AGS Retro - 2008/02

16 MODEL AVIATION
BY BOB NOLL AND KEN MARONI
Photos by the author
Bob Noll (L) and Ken Maroni in front of the Aeroguidance Society’s
field sign. The Retro is a design of the airplane in the logo.
AGS
THIS IS THE story of a little sky-blue model that became famous
even before it learned how to fly. I am referring to the airplane on
the club logo of the Aeroguidance Society, Inc.—one of the oldest
RC clubs in the US.
In 2005 the Aeroguidance Society celebrated its 50th year of
service to aeromodeling and to the AMA. The club received the
Academy’s President’s Award for this accomplishment and for
hosting 50 consecutive RC Aerobatics (Pattern) contests. In 2004
the Aeroguidance Society started preparing to commemorate this
milestone event.
One of the activities suggested at the first planning meeting was
to design, build, and fly a replica of the little blue airplane. This
sounded like a great idea, and we were fortunate to have an
experienced designer—Ken Maroni—in the club and as a member
of the committee. He had designed several successful models, and I
volunteered to build this one.
The airplane had to resemble the one on the club logo, with its
high thrustline, low and rounded wing, stabilizer, and fin tips. It had
to be a tail-dragger, and we wanted a model that could be flown
adequately with a .40 cu. in. engine.
It was not long before Ken presented his first draft of the design
at a committee meeting, and we knew we were on the way to an
exciting chapter in the long history of the Aeroguidance Society.
After several design review sessions between Ken and me to adjust
the fuselage profile and make some minor construction changes, it
was time to start building.
We had decided to design and build both a Class II (rudder,
elevator, and throttle) and a Class III (aileron, elevator, rudder, and
throttle) model. (The Class I and II designations come from early
Retro
An artist rendering inspired this
great 40-size sport model
02sig1.QXD 12/20/07 9:23 AM Page 16February 2008 17
Just one 1/4-20 bolt is needed to secure the wing. The aluminum
gear is good for rough fields.
A good technique for making sure the formers are properly
shaped before sheeting is to mark with Magic Marker and use a
sanding bar to rub down high spots.
The AGS Retro takes off for a demonstration flight at the 50th Annual Aeroguidance
Society Precision Aerobatics Contest.
The battery is near center with the receiver in the front of
the equipment compartment. The model balanced perfectly
with this arrangement.
A Sig Four-Star 1.20 (kit RC65) canopy was trimmed to a pleasing fit. It
houses a doll bust from the local craft store.
AMA Pattern competition classes, when the
class that was flown depended on the
controls that were used. Class I was flown
with rudder and throttle control only.) Why
would we want to do this?
When the Aeroguidance Society was
formed in 1954, few RC airplanes had
ailerons. The one on the club logo didn’t; it
had a large dihedral angle, which was
necessary if ailerons were not going to be
used.
To be authentic we decided that the little
blue airplane should certainly be built
without ailerons, but we recognized that
most of today’s modelers would prefer to
have ailerons on their model. To make it
simpler for me, as the builder, I would
construct one fuselage with two wings. It
sounded like a good plan!
Now for the good news/bad news part of
this story; first is the bad news. I built the
first airplane for Class II—the one without
ailerons. Ken had never designed a Class II
02sig1.QXD 12/20/07 9:32 AM Page 1718 MODEL AVIATION
The fuselage is built with 1/4-inch square trusses to keep its weight
low and a sheeted turtledeck to make the structure rigid.
The Thunder Tiger .46 proved to be more than ample power for
this model. The engine is tilted so the high thrustline can be
maintained.
The top of the fuselage is sheeted with 3/32 balsa. Make sure to
sand the formers so that the sheeting fits flush.
Left: The Retro is made using conventional
wood construction throughout. This sport
model has good precision potential.
Above: The tail-feather parts are built up
with 1/4 square balsa sticks that are
sheeted with a 1/16 balsa skin.
The shape of the wingtips reflects the design of the little blue
airplane on the club logo. A shaped laminate technique is used.
02sig1.QXD 12/20/07 11:15 AM Page 18February 2008 19
The Retro has a distinguished appearance in the air—just like the
little blue airplane on the Aeroguidance Society logo.
A single aileron servo connected to torque rods provides linkage
to the ailerons. There’s plenty of control authority.
Single pushrods are used for the rudder and the elevator. Fuel tubing keeps the clevises
closed, and a longer piece acts as a shock-absorbing steering linkage for the tail wheel.
aircraft since all his models had ailerons,
which is what most designers use today.
However, we knew that the little blue
airplane on the logo didn’t have ailerons.
And the way you overcome the lack of
ailerons is to increase the wing dihedral.
That seemed easy enough.
We learned by experience that there was
not enough dihedral in the wing, which led
to a hairy first flight. To this day I am not
sure how I managed to keep the airplane
from crashing; it didn’t fly with its wings
level from after the first turn until I managed
to straighten it out for a damage-free
landing. My many years of flying must have
caused me to reach instinctively without
having time to think about the situation I
was in.
Several club members witnessed that first
flight, and we spent roughly 10 minutes
reflecting on what had happened. The
dihedral was not enough to allow the rudder
to do its job of turning the model.
In fact, as I applied left rudder for that
first turn the darned airplane decided it
wanted to fly on its left side. Go figure that
one out!
Now for the good news. I immediately
went home and cut ailerons into the wing,
which took only a day, and went back to the
field for the test flight of the then-Class III
model. The next flight was great, with only a
few minor trim changes.
After that I was confident with the design
and performed most of the maneuvers in my
repertoire. Loops and Rolls were good, but I
was more impressed with the little blue
airplane’s ability to do clean Stall Turns,
Point Rolls, and Snap Rolls. I was happy,
especially after that first flight a few days
earlier.
The model made its public debut at the
Type: RC sport monoplane
Builder skill level: Basic
Pilot skill level: Intermediate
Wingspan: 62.25 inches
Wing area: 671.3 square inches
Length: 56 inches
Weight: 4-6 pounds
Wing loading (average): 17.6
ounces/square foot
Engine: .40-.46 two-stroke
Radio: Three to four channels with
three or four standard servos
Construction: Balsa/plywood
Covering/finish: Builder’s choice;
MonoKote was used
AGS Retro
50th Annual Aeroguidance Society Precision
Aerobatics Contest, which took place just a
few weeks after those test flights. The AGS
Retro, as it is now known, has become a
part of the club’s rich history. I never did
build another wing without ailerons. I am an
easy learner.
This model is something different for the
“they all look alike” crowd. Give it a try.
Following is Ken’s account of some of the
AGS Retro’s design parameters.
The CG location is between the 30% and
33% point of the wing chord. I started at
25%-30% for initial flight. The tail moment
is 31.84 inches based on one-quarter chord
of each flight surface (wing and stabilizer).
The wing area is 671 square inches and the
stabilizer is 157.8 square inches.
The wing airfoil is basically an NACA
2415 with a fellow modeler’s alterations.
02sig1.QXD 12/20/07 9:42 AM Page 1920 MODEL AVIATION
The modification is flat on the bottom of the
airfoil from the 20% point to make it
possible to build on a flat surface without a
wing fixture. This airfoil has been used for
many models.
The fuselage was designed with a
laminated main fuselage body and truss
assembly for the empennage. The fuselage
lamination consists of light plywood as a
skeleton and a medium-grade balsa as the
laminate. This gives the fuselage body
strength and light weight. The truss
empennage section is integrated into the
main body of the fuselage to aid in strength
and distribution of moment forces.
The fuselage formers, landing-gear
mount plate, fuel-tank floor, and firewall are
notched to interlock with the fuselage sides
and associated formers. The engine firewall
has 2° of offset and is integrated as part of
the fuselage side construction.
The wing is of standard D-tube
construction with shear webs, planking on
the TE, and rib capstrips. The wing halves
are assembled using a dihedral brace that
ties the upper and lower spars together. The
brace also gives the wing its required
dihedral angle. The LE is formed by two
pieces of stick balsa glued together and
shaped to the LE radius. This technique
makes for an extremely strong assembly.
The tail feathers are of stick construction
and are sheeted with balsa.
The engine is mounted at a 45° angle to
create a clean, sleek appearance, with the
muffler tucked in close to the fuselage side.
Many of the accessories, such as the
canopy, landing gear, and tail wheel, are
common parts you can purchase through
Internet distributors or hobby shops. The
servos and flight-surface control
components, including the linkages, are
sized to suit a standard 40-size model.
The AGS Retro’s construction is simple
and straightforward. No special building
techniques are required, which makes this
project enjoyable for all levels of
pilots/builders. MA
Bob Noll
[email protected]
Ken Maroni
[email protected]
WHY WORRY?
THE HIGH CURRENT ALTERNATIVE TO LI-POLYMER
NOW AVAILABLE FOR RX, POWERBOX & ECU APPLICATIONS
• Take the worry out of charging with li-manganese chemistry
• No risk of fire if punctured or overcharged
• 20c discharge - 40c bursts
• High charge rate – up to 10c through the power lead
• No need to remove for charging
• No need to balance pack – built with Stay Balance Circuitry
• Great low temperature tolerance
• Longer life cycles than Li-Polymers
• Wiring options; 16 gauge High Current, 14 gauge Electric
Motor / Flight applications
• See our new expanded line of li-manganese batteries online
LITHIUM POWER SOLUTIONS FOR EVERYTHING YOU FLY
Order toll free 877-744-3685
Shop online www.duraliteflightsystems.com
LI-MANGANESE BATTERIES
ARE NON-FLAMMABLE!
TIRED OF PAYING
$1.29 FOR 6 SCREWS?
Our 4-40x1/2 socket
caps sell for $4.35/100
for alloy steel, or
$6.65/100 stainless, or $7.50/50 aluminum.
For fair prices on sensible quantities of the fasteners
you need for model building, call, write or
fax for our free catalog!
Micro Fasteners 800-892-6917
24 Cokesbury Rd., Suite 2 908-236-8120
Lebanon, NJ 08833 fax 908-236-8721
e-mail: [email protected] Internet: http://microfasteners.com
02sig1.QXD 12/20/07 11:22 AM Page 20

16 MODEL AVIATION
BY BOB NOLL AND KEN MARONI
Photos by the author
Bob Noll (L) and Ken Maroni in front of the Aeroguidance Society’s
field sign. The Retro is a design of the airplane in the logo.
AGS
THIS IS THE story of a little sky-blue model that became famous
even before it learned how to fly. I am referring to the airplane on
the club logo of the Aeroguidance Society, Inc.—one of the oldest
RC clubs in the US.
In 2005 the Aeroguidance Society celebrated its 50th year of
service to aeromodeling and to the AMA. The club received the
Academy’s President’s Award for this accomplishment and for
hosting 50 consecutive RC Aerobatics (Pattern) contests. In 2004
the Aeroguidance Society started preparing to commemorate this
milestone event.
One of the activities suggested at the first planning meeting was
to design, build, and fly a replica of the little blue airplane. This
sounded like a great idea, and we were fortunate to have an
experienced designer—Ken Maroni—in the club and as a member
of the committee. He had designed several successful models, and I
volunteered to build this one.
The airplane had to resemble the one on the club logo, with its
high thrustline, low and rounded wing, stabilizer, and fin tips. It had
to be a tail-dragger, and we wanted a model that could be flown
adequately with a .40 cu. in. engine.
It was not long before Ken presented his first draft of the design
at a committee meeting, and we knew we were on the way to an
exciting chapter in the long history of the Aeroguidance Society.
After several design review sessions between Ken and me to adjust
the fuselage profile and make some minor construction changes, it
was time to start building.
We had decided to design and build both a Class II (rudder,
elevator, and throttle) and a Class III (aileron, elevator, rudder, and
throttle) model. (The Class I and II designations come from early
Retro
An artist rendering inspired this
great 40-size sport model
02sig1.QXD 12/20/07 9:23 AM Page 16February 2008 17
Just one 1/4-20 bolt is needed to secure the wing. The aluminum
gear is good for rough fields.
A good technique for making sure the formers are properly
shaped before sheeting is to mark with Magic Marker and use a
sanding bar to rub down high spots.
The AGS Retro takes off for a demonstration flight at the 50th Annual Aeroguidance
Society Precision Aerobatics Contest.
The battery is near center with the receiver in the front of
the equipment compartment. The model balanced perfectly
with this arrangement.
A Sig Four-Star 1.20 (kit RC65) canopy was trimmed to a pleasing fit. It
houses a doll bust from the local craft store.
AMA Pattern competition classes, when the
class that was flown depended on the
controls that were used. Class I was flown
with rudder and throttle control only.) Why
would we want to do this?
When the Aeroguidance Society was
formed in 1954, few RC airplanes had
ailerons. The one on the club logo didn’t; it
had a large dihedral angle, which was
necessary if ailerons were not going to be
used.
To be authentic we decided that the little
blue airplane should certainly be built
without ailerons, but we recognized that
most of today’s modelers would prefer to
have ailerons on their model. To make it
simpler for me, as the builder, I would
construct one fuselage with two wings. It
sounded like a good plan!
Now for the good news/bad news part of
this story; first is the bad news. I built the
first airplane for Class II—the one without
ailerons. Ken had never designed a Class II
02sig1.QXD 12/20/07 9:32 AM Page 1718 MODEL AVIATION
The fuselage is built with 1/4-inch square trusses to keep its weight
low and a sheeted turtledeck to make the structure rigid.
The Thunder Tiger .46 proved to be more than ample power for
this model. The engine is tilted so the high thrustline can be
maintained.
The top of the fuselage is sheeted with 3/32 balsa. Make sure to
sand the formers so that the sheeting fits flush.
Left: The Retro is made using conventional
wood construction throughout. This sport
model has good precision potential.
Above: The tail-feather parts are built up
with 1/4 square balsa sticks that are
sheeted with a 1/16 balsa skin.
The shape of the wingtips reflects the design of the little blue
airplane on the club logo. A shaped laminate technique is used.
02sig1.QXD 12/20/07 11:15 AM Page 18February 2008 19
The Retro has a distinguished appearance in the air—just like the
little blue airplane on the Aeroguidance Society logo.
A single aileron servo connected to torque rods provides linkage
to the ailerons. There’s plenty of control authority.
Single pushrods are used for the rudder and the elevator. Fuel tubing keeps the clevises
closed, and a longer piece acts as a shock-absorbing steering linkage for the tail wheel.
aircraft since all his models had ailerons,
which is what most designers use today.
However, we knew that the little blue
airplane on the logo didn’t have ailerons.
And the way you overcome the lack of
ailerons is to increase the wing dihedral.
That seemed easy enough.
We learned by experience that there was
not enough dihedral in the wing, which led
to a hairy first flight. To this day I am not
sure how I managed to keep the airplane
from crashing; it didn’t fly with its wings
level from after the first turn until I managed
to straighten it out for a damage-free
landing. My many years of flying must have
caused me to reach instinctively without
having time to think about the situation I
was in.
Several club members witnessed that first
flight, and we spent roughly 10 minutes
reflecting on what had happened. The
dihedral was not enough to allow the rudder
to do its job of turning the model.
In fact, as I applied left rudder for that
first turn the darned airplane decided it
wanted to fly on its left side. Go figure that
one out!
Now for the good news. I immediately
went home and cut ailerons into the wing,
which took only a day, and went back to the
field for the test flight of the then-Class III
model. The next flight was great, with only a
few minor trim changes.
After that I was confident with the design
and performed most of the maneuvers in my
repertoire. Loops and Rolls were good, but I
was more impressed with the little blue
airplane’s ability to do clean Stall Turns,
Point Rolls, and Snap Rolls. I was happy,
especially after that first flight a few days
earlier.
The model made its public debut at the
Type: RC sport monoplane
Builder skill level: Basic
Pilot skill level: Intermediate
Wingspan: 62.25 inches
Wing area: 671.3 square inches
Length: 56 inches
Weight: 4-6 pounds
Wing loading (average): 17.6
ounces/square foot
Engine: .40-.46 two-stroke
Radio: Three to four channels with
three or four standard servos
Construction: Balsa/plywood
Covering/finish: Builder’s choice;
MonoKote was used
AGS Retro
50th Annual Aeroguidance Society Precision
Aerobatics Contest, which took place just a
few weeks after those test flights. The AGS
Retro, as it is now known, has become a
part of the club’s rich history. I never did
build another wing without ailerons. I am an
easy learner.
This model is something different for the
“they all look alike” crowd. Give it a try.
Following is Ken’s account of some of the
AGS Retro’s design parameters.
The CG location is between the 30% and
33% point of the wing chord. I started at
25%-30% for initial flight. The tail moment
is 31.84 inches based on one-quarter chord
of each flight surface (wing and stabilizer).
The wing area is 671 square inches and the
stabilizer is 157.8 square inches.
The wing airfoil is basically an NACA
2415 with a fellow modeler’s alterations.
02sig1.QXD 12/20/07 9:42 AM Page 1920 MODEL AVIATION
The modification is flat on the bottom of the
airfoil from the 20% point to make it
possible to build on a flat surface without a
wing fixture. This airfoil has been used for
many models.
The fuselage was designed with a
laminated main fuselage body and truss
assembly for the empennage. The fuselage
lamination consists of light plywood as a
skeleton and a medium-grade balsa as the
laminate. This gives the fuselage body
strength and light weight. The truss
empennage section is integrated into the
main body of the fuselage to aid in strength
and distribution of moment forces.
The fuselage formers, landing-gear
mount plate, fuel-tank floor, and firewall are
notched to interlock with the fuselage sides
and associated formers. The engine firewall
has 2° of offset and is integrated as part of
the fuselage side construction.
The wing is of standard D-tube
construction with shear webs, planking on
the TE, and rib capstrips. The wing halves
are assembled using a dihedral brace that
ties the upper and lower spars together. The
brace also gives the wing its required
dihedral angle. The LE is formed by two
pieces of stick balsa glued together and
shaped to the LE radius. This technique
makes for an extremely strong assembly.
The tail feathers are of stick construction
and are sheeted with balsa.
The engine is mounted at a 45° angle to
create a clean, sleek appearance, with the
muffler tucked in close to the fuselage side.
Many of the accessories, such as the
canopy, landing gear, and tail wheel, are
common parts you can purchase through
Internet distributors or hobby shops. The
servos and flight-surface control
components, including the linkages, are
sized to suit a standard 40-size model.
The AGS Retro’s construction is simple
and straightforward. No special building
techniques are required, which makes this
project enjoyable for all levels of
pilots/builders. MA
Bob Noll
[email protected]
Ken Maroni
[email protected]
WHY WORRY?
THE HIGH CURRENT ALTERNATIVE TO LI-POLYMER
NOW AVAILABLE FOR RX, POWERBOX & ECU APPLICATIONS
• Take the worry out of charging with li-manganese chemistry
• No risk of fire if punctured or overcharged
• 20c discharge - 40c bursts
• High charge rate – up to 10c through the power lead
• No need to remove for charging
• No need to balance pack – built with Stay Balance Circuitry
• Great low temperature tolerance
• Longer life cycles than Li-Polymers
• Wiring options; 16 gauge High Current, 14 gauge Electric
Motor / Flight applications
• See our new expanded line of li-manganese batteries online
LITHIUM POWER SOLUTIONS FOR EVERYTHING YOU FLY
Order toll free 877-744-3685
Shop online www.duraliteflightsystems.com
LI-MANGANESE BATTERIES
ARE NON-FLAMMABLE!
TIRED OF PAYING
$1.29 FOR 6 SCREWS?
Our 4-40x1/2 socket
caps sell for $4.35/100
for alloy steel, or
$6.65/100 stainless, or $7.50/50 aluminum.
For fair prices on sensible quantities of the fasteners
you need for model building, call, write or
fax for our free catalog!
Micro Fasteners 800-892-6917
24 Cokesbury Rd., Suite 2 908-236-8120
Lebanon, NJ 08833 fax 908-236-8721
e-mail: [email protected] Internet: http://microfasteners.com
02sig1.QXD 12/20/07 11:22 AM Page 20

16 MODEL AVIATION
BY BOB NOLL AND KEN MARONI
Photos by the author
Bob Noll (L) and Ken Maroni in front of the Aeroguidance Society’s
field sign. The Retro is a design of the airplane in the logo.
AGS
THIS IS THE story of a little sky-blue model that became famous
even before it learned how to fly. I am referring to the airplane on
the club logo of the Aeroguidance Society, Inc.—one of the oldest
RC clubs in the US.
In 2005 the Aeroguidance Society celebrated its 50th year of
service to aeromodeling and to the AMA. The club received the
Academy’s President’s Award for this accomplishment and for
hosting 50 consecutive RC Aerobatics (Pattern) contests. In 2004
the Aeroguidance Society started preparing to commemorate this
milestone event.
One of the activities suggested at the first planning meeting was
to design, build, and fly a replica of the little blue airplane. This
sounded like a great idea, and we were fortunate to have an
experienced designer—Ken Maroni—in the club and as a member
of the committee. He had designed several successful models, and I
volunteered to build this one.
The airplane had to resemble the one on the club logo, with its
high thrustline, low and rounded wing, stabilizer, and fin tips. It had
to be a tail-dragger, and we wanted a model that could be flown
adequately with a .40 cu. in. engine.
It was not long before Ken presented his first draft of the design
at a committee meeting, and we knew we were on the way to an
exciting chapter in the long history of the Aeroguidance Society.
After several design review sessions between Ken and me to adjust
the fuselage profile and make some minor construction changes, it
was time to start building.
We had decided to design and build both a Class II (rudder,
elevator, and throttle) and a Class III (aileron, elevator, rudder, and
throttle) model. (The Class I and II designations come from early
Retro
An artist rendering inspired this
great 40-size sport model
02sig1.QXD 12/20/07 9:23 AM Page 16February 2008 17
Just one 1/4-20 bolt is needed to secure the wing. The aluminum
gear is good for rough fields.
A good technique for making sure the formers are properly
shaped before sheeting is to mark with Magic Marker and use a
sanding bar to rub down high spots.
The AGS Retro takes off for a demonstration flight at the 50th Annual Aeroguidance
Society Precision Aerobatics Contest.
The battery is near center with the receiver in the front of
the equipment compartment. The model balanced perfectly
with this arrangement.
A Sig Four-Star 1.20 (kit RC65) canopy was trimmed to a pleasing fit. It
houses a doll bust from the local craft store.
AMA Pattern competition classes, when the
class that was flown depended on the
controls that were used. Class I was flown
with rudder and throttle control only.) Why
would we want to do this?
When the Aeroguidance Society was
formed in 1954, few RC airplanes had
ailerons. The one on the club logo didn’t; it
had a large dihedral angle, which was
necessary if ailerons were not going to be
used.
To be authentic we decided that the little
blue airplane should certainly be built
without ailerons, but we recognized that
most of today’s modelers would prefer to
have ailerons on their model. To make it
simpler for me, as the builder, I would
construct one fuselage with two wings. It
sounded like a good plan!
Now for the good news/bad news part of
this story; first is the bad news. I built the
first airplane for Class II—the one without
ailerons. Ken had never designed a Class II
02sig1.QXD 12/20/07 9:32 AM Page 1718 MODEL AVIATION
The fuselage is built with 1/4-inch square trusses to keep its weight
low and a sheeted turtledeck to make the structure rigid.
The Thunder Tiger .46 proved to be more than ample power for
this model. The engine is tilted so the high thrustline can be
maintained.
The top of the fuselage is sheeted with 3/32 balsa. Make sure to
sand the formers so that the sheeting fits flush.
Left: The Retro is made using conventional
wood construction throughout. This sport
model has good precision potential.
Above: The tail-feather parts are built up
with 1/4 square balsa sticks that are
sheeted with a 1/16 balsa skin.
The shape of the wingtips reflects the design of the little blue
airplane on the club logo. A shaped laminate technique is used.
02sig1.QXD 12/20/07 11:15 AM Page 18February 2008 19
The Retro has a distinguished appearance in the air—just like the
little blue airplane on the Aeroguidance Society logo.
A single aileron servo connected to torque rods provides linkage
to the ailerons. There’s plenty of control authority.
Single pushrods are used for the rudder and the elevator. Fuel tubing keeps the clevises
closed, and a longer piece acts as a shock-absorbing steering linkage for the tail wheel.
aircraft since all his models had ailerons,
which is what most designers use today.
However, we knew that the little blue
airplane on the logo didn’t have ailerons.
And the way you overcome the lack of
ailerons is to increase the wing dihedral.
That seemed easy enough.
We learned by experience that there was
not enough dihedral in the wing, which led
to a hairy first flight. To this day I am not
sure how I managed to keep the airplane
from crashing; it didn’t fly with its wings
level from after the first turn until I managed
to straighten it out for a damage-free
landing. My many years of flying must have
caused me to reach instinctively without
having time to think about the situation I
was in.
Several club members witnessed that first
flight, and we spent roughly 10 minutes
reflecting on what had happened. The
dihedral was not enough to allow the rudder
to do its job of turning the model.
In fact, as I applied left rudder for that
first turn the darned airplane decided it
wanted to fly on its left side. Go figure that
one out!
Now for the good news. I immediately
went home and cut ailerons into the wing,
which took only a day, and went back to the
field for the test flight of the then-Class III
model. The next flight was great, with only a
few minor trim changes.
After that I was confident with the design
and performed most of the maneuvers in my
repertoire. Loops and Rolls were good, but I
was more impressed with the little blue
airplane’s ability to do clean Stall Turns,
Point Rolls, and Snap Rolls. I was happy,
especially after that first flight a few days
earlier.
The model made its public debut at the
Type: RC sport monoplane
Builder skill level: Basic
Pilot skill level: Intermediate
Wingspan: 62.25 inches
Wing area: 671.3 square inches
Length: 56 inches
Weight: 4-6 pounds
Wing loading (average): 17.6
ounces/square foot
Engine: .40-.46 two-stroke
Radio: Three to four channels with
three or four standard servos
Construction: Balsa/plywood
Covering/finish: Builder’s choice;
MonoKote was used
AGS Retro
50th Annual Aeroguidance Society Precision
Aerobatics Contest, which took place just a
few weeks after those test flights. The AGS
Retro, as it is now known, has become a
part of the club’s rich history. I never did
build another wing without ailerons. I am an
easy learner.
This model is something different for the
“they all look alike” crowd. Give it a try.
Following is Ken’s account of some of the
AGS Retro’s design parameters.
The CG location is between the 30% and
33% point of the wing chord. I started at
25%-30% for initial flight. The tail moment
is 31.84 inches based on one-quarter chord
of each flight surface (wing and stabilizer).
The wing area is 671 square inches and the
stabilizer is 157.8 square inches.
The wing airfoil is basically an NACA
2415 with a fellow modeler’s alterations.
02sig1.QXD 12/20/07 9:42 AM Page 1920 MODEL AVIATION
The modification is flat on the bottom of the
airfoil from the 20% point to make it
possible to build on a flat surface without a
wing fixture. This airfoil has been used for
many models.
The fuselage was designed with a
laminated main fuselage body and truss
assembly for the empennage. The fuselage
lamination consists of light plywood as a
skeleton and a medium-grade balsa as the
laminate. This gives the fuselage body
strength and light weight. The truss
empennage section is integrated into the
main body of the fuselage to aid in strength
and distribution of moment forces.
The fuselage formers, landing-gear
mount plate, fuel-tank floor, and firewall are
notched to interlock with the fuselage sides
and associated formers. The engine firewall
has 2° of offset and is integrated as part of
the fuselage side construction.
The wing is of standard D-tube
construction with shear webs, planking on
the TE, and rib capstrips. The wing halves
are assembled using a dihedral brace that
ties the upper and lower spars together. The
brace also gives the wing its required
dihedral angle. The LE is formed by two
pieces of stick balsa glued together and
shaped to the LE radius. This technique
makes for an extremely strong assembly.
The tail feathers are of stick construction
and are sheeted with balsa.
The engine is mounted at a 45° angle to
create a clean, sleek appearance, with the
muffler tucked in close to the fuselage side.
Many of the accessories, such as the
canopy, landing gear, and tail wheel, are
common parts you can purchase through
Internet distributors or hobby shops. The
servos and flight-surface control
components, including the linkages, are
sized to suit a standard 40-size model.
The AGS Retro’s construction is simple
and straightforward. No special building
techniques are required, which makes this
project enjoyable for all levels of
pilots/builders. MA
Bob Noll
[email protected]
Ken Maroni
[email protected]
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02sig1.QXD 12/20/07 11:22 AM Page 20