122 MODEL AVIATION
New ideas from the Nats
[[email protected]]
Free Flight Duration Louis Joyner
IDEAS: One of the many reasons for
going to the Nats, or any big contest, is to
get ideas. For those of us without a local
club, contests often offer the only way to
examine models firsthand and to discuss
design and construction ideas.
A firsthand look is especially helpful if
you are thinking about trying a new event.
Most modelers are willing to share what
they do and how they do it—just not
during the heat of competition. Pick the
lulls in activity to ask the detailed
questions and take a close look at models
and field equipment. Take notes and use a
camera to record details.
Here are a few ideas I picked up at last
year’s Nats.
A P-30 with Punch: Ross Jahnke had a
nice-looking P-30 that used a timeroperated
auto stabilizer to help control the
power burst. While auto stabilizers are
almost universally used in F1B Wakefield,
and fairly common for F1G Coupes, they
are not often seen in the AMA Rubber
events such as P-30, Mulvihill, and
Moffett.
An auto stabilizer holds the stabilizer’s
TE down slightly at launch, decreasing the
decalage (difference between the wing and
stabilizer incidence). This helps reduce the
looping tendency during the high-speed
phase of the motor run. After a few
seconds the stabilizer’s TE comes up to the
glide position for the cruise portion of the
climb and for the glide.
The main benefit of using an auto
stabilizer is the much straighter and more
vertical climb during the burst. For a
model with a relatively short motor run,
such as an F1B or F1G, a significant
percentage of the rubber motor’s total
energy is released in the first few seconds.
It is important that this energy is used to
get the model as high as possible. That
means a hard launch, and a never-vertical
climb for the first 3 to 4 seconds,
transitioning into a spiral climb.
A typical Wakefield might gain a third
of the total altitude in the first 4 seconds
and be at half of its final altitude at 12
seconds; the rest of the height gain takes
longer, perhaps another 30 seconds or
more.
For models with longer motor runs,
such as Mulvihill, Moffett, and most
Nostalgia and Old-Timer models, the burst
is still there, but it is a lower percentage of
the total stored energy. For these models, a
spiral climb and a longer motor run allow
good altitude gain without the need for
auto surfaces. Often P-30s have motor runs
of 90 seconds or more.
Ross’ P-30 uses a shorter, thicker
motor: six strands of 1/8-inch rubber. This
gives a maximum torque of 15 inch-ounces
at approximately 1,100 turns and a motor
run of approximately 30 to 40 seconds.
“I have tried to reduce frontal area to
climb fast,” he said. “It is a rocket and I
can throw it as hard as I would throw an
F1B. The general comment I get from
bystanders is how fast my P-30s climb.”
On his P-30, Ross uses the auto
stabilizer to control the fast initial climb
and prevent looping. A viscous timer
mounted in the pylon controls both the
auto stabilizer and DT. “The auto stab
kicks in at around 5 to 7 seconds; there is
very little deflection but it smoothes out
the first part of the climb,” said Ross.
There are advantages and disadvantages
to a short motor run and fast climb. The
most important advantage is the ability to
Paul Crowley’s rubber-powered
Mulvihill is a result of his halfcentury
of F1B Wakefield
experience. It uses a short rolled
balsa motor tube and a lightweight
carbon-aluminum tailboom
salvaged from an old F1B.
A viscous timer mounted in the pylon triggers
the auto stabilizer and the pop-up wing DT.
The wing is covered with Polyspan on the top
and bottom back to the spar for extra strength.
Instead of the usual balsa TE, Crowley’s
model uses a 1/8-inch-thick balsa strip
with thin carbon fiber attached to front,
top, and bottom. The result is
lightweight and stiff.
02sig4.QXD_00MSTRPG.QXD 12/16/11 4:45 PM Page 122get the model up through ground
turbulence, which can play havoc with the
power pattern of a slower-climbing model.
This is especially important on windy days
when the flightline is often located
downwind of a tree line. For a P-30 with
the required freewheeling propeller, using
a long motor run means more time under
power and less time gliding with the extra
drag of a freewheeling propeller.
Ross’ P-30 design dates back two
decades. “The name of the design is Quick
One and this is number 10 in the series. It
has evolved since the first one was built on
1981,” he said. “Quick Ones numbers 4
and 5 were published in the July 1989 MA.
If you look back at the article you will see
that the things I have kept are the forward
DT system and the flat center section of
the wing. There has been a steady
evolution. If you saw each model, the
continuity would be evident.”
Wakefield Inspired: Paul Crowley’s
Mulvihill model also makes use of an auto
surface. “I use an auto rudder only and fly
right-right. On that model it’s off the
timer,” he says. “Since you never really fly
at max power, I don’t see the need for an
auto stab. Most of the time I can get three
flights out of a motor with no break-in.”
(Typically, F1B motors are wound to the
maximum limit and used only once;
broken strands after one winding areconsidered normal.)
“I fly the same torque by just adding
turns. This way I use 60-gram motors on
a 275-square-inch Mulvihill. It was an
easy way to take weight out of the model
by using a shorter motor tube.”
To connect that shorter, rolled-balsa
motor tube to the tail, Paul uses a carbonaluminum
tailboom. These are commonly
used for F1B models, which Paul also
flies. Typically, the booms are roughly
30-inches long and taper from
approximately ½ inch in diameter to
roughly 3/16 inch. The weight is roughly
7 grams.
Although the carbon-aluminum booms
are much lighter and stiffer than a rolledbalsa
boom, they are fragile and
occasionally break immediately in front
of the stabilizer or near the front
attachment point. Most who have flown
F1B for any time have a collection of
boom pieces that are approximately 18 to
24 inches. “Yes, I salvaged the tailboom
and coupling from an old Wake,” said
Paul.
Another interesting idea on Paul’s
model was the wing TE. A typical TE for
a model this size would be a piece of 1/8 x
½ balsa TE stock. A modern F1B aircraft
would use a thin carbon-fiber rectangle,
roughly .5 x 2.8mm (approximately .02 x
.11 inches) in size, tied to the carbonfiber
D-box with balsa ribs capped top
and bottom with thin (.003 inch) carbonfiber
strips.
Paul used both balsa and carbon on his
TE. “The trailing edge is 0.125 x 0.20-
inch balsa capped with 0.003-inch carbon
on the front, top, and bottom. It tapers to
0.125 x 0.125 inches at the tip. The balsa
is around 6 pounds per cubic foot,” said
Paul.
The result is a TE that is stiffer than
either solid balsa or thin carbon strip.
“With the wide rib spacing I use, you
need a stiffer trailing edge,” he said. “If
you use the small cross-section F1B
trailing edge, you must use carbon-fiber
cap strips to hold them to the ribs, which
adds weight.”
E-30 Short Kit: Don DeLoach has
added another model to his stable of
short kits. This one is the Super Pearl
202E. “It’s not a Mini Pearl,” said Don.
“It’s an all-new design with different
moments, airfoils, and, most
importantly, a much stiffer construction,
designed for plastic coverings and high
speed.”
Intended for the National Free Flight
Society (NFFS) E-36 event, it spans 34¾
inches with a wing area of 202 square
inches. The prototype, covered with ¾
mil Mylar, weighed in at 135 grams
ready to fly.
What is a short kit? A traditional kit
includes all of the wood needed, the
plans, some other hardware, and usually
the covering. The modeler supplies the
glue, dope, engine, etc. A short kit
typically includes ribs and some other
parts. You supply the long stuff: balsa
strip for wing and stabilizer LEs, TEs,
spars, and fuselage sheet wood.
Covering material, engine, and other
hardware must be provided by the
builder. Sometimes the plans are
included in a short kit and sometimes
they’re sold separately.
The Super Pearl 202E short kit
includes 115 laser-cut balsa parts such as
wing and stabilizer ribs and pylon
formers. Also included are some lasercut
plywood pieces. You will need to
supply strip balsa for wing and stabilizer
construction, sheet balsa for the fin and
pylon sides, and the carbon boom for the
fuselage.
The plans are sold separately,
allowing you to order two or more short
kits of ribs and only have to pay for one
set of plans. The short kit is $18 and the
plans are $6. Shipping is an additional
$6.
The fuselage is a 32-inch taperedcarbon-fiber boom similar to those used
for discus-launch gliders. Don suggested
sources for the boom as well as motor,
propeller, and other electronics. Total
cost to get a model in the air should be
approximately $100, not counting
shipping. You’ll also need a battery
charger/balancer ($30).
The recommended motor is the AX-
1806N 2500 Kv outrunner from Hobby
King. The recommended propeller setup
is a pair of 7.5 x 4 Graupner blades in a
folding hub, all from Texas Timers. The
battery is a Thunder Power 325 mAh, 2S
(7.4 volt) 65C from RC LiPos.
You can find the rules for the E-36
event at the NFFS website. NFFS also
offers plans for two other E-36 designs:
John Oldenkamp’s JouleBox E-36,
which won the 2011 Nats, and Hal
Cover’s Short Circuit, winner of the
2011 Issacson meet at Lost Hills,
California.
2011 Nats DVD: Alan Abriss spent a
week at the Nats filming the action. The
result is a 115-minute video that shows a
wide variety of outdoor FF activities,
including Electric, Dawn Unlimited, and
ROW. Also included is footage of some
of the Flying Aces Scale events and a
video shot from a model in flight.
The 2011 Free Flight National
Championships DVD is $20 plus $4
shipping and handling. You can order it
from the Homegrown Productions
website using a credit card or by mail
from Alan Abriss, 94-20 66th Ave., Suite
1G, Rego Park NY 11374. Make checkspayable to Alan Abriss. MA
Edition: Model Aviation - 2012/02
Page Numbers: 122,123,124,125
Edition: Model Aviation - 2012/02
Page Numbers: 122,123,124,125
122 MODEL AVIATION
New ideas from the Nats
[[email protected]]
Free Flight Duration Louis Joyner
IDEAS: One of the many reasons for
going to the Nats, or any big contest, is to
get ideas. For those of us without a local
club, contests often offer the only way to
examine models firsthand and to discuss
design and construction ideas.
A firsthand look is especially helpful if
you are thinking about trying a new event.
Most modelers are willing to share what
they do and how they do it—just not
during the heat of competition. Pick the
lulls in activity to ask the detailed
questions and take a close look at models
and field equipment. Take notes and use a
camera to record details.
Here are a few ideas I picked up at last
year’s Nats.
A P-30 with Punch: Ross Jahnke had a
nice-looking P-30 that used a timeroperated
auto stabilizer to help control the
power burst. While auto stabilizers are
almost universally used in F1B Wakefield,
and fairly common for F1G Coupes, they
are not often seen in the AMA Rubber
events such as P-30, Mulvihill, and
Moffett.
An auto stabilizer holds the stabilizer’s
TE down slightly at launch, decreasing the
decalage (difference between the wing and
stabilizer incidence). This helps reduce the
looping tendency during the high-speed
phase of the motor run. After a few
seconds the stabilizer’s TE comes up to the
glide position for the cruise portion of the
climb and for the glide.
The main benefit of using an auto
stabilizer is the much straighter and more
vertical climb during the burst. For a
model with a relatively short motor run,
such as an F1B or F1G, a significant
percentage of the rubber motor’s total
energy is released in the first few seconds.
It is important that this energy is used to
get the model as high as possible. That
means a hard launch, and a never-vertical
climb for the first 3 to 4 seconds,
transitioning into a spiral climb.
A typical Wakefield might gain a third
of the total altitude in the first 4 seconds
and be at half of its final altitude at 12
seconds; the rest of the height gain takes
longer, perhaps another 30 seconds or
more.
For models with longer motor runs,
such as Mulvihill, Moffett, and most
Nostalgia and Old-Timer models, the burst
is still there, but it is a lower percentage of
the total stored energy. For these models, a
spiral climb and a longer motor run allow
good altitude gain without the need for
auto surfaces. Often P-30s have motor runs
of 90 seconds or more.
Ross’ P-30 uses a shorter, thicker
motor: six strands of 1/8-inch rubber. This
gives a maximum torque of 15 inch-ounces
at approximately 1,100 turns and a motor
run of approximately 30 to 40 seconds.
“I have tried to reduce frontal area to
climb fast,” he said. “It is a rocket and I
can throw it as hard as I would throw an
F1B. The general comment I get from
bystanders is how fast my P-30s climb.”
On his P-30, Ross uses the auto
stabilizer to control the fast initial climb
and prevent looping. A viscous timer
mounted in the pylon controls both the
auto stabilizer and DT. “The auto stab
kicks in at around 5 to 7 seconds; there is
very little deflection but it smoothes out
the first part of the climb,” said Ross.
There are advantages and disadvantages
to a short motor run and fast climb. The
most important advantage is the ability to
Paul Crowley’s rubber-powered
Mulvihill is a result of his halfcentury
of F1B Wakefield
experience. It uses a short rolled
balsa motor tube and a lightweight
carbon-aluminum tailboom
salvaged from an old F1B.
A viscous timer mounted in the pylon triggers
the auto stabilizer and the pop-up wing DT.
The wing is covered with Polyspan on the top
and bottom back to the spar for extra strength.
Instead of the usual balsa TE, Crowley’s
model uses a 1/8-inch-thick balsa strip
with thin carbon fiber attached to front,
top, and bottom. The result is
lightweight and stiff.
02sig4.QXD_00MSTRPG.QXD 12/16/11 4:45 PM Page 122get the model up through ground
turbulence, which can play havoc with the
power pattern of a slower-climbing model.
This is especially important on windy days
when the flightline is often located
downwind of a tree line. For a P-30 with
the required freewheeling propeller, using
a long motor run means more time under
power and less time gliding with the extra
drag of a freewheeling propeller.
Ross’ P-30 design dates back two
decades. “The name of the design is Quick
One and this is number 10 in the series. It
has evolved since the first one was built on
1981,” he said. “Quick Ones numbers 4
and 5 were published in the July 1989 MA.
If you look back at the article you will see
that the things I have kept are the forward
DT system and the flat center section of
the wing. There has been a steady
evolution. If you saw each model, the
continuity would be evident.”
Wakefield Inspired: Paul Crowley’s
Mulvihill model also makes use of an auto
surface. “I use an auto rudder only and fly
right-right. On that model it’s off the
timer,” he says. “Since you never really fly
at max power, I don’t see the need for an
auto stab. Most of the time I can get three
flights out of a motor with no break-in.”
(Typically, F1B motors are wound to the
maximum limit and used only once;
broken strands after one winding areconsidered normal.)
“I fly the same torque by just adding
turns. This way I use 60-gram motors on
a 275-square-inch Mulvihill. It was an
easy way to take weight out of the model
by using a shorter motor tube.”
To connect that shorter, rolled-balsa
motor tube to the tail, Paul uses a carbonaluminum
tailboom. These are commonly
used for F1B models, which Paul also
flies. Typically, the booms are roughly
30-inches long and taper from
approximately ½ inch in diameter to
roughly 3/16 inch. The weight is roughly
7 grams.
Although the carbon-aluminum booms
are much lighter and stiffer than a rolledbalsa
boom, they are fragile and
occasionally break immediately in front
of the stabilizer or near the front
attachment point. Most who have flown
F1B for any time have a collection of
boom pieces that are approximately 18 to
24 inches. “Yes, I salvaged the tailboom
and coupling from an old Wake,” said
Paul.
Another interesting idea on Paul’s
model was the wing TE. A typical TE for
a model this size would be a piece of 1/8 x
½ balsa TE stock. A modern F1B aircraft
would use a thin carbon-fiber rectangle,
roughly .5 x 2.8mm (approximately .02 x
.11 inches) in size, tied to the carbonfiber
D-box with balsa ribs capped top
and bottom with thin (.003 inch) carbonfiber
strips.
Paul used both balsa and carbon on his
TE. “The trailing edge is 0.125 x 0.20-
inch balsa capped with 0.003-inch carbon
on the front, top, and bottom. It tapers to
0.125 x 0.125 inches at the tip. The balsa
is around 6 pounds per cubic foot,” said
Paul.
The result is a TE that is stiffer than
either solid balsa or thin carbon strip.
“With the wide rib spacing I use, you
need a stiffer trailing edge,” he said. “If
you use the small cross-section F1B
trailing edge, you must use carbon-fiber
cap strips to hold them to the ribs, which
adds weight.”
E-30 Short Kit: Don DeLoach has
added another model to his stable of
short kits. This one is the Super Pearl
202E. “It’s not a Mini Pearl,” said Don.
“It’s an all-new design with different
moments, airfoils, and, most
importantly, a much stiffer construction,
designed for plastic coverings and high
speed.”
Intended for the National Free Flight
Society (NFFS) E-36 event, it spans 34¾
inches with a wing area of 202 square
inches. The prototype, covered with ¾
mil Mylar, weighed in at 135 grams
ready to fly.
What is a short kit? A traditional kit
includes all of the wood needed, the
plans, some other hardware, and usually
the covering. The modeler supplies the
glue, dope, engine, etc. A short kit
typically includes ribs and some other
parts. You supply the long stuff: balsa
strip for wing and stabilizer LEs, TEs,
spars, and fuselage sheet wood.
Covering material, engine, and other
hardware must be provided by the
builder. Sometimes the plans are
included in a short kit and sometimes
they’re sold separately.
The Super Pearl 202E short kit
includes 115 laser-cut balsa parts such as
wing and stabilizer ribs and pylon
formers. Also included are some lasercut
plywood pieces. You will need to
supply strip balsa for wing and stabilizer
construction, sheet balsa for the fin and
pylon sides, and the carbon boom for the
fuselage.
The plans are sold separately,
allowing you to order two or more short
kits of ribs and only have to pay for one
set of plans. The short kit is $18 and the
plans are $6. Shipping is an additional
$6.
The fuselage is a 32-inch taperedcarbon-fiber boom similar to those used
for discus-launch gliders. Don suggested
sources for the boom as well as motor,
propeller, and other electronics. Total
cost to get a model in the air should be
approximately $100, not counting
shipping. You’ll also need a battery
charger/balancer ($30).
The recommended motor is the AX-
1806N 2500 Kv outrunner from Hobby
King. The recommended propeller setup
is a pair of 7.5 x 4 Graupner blades in a
folding hub, all from Texas Timers. The
battery is a Thunder Power 325 mAh, 2S
(7.4 volt) 65C from RC LiPos.
You can find the rules for the E-36
event at the NFFS website. NFFS also
offers plans for two other E-36 designs:
John Oldenkamp’s JouleBox E-36,
which won the 2011 Nats, and Hal
Cover’s Short Circuit, winner of the
2011 Issacson meet at Lost Hills,
California.
2011 Nats DVD: Alan Abriss spent a
week at the Nats filming the action. The
result is a 115-minute video that shows a
wide variety of outdoor FF activities,
including Electric, Dawn Unlimited, and
ROW. Also included is footage of some
of the Flying Aces Scale events and a
video shot from a model in flight.
The 2011 Free Flight National
Championships DVD is $20 plus $4
shipping and handling. You can order it
from the Homegrown Productions
website using a credit card or by mail
from Alan Abriss, 94-20 66th Ave., Suite
1G, Rego Park NY 11374. Make checkspayable to Alan Abriss. MA
Edition: Model Aviation - 2012/02
Page Numbers: 122,123,124,125
122 MODEL AVIATION
New ideas from the Nats
[[email protected]]
Free Flight Duration Louis Joyner
IDEAS: One of the many reasons for
going to the Nats, or any big contest, is to
get ideas. For those of us without a local
club, contests often offer the only way to
examine models firsthand and to discuss
design and construction ideas.
A firsthand look is especially helpful if
you are thinking about trying a new event.
Most modelers are willing to share what
they do and how they do it—just not
during the heat of competition. Pick the
lulls in activity to ask the detailed
questions and take a close look at models
and field equipment. Take notes and use a
camera to record details.
Here are a few ideas I picked up at last
year’s Nats.
A P-30 with Punch: Ross Jahnke had a
nice-looking P-30 that used a timeroperated
auto stabilizer to help control the
power burst. While auto stabilizers are
almost universally used in F1B Wakefield,
and fairly common for F1G Coupes, they
are not often seen in the AMA Rubber
events such as P-30, Mulvihill, and
Moffett.
An auto stabilizer holds the stabilizer’s
TE down slightly at launch, decreasing the
decalage (difference between the wing and
stabilizer incidence). This helps reduce the
looping tendency during the high-speed
phase of the motor run. After a few
seconds the stabilizer’s TE comes up to the
glide position for the cruise portion of the
climb and for the glide.
The main benefit of using an auto
stabilizer is the much straighter and more
vertical climb during the burst. For a
model with a relatively short motor run,
such as an F1B or F1G, a significant
percentage of the rubber motor’s total
energy is released in the first few seconds.
It is important that this energy is used to
get the model as high as possible. That
means a hard launch, and a never-vertical
climb for the first 3 to 4 seconds,
transitioning into a spiral climb.
A typical Wakefield might gain a third
of the total altitude in the first 4 seconds
and be at half of its final altitude at 12
seconds; the rest of the height gain takes
longer, perhaps another 30 seconds or
more.
For models with longer motor runs,
such as Mulvihill, Moffett, and most
Nostalgia and Old-Timer models, the burst
is still there, but it is a lower percentage of
the total stored energy. For these models, a
spiral climb and a longer motor run allow
good altitude gain without the need for
auto surfaces. Often P-30s have motor runs
of 90 seconds or more.
Ross’ P-30 uses a shorter, thicker
motor: six strands of 1/8-inch rubber. This
gives a maximum torque of 15 inch-ounces
at approximately 1,100 turns and a motor
run of approximately 30 to 40 seconds.
“I have tried to reduce frontal area to
climb fast,” he said. “It is a rocket and I
can throw it as hard as I would throw an
F1B. The general comment I get from
bystanders is how fast my P-30s climb.”
On his P-30, Ross uses the auto
stabilizer to control the fast initial climb
and prevent looping. A viscous timer
mounted in the pylon controls both the
auto stabilizer and DT. “The auto stab
kicks in at around 5 to 7 seconds; there is
very little deflection but it smoothes out
the first part of the climb,” said Ross.
There are advantages and disadvantages
to a short motor run and fast climb. The
most important advantage is the ability to
Paul Crowley’s rubber-powered
Mulvihill is a result of his halfcentury
of F1B Wakefield
experience. It uses a short rolled
balsa motor tube and a lightweight
carbon-aluminum tailboom
salvaged from an old F1B.
A viscous timer mounted in the pylon triggers
the auto stabilizer and the pop-up wing DT.
The wing is covered with Polyspan on the top
and bottom back to the spar for extra strength.
Instead of the usual balsa TE, Crowley’s
model uses a 1/8-inch-thick balsa strip
with thin carbon fiber attached to front,
top, and bottom. The result is
lightweight and stiff.
02sig4.QXD_00MSTRPG.QXD 12/16/11 4:45 PM Page 122get the model up through ground
turbulence, which can play havoc with the
power pattern of a slower-climbing model.
This is especially important on windy days
when the flightline is often located
downwind of a tree line. For a P-30 with
the required freewheeling propeller, using
a long motor run means more time under
power and less time gliding with the extra
drag of a freewheeling propeller.
Ross’ P-30 design dates back two
decades. “The name of the design is Quick
One and this is number 10 in the series. It
has evolved since the first one was built on
1981,” he said. “Quick Ones numbers 4
and 5 were published in the July 1989 MA.
If you look back at the article you will see
that the things I have kept are the forward
DT system and the flat center section of
the wing. There has been a steady
evolution. If you saw each model, the
continuity would be evident.”
Wakefield Inspired: Paul Crowley’s
Mulvihill model also makes use of an auto
surface. “I use an auto rudder only and fly
right-right. On that model it’s off the
timer,” he says. “Since you never really fly
at max power, I don’t see the need for an
auto stab. Most of the time I can get three
flights out of a motor with no break-in.”
(Typically, F1B motors are wound to the
maximum limit and used only once;
broken strands after one winding areconsidered normal.)
“I fly the same torque by just adding
turns. This way I use 60-gram motors on
a 275-square-inch Mulvihill. It was an
easy way to take weight out of the model
by using a shorter motor tube.”
To connect that shorter, rolled-balsa
motor tube to the tail, Paul uses a carbonaluminum
tailboom. These are commonly
used for F1B models, which Paul also
flies. Typically, the booms are roughly
30-inches long and taper from
approximately ½ inch in diameter to
roughly 3/16 inch. The weight is roughly
7 grams.
Although the carbon-aluminum booms
are much lighter and stiffer than a rolledbalsa
boom, they are fragile and
occasionally break immediately in front
of the stabilizer or near the front
attachment point. Most who have flown
F1B for any time have a collection of
boom pieces that are approximately 18 to
24 inches. “Yes, I salvaged the tailboom
and coupling from an old Wake,” said
Paul.
Another interesting idea on Paul’s
model was the wing TE. A typical TE for
a model this size would be a piece of 1/8 x
½ balsa TE stock. A modern F1B aircraft
would use a thin carbon-fiber rectangle,
roughly .5 x 2.8mm (approximately .02 x
.11 inches) in size, tied to the carbonfiber
D-box with balsa ribs capped top
and bottom with thin (.003 inch) carbonfiber
strips.
Paul used both balsa and carbon on his
TE. “The trailing edge is 0.125 x 0.20-
inch balsa capped with 0.003-inch carbon
on the front, top, and bottom. It tapers to
0.125 x 0.125 inches at the tip. The balsa
is around 6 pounds per cubic foot,” said
Paul.
The result is a TE that is stiffer than
either solid balsa or thin carbon strip.
“With the wide rib spacing I use, you
need a stiffer trailing edge,” he said. “If
you use the small cross-section F1B
trailing edge, you must use carbon-fiber
cap strips to hold them to the ribs, which
adds weight.”
E-30 Short Kit: Don DeLoach has
added another model to his stable of
short kits. This one is the Super Pearl
202E. “It’s not a Mini Pearl,” said Don.
“It’s an all-new design with different
moments, airfoils, and, most
importantly, a much stiffer construction,
designed for plastic coverings and high
speed.”
Intended for the National Free Flight
Society (NFFS) E-36 event, it spans 34¾
inches with a wing area of 202 square
inches. The prototype, covered with ¾
mil Mylar, weighed in at 135 grams
ready to fly.
What is a short kit? A traditional kit
includes all of the wood needed, the
plans, some other hardware, and usually
the covering. The modeler supplies the
glue, dope, engine, etc. A short kit
typically includes ribs and some other
parts. You supply the long stuff: balsa
strip for wing and stabilizer LEs, TEs,
spars, and fuselage sheet wood.
Covering material, engine, and other
hardware must be provided by the
builder. Sometimes the plans are
included in a short kit and sometimes
they’re sold separately.
The Super Pearl 202E short kit
includes 115 laser-cut balsa parts such as
wing and stabilizer ribs and pylon
formers. Also included are some lasercut
plywood pieces. You will need to
supply strip balsa for wing and stabilizer
construction, sheet balsa for the fin and
pylon sides, and the carbon boom for the
fuselage.
The plans are sold separately,
allowing you to order two or more short
kits of ribs and only have to pay for one
set of plans. The short kit is $18 and the
plans are $6. Shipping is an additional
$6.
The fuselage is a 32-inch taperedcarbon-fiber boom similar to those used
for discus-launch gliders. Don suggested
sources for the boom as well as motor,
propeller, and other electronics. Total
cost to get a model in the air should be
approximately $100, not counting
shipping. You’ll also need a battery
charger/balancer ($30).
The recommended motor is the AX-
1806N 2500 Kv outrunner from Hobby
King. The recommended propeller setup
is a pair of 7.5 x 4 Graupner blades in a
folding hub, all from Texas Timers. The
battery is a Thunder Power 325 mAh, 2S
(7.4 volt) 65C from RC LiPos.
You can find the rules for the E-36
event at the NFFS website. NFFS also
offers plans for two other E-36 designs:
John Oldenkamp’s JouleBox E-36,
which won the 2011 Nats, and Hal
Cover’s Short Circuit, winner of the
2011 Issacson meet at Lost Hills,
California.
2011 Nats DVD: Alan Abriss spent a
week at the Nats filming the action. The
result is a 115-minute video that shows a
wide variety of outdoor FF activities,
including Electric, Dawn Unlimited, and
ROW. Also included is footage of some
of the Flying Aces Scale events and a
video shot from a model in flight.
The 2011 Free Flight National
Championships DVD is $20 plus $4
shipping and handling. You can order it
from the Homegrown Productions
website using a credit card or by mail
from Alan Abriss, 94-20 66th Ave., Suite
1G, Rego Park NY 11374. Make checkspayable to Alan Abriss. MA
Edition: Model Aviation - 2012/02
Page Numbers: 122,123,124,125
122 MODEL AVIATION
New ideas from the Nats
[[email protected]]
Free Flight Duration Louis Joyner
IDEAS: One of the many reasons for
going to the Nats, or any big contest, is to
get ideas. For those of us without a local
club, contests often offer the only way to
examine models firsthand and to discuss
design and construction ideas.
A firsthand look is especially helpful if
you are thinking about trying a new event.
Most modelers are willing to share what
they do and how they do it—just not
during the heat of competition. Pick the
lulls in activity to ask the detailed
questions and take a close look at models
and field equipment. Take notes and use a
camera to record details.
Here are a few ideas I picked up at last
year’s Nats.
A P-30 with Punch: Ross Jahnke had a
nice-looking P-30 that used a timeroperated
auto stabilizer to help control the
power burst. While auto stabilizers are
almost universally used in F1B Wakefield,
and fairly common for F1G Coupes, they
are not often seen in the AMA Rubber
events such as P-30, Mulvihill, and
Moffett.
An auto stabilizer holds the stabilizer’s
TE down slightly at launch, decreasing the
decalage (difference between the wing and
stabilizer incidence). This helps reduce the
looping tendency during the high-speed
phase of the motor run. After a few
seconds the stabilizer’s TE comes up to the
glide position for the cruise portion of the
climb and for the glide.
The main benefit of using an auto
stabilizer is the much straighter and more
vertical climb during the burst. For a
model with a relatively short motor run,
such as an F1B or F1G, a significant
percentage of the rubber motor’s total
energy is released in the first few seconds.
It is important that this energy is used to
get the model as high as possible. That
means a hard launch, and a never-vertical
climb for the first 3 to 4 seconds,
transitioning into a spiral climb.
A typical Wakefield might gain a third
of the total altitude in the first 4 seconds
and be at half of its final altitude at 12
seconds; the rest of the height gain takes
longer, perhaps another 30 seconds or
more.
For models with longer motor runs,
such as Mulvihill, Moffett, and most
Nostalgia and Old-Timer models, the burst
is still there, but it is a lower percentage of
the total stored energy. For these models, a
spiral climb and a longer motor run allow
good altitude gain without the need for
auto surfaces. Often P-30s have motor runs
of 90 seconds or more.
Ross’ P-30 uses a shorter, thicker
motor: six strands of 1/8-inch rubber. This
gives a maximum torque of 15 inch-ounces
at approximately 1,100 turns and a motor
run of approximately 30 to 40 seconds.
“I have tried to reduce frontal area to
climb fast,” he said. “It is a rocket and I
can throw it as hard as I would throw an
F1B. The general comment I get from
bystanders is how fast my P-30s climb.”
On his P-30, Ross uses the auto
stabilizer to control the fast initial climb
and prevent looping. A viscous timer
mounted in the pylon controls both the
auto stabilizer and DT. “The auto stab
kicks in at around 5 to 7 seconds; there is
very little deflection but it smoothes out
the first part of the climb,” said Ross.
There are advantages and disadvantages
to a short motor run and fast climb. The
most important advantage is the ability to
Paul Crowley’s rubber-powered
Mulvihill is a result of his halfcentury
of F1B Wakefield
experience. It uses a short rolled
balsa motor tube and a lightweight
carbon-aluminum tailboom
salvaged from an old F1B.
A viscous timer mounted in the pylon triggers
the auto stabilizer and the pop-up wing DT.
The wing is covered with Polyspan on the top
and bottom back to the spar for extra strength.
Instead of the usual balsa TE, Crowley’s
model uses a 1/8-inch-thick balsa strip
with thin carbon fiber attached to front,
top, and bottom. The result is
lightweight and stiff.
02sig4.QXD_00MSTRPG.QXD 12/16/11 4:45 PM Page 122get the model up through ground
turbulence, which can play havoc with the
power pattern of a slower-climbing model.
This is especially important on windy days
when the flightline is often located
downwind of a tree line. For a P-30 with
the required freewheeling propeller, using
a long motor run means more time under
power and less time gliding with the extra
drag of a freewheeling propeller.
Ross’ P-30 design dates back two
decades. “The name of the design is Quick
One and this is number 10 in the series. It
has evolved since the first one was built on
1981,” he said. “Quick Ones numbers 4
and 5 were published in the July 1989 MA.
If you look back at the article you will see
that the things I have kept are the forward
DT system and the flat center section of
the wing. There has been a steady
evolution. If you saw each model, the
continuity would be evident.”
Wakefield Inspired: Paul Crowley’s
Mulvihill model also makes use of an auto
surface. “I use an auto rudder only and fly
right-right. On that model it’s off the
timer,” he says. “Since you never really fly
at max power, I don’t see the need for an
auto stab. Most of the time I can get three
flights out of a motor with no break-in.”
(Typically, F1B motors are wound to the
maximum limit and used only once;
broken strands after one winding areconsidered normal.)
“I fly the same torque by just adding
turns. This way I use 60-gram motors on
a 275-square-inch Mulvihill. It was an
easy way to take weight out of the model
by using a shorter motor tube.”
To connect that shorter, rolled-balsa
motor tube to the tail, Paul uses a carbonaluminum
tailboom. These are commonly
used for F1B models, which Paul also
flies. Typically, the booms are roughly
30-inches long and taper from
approximately ½ inch in diameter to
roughly 3/16 inch. The weight is roughly
7 grams.
Although the carbon-aluminum booms
are much lighter and stiffer than a rolledbalsa
boom, they are fragile and
occasionally break immediately in front
of the stabilizer or near the front
attachment point. Most who have flown
F1B for any time have a collection of
boom pieces that are approximately 18 to
24 inches. “Yes, I salvaged the tailboom
and coupling from an old Wake,” said
Paul.
Another interesting idea on Paul’s
model was the wing TE. A typical TE for
a model this size would be a piece of 1/8 x
½ balsa TE stock. A modern F1B aircraft
would use a thin carbon-fiber rectangle,
roughly .5 x 2.8mm (approximately .02 x
.11 inches) in size, tied to the carbonfiber
D-box with balsa ribs capped top
and bottom with thin (.003 inch) carbonfiber
strips.
Paul used both balsa and carbon on his
TE. “The trailing edge is 0.125 x 0.20-
inch balsa capped with 0.003-inch carbon
on the front, top, and bottom. It tapers to
0.125 x 0.125 inches at the tip. The balsa
is around 6 pounds per cubic foot,” said
Paul.
The result is a TE that is stiffer than
either solid balsa or thin carbon strip.
“With the wide rib spacing I use, you
need a stiffer trailing edge,” he said. “If
you use the small cross-section F1B
trailing edge, you must use carbon-fiber
cap strips to hold them to the ribs, which
adds weight.”
E-30 Short Kit: Don DeLoach has
added another model to his stable of
short kits. This one is the Super Pearl
202E. “It’s not a Mini Pearl,” said Don.
“It’s an all-new design with different
moments, airfoils, and, most
importantly, a much stiffer construction,
designed for plastic coverings and high
speed.”
Intended for the National Free Flight
Society (NFFS) E-36 event, it spans 34¾
inches with a wing area of 202 square
inches. The prototype, covered with ¾
mil Mylar, weighed in at 135 grams
ready to fly.
What is a short kit? A traditional kit
includes all of the wood needed, the
plans, some other hardware, and usually
the covering. The modeler supplies the
glue, dope, engine, etc. A short kit
typically includes ribs and some other
parts. You supply the long stuff: balsa
strip for wing and stabilizer LEs, TEs,
spars, and fuselage sheet wood.
Covering material, engine, and other
hardware must be provided by the
builder. Sometimes the plans are
included in a short kit and sometimes
they’re sold separately.
The Super Pearl 202E short kit
includes 115 laser-cut balsa parts such as
wing and stabilizer ribs and pylon
formers. Also included are some lasercut
plywood pieces. You will need to
supply strip balsa for wing and stabilizer
construction, sheet balsa for the fin and
pylon sides, and the carbon boom for the
fuselage.
The plans are sold separately,
allowing you to order two or more short
kits of ribs and only have to pay for one
set of plans. The short kit is $18 and the
plans are $6. Shipping is an additional
$6.
The fuselage is a 32-inch taperedcarbon-fiber boom similar to those used
for discus-launch gliders. Don suggested
sources for the boom as well as motor,
propeller, and other electronics. Total
cost to get a model in the air should be
approximately $100, not counting
shipping. You’ll also need a battery
charger/balancer ($30).
The recommended motor is the AX-
1806N 2500 Kv outrunner from Hobby
King. The recommended propeller setup
is a pair of 7.5 x 4 Graupner blades in a
folding hub, all from Texas Timers. The
battery is a Thunder Power 325 mAh, 2S
(7.4 volt) 65C from RC LiPos.
You can find the rules for the E-36
event at the NFFS website. NFFS also
offers plans for two other E-36 designs:
John Oldenkamp’s JouleBox E-36,
which won the 2011 Nats, and Hal
Cover’s Short Circuit, winner of the
2011 Issacson meet at Lost Hills,
California.
2011 Nats DVD: Alan Abriss spent a
week at the Nats filming the action. The
result is a 115-minute video that shows a
wide variety of outdoor FF activities,
including Electric, Dawn Unlimited, and
ROW. Also included is footage of some
of the Flying Aces Scale events and a
video shot from a model in flight.
The 2011 Free Flight National
Championships DVD is $20 plus $4
shipping and handling. You can order it
from the Homegrown Productions
website using a credit card or by mail
from Alan Abriss, 94-20 66th Ave., Suite
1G, Rego Park NY 11374. Make checkspayable to Alan Abriss. MA
