BIG, POWERFUL aircraft tend to get
the most attention at any model meet,
yet most of the sport airplanes are
smaller. The same holds true in jet
modeling. Big jets draw the most
interest, so guess what? We don’t hear a
lot about small turbine-powered jets.
The smallest turbine on the popular
market has been the Wren 44. I have
seen it power quite a few nice jets. Gary
Arthur and Marc Thomson attended the
fall Winamac, Indiana, event with some
fine-flying Wren 44-powered machines:
a pair of scale Savex L-39 Albatroses
and a Yellow Aircraft Stingray. Their
performance is as impressive as that of
any turbine model. They are neat
machines.
The Savex L-39 Albatros is 1/8 scale
and typically weighs less than 10
pounds. Powered by the 10-poundthrust
Wren 44, the roughly 1:1 powerto-
weight ratio makes for impressive
performance.
The L-39’s wingspan is 48 inches,
and it is only 59 inches long. Its
convenient size makes it easy to
transport, yet it’s powerful enough to
handle windy weather conditions.
Check out the Savex Web site, shown in
the source listing, for additional
information.
The full-scale L-39 Albatros has
become a popular sport aircraft. It can
be modeled in a wide variety of paint
schemes ranging from military themes
to some wild civilian paint designs. You
can have fun building and flying this
model.
The sharp Yellow Aircraft Stingray
is rarely seen at jet meets. Powered by a
Wren 44, it boasts a great combination
of power and airframe. The small
turbine helps keep the weight down to
10.5 pounds, and the Stingray looked
right flying at this weight.
This model’s performance is as good
as that of any delta-wing sport jet. Its
high-speed flight is impressive; it looks
fast because it is.
The landing speed is the main
advantage of using the lightweight
Wren 44 on the Stingray. Its landingapproach
speed matched that of any
sport jet. As a small model, the Stingray
is unforgiving to weight gains. Many
are powered with heavy, more powerful
turbines, and the associated high
landing speeds have been an issue.
Yellow Aircraft has been selling the
52-inch-wingspan Stingray. It is
intended to introduce modelers to
turbine flying. The engine is mounted
aft and above the wing for easy access.
See the source listing for additional
information.
Jeff Minotti is doing some exciting
things up here in northeast Ohio. He
has been building a selection of
homebuilt turbines for a few years. He
has had success running them, and as a
Gas Turbine Builders Association
(GTBA) member he has shared his
experiences with others throughout the
world. The Internet makes
communication worldwide a practical
and educational experience.
Jeff has been developing his flying
skills with a variety of ducted-fan and
performance sport aircraft in
preparation for his first turbinepowered
model and has joined the jetmodeling
community. He got his
turbine waiver, had his first homebuilt
turbine approved by AMA for flight,
and then went out and flew it.
Jeff allowed me to test-fly his
modified Balsa USA Enforcer powered
by a 10-pound-thrust turbine. His
previous experience with the Enforcer
as a ducted-fan jet proved itself on the
test flight. The control throws, CG, and
general setup were perfect. It required
no changes, and the flight was sweet.
Jeff took the second flight.
I was impressed by how smoothly
his turbine ran. It had one of the most
even fuel burns I have seen or heard in
one of these engines. It made me realize
how much of a difference in sound
there is when a turbine is “right.” Not
many commercial turbines sound as
smooth as his. Great job, Jeff!
Let’s discuss a flying skill: the art of
the low pass. I am not referring to those
descents that finish with a hard pull up
before hitting the ground. I have in
mind that level photo pass down the
runway for a couple hundred feet. The
altitude might be 20 or merely 2 feet above the ground, but the airplane is
under perfect control in level flight. It is
a wonderful display of precision flying.
In Scale competition the low pass is
recognized as a precision maneuver
called the “Flyby.” It’s judged at cruise
speed and as a slow pass displaying the
airplane in the down-and-dirty
configuration with landing gear and flaps
extended.
How do you make such a pretty pass?
It takes setup and developed skill.
You have to trim your aircraft well;
pitch and roll trim must be dead-on. The
ground is like a straightedge, measuring
how accurately you draw a straight line
with your model. Most people who have
trouble with a low pass are fighting an
out-of-trim condition with their aircraft.
Take your time to accurately trim for
pitch and roll. At altitude set the jet level
and remove your hand from the stick. It
should fly a couple hundred feet without
varying in either roll or pitch. If your
model is not trimmed this precisely, you
will fight it all the time.
Once you have the trims set up, you
have to learn to position and point your
jet accurately. What do I mean by this?
Do you trim your aircraft for a slight
dive so you correct regularly with upelevator?
This is a typical trim setup that
compensates for inaccurate level flight
when rolling out of turns. You pull up
out of the turn and allow the downelevator
trim to lower the model’s nose
until you achieve the flight level you
want, and then you tap some up-elevator
to level off.
This is a sloppy technique. When you
make a low pass, that pitch correction
will be obvious. The ground makes an
accurate gauge, and the lower your pass,
the more visible your careless technique
will be.
After your jet is trimmed for level
flight, concentrate on rolling out of turns
without climbing. Criteria that must be
met as you roll out of a turn are position
relative to the runway, altitude above the
ground, heading parallel to the runway,
and climbing or diving.
Normally you want to nail your jet’s
position and heading as it rolls out of a
turn, yet have it come out of the turn in a
slight descent. A perfectly trimmed
model will continue that descent until
you stop it with a breath of up-elevator
as you reach the altitude you want. This
is similar to that down-elevator trim
philosophy of flight, only you
consciously point the model in a slight
descent as you roll out of the turn.
If you have completed rolling out of
the turn, all you have to do is stop the
descent at the right altitude and position
to start the low pass. When you pull on
the elevator, the goal is to achieve level
flight relative to the ground and then
release the controls and enjoy the view
of your jet as it flies by.
That is where the time spent
accurately trimming it for level flight
will be appreciated. No more corrections
should be required.
It may seem simple as you read this,
but applying the theory in flight is
difficult. Every turn you make while
flying a model is an opportunity to
practice positioning it accurately—not
only its position in the sky, but its
heading parallel to the flightline,
altitude, and angle of descent.
The better you are at using the turn
maneuver to position your jet, the better
and easier your flying will be. Just as
you use the turn on final to land your
model on the runway heading, every turn
is used to similarly align the aircraft and
set up for something else such as a pass
or maneuver.
The supposedly simple low pass, or
Flyby, is a result of proper aircraft setup
and trim followed by precision flying
skills that begin with a turn that properly
aligns the model. The low pass itself is
merely the reward for the previous hard
work.
Practicing these flying techniques will
greatly improve your flying skills, which
will in turn reduce the pilot workload,
particularly when flying jets at higher
speeds. Poor heading and pointing of
your aircraft when coming out of turns
makes flying high-speed aircraft
difficult. You end up following behind
the model, trying to keep it within a
reasonable distance from yourself rather
than enjoying the thrill of high-speed
flight.
It is time to get back to the building
board. My T-33 is getting an upgrade to
its landing gear, and who knows what
else I will build this winter? See you at
the jet meets. MA
Sources:
Savex
(+420) 377240464
www.savex.cz
Yellow Aircraft
(781) 935-9868
www.yellowaircraft.com
Edition: Model Aviation - 2008/02
Page Numbers: 144,145
Edition: Model Aviation - 2008/02
Page Numbers: 144,145
BIG, POWERFUL aircraft tend to get
the most attention at any model meet,
yet most of the sport airplanes are
smaller. The same holds true in jet
modeling. Big jets draw the most
interest, so guess what? We don’t hear a
lot about small turbine-powered jets.
The smallest turbine on the popular
market has been the Wren 44. I have
seen it power quite a few nice jets. Gary
Arthur and Marc Thomson attended the
fall Winamac, Indiana, event with some
fine-flying Wren 44-powered machines:
a pair of scale Savex L-39 Albatroses
and a Yellow Aircraft Stingray. Their
performance is as impressive as that of
any turbine model. They are neat
machines.
The Savex L-39 Albatros is 1/8 scale
and typically weighs less than 10
pounds. Powered by the 10-poundthrust
Wren 44, the roughly 1:1 powerto-
weight ratio makes for impressive
performance.
The L-39’s wingspan is 48 inches,
and it is only 59 inches long. Its
convenient size makes it easy to
transport, yet it’s powerful enough to
handle windy weather conditions.
Check out the Savex Web site, shown in
the source listing, for additional
information.
The full-scale L-39 Albatros has
become a popular sport aircraft. It can
be modeled in a wide variety of paint
schemes ranging from military themes
to some wild civilian paint designs. You
can have fun building and flying this
model.
The sharp Yellow Aircraft Stingray
is rarely seen at jet meets. Powered by a
Wren 44, it boasts a great combination
of power and airframe. The small
turbine helps keep the weight down to
10.5 pounds, and the Stingray looked
right flying at this weight.
This model’s performance is as good
as that of any delta-wing sport jet. Its
high-speed flight is impressive; it looks
fast because it is.
The landing speed is the main
advantage of using the lightweight
Wren 44 on the Stingray. Its landingapproach
speed matched that of any
sport jet. As a small model, the Stingray
is unforgiving to weight gains. Many
are powered with heavy, more powerful
turbines, and the associated high
landing speeds have been an issue.
Yellow Aircraft has been selling the
52-inch-wingspan Stingray. It is
intended to introduce modelers to
turbine flying. The engine is mounted
aft and above the wing for easy access.
See the source listing for additional
information.
Jeff Minotti is doing some exciting
things up here in northeast Ohio. He
has been building a selection of
homebuilt turbines for a few years. He
has had success running them, and as a
Gas Turbine Builders Association
(GTBA) member he has shared his
experiences with others throughout the
world. The Internet makes
communication worldwide a practical
and educational experience.
Jeff has been developing his flying
skills with a variety of ducted-fan and
performance sport aircraft in
preparation for his first turbinepowered
model and has joined the jetmodeling
community. He got his
turbine waiver, had his first homebuilt
turbine approved by AMA for flight,
and then went out and flew it.
Jeff allowed me to test-fly his
modified Balsa USA Enforcer powered
by a 10-pound-thrust turbine. His
previous experience with the Enforcer
as a ducted-fan jet proved itself on the
test flight. The control throws, CG, and
general setup were perfect. It required
no changes, and the flight was sweet.
Jeff took the second flight.
I was impressed by how smoothly
his turbine ran. It had one of the most
even fuel burns I have seen or heard in
one of these engines. It made me realize
how much of a difference in sound
there is when a turbine is “right.” Not
many commercial turbines sound as
smooth as his. Great job, Jeff!
Let’s discuss a flying skill: the art of
the low pass. I am not referring to those
descents that finish with a hard pull up
before hitting the ground. I have in
mind that level photo pass down the
runway for a couple hundred feet. The
altitude might be 20 or merely 2 feet above the ground, but the airplane is
under perfect control in level flight. It is
a wonderful display of precision flying.
In Scale competition the low pass is
recognized as a precision maneuver
called the “Flyby.” It’s judged at cruise
speed and as a slow pass displaying the
airplane in the down-and-dirty
configuration with landing gear and flaps
extended.
How do you make such a pretty pass?
It takes setup and developed skill.
You have to trim your aircraft well;
pitch and roll trim must be dead-on. The
ground is like a straightedge, measuring
how accurately you draw a straight line
with your model. Most people who have
trouble with a low pass are fighting an
out-of-trim condition with their aircraft.
Take your time to accurately trim for
pitch and roll. At altitude set the jet level
and remove your hand from the stick. It
should fly a couple hundred feet without
varying in either roll or pitch. If your
model is not trimmed this precisely, you
will fight it all the time.
Once you have the trims set up, you
have to learn to position and point your
jet accurately. What do I mean by this?
Do you trim your aircraft for a slight
dive so you correct regularly with upelevator?
This is a typical trim setup that
compensates for inaccurate level flight
when rolling out of turns. You pull up
out of the turn and allow the downelevator
trim to lower the model’s nose
until you achieve the flight level you
want, and then you tap some up-elevator
to level off.
This is a sloppy technique. When you
make a low pass, that pitch correction
will be obvious. The ground makes an
accurate gauge, and the lower your pass,
the more visible your careless technique
will be.
After your jet is trimmed for level
flight, concentrate on rolling out of turns
without climbing. Criteria that must be
met as you roll out of a turn are position
relative to the runway, altitude above the
ground, heading parallel to the runway,
and climbing or diving.
Normally you want to nail your jet’s
position and heading as it rolls out of a
turn, yet have it come out of the turn in a
slight descent. A perfectly trimmed
model will continue that descent until
you stop it with a breath of up-elevator
as you reach the altitude you want. This
is similar to that down-elevator trim
philosophy of flight, only you
consciously point the model in a slight
descent as you roll out of the turn.
If you have completed rolling out of
the turn, all you have to do is stop the
descent at the right altitude and position
to start the low pass. When you pull on
the elevator, the goal is to achieve level
flight relative to the ground and then
release the controls and enjoy the view
of your jet as it flies by.
That is where the time spent
accurately trimming it for level flight
will be appreciated. No more corrections
should be required.
It may seem simple as you read this,
but applying the theory in flight is
difficult. Every turn you make while
flying a model is an opportunity to
practice positioning it accurately—not
only its position in the sky, but its
heading parallel to the flightline,
altitude, and angle of descent.
The better you are at using the turn
maneuver to position your jet, the better
and easier your flying will be. Just as
you use the turn on final to land your
model on the runway heading, every turn
is used to similarly align the aircraft and
set up for something else such as a pass
or maneuver.
The supposedly simple low pass, or
Flyby, is a result of proper aircraft setup
and trim followed by precision flying
skills that begin with a turn that properly
aligns the model. The low pass itself is
merely the reward for the previous hard
work.
Practicing these flying techniques will
greatly improve your flying skills, which
will in turn reduce the pilot workload,
particularly when flying jets at higher
speeds. Poor heading and pointing of
your aircraft when coming out of turns
makes flying high-speed aircraft
difficult. You end up following behind
the model, trying to keep it within a
reasonable distance from yourself rather
than enjoying the thrill of high-speed
flight.
It is time to get back to the building
board. My T-33 is getting an upgrade to
its landing gear, and who knows what
else I will build this winter? See you at
the jet meets. MA
Sources:
Savex
(+420) 377240464
www.savex.cz
Yellow Aircraft
(781) 935-9868
www.yellowaircraft.com
