July 2004 95
Paul Bradley
S m a l l - F i e l d F l y i n g
32238 Spinnaker Run, Magnolia TX 77354; E-mail: [email protected]
THE MARCH 2004 issue of Model Aviation is on my desk as I
am writing this column. One article in it that strikes my fancy is
“Electric Flash” by Harry Stewart. Talk about being up the smallfield-
flyer alley!
What is especially interesting is the inspiration for the model:
an old Comet rubber-powered Free Flight design. Reviewing
Harry’s construction article made me think that examining vintage
model-airplane designs—especially old rubber-powered Free
Flight models—would be a good topic for this forum.
The idea of using vintage designs for modern RC models is
certainly far from being a new concept. There are many more
examples than I could possibly list here. What leads me to open
this topic of discussion is the selection of models for good smallfield
flyers.
Regardless of our choice of power systems, some designs seem
to work much better than others when we include an ability to
control the model from the ground. Good Free Flight designs,
especially sport models, follow design parameters that give them
positive inherent stability.
They are lightly loaded, so features such as long, pointed wings
do not represent any real issues. Rubber-powered models often
have fairly long nose moments to help keep them in balance when
loaded with a rubber motor. All of these features work well for the
intended designs; however, moving those designs to the realm of
an engine- or electric motor-powered RC model can present some
interesting problems.
Models designed in the 1930s and 1940s provide some
appealing subjects. Highly tapered wings were typical of that era.
In fact, the Comet Flash used by Harry Stewart has this
characteristic. Wings with a lot of taper tend to tip-stall when
maneuvered.
For a Free Flight model flying in gentle circles with its light
This vintage Rubber Free Flight Comet Phantom Fury can be
modified as a Radio Control small-field-flyer design.
Bob Aberle’s Sioux is an RC small-field flyer based on a classic
powered Free Flight design by Joe Wagner.
Free Flight catapult-launched gliders such as this 404 Interceptor
convert well to RC small-field flyers.
wing loading, tip-stalling is not an issue. When we start
controlling the model from the ground and add the weight of an
internal-combustion engine or electric motor and radio gear, the
picture begins to change. A tip stall can raise its ugly head and bite
us if we are not careful. I was reminded of this fact with one of my
own projects.
Several years ago, before some of the current crop of
07sig3.QXD 4/23/04 1:07 pm Page 95
96 MODEL AVIATION
lightweight radio gear became available, I
decided to convert a Comet Phantom Fury
to an electric-powered RC model. (Another
rubber-powered Free Flight Comet used as
a source model. The prolific offerings from
the defunct Comet Models are a great
resource for developing small-field RC
models.)
The Phantom Fury is a perfect size for
small-field flying. With a wingspan of 32
inches and a generous fuselage crosssection,
this 1930s design looked to be
ideal.
The Phantom Fury has a highly tapered
wing planform with an area that is roughly
94 square inches. The flying weight of my
RC version is 4 ounces, giving it a wing
loading of 6.2 ounces per square foot. That
is a great value for a gentle-flying, smallfield
model.
After evaluating the numbers, I was
expecting a well-behaved model that would
yield many hours of relaxed small-field
flying. Early flights confirmed that the
model was a keeper, but it did display a
strong tendency to tip-stall if I applied
anything more than the most gentle rudder
input. The combination of the highly
tapered wing and the increased wing
loading from the Free Flight configuration showed up in spades.
The lighter equipment available today and the use of Li-Poly
cells in place of the Ni-Cd pack would help reduce the flying
weight of the model. Adding some washout to the tips (making the
TE higher than the LE) would also help tame the tip-stalling
characteristic.
Pay attention to wing planform if you are thinking of basing a
new small-field-flyer design on one of the great old vintage
models. Adding some washout to the tips will really help the
model to be a fun flyer rather than one prone to extract sweat and
tears on each flight.
Another factor to consider is the length of the nose, especially
if you are using a vintage rubber-powered model as the source of
your design. The original models had weight in the rubber motor
located behind the model’s CG. The weight of the propeller and a
long nose kept things in balance.
When the rubber motor is removed, the model’s CG quickly
moves forward. Replacing the lightweight Free Flight propeller
with an engine- or motor-driven propeller makes the CG move
forward even more. This means you need to plan to locate things
Author’s fleet of Top Flite Jigtime jet catapult-launched small-field flyers.
Built by Martin Hunter, the Mountain Models Flashback is a builtup-
kit Pattern small-field flyer.
Jeff Carr’s Fliton USA Jumping Jack comes as an ARF and is
another small-field, Pattern-type model.
such as batteries and servos toward the rear of the area
encompassed by the wing.
Make sure the source model has enough area in the fuselage to
allow for equipment installation farther to the rear. Most do, but it
does not hurt to consider that factor in the beginning.
Considering long nose moments for rubber-powered Free Flight
designs, the converse is true for vintage-engine-powered models.
These had relatively short nose moments. Generally, that makes
today’s small-field-flyer conversion fairly simple.
Where we sometimes get into trouble is the typical long tail
moment. The Free Flight configuration worked nicely because no
heavy components existed between the CG and the tail—at least
this is the case for glow-powered models.
When we convert vintage power models to RC flyers, we load
them down with radio gear and batteries. The short nose moment
makes it difficult to place these components ahead of the CG.
Servos often end up aft of the CG, and suddenly you end up with a
tail-heavy model rather than one that is nose-heavy.
When looking at vintage-power-model designs, take a look at
the space between the engine firewall and the model’s CG. Will
07sig3.QXD 4/23/04 1:08 pm Page 96
98 MODEL AVIATION
that space allow you to place any of the
heavier equipment such as batteries in that
area?
A great powered Free Flight model gone
RC small-field flyer is one of Bob Aberle’s
projects. He converted a classic design by Joe
Wagner called The Sioux.
The Sioux was kitted by the now defunct
Veco. Bob’s model has a 27-inch wingspan
and is electric powered. A complete
construction article for Bob’s model is in the
April 2004 issue of Quiet Flyer. The source
list at the end of the column has plansordering
information.
These are only a few parameters to think
about when planning to build a modern smallfield
flyer based on a vintage Free Flight
design.
A few columns ago I addressed the subject of
powered gliders in the arena of small-field
flying. An area that I did not venture into is
the possibility of nonpowered gliders in the
small-field venue.
In this category we naturally think of RC
hand-launched gliders. While these models
can be flown in smaller fields, they are more
typically flown in spaces that will allow some
long thermal-duration flights—at least, that is
my perspective. I have flown the gliders in
very small spaces, but my flying was limited
to launching practice followed by a shortduration
return flight.
I want to explore another type of Free
Flight model—namely the catapult-launched
glider. These models are launched with a loop
of rubber tied to a stick, similar to a slingshot.
They go straight up and are capable of long
flights. This means they are typically flown in
larger fields.
What if we added some of the emerging
micro RC gear and stuck a transmitter in our
hand? The catapult-launched glider could
then be kept inside the perimeter of our
chosen small field. We could even milk a
little lift and still keep things close in.
I am in the process of developing two
different catapult gliders for my local small
field. The first is based on a great vintage Free
Flight design. You may be familiar with the
old American Junior 404 Interceptor foldingwing
glider. These models were developed by
Jim Walker in the 1940s and have always
been popular with modelers.
The original American Junior Company
(AJ) is long gone, but we are fortunate to
have the great AJ models available through
reproductions. The line is currently being
reproduced by Frank Macy of McMinnville,
Oregon (see source listing). His products are
first class. I am converting the 404 Interceptor
shown in the picture to RC. I will report on
my results in the next column.
The great AJ Interceptor is one approach
to developing a small-field RC catapultlaunched
glider. I have another project in the
works based on the scale jet catapult gliders
that were offered by Top Flite in its Jigtime
series. With wingspans in the 8- to 9-inch
range, they are perfect for flying in small
spaces—as long as you can keep them in
bounds. That is where we apply some more of
the great micro gear that we read about in
Dave Robelen’s Model Aviation column.
What fun! A folding-wing glider and a
scale jet glider! In case you have not seen any
of the old Top Flite catapult jet gliders, I have
included a photo of my reproduction fleet. I
will report on my ventures with the Top Flite
catapult jet models in a future column.
All of my Jigtime reproduction models
including the jets are available for free
download from my Web site at
www.parmodels.com.
Now that I have languished in vintage Free
Flight land, I’ll switch gears to some new
offerings. Several columns back, I wrote
about the world of 3-D aerobatic models in
the small-field world. Many great airplanes
are becoming available that offer exceptional
performance.
Looking at the different extreme 3-D
aircraft that are on the market, I wondered if
something with more traditional Pattern
model lines might be practical for our venue.
The 3-D models tend to be short coupled
to perform the really tight maneuvers. Pattern
models show longer tail moments and design
features intended for large, smooth
maneuvers.
Based on recent offerings from the
manufacturers, it looks as if the Pattern-type
model has arrived on the small-field-flyer
scene. They come in the form of build-fromparts
kits to nice ARF models. The
manufacturers have covered the different
levels of interest from hobby participants.
A good build-from-parts kit is the
Mountain Models Flashback. It has all of
those Pattern model lines and flight
characteristics. A review by Martin Hunter is
located on the E Zone at www.rcgroups.com/
links/index.php?id=4345.
If you would prefer an ARF, a nice kit is
the Jumping Jack from Fliton Models. Similar
to the Flashback, the Jumping Jack has the
look and performance of a traditional Pattern
model. Jeff Carr has written a comprehensive
review located on the E Zone at www.rc
groups.com/links/index.php?id=4347.
I have included photos of both models to
give you an idea of what is new in the form of
small-field Pattern models.
Here we are again at the close of the column.
My mailbag—electronic and regular—has
been empty for a while; please don’t be
bashful about sending me some pictures and
descriptions of your small-field modeling
projects. MA
Sources:
Bob Aberle’s Sioux:
Kiona Publishing
(866) 627-0456
www.kionapublishing.com
AJ 404 Interceptor:
Frank Macy
1501 SW Baker St. #53
McMinnville OR 97128
(503) 435-1916
[email protected]
Flashback:
Mountain Models
Box 762
Penrose CO 81240
(719) 372-6727
www.mountainmodels.com
Jumping Jack:
Fliton USA
4790 Irvine Blvd. Suite 105/229
Irvine CA 92620
(888) 473-0856
www.fliton.com
6x3 . . . . $
6.5x4 . . . .
7x4 . . . . . .
7.5x5 . . . .
8x4 . . . . . .
8x5 . . . . . .
8.5x5 . . . .
9x6 . . . . . .
10x7 . . . . .
10x8 . . . . .
11x7 . . . . .
12x8 . . . . .
13x8.5 . . .
1.50
1.50
1.50
1.50
2.25
2.25
2.25
2.45
2.95
2.95
3.25
3.45
3.95
•Ultra lightweight
•Thin, flexible design
•Undercambered blades
•Superior performance
•Made of glass-filled nylon
Windsor Propeller Co. Inc.
www.masterairscrew.com
voice 916-631-8385
ELECTRIC ONLY SERIES
SIZES MASTER AIRSCREW
AM
A
07sig4.QXD 4/23/04 12:37 pm Page 98
Edition: Model Aviation - 2004/07
Page Numbers: 95,96,98
Edition: Model Aviation - 2004/07
Page Numbers: 95,96,98
July 2004 95
Paul Bradley
S m a l l - F i e l d F l y i n g
32238 Spinnaker Run, Magnolia TX 77354; E-mail: [email protected]
THE MARCH 2004 issue of Model Aviation is on my desk as I
am writing this column. One article in it that strikes my fancy is
“Electric Flash” by Harry Stewart. Talk about being up the smallfield-
flyer alley!
What is especially interesting is the inspiration for the model:
an old Comet rubber-powered Free Flight design. Reviewing
Harry’s construction article made me think that examining vintage
model-airplane designs—especially old rubber-powered Free
Flight models—would be a good topic for this forum.
The idea of using vintage designs for modern RC models is
certainly far from being a new concept. There are many more
examples than I could possibly list here. What leads me to open
this topic of discussion is the selection of models for good smallfield
flyers.
Regardless of our choice of power systems, some designs seem
to work much better than others when we include an ability to
control the model from the ground. Good Free Flight designs,
especially sport models, follow design parameters that give them
positive inherent stability.
They are lightly loaded, so features such as long, pointed wings
do not represent any real issues. Rubber-powered models often
have fairly long nose moments to help keep them in balance when
loaded with a rubber motor. All of these features work well for the
intended designs; however, moving those designs to the realm of
an engine- or electric motor-powered RC model can present some
interesting problems.
Models designed in the 1930s and 1940s provide some
appealing subjects. Highly tapered wings were typical of that era.
In fact, the Comet Flash used by Harry Stewart has this
characteristic. Wings with a lot of taper tend to tip-stall when
maneuvered.
For a Free Flight model flying in gentle circles with its light
This vintage Rubber Free Flight Comet Phantom Fury can be
modified as a Radio Control small-field-flyer design.
Bob Aberle’s Sioux is an RC small-field flyer based on a classic
powered Free Flight design by Joe Wagner.
Free Flight catapult-launched gliders such as this 404 Interceptor
convert well to RC small-field flyers.
wing loading, tip-stalling is not an issue. When we start
controlling the model from the ground and add the weight of an
internal-combustion engine or electric motor and radio gear, the
picture begins to change. A tip stall can raise its ugly head and bite
us if we are not careful. I was reminded of this fact with one of my
own projects.
Several years ago, before some of the current crop of
07sig3.QXD 4/23/04 1:07 pm Page 95
96 MODEL AVIATION
lightweight radio gear became available, I
decided to convert a Comet Phantom Fury
to an electric-powered RC model. (Another
rubber-powered Free Flight Comet used as
a source model. The prolific offerings from
the defunct Comet Models are a great
resource for developing small-field RC
models.)
The Phantom Fury is a perfect size for
small-field flying. With a wingspan of 32
inches and a generous fuselage crosssection,
this 1930s design looked to be
ideal.
The Phantom Fury has a highly tapered
wing planform with an area that is roughly
94 square inches. The flying weight of my
RC version is 4 ounces, giving it a wing
loading of 6.2 ounces per square foot. That
is a great value for a gentle-flying, smallfield
model.
After evaluating the numbers, I was
expecting a well-behaved model that would
yield many hours of relaxed small-field
flying. Early flights confirmed that the
model was a keeper, but it did display a
strong tendency to tip-stall if I applied
anything more than the most gentle rudder
input. The combination of the highly
tapered wing and the increased wing
loading from the Free Flight configuration showed up in spades.
The lighter equipment available today and the use of Li-Poly
cells in place of the Ni-Cd pack would help reduce the flying
weight of the model. Adding some washout to the tips (making the
TE higher than the LE) would also help tame the tip-stalling
characteristic.
Pay attention to wing planform if you are thinking of basing a
new small-field-flyer design on one of the great old vintage
models. Adding some washout to the tips will really help the
model to be a fun flyer rather than one prone to extract sweat and
tears on each flight.
Another factor to consider is the length of the nose, especially
if you are using a vintage rubber-powered model as the source of
your design. The original models had weight in the rubber motor
located behind the model’s CG. The weight of the propeller and a
long nose kept things in balance.
When the rubber motor is removed, the model’s CG quickly
moves forward. Replacing the lightweight Free Flight propeller
with an engine- or motor-driven propeller makes the CG move
forward even more. This means you need to plan to locate things
Author’s fleet of Top Flite Jigtime jet catapult-launched small-field flyers.
Built by Martin Hunter, the Mountain Models Flashback is a builtup-
kit Pattern small-field flyer.
Jeff Carr’s Fliton USA Jumping Jack comes as an ARF and is
another small-field, Pattern-type model.
such as batteries and servos toward the rear of the area
encompassed by the wing.
Make sure the source model has enough area in the fuselage to
allow for equipment installation farther to the rear. Most do, but it
does not hurt to consider that factor in the beginning.
Considering long nose moments for rubber-powered Free Flight
designs, the converse is true for vintage-engine-powered models.
These had relatively short nose moments. Generally, that makes
today’s small-field-flyer conversion fairly simple.
Where we sometimes get into trouble is the typical long tail
moment. The Free Flight configuration worked nicely because no
heavy components existed between the CG and the tail—at least
this is the case for glow-powered models.
When we convert vintage power models to RC flyers, we load
them down with radio gear and batteries. The short nose moment
makes it difficult to place these components ahead of the CG.
Servos often end up aft of the CG, and suddenly you end up with a
tail-heavy model rather than one that is nose-heavy.
When looking at vintage-power-model designs, take a look at
the space between the engine firewall and the model’s CG. Will
07sig3.QXD 4/23/04 1:08 pm Page 96
98 MODEL AVIATION
that space allow you to place any of the
heavier equipment such as batteries in that
area?
A great powered Free Flight model gone
RC small-field flyer is one of Bob Aberle’s
projects. He converted a classic design by Joe
Wagner called The Sioux.
The Sioux was kitted by the now defunct
Veco. Bob’s model has a 27-inch wingspan
and is electric powered. A complete
construction article for Bob’s model is in the
April 2004 issue of Quiet Flyer. The source
list at the end of the column has plansordering
information.
These are only a few parameters to think
about when planning to build a modern smallfield
flyer based on a vintage Free Flight
design.
A few columns ago I addressed the subject of
powered gliders in the arena of small-field
flying. An area that I did not venture into is
the possibility of nonpowered gliders in the
small-field venue.
In this category we naturally think of RC
hand-launched gliders. While these models
can be flown in smaller fields, they are more
typically flown in spaces that will allow some
long thermal-duration flights—at least, that is
my perspective. I have flown the gliders in
very small spaces, but my flying was limited
to launching practice followed by a shortduration
return flight.
I want to explore another type of Free
Flight model—namely the catapult-launched
glider. These models are launched with a loop
of rubber tied to a stick, similar to a slingshot.
They go straight up and are capable of long
flights. This means they are typically flown in
larger fields.
What if we added some of the emerging
micro RC gear and stuck a transmitter in our
hand? The catapult-launched glider could
then be kept inside the perimeter of our
chosen small field. We could even milk a
little lift and still keep things close in.
I am in the process of developing two
different catapult gliders for my local small
field. The first is based on a great vintage Free
Flight design. You may be familiar with the
old American Junior 404 Interceptor foldingwing
glider. These models were developed by
Jim Walker in the 1940s and have always
been popular with modelers.
The original American Junior Company
(AJ) is long gone, but we are fortunate to
have the great AJ models available through
reproductions. The line is currently being
reproduced by Frank Macy of McMinnville,
Oregon (see source listing). His products are
first class. I am converting the 404 Interceptor
shown in the picture to RC. I will report on
my results in the next column.
The great AJ Interceptor is one approach
to developing a small-field RC catapultlaunched
glider. I have another project in the
works based on the scale jet catapult gliders
that were offered by Top Flite in its Jigtime
series. With wingspans in the 8- to 9-inch
range, they are perfect for flying in small
spaces—as long as you can keep them in
bounds. That is where we apply some more of
the great micro gear that we read about in
Dave Robelen’s Model Aviation column.
What fun! A folding-wing glider and a
scale jet glider! In case you have not seen any
of the old Top Flite catapult jet gliders, I have
included a photo of my reproduction fleet. I
will report on my ventures with the Top Flite
catapult jet models in a future column.
All of my Jigtime reproduction models
including the jets are available for free
download from my Web site at
www.parmodels.com.
Now that I have languished in vintage Free
Flight land, I’ll switch gears to some new
offerings. Several columns back, I wrote
about the world of 3-D aerobatic models in
the small-field world. Many great airplanes
are becoming available that offer exceptional
performance.
Looking at the different extreme 3-D
aircraft that are on the market, I wondered if
something with more traditional Pattern
model lines might be practical for our venue.
The 3-D models tend to be short coupled
to perform the really tight maneuvers. Pattern
models show longer tail moments and design
features intended for large, smooth
maneuvers.
Based on recent offerings from the
manufacturers, it looks as if the Pattern-type
model has arrived on the small-field-flyer
scene. They come in the form of build-fromparts
kits to nice ARF models. The
manufacturers have covered the different
levels of interest from hobby participants.
A good build-from-parts kit is the
Mountain Models Flashback. It has all of
those Pattern model lines and flight
characteristics. A review by Martin Hunter is
located on the E Zone at www.rcgroups.com/
links/index.php?id=4345.
If you would prefer an ARF, a nice kit is
the Jumping Jack from Fliton Models. Similar
to the Flashback, the Jumping Jack has the
look and performance of a traditional Pattern
model. Jeff Carr has written a comprehensive
review located on the E Zone at www.rc
groups.com/links/index.php?id=4347.
I have included photos of both models to
give you an idea of what is new in the form of
small-field Pattern models.
Here we are again at the close of the column.
My mailbag—electronic and regular—has
been empty for a while; please don’t be
bashful about sending me some pictures and
descriptions of your small-field modeling
projects. MA
Sources:
Bob Aberle’s Sioux:
Kiona Publishing
(866) 627-0456
www.kionapublishing.com
AJ 404 Interceptor:
Frank Macy
1501 SW Baker St. #53
McMinnville OR 97128
(503) 435-1916
[email protected]
Flashback:
Mountain Models
Box 762
Penrose CO 81240
(719) 372-6727
www.mountainmodels.com
Jumping Jack:
Fliton USA
4790 Irvine Blvd. Suite 105/229
Irvine CA 92620
(888) 473-0856
www.fliton.com
6x3 . . . . $
6.5x4 . . . .
7x4 . . . . . .
7.5x5 . . . .
8x4 . . . . . .
8x5 . . . . . .
8.5x5 . . . .
9x6 . . . . . .
10x7 . . . . .
10x8 . . . . .
11x7 . . . . .
12x8 . . . . .
13x8.5 . . .
1.50
1.50
1.50
1.50
2.25
2.25
2.25
2.45
2.95
2.95
3.25
3.45
3.95
•Ultra lightweight
•Thin, flexible design
•Undercambered blades
•Superior performance
•Made of glass-filled nylon
Windsor Propeller Co. Inc.
www.masterairscrew.com
voice 916-631-8385
ELECTRIC ONLY SERIES
SIZES MASTER AIRSCREW
AM
A
07sig4.QXD 4/23/04 12:37 pm Page 98
Edition: Model Aviation - 2004/07
Page Numbers: 95,96,98
July 2004 95
Paul Bradley
S m a l l - F i e l d F l y i n g
32238 Spinnaker Run, Magnolia TX 77354; E-mail: [email protected]
THE MARCH 2004 issue of Model Aviation is on my desk as I
am writing this column. One article in it that strikes my fancy is
“Electric Flash” by Harry Stewart. Talk about being up the smallfield-
flyer alley!
What is especially interesting is the inspiration for the model:
an old Comet rubber-powered Free Flight design. Reviewing
Harry’s construction article made me think that examining vintage
model-airplane designs—especially old rubber-powered Free
Flight models—would be a good topic for this forum.
The idea of using vintage designs for modern RC models is
certainly far from being a new concept. There are many more
examples than I could possibly list here. What leads me to open
this topic of discussion is the selection of models for good smallfield
flyers.
Regardless of our choice of power systems, some designs seem
to work much better than others when we include an ability to
control the model from the ground. Good Free Flight designs,
especially sport models, follow design parameters that give them
positive inherent stability.
They are lightly loaded, so features such as long, pointed wings
do not represent any real issues. Rubber-powered models often
have fairly long nose moments to help keep them in balance when
loaded with a rubber motor. All of these features work well for the
intended designs; however, moving those designs to the realm of
an engine- or electric motor-powered RC model can present some
interesting problems.
Models designed in the 1930s and 1940s provide some
appealing subjects. Highly tapered wings were typical of that era.
In fact, the Comet Flash used by Harry Stewart has this
characteristic. Wings with a lot of taper tend to tip-stall when
maneuvered.
For a Free Flight model flying in gentle circles with its light
This vintage Rubber Free Flight Comet Phantom Fury can be
modified as a Radio Control small-field-flyer design.
Bob Aberle’s Sioux is an RC small-field flyer based on a classic
powered Free Flight design by Joe Wagner.
Free Flight catapult-launched gliders such as this 404 Interceptor
convert well to RC small-field flyers.
wing loading, tip-stalling is not an issue. When we start
controlling the model from the ground and add the weight of an
internal-combustion engine or electric motor and radio gear, the
picture begins to change. A tip stall can raise its ugly head and bite
us if we are not careful. I was reminded of this fact with one of my
own projects.
Several years ago, before some of the current crop of
07sig3.QXD 4/23/04 1:07 pm Page 95
96 MODEL AVIATION
lightweight radio gear became available, I
decided to convert a Comet Phantom Fury
to an electric-powered RC model. (Another
rubber-powered Free Flight Comet used as
a source model. The prolific offerings from
the defunct Comet Models are a great
resource for developing small-field RC
models.)
The Phantom Fury is a perfect size for
small-field flying. With a wingspan of 32
inches and a generous fuselage crosssection,
this 1930s design looked to be
ideal.
The Phantom Fury has a highly tapered
wing planform with an area that is roughly
94 square inches. The flying weight of my
RC version is 4 ounces, giving it a wing
loading of 6.2 ounces per square foot. That
is a great value for a gentle-flying, smallfield
model.
After evaluating the numbers, I was
expecting a well-behaved model that would
yield many hours of relaxed small-field
flying. Early flights confirmed that the
model was a keeper, but it did display a
strong tendency to tip-stall if I applied
anything more than the most gentle rudder
input. The combination of the highly
tapered wing and the increased wing
loading from the Free Flight configuration showed up in spades.
The lighter equipment available today and the use of Li-Poly
cells in place of the Ni-Cd pack would help reduce the flying
weight of the model. Adding some washout to the tips (making the
TE higher than the LE) would also help tame the tip-stalling
characteristic.
Pay attention to wing planform if you are thinking of basing a
new small-field-flyer design on one of the great old vintage
models. Adding some washout to the tips will really help the
model to be a fun flyer rather than one prone to extract sweat and
tears on each flight.
Another factor to consider is the length of the nose, especially
if you are using a vintage rubber-powered model as the source of
your design. The original models had weight in the rubber motor
located behind the model’s CG. The weight of the propeller and a
long nose kept things in balance.
When the rubber motor is removed, the model’s CG quickly
moves forward. Replacing the lightweight Free Flight propeller
with an engine- or motor-driven propeller makes the CG move
forward even more. This means you need to plan to locate things
Author’s fleet of Top Flite Jigtime jet catapult-launched small-field flyers.
Built by Martin Hunter, the Mountain Models Flashback is a builtup-
kit Pattern small-field flyer.
Jeff Carr’s Fliton USA Jumping Jack comes as an ARF and is
another small-field, Pattern-type model.
such as batteries and servos toward the rear of the area
encompassed by the wing.
Make sure the source model has enough area in the fuselage to
allow for equipment installation farther to the rear. Most do, but it
does not hurt to consider that factor in the beginning.
Considering long nose moments for rubber-powered Free Flight
designs, the converse is true for vintage-engine-powered models.
These had relatively short nose moments. Generally, that makes
today’s small-field-flyer conversion fairly simple.
Where we sometimes get into trouble is the typical long tail
moment. The Free Flight configuration worked nicely because no
heavy components existed between the CG and the tail—at least
this is the case for glow-powered models.
When we convert vintage power models to RC flyers, we load
them down with radio gear and batteries. The short nose moment
makes it difficult to place these components ahead of the CG.
Servos often end up aft of the CG, and suddenly you end up with a
tail-heavy model rather than one that is nose-heavy.
When looking at vintage-power-model designs, take a look at
the space between the engine firewall and the model’s CG. Will
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98 MODEL AVIATION
that space allow you to place any of the
heavier equipment such as batteries in that
area?
A great powered Free Flight model gone
RC small-field flyer is one of Bob Aberle’s
projects. He converted a classic design by Joe
Wagner called The Sioux.
The Sioux was kitted by the now defunct
Veco. Bob’s model has a 27-inch wingspan
and is electric powered. A complete
construction article for Bob’s model is in the
April 2004 issue of Quiet Flyer. The source
list at the end of the column has plansordering
information.
These are only a few parameters to think
about when planning to build a modern smallfield
flyer based on a vintage Free Flight
design.
A few columns ago I addressed the subject of
powered gliders in the arena of small-field
flying. An area that I did not venture into is
the possibility of nonpowered gliders in the
small-field venue.
In this category we naturally think of RC
hand-launched gliders. While these models
can be flown in smaller fields, they are more
typically flown in spaces that will allow some
long thermal-duration flights—at least, that is
my perspective. I have flown the gliders in
very small spaces, but my flying was limited
to launching practice followed by a shortduration
return flight.
I want to explore another type of Free
Flight model—namely the catapult-launched
glider. These models are launched with a loop
of rubber tied to a stick, similar to a slingshot.
They go straight up and are capable of long
flights. This means they are typically flown in
larger fields.
What if we added some of the emerging
micro RC gear and stuck a transmitter in our
hand? The catapult-launched glider could
then be kept inside the perimeter of our
chosen small field. We could even milk a
little lift and still keep things close in.
I am in the process of developing two
different catapult gliders for my local small
field. The first is based on a great vintage Free
Flight design. You may be familiar with the
old American Junior 404 Interceptor foldingwing
glider. These models were developed by
Jim Walker in the 1940s and have always
been popular with modelers.
The original American Junior Company
(AJ) is long gone, but we are fortunate to
have the great AJ models available through
reproductions. The line is currently being
reproduced by Frank Macy of McMinnville,
Oregon (see source listing). His products are
first class. I am converting the 404 Interceptor
shown in the picture to RC. I will report on
my results in the next column.
The great AJ Interceptor is one approach
to developing a small-field RC catapultlaunched
glider. I have another project in the
works based on the scale jet catapult gliders
that were offered by Top Flite in its Jigtime
series. With wingspans in the 8- to 9-inch
range, they are perfect for flying in small
spaces—as long as you can keep them in
bounds. That is where we apply some more of
the great micro gear that we read about in
Dave Robelen’s Model Aviation column.
What fun! A folding-wing glider and a
scale jet glider! In case you have not seen any
of the old Top Flite catapult jet gliders, I have
included a photo of my reproduction fleet. I
will report on my ventures with the Top Flite
catapult jet models in a future column.
All of my Jigtime reproduction models
including the jets are available for free
download from my Web site at
www.parmodels.com.
Now that I have languished in vintage Free
Flight land, I’ll switch gears to some new
offerings. Several columns back, I wrote
about the world of 3-D aerobatic models in
the small-field world. Many great airplanes
are becoming available that offer exceptional
performance.
Looking at the different extreme 3-D
aircraft that are on the market, I wondered if
something with more traditional Pattern
model lines might be practical for our venue.
The 3-D models tend to be short coupled
to perform the really tight maneuvers. Pattern
models show longer tail moments and design
features intended for large, smooth
maneuvers.
Based on recent offerings from the
manufacturers, it looks as if the Pattern-type
model has arrived on the small-field-flyer
scene. They come in the form of build-fromparts
kits to nice ARF models. The
manufacturers have covered the different
levels of interest from hobby participants.
A good build-from-parts kit is the
Mountain Models Flashback. It has all of
those Pattern model lines and flight
characteristics. A review by Martin Hunter is
located on the E Zone at www.rcgroups.com/
links/index.php?id=4345.
If you would prefer an ARF, a nice kit is
the Jumping Jack from Fliton Models. Similar
to the Flashback, the Jumping Jack has the
look and performance of a traditional Pattern
model. Jeff Carr has written a comprehensive
review located on the E Zone at www.rc
groups.com/links/index.php?id=4347.
I have included photos of both models to
give you an idea of what is new in the form of
small-field Pattern models.
Here we are again at the close of the column.
My mailbag—electronic and regular—has
been empty for a while; please don’t be
bashful about sending me some pictures and
descriptions of your small-field modeling
projects. MA
Sources:
Bob Aberle’s Sioux:
Kiona Publishing
(866) 627-0456
www.kionapublishing.com
AJ 404 Interceptor:
Frank Macy
1501 SW Baker St. #53
McMinnville OR 97128
(503) 435-1916
[email protected]
Flashback:
Mountain Models
Box 762
Penrose CO 81240
(719) 372-6727
www.mountainmodels.com
Jumping Jack:
Fliton USA
4790 Irvine Blvd. Suite 105/229
Irvine CA 92620
(888) 473-0856
www.fliton.com
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