46 MODEL AVIATION
Left: Lawrence likes to sand the ribs well, to make them
uniform in size. He pays particular attention to the nose ribs
from the spars forward.
by Lawrence Klingberg
Full-scale construction
techniques pay off
The author
with his
Sopwith Pup
at the AMA
Convention
in Ontario
CA in 2004.
WHEN scratcH-buildiNg large-scale models, especially
of World War I through Golden Age of Aviation subjects, the
wings can be problematic. One of the main concerns is
fabricating the LEs; you can’t go to the hobby store and buy
07sig2_00MSTRPG.QXD 5/26/10 11:41 AM Page 46
The basic wing construction. You can see spars, webbing, and
holes for cardboard tubes, for additional strength. The tubes can
also be used for feeding wires out to servos for aileron control.
The 1/4 balsa nose pieces are installed between the ribs, and 1/4
balsa doublers are glued onto the ribs, to make an area nearly 3/4
inch wide for aluminum butt joints.
You can see the airfoil, TE, and cardboard tube. Aluminum tubes
go into the wing center-section. The rear spar is also shown with
wood gussets.
Rubber bands keep aluminum in place while 1/2-inch brads are nailed
at 3/4-inch intervals on the 1/2 x 1/2-inch spars. It takes several rubber
bands to make the aluminum conform to this shape.
Cardboard tubes are the same ones on which the covering is
rolled. Lawrence has been using them for spars and aileron
control-wire conduits for a long time. They are glued all the way
around with five-minute epoxy.
Aluminum tubes are used to join the wings and assist with
alignment, while adding strength. You can see the additional balsa
that is used for wing tank sheeting.
Photos by the author
July 2010 47
07sig2_00MSTRPG.QXD 5/26/10 10:05 AM Page 47
48 MODEL AVIATION
The completed wing is ready for covering. Coat the whole
airframe with three to four coats of Balsarite before applying
Solartex material.
Cover the wing bottom, and then bring the Solartex up and over
to the spar. Apply a second piece from the spar rearward. You can
see the plywood gas tank.
Left: This is how the partially covered center-section of the top
wing should look when you apply the Solartex. An access hatch is
located in the center.
The author’s Sikorsky S-35 at the 2009 AMA Expo in Ontario CA. It was the first
model on which he used aluminum LE construction, and it took first place in static
competition. The wing spans 17 feet and has a 21-inch chord, making it 1/6 scale.
balsa stock that is large enough for the job. Most of my airplanes
have wing chords of 16 to 25 inches, making the airfoil huge by
today’s standards.
Aeromodelers have used several techniques throughout the years
to solve this dilemma, and they include sheeting the LE with thin
balsa or plywood. Another method is to cut foam pieces, using the
hot-wire method, into the shapes your airplane needs and then to
glue them onto the spars.
I have used the preceding approaches, and I have recently
learned the best one to use to make LEs for my models. It’s to do it
07sig2_00MSTRPG.QXD 5/26/10 11:43 AM Page 48
50 MODEL AVIATION
in a way that EAA (Experimental Aircraft
Association) builders have done for years on
their ultralight aircraft.
That type of construction consists of using
aluminum sheeting over formers and creating
a light, smooth surface on which to put the
covering. The only restriction is that the wing
LE airfoil must be straight the whole length of
the wing.
Most WW I and all civilian airplanes of
the 1920s and 1930s fit into that category.
Some of those are the Fokker D.VII and Dr.I
triplane, Curtiss Robin, Bellanca, Boeing 80,
Sikorsky, and Curtiss Condor. These models
can incorporate the aluminum-wing
technique—a great way to build bigger and
better Scale airplanes.
I have constructed giant radio-controlled
aircraft for more than 30 years, many of
which I have built from scratch. Most are
historical subjects, ranging from 1910 through
the Golden Age of the late 1930s. My projects
range in size from 1/6 to 1/2 scale.
In the last couple of years I have run into
the problem of how to make LEs for wings on
a 17-foot-span Sikorsky S-35 and a 15-footspan
Curtiss Condor. The wings had identical
chords, at 21 inches, with a measurement of 3
inches at the thickest points.
I didn’t want to use foam for the LEs, as I
had done in the past, so the idea of aluminum
LEs was born. This method has worked out
very well for me, and I thought it might be of
interest to others who build similar-size
models.
But I have one word of caution: do not try
to use this method on small wings! Aluminum
doesn’t like to bend sharply around the LEs,
making the technique much more difficult.
The aluminum I have been using is 10
thousandths thick and is available from most
of The Home Depot stores. It comes in 20-
inch widths and is approximately 25 feet long.
Originally intended for the valleys on roofs,
this material is reasonably priced and easy to
purchase.
The wings are constructed with skinning
the LE in mind. All ribs are cut from 3/16 balsa
and must be made accurately; the sheet
aluminum is not too forgiving as it is formed
around the nose of the ribs.
The ribs are spaced at 2-inch intervals,
which equals 1 foot when building to 1/6 scale.
Shear webs, which are 1/8 plywood, are glued
between the ribs, against the two spars.
Wherever there is to be a joint in the LE,
glue 1/4-inch pieces of balsa onto the ribs to
provide extra support for the aluminum. Then
the width of the joint will be roughly 3/4 inch.
These additional doublers need to be in
place, because when aluminum is pulled
around the nose, it will buckle from the
pressure that the rubber bands put on it when
it is formed and nailed onto the spars. Then 1/4
balsa pieces need to be glued between the
nose ribs and sanded to shape.
After you construct the wings and are
ready to attach the aluminum, measure the
front-to-rear dimension and cut the sheet
approximately 10 x 20 inches. The material
will naturally want to bend the way it comes
off of the roll, so it must be cut that way.
Once the aluminum is cut to size, use a
fine marking pen to draw a line 1/4 inch in
from the edge, the length of the sheet. Mark
this line in 3/4-inch intervals so you can use an
automatic center punch to dimple the
aluminum before drilling the holes where
marked. Use a #60 drill to punch all the holes
along the edge.
The sheet is now ready to nail onto the 1/2
x 1/2-inch top spar. To do this, use 1/2-inch
small brads. Hold them with a pair of longnose
pliers to start them before tacking them
with a hammer.
It’s best to put the wing on a solid surface,
such as a piece of steel, when tacking. After
tacking the aluminum the full length of the
spar, you have arrived at the hard part of the
job.
Cut several 3/8 x 3/8-inch square white-pine
pieces approximately 6 inches long to use as
posts around which to put the rubber bands.
Those bands are used to put pressure on the
aluminum as it is formed around the nose ribs.
Place the rubber bands around the LE at 2-
inch intervals (the spacing of the ribs), so that
they are over each rib. If they are not at the rib
location, they can easily make a buckle in the
LE.
When putting on the rubber bands and
then removing them, be extremely careful; the
wood posts can be sent flying through the air
if they are not taken off cautiously.
Experience is a great teacher.
I use large #84 rubber bands that are 1/2 x
31/2 inches in size. After putting on two or
three and pulling down the LE to conform to
the rib shape, turn the wing over.
Make a line directly over the bottom 1/2 x
1/2-inch spar. Mark it off in 3/4-inch
increments, as you did on the top of the wing.
Once complete, center-punch the marks and
drill the holes for the brads to be nailed
through onto the spar.
Carefully remove all of the rubber bands
and posts, and you are left with the completed
LE. It usually takes me close to an hour to do
a 20-inch section of wing. Line up the next
piece of aluminum and keep going until the
wing is finished.
Covering the Wing: I have been using
Solartex to cover my models for more than 30
years, and I consider it to be the best material
for the job. Start by covering the nose section
from spar to spar, and then cover from the
spar rearward on both the top and bottom of
the wing.
After securing the material on the wing, I
put on Stits pinking tape, 1/2 inch wide, over
the seams and the wing ribs. I use the 4-inch
pinking tape to go the full length of the wing
over both the top and bottom spars.
The finishing touch is to put elongated
glue dots on the ribs that have the pinking tape
on them. Space the glue dots 3/4 inch apart, to
simulate the rib stitching on a full-scale
airplane.
At this point I spray the Solartex with
Rust-Oleum gray automotive primer. Then I
apply at least three or four coats of my choice
of color; I use Rust-Oleum in the spray cans
from The Home Depot. It has lasted for more
than 20 years and holds up well, even on my
seaplanes.
Good luck with your airplane. Build them
big, because they fly better! MA
Lawrence Klingberg
8111 Dartmoor Dr.
Huntington Beach CA 92646
Sources:
Solartex
www.solarfilm.co.uk
Rustoleum
(800) 323-3584
www.rustoleum.com
07sig2_00MSTRPG.QXD 5/26/10 10:10 AM Page 50
Edition: Model Aviation - 2010/07
Page Numbers: 46,47,48,50
Edition: Model Aviation - 2010/07
Page Numbers: 46,47,48,50
46 MODEL AVIATION
Left: Lawrence likes to sand the ribs well, to make them
uniform in size. He pays particular attention to the nose ribs
from the spars forward.
by Lawrence Klingberg
Full-scale construction
techniques pay off
The author
with his
Sopwith Pup
at the AMA
Convention
in Ontario
CA in 2004.
WHEN scratcH-buildiNg large-scale models, especially
of World War I through Golden Age of Aviation subjects, the
wings can be problematic. One of the main concerns is
fabricating the LEs; you can’t go to the hobby store and buy
07sig2_00MSTRPG.QXD 5/26/10 11:41 AM Page 46
The basic wing construction. You can see spars, webbing, and
holes for cardboard tubes, for additional strength. The tubes can
also be used for feeding wires out to servos for aileron control.
The 1/4 balsa nose pieces are installed between the ribs, and 1/4
balsa doublers are glued onto the ribs, to make an area nearly 3/4
inch wide for aluminum butt joints.
You can see the airfoil, TE, and cardboard tube. Aluminum tubes
go into the wing center-section. The rear spar is also shown with
wood gussets.
Rubber bands keep aluminum in place while 1/2-inch brads are nailed
at 3/4-inch intervals on the 1/2 x 1/2-inch spars. It takes several rubber
bands to make the aluminum conform to this shape.
Cardboard tubes are the same ones on which the covering is
rolled. Lawrence has been using them for spars and aileron
control-wire conduits for a long time. They are glued all the way
around with five-minute epoxy.
Aluminum tubes are used to join the wings and assist with
alignment, while adding strength. You can see the additional balsa
that is used for wing tank sheeting.
Photos by the author
July 2010 47
07sig2_00MSTRPG.QXD 5/26/10 10:05 AM Page 47
48 MODEL AVIATION
The completed wing is ready for covering. Coat the whole
airframe with three to four coats of Balsarite before applying
Solartex material.
Cover the wing bottom, and then bring the Solartex up and over
to the spar. Apply a second piece from the spar rearward. You can
see the plywood gas tank.
Left: This is how the partially covered center-section of the top
wing should look when you apply the Solartex. An access hatch is
located in the center.
The author’s Sikorsky S-35 at the 2009 AMA Expo in Ontario CA. It was the first
model on which he used aluminum LE construction, and it took first place in static
competition. The wing spans 17 feet and has a 21-inch chord, making it 1/6 scale.
balsa stock that is large enough for the job. Most of my airplanes
have wing chords of 16 to 25 inches, making the airfoil huge by
today’s standards.
Aeromodelers have used several techniques throughout the years
to solve this dilemma, and they include sheeting the LE with thin
balsa or plywood. Another method is to cut foam pieces, using the
hot-wire method, into the shapes your airplane needs and then to
glue them onto the spars.
I have used the preceding approaches, and I have recently
learned the best one to use to make LEs for my models. It’s to do it
07sig2_00MSTRPG.QXD 5/26/10 11:43 AM Page 48
50 MODEL AVIATION
in a way that EAA (Experimental Aircraft
Association) builders have done for years on
their ultralight aircraft.
That type of construction consists of using
aluminum sheeting over formers and creating
a light, smooth surface on which to put the
covering. The only restriction is that the wing
LE airfoil must be straight the whole length of
the wing.
Most WW I and all civilian airplanes of
the 1920s and 1930s fit into that category.
Some of those are the Fokker D.VII and Dr.I
triplane, Curtiss Robin, Bellanca, Boeing 80,
Sikorsky, and Curtiss Condor. These models
can incorporate the aluminum-wing
technique—a great way to build bigger and
better Scale airplanes.
I have constructed giant radio-controlled
aircraft for more than 30 years, many of
which I have built from scratch. Most are
historical subjects, ranging from 1910 through
the Golden Age of the late 1930s. My projects
range in size from 1/6 to 1/2 scale.
In the last couple of years I have run into
the problem of how to make LEs for wings on
a 17-foot-span Sikorsky S-35 and a 15-footspan
Curtiss Condor. The wings had identical
chords, at 21 inches, with a measurement of 3
inches at the thickest points.
I didn’t want to use foam for the LEs, as I
had done in the past, so the idea of aluminum
LEs was born. This method has worked out
very well for me, and I thought it might be of
interest to others who build similar-size
models.
But I have one word of caution: do not try
to use this method on small wings! Aluminum
doesn’t like to bend sharply around the LEs,
making the technique much more difficult.
The aluminum I have been using is 10
thousandths thick and is available from most
of The Home Depot stores. It comes in 20-
inch widths and is approximately 25 feet long.
Originally intended for the valleys on roofs,
this material is reasonably priced and easy to
purchase.
The wings are constructed with skinning
the LE in mind. All ribs are cut from 3/16 balsa
and must be made accurately; the sheet
aluminum is not too forgiving as it is formed
around the nose of the ribs.
The ribs are spaced at 2-inch intervals,
which equals 1 foot when building to 1/6 scale.
Shear webs, which are 1/8 plywood, are glued
between the ribs, against the two spars.
Wherever there is to be a joint in the LE,
glue 1/4-inch pieces of balsa onto the ribs to
provide extra support for the aluminum. Then
the width of the joint will be roughly 3/4 inch.
These additional doublers need to be in
place, because when aluminum is pulled
around the nose, it will buckle from the
pressure that the rubber bands put on it when
it is formed and nailed onto the spars. Then 1/4
balsa pieces need to be glued between the
nose ribs and sanded to shape.
After you construct the wings and are
ready to attach the aluminum, measure the
front-to-rear dimension and cut the sheet
approximately 10 x 20 inches. The material
will naturally want to bend the way it comes
off of the roll, so it must be cut that way.
Once the aluminum is cut to size, use a
fine marking pen to draw a line 1/4 inch in
from the edge, the length of the sheet. Mark
this line in 3/4-inch intervals so you can use an
automatic center punch to dimple the
aluminum before drilling the holes where
marked. Use a #60 drill to punch all the holes
along the edge.
The sheet is now ready to nail onto the 1/2
x 1/2-inch top spar. To do this, use 1/2-inch
small brads. Hold them with a pair of longnose
pliers to start them before tacking them
with a hammer.
It’s best to put the wing on a solid surface,
such as a piece of steel, when tacking. After
tacking the aluminum the full length of the
spar, you have arrived at the hard part of the
job.
Cut several 3/8 x 3/8-inch square white-pine
pieces approximately 6 inches long to use as
posts around which to put the rubber bands.
Those bands are used to put pressure on the
aluminum as it is formed around the nose ribs.
Place the rubber bands around the LE at 2-
inch intervals (the spacing of the ribs), so that
they are over each rib. If they are not at the rib
location, they can easily make a buckle in the
LE.
When putting on the rubber bands and
then removing them, be extremely careful; the
wood posts can be sent flying through the air
if they are not taken off cautiously.
Experience is a great teacher.
I use large #84 rubber bands that are 1/2 x
31/2 inches in size. After putting on two or
three and pulling down the LE to conform to
the rib shape, turn the wing over.
Make a line directly over the bottom 1/2 x
1/2-inch spar. Mark it off in 3/4-inch
increments, as you did on the top of the wing.
Once complete, center-punch the marks and
drill the holes for the brads to be nailed
through onto the spar.
Carefully remove all of the rubber bands
and posts, and you are left with the completed
LE. It usually takes me close to an hour to do
a 20-inch section of wing. Line up the next
piece of aluminum and keep going until the
wing is finished.
Covering the Wing: I have been using
Solartex to cover my models for more than 30
years, and I consider it to be the best material
for the job. Start by covering the nose section
from spar to spar, and then cover from the
spar rearward on both the top and bottom of
the wing.
After securing the material on the wing, I
put on Stits pinking tape, 1/2 inch wide, over
the seams and the wing ribs. I use the 4-inch
pinking tape to go the full length of the wing
over both the top and bottom spars.
The finishing touch is to put elongated
glue dots on the ribs that have the pinking tape
on them. Space the glue dots 3/4 inch apart, to
simulate the rib stitching on a full-scale
airplane.
At this point I spray the Solartex with
Rust-Oleum gray automotive primer. Then I
apply at least three or four coats of my choice
of color; I use Rust-Oleum in the spray cans
from The Home Depot. It has lasted for more
than 20 years and holds up well, even on my
seaplanes.
Good luck with your airplane. Build them
big, because they fly better! MA
Lawrence Klingberg
8111 Dartmoor Dr.
Huntington Beach CA 92646
Sources:
Solartex
www.solarfilm.co.uk
Rustoleum
(800) 323-3584
www.rustoleum.com
07sig2_00MSTRPG.QXD 5/26/10 10:10 AM Page 50
Edition: Model Aviation - 2010/07
Page Numbers: 46,47,48,50
46 MODEL AVIATION
Left: Lawrence likes to sand the ribs well, to make them
uniform in size. He pays particular attention to the nose ribs
from the spars forward.
by Lawrence Klingberg
Full-scale construction
techniques pay off
The author
with his
Sopwith Pup
at the AMA
Convention
in Ontario
CA in 2004.
WHEN scratcH-buildiNg large-scale models, especially
of World War I through Golden Age of Aviation subjects, the
wings can be problematic. One of the main concerns is
fabricating the LEs; you can’t go to the hobby store and buy
07sig2_00MSTRPG.QXD 5/26/10 11:41 AM Page 46
The basic wing construction. You can see spars, webbing, and
holes for cardboard tubes, for additional strength. The tubes can
also be used for feeding wires out to servos for aileron control.
The 1/4 balsa nose pieces are installed between the ribs, and 1/4
balsa doublers are glued onto the ribs, to make an area nearly 3/4
inch wide for aluminum butt joints.
You can see the airfoil, TE, and cardboard tube. Aluminum tubes
go into the wing center-section. The rear spar is also shown with
wood gussets.
Rubber bands keep aluminum in place while 1/2-inch brads are nailed
at 3/4-inch intervals on the 1/2 x 1/2-inch spars. It takes several rubber
bands to make the aluminum conform to this shape.
Cardboard tubes are the same ones on which the covering is
rolled. Lawrence has been using them for spars and aileron
control-wire conduits for a long time. They are glued all the way
around with five-minute epoxy.
Aluminum tubes are used to join the wings and assist with
alignment, while adding strength. You can see the additional balsa
that is used for wing tank sheeting.
Photos by the author
July 2010 47
07sig2_00MSTRPG.QXD 5/26/10 10:05 AM Page 47
48 MODEL AVIATION
The completed wing is ready for covering. Coat the whole
airframe with three to four coats of Balsarite before applying
Solartex material.
Cover the wing bottom, and then bring the Solartex up and over
to the spar. Apply a second piece from the spar rearward. You can
see the plywood gas tank.
Left: This is how the partially covered center-section of the top
wing should look when you apply the Solartex. An access hatch is
located in the center.
The author’s Sikorsky S-35 at the 2009 AMA Expo in Ontario CA. It was the first
model on which he used aluminum LE construction, and it took first place in static
competition. The wing spans 17 feet and has a 21-inch chord, making it 1/6 scale.
balsa stock that is large enough for the job. Most of my airplanes
have wing chords of 16 to 25 inches, making the airfoil huge by
today’s standards.
Aeromodelers have used several techniques throughout the years
to solve this dilemma, and they include sheeting the LE with thin
balsa or plywood. Another method is to cut foam pieces, using the
hot-wire method, into the shapes your airplane needs and then to
glue them onto the spars.
I have used the preceding approaches, and I have recently
learned the best one to use to make LEs for my models. It’s to do it
07sig2_00MSTRPG.QXD 5/26/10 11:43 AM Page 48
50 MODEL AVIATION
in a way that EAA (Experimental Aircraft
Association) builders have done for years on
their ultralight aircraft.
That type of construction consists of using
aluminum sheeting over formers and creating
a light, smooth surface on which to put the
covering. The only restriction is that the wing
LE airfoil must be straight the whole length of
the wing.
Most WW I and all civilian airplanes of
the 1920s and 1930s fit into that category.
Some of those are the Fokker D.VII and Dr.I
triplane, Curtiss Robin, Bellanca, Boeing 80,
Sikorsky, and Curtiss Condor. These models
can incorporate the aluminum-wing
technique—a great way to build bigger and
better Scale airplanes.
I have constructed giant radio-controlled
aircraft for more than 30 years, many of
which I have built from scratch. Most are
historical subjects, ranging from 1910 through
the Golden Age of the late 1930s. My projects
range in size from 1/6 to 1/2 scale.
In the last couple of years I have run into
the problem of how to make LEs for wings on
a 17-foot-span Sikorsky S-35 and a 15-footspan
Curtiss Condor. The wings had identical
chords, at 21 inches, with a measurement of 3
inches at the thickest points.
I didn’t want to use foam for the LEs, as I
had done in the past, so the idea of aluminum
LEs was born. This method has worked out
very well for me, and I thought it might be of
interest to others who build similar-size
models.
But I have one word of caution: do not try
to use this method on small wings! Aluminum
doesn’t like to bend sharply around the LEs,
making the technique much more difficult.
The aluminum I have been using is 10
thousandths thick and is available from most
of The Home Depot stores. It comes in 20-
inch widths and is approximately 25 feet long.
Originally intended for the valleys on roofs,
this material is reasonably priced and easy to
purchase.
The wings are constructed with skinning
the LE in mind. All ribs are cut from 3/16 balsa
and must be made accurately; the sheet
aluminum is not too forgiving as it is formed
around the nose of the ribs.
The ribs are spaced at 2-inch intervals,
which equals 1 foot when building to 1/6 scale.
Shear webs, which are 1/8 plywood, are glued
between the ribs, against the two spars.
Wherever there is to be a joint in the LE,
glue 1/4-inch pieces of balsa onto the ribs to
provide extra support for the aluminum. Then
the width of the joint will be roughly 3/4 inch.
These additional doublers need to be in
place, because when aluminum is pulled
around the nose, it will buckle from the
pressure that the rubber bands put on it when
it is formed and nailed onto the spars. Then 1/4
balsa pieces need to be glued between the
nose ribs and sanded to shape.
After you construct the wings and are
ready to attach the aluminum, measure the
front-to-rear dimension and cut the sheet
approximately 10 x 20 inches. The material
will naturally want to bend the way it comes
off of the roll, so it must be cut that way.
Once the aluminum is cut to size, use a
fine marking pen to draw a line 1/4 inch in
from the edge, the length of the sheet. Mark
this line in 3/4-inch intervals so you can use an
automatic center punch to dimple the
aluminum before drilling the holes where
marked. Use a #60 drill to punch all the holes
along the edge.
The sheet is now ready to nail onto the 1/2
x 1/2-inch top spar. To do this, use 1/2-inch
small brads. Hold them with a pair of longnose
pliers to start them before tacking them
with a hammer.
It’s best to put the wing on a solid surface,
such as a piece of steel, when tacking. After
tacking the aluminum the full length of the
spar, you have arrived at the hard part of the
job.
Cut several 3/8 x 3/8-inch square white-pine
pieces approximately 6 inches long to use as
posts around which to put the rubber bands.
Those bands are used to put pressure on the
aluminum as it is formed around the nose ribs.
Place the rubber bands around the LE at 2-
inch intervals (the spacing of the ribs), so that
they are over each rib. If they are not at the rib
location, they can easily make a buckle in the
LE.
When putting on the rubber bands and
then removing them, be extremely careful; the
wood posts can be sent flying through the air
if they are not taken off cautiously.
Experience is a great teacher.
I use large #84 rubber bands that are 1/2 x
31/2 inches in size. After putting on two or
three and pulling down the LE to conform to
the rib shape, turn the wing over.
Make a line directly over the bottom 1/2 x
1/2-inch spar. Mark it off in 3/4-inch
increments, as you did on the top of the wing.
Once complete, center-punch the marks and
drill the holes for the brads to be nailed
through onto the spar.
Carefully remove all of the rubber bands
and posts, and you are left with the completed
LE. It usually takes me close to an hour to do
a 20-inch section of wing. Line up the next
piece of aluminum and keep going until the
wing is finished.
Covering the Wing: I have been using
Solartex to cover my models for more than 30
years, and I consider it to be the best material
for the job. Start by covering the nose section
from spar to spar, and then cover from the
spar rearward on both the top and bottom of
the wing.
After securing the material on the wing, I
put on Stits pinking tape, 1/2 inch wide, over
the seams and the wing ribs. I use the 4-inch
pinking tape to go the full length of the wing
over both the top and bottom spars.
The finishing touch is to put elongated
glue dots on the ribs that have the pinking tape
on them. Space the glue dots 3/4 inch apart, to
simulate the rib stitching on a full-scale
airplane.
At this point I spray the Solartex with
Rust-Oleum gray automotive primer. Then I
apply at least three or four coats of my choice
of color; I use Rust-Oleum in the spray cans
from The Home Depot. It has lasted for more
than 20 years and holds up well, even on my
seaplanes.
Good luck with your airplane. Build them
big, because they fly better! MA
Lawrence Klingberg
8111 Dartmoor Dr.
Huntington Beach CA 92646
Sources:
Solartex
www.solarfilm.co.uk
Rustoleum
(800) 323-3584
www.rustoleum.com
07sig2_00MSTRPG.QXD 5/26/10 10:10 AM Page 50
Edition: Model Aviation - 2010/07
Page Numbers: 46,47,48,50
46 MODEL AVIATION
Left: Lawrence likes to sand the ribs well, to make them
uniform in size. He pays particular attention to the nose ribs
from the spars forward.
by Lawrence Klingberg
Full-scale construction
techniques pay off
The author
with his
Sopwith Pup
at the AMA
Convention
in Ontario
CA in 2004.
WHEN scratcH-buildiNg large-scale models, especially
of World War I through Golden Age of Aviation subjects, the
wings can be problematic. One of the main concerns is
fabricating the LEs; you can’t go to the hobby store and buy
07sig2_00MSTRPG.QXD 5/26/10 11:41 AM Page 46
The basic wing construction. You can see spars, webbing, and
holes for cardboard tubes, for additional strength. The tubes can
also be used for feeding wires out to servos for aileron control.
The 1/4 balsa nose pieces are installed between the ribs, and 1/4
balsa doublers are glued onto the ribs, to make an area nearly 3/4
inch wide for aluminum butt joints.
You can see the airfoil, TE, and cardboard tube. Aluminum tubes
go into the wing center-section. The rear spar is also shown with
wood gussets.
Rubber bands keep aluminum in place while 1/2-inch brads are nailed
at 3/4-inch intervals on the 1/2 x 1/2-inch spars. It takes several rubber
bands to make the aluminum conform to this shape.
Cardboard tubes are the same ones on which the covering is
rolled. Lawrence has been using them for spars and aileron
control-wire conduits for a long time. They are glued all the way
around with five-minute epoxy.
Aluminum tubes are used to join the wings and assist with
alignment, while adding strength. You can see the additional balsa
that is used for wing tank sheeting.
Photos by the author
July 2010 47
07sig2_00MSTRPG.QXD 5/26/10 10:05 AM Page 47
48 MODEL AVIATION
The completed wing is ready for covering. Coat the whole
airframe with three to four coats of Balsarite before applying
Solartex material.
Cover the wing bottom, and then bring the Solartex up and over
to the spar. Apply a second piece from the spar rearward. You can
see the plywood gas tank.
Left: This is how the partially covered center-section of the top
wing should look when you apply the Solartex. An access hatch is
located in the center.
The author’s Sikorsky S-35 at the 2009 AMA Expo in Ontario CA. It was the first
model on which he used aluminum LE construction, and it took first place in static
competition. The wing spans 17 feet and has a 21-inch chord, making it 1/6 scale.
balsa stock that is large enough for the job. Most of my airplanes
have wing chords of 16 to 25 inches, making the airfoil huge by
today’s standards.
Aeromodelers have used several techniques throughout the years
to solve this dilemma, and they include sheeting the LE with thin
balsa or plywood. Another method is to cut foam pieces, using the
hot-wire method, into the shapes your airplane needs and then to
glue them onto the spars.
I have used the preceding approaches, and I have recently
learned the best one to use to make LEs for my models. It’s to do it
07sig2_00MSTRPG.QXD 5/26/10 11:43 AM Page 48
50 MODEL AVIATION
in a way that EAA (Experimental Aircraft
Association) builders have done for years on
their ultralight aircraft.
That type of construction consists of using
aluminum sheeting over formers and creating
a light, smooth surface on which to put the
covering. The only restriction is that the wing
LE airfoil must be straight the whole length of
the wing.
Most WW I and all civilian airplanes of
the 1920s and 1930s fit into that category.
Some of those are the Fokker D.VII and Dr.I
triplane, Curtiss Robin, Bellanca, Boeing 80,
Sikorsky, and Curtiss Condor. These models
can incorporate the aluminum-wing
technique—a great way to build bigger and
better Scale airplanes.
I have constructed giant radio-controlled
aircraft for more than 30 years, many of
which I have built from scratch. Most are
historical subjects, ranging from 1910 through
the Golden Age of the late 1930s. My projects
range in size from 1/6 to 1/2 scale.
In the last couple of years I have run into
the problem of how to make LEs for wings on
a 17-foot-span Sikorsky S-35 and a 15-footspan
Curtiss Condor. The wings had identical
chords, at 21 inches, with a measurement of 3
inches at the thickest points.
I didn’t want to use foam for the LEs, as I
had done in the past, so the idea of aluminum
LEs was born. This method has worked out
very well for me, and I thought it might be of
interest to others who build similar-size
models.
But I have one word of caution: do not try
to use this method on small wings! Aluminum
doesn’t like to bend sharply around the LEs,
making the technique much more difficult.
The aluminum I have been using is 10
thousandths thick and is available from most
of The Home Depot stores. It comes in 20-
inch widths and is approximately 25 feet long.
Originally intended for the valleys on roofs,
this material is reasonably priced and easy to
purchase.
The wings are constructed with skinning
the LE in mind. All ribs are cut from 3/16 balsa
and must be made accurately; the sheet
aluminum is not too forgiving as it is formed
around the nose of the ribs.
The ribs are spaced at 2-inch intervals,
which equals 1 foot when building to 1/6 scale.
Shear webs, which are 1/8 plywood, are glued
between the ribs, against the two spars.
Wherever there is to be a joint in the LE,
glue 1/4-inch pieces of balsa onto the ribs to
provide extra support for the aluminum. Then
the width of the joint will be roughly 3/4 inch.
These additional doublers need to be in
place, because when aluminum is pulled
around the nose, it will buckle from the
pressure that the rubber bands put on it when
it is formed and nailed onto the spars. Then 1/4
balsa pieces need to be glued between the
nose ribs and sanded to shape.
After you construct the wings and are
ready to attach the aluminum, measure the
front-to-rear dimension and cut the sheet
approximately 10 x 20 inches. The material
will naturally want to bend the way it comes
off of the roll, so it must be cut that way.
Once the aluminum is cut to size, use a
fine marking pen to draw a line 1/4 inch in
from the edge, the length of the sheet. Mark
this line in 3/4-inch intervals so you can use an
automatic center punch to dimple the
aluminum before drilling the holes where
marked. Use a #60 drill to punch all the holes
along the edge.
The sheet is now ready to nail onto the 1/2
x 1/2-inch top spar. To do this, use 1/2-inch
small brads. Hold them with a pair of longnose
pliers to start them before tacking them
with a hammer.
It’s best to put the wing on a solid surface,
such as a piece of steel, when tacking. After
tacking the aluminum the full length of the
spar, you have arrived at the hard part of the
job.
Cut several 3/8 x 3/8-inch square white-pine
pieces approximately 6 inches long to use as
posts around which to put the rubber bands.
Those bands are used to put pressure on the
aluminum as it is formed around the nose ribs.
Place the rubber bands around the LE at 2-
inch intervals (the spacing of the ribs), so that
they are over each rib. If they are not at the rib
location, they can easily make a buckle in the
LE.
When putting on the rubber bands and
then removing them, be extremely careful; the
wood posts can be sent flying through the air
if they are not taken off cautiously.
Experience is a great teacher.
I use large #84 rubber bands that are 1/2 x
31/2 inches in size. After putting on two or
three and pulling down the LE to conform to
the rib shape, turn the wing over.
Make a line directly over the bottom 1/2 x
1/2-inch spar. Mark it off in 3/4-inch
increments, as you did on the top of the wing.
Once complete, center-punch the marks and
drill the holes for the brads to be nailed
through onto the spar.
Carefully remove all of the rubber bands
and posts, and you are left with the completed
LE. It usually takes me close to an hour to do
a 20-inch section of wing. Line up the next
piece of aluminum and keep going until the
wing is finished.
Covering the Wing: I have been using
Solartex to cover my models for more than 30
years, and I consider it to be the best material
for the job. Start by covering the nose section
from spar to spar, and then cover from the
spar rearward on both the top and bottom of
the wing.
After securing the material on the wing, I
put on Stits pinking tape, 1/2 inch wide, over
the seams and the wing ribs. I use the 4-inch
pinking tape to go the full length of the wing
over both the top and bottom spars.
The finishing touch is to put elongated
glue dots on the ribs that have the pinking tape
on them. Space the glue dots 3/4 inch apart, to
simulate the rib stitching on a full-scale
airplane.
At this point I spray the Solartex with
Rust-Oleum gray automotive primer. Then I
apply at least three or four coats of my choice
of color; I use Rust-Oleum in the spray cans
from The Home Depot. It has lasted for more
than 20 years and holds up well, even on my
seaplanes.
Good luck with your airplane. Build them
big, because they fly better! MA
Lawrence Klingberg
8111 Dartmoor Dr.
Huntington Beach CA 92646
Sources:
Solartex
www.solarfilm.co.uk
Rustoleum
(800) 323-3584
www.rustoleum.com
07sig2_00MSTRPG.QXD 5/26/10 10:10 AM Page 50
