ff DURATION - 2012/05

112 Model Aviation May 2012 www.ModelAviation.com
off, Gina placed
second behind
a flier with 30-
plus years of
experience—her
father, Andrew.
The Junior
Team Committee,
consisting of Jim
Parker, Charlie
Jones, Tom Vaccaro, and George Batiuk,
is raising funds to help defray some of
the team’s expenses. AMA covers travel,
lodging, and entry fees, but extra support
is needed.
In February, the Junior Committee
raffled off one of the late Bob White’s
Wakefields, model number 23, which
was the backup model when Bob won
the World Championship in 1987. Bob’s
winning model, number 22, is on display
in the National Model Aviation Museum
in Muncie, Indiana.
Also raffled off was a quilt depicting
all of the previous Junior World
Championships sites made by Charlie
Jones’ mother. Donations can be made
by check to AMA and should be
earmarked for the Junior Free Flight
Team. You can also send a check directly
ff DURATION
T he 2012 FAI Junior World Championships for Free Flight Model Aircraft
will be held July 27 through August 3 near Ljubljana, Slovenia. The United
States will be represented by Gina Barron, Logan Tetrick, and Michelle
Barron in F1A Towline Glider; Sevak Malkhasyan, Brian Pacelli, and Peyton
Tetrick in F1B Wakefield Rubber; and Taron Malkhasyan and Brian Pacelli in F1P
Power. As of early February, the third
slot in F1P had not been filled.
Once again, Brian Pacelli will do
double duty, flying Wakefield and
F1P Power. This year’s team includes
a set of brothers, Sevak and Taron
Malkhasyan; brother and sister, Logan
and Peyton Tetrick; and sisters, Gina
and Michelle Barron. George Batiuk
will be team manager.
Gina, who will turn 10 during the
Junior World Championships, will
be one of the youngest contestants
to represent the US in any World
Championships. Although her F1A
Towline gliders may span twice her
height, she handles them with skill.
At a contest last fall in Seguin, Texas,
Gina picked her own air for all seven
rounds and was one of two contestants
to max out; both fliers maxed the
first fly-off round. In the second fly-
FF Junior World Champs
by Louis Joyner
[email protected]
PLUS:
> America Cup
> National Cup
> Two-piece wings
> StarLink FliteTech
models
Brian Pacelli, who will fly F1B and F1P in this year’s
Junior FF World Championships, winds the rubber
outside of the model. This allows for a quicker
change in case of a blown motor.
Peyton Tetrick made the F1B team
flying a Vivchar model; her brother,
Logan, made the team in F1A
Towline Glider.
Taron Malkhasyan made the Junior team
flying F1P Power. He was also high-scoring
Junior in F1J and F1P in the America’s Cup.
114 Model Aviation May 2012 www.ModelAviation.com
ff duration
Below: Michelle Barron and her sister, Gina, comprise
two-thirds of the Junior F1A team attending the World
Championships in Slovenia.
Left: StarLink-FliteTech Models offers a variety
of models, kits, and accessories, including this
replacement shaft and three-part bobbin used
to update the front end of Burdov F1G Coupe
models.
Taron’s brother, Sevak Malkhasyan,
made the Junior team in F1B, earned
top points in the National Cup Junior
category, and was high Junior in F1B in
the America’s Cup.
to team manager George Batiuk, 576
Dana St., San Luis Obispo CA 93401.
America’s Cup
The annual multi-contest
competition for all of the FAI FF
events concluded this December. Here
are the results:
F1A Towline Glider: Brian Van Nest
(Gina Barron, high Junior)
F1B Wakefield Rubber: Blake Jensen
(Sevak Malkhasyan, high Junior)
F1C: Faust Parker
F1G Coupe Rubber: Blake Jensen
(Troy Davis, high Junior)
F1H Towline Glider: Mike McKeever
(Gina Barron, high Junior)
F1J Power: Faust Parker (Taron
Malkhasyan, high Junior and 4th place
overall)
F1P Power: Glen Schneider (Taron
Malkhasyan, high Junior and tied for
3rd place overall)
F1Q Electric: John Oldenkamp
F1E Slope Soaring: Peter Brocks
The America’s Cup, which was
created by the Southern California
Aero Team and is administered by Jim
Parker, offers a multi-contest format
that encourages modelers from the
United States, Canada, and Mexico,
to compete in FAI FF events. Points
are awarded at each contest, with a
first place receiving 25, second place
receiving 20, third place receiving 15,
fourth place receiving 10, and fifth
place receiving 5 points.
Additional points are awarded
depending on the number of
contestants flying in the event. Best
results from four contests are counted.
To encourage travel, only two contests
at any one site can be counted; the
other two results must be from two
other sites. In the case of a tie, results
from more contests are counted.
Detailed rules for the America’s Cup
can be found on the National Free
Flight Society (NFFS) website.
National Cup
The National Cup was created in
2003 to encourage participants to
travel and compete at FF contests
across the country. As is the America’s
Cup, the National Cup is a multicontest
competition. However, the
National Cup focuses on AMA FF
events.
Contestants in each of seven
categories accumulate points in the
individual events within that category
at contests across the country. To score
points, contestants must place in the
top five in an event. The highest six
scores in each event are counted.
To make it truly a nationwide cup,
no more than two scores are counted
from any single location. A seventh
score can be added by placing at one
of four exempt contests in each of the
four NFFS regions. The contests are the
Southwest Regionals in Eloy, Arizona;
the AMA Nats in Muncie, Indiana;
the Rocky Mountain Championships
in Denver, Colorado; and the King
Orange Internationals in Palm Bay,
Florida. A third score from one of the
exempt contests is to be counted.
In 2011, there were 81 contests with
615 contestants posting scores in 1,762
individual events. The categories and
the 2011 winners are:
AMA Power: Bob Hanford
Classic Power: Bob Hanford
Nostalgia Power (small): Bob Hanford
Nostalgia Power (large): Bob Hanford
AMA Rubber: Earl Griffith
Nostalgia Rubber: Don DeLoach
Glider: Tim Batiuk
Bob Hanford won all four of the
Power categories.
The National Cup includes a Junior
category, which combines scores from
selected Rubber, Power, and Glider
events. Sevak Malkhasyan topped this
category, with Tyler Moore in second,
only 14 points behind. Samuel Smetzer
was third, Taron Malkhasyan came in
fourth, and Elliot Plantner placed fifth.
Rules, detailed scores, and the 2012
National Cup contest schedule can be
found on the NFFS website.
Two-Piece Wings
Fifty years ago, one-piece wings were
the rule, even for large FF models.
In those days, before minivans and
SUVs, large wings were often strapped,
upside down, to the headliner of the
family sedan for transport to the flying
field. Today, many models use twopiece
wings that allow more compact
storage—often in a purpose-made
model box that safely stores several
complete models for a car trip or an
international flight.
Two-piece wings allow easy
adjustment of the relative incidence
between the two wing halves
as a trimming aid. This can be
accomplished by shimming underneath
the TE on a two-piece wing, rubber
banded to a traditional pylon or rail
system on the fuselage. The two wing
halves can also be connected by a
single wire running through the pylon
or fuselage; often one half is located by
a fixed rear pin and the other half with
an adjustable pin.
The adjustable pin can be linked to a
timer, either through a line or a servo,
to change the incidence of the wing
half at a predetermined time during
the flight. Known as a wing wiggler,
its use is nearly universal in the larger
FAI classes of F1A Towline Glider, F1B
Wakefield Rubber, and F1C Power,
usually coupled with auto rudder and
auto stabilizer.
For smaller models, such as an F1G
Coupe d’Hiver, a wing wiggler can even
be used as the only auto surface. On
my Coupes, I use a simple wing wiggler
made from wire and tubing to control
the left wing. At launch, the left panel
is set at several degrees negative relative
to the right wing half. This provides a
left rolling tendency during the initial
burst.
After 5 to 7 seconds, a timer releases
a line, allowing the left TE to move
down to the glide position. The result
is a straight, near-vertical initial climb,
transitioning into a right cruise and
right glide. No other auto surfaces
are used. (Photographs and a detailed
description of this wing wiggler can
be found in MA’s November 2010 “FF
Duration” column.)
A two-piece wing requires slightly
more effort during construction, but
the convenience of adjusting the wing
halves independently, as well as the
compactness, make it worth the effort.
Two-piece wings are often heavier
than a one-piece wing. The wing wire,
sockets in the two wing halves, and the
socket and additional reinforcing in the
pylon or fuselage, all add weight; this
is partially offset by eliminating the
center section reinforcements needed
with a one-piece wing.
The wing wire is often the main
offender concerning weight. In the past,
steel wire has been the most popular
choice. Typical diameters range from
3.0mm (slightly less than 1/8 inch) for
F1B, to 5.5mm to 6.0mm (less than 1/4
inch) for F1A and F1C. Steel wire can
also bend during a hard towline launch
or on DT.
Carbon fiber has been tried as a
lighter-weight alternative. The weight
saving can be significant. On his
F1B models, Paul Crowley has tried
substituting 1/8-inch diameter carbonfiber
rod for 1/8-inch steel wing wires.
“The weight saving was nice; 1 gram
for carbon versus 4 grams for steel,” he
said.
But there were problems. “I found
that the carbon-fiber rods would break
after repeated use, usually on launch,”
said Paul. “But the break was actually
promoted by hard DT landings. I
believe that the shear load at the pylon
was the cause; rounding the corners of
the holes didn’t help. The carbon-fiber
rod is a bundle of strands and you start
breaking them one at a time until the
strands that are left can’t take the stress
of a hard launch or DT.”
A solution is to protect the carbon
fiber with steel. One method is to
use thin-wall stainless steel tubing of
the desired diameter and fill it with
carbon-fiber tow wetted out with
epoxy. This can be done by inserting a
loop of Kevlar thread through a length
of steel tubing, then using the Kevlar
thread to pull a bundle of doubled
lengths of epoxy-soaked carbon-fiber
tow back through the tube.
For lighter models, such as F1G
Coupe and other Rubber models,
carbon-fiber rods or tubes still offer the
best weight-to-strength option for wing
wires. The popular Burdov Candy G
Coupe uses a purpose-made 4.5mmdiameter
carbon tube; carbon-tube
pultrusions, available from A2Z Corp
and CST, are offered in 3mm, 4mm,
and 5mm, which would be suitable for
many smaller, lightly-loaded models. (I
have had no problems using the 4.0mm
pultrusion for the wing wire on my
Coupes.) To avoid problems, frequently
inspect and replace carbon wing rods
or tubes.
Whatever you use for the wing wire,
it must fit properly into sockets in the
wings. Standard piano wire and the
next larger size aluminum tubing fits
too loosely. Aluminum tubing from
K&S has a wall thickness of 0.014 inch.
If you use 5/32-inch OD aluminum
tubing, the ID will be 0.12825; that’s
0.00325 inch bigger than 1/8-inch
piano wire. Not quite sloppy, but
loose enough to potentially cause trim
problems.
How do you get a perfect fit? One
solution is to make your own wing
sockets using a carbon-fiber sock. The
sock (available from CST) is slipped
over a length of wing-wire material
or drill rod of the same size that is
coated with release agent. (I’ve used
a double wrap of 1/4 mil Mylar.) The
sock is pulled tight and coated with
epoxy laminating resin. Excess epoxy is
blotted off.
After the epoxy hardens, the wire is
removed, leaving a rigid carbon-fiber
tube socket that’s a perfect fit for the
wing wire. For larger models, a second
sock can be added over the first for
extra strength. You can cut the socket
to length for each wing half or, better
yet, cut it to double length and build
it into both right- and left-wing inner
panels at the same time, ensuring
accurate alignment.
Don’t do as I did and glue the wing
socket permanently to the wing wire
I was using to align two main spar
halves while installing the sockets.
The carbon-fiber sock tubing I had
made was porous enough to let some
CA soak through to the wing wire.
(I intended to tack the sockets in
place with CA so the wing wire could
be removed and the socket-to-spar
joint filled in with epoxy and micro
balloons.)
Paul Crowley offers another option
to ensure a perfect fit: “I run a pipe
cleaner with epoxy on it to coat the
inside of the aluminum tube, then I
bore it out to size with a new, sharp
drill bit when it’s set,” he said. (I’ve
done it the other way around by
brushing slow epoxy glue onto a long
section of too-small carbon-fiber tube
and hanging the rod up to dry.)
The wing sockets must be tied into
the main spar structure. Ideally, the
wing socket is sandwiched between
upper and lower carbon-fiber caps in a
full-depth spar.
For the pylon or fuselage socket,
you can use a section of the carbonfiber
socket or make a custom-fit
aluminum tube. K&S, supplier of the
brass and aluminum tubing available
at most hobby shops, produces a line
of thick-wall aluminum tubing in a
variety of ODs with a wall thickness
of either 0.035 inch or 0.049 inch;
the aluminum used (6061 T-6) is
slightly harder than that used for the
thin-wall tubing.
The thick-walled tubing can be
bored out using the correct size drill
bit, preferably on a lathe. Few hobby
shops carry thick-wall tubing; an
online source is Hobbylinc. Its website
includes thick-wall aluminum tubing
in a few metric sizes, as well as brass
tubing in metric sizes.
The brass tubing has a 0.45mm wall
thickness, so it doesn’t give a close
fit on metric-size wire. For example,
the clearance between 3.0mm OD
brass tubing and 2mm diameter wire
is 0.10mm (0.004 inch)—too loose
to use as a shaft bearing or wingwire
socket.
StarLink FliteTech Models
Michael Pykelny is the new owner
of StarLink FliteTech. He took over
from previous owner Larry Bagalini,
who ran the mail-order operation for
a number of years after founder Al
Brush passed away. The new contact
information is at the end of the column.
StarLink offers a variety of models
and kits, ranging from Russian flier
Andrey Burdov’s F1B Wakefield and
F1G Coupe models to innovative
P-30 kits. StarLink carries an updated
version of Bob White’s Beau Coupe
design and several Nostalgia and Old-
Timer Rubber kits.
Items for the shop and flying field,
including a machined aluminum
winding stooge and clear plastic storage
tubes for tracking transmitters, are also
available. Components such as motor
tubes, front ends, propeller blades, and
even wings for F1B and F1G aircraft
can be purchased.
Parts are stocked to allow upgrading
of older Burdov Coupe front ends.
These include adjustable blade fittings
and a replacement shaft that allows
you to use a bobbin to connect
the rubber motor to the front end,
permitting winding without the
propeller attached.
Sources :
NFFS
www.freeflight.org
CST-The Composites Store
(800) 338-1278
www.cstsales.com
A2Z Corp
(877) 754-7465
www.A2ZCorp.us/store
Hobbylinc
(888) 327-9673
www.hobbylinc.com
StarLink-FliteTech Models
(858) 231-4994
www.starlink-flitetech.com

112 Model Aviation May 2012 www.ModelAviation.com
off, Gina placed
second behind
a flier with 30-
plus years of
experience—her
father, Andrew.
The Junior
Team Committee,
consisting of Jim
Parker, Charlie
Jones, Tom Vaccaro, and George Batiuk,
is raising funds to help defray some of
the team’s expenses. AMA covers travel,
lodging, and entry fees, but extra support
is needed.
In February, the Junior Committee
raffled off one of the late Bob White’s
Wakefields, model number 23, which
was the backup model when Bob won
the World Championship in 1987. Bob’s
winning model, number 22, is on display
in the National Model Aviation Museum
in Muncie, Indiana.
Also raffled off was a quilt depicting
all of the previous Junior World
Championships sites made by Charlie
Jones’ mother. Donations can be made
by check to AMA and should be
earmarked for the Junior Free Flight
Team. You can also send a check directly
ff DURATION
T he 2012 FAI Junior World Championships for Free Flight Model Aircraft
will be held July 27 through August 3 near Ljubljana, Slovenia. The United
States will be represented by Gina Barron, Logan Tetrick, and Michelle
Barron in F1A Towline Glider; Sevak Malkhasyan, Brian Pacelli, and Peyton
Tetrick in F1B Wakefield Rubber; and Taron Malkhasyan and Brian Pacelli in F1P
Power. As of early February, the third
slot in F1P had not been filled.
Once again, Brian Pacelli will do
double duty, flying Wakefield and
F1P Power. This year’s team includes
a set of brothers, Sevak and Taron
Malkhasyan; brother and sister, Logan
and Peyton Tetrick; and sisters, Gina
and Michelle Barron. George Batiuk
will be team manager.
Gina, who will turn 10 during the
Junior World Championships, will
be one of the youngest contestants
to represent the US in any World
Championships. Although her F1A
Towline gliders may span twice her
height, she handles them with skill.
At a contest last fall in Seguin, Texas,
Gina picked her own air for all seven
rounds and was one of two contestants
to max out; both fliers maxed the
first fly-off round. In the second fly-
FF Junior World Champs
by Louis Joyner
[email protected]
PLUS:
> America Cup
> National Cup
> Two-piece wings
> StarLink FliteTech
models
Brian Pacelli, who will fly F1B and F1P in this year’s
Junior FF World Championships, winds the rubber
outside of the model. This allows for a quicker
change in case of a blown motor.
Peyton Tetrick made the F1B team
flying a Vivchar model; her brother,
Logan, made the team in F1A
Towline Glider.
Taron Malkhasyan made the Junior team
flying F1P Power. He was also high-scoring
Junior in F1J and F1P in the America’s Cup.
114 Model Aviation May 2012 www.ModelAviation.com
ff duration
Below: Michelle Barron and her sister, Gina, comprise
two-thirds of the Junior F1A team attending the World
Championships in Slovenia.
Left: StarLink-FliteTech Models offers a variety
of models, kits, and accessories, including this
replacement shaft and three-part bobbin used
to update the front end of Burdov F1G Coupe
models.
Taron’s brother, Sevak Malkhasyan,
made the Junior team in F1B, earned
top points in the National Cup Junior
category, and was high Junior in F1B in
the America’s Cup.
to team manager George Batiuk, 576
Dana St., San Luis Obispo CA 93401.
America’s Cup
The annual multi-contest
competition for all of the FAI FF
events concluded this December. Here
are the results:
F1A Towline Glider: Brian Van Nest
(Gina Barron, high Junior)
F1B Wakefield Rubber: Blake Jensen
(Sevak Malkhasyan, high Junior)
F1C: Faust Parker
F1G Coupe Rubber: Blake Jensen
(Troy Davis, high Junior)
F1H Towline Glider: Mike McKeever
(Gina Barron, high Junior)
F1J Power: Faust Parker (Taron
Malkhasyan, high Junior and 4th place
overall)
F1P Power: Glen Schneider (Taron
Malkhasyan, high Junior and tied for
3rd place overall)
F1Q Electric: John Oldenkamp
F1E Slope Soaring: Peter Brocks
The America’s Cup, which was
created by the Southern California
Aero Team and is administered by Jim
Parker, offers a multi-contest format
that encourages modelers from the
United States, Canada, and Mexico,
to compete in FAI FF events. Points
are awarded at each contest, with a
first place receiving 25, second place
receiving 20, third place receiving 15,
fourth place receiving 10, and fifth
place receiving 5 points.
Additional points are awarded
depending on the number of
contestants flying in the event. Best
results from four contests are counted.
To encourage travel, only two contests
at any one site can be counted; the
other two results must be from two
other sites. In the case of a tie, results
from more contests are counted.
Detailed rules for the America’s Cup
can be found on the National Free
Flight Society (NFFS) website.
National Cup
The National Cup was created in
2003 to encourage participants to
travel and compete at FF contests
across the country. As is the America’s
Cup, the National Cup is a multicontest
competition. However, the
National Cup focuses on AMA FF
events.
Contestants in each of seven
categories accumulate points in the
individual events within that category
at contests across the country. To score
points, contestants must place in the
top five in an event. The highest six
scores in each event are counted.
To make it truly a nationwide cup,
no more than two scores are counted
from any single location. A seventh
score can be added by placing at one
of four exempt contests in each of the
four NFFS regions. The contests are the
Southwest Regionals in Eloy, Arizona;
the AMA Nats in Muncie, Indiana;
the Rocky Mountain Championships
in Denver, Colorado; and the King
Orange Internationals in Palm Bay,
Florida. A third score from one of the
exempt contests is to be counted.
In 2011, there were 81 contests with
615 contestants posting scores in 1,762
individual events. The categories and
the 2011 winners are:
AMA Power: Bob Hanford
Classic Power: Bob Hanford
Nostalgia Power (small): Bob Hanford
Nostalgia Power (large): Bob Hanford
AMA Rubber: Earl Griffith
Nostalgia Rubber: Don DeLoach
Glider: Tim Batiuk
Bob Hanford won all four of the
Power categories.
The National Cup includes a Junior
category, which combines scores from
selected Rubber, Power, and Glider
events. Sevak Malkhasyan topped this
category, with Tyler Moore in second,
only 14 points behind. Samuel Smetzer
was third, Taron Malkhasyan came in
fourth, and Elliot Plantner placed fifth.
Rules, detailed scores, and the 2012
National Cup contest schedule can be
found on the NFFS website.
Two-Piece Wings
Fifty years ago, one-piece wings were
the rule, even for large FF models.
In those days, before minivans and
SUVs, large wings were often strapped,
upside down, to the headliner of the
family sedan for transport to the flying
field. Today, many models use twopiece
wings that allow more compact
storage—often in a purpose-made
model box that safely stores several
complete models for a car trip or an
international flight.
Two-piece wings allow easy
adjustment of the relative incidence
between the two wing halves
as a trimming aid. This can be
accomplished by shimming underneath
the TE on a two-piece wing, rubber
banded to a traditional pylon or rail
system on the fuselage. The two wing
halves can also be connected by a
single wire running through the pylon
or fuselage; often one half is located by
a fixed rear pin and the other half with
an adjustable pin.
The adjustable pin can be linked to a
timer, either through a line or a servo,
to change the incidence of the wing
half at a predetermined time during
the flight. Known as a wing wiggler,
its use is nearly universal in the larger
FAI classes of F1A Towline Glider, F1B
Wakefield Rubber, and F1C Power,
usually coupled with auto rudder and
auto stabilizer.
For smaller models, such as an F1G
Coupe d’Hiver, a wing wiggler can even
be used as the only auto surface. On
my Coupes, I use a simple wing wiggler
made from wire and tubing to control
the left wing. At launch, the left panel
is set at several degrees negative relative
to the right wing half. This provides a
left rolling tendency during the initial
burst.
After 5 to 7 seconds, a timer releases
a line, allowing the left TE to move
down to the glide position. The result
is a straight, near-vertical initial climb,
transitioning into a right cruise and
right glide. No other auto surfaces
are used. (Photographs and a detailed
description of this wing wiggler can
be found in MA’s November 2010 “FF
Duration” column.)
A two-piece wing requires slightly
more effort during construction, but
the convenience of adjusting the wing
halves independently, as well as the
compactness, make it worth the effort.
Two-piece wings are often heavier
than a one-piece wing. The wing wire,
sockets in the two wing halves, and the
socket and additional reinforcing in the
pylon or fuselage, all add weight; this
is partially offset by eliminating the
center section reinforcements needed
with a one-piece wing.
The wing wire is often the main
offender concerning weight. In the past,
steel wire has been the most popular
choice. Typical diameters range from
3.0mm (slightly less than 1/8 inch) for
F1B, to 5.5mm to 6.0mm (less than 1/4
inch) for F1A and F1C. Steel wire can
also bend during a hard towline launch
or on DT.
Carbon fiber has been tried as a
lighter-weight alternative. The weight
saving can be significant. On his
F1B models, Paul Crowley has tried
substituting 1/8-inch diameter carbonfiber
rod for 1/8-inch steel wing wires.
“The weight saving was nice; 1 gram
for carbon versus 4 grams for steel,” he
said.
But there were problems. “I found
that the carbon-fiber rods would break
after repeated use, usually on launch,”
said Paul. “But the break was actually
promoted by hard DT landings. I
believe that the shear load at the pylon
was the cause; rounding the corners of
the holes didn’t help. The carbon-fiber
rod is a bundle of strands and you start
breaking them one at a time until the
strands that are left can’t take the stress
of a hard launch or DT.”
A solution is to protect the carbon
fiber with steel. One method is to
use thin-wall stainless steel tubing of
the desired diameter and fill it with
carbon-fiber tow wetted out with
epoxy. This can be done by inserting a
loop of Kevlar thread through a length
of steel tubing, then using the Kevlar
thread to pull a bundle of doubled
lengths of epoxy-soaked carbon-fiber
tow back through the tube.
For lighter models, such as F1G
Coupe and other Rubber models,
carbon-fiber rods or tubes still offer the
best weight-to-strength option for wing
wires. The popular Burdov Candy G
Coupe uses a purpose-made 4.5mmdiameter
carbon tube; carbon-tube
pultrusions, available from A2Z Corp
and CST, are offered in 3mm, 4mm,
and 5mm, which would be suitable for
many smaller, lightly-loaded models. (I
have had no problems using the 4.0mm
pultrusion for the wing wire on my
Coupes.) To avoid problems, frequently
inspect and replace carbon wing rods
or tubes.
Whatever you use for the wing wire,
it must fit properly into sockets in the
wings. Standard piano wire and the
next larger size aluminum tubing fits
too loosely. Aluminum tubing from
K&S has a wall thickness of 0.014 inch.
If you use 5/32-inch OD aluminum
tubing, the ID will be 0.12825; that’s
0.00325 inch bigger than 1/8-inch
piano wire. Not quite sloppy, but
loose enough to potentially cause trim
problems.
How do you get a perfect fit? One
solution is to make your own wing
sockets using a carbon-fiber sock. The
sock (available from CST) is slipped
over a length of wing-wire material
or drill rod of the same size that is
coated with release agent. (I’ve used
a double wrap of 1/4 mil Mylar.) The
sock is pulled tight and coated with
epoxy laminating resin. Excess epoxy is
blotted off.
After the epoxy hardens, the wire is
removed, leaving a rigid carbon-fiber
tube socket that’s a perfect fit for the
wing wire. For larger models, a second
sock can be added over the first for
extra strength. You can cut the socket
to length for each wing half or, better
yet, cut it to double length and build
it into both right- and left-wing inner
panels at the same time, ensuring
accurate alignment.
Don’t do as I did and glue the wing
socket permanently to the wing wire
I was using to align two main spar
halves while installing the sockets.
The carbon-fiber sock tubing I had
made was porous enough to let some
CA soak through to the wing wire.
(I intended to tack the sockets in
place with CA so the wing wire could
be removed and the socket-to-spar
joint filled in with epoxy and micro
balloons.)
Paul Crowley offers another option
to ensure a perfect fit: “I run a pipe
cleaner with epoxy on it to coat the
inside of the aluminum tube, then I
bore it out to size with a new, sharp
drill bit when it’s set,” he said. (I’ve
done it the other way around by
brushing slow epoxy glue onto a long
section of too-small carbon-fiber tube
and hanging the rod up to dry.)
The wing sockets must be tied into
the main spar structure. Ideally, the
wing socket is sandwiched between
upper and lower carbon-fiber caps in a
full-depth spar.
For the pylon or fuselage socket,
you can use a section of the carbonfiber
socket or make a custom-fit
aluminum tube. K&S, supplier of the
brass and aluminum tubing available
at most hobby shops, produces a line
of thick-wall aluminum tubing in a
variety of ODs with a wall thickness
of either 0.035 inch or 0.049 inch;
the aluminum used (6061 T-6) is
slightly harder than that used for the
thin-wall tubing.
The thick-walled tubing can be
bored out using the correct size drill
bit, preferably on a lathe. Few hobby
shops carry thick-wall tubing; an
online source is Hobbylinc. Its website
includes thick-wall aluminum tubing
in a few metric sizes, as well as brass
tubing in metric sizes.
The brass tubing has a 0.45mm wall
thickness, so it doesn’t give a close
fit on metric-size wire. For example,
the clearance between 3.0mm OD
brass tubing and 2mm diameter wire
is 0.10mm (0.004 inch)—too loose
to use as a shaft bearing or wingwire
socket.
StarLink FliteTech Models
Michael Pykelny is the new owner
of StarLink FliteTech. He took over
from previous owner Larry Bagalini,
who ran the mail-order operation for
a number of years after founder Al
Brush passed away. The new contact
information is at the end of the column.
StarLink offers a variety of models
and kits, ranging from Russian flier
Andrey Burdov’s F1B Wakefield and
F1G Coupe models to innovative
P-30 kits. StarLink carries an updated
version of Bob White’s Beau Coupe
design and several Nostalgia and Old-
Timer Rubber kits.
Items for the shop and flying field,
including a machined aluminum
winding stooge and clear plastic storage
tubes for tracking transmitters, are also
available. Components such as motor
tubes, front ends, propeller blades, and
even wings for F1B and F1G aircraft
can be purchased.
Parts are stocked to allow upgrading
of older Burdov Coupe front ends.
These include adjustable blade fittings
and a replacement shaft that allows
you to use a bobbin to connect
the rubber motor to the front end,
permitting winding without the
propeller attached.
Sources :
NFFS
www.freeflight.org
CST-The Composites Store
(800) 338-1278
www.cstsales.com
A2Z Corp
(877) 754-7465
www.A2ZCorp.us/store
Hobbylinc
(888) 327-9673
www.hobbylinc.com
StarLink-FliteTech Models
(858) 231-4994
www.starlink-flitetech.com