What kind of aileron?
Bob Aberle | baberle@? Frequently Asked Questions optonline.net
April 2011 81
Scale-type ailerons are often called “barn
door” types, as shown on an E-flite
Taylorcraft ARF. They are located on the
outer wing panels and are usually operated
by separate servos located out toward the
middle of each wing panel.
This is how a typical full-length strip aileron
looks. The chord of such an aileron is
usually a constant width from the fuselage
to the tips. One servo generally operates
both ailerons.
This Scale Travel Air Mystery Ship has scalelike barn door ailerons. The hinge work on
this model was done so well that it is hard to see the aileron.
PLEASE WRITE IN with your questions;
that is the only way we can keep this column
format going. When referring to already
published questions and answers (for followups),
always provide the number as a
reference.
Also note that references to addresses and
Web sites are placed in a group, separate from
the text, at the end of this column under
“Sources.” A “Tips” feature is provided in
addition to frequently asked questions; these
hints are numbered in the same sequence as
the questions and answers.
Q493: “I have noticed on some airplanes that
the ailerons run the full length of the wing,
while on others the aileron is only
approximately the outer half of the wing.
What is the difference? Is there a difference in
the flying characteristics? Is there a
relationship between the area of the wing and
the aileron?
“Also it seems that low-wing airplanes
always have the full-length ailerons, while
high-wing airplanes have both. Any
information you may have would be greatly
appreciated.”
A493: This is both an interesting and
important question. I have used full-length
strip ailerons on my sport models and the
“barn door” type on the outer wing panels of
my Scale aircraft. I asked my flying buddy,
Tom Hunt, for his thoughts on this subject.
After reading the question, he indicated
that his input would probably not answer all
of the questions on this subject; doing so
would require a full chapter in an
aerodynamics book. But for those who are
interested in a “starter course,” following is
his response.
“Years ago, when servos were big, heavy
and more expensive, strip ailerons were
actuated by a single servo. The aileron
extended nearly all the way to the sidewall of
the fuselage and was deflected via a short
‘torque rod.’
Also included in this column:
• Constructing cowls
• Simplicity flying wing
• Walt Mooney Peanut Scale plans
• Pioneer Flight Museum
04sig3x.QXD_00MSTRPG.QXD 2/22/11 11:33 AM Page 81
“There was no ‘good’ aerodynamic
reason for doing this; in fact many
designers did not give the aileron enough
‘chord’ to be aerodynamically efficient.
Many models suffered from poor roll
control with ‘strip’ ailerons, and increasing
the throw only compounded the problem by
introducing a problem called ‘adverse yaw’
(model banks left, but yaws to the right and
vice versa).
“Good strip aileron designs used
ailerons that had chords of at least 20% of
the entire wing chord. Since manufacturers
of ‘kits’ did not want the expense of
making tapered aileron stock for tapered
wing planforms, one always saw constant
chord ailerons on all wing designs (tapered
panels or constant chord panels).
“Ailerons that do not taper with the
wing are not necessarily bad, just a
compromise of manufacturability and
performance. Too much chord and too little
span can be as bad as too little chord on a
full span (strip) aileron.
“Big ‘barn door’ ailerons found on just
the outer half of the wing are susceptible to
flutter and without proper differential
deflection (more ‘up’ aileron than ‘down’),
this type of aileron can also create an
‘adverse yaw’ condition.
“The position of the wing on the
fuselage (and the type of aileron) has very
little to do with roll control. Size (percent
chord and span) is the main influence on
roll control.
“Today’s ‘3D’ aircraft need large
amounts of aileron area on the inboard
section of the wing to try to counteract the
torque of the engine/motor and propeller
system during the ‘hover phase’ of flight.
This excessive area becomes a burden in
normal horizontal flight at higher speeds,
and if not designed correctly
(mechanically) can cause some very serious
flutter failures and possibly crashes.
“Larger 3D models use multiple hightorque
servos on segmented inner and out
half aileron sections to reduce this risk.”
Thank you, Tom! If you want to add
your comments on this subject, please drop
me a note.
Q494: “My question concerns making
cowls from material other than balsa.
“I am completing a WACO ‘E’ which
requires a 61/4 inch diameter cowl. I’ve
tried working with fiberglass over a foam
mold and did not care for it. Could
you give me some other ideas for
building a custom cowl?”
A494: Not to sound commercial,
but there are companies that make a
variety of molded fiberglass cowls
for model aircraft. You can use any
Internet search engine to locate these
suppliers.
One that comes to mind is Fiberglass
Specialties; this company has been
around for a long time. I’ve listed the
contact information in “Sources.”
One of the techniques I’ve used
Left: The unique part of this Simplicity
f lat f lying wing i s that i t has no
vertical surfaces; it is strictly a flat
piece of Styrofoam. It takes no
time to construct, costs little,
and flies great!
throughout the years has been to make a
mold for a cowl from layers of 3/4-inch pink
insulation foam. You can get that material
from The Home Depot.
I use a band saw to rough out the foam
block and then sand it to shape. Then I
apply a layer of Saran Wrap over the mold
and add one or two layers of thin fiberglass
cloth over the Saran Wrap. Following that I
apply slow-curing epoxy cement or
polyester resin over the cloth.
The final step is to envelop the mold,
cloth, and cement with a large rubber
balloon. You literally stretch the balloon
over the entire mold. This brings the cloth
and cement in perfect and even contact
with the mold. After curing overnight, I
remove the resulting fiberglass shell from
the mold and trim it to fit my model.
This technique was well documented by
the old Pettit Paint Company’s Hobbypoxy
Division, which is no longer in existence. If
anyone has a copy of the “Balloon Method”
application sheet, please send it to me so I
can share it with readers.
Q495: “A friend of mine mentioned that he
saw a small flying wing design, that was
electric powered and had no vertical flying
surfaces at all. In other words, the airplane
was simply a flat triangular shaped wing.
“Based on this information can you
locate the design for me?”
A495: I got lucky with this question,
because a fellow Silent Electric Flyers of
Long Island club member has built one of
those models. The design appeared in a
British publication
that is part of
Traplet
Publications.
The model is
called the
“Simplicity,” and
John Rutter
designed it. It has a
wingspan of 24
inches, and the area
is 380 square
inches. The total
weight, with a small
82 MODEL AVIATION
Ready-made custom fiberglass cowls can be
purchased from companies such as
Fiberglass Specialties of Garfield AR, which
has stock cowls or will make them to your
molds.
Years ago, Bob made these cowl molds from
foam material. They were for special scale
model applications. The wood sticks allow
you to anchor your mold to a bench vise.
Above: Bob’s 20-year-old Aeronca L-3 Defender
employs a mold that was made with the old
Hobbypoxy “balloon method,” described in the
column. He is holding a spare cowl, to give you an
idea of how the raw cowl looks.
04sig3x.QXD_00MSTRPG.QXD 2/22/11 11:34 AM Page 82
April 2011 83
brushless outrunner motor and two-cell Li-
Poly battery, is 5.35 ounces.
The airplane appears to be constructed
from approximately 3/8-inch-thick white
foam. The interesting part of this design is
that it is flat, with no vertical surface such
as a fin or rudder. It is flown with elevon
and motor control.
I’ve seen this aircraft in flight, and it is
amazing. It is totally staple and requires no
gyro control; you simply fling it to launch
as you hit the throttle.
It can’t take more than a couple hours to
cut out, install the equipment, and head for
the flying field. Because it is made from
common foam sheet, it won’t cost much
either.
Traplet Publications does sell the plans;
I’ve included contact information in the
“Sources” section. The Web site can be
tricky at times, so please be patient. I’ve
also included a photo of the Simplicity that
I saw fly.
Q496: “For many years I read magazine
construction articles authored by noted
scale builder Walt Mooney. Did anyone
take the trouble of accumulating all of
Walt’s wonderful plans so that we might
revisit them today for micro/indoor RC
flying?”
A496: I found exactly what you are asking
for in Pat Tritle’s column that was
published in the December 2010 Flying
Models magazine. I’ve included the Web
site address under “Sources.” The page
contains tons of Walt’s plans, which can
easily be enlarged and printed at stores,
such as Staples, that have copy centers.
The page included much more,
including sections titled “Those early
years,” “Old time rubber endurance,” “Kit
and dime scale plans,” “Pnuts and
Pistachios,” “FF scale power,” and much
more. Give it a try; I think that you will be
pleased.
T497: AMA member Bill Gaston was kind
enough to mention a wonderful facility in
his area of Texas: the Pioneer Flight
Museum, which is part of the Vintage
Aviation Historical Foundation. The
museum is located at the Old Kingsbury
Aerodrome, which is 10 miles from Seguin
and roughly 40 miles east of San Antonio.
The owner built the Aerodrome to look
like a World War I airfield. Right now it
has six full-scale WW I aircraft that have
been restored to flying status. It’s similar to
the Old Rhinebeck Aerodrome in New
York, but it’s located in the middle of our
country.
I’ve included contact information for
the facility. The Web site features
scheduled events, the aircraft, photos, and
what’s planned for the future. Thanks for the
tip, Bill! MA
Sources:
Fiberglass Specialties Inc.
(479) 359-2429
www.fiberglassspecialtiesinc.com
Traplet Publications
+44(0)1684 588500
http://shop.traplet.com
Walt Mooney designs
http://bit.ly/fZ4ayH
Pioneer Flight Museum
(830) 639-4162
http://pioneerflightmuseum.org
AMA Academy of Model
Aeronautics
ARF Almost Ready to
Fly
BEC Battery Eliminator
Circuit
CA cyanoacrylate glue
CAD computer-aided
design
cc cubic centimeter
CD contest director
or compact disc
CG center of gravity
CL Control Line
cm centimeter
cu. in. cubic inch
dBA DeciBels Adjusted
(noise power
calculated in dB
[decibel])
DT dethermalizer
EAA Experimental
Aircraft Association
EPP (foam) expanded
polypropylene
ESC Electronic Speed
Control
EPS expanded
polystyrene foam
FAI Fédération
Aéronautique
Internationale
FAA Federal Aviation
Administration
FCC Federal
Communications
Commission
FF Free Flight
GHz gigahertz
ID inside diameter
Kv rpm/volt
kV kilovolt (1,000
volts)
LCD Liquid Crystal
Display
LE leading edge
LED light-emitting diode
Li-Poly Lithium Polymer
mA milliamperes
MA Model Aviation
mAh milliampere-hours
MHz megahertz
mm millimeter
Nats AMA Nationals
nitro nitromethane
Ni-Cd Nickel Cadmium
NiMH Nickel Metal
Hydride
OD outside diameter
RC Radio Control
rpm revolutions per
minute
RTF Ready to Fly
SASE self-addressed,
stamped envelope
SIG Special Interest
Group
TE trailing edge
Model Aviation’s
Frequently Used Abbreviations/Acronyms
04sig3x.QXD_00MSTRPG.QXD 2/22/11 11:35 AM Page 83
Edition: Model Aviation - 2011/04
Page Numbers: 81,82,83
Edition: Model Aviation - 2011/04
Page Numbers: 81,82,83
What kind of aileron?
Bob Aberle | baberle@? Frequently Asked Questions optonline.net
April 2011 81
Scale-type ailerons are often called “barn
door” types, as shown on an E-flite
Taylorcraft ARF. They are located on the
outer wing panels and are usually operated
by separate servos located out toward the
middle of each wing panel.
This is how a typical full-length strip aileron
looks. The chord of such an aileron is
usually a constant width from the fuselage
to the tips. One servo generally operates
both ailerons.
This Scale Travel Air Mystery Ship has scalelike barn door ailerons. The hinge work on
this model was done so well that it is hard to see the aileron.
PLEASE WRITE IN with your questions;
that is the only way we can keep this column
format going. When referring to already
published questions and answers (for followups),
always provide the number as a
reference.
Also note that references to addresses and
Web sites are placed in a group, separate from
the text, at the end of this column under
“Sources.” A “Tips” feature is provided in
addition to frequently asked questions; these
hints are numbered in the same sequence as
the questions and answers.
Q493: “I have noticed on some airplanes that
the ailerons run the full length of the wing,
while on others the aileron is only
approximately the outer half of the wing.
What is the difference? Is there a difference in
the flying characteristics? Is there a
relationship between the area of the wing and
the aileron?
“Also it seems that low-wing airplanes
always have the full-length ailerons, while
high-wing airplanes have both. Any
information you may have would be greatly
appreciated.”
A493: This is both an interesting and
important question. I have used full-length
strip ailerons on my sport models and the
“barn door” type on the outer wing panels of
my Scale aircraft. I asked my flying buddy,
Tom Hunt, for his thoughts on this subject.
After reading the question, he indicated
that his input would probably not answer all
of the questions on this subject; doing so
would require a full chapter in an
aerodynamics book. But for those who are
interested in a “starter course,” following is
his response.
“Years ago, when servos were big, heavy
and more expensive, strip ailerons were
actuated by a single servo. The aileron
extended nearly all the way to the sidewall of
the fuselage and was deflected via a short
‘torque rod.’
Also included in this column:
• Constructing cowls
• Simplicity flying wing
• Walt Mooney Peanut Scale plans
• Pioneer Flight Museum
04sig3x.QXD_00MSTRPG.QXD 2/22/11 11:33 AM Page 81
“There was no ‘good’ aerodynamic
reason for doing this; in fact many
designers did not give the aileron enough
‘chord’ to be aerodynamically efficient.
Many models suffered from poor roll
control with ‘strip’ ailerons, and increasing
the throw only compounded the problem by
introducing a problem called ‘adverse yaw’
(model banks left, but yaws to the right and
vice versa).
“Good strip aileron designs used
ailerons that had chords of at least 20% of
the entire wing chord. Since manufacturers
of ‘kits’ did not want the expense of
making tapered aileron stock for tapered
wing planforms, one always saw constant
chord ailerons on all wing designs (tapered
panels or constant chord panels).
“Ailerons that do not taper with the
wing are not necessarily bad, just a
compromise of manufacturability and
performance. Too much chord and too little
span can be as bad as too little chord on a
full span (strip) aileron.
“Big ‘barn door’ ailerons found on just
the outer half of the wing are susceptible to
flutter and without proper differential
deflection (more ‘up’ aileron than ‘down’),
this type of aileron can also create an
‘adverse yaw’ condition.
“The position of the wing on the
fuselage (and the type of aileron) has very
little to do with roll control. Size (percent
chord and span) is the main influence on
roll control.
“Today’s ‘3D’ aircraft need large
amounts of aileron area on the inboard
section of the wing to try to counteract the
torque of the engine/motor and propeller
system during the ‘hover phase’ of flight.
This excessive area becomes a burden in
normal horizontal flight at higher speeds,
and if not designed correctly
(mechanically) can cause some very serious
flutter failures and possibly crashes.
“Larger 3D models use multiple hightorque
servos on segmented inner and out
half aileron sections to reduce this risk.”
Thank you, Tom! If you want to add
your comments on this subject, please drop
me a note.
Q494: “My question concerns making
cowls from material other than balsa.
“I am completing a WACO ‘E’ which
requires a 61/4 inch diameter cowl. I’ve
tried working with fiberglass over a foam
mold and did not care for it. Could
you give me some other ideas for
building a custom cowl?”
A494: Not to sound commercial,
but there are companies that make a
variety of molded fiberglass cowls
for model aircraft. You can use any
Internet search engine to locate these
suppliers.
One that comes to mind is Fiberglass
Specialties; this company has been
around for a long time. I’ve listed the
contact information in “Sources.”
One of the techniques I’ve used
Left: The unique part of this Simplicity
f lat f lying wing i s that i t has no
vertical surfaces; it is strictly a flat
piece of Styrofoam. It takes no
time to construct, costs little,
and flies great!
throughout the years has been to make a
mold for a cowl from layers of 3/4-inch pink
insulation foam. You can get that material
from The Home Depot.
I use a band saw to rough out the foam
block and then sand it to shape. Then I
apply a layer of Saran Wrap over the mold
and add one or two layers of thin fiberglass
cloth over the Saran Wrap. Following that I
apply slow-curing epoxy cement or
polyester resin over the cloth.
The final step is to envelop the mold,
cloth, and cement with a large rubber
balloon. You literally stretch the balloon
over the entire mold. This brings the cloth
and cement in perfect and even contact
with the mold. After curing overnight, I
remove the resulting fiberglass shell from
the mold and trim it to fit my model.
This technique was well documented by
the old Pettit Paint Company’s Hobbypoxy
Division, which is no longer in existence. If
anyone has a copy of the “Balloon Method”
application sheet, please send it to me so I
can share it with readers.
Q495: “A friend of mine mentioned that he
saw a small flying wing design, that was
electric powered and had no vertical flying
surfaces at all. In other words, the airplane
was simply a flat triangular shaped wing.
“Based on this information can you
locate the design for me?”
A495: I got lucky with this question,
because a fellow Silent Electric Flyers of
Long Island club member has built one of
those models. The design appeared in a
British publication
that is part of
Traplet
Publications.
The model is
called the
“Simplicity,” and
John Rutter
designed it. It has a
wingspan of 24
inches, and the area
is 380 square
inches. The total
weight, with a small
82 MODEL AVIATION
Ready-made custom fiberglass cowls can be
purchased from companies such as
Fiberglass Specialties of Garfield AR, which
has stock cowls or will make them to your
molds.
Years ago, Bob made these cowl molds from
foam material. They were for special scale
model applications. The wood sticks allow
you to anchor your mold to a bench vise.
Above: Bob’s 20-year-old Aeronca L-3 Defender
employs a mold that was made with the old
Hobbypoxy “balloon method,” described in the
column. He is holding a spare cowl, to give you an
idea of how the raw cowl looks.
04sig3x.QXD_00MSTRPG.QXD 2/22/11 11:34 AM Page 82
April 2011 83
brushless outrunner motor and two-cell Li-
Poly battery, is 5.35 ounces.
The airplane appears to be constructed
from approximately 3/8-inch-thick white
foam. The interesting part of this design is
that it is flat, with no vertical surface such
as a fin or rudder. It is flown with elevon
and motor control.
I’ve seen this aircraft in flight, and it is
amazing. It is totally staple and requires no
gyro control; you simply fling it to launch
as you hit the throttle.
It can’t take more than a couple hours to
cut out, install the equipment, and head for
the flying field. Because it is made from
common foam sheet, it won’t cost much
either.
Traplet Publications does sell the plans;
I’ve included contact information in the
“Sources” section. The Web site can be
tricky at times, so please be patient. I’ve
also included a photo of the Simplicity that
I saw fly.
Q496: “For many years I read magazine
construction articles authored by noted
scale builder Walt Mooney. Did anyone
take the trouble of accumulating all of
Walt’s wonderful plans so that we might
revisit them today for micro/indoor RC
flying?”
A496: I found exactly what you are asking
for in Pat Tritle’s column that was
published in the December 2010 Flying
Models magazine. I’ve included the Web
site address under “Sources.” The page
contains tons of Walt’s plans, which can
easily be enlarged and printed at stores,
such as Staples, that have copy centers.
The page included much more,
including sections titled “Those early
years,” “Old time rubber endurance,” “Kit
and dime scale plans,” “Pnuts and
Pistachios,” “FF scale power,” and much
more. Give it a try; I think that you will be
pleased.
T497: AMA member Bill Gaston was kind
enough to mention a wonderful facility in
his area of Texas: the Pioneer Flight
Museum, which is part of the Vintage
Aviation Historical Foundation. The
museum is located at the Old Kingsbury
Aerodrome, which is 10 miles from Seguin
and roughly 40 miles east of San Antonio.
The owner built the Aerodrome to look
like a World War I airfield. Right now it
has six full-scale WW I aircraft that have
been restored to flying status. It’s similar to
the Old Rhinebeck Aerodrome in New
York, but it’s located in the middle of our
country.
I’ve included contact information for
the facility. The Web site features
scheduled events, the aircraft, photos, and
what’s planned for the future. Thanks for the
tip, Bill! MA
Sources:
Fiberglass Specialties Inc.
(479) 359-2429
www.fiberglassspecialtiesinc.com
Traplet Publications
+44(0)1684 588500
http://shop.traplet.com
Walt Mooney designs
http://bit.ly/fZ4ayH
Pioneer Flight Museum
(830) 639-4162
http://pioneerflightmuseum.org
AMA Academy of Model
Aeronautics
ARF Almost Ready to
Fly
BEC Battery Eliminator
Circuit
CA cyanoacrylate glue
CAD computer-aided
design
cc cubic centimeter
CD contest director
or compact disc
CG center of gravity
CL Control Line
cm centimeter
cu. in. cubic inch
dBA DeciBels Adjusted
(noise power
calculated in dB
[decibel])
DT dethermalizer
EAA Experimental
Aircraft Association
EPP (foam) expanded
polypropylene
ESC Electronic Speed
Control
EPS expanded
polystyrene foam
FAI Fédération
Aéronautique
Internationale
FAA Federal Aviation
Administration
FCC Federal
Communications
Commission
FF Free Flight
GHz gigahertz
ID inside diameter
Kv rpm/volt
kV kilovolt (1,000
volts)
LCD Liquid Crystal
Display
LE leading edge
LED light-emitting diode
Li-Poly Lithium Polymer
mA milliamperes
MA Model Aviation
mAh milliampere-hours
MHz megahertz
mm millimeter
Nats AMA Nationals
nitro nitromethane
Ni-Cd Nickel Cadmium
NiMH Nickel Metal
Hydride
OD outside diameter
RC Radio Control
rpm revolutions per
minute
RTF Ready to Fly
SASE self-addressed,
stamped envelope
SIG Special Interest
Group
TE trailing edge
Model Aviation’s
Frequently Used Abbreviations/Acronyms
04sig3x.QXD_00MSTRPG.QXD 2/22/11 11:35 AM Page 83
Edition: Model Aviation - 2011/04
Page Numbers: 81,82,83
What kind of aileron?
Bob Aberle | baberle@? Frequently Asked Questions optonline.net
April 2011 81
Scale-type ailerons are often called “barn
door” types, as shown on an E-flite
Taylorcraft ARF. They are located on the
outer wing panels and are usually operated
by separate servos located out toward the
middle of each wing panel.
This is how a typical full-length strip aileron
looks. The chord of such an aileron is
usually a constant width from the fuselage
to the tips. One servo generally operates
both ailerons.
This Scale Travel Air Mystery Ship has scalelike barn door ailerons. The hinge work on
this model was done so well that it is hard to see the aileron.
PLEASE WRITE IN with your questions;
that is the only way we can keep this column
format going. When referring to already
published questions and answers (for followups),
always provide the number as a
reference.
Also note that references to addresses and
Web sites are placed in a group, separate from
the text, at the end of this column under
“Sources.” A “Tips” feature is provided in
addition to frequently asked questions; these
hints are numbered in the same sequence as
the questions and answers.
Q493: “I have noticed on some airplanes that
the ailerons run the full length of the wing,
while on others the aileron is only
approximately the outer half of the wing.
What is the difference? Is there a difference in
the flying characteristics? Is there a
relationship between the area of the wing and
the aileron?
“Also it seems that low-wing airplanes
always have the full-length ailerons, while
high-wing airplanes have both. Any
information you may have would be greatly
appreciated.”
A493: This is both an interesting and
important question. I have used full-length
strip ailerons on my sport models and the
“barn door” type on the outer wing panels of
my Scale aircraft. I asked my flying buddy,
Tom Hunt, for his thoughts on this subject.
After reading the question, he indicated
that his input would probably not answer all
of the questions on this subject; doing so
would require a full chapter in an
aerodynamics book. But for those who are
interested in a “starter course,” following is
his response.
“Years ago, when servos were big, heavy
and more expensive, strip ailerons were
actuated by a single servo. The aileron
extended nearly all the way to the sidewall of
the fuselage and was deflected via a short
‘torque rod.’
Also included in this column:
• Constructing cowls
• Simplicity flying wing
• Walt Mooney Peanut Scale plans
• Pioneer Flight Museum
04sig3x.QXD_00MSTRPG.QXD 2/22/11 11:33 AM Page 81
“There was no ‘good’ aerodynamic
reason for doing this; in fact many
designers did not give the aileron enough
‘chord’ to be aerodynamically efficient.
Many models suffered from poor roll
control with ‘strip’ ailerons, and increasing
the throw only compounded the problem by
introducing a problem called ‘adverse yaw’
(model banks left, but yaws to the right and
vice versa).
“Good strip aileron designs used
ailerons that had chords of at least 20% of
the entire wing chord. Since manufacturers
of ‘kits’ did not want the expense of
making tapered aileron stock for tapered
wing planforms, one always saw constant
chord ailerons on all wing designs (tapered
panels or constant chord panels).
“Ailerons that do not taper with the
wing are not necessarily bad, just a
compromise of manufacturability and
performance. Too much chord and too little
span can be as bad as too little chord on a
full span (strip) aileron.
“Big ‘barn door’ ailerons found on just
the outer half of the wing are susceptible to
flutter and without proper differential
deflection (more ‘up’ aileron than ‘down’),
this type of aileron can also create an
‘adverse yaw’ condition.
“The position of the wing on the
fuselage (and the type of aileron) has very
little to do with roll control. Size (percent
chord and span) is the main influence on
roll control.
“Today’s ‘3D’ aircraft need large
amounts of aileron area on the inboard
section of the wing to try to counteract the
torque of the engine/motor and propeller
system during the ‘hover phase’ of flight.
This excessive area becomes a burden in
normal horizontal flight at higher speeds,
and if not designed correctly
(mechanically) can cause some very serious
flutter failures and possibly crashes.
“Larger 3D models use multiple hightorque
servos on segmented inner and out
half aileron sections to reduce this risk.”
Thank you, Tom! If you want to add
your comments on this subject, please drop
me a note.
Q494: “My question concerns making
cowls from material other than balsa.
“I am completing a WACO ‘E’ which
requires a 61/4 inch diameter cowl. I’ve
tried working with fiberglass over a foam
mold and did not care for it. Could
you give me some other ideas for
building a custom cowl?”
A494: Not to sound commercial,
but there are companies that make a
variety of molded fiberglass cowls
for model aircraft. You can use any
Internet search engine to locate these
suppliers.
One that comes to mind is Fiberglass
Specialties; this company has been
around for a long time. I’ve listed the
contact information in “Sources.”
One of the techniques I’ve used
Left: The unique part of this Simplicity
f lat f lying wing i s that i t has no
vertical surfaces; it is strictly a flat
piece of Styrofoam. It takes no
time to construct, costs little,
and flies great!
throughout the years has been to make a
mold for a cowl from layers of 3/4-inch pink
insulation foam. You can get that material
from The Home Depot.
I use a band saw to rough out the foam
block and then sand it to shape. Then I
apply a layer of Saran Wrap over the mold
and add one or two layers of thin fiberglass
cloth over the Saran Wrap. Following that I
apply slow-curing epoxy cement or
polyester resin over the cloth.
The final step is to envelop the mold,
cloth, and cement with a large rubber
balloon. You literally stretch the balloon
over the entire mold. This brings the cloth
and cement in perfect and even contact
with the mold. After curing overnight, I
remove the resulting fiberglass shell from
the mold and trim it to fit my model.
This technique was well documented by
the old Pettit Paint Company’s Hobbypoxy
Division, which is no longer in existence. If
anyone has a copy of the “Balloon Method”
application sheet, please send it to me so I
can share it with readers.
Q495: “A friend of mine mentioned that he
saw a small flying wing design, that was
electric powered and had no vertical flying
surfaces at all. In other words, the airplane
was simply a flat triangular shaped wing.
“Based on this information can you
locate the design for me?”
A495: I got lucky with this question,
because a fellow Silent Electric Flyers of
Long Island club member has built one of
those models. The design appeared in a
British publication
that is part of
Traplet
Publications.
The model is
called the
“Simplicity,” and
John Rutter
designed it. It has a
wingspan of 24
inches, and the area
is 380 square
inches. The total
weight, with a small
82 MODEL AVIATION
Ready-made custom fiberglass cowls can be
purchased from companies such as
Fiberglass Specialties of Garfield AR, which
has stock cowls or will make them to your
molds.
Years ago, Bob made these cowl molds from
foam material. They were for special scale
model applications. The wood sticks allow
you to anchor your mold to a bench vise.
Above: Bob’s 20-year-old Aeronca L-3 Defender
employs a mold that was made with the old
Hobbypoxy “balloon method,” described in the
column. He is holding a spare cowl, to give you an
idea of how the raw cowl looks.
04sig3x.QXD_00MSTRPG.QXD 2/22/11 11:34 AM Page 82
April 2011 83
brushless outrunner motor and two-cell Li-
Poly battery, is 5.35 ounces.
The airplane appears to be constructed
from approximately 3/8-inch-thick white
foam. The interesting part of this design is
that it is flat, with no vertical surface such
as a fin or rudder. It is flown with elevon
and motor control.
I’ve seen this aircraft in flight, and it is
amazing. It is totally staple and requires no
gyro control; you simply fling it to launch
as you hit the throttle.
It can’t take more than a couple hours to
cut out, install the equipment, and head for
the flying field. Because it is made from
common foam sheet, it won’t cost much
either.
Traplet Publications does sell the plans;
I’ve included contact information in the
“Sources” section. The Web site can be
tricky at times, so please be patient. I’ve
also included a photo of the Simplicity that
I saw fly.
Q496: “For many years I read magazine
construction articles authored by noted
scale builder Walt Mooney. Did anyone
take the trouble of accumulating all of
Walt’s wonderful plans so that we might
revisit them today for micro/indoor RC
flying?”
A496: I found exactly what you are asking
for in Pat Tritle’s column that was
published in the December 2010 Flying
Models magazine. I’ve included the Web
site address under “Sources.” The page
contains tons of Walt’s plans, which can
easily be enlarged and printed at stores,
such as Staples, that have copy centers.
The page included much more,
including sections titled “Those early
years,” “Old time rubber endurance,” “Kit
and dime scale plans,” “Pnuts and
Pistachios,” “FF scale power,” and much
more. Give it a try; I think that you will be
pleased.
T497: AMA member Bill Gaston was kind
enough to mention a wonderful facility in
his area of Texas: the Pioneer Flight
Museum, which is part of the Vintage
Aviation Historical Foundation. The
museum is located at the Old Kingsbury
Aerodrome, which is 10 miles from Seguin
and roughly 40 miles east of San Antonio.
The owner built the Aerodrome to look
like a World War I airfield. Right now it
has six full-scale WW I aircraft that have
been restored to flying status. It’s similar to
the Old Rhinebeck Aerodrome in New
York, but it’s located in the middle of our
country.
I’ve included contact information for
the facility. The Web site features
scheduled events, the aircraft, photos, and
what’s planned for the future. Thanks for the
tip, Bill! MA
Sources:
Fiberglass Specialties Inc.
(479) 359-2429
www.fiberglassspecialtiesinc.com
Traplet Publications
+44(0)1684 588500
http://shop.traplet.com
Walt Mooney designs
http://bit.ly/fZ4ayH
Pioneer Flight Museum
(830) 639-4162
http://pioneerflightmuseum.org
AMA Academy of Model
Aeronautics
ARF Almost Ready to
Fly
BEC Battery Eliminator
Circuit
CA cyanoacrylate glue
CAD computer-aided
design
cc cubic centimeter
CD contest director
or compact disc
CG center of gravity
CL Control Line
cm centimeter
cu. in. cubic inch
dBA DeciBels Adjusted
(noise power
calculated in dB
[decibel])
DT dethermalizer
EAA Experimental
Aircraft Association
EPP (foam) expanded
polypropylene
ESC Electronic Speed
Control
EPS expanded
polystyrene foam
FAI Fédération
Aéronautique
Internationale
FAA Federal Aviation
Administration
FCC Federal
Communications
Commission
FF Free Flight
GHz gigahertz
ID inside diameter
Kv rpm/volt
kV kilovolt (1,000
volts)
LCD Liquid Crystal
Display
LE leading edge
LED light-emitting diode
Li-Poly Lithium Polymer
mA milliamperes
MA Model Aviation
mAh milliampere-hours
MHz megahertz
mm millimeter
Nats AMA Nationals
nitro nitromethane
Ni-Cd Nickel Cadmium
NiMH Nickel Metal
Hydride
OD outside diameter
RC Radio Control
rpm revolutions per
minute
RTF Ready to Fly
SASE self-addressed,
stamped envelope
SIG Special Interest
Group
TE trailing edge
Model Aviation’s
Frequently Used Abbreviations/Acronyms
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