Texan II - 2010/02

RUBBER SCALE modelers are always in
search of the “perfect subject.” The modeled
airplane must be charismatic, well
documented, and, most important, possess
good areas and moments, to assure
successful flight performance. Additionally,
the aircraft must offer some promise of ease
of construction as the plans are developed.
The Raytheon/Beechcraft Texan II, a
turbo-powered trainer, is currently in use by
the US Air Force and meets all of the
requirements I mentioned. I live in Katy,
Texas, and own a ranch near Del Rio,
Texas, which is home of the 47th Flying
Training Wing at Laughlin Air Force Base.
Texan IIs are constantly in the air around
Del Rio, and I have spent several hours
watching the sleek trainers shoot approaches
and practice touch-and-gos at Laughlin.
I made contact with Captain Ken Hall,
chief of public affairs at Laughlin, and
Kent Cummings, chief of community and
media relations, who allowed me to take
photos of a Texan II on the flightline for
authentication of the model I’m
presenting in this article.
My thanks to the personnel at
Laughlin—especially Carl Riordan, T-6
maintenance work leader, and Mark
Escobar, aircraft sign painter—who were
very cooperative in helping me obtain some
details that are not currently available on
the Internet.
The Texan II is a development/redesign
of the Pilatus PC-9: a trainer that several
countries currently use. With slight
modifications to the fins and canopy
framing, the model in this feature can be
built as a PC-9. A Google search will yield
a myriad of mouthwatering PC-9 color
schemes that beg to be replicated on a
model.
While researching the Texan II, I found
references indicating that the Pilatus is a
direct descendant of the Arado Ar.96
German World War II trainer. My last
article published in MA, in the December
2005 issue, was about an Ar.96. The design
similarities are astonishing, and the Arado
was conceived in 1938.
CONSTRUCTION
A quick glance at the Texan II’s plans
reveal its low wing placement, which is
ideal for conversion to an RC electricpowered
park flyer. There is plenty of room
for miniature servos, and the rudder and
elevator surfaces can be hinged by simply
doubling their respective spars.
For rubber-power enthusiasts, the CG
Type: Scale rubber-powered FF
Skill level: Intermediate
Wingspan: 25.25 inches
Wing area: 120 square inches
Airfoil: Wing, modified Neelmeyer; stabilizer,
5% cambered
Length: 25 inches
Weight without rubber: 50 grams
Motor: Three loops of 1/8-inch Tan Super
Sport, 40 inches long, braided
Construction: Primarily balsa with 1/32
plywood reinforcement
Propeller: Hand-carved balsa with 1:11/4
pitch-to-diameter ratio
Finish: Esaki tissue, dope for color
Trim: Right/right
sits almost exactly halfway between the
model’s rear peg and nose—perfect for a
long motor. Let’s begin.
Fuselage: The fuselage build is based on the
conventional box/former method. All of the
components are constructed from 1/16 balsa
except for the nose blocks, so it will be
unnecessary to raid the piggy bank to
purchase several thicknesses of balsa.
Pin down and build one fuselage side on
top of the other, noting that all verticals on
the box are the same length. I made a stop
on a miter box and cut all the verticals at one
time.
Also notice that the rear peg support can
be cut at the same time as the 1/16 uprights.
The fuselage longerons are straight, except
for the rear of the top longeron. It can be
notched and “cracked” to match the
fuselage/rudder rear line.
After the sides are completed/separated,
pin them to the top view on the plans and
add the crosspieces in the cabin area. Use a
square to keep the sides square and vertical.
When the cement is dry on the
crosspieces, glue the tail and front
crosspieces in place, making sure that the
nose and tail are square and centered on the
plans. Add the remaining crosspieces, front
and rear, checking for squareness at each
station.
At this point, I spray the completed
structure with a mist of water while it is still
pinned. This relieves any built-in stresses in
the balsa construction and results in a true
fuselage. No bananas wanted here.
I should mention that the plans are
covered with waxed paper before any
construction commences.
When the stress-relieved structure is dry,
add the bottom formers, front to rear. As
shown on the plans, the formers are
purposely slightly oversize. I typically make
a copy of the formers on bond paper and use
rubber cement to attach the copies to the
appropriate thickness of balsa sheet.
After cutting the formers from the sheet,
I can easily peel off the paper copies. Slight
rubbing removes the rubber cement residue
from the balsa.
The oversize formers are centered on
each station. When dry, they are sanded to
blend perfectly with the fuselage sides and
each other.
I add the center stringer, making sure that
it is straight front to rear, and then I add the
remaining stringers, alternating from side to
side, measuring to assure symmetry. I use a
small Swiss File to notch the formers and
get a perfect fit for each stringer.
After the bottom stringers are in place
and dry, remove/unpin the fuselage from the
plans. Add the top formers in the same
manner as the bottom.
The cockpit flooring is made from
extremely light 1/32 balsa, applied crossgrained
to the box. Laminate the 1/8 balsa for
the nose block, and add it and the bottom
chin block to the fuselage.
Leave these components slightly
oversize, add the 1/32 plywood nose ring to
the front of the assembly, and carefully
sand/blend them to the fuselage. Use the
plans and photos to obtain the correct side
and top profile.
I drilled the initial undersized hole for
the nose plug using a router bit with a
Dremel tool. Then I finished/sized the hole
using a sandpaper-wrapped dowel.
The exhaust stacks are made from scrap
balsa that is as thick as the widest portion of
the exhaust. I made copies of the top view of
the exhausts on bond paper, rubbercemented
them to the scrap balsa, and
jigsawed them to shape.
Carve/sand away anything that does not
look like an exhaust stack. I employed a
Dremel cutter to hollow out the stacks’
interior.
The stacks are one of the features that
gives the Texan its look, so take time to
shape them correctly. I used a circle
template to inscribe a ring on the inner
portion of the exhaust, where it is attached
to the fuselage. By carving and sanding the
balsa to that circle, the exhaust stacks will
quickly take on the desired profile.
The spinner is made utilizing a Dremel
tool. Use scissors to cut a piece of 1/32
plywood slightly larger than 13/8 inches in
diameter. Mount this on a Dremel arbor (the
one used for holding abrasive discs) and
sand it to exactly 13/8 inches.
Add an oversized balsa block to the
plywood disc using Ambroid or Duco
cement. (You will have to rout out a small
recess in the center of the block, to clear the
arbor screw.) Give the glue plenty of time to
dry completely.
Rough-shape the spinner block with an
X-Acto knife before beginning to spin it up.
Use a sanding block and light pressure to
shape the spinner, comparing its profile to
the plans. You must wear eye protection for
the preceding operation!
The nose plug is made from laminated 1/8
sheet. I made an oversize lamination and
used it for both the nose block and the nose
plug.
The nose plug is made in the same
manner as the spinner. A plywood disk is
spun/sanded to size (3/4 inch). Glue the
oversized, laminated balsa plug to the disk
and spin it to size, while checking to ensure
that it is a good fit to the nose block. Fit a
13/8-inch-diameter 1/32 plywood disk to the
front of the plug and glue it.
Drill the nose plug on center at the front
with the other end of the plug resting on a
41/4° wedge. When rotated correctly, the
plug will yield the desired 3° of downthrust
and right thrust. Install a brass tubing
bushing with an ID to match the propellershaft
OD in the drilled hole, and the nose
plug is complete.
Wing: Make a rib template. I fabricated
mine from 1/16 plywood, by copying the root
rib on bond paper and rubber-cementing the
reproduction to the plywood. I jigsawed the
template and carefully sanded it to the exact
profile.
Drive two straight pins through the
template, letting them project 1/16 inch below
the bottom surface. Use CA to adhere the
pins in place and cut them off above the top
surface. These pins are used to hold the
template to the appropriate balsa
thicknesses, so you can carefully cut around
the template with an X-Acto knife.
I cut every rib using the same template. I
made smaller/shorter ribs by rotating it TEdown,
to achieve the length measured from
the plans. The point of rotation is the center
of the LE notch.
Pin down the TE along its entire length
and add the ribs, making sure that they are
square to the building board. Add the LE in
the fish-mouth front of the ribs and the
wingtips. When that assembly is dry,
remove it from the building board and sight
over the top of the ribs, to make sure that
there is a uniform taper from root to wingtip.
Use a long sanding block to remove high
spots in the upper camber of the wing. At
this point, I use a steel straightedge to mark
the spar locations, and I notch the ribs for
the spars with a small Swiss File.
Glue the spars in place except for the
bottom spar on the outer wing sections. To
ensure that washout (TE high at the
wingtips) is permanently built into the
structure, pin the LE down and raise the TE
using the wedge shown on the plans. Glue
the bottom spar in place and you are there.
Sand a bevel on the outer wing-panel LE,
TE, and spars, to allow for the 2-inch
dihedral on each panel. Glue the outer wing
panels in place, measuring to assure that an
equal amount of dihedral is in place. Add
the dihedral braces and gussets, give the
wing a final touch-up sanding, and you are
finished.
Tail Feathers: The tail surfaces are built in
a similar manner, with one exception. The
rudder is built with a symmetrical airfoil, so
it is necessary to shim the LE and TE off of
the building board before adding the ribs.
The stabilizer is flat-bottomed, so you can
pin all components directly to the board.
After gluing in the ribs, the stabilizer is
airfoiled (the top surface only is cambered)
while the rudder is airfoiled (cambered) on
both sides. Cut the stabilizer strakes and
rudder forward fin, sand the appropriate
edges, and the tail surfaces are ready to
cover.
Propeller: Carve the propeller by hand,
using the profile shown on the plans. Jigsaw
the top “bowtie” profile and drill a 3/32-inchdiameter
hole in the center. Jigsaw the side
profile.
Begin carving with the back of the
propeller, carefully moving across corners.
Go slowly and make sure that both of the
propeller’s undersides are carved to match. I
use a small balsa sanding block with a 5%
arc on its upper surface to sand in a slight
undercamber on the blades.
Carve a camber on the top surface, using
your fingers and feel to attain the same
thickness on both blades. Spin/sand a 13/8-
inch-diameter 1/32 plywood backplate, and
enlarge the center hole to 3/32 inch.
Install the propeller on the backplate,
using 3/32-inch-OD brass tubing to bush both
the backplate and the propeller. Install a
larger brass-tube “clutch” over the bushing,
and the propeller is ready for finishing.
Add the hollowed-out balsa spinner or a
vacuum-formed version after you finish the
propeller, backplate, nose plug, shaft, and
bearing assembly. See the sketch of these
components for reference purposes.
Finishing: The traditional nitrate dope-and-
Esaki tissue method was used to finish the
Texan. I prepared all surfaces by coating
every one that would contact the tissue with
several coats of nitrate dope, sanding after
the first coat. I applied enough dope so that
the surfaces would appear glossy.
I applied the white Esaki tissue wet,
using 70% alcohol as the wetting agent. I
used thinner, brushed through the tissue, to
apply it to the airframe.
It is important to apply the thinner only
to the periphery of the surface that is being
covered. This allows the wet tissue to shrink
evenly and will result in a superior, wrinklefree
covering job. Tissue overlaps require a
second coat of dope on the overlapped
surface, to get the added tissue piece to
adhere properly.
After the tissue is stretched and dry,
brush it with a coat of nitrate that has
been thinned 50%. The red stripe on the
fuselage is a piece of red Esaki that is
applied with thinner and given a coat of
the 50/50 nitrate.
The blue fuselage bottom, wing
underside, top chevrons, and stabilizer
were airbrushed using the pigment from
Dark Blue Floquil model-train paint,
mixed into nitrate thinner and added to
clear nitrate dope. In the same manner,
the wing, stabilizer, and rudder LEs
were airbrushed with Old Silver Floquil.
Frisket paper was used to mask the
surfaces for all airbrushing.
I trimmed the canopy and attached it
to the finished model with Pacer
Formula 560 Canopy Glue. The spinner,
which I vacuum-formed from .030-inch
Vivak, was airbrushed on the inside with
chrome enamel, which is designed for
use on model-car bodies. I coated the
spinner with flat-black enamel, to give a
deep, polished look. I glued the spinner
to the propeller backplate with Formula
560.
I gave the propeller several coats of
clear nitrate mixed with talc to fill the
balsa grain. I airbrushed it with flatblack
enamel and then painted the tips
flat white.
I have vacuum-formed canopies,
spinners, and water-slide decals for the
Texan, as well as a tissue-covering DVD
for aeromodelers. I will also provide
assistance with questions concerning
construction details via e-mail. Please
preface all such correspondence with
“Texan II” in the subject line.
Flying: My Texan flew “off the board”
with little adjustment required. Remove
the propeller and add clay to the nose, to
get the CG correct. Test-glide the Texan
over high grass, by pointing it at a spot
close to 50 feet ahead and giving it a
firm toss toward that spot.
Cure diving or stalling with small
adjustments to the stabilizer decalage.
Cure unwanted turning/spiraling by
adding small bits of clay to the wingtip
opposite the turn.
When you are satisfied with the
glide, add the rubber motor (three loops
of 1/8-inch Tan Super Sport, 40 inches
long, braided). Recheck the CG and
wind in 450 turns. When released, the
model should climb and turn right; make
all adjustments by shimming the
thrustline.
As the airplane begins to behave, add
turns until you get to approximately
1,750. At this point, make sure that you
have binoculars available and a reliable
way to retrieve your model.
Good luck with your Texan II. MA
Bob Isaacks
[email protected]

RUBBER SCALE modelers are always in
search of the “perfect subject.” The modeled
airplane must be charismatic, well
documented, and, most important, possess
good areas and moments, to assure
successful flight performance. Additionally,
the aircraft must offer some promise of ease
of construction as the plans are developed.
The Raytheon/Beechcraft Texan II, a
turbo-powered trainer, is currently in use by
the US Air Force and meets all of the
requirements I mentioned. I live in Katy,
Texas, and own a ranch near Del Rio,
Texas, which is home of the 47th Flying
Training Wing at Laughlin Air Force Base.
Texan IIs are constantly in the air around
Del Rio, and I have spent several hours
watching the sleek trainers shoot approaches
and practice touch-and-gos at Laughlin.
I made contact with Captain Ken Hall,
chief of public affairs at Laughlin, and
Kent Cummings, chief of community and
media relations, who allowed me to take
photos of a Texan II on the flightline for
authentication of the model I’m
presenting in this article.
My thanks to the personnel at
Laughlin—especially Carl Riordan, T-6
maintenance work leader, and Mark
Escobar, aircraft sign painter—who were
very cooperative in helping me obtain some
details that are not currently available on
the Internet.
The Texan II is a development/redesign
of the Pilatus PC-9: a trainer that several
countries currently use. With slight
modifications to the fins and canopy
framing, the model in this feature can be
built as a PC-9. A Google search will yield
a myriad of mouthwatering PC-9 color
schemes that beg to be replicated on a
model.
While researching the Texan II, I found
references indicating that the Pilatus is a
direct descendant of the Arado Ar.96
German World War II trainer. My last
article published in MA, in the December
2005 issue, was about an Ar.96. The design
similarities are astonishing, and the Arado
was conceived in 1938.
CONSTRUCTION
A quick glance at the Texan II’s plans
reveal its low wing placement, which is
ideal for conversion to an RC electricpowered
park flyer. There is plenty of room
for miniature servos, and the rudder and
elevator surfaces can be hinged by simply
doubling their respective spars.
For rubber-power enthusiasts, the CG
Type: Scale rubber-powered FF
Skill level: Intermediate
Wingspan: 25.25 inches
Wing area: 120 square inches
Airfoil: Wing, modified Neelmeyer; stabilizer,
5% cambered
Length: 25 inches
Weight without rubber: 50 grams
Motor: Three loops of 1/8-inch Tan Super
Sport, 40 inches long, braided
Construction: Primarily balsa with 1/32
plywood reinforcement
Propeller: Hand-carved balsa with 1:11/4
pitch-to-diameter ratio
Finish: Esaki tissue, dope for color
Trim: Right/right
sits almost exactly halfway between the
model’s rear peg and nose—perfect for a
long motor. Let’s begin.
Fuselage: The fuselage build is based on the
conventional box/former method. All of the
components are constructed from 1/16 balsa
except for the nose blocks, so it will be
unnecessary to raid the piggy bank to
purchase several thicknesses of balsa.
Pin down and build one fuselage side on
top of the other, noting that all verticals on
the box are the same length. I made a stop
on a miter box and cut all the verticals at one
time.
Also notice that the rear peg support can
be cut at the same time as the 1/16 uprights.
The fuselage longerons are straight, except
for the rear of the top longeron. It can be
notched and “cracked” to match the
fuselage/rudder rear line.
After the sides are completed/separated,
pin them to the top view on the plans and
add the crosspieces in the cabin area. Use a
square to keep the sides square and vertical.
When the cement is dry on the
crosspieces, glue the tail and front
crosspieces in place, making sure that the
nose and tail are square and centered on the
plans. Add the remaining crosspieces, front
and rear, checking for squareness at each
station.
At this point, I spray the completed
structure with a mist of water while it is still
pinned. This relieves any built-in stresses in
the balsa construction and results in a true
fuselage. No bananas wanted here.
I should mention that the plans are
covered with waxed paper before any
construction commences.
When the stress-relieved structure is dry,
add the bottom formers, front to rear. As
shown on the plans, the formers are
purposely slightly oversize. I typically make
a copy of the formers on bond paper and use
rubber cement to attach the copies to the
appropriate thickness of balsa sheet.
After cutting the formers from the sheet,
I can easily peel off the paper copies. Slight
rubbing removes the rubber cement residue
from the balsa.
The oversize formers are centered on
each station. When dry, they are sanded to
blend perfectly with the fuselage sides and
each other.
I add the center stringer, making sure that
it is straight front to rear, and then I add the
remaining stringers, alternating from side to
side, measuring to assure symmetry. I use a
small Swiss File to notch the formers and
get a perfect fit for each stringer.
After the bottom stringers are in place
and dry, remove/unpin the fuselage from the
plans. Add the top formers in the same
manner as the bottom.
The cockpit flooring is made from
extremely light 1/32 balsa, applied crossgrained
to the box. Laminate the 1/8 balsa for
the nose block, and add it and the bottom
chin block to the fuselage.
Leave these components slightly
oversize, add the 1/32 plywood nose ring to
the front of the assembly, and carefully
sand/blend them to the fuselage. Use the
plans and photos to obtain the correct side
and top profile.
I drilled the initial undersized hole for
the nose plug using a router bit with a
Dremel tool. Then I finished/sized the hole
using a sandpaper-wrapped dowel.
The exhaust stacks are made from scrap
balsa that is as thick as the widest portion of
the exhaust. I made copies of the top view of
the exhausts on bond paper, rubbercemented
them to the scrap balsa, and
jigsawed them to shape.
Carve/sand away anything that does not
look like an exhaust stack. I employed a
Dremel cutter to hollow out the stacks’
interior.
The stacks are one of the features that
gives the Texan its look, so take time to
shape them correctly. I used a circle
template to inscribe a ring on the inner
portion of the exhaust, where it is attached
to the fuselage. By carving and sanding the
balsa to that circle, the exhaust stacks will
quickly take on the desired profile.
The spinner is made utilizing a Dremel
tool. Use scissors to cut a piece of 1/32
plywood slightly larger than 13/8 inches in
diameter. Mount this on a Dremel arbor (the
one used for holding abrasive discs) and
sand it to exactly 13/8 inches.
Add an oversized balsa block to the
plywood disc using Ambroid or Duco
cement. (You will have to rout out a small
recess in the center of the block, to clear the
arbor screw.) Give the glue plenty of time to
dry completely.
Rough-shape the spinner block with an
X-Acto knife before beginning to spin it up.
Use a sanding block and light pressure to
shape the spinner, comparing its profile to
the plans. You must wear eye protection for
the preceding operation!
The nose plug is made from laminated 1/8
sheet. I made an oversize lamination and
used it for both the nose block and the nose
plug.
The nose plug is made in the same
manner as the spinner. A plywood disk is
spun/sanded to size (3/4 inch). Glue the
oversized, laminated balsa plug to the disk
and spin it to size, while checking to ensure
that it is a good fit to the nose block. Fit a
13/8-inch-diameter 1/32 plywood disk to the
front of the plug and glue it.
Drill the nose plug on center at the front
with the other end of the plug resting on a
41/4° wedge. When rotated correctly, the
plug will yield the desired 3° of downthrust
and right thrust. Install a brass tubing
bushing with an ID to match the propellershaft
OD in the drilled hole, and the nose
plug is complete.
Wing: Make a rib template. I fabricated
mine from 1/16 plywood, by copying the root
rib on bond paper and rubber-cementing the
reproduction to the plywood. I jigsawed the
template and carefully sanded it to the exact
profile.
Drive two straight pins through the
template, letting them project 1/16 inch below
the bottom surface. Use CA to adhere the
pins in place and cut them off above the top
surface. These pins are used to hold the
template to the appropriate balsa
thicknesses, so you can carefully cut around
the template with an X-Acto knife.
I cut every rib using the same template. I
made smaller/shorter ribs by rotating it TEdown,
to achieve the length measured from
the plans. The point of rotation is the center
of the LE notch.
Pin down the TE along its entire length
and add the ribs, making sure that they are
square to the building board. Add the LE in
the fish-mouth front of the ribs and the
wingtips. When that assembly is dry,
remove it from the building board and sight
over the top of the ribs, to make sure that
there is a uniform taper from root to wingtip.
Use a long sanding block to remove high
spots in the upper camber of the wing. At
this point, I use a steel straightedge to mark
the spar locations, and I notch the ribs for
the spars with a small Swiss File.
Glue the spars in place except for the
bottom spar on the outer wing sections. To
ensure that washout (TE high at the
wingtips) is permanently built into the
structure, pin the LE down and raise the TE
using the wedge shown on the plans. Glue
the bottom spar in place and you are there.
Sand a bevel on the outer wing-panel LE,
TE, and spars, to allow for the 2-inch
dihedral on each panel. Glue the outer wing
panels in place, measuring to assure that an
equal amount of dihedral is in place. Add
the dihedral braces and gussets, give the
wing a final touch-up sanding, and you are
finished.
Tail Feathers: The tail surfaces are built in
a similar manner, with one exception. The
rudder is built with a symmetrical airfoil, so
it is necessary to shim the LE and TE off of
the building board before adding the ribs.
The stabilizer is flat-bottomed, so you can
pin all components directly to the board.
After gluing in the ribs, the stabilizer is
airfoiled (the top surface only is cambered)
while the rudder is airfoiled (cambered) on
both sides. Cut the stabilizer strakes and
rudder forward fin, sand the appropriate
edges, and the tail surfaces are ready to
cover.
Propeller: Carve the propeller by hand,
using the profile shown on the plans. Jigsaw
the top “bowtie” profile and drill a 3/32-inchdiameter
hole in the center. Jigsaw the side
profile.
Begin carving with the back of the
propeller, carefully moving across corners.
Go slowly and make sure that both of the
propeller’s undersides are carved to match. I
use a small balsa sanding block with a 5%
arc on its upper surface to sand in a slight
undercamber on the blades.
Carve a camber on the top surface, using
your fingers and feel to attain the same
thickness on both blades. Spin/sand a 13/8-
inch-diameter 1/32 plywood backplate, and
enlarge the center hole to 3/32 inch.
Install the propeller on the backplate,
using 3/32-inch-OD brass tubing to bush both
the backplate and the propeller. Install a
larger brass-tube “clutch” over the bushing,
and the propeller is ready for finishing.
Add the hollowed-out balsa spinner or a
vacuum-formed version after you finish the
propeller, backplate, nose plug, shaft, and
bearing assembly. See the sketch of these
components for reference purposes.
Finishing: The traditional nitrate dope-and-
Esaki tissue method was used to finish the
Texan. I prepared all surfaces by coating
every one that would contact the tissue with
several coats of nitrate dope, sanding after
the first coat. I applied enough dope so that
the surfaces would appear glossy.
I applied the white Esaki tissue wet,
using 70% alcohol as the wetting agent. I
used thinner, brushed through the tissue, to
apply it to the airframe.
It is important to apply the thinner only
to the periphery of the surface that is being
covered. This allows the wet tissue to shrink
evenly and will result in a superior, wrinklefree
covering job. Tissue overlaps require a
second coat of dope on the overlapped
surface, to get the added tissue piece to
adhere properly.
After the tissue is stretched and dry,
brush it with a coat of nitrate that has
been thinned 50%. The red stripe on the
fuselage is a piece of red Esaki that is
applied with thinner and given a coat of
the 50/50 nitrate.
The blue fuselage bottom, wing
underside, top chevrons, and stabilizer
were airbrushed using the pigment from
Dark Blue Floquil model-train paint,
mixed into nitrate thinner and added to
clear nitrate dope. In the same manner,
the wing, stabilizer, and rudder LEs
were airbrushed with Old Silver Floquil.
Frisket paper was used to mask the
surfaces for all airbrushing.
I trimmed the canopy and attached it
to the finished model with Pacer
Formula 560 Canopy Glue. The spinner,
which I vacuum-formed from .030-inch
Vivak, was airbrushed on the inside with
chrome enamel, which is designed for
use on model-car bodies. I coated the
spinner with flat-black enamel, to give a
deep, polished look. I glued the spinner
to the propeller backplate with Formula
560.
I gave the propeller several coats of
clear nitrate mixed with talc to fill the
balsa grain. I airbrushed it with flatblack
enamel and then painted the tips
flat white.
I have vacuum-formed canopies,
spinners, and water-slide decals for the
Texan, as well as a tissue-covering DVD
for aeromodelers. I will also provide
assistance with questions concerning
construction details via e-mail. Please
preface all such correspondence with
“Texan II” in the subject line.
Flying: My Texan flew “off the board”
with little adjustment required. Remove
the propeller and add clay to the nose, to
get the CG correct. Test-glide the Texan
over high grass, by pointing it at a spot
close to 50 feet ahead and giving it a
firm toss toward that spot.
Cure diving or stalling with small
adjustments to the stabilizer decalage.
Cure unwanted turning/spiraling by
adding small bits of clay to the wingtip
opposite the turn.
When you are satisfied with the
glide, add the rubber motor (three loops
of 1/8-inch Tan Super Sport, 40 inches
long, braided). Recheck the CG and
wind in 450 turns. When released, the
model should climb and turn right; make
all adjustments by shimming the
thrustline.
As the airplane begins to behave, add
turns until you get to approximately
1,750. At this point, make sure that you
have binoculars available and a reliable
way to retrieve your model.
Good luck with your Texan II. MA
Bob Isaacks
[email protected]

RUBBER SCALE modelers are always in
search of the “perfect subject.” The modeled
airplane must be charismatic, well
documented, and, most important, possess
good areas and moments, to assure
successful flight performance. Additionally,
the aircraft must offer some promise of ease
of construction as the plans are developed.
The Raytheon/Beechcraft Texan II, a
turbo-powered trainer, is currently in use by
the US Air Force and meets all of the
requirements I mentioned. I live in Katy,
Texas, and own a ranch near Del Rio,
Texas, which is home of the 47th Flying
Training Wing at Laughlin Air Force Base.
Texan IIs are constantly in the air around
Del Rio, and I have spent several hours
watching the sleek trainers shoot approaches
and practice touch-and-gos at Laughlin.
I made contact with Captain Ken Hall,
chief of public affairs at Laughlin, and
Kent Cummings, chief of community and
media relations, who allowed me to take
photos of a Texan II on the flightline for
authentication of the model I’m
presenting in this article.
My thanks to the personnel at
Laughlin—especially Carl Riordan, T-6
maintenance work leader, and Mark
Escobar, aircraft sign painter—who were
very cooperative in helping me obtain some
details that are not currently available on
the Internet.
The Texan II is a development/redesign
of the Pilatus PC-9: a trainer that several
countries currently use. With slight
modifications to the fins and canopy
framing, the model in this feature can be
built as a PC-9. A Google search will yield
a myriad of mouthwatering PC-9 color
schemes that beg to be replicated on a
model.
While researching the Texan II, I found
references indicating that the Pilatus is a
direct descendant of the Arado Ar.96
German World War II trainer. My last
article published in MA, in the December
2005 issue, was about an Ar.96. The design
similarities are astonishing, and the Arado
was conceived in 1938.
CONSTRUCTION
A quick glance at the Texan II’s plans
reveal its low wing placement, which is
ideal for conversion to an RC electricpowered
park flyer. There is plenty of room
for miniature servos, and the rudder and
elevator surfaces can be hinged by simply
doubling their respective spars.
For rubber-power enthusiasts, the CG
Type: Scale rubber-powered FF
Skill level: Intermediate
Wingspan: 25.25 inches
Wing area: 120 square inches
Airfoil: Wing, modified Neelmeyer; stabilizer,
5% cambered
Length: 25 inches
Weight without rubber: 50 grams
Motor: Three loops of 1/8-inch Tan Super
Sport, 40 inches long, braided
Construction: Primarily balsa with 1/32
plywood reinforcement
Propeller: Hand-carved balsa with 1:11/4
pitch-to-diameter ratio
Finish: Esaki tissue, dope for color
Trim: Right/right
sits almost exactly halfway between the
model’s rear peg and nose—perfect for a
long motor. Let’s begin.
Fuselage: The fuselage build is based on the
conventional box/former method. All of the
components are constructed from 1/16 balsa
except for the nose blocks, so it will be
unnecessary to raid the piggy bank to
purchase several thicknesses of balsa.
Pin down and build one fuselage side on
top of the other, noting that all verticals on
the box are the same length. I made a stop
on a miter box and cut all the verticals at one
time.
Also notice that the rear peg support can
be cut at the same time as the 1/16 uprights.
The fuselage longerons are straight, except
for the rear of the top longeron. It can be
notched and “cracked” to match the
fuselage/rudder rear line.
After the sides are completed/separated,
pin them to the top view on the plans and
add the crosspieces in the cabin area. Use a
square to keep the sides square and vertical.
When the cement is dry on the
crosspieces, glue the tail and front
crosspieces in place, making sure that the
nose and tail are square and centered on the
plans. Add the remaining crosspieces, front
and rear, checking for squareness at each
station.
At this point, I spray the completed
structure with a mist of water while it is still
pinned. This relieves any built-in stresses in
the balsa construction and results in a true
fuselage. No bananas wanted here.
I should mention that the plans are
covered with waxed paper before any
construction commences.
When the stress-relieved structure is dry,
add the bottom formers, front to rear. As
shown on the plans, the formers are
purposely slightly oversize. I typically make
a copy of the formers on bond paper and use
rubber cement to attach the copies to the
appropriate thickness of balsa sheet.
After cutting the formers from the sheet,
I can easily peel off the paper copies. Slight
rubbing removes the rubber cement residue
from the balsa.
The oversize formers are centered on
each station. When dry, they are sanded to
blend perfectly with the fuselage sides and
each other.
I add the center stringer, making sure that
it is straight front to rear, and then I add the
remaining stringers, alternating from side to
side, measuring to assure symmetry. I use a
small Swiss File to notch the formers and
get a perfect fit for each stringer.
After the bottom stringers are in place
and dry, remove/unpin the fuselage from the
plans. Add the top formers in the same
manner as the bottom.
The cockpit flooring is made from
extremely light 1/32 balsa, applied crossgrained
to the box. Laminate the 1/8 balsa for
the nose block, and add it and the bottom
chin block to the fuselage.
Leave these components slightly
oversize, add the 1/32 plywood nose ring to
the front of the assembly, and carefully
sand/blend them to the fuselage. Use the
plans and photos to obtain the correct side
and top profile.
I drilled the initial undersized hole for
the nose plug using a router bit with a
Dremel tool. Then I finished/sized the hole
using a sandpaper-wrapped dowel.
The exhaust stacks are made from scrap
balsa that is as thick as the widest portion of
the exhaust. I made copies of the top view of
the exhausts on bond paper, rubbercemented
them to the scrap balsa, and
jigsawed them to shape.
Carve/sand away anything that does not
look like an exhaust stack. I employed a
Dremel cutter to hollow out the stacks’
interior.
The stacks are one of the features that
gives the Texan its look, so take time to
shape them correctly. I used a circle
template to inscribe a ring on the inner
portion of the exhaust, where it is attached
to the fuselage. By carving and sanding the
balsa to that circle, the exhaust stacks will
quickly take on the desired profile.
The spinner is made utilizing a Dremel
tool. Use scissors to cut a piece of 1/32
plywood slightly larger than 13/8 inches in
diameter. Mount this on a Dremel arbor (the
one used for holding abrasive discs) and
sand it to exactly 13/8 inches.
Add an oversized balsa block to the
plywood disc using Ambroid or Duco
cement. (You will have to rout out a small
recess in the center of the block, to clear the
arbor screw.) Give the glue plenty of time to
dry completely.
Rough-shape the spinner block with an
X-Acto knife before beginning to spin it up.
Use a sanding block and light pressure to
shape the spinner, comparing its profile to
the plans. You must wear eye protection for
the preceding operation!
The nose plug is made from laminated 1/8
sheet. I made an oversize lamination and
used it for both the nose block and the nose
plug.
The nose plug is made in the same
manner as the spinner. A plywood disk is
spun/sanded to size (3/4 inch). Glue the
oversized, laminated balsa plug to the disk
and spin it to size, while checking to ensure
that it is a good fit to the nose block. Fit a
13/8-inch-diameter 1/32 plywood disk to the
front of the plug and glue it.
Drill the nose plug on center at the front
with the other end of the plug resting on a
41/4° wedge. When rotated correctly, the
plug will yield the desired 3° of downthrust
and right thrust. Install a brass tubing
bushing with an ID to match the propellershaft
OD in the drilled hole, and the nose
plug is complete.
Wing: Make a rib template. I fabricated
mine from 1/16 plywood, by copying the root
rib on bond paper and rubber-cementing the
reproduction to the plywood. I jigsawed the
template and carefully sanded it to the exact
profile.
Drive two straight pins through the
template, letting them project 1/16 inch below
the bottom surface. Use CA to adhere the
pins in place and cut them off above the top
surface. These pins are used to hold the
template to the appropriate balsa
thicknesses, so you can carefully cut around
the template with an X-Acto knife.
I cut every rib using the same template. I
made smaller/shorter ribs by rotating it TEdown,
to achieve the length measured from
the plans. The point of rotation is the center
of the LE notch.
Pin down the TE along its entire length
and add the ribs, making sure that they are
square to the building board. Add the LE in
the fish-mouth front of the ribs and the
wingtips. When that assembly is dry,
remove it from the building board and sight
over the top of the ribs, to make sure that
there is a uniform taper from root to wingtip.
Use a long sanding block to remove high
spots in the upper camber of the wing. At
this point, I use a steel straightedge to mark
the spar locations, and I notch the ribs for
the spars with a small Swiss File.
Glue the spars in place except for the
bottom spar on the outer wing sections. To
ensure that washout (TE high at the
wingtips) is permanently built into the
structure, pin the LE down and raise the TE
using the wedge shown on the plans. Glue
the bottom spar in place and you are there.
Sand a bevel on the outer wing-panel LE,
TE, and spars, to allow for the 2-inch
dihedral on each panel. Glue the outer wing
panels in place, measuring to assure that an
equal amount of dihedral is in place. Add
the dihedral braces and gussets, give the
wing a final touch-up sanding, and you are
finished.
Tail Feathers: The tail surfaces are built in
a similar manner, with one exception. The
rudder is built with a symmetrical airfoil, so
it is necessary to shim the LE and TE off of
the building board before adding the ribs.
The stabilizer is flat-bottomed, so you can
pin all components directly to the board.
After gluing in the ribs, the stabilizer is
airfoiled (the top surface only is cambered)
while the rudder is airfoiled (cambered) on
both sides. Cut the stabilizer strakes and
rudder forward fin, sand the appropriate
edges, and the tail surfaces are ready to
cover.
Propeller: Carve the propeller by hand,
using the profile shown on the plans. Jigsaw
the top “bowtie” profile and drill a 3/32-inchdiameter
hole in the center. Jigsaw the side
profile.
Begin carving with the back of the
propeller, carefully moving across corners.
Go slowly and make sure that both of the
propeller’s undersides are carved to match. I
use a small balsa sanding block with a 5%
arc on its upper surface to sand in a slight
undercamber on the blades.
Carve a camber on the top surface, using
your fingers and feel to attain the same
thickness on both blades. Spin/sand a 13/8-
inch-diameter 1/32 plywood backplate, and
enlarge the center hole to 3/32 inch.
Install the propeller on the backplate,
using 3/32-inch-OD brass tubing to bush both
the backplate and the propeller. Install a
larger brass-tube “clutch” over the bushing,
and the propeller is ready for finishing.
Add the hollowed-out balsa spinner or a
vacuum-formed version after you finish the
propeller, backplate, nose plug, shaft, and
bearing assembly. See the sketch of these
components for reference purposes.
Finishing: The traditional nitrate dope-and-
Esaki tissue method was used to finish the
Texan. I prepared all surfaces by coating
every one that would contact the tissue with
several coats of nitrate dope, sanding after
the first coat. I applied enough dope so that
the surfaces would appear glossy.
I applied the white Esaki tissue wet,
using 70% alcohol as the wetting agent. I
used thinner, brushed through the tissue, to
apply it to the airframe.
It is important to apply the thinner only
to the periphery of the surface that is being
covered. This allows the wet tissue to shrink
evenly and will result in a superior, wrinklefree
covering job. Tissue overlaps require a
second coat of dope on the overlapped
surface, to get the added tissue piece to
adhere properly.
After the tissue is stretched and dry,
brush it with a coat of nitrate that has
been thinned 50%. The red stripe on the
fuselage is a piece of red Esaki that is
applied with thinner and given a coat of
the 50/50 nitrate.
The blue fuselage bottom, wing
underside, top chevrons, and stabilizer
were airbrushed using the pigment from
Dark Blue Floquil model-train paint,
mixed into nitrate thinner and added to
clear nitrate dope. In the same manner,
the wing, stabilizer, and rudder LEs
were airbrushed with Old Silver Floquil.
Frisket paper was used to mask the
surfaces for all airbrushing.
I trimmed the canopy and attached it
to the finished model with Pacer
Formula 560 Canopy Glue. The spinner,
which I vacuum-formed from .030-inch
Vivak, was airbrushed on the inside with
chrome enamel, which is designed for
use on model-car bodies. I coated the
spinner with flat-black enamel, to give a
deep, polished look. I glued the spinner
to the propeller backplate with Formula
560.
I gave the propeller several coats of
clear nitrate mixed with talc to fill the
balsa grain. I airbrushed it with flatblack
enamel and then painted the tips
flat white.
I have vacuum-formed canopies,
spinners, and water-slide decals for the
Texan, as well as a tissue-covering DVD
for aeromodelers. I will also provide
assistance with questions concerning
construction details via e-mail. Please
preface all such correspondence with
“Texan II” in the subject line.
Flying: My Texan flew “off the board”
with little adjustment required. Remove
the propeller and add clay to the nose, to
get the CG correct. Test-glide the Texan
over high grass, by pointing it at a spot
close to 50 feet ahead and giving it a
firm toss toward that spot.
Cure diving or stalling with small
adjustments to the stabilizer decalage.
Cure unwanted turning/spiraling by
adding small bits of clay to the wingtip
opposite the turn.
When you are satisfied with the
glide, add the rubber motor (three loops
of 1/8-inch Tan Super Sport, 40 inches
long, braided). Recheck the CG and
wind in 450 turns. When released, the
model should climb and turn right; make
all adjustments by shimming the
thrustline.
As the airplane begins to behave, add
turns until you get to approximately
1,750. At this point, make sure that you
have binoculars available and a reliable
way to retrieve your model.
Good luck with your Texan II. MA
Bob Isaacks
[email protected]