flaps free from the
wing. Face the wing LE and TE with 1/4
balsa. Similarly, face the LE of the ailerons
and flaps. True the ends of the ailerons and
the tip end of the flaps, and face them with
1/16 balsa.
The root ends of the flaps have a pocket
built into them, to receive the control rod.
Remove approximately 1/2 of the foam core
from the root end of the flap.
The inside of the bottom skin is
reinforced with 1/64 plywood. Use a 1/16
shim, and fill the remaining space above it
with balsa block. Sand a bevel (roughly 1/8
inch) along the lower LE of the flaps. Hinge
the flaps to the wing along this line.
Cut balsa block for the wingtips, and
glue them in place. I reinforced the TE of
the wingtips by cutting a slot with a razor
saw and gluing in a small piece of 1/64
plywood. Sand everything away that doesn’t
look like a wingtip. Cut an opening for the
aileron servos, and make hatches from 1/16
plywood.
Fuselage: The fuselage is framed up over an
internal crutch; 1/8 x 1/4 spruce longerons are
glued to the crutch sides. Fit the radio tray
CR1s and spar box pieces SB1s and SB2 to
the sides. Position the crutch assembly over
the plans and pin it in place before gluing.
Cut the longerons to length, taper the ends,
and glue them together. Cut and glue the balsa
crossbraces and diagonal braces between the
longerons.
Laminate the plywood landing gear
mounts and two 1/8 x 1/4 spruce sticks together.
Glue F2A and F3A in place between the
crutch sides. Laminate the 1/16 plywood torque
blocks together and epoxy them in place on
the inside of the crutch sides. Epoxy the
landing gear mount in place.
Remove the assembly from the board.
Glue the remaining crutch pieces in place,
using the fuselage formers to align them. Glue
the fuselage formers and motor mount in
place. Add triangle-stock reinforcements to all
motor-mount joints.
Bend the flap torque rods from 1/16-inchdiameter
music wire, using inner Nyrods for a
bearing. Insert the torque rods into the holes in
the crutch sides, and glue the wing-root plates
CR4s in place. Glue the torque-rod sleeve in
place, and brace them near the slots in the
radio tray.
Cut three fixture blocks from 4-inch-wide,
1/2 balsa, and fixture the fuselage over the
plans. Bend the landing gear from 5/32-inchdiameter
music wire and secure in place with
a pair of nylon straps and screws.
Glue the balsa diagonal braces from F7 to
F10. Start installing the 3/32 x 3/16 balsa rear
stringers. Each stringer is notched to half its
depth at F7 and F11 and extends at least 1
inch past these formers.
Glue three 1/4 square balsa stringers into
the notches from F2 to F7. Add scrap balsa to
the inside edges of the CR4s, to aid in gluing
the fuselage sheeting.
The fuselage has a gentle compound
curve, but you should attain good results with
four 3-inch-wide pieces of 1/16 balsa. The
fuselage should now be stable enough to be
removed from the fixtures.
Finish installing the upper rear stringers.
The edges of the cockpit are framed with
scrap balsa.
A large access hatch is built into the top of
the fuselage. Cut four pieces of 1/16 basswood
for the hatch edges; they should be oversized
in width. Glue the bottom piece and F6 into
the fuselage structure.
Use waxed paper and set the top piece in
place, and glue the hatch formers in place.
Leave a 1/32-inch gap between the hatch end
formers and the fuselage formers.
Sheet the hatch and fuselage with 1/16
balsa. The sheeting should be beveled to fit
tight to the basswood pieces. As you install
the sheeting, cut it between F2A and F2B and
F6 and F6A. Cut the hatch free from the
fuselage.
Face the front and rear end of the hatch
and hatch opening with 1/64 plywood. Put
the hatch back in place, and sand the
basswood and plywood to match the
sheeting. Cut the sheeting aft of F7 to shape
for the cockpit, and trim the canopy to fit.
Laminate the 1/4 balsa SC1 through SC7.
Glue the subcowl to the front of F2. Glue the
F1 pieces in place. Sand the subcowl to shape.
Position the cowl formers on the front of
the fuselage crutch. The cowl is held in place
with two screws that go through C1, into the
firewall.
Cut 1/4 square balsa stringers and glue
them in place around the formers. Sheet the
cowl with 1/16 balsa. The sheeting extends 1/4
inch behind C4, and a strip of 1/64 plywood
reinforces it. The front of the cowl is
laminated from seven rings of 1/4 balsa and
sanded to shape.
Laminate two wing-joiner wedges from
three layers of 1/16 plywood. With the wing
joiner protected with waxed paper, slide one
wing into place and push a wedge in from the
opposite side. The wedges hold the wing
joiner against the bottom of the spar box and
distribute the flight loads to the fuselage
crutch.
Make adjustments, and glue the wedge to
the inside top of the spar box. Repeat for the
other wing and wedge.
Slide the wings in place, and check the fit
to the CR4s; use them to line up the stabilizer
before gluing it in place. Glue the top of F11
to the stabilizer.
Adhere the tail-filler piece in place. Glue
the fin assembly in place. Temporarily hinge
the rudder, and use balsa to fill the gap
between it and the tail-filler piece. Install the
rudder control before sheeting the sides of the
The bottom rear of the fuselage is sheeted
with 1/16 balsa. Glue F12 in place, and adhere
the 1/4 square spruce tail skid to it. Add the 1/4
balsa skids, and reinforce them with 1/64
plywood on each side.
The landing gear is finished with balsa
filler sandwiched between 1/16 balsa sheeting.
Sand the landing gear to an airfoil shape. Use
balsa or filler to create the fillets around the
landing gear. The fillet should be glued only
to the fuselage—not to the landing gear—so
it can flex.
The wheel pants are laminated and carved
from balsa. The 1/16 plywood plates provide a
mounting point for wheel pant hardware.
Final Assembly: Fit the wings to the
fuselage, and use a pin or machine screw
through the hole in the spar box and spars to
secure them in place. Use either balsa
triangle stock or your favorite filler to create
the small wing fillet.
The original LTR-14 was painted silver,
and most of the iron-on coverings offer a
close match. The fuselage rear is quite curvy,
so expect to use three or four pieces of
covering around it to get all the wrinkles out.
Self-adhesive vinyl graphics are available
from Callie Graphics. The Turner Special
had several sponsors during its racing career
and appeared as the “Pesco Special” and
“Ring Free Meteor.”
I have created the markings for the “Miss
Champion,” and the BMP files are available
on my Web site—T&J Models—for
download. I printed the images on waterslide
decal sheets.
It has been said that scale models are
never finished; you just stop working on
them. So how far you go with the cooling
scoops, cockpit, pilot, and engine detail is up
to you. When painting the pilot, you might
want to keep in mind that I’ve seen color film
of Roscoe Turner wearing a white leather
helmet.
Complete your radio installation at this
time. I use Hitec HS-55 servos for the
ailerons, HS-65s for the rudder and elevator,
and DS821s for the flaps. All of the servos
are hooked up to a Spektrum AR7000
receiver.
The power system I am using is providing
great results. It consists of a Hacker A30-
10XL motor; 14 x 7E APC propeller;
Skyshark R/C 5000 mAh 3S Li-Poly battery;
FMA Direct BalancePro Discharge
Protection Module; and Castle Creations
Phoenix-45 ESC and Ultimate BEC. This
setup draws approximately 36 amps static
and provides more than enough power.
If you are using flaps, you will need to
use a separate receiver battery or a switching
BEC, because few ESCs can supply enough
current for five servos. The battery capacity
might seem like overkill, but the LTR-14 has
a short nose moment, so I did need the
weight up front to balance it.
Flying: The Turner Special is an honest
airplane. The rudder is extremely effective,
and takeoffs from grass fields are no
problem, even without a steerable tail wheel.
Taxiing on grass takes only a bit of
throttle management to move the tail around.
With the recommended power system, the
Turner Special can take off from a three-point
stance and climbs out with authority.
For landings, set up your normal approach
and keep on a bit of power until the model is
over the field. Let the airplane settle in and
keep adding up-elevator, and it will give you
a pretty three-wheel landing. Remember to
save some power, to taxi the LTR-14 back to
the pits.
People might think that all racers can do
is go fast and turn left. I’m happy to report
that this is not the case with the Turner
Special.
This model is well behaved in the air
and has no bad stall tendencies. It will
perform any basic aerobatic maneuver
(loop, stall turn, point roll, Cuban 8, etc.).
With the balance point directly on the joiner
tube, the LTR-14 flies inverted hands off.
The large fuselage also makes extended
knife-edge flight possible.
I’d like to thank Keith Shaw for letting
me pick his brain along the way and for his
talented thumbs for the initial flights. MA
Jim Young
[email protected]
Sources:
Manzano Laser Works
(505) 286-2640
www.manzanolaser.com
Callie Graphics
(505) 281-9310
www.callie-graphics.com
T&J Models
(505) 286-2640
www.tnjmodels.rchomepage.com
Hacker Brushless
(480) 726-7519
www.hackerbrushless.com
APC Propellers
(530) 661-0399
www.apcprop.com
Skyshark R/C Corporation
(928) 854-6100
www.skysharkrc.com
FMA Direct
(800) 343-2934
www.fmadirect.com
Castle Creations
(913) 390-6939
www.castlecreations.com
Spektrum RC
(800) 338-4639
www.spektrumrc.com
Hitec RCD
(858) 748-6948
www.hitecrcd.com
Jim Young
(810) 231-1684
9356 Wendover Ct.
Brighton MI 4811

24 MODEL AVIATION
At roughly 1/6 scale, the LTR-14 is close in size to most
40-size models. The wings plug into the fuselage and
include working flaps.
Do you think all that racers can do
is go fast and turn left? Not this
one. Its large fuselage also makes
extended knife-edge flight possible.
12sig1.QXD_00MSTRPG.QXD 10/23/09 9:27 AM Page 24
IN JANUARY 2007, the E Zone and
Manzano Laser Works sponsored an electric-powered,
scale model “build-off.” This contest pitted designers around the
world against each other, to design, construct, and fly a scale model
in six months.
When the balsa dust settled, more than 20 new airplanes were flying (and
several others were still on the board). Online viewers had voted my LTR-14 Turner
Special the winner of the pro-civilian category.
Although Roscoe Turner might not have been the best pilot of his time, he was
the only one to win the Thompson Trophy race three times. Two of those victories
December 2009 25
Designed around
electric power, this
Thompson Trophywinning
replica scores
The Turner is well
behaved in the air
and has no bad stall
tendencies. It will
perform any basic
aerobatic maneuver.
The layout of the scale dashboard is included on the plans. The clear canopy and graphics
package are available from T&J Models.
Photos by the author
by Jim Young
12sig1.QXD_00MSTRPG.QXD 10/23/09 9:28 AM Page 25
26 MODEL AVIATION
17
Top: The stabilizer features built-up
construction under 1/32 balsa sheeting.
Elevators are left as open structures. A
laser-cut parts package is available from
the author.
Right: The amount of fun you have building
is your choice. Laser-cut parts are a work
of art, but a builder can make his or her
own from plans templates.
The fuselage starts with building the
internal crutch from spruce that extends
from the forward plywood frame.
Formers are threaded onto the completed
crutch assembly, and the frame begins to
lift off the board so it can rest back down
onto 4-inch-tall fixture blocks.
The fuselage rear is almost entirely balsa
stringers. Install the pushrods before
completely running the stringers.
A few stringers support the balsa
sheeting. Extending forward, they are
trimmed so that the joining sheeting fits
flush to the stringers.
The landing gear uses conventional music
wire and nylon mounting straps. The
bottom of the fuselage is finished off with
1/16 balsa sheeting.
Above: The fin is fairly wide at the base and
requires several ribs. The stabilizer and fin
outline is laminated from strips of 1/16 balsa.
Plywood plates on each side of the crutch
capture the torque rod ends of the landing
gear. Spruce crossmembers add support.
12sig1.QXD_00MSTRPG.QXD 10/23/09 9:29 AM Page 26
December 2009 27
A large hatch built into the fuselage’s top
allows easy access to the battery and radio. A
basswood rail provides a dent-resistant edge
to the hatch.
Graduated layers of balsa help shape the
removable cowl. It is built up with a few
formers and sheet balsa.
The intake scoops are a combination of laminated
material and carved balsa block. Any aluminum-colored
iron-on covering should give a reasonably scale
appearance.
The completed
airframe is light
and strong. The
wing panels
have a
f o a m
c o r e ,
which are available from the
author. The wheel pants are cut
and carved from balsa blocks, and
standard hardware is used to
mount them to the
landing gear.
Scale details such as the oil cooler scoops set the LTR-14
off at the field. In this case, the scoops are also functional
ram-air intakes for cooling the power system.
The author used Hitec HS-65 servos on the tail
surfaces, HS-55s for the ailerons, and a standard-size
servo on the flaps. A Hacker A30-10XL motor with a
3S battery turns an APC 14 x 7E propeller.
Add completed tail feathers to the
fuselage once the wing panels have been
mounted. Some 1/16 sheeting will close
and support the horizontal stabilizer.
Type: RC semiscale electric
Skill level: Intermediate builder and pilot
Wingspan: 51.4 inches
Wing area: 480 square inches
Length: 45.3 inches
Weight: 65 ounces
Wing loading: 20 ounces/square foot
Motor: 400-450 watts; 3S 5000 mAh Li-Poly battery
Radio: Six channels, five servos
Construction: Primarily
balsa, foam-core wing
Covering/finish: Heat-shrink
film
Other: 45-amp ESC,
14 x 7 APC propeller,
5-amp BEC
12sig1.QXD_00MSTRPG.QXD 10/23/09 9:35 AM Page 27
were in the Turner Special.
In 1936, feeling that his Wedell-
Williams racer could not get any faster,
Roscoe set out to build a new, all-out racing
machine. He entered a contract with Larry
Brown (of Miss Los Angeles fame) to build
a racer around the new twin-row Wasp
engine.
After almost two years and several
modifications, Matty Laird finally
completed the aircraft. He had it registered
as the LTR-14 (Laird Turner Racer), much
to Roscoe’s disappointment.
However, after sorting out the bugs,
Roscoe went on to win the 1938 and 1939
Thompson Trophy races piloting his
“Turner Special.”
CONSTRUCTION
This project requires modeling
experience and skill. To ease construction, I
have made a short kit of laser-cut parts,
foam wing cores, and vacuum-formed
canopy available from me. If you take on
fabricating those parts yourself, cutting your
own “kit” now will speed construction.
Tail Feathers: The stabilizer/elevator and
fin/rudder outlines are laminated from four
layers of 1/16 balsa. You can either cut a
cardboard template or use several pins
through the plans to form the outlines. I
used aliphatic glue and wet the strips, to
make them easier to bend.
Pin the stabilizer/elevator outline over
the plans, and cut and glue in place the
internal structure. The stabilizer is covered
top and bottom with 1/32 balsa sheeting,
while the elevators are left as open
structures.
Laminate the tail filler piece from 1/16
balsa. Sand a slot in the front of this piece,
to clear the elevator joiner wire.
Cut a 1/4-inch square balsa stick for the
rudder LE, and glue the rudder ribs to it. Fit
the laminated rudder outline to the ribs, and
glue it in place. Add balsa blocks to support
Robart hinge points.
Wrap the rudder LE with 1/16 balsa or
two layers of 1/32 balsa. You will need to
wet the balsa first, and pin or tape it in place
while it dries before gluing it in place. Add
balsa capstrips to the ribs. The rudder is
wide enough at the base to accommodate
pull-pull control, or install a control linkage
of your choice.
Glue fin ribs F1 through F7 to the 1/4
balsa fin post F8 and the laminated fin
outline. Temporarily hinge the rudder, and
cut some 1/4 balsa triangle stock to fit on
each side of the rudder to hide the hinge
line. Set these aside, to be glued in when the
fin is installed on the fuselage.
Wings: The wing has a foam core and is
sheeted with 1/16 balsa. A laminated
plywood wing joiner is built into each wing
panel. Laminate the two wing joiners from
three layers of 1/16 plywood. Sand the top
and bottom edges smooth.
Prepare the cores for sheeting by
beveling the root end 3°. Cut the cores to
accept the wing joiners. Glue the wing
joiner, root ribs, and subribs to the cores.
Glue the wingtip core to the root assembly.
Cut slots for the aileron extensions and
lay them in place. Protect them at the root
rib with heat-shrink tubing or electrical tape.
Sheet the wing with 1/16 balsa, using
your favorite method. I recommend epoxy
or Gorilla Glue and the vacuum-bag
technique.
Cut the ailerons and flaps free from the
wing. Face the wing LE and TE with 1/4
balsa. Similarly, face the LE of the ailerons
and flaps. True the ends of the ailerons and
the tip end of the flaps, and face them with
1/16 balsa.
The root ends of the flaps have a pocket
built into them, to receive the control rod.
Remove approximately 1/2 of the foam core
from the root end of the flap.
The inside of the bottom skin is
reinforced with 1/64 plywood. Use a 1/16
shim, and fill the remaining space above it
with balsa block. Sand a bevel (roughly 1/8
inch) along the lower LE of the flaps. Hinge
the flaps to the wing along this line.
Cut balsa block for the wingtips, and
glue them in place. I reinforced the TE of
the wingtips by cutting a slot with a razor
saw and gluing in a small piece of 1/64
plywood. Sand everything away that doesn’t
look like a wingtip. Cut an opening for the
aileron servos, and make hatches from 1/16
plywood.
Fuselage: The fuselage is framed up over an
internal crutch; 1/8 x 1/4 spruce longerons are
glued to the crutch sides. Fit the radio tray
CR1s and spar box pieces SB1s and SB2 to
the sides. Position the crutch assembly over
the plans and pin it in place before gluing.
Cut the longerons to length, taper the ends,
and glue them together. Cut and glue the balsa
crossbraces and diagonal braces between the
longerons.
Laminate the plywood landing gear
mounts and two 1/8 x 1/4 spruce sticks together.
Glue F2A and F3A in place between the
crutch sides. Laminate the 1/16 plywood torque
blocks together and epoxy them in place on
the inside of the crutch sides. Epoxy the
landing gear mount in place.
Remove the assembly from the board.
Glue the remaining crutch pieces in place,
using the fuselage formers to align them. Glue
the fuselage formers and motor mount in
place. Add triangle-stock reinforcements to all
motor-mount joints.
Bend the flap torque rods from 1/16-inchdiameter
music wire, using inner Nyrods for a
bearing. Insert the torque rods into the holes in
the crutch sides, and glue the wing-root plates
CR4s in place. Glue the torque-rod sleeve in
place, and brace them near the slots in the
radio tray.
Cut three fixture blocks from 4-inch-wide,
1/2 balsa, and fixture the fuselage over the
plans. Bend the landing gear from 5/32-inchdiameter
music wire and secure in place with
a pair of nylon straps and screws.
Glue the balsa diagonal braces from F7 to
F10. Start installing the 3/32 x 3/16 balsa rear
stringers. Each stringer is notched to half its
depth at F7 and F11 and extends at least 1
inch past these formers.
Glue three 1/4 square balsa stringers into
the notches from F2 to F7. Add scrap balsa to
the inside edges of the CR4s, to aid in gluing
the fuselage sheeting.
The fuselage has a gentle compound
curve, but you should attain good results with
four 3-inch-wide pieces of 1/16 balsa. The
fuselage should now be stable enough to be
removed from the fixtures.
Finish installing the upper rear stringers.
The edges of the cockpit are framed with
scrap balsa.
A large access hatch is built into the top of
the fuselage. Cut four pieces of 1/16 basswood
for the hatch edges; they should be oversized
in width. Glue the bottom piece and F6 into
the fuselage structure.
Use waxed paper and set the top piece in
place, and glue the hatch formers in place.
Leave a 1/32-inch gap between the hatch end
formers and the fuselage formers.
Sheet the hatch and fuselage with 1/16
balsa. The sheeting should be beveled to fit
tight to the basswood pieces. As you install
the sheeting, cut it between F2A and F2B and
F6 and F6A. Cut the hatch free from the
fuselage.
Face the front and rear end of the hatch
and hatch opening with 1/64 plywood. Put
the hatch back in place, and sand the
basswood and plywood to match the
sheeting. Cut the sheeting aft of F7 to shape
for the cockpit, and trim the canopy to fit.
Laminate the 1/4 balsa SC1 through SC7.
Glue the subcowl to the front of F2. Glue the
F1 pieces in place. Sand the subcowl to shape.
Position the cowl formers on the front of
the fuselage crutch. The cowl is held in place
with two screws that go through C1, into the
firewall.
Cut 1/4 square balsa stringers and glue
them in place around the formers. Sheet the
cowl with 1/16 balsa. The sheeting extends 1/4
inch behind C4, and a strip of 1/64 plywood
reinforces it. The front of the cowl is
laminated from seven rings of 1/4 balsa and
sanded to shape.
Laminate two wing-joiner wedges from
three layers of 1/16 plywood. With the wing
joiner protected with waxed paper, slide one
wing into place and push a wedge in from the
opposite side. The wedges hold the wing
joiner against the bottom of the spar box and
distribute the flight loads to the fuselage
crutch.
Make adjustments, and glue the wedge to
the inside top of the spar box. Repeat for the
other wing and wedge.
Slide the wings in place, and check the fit
to the CR4s; use them to line up the stabilizer
before gluing it in place. Glue the top of F11
to the stabilizer.
Adhere the tail-filler piece in place. Glue
the fin assembly in place. Temporarily hinge
the rudder, and use balsa to fill the gap
between it and the tail-filler piece. Install the
rudder control before sheeting the sides of the
The bottom rear of the fuselage is sheeted
with 1/16 balsa. Glue F12 in place, and adhere
the 1/4 square spruce tail skid to it. Add the 1/4
balsa skids, and reinforce them with 1/64
plywood on each side.
The landing gear is finished with balsa
filler sandwiched between 1/16 balsa sheeting.
Sand the landing gear to an airfoil shape. Use
balsa or filler to create the fillets around the
landing gear. The fillet should be glued only
to the fuselage—not to the landing gear—so
it can flex.
The wheel pants are laminated and carved
from balsa. The 1/16 plywood plates provide a
mounting point for wheel pant hardware.
Final Assembly: Fit the wings to the
fuselage, and use a pin or machine screw
through the hole in the spar box and spars to
secure them in place. Use either balsa
triangle stock or your favorite filler to create
the small wing fillet.
The original LTR-14 was painted silver,
and most of the iron-on coverings offer a
close match. The fuselage rear is quite curvy,
so expect to use three or four pieces of
covering around it to get all the wrinkles out.
Self-adhesive vinyl graphics are available
from Callie Graphics. The Turner Special
had several sponsors during its racing career
and appeared as the “Pesco Special” and
“Ring Free Meteor.”
I have created the markings for the “Miss
Champion,” and the BMP files are available
on my Web site—T&J Models—for
download. I printed the images on waterslide
decal sheets.
It has been said that scale models are
never finished; you just stop working on
them. So how far you go with the cooling
scoops, cockpit, pilot, and engine detail is up
to you. When painting the pilot, you might
want to keep in mind that I’ve seen color film
of Roscoe Turner wearing a white leather
helmet.
Complete your radio installation at this
time. I use Hitec HS-55 servos for the
ailerons, HS-65s for the rudder and elevator,
and DS821s for the flaps. All of the servos
are hooked up to a Spektrum AR7000
receiver.
The power system I am using is providing
great results. It consists of a Hacker A30-
10XL motor; 14 x 7E APC propeller;
Skyshark R/C 5000 mAh 3S Li-Poly battery;
FMA Direct BalancePro Discharge
Protection Module; and Castle Creations
Phoenix-45 ESC and Ultimate BEC. This
setup draws approximately 36 amps static
and provides more than enough power.
If you are using flaps, you will need to
use a separate receiver battery or a switching
BEC, because few ESCs can supply enough
current for five servos. The battery capacity
might seem like overkill, but the LTR-14 has
a short nose moment, so I did need the
weight up front to balance it.
Flying: The Turner Special is an honest
airplane. The rudder is extremely effective,
and takeoffs from grass fields are no
problem, even without a steerable tail wheel.
Taxiing on grass takes only a bit of
throttle management to move the tail around.
With the recommended power system, the
Turner Special can take off from a three-point
stance and climbs out with authority.
For landings, set up your normal approach
and keep on a bit of power until the model is
over the field. Let the airplane settle in and
keep adding up-elevator, and it will give you
a pretty three-wheel landing. Remember to
save some power, to taxi the LTR-14 back to
the pits.
People might think that all racers can do
is go fast and turn left. I’m happy to report
that this is not the case with the Turner
Special.
This model is well behaved in the air
and has no bad stall tendencies. It will
perform any basic aerobatic maneuver
(loop, stall turn, point roll, Cuban 8, etc.).
With the balance point directly on the joiner
tube, the LTR-14 flies inverted hands off.
The large fuselage also makes extended
knife-edge flight possible.
I’d like to thank Keith Shaw for letting
me pick his brain along the way and for his
talented thumbs for the initial flights. MA
Jim Young
[email protected]
Sources:
Manzano Laser Works
(505) 286-2640
www.manzanolaser.com
Callie Graphics
(505) 281-9310
www.callie-graphics.com
T&J Models
(505) 286-2640
www.tnjmodels.rchomepage.com
Hacker Brushless
(480) 726-7519
www.hackerbrushless.com
APC Propellers
(530) 661-0399
www.apcprop.com
Skyshark R/C Corporation
(928) 854-6100
www.skysharkrc.com
FMA Direct
(800) 343-2934
www.fmadirect.com
Castle Creations
(913) 390-6939
www.castlecreations.com
Spektrum RC
(800) 338-4639
www.spektrumrc.com
Hitec RCD
(858) 748-6948
www.hitecrcd.com
Jim Young
(810) 231-1684
9356 Wendover Ct.
Brighton MI 4811