Variable-pitch propellers explained
July 2006 129
Also included in this column:
• New Winning Indoor Designs
book
• What constitutes a good
beginner’s event?
• The Chicago Indoor FF scene
• Newsletter of the month
Free Flight Indoor John Kagan
[[email protected]]
Bernie Hunt’s neat VP uses Kevlar-thread hinges. He was recently awarded the
FAI/CIAM Antonov Diploma for technical innovation in modeling. Aikman photo.
Ray Harlan’s “inverted” VP features pass-through actuator
arms and a boron-reinforced hub.
The author’s VP mechanism is based on the long-standing Cezar
Banks design. The red washer is a ruby used for jeweled
wristwatches.
That’s not a bagel supporting reigning
Indoor FF National Cup champ Tom
Sova’s VP; it’s a Cheerio! Sova photo.
Dezso Orsovai’s VP has wonderful
craftsmanship. The whole mechanism is
only roughly 1/2 inch long. Aikman photo.
VARIABLE-PITCH PROPELLERS: In
the events that allow them, variable-geometry
propellers are a key competitive advantage.
Variable-pitch (VP) propellers are the most
common. There are many different VP styles
and designs, and each aims to improve
performance or increase durability compared
with the others in some way, but the
underlying principle is generally the same.
As commonly used, VP propeller hubs
change the pitch of the propeller blades in
response to the varying torque in the rubber
motor. At high motor torque the hub sets the
blades at a high pitch, reducing the amount of
thrust produced, keeping the model from
climbing into the ceiling. When the torque
decreases, the hub begins “closing,” reducing
the propeller pitch.
Some designs bang from high to low pitch
quickly, and others make the change
throughout a large portion of the flight.
Which is better? There are as many opinions
as there are designs. I prefer the slow-burn
approach. Just make sure the change doesn’t
take so long that you never reach full low
pitch.
At the low-pitch setting the propeller
generates more thrust at a given torque,
extending the flight and hopefully using all
the remaining energy in the motor. With
130 MODEL AVIATION
A Bong Eagles (named for its outdoor flying site: the Bong Recreational Area) mass
launch at Memorial Hall in Racine, Wisconsin. Nice flying site!
Bong Eagles members (L-R) Ivr Kovnat, Otto Curth, Kenny Krempetz, Joe Adamek,
Jack Boone, Jim Gerszewski, Jack Schnobrion, and Kurt Krempetz (kneeling).
fixed-pitch propellers, most people aim to
land with a partial row of knots in the
motor, but a VP will ideally land
completely dead-stick.
Many designs use devices such as
screws or shims to adjust variables such
as spring preload or the high- and lowpitch
stops. These kinds of hubs can be
quickly optimized for different ceiling
heights, specific motors, and even
temperature or humidity changes—a
distinct benefit in competition.
With a VP, instead of backing off
turns to control altitude or changing
motors to fine-tune the flight profile, you
can launch with full torque every time
and use a screwdriver to dial things in.
Look at the accompanying photos for
sampling of current designs. These VP
hubs are approximately .5 inch long and
weigh approximately .1 gram! A
challenge, to be sure, but certainly not
impossible to construct.
For a great VP tutorial, look at Steve
Brown’s article in Indoor News and
Views #89 or the “Articles” section of
Indoor Duration at www.indoorduration.
com. You can find more VP photos at
www.indoornews.com and http://groups.
yahoo.com/group/indoor_construction.
Winning Indoor Designs: You may
know about the 1987-1989 Winning
Indoor Designs book, published by the
National Free Flight Society (NFFS). It is
filled with top-notch Indoor FF plans for
every category, alongside descriptions
and building notes packed with
knowledge.
Most of the designs in the book are
still competitive, but the information is
approaching 20 years old. Furthermore,
the book is no longer in print, making it
that much harder to get your hands on a
copy.
Carl Bakay to the rescue! He has
laboriously assembled a modern collection
of record-setting and US Indoor
Championships (USIC)/Kibbie Domewinning
designs and notes that rivals its
predecessor. I’ve paged through a
preliminary copy and can attest to its
quality.
Whether you are into serious Indoor FF
competition or simply appreciate beauty of
top-level designs, this book is a must-have.
Winning Indoor Designs 2002-2005 is
available for $15 + $4.50 shipping and
handling from Bob Stalick, NFFS
Publications, Box 1775, Albany OR 97321;
E-mail: [email protected].
Making a Good “Beginner Class”: There
are a variety of objectives to choose from
when defining an Indoor FF class, such as
ultimate performance (such as Hand-
Launched Stick), a particular technical
challenge (Ornithopter, Autogiro, etc.), or a
design to fit special sites (such as
MiniStick, originally labeled Living Room
Stick).
One of the most common goals, though,
has been to devise an “easy” event that
would be more accessible to beginners than
the sophisticated classes, with the intent to
attract new participants.
Every so often a familiar-sounding
debate resurfaces regarding one of these
beginner events. Some aspect of the class
has evolved to the point where it is now
hard to be competitive, undermining the
original intent.
EZB has become the ultimate test of
strength vs. weight wood selection, with its
bracing prohibition and lack of a minimum
weight limit. Despite a relatively high
minimum weight, Pennyplane is now an
expert challenge, with biplane
configurations, short coupling, and long
motors on short motorsticks. Bostonian
esigns now commonly employ lifting body
configurations (offending realism purists),
sizes that make the 7-gram target difficult,
and stability-reducing full-body-length
motors.
In response, additional rules that reign in
these areas are proposed, often producing
new classes. F1L—the international version
of US EZB—has a 1.2-gram minimum
weight, making wood selection less critical.
Limited Pennyplane has restrictions on wing
and stabilizer dimensions and is limited to
monoplanes—changes that drastically
improve pitch stability and reduce
complexity.
The most advanced classes have the
fewest rules, and the simplest classes have
the most rules. However, the extra
restrictions are deemed necessary to keep
complexity under control and keep the event
accessible to beginners.
Accessibility is the key point. A certain
construction requirement might not be the
easiest (such as paper covering vs. plastic),
but it should be reasonably obtainable by a
beginner (as opposed to microfilm, for
instance).
Rules that define a successful beginner’s
event have been created several times, but
an area of newcomer acquisition that is
rarely adequately addressed is the definition
of a beginning level of competition
accomplishment. Many beginner events
impose restrictions that hope to keep
newcomers competitive with the experts.
It’s a nice thought, but it has repeatedly
been shown to be unrealistic.
The experts inevitably push the limits of
the design and eek out that small extra
advantage. If success in competition is a
requirement for retaining newcomers (an
assertion that I do not necessarily agree
with), it is unlikely to happen when they are
paired against the veterans.
There has been some discussion in the
Indoor FF community about how to define an
event that separates the newcomers from the
experts, giving beginners a chance to taste
success. Some suggest a handicap system,
similar to that in golf. Others offer tiered
groupings, such as the Sportsman,
Intermediate, Advanced, and Masters classes
in RC Aerobatics. I propose performance
achievement(s)—six minutes with a Limited
Pennyplane, for instance—modeled after RC
Soaring League of Silent Flight levels.
Whatever “recipe for newcomers” people
endorse, we at least all recognize the
importance of sharing our passion. Our
methods may differ, but we love Indoor FF
and want others to experience it too!
If you are interested in discussing Indoor
FF-related topics, consider joining the
various Indoor forums at www.indoor
news.com, http://groups.yahoo.com/
group/indoor_construction, and www.small
flyingarts.com.
Chicago “Local Scene”: Top-level Indoor
Glider competitor Kurt Krempetz sent in the
following report on Indoor FF activity in his
hometown area of Chicago, Illinois:
“There are many clubs that have worked
hard to promote Indoor Free Flight around
Chicago, Illinois. One is the Bong Eagles,
which meets in Milwaukee, Wisconsin.
Typically, the first Thursday evening of
every month they sponsor a Fun-Fly at
Memorial Hall in Racine, Wisconsin. I’ve
included a picture of the group of great guys
who were present in March.
“Twice a year the Bong Eagles holds a
Spring and Fall Indoor Contest for an entire
Sunday. Year after year Jack Boone, Joe
Adams, and Joe Adamek do an excellent job
running the contests. Other notable legends
who are members of the Bong Eagles are
Tony Italiano and Gordy Wisnewski, who
are typically at the Sunday contests helping
others.
“Another club that has worked hard
promoting Indoor Free Flight is the Chicago
Aeronuts. For many years Bob Warmann
has been the Contest Director of the Annual
Midwest Championships.
“Bob has done an excellent job
organizing and running the contest along
with being a fierce competitor. For the last
few years the Chicago Aeronuts has held
this event in the Armory at the University of
Illinois—a good Category III site. Notable
legends who are members of the Chicago
Aeronuts are Chuck Markos and Ed
Konefes.
“If you are interested in Indoor Freefamily’s Glider Web site at www.ama
glider.vze.com/. They love Gliders and have
a bunch of accumulated knowledge to share.
Newsletter of the Month: If you are
looking for more of an Indoor FF news fix
than my four-times-a-year column can
offer, subscribe to some of the many fine
newsletters out there. You’ll find loads of
tips and tricks, local flying information,
plans, and other great stuff.
You probably know about Indoor News
and Views (INAV), which is the leading
international Indoor FF-specific
publication. You know, it’s been around
since the beginning of time, it contains a
wealth of Indoor FF knowledge, and it’s
on the must-read list for every serious
competitor. No? Go to the INAV section of
www.indoorduration.com to get the
lowdown.
In addition to the big international
newsletters, there are bunches of local
publications. Since I am fortunate enough
to have several cross my desk each month,
I figured I’d add a review of one every
couple columns or so.
The Brainbusters Newsletter is the
publication of the Brainbusters Free Flight
Club in Virginia. The banner graciously
reads, “Material may be reproduced with
or without credit. Let’s just spread the
word.” Cool attitude!
The club officers list reads like a who’s
who of FF, with longtime USIC CD and
prolific contributor Abram Van Dover
heading things up as president.
Brainbusters meeting minutes feature
positive-sounding topics, including a few
that reach beyond the local scope (e.g.,
sponsoring and running Nats events). It’s
great to see what a positive attitude can
accomplish, even if it’s just the newsletter
editor’s.
The Brainbusters fly Indoor in the fullscale
wind tunnel at Langley Air Force
Base. At roughly 30 feet tall and 60 feet
wide, it’s a little tight (and gets kind of
cold in the wintertime), but these fliers are
getting some nice times in there. How
about more than eight minutes in
MiniStick and Pennyplane, more than 11
minutes in EZB, and more than 50
seconds in Catapult Glider?
Paging through the last few issues of
the newsletter I saw several plans—
including for Artie Jessup’s Catapult
Glider—tips and tricks, contest results,
and lots of Indoor and Outdoor FF
information. If you live in the area or just
want more great stuff to read, contact
Abram Van Dover at (757) 877-2830.
Edition: Model Aviation - 2006/07
Page Numbers: 129,130,131,134
Edition: Model Aviation - 2006/07
Page Numbers: 129,130,131,134
Variable-pitch propellers explained
July 2006 129
Also included in this column:
• New Winning Indoor Designs
book
• What constitutes a good
beginner’s event?
• The Chicago Indoor FF scene
• Newsletter of the month
Free Flight Indoor John Kagan
[[email protected]]
Bernie Hunt’s neat VP uses Kevlar-thread hinges. He was recently awarded the
FAI/CIAM Antonov Diploma for technical innovation in modeling. Aikman photo.
Ray Harlan’s “inverted” VP features pass-through actuator
arms and a boron-reinforced hub.
The author’s VP mechanism is based on the long-standing Cezar
Banks design. The red washer is a ruby used for jeweled
wristwatches.
That’s not a bagel supporting reigning
Indoor FF National Cup champ Tom
Sova’s VP; it’s a Cheerio! Sova photo.
Dezso Orsovai’s VP has wonderful
craftsmanship. The whole mechanism is
only roughly 1/2 inch long. Aikman photo.
VARIABLE-PITCH PROPELLERS: In
the events that allow them, variable-geometry
propellers are a key competitive advantage.
Variable-pitch (VP) propellers are the most
common. There are many different VP styles
and designs, and each aims to improve
performance or increase durability compared
with the others in some way, but the
underlying principle is generally the same.
As commonly used, VP propeller hubs
change the pitch of the propeller blades in
response to the varying torque in the rubber
motor. At high motor torque the hub sets the
blades at a high pitch, reducing the amount of
thrust produced, keeping the model from
climbing into the ceiling. When the torque
decreases, the hub begins “closing,” reducing
the propeller pitch.
Some designs bang from high to low pitch
quickly, and others make the change
throughout a large portion of the flight.
Which is better? There are as many opinions
as there are designs. I prefer the slow-burn
approach. Just make sure the change doesn’t
take so long that you never reach full low
pitch.
At the low-pitch setting the propeller
generates more thrust at a given torque,
extending the flight and hopefully using all
the remaining energy in the motor. With
130 MODEL AVIATION
A Bong Eagles (named for its outdoor flying site: the Bong Recreational Area) mass
launch at Memorial Hall in Racine, Wisconsin. Nice flying site!
Bong Eagles members (L-R) Ivr Kovnat, Otto Curth, Kenny Krempetz, Joe Adamek,
Jack Boone, Jim Gerszewski, Jack Schnobrion, and Kurt Krempetz (kneeling).
fixed-pitch propellers, most people aim to
land with a partial row of knots in the
motor, but a VP will ideally land
completely dead-stick.
Many designs use devices such as
screws or shims to adjust variables such
as spring preload or the high- and lowpitch
stops. These kinds of hubs can be
quickly optimized for different ceiling
heights, specific motors, and even
temperature or humidity changes—a
distinct benefit in competition.
With a VP, instead of backing off
turns to control altitude or changing
motors to fine-tune the flight profile, you
can launch with full torque every time
and use a screwdriver to dial things in.
Look at the accompanying photos for
sampling of current designs. These VP
hubs are approximately .5 inch long and
weigh approximately .1 gram! A
challenge, to be sure, but certainly not
impossible to construct.
For a great VP tutorial, look at Steve
Brown’s article in Indoor News and
Views #89 or the “Articles” section of
Indoor Duration at www.indoorduration.
com. You can find more VP photos at
www.indoornews.com and http://groups.
yahoo.com/group/indoor_construction.
Winning Indoor Designs: You may
know about the 1987-1989 Winning
Indoor Designs book, published by the
National Free Flight Society (NFFS). It is
filled with top-notch Indoor FF plans for
every category, alongside descriptions
and building notes packed with
knowledge.
Most of the designs in the book are
still competitive, but the information is
approaching 20 years old. Furthermore,
the book is no longer in print, making it
that much harder to get your hands on a
copy.
Carl Bakay to the rescue! He has
laboriously assembled a modern collection
of record-setting and US Indoor
Championships (USIC)/Kibbie Domewinning
designs and notes that rivals its
predecessor. I’ve paged through a
preliminary copy and can attest to its
quality.
Whether you are into serious Indoor FF
competition or simply appreciate beauty of
top-level designs, this book is a must-have.
Winning Indoor Designs 2002-2005 is
available for $15 + $4.50 shipping and
handling from Bob Stalick, NFFS
Publications, Box 1775, Albany OR 97321;
E-mail: [email protected].
Making a Good “Beginner Class”: There
are a variety of objectives to choose from
when defining an Indoor FF class, such as
ultimate performance (such as Hand-
Launched Stick), a particular technical
challenge (Ornithopter, Autogiro, etc.), or a
design to fit special sites (such as
MiniStick, originally labeled Living Room
Stick).
One of the most common goals, though,
has been to devise an “easy” event that
would be more accessible to beginners than
the sophisticated classes, with the intent to
attract new participants.
Every so often a familiar-sounding
debate resurfaces regarding one of these
beginner events. Some aspect of the class
has evolved to the point where it is now
hard to be competitive, undermining the
original intent.
EZB has become the ultimate test of
strength vs. weight wood selection, with its
bracing prohibition and lack of a minimum
weight limit. Despite a relatively high
minimum weight, Pennyplane is now an
expert challenge, with biplane
configurations, short coupling, and long
motors on short motorsticks. Bostonian
esigns now commonly employ lifting body
configurations (offending realism purists),
sizes that make the 7-gram target difficult,
and stability-reducing full-body-length
motors.
In response, additional rules that reign in
these areas are proposed, often producing
new classes. F1L—the international version
of US EZB—has a 1.2-gram minimum
weight, making wood selection less critical.
Limited Pennyplane has restrictions on wing
and stabilizer dimensions and is limited to
monoplanes—changes that drastically
improve pitch stability and reduce
complexity.
The most advanced classes have the
fewest rules, and the simplest classes have
the most rules. However, the extra
restrictions are deemed necessary to keep
complexity under control and keep the event
accessible to beginners.
Accessibility is the key point. A certain
construction requirement might not be the
easiest (such as paper covering vs. plastic),
but it should be reasonably obtainable by a
beginner (as opposed to microfilm, for
instance).
Rules that define a successful beginner’s
event have been created several times, but
an area of newcomer acquisition that is
rarely adequately addressed is the definition
of a beginning level of competition
accomplishment. Many beginner events
impose restrictions that hope to keep
newcomers competitive with the experts.
It’s a nice thought, but it has repeatedly
been shown to be unrealistic.
The experts inevitably push the limits of
the design and eek out that small extra
advantage. If success in competition is a
requirement for retaining newcomers (an
assertion that I do not necessarily agree
with), it is unlikely to happen when they are
paired against the veterans.
There has been some discussion in the
Indoor FF community about how to define an
event that separates the newcomers from the
experts, giving beginners a chance to taste
success. Some suggest a handicap system,
similar to that in golf. Others offer tiered
groupings, such as the Sportsman,
Intermediate, Advanced, and Masters classes
in RC Aerobatics. I propose performance
achievement(s)—six minutes with a Limited
Pennyplane, for instance—modeled after RC
Soaring League of Silent Flight levels.
Whatever “recipe for newcomers” people
endorse, we at least all recognize the
importance of sharing our passion. Our
methods may differ, but we love Indoor FF
and want others to experience it too!
If you are interested in discussing Indoor
FF-related topics, consider joining the
various Indoor forums at www.indoor
news.com, http://groups.yahoo.com/
group/indoor_construction, and www.small
flyingarts.com.
Chicago “Local Scene”: Top-level Indoor
Glider competitor Kurt Krempetz sent in the
following report on Indoor FF activity in his
hometown area of Chicago, Illinois:
“There are many clubs that have worked
hard to promote Indoor Free Flight around
Chicago, Illinois. One is the Bong Eagles,
which meets in Milwaukee, Wisconsin.
Typically, the first Thursday evening of
every month they sponsor a Fun-Fly at
Memorial Hall in Racine, Wisconsin. I’ve
included a picture of the group of great guys
who were present in March.
“Twice a year the Bong Eagles holds a
Spring and Fall Indoor Contest for an entire
Sunday. Year after year Jack Boone, Joe
Adams, and Joe Adamek do an excellent job
running the contests. Other notable legends
who are members of the Bong Eagles are
Tony Italiano and Gordy Wisnewski, who
are typically at the Sunday contests helping
others.
“Another club that has worked hard
promoting Indoor Free Flight is the Chicago
Aeronuts. For many years Bob Warmann
has been the Contest Director of the Annual
Midwest Championships.
“Bob has done an excellent job
organizing and running the contest along
with being a fierce competitor. For the last
few years the Chicago Aeronuts has held
this event in the Armory at the University of
Illinois—a good Category III site. Notable
legends who are members of the Chicago
Aeronuts are Chuck Markos and Ed
Konefes.
“If you are interested in Indoor Freefamily’s Glider Web site at www.ama
glider.vze.com/. They love Gliders and have
a bunch of accumulated knowledge to share.
Newsletter of the Month: If you are
looking for more of an Indoor FF news fix
than my four-times-a-year column can
offer, subscribe to some of the many fine
newsletters out there. You’ll find loads of
tips and tricks, local flying information,
plans, and other great stuff.
You probably know about Indoor News
and Views (INAV), which is the leading
international Indoor FF-specific
publication. You know, it’s been around
since the beginning of time, it contains a
wealth of Indoor FF knowledge, and it’s
on the must-read list for every serious
competitor. No? Go to the INAV section of
www.indoorduration.com to get the
lowdown.
In addition to the big international
newsletters, there are bunches of local
publications. Since I am fortunate enough
to have several cross my desk each month,
I figured I’d add a review of one every
couple columns or so.
The Brainbusters Newsletter is the
publication of the Brainbusters Free Flight
Club in Virginia. The banner graciously
reads, “Material may be reproduced with
or without credit. Let’s just spread the
word.” Cool attitude!
The club officers list reads like a who’s
who of FF, with longtime USIC CD and
prolific contributor Abram Van Dover
heading things up as president.
Brainbusters meeting minutes feature
positive-sounding topics, including a few
that reach beyond the local scope (e.g.,
sponsoring and running Nats events). It’s
great to see what a positive attitude can
accomplish, even if it’s just the newsletter
editor’s.
The Brainbusters fly Indoor in the fullscale
wind tunnel at Langley Air Force
Base. At roughly 30 feet tall and 60 feet
wide, it’s a little tight (and gets kind of
cold in the wintertime), but these fliers are
getting some nice times in there. How
about more than eight minutes in
MiniStick and Pennyplane, more than 11
minutes in EZB, and more than 50
seconds in Catapult Glider?
Paging through the last few issues of
the newsletter I saw several plans—
including for Artie Jessup’s Catapult
Glider—tips and tricks, contest results,
and lots of Indoor and Outdoor FF
information. If you live in the area or just
want more great stuff to read, contact
Abram Van Dover at (757) 877-2830.
Edition: Model Aviation - 2006/07
Page Numbers: 129,130,131,134
Variable-pitch propellers explained
July 2006 129
Also included in this column:
• New Winning Indoor Designs
book
• What constitutes a good
beginner’s event?
• The Chicago Indoor FF scene
• Newsletter of the month
Free Flight Indoor John Kagan
[[email protected]]
Bernie Hunt’s neat VP uses Kevlar-thread hinges. He was recently awarded the
FAI/CIAM Antonov Diploma for technical innovation in modeling. Aikman photo.
Ray Harlan’s “inverted” VP features pass-through actuator
arms and a boron-reinforced hub.
The author’s VP mechanism is based on the long-standing Cezar
Banks design. The red washer is a ruby used for jeweled
wristwatches.
That’s not a bagel supporting reigning
Indoor FF National Cup champ Tom
Sova’s VP; it’s a Cheerio! Sova photo.
Dezso Orsovai’s VP has wonderful
craftsmanship. The whole mechanism is
only roughly 1/2 inch long. Aikman photo.
VARIABLE-PITCH PROPELLERS: In
the events that allow them, variable-geometry
propellers are a key competitive advantage.
Variable-pitch (VP) propellers are the most
common. There are many different VP styles
and designs, and each aims to improve
performance or increase durability compared
with the others in some way, but the
underlying principle is generally the same.
As commonly used, VP propeller hubs
change the pitch of the propeller blades in
response to the varying torque in the rubber
motor. At high motor torque the hub sets the
blades at a high pitch, reducing the amount of
thrust produced, keeping the model from
climbing into the ceiling. When the torque
decreases, the hub begins “closing,” reducing
the propeller pitch.
Some designs bang from high to low pitch
quickly, and others make the change
throughout a large portion of the flight.
Which is better? There are as many opinions
as there are designs. I prefer the slow-burn
approach. Just make sure the change doesn’t
take so long that you never reach full low
pitch.
At the low-pitch setting the propeller
generates more thrust at a given torque,
extending the flight and hopefully using all
the remaining energy in the motor. With
130 MODEL AVIATION
A Bong Eagles (named for its outdoor flying site: the Bong Recreational Area) mass
launch at Memorial Hall in Racine, Wisconsin. Nice flying site!
Bong Eagles members (L-R) Ivr Kovnat, Otto Curth, Kenny Krempetz, Joe Adamek,
Jack Boone, Jim Gerszewski, Jack Schnobrion, and Kurt Krempetz (kneeling).
fixed-pitch propellers, most people aim to
land with a partial row of knots in the
motor, but a VP will ideally land
completely dead-stick.
Many designs use devices such as
screws or shims to adjust variables such
as spring preload or the high- and lowpitch
stops. These kinds of hubs can be
quickly optimized for different ceiling
heights, specific motors, and even
temperature or humidity changes—a
distinct benefit in competition.
With a VP, instead of backing off
turns to control altitude or changing
motors to fine-tune the flight profile, you
can launch with full torque every time
and use a screwdriver to dial things in.
Look at the accompanying photos for
sampling of current designs. These VP
hubs are approximately .5 inch long and
weigh approximately .1 gram! A
challenge, to be sure, but certainly not
impossible to construct.
For a great VP tutorial, look at Steve
Brown’s article in Indoor News and
Views #89 or the “Articles” section of
Indoor Duration at www.indoorduration.
com. You can find more VP photos at
www.indoornews.com and http://groups.
yahoo.com/group/indoor_construction.
Winning Indoor Designs: You may
know about the 1987-1989 Winning
Indoor Designs book, published by the
National Free Flight Society (NFFS). It is
filled with top-notch Indoor FF plans for
every category, alongside descriptions
and building notes packed with
knowledge.
Most of the designs in the book are
still competitive, but the information is
approaching 20 years old. Furthermore,
the book is no longer in print, making it
that much harder to get your hands on a
copy.
Carl Bakay to the rescue! He has
laboriously assembled a modern collection
of record-setting and US Indoor
Championships (USIC)/Kibbie Domewinning
designs and notes that rivals its
predecessor. I’ve paged through a
preliminary copy and can attest to its
quality.
Whether you are into serious Indoor FF
competition or simply appreciate beauty of
top-level designs, this book is a must-have.
Winning Indoor Designs 2002-2005 is
available for $15 + $4.50 shipping and
handling from Bob Stalick, NFFS
Publications, Box 1775, Albany OR 97321;
E-mail: [email protected].
Making a Good “Beginner Class”: There
are a variety of objectives to choose from
when defining an Indoor FF class, such as
ultimate performance (such as Hand-
Launched Stick), a particular technical
challenge (Ornithopter, Autogiro, etc.), or a
design to fit special sites (such as
MiniStick, originally labeled Living Room
Stick).
One of the most common goals, though,
has been to devise an “easy” event that
would be more accessible to beginners than
the sophisticated classes, with the intent to
attract new participants.
Every so often a familiar-sounding
debate resurfaces regarding one of these
beginner events. Some aspect of the class
has evolved to the point where it is now
hard to be competitive, undermining the
original intent.
EZB has become the ultimate test of
strength vs. weight wood selection, with its
bracing prohibition and lack of a minimum
weight limit. Despite a relatively high
minimum weight, Pennyplane is now an
expert challenge, with biplane
configurations, short coupling, and long
motors on short motorsticks. Bostonian
esigns now commonly employ lifting body
configurations (offending realism purists),
sizes that make the 7-gram target difficult,
and stability-reducing full-body-length
motors.
In response, additional rules that reign in
these areas are proposed, often producing
new classes. F1L—the international version
of US EZB—has a 1.2-gram minimum
weight, making wood selection less critical.
Limited Pennyplane has restrictions on wing
and stabilizer dimensions and is limited to
monoplanes—changes that drastically
improve pitch stability and reduce
complexity.
The most advanced classes have the
fewest rules, and the simplest classes have
the most rules. However, the extra
restrictions are deemed necessary to keep
complexity under control and keep the event
accessible to beginners.
Accessibility is the key point. A certain
construction requirement might not be the
easiest (such as paper covering vs. plastic),
but it should be reasonably obtainable by a
beginner (as opposed to microfilm, for
instance).
Rules that define a successful beginner’s
event have been created several times, but
an area of newcomer acquisition that is
rarely adequately addressed is the definition
of a beginning level of competition
accomplishment. Many beginner events
impose restrictions that hope to keep
newcomers competitive with the experts.
It’s a nice thought, but it has repeatedly
been shown to be unrealistic.
The experts inevitably push the limits of
the design and eek out that small extra
advantage. If success in competition is a
requirement for retaining newcomers (an
assertion that I do not necessarily agree
with), it is unlikely to happen when they are
paired against the veterans.
There has been some discussion in the
Indoor FF community about how to define an
event that separates the newcomers from the
experts, giving beginners a chance to taste
success. Some suggest a handicap system,
similar to that in golf. Others offer tiered
groupings, such as the Sportsman,
Intermediate, Advanced, and Masters classes
in RC Aerobatics. I propose performance
achievement(s)—six minutes with a Limited
Pennyplane, for instance—modeled after RC
Soaring League of Silent Flight levels.
Whatever “recipe for newcomers” people
endorse, we at least all recognize the
importance of sharing our passion. Our
methods may differ, but we love Indoor FF
and want others to experience it too!
If you are interested in discussing Indoor
FF-related topics, consider joining the
various Indoor forums at www.indoor
news.com, http://groups.yahoo.com/
group/indoor_construction, and www.small
flyingarts.com.
Chicago “Local Scene”: Top-level Indoor
Glider competitor Kurt Krempetz sent in the
following report on Indoor FF activity in his
hometown area of Chicago, Illinois:
“There are many clubs that have worked
hard to promote Indoor Free Flight around
Chicago, Illinois. One is the Bong Eagles,
which meets in Milwaukee, Wisconsin.
Typically, the first Thursday evening of
every month they sponsor a Fun-Fly at
Memorial Hall in Racine, Wisconsin. I’ve
included a picture of the group of great guys
who were present in March.
“Twice a year the Bong Eagles holds a
Spring and Fall Indoor Contest for an entire
Sunday. Year after year Jack Boone, Joe
Adams, and Joe Adamek do an excellent job
running the contests. Other notable legends
who are members of the Bong Eagles are
Tony Italiano and Gordy Wisnewski, who
are typically at the Sunday contests helping
others.
“Another club that has worked hard
promoting Indoor Free Flight is the Chicago
Aeronuts. For many years Bob Warmann
has been the Contest Director of the Annual
Midwest Championships.
“Bob has done an excellent job
organizing and running the contest along
with being a fierce competitor. For the last
few years the Chicago Aeronuts has held
this event in the Armory at the University of
Illinois—a good Category III site. Notable
legends who are members of the Chicago
Aeronuts are Chuck Markos and Ed
Konefes.
“If you are interested in Indoor Freefamily’s Glider Web site at www.ama
glider.vze.com/. They love Gliders and have
a bunch of accumulated knowledge to share.
Newsletter of the Month: If you are
looking for more of an Indoor FF news fix
than my four-times-a-year column can
offer, subscribe to some of the many fine
newsletters out there. You’ll find loads of
tips and tricks, local flying information,
plans, and other great stuff.
You probably know about Indoor News
and Views (INAV), which is the leading
international Indoor FF-specific
publication. You know, it’s been around
since the beginning of time, it contains a
wealth of Indoor FF knowledge, and it’s
on the must-read list for every serious
competitor. No? Go to the INAV section of
www.indoorduration.com to get the
lowdown.
In addition to the big international
newsletters, there are bunches of local
publications. Since I am fortunate enough
to have several cross my desk each month,
I figured I’d add a review of one every
couple columns or so.
The Brainbusters Newsletter is the
publication of the Brainbusters Free Flight
Club in Virginia. The banner graciously
reads, “Material may be reproduced with
or without credit. Let’s just spread the
word.” Cool attitude!
The club officers list reads like a who’s
who of FF, with longtime USIC CD and
prolific contributor Abram Van Dover
heading things up as president.
Brainbusters meeting minutes feature
positive-sounding topics, including a few
that reach beyond the local scope (e.g.,
sponsoring and running Nats events). It’s
great to see what a positive attitude can
accomplish, even if it’s just the newsletter
editor’s.
The Brainbusters fly Indoor in the fullscale
wind tunnel at Langley Air Force
Base. At roughly 30 feet tall and 60 feet
wide, it’s a little tight (and gets kind of
cold in the wintertime), but these fliers are
getting some nice times in there. How
about more than eight minutes in
MiniStick and Pennyplane, more than 11
minutes in EZB, and more than 50
seconds in Catapult Glider?
Paging through the last few issues of
the newsletter I saw several plans—
including for Artie Jessup’s Catapult
Glider—tips and tricks, contest results,
and lots of Indoor and Outdoor FF
information. If you live in the area or just
want more great stuff to read, contact
Abram Van Dover at (757) 877-2830.
Edition: Model Aviation - 2006/07
Page Numbers: 129,130,131,134
Variable-pitch propellers explained
July 2006 129
Also included in this column:
• New Winning Indoor Designs
book
• What constitutes a good
beginner’s event?
• The Chicago Indoor FF scene
• Newsletter of the month
Free Flight Indoor John Kagan
[[email protected]]
Bernie Hunt’s neat VP uses Kevlar-thread hinges. He was recently awarded the
FAI/CIAM Antonov Diploma for technical innovation in modeling. Aikman photo.
Ray Harlan’s “inverted” VP features pass-through actuator
arms and a boron-reinforced hub.
The author’s VP mechanism is based on the long-standing Cezar
Banks design. The red washer is a ruby used for jeweled
wristwatches.
That’s not a bagel supporting reigning
Indoor FF National Cup champ Tom
Sova’s VP; it’s a Cheerio! Sova photo.
Dezso Orsovai’s VP has wonderful
craftsmanship. The whole mechanism is
only roughly 1/2 inch long. Aikman photo.
VARIABLE-PITCH PROPELLERS: In
the events that allow them, variable-geometry
propellers are a key competitive advantage.
Variable-pitch (VP) propellers are the most
common. There are many different VP styles
and designs, and each aims to improve
performance or increase durability compared
with the others in some way, but the
underlying principle is generally the same.
As commonly used, VP propeller hubs
change the pitch of the propeller blades in
response to the varying torque in the rubber
motor. At high motor torque the hub sets the
blades at a high pitch, reducing the amount of
thrust produced, keeping the model from
climbing into the ceiling. When the torque
decreases, the hub begins “closing,” reducing
the propeller pitch.
Some designs bang from high to low pitch
quickly, and others make the change
throughout a large portion of the flight.
Which is better? There are as many opinions
as there are designs. I prefer the slow-burn
approach. Just make sure the change doesn’t
take so long that you never reach full low
pitch.
At the low-pitch setting the propeller
generates more thrust at a given torque,
extending the flight and hopefully using all
the remaining energy in the motor. With
130 MODEL AVIATION
A Bong Eagles (named for its outdoor flying site: the Bong Recreational Area) mass
launch at Memorial Hall in Racine, Wisconsin. Nice flying site!
Bong Eagles members (L-R) Ivr Kovnat, Otto Curth, Kenny Krempetz, Joe Adamek,
Jack Boone, Jim Gerszewski, Jack Schnobrion, and Kurt Krempetz (kneeling).
fixed-pitch propellers, most people aim to
land with a partial row of knots in the
motor, but a VP will ideally land
completely dead-stick.
Many designs use devices such as
screws or shims to adjust variables such
as spring preload or the high- and lowpitch
stops. These kinds of hubs can be
quickly optimized for different ceiling
heights, specific motors, and even
temperature or humidity changes—a
distinct benefit in competition.
With a VP, instead of backing off
turns to control altitude or changing
motors to fine-tune the flight profile, you
can launch with full torque every time
and use a screwdriver to dial things in.
Look at the accompanying photos for
sampling of current designs. These VP
hubs are approximately .5 inch long and
weigh approximately .1 gram! A
challenge, to be sure, but certainly not
impossible to construct.
For a great VP tutorial, look at Steve
Brown’s article in Indoor News and
Views #89 or the “Articles” section of
Indoor Duration at www.indoorduration.
com. You can find more VP photos at
www.indoornews.com and http://groups.
yahoo.com/group/indoor_construction.
Winning Indoor Designs: You may
know about the 1987-1989 Winning
Indoor Designs book, published by the
National Free Flight Society (NFFS). It is
filled with top-notch Indoor FF plans for
every category, alongside descriptions
and building notes packed with
knowledge.
Most of the designs in the book are
still competitive, but the information is
approaching 20 years old. Furthermore,
the book is no longer in print, making it
that much harder to get your hands on a
copy.
Carl Bakay to the rescue! He has
laboriously assembled a modern collection
of record-setting and US Indoor
Championships (USIC)/Kibbie Domewinning
designs and notes that rivals its
predecessor. I’ve paged through a
preliminary copy and can attest to its
quality.
Whether you are into serious Indoor FF
competition or simply appreciate beauty of
top-level designs, this book is a must-have.
Winning Indoor Designs 2002-2005 is
available for $15 + $4.50 shipping and
handling from Bob Stalick, NFFS
Publications, Box 1775, Albany OR 97321;
E-mail: [email protected].
Making a Good “Beginner Class”: There
are a variety of objectives to choose from
when defining an Indoor FF class, such as
ultimate performance (such as Hand-
Launched Stick), a particular technical
challenge (Ornithopter, Autogiro, etc.), or a
design to fit special sites (such as
MiniStick, originally labeled Living Room
Stick).
One of the most common goals, though,
has been to devise an “easy” event that
would be more accessible to beginners than
the sophisticated classes, with the intent to
attract new participants.
Every so often a familiar-sounding
debate resurfaces regarding one of these
beginner events. Some aspect of the class
has evolved to the point where it is now
hard to be competitive, undermining the
original intent.
EZB has become the ultimate test of
strength vs. weight wood selection, with its
bracing prohibition and lack of a minimum
weight limit. Despite a relatively high
minimum weight, Pennyplane is now an
expert challenge, with biplane
configurations, short coupling, and long
motors on short motorsticks. Bostonian
esigns now commonly employ lifting body
configurations (offending realism purists),
sizes that make the 7-gram target difficult,
and stability-reducing full-body-length
motors.
In response, additional rules that reign in
these areas are proposed, often producing
new classes. F1L—the international version
of US EZB—has a 1.2-gram minimum
weight, making wood selection less critical.
Limited Pennyplane has restrictions on wing
and stabilizer dimensions and is limited to
monoplanes—changes that drastically
improve pitch stability and reduce
complexity.
The most advanced classes have the
fewest rules, and the simplest classes have
the most rules. However, the extra
restrictions are deemed necessary to keep
complexity under control and keep the event
accessible to beginners.
Accessibility is the key point. A certain
construction requirement might not be the
easiest (such as paper covering vs. plastic),
but it should be reasonably obtainable by a
beginner (as opposed to microfilm, for
instance).
Rules that define a successful beginner’s
event have been created several times, but
an area of newcomer acquisition that is
rarely adequately addressed is the definition
of a beginning level of competition
accomplishment. Many beginner events
impose restrictions that hope to keep
newcomers competitive with the experts.
It’s a nice thought, but it has repeatedly
been shown to be unrealistic.
The experts inevitably push the limits of
the design and eek out that small extra
advantage. If success in competition is a
requirement for retaining newcomers (an
assertion that I do not necessarily agree
with), it is unlikely to happen when they are
paired against the veterans.
There has been some discussion in the
Indoor FF community about how to define an
event that separates the newcomers from the
experts, giving beginners a chance to taste
success. Some suggest a handicap system,
similar to that in golf. Others offer tiered
groupings, such as the Sportsman,
Intermediate, Advanced, and Masters classes
in RC Aerobatics. I propose performance
achievement(s)—six minutes with a Limited
Pennyplane, for instance—modeled after RC
Soaring League of Silent Flight levels.
Whatever “recipe for newcomers” people
endorse, we at least all recognize the
importance of sharing our passion. Our
methods may differ, but we love Indoor FF
and want others to experience it too!
If you are interested in discussing Indoor
FF-related topics, consider joining the
various Indoor forums at www.indoor
news.com, http://groups.yahoo.com/
group/indoor_construction, and www.small
flyingarts.com.
Chicago “Local Scene”: Top-level Indoor
Glider competitor Kurt Krempetz sent in the
following report on Indoor FF activity in his
hometown area of Chicago, Illinois:
“There are many clubs that have worked
hard to promote Indoor Free Flight around
Chicago, Illinois. One is the Bong Eagles,
which meets in Milwaukee, Wisconsin.
Typically, the first Thursday evening of
every month they sponsor a Fun-Fly at
Memorial Hall in Racine, Wisconsin. I’ve
included a picture of the group of great guys
who were present in March.
“Twice a year the Bong Eagles holds a
Spring and Fall Indoor Contest for an entire
Sunday. Year after year Jack Boone, Joe
Adams, and Joe Adamek do an excellent job
running the contests. Other notable legends
who are members of the Bong Eagles are
Tony Italiano and Gordy Wisnewski, who
are typically at the Sunday contests helping
others.
“Another club that has worked hard
promoting Indoor Free Flight is the Chicago
Aeronuts. For many years Bob Warmann
has been the Contest Director of the Annual
Midwest Championships.
“Bob has done an excellent job
organizing and running the contest along
with being a fierce competitor. For the last
few years the Chicago Aeronuts has held
this event in the Armory at the University of
Illinois—a good Category III site. Notable
legends who are members of the Chicago
Aeronuts are Chuck Markos and Ed
Konefes.
“If you are interested in Indoor Freefamily’s Glider Web site at www.ama
glider.vze.com/. They love Gliders and have
a bunch of accumulated knowledge to share.
Newsletter of the Month: If you are
looking for more of an Indoor FF news fix
than my four-times-a-year column can
offer, subscribe to some of the many fine
newsletters out there. You’ll find loads of
tips and tricks, local flying information,
plans, and other great stuff.
You probably know about Indoor News
and Views (INAV), which is the leading
international Indoor FF-specific
publication. You know, it’s been around
since the beginning of time, it contains a
wealth of Indoor FF knowledge, and it’s
on the must-read list for every serious
competitor. No? Go to the INAV section of
www.indoorduration.com to get the
lowdown.
In addition to the big international
newsletters, there are bunches of local
publications. Since I am fortunate enough
to have several cross my desk each month,
I figured I’d add a review of one every
couple columns or so.
The Brainbusters Newsletter is the
publication of the Brainbusters Free Flight
Club in Virginia. The banner graciously
reads, “Material may be reproduced with
or without credit. Let’s just spread the
word.” Cool attitude!
The club officers list reads like a who’s
who of FF, with longtime USIC CD and
prolific contributor Abram Van Dover
heading things up as president.
Brainbusters meeting minutes feature
positive-sounding topics, including a few
that reach beyond the local scope (e.g.,
sponsoring and running Nats events). It’s
great to see what a positive attitude can
accomplish, even if it’s just the newsletter
editor’s.
The Brainbusters fly Indoor in the fullscale
wind tunnel at Langley Air Force
Base. At roughly 30 feet tall and 60 feet
wide, it’s a little tight (and gets kind of
cold in the wintertime), but these fliers are
getting some nice times in there. How
about more than eight minutes in
MiniStick and Pennyplane, more than 11
minutes in EZB, and more than 50
seconds in Catapult Glider?
Paging through the last few issues of
the newsletter I saw several plans—
including for Artie Jessup’s Catapult
Glider—tips and tricks, contest results,
and lots of Indoor and Outdoor FF
information. If you live in the area or just
want more great stuff to read, contact
Abram Van Dover at (757) 877-2830.