PETER C. OESTERWINTER
Plane Talk: Great Planes L-39 Albatros Jet EDF ARF
Above: Even though it’s fragile, the included
stand looks good and is a great way to display
the L-39 at home or at the office.
A dynamite package
for the park or field
The instructions make it clear not to use the drop tanks and missiles for flight—
but they looked so good, and magnets held them tight. The Albatros knew they
were there.
AERO VODOCHODY Corporation in
Czechoslovakia designed and manufactured
the full-scale L-39. Even though it was
invented to be a trainer, the Albatros has also
seen duty as a light attack aircraft.
When looking at this striking jet, it’s hard
to believe that its design dates back to the
1960s, with its maiden flight taking place on
November 4, 1968. The design is so sound
that it evolved into the L-59 Super Albatros,
which is still in production.
With more than 2,800 still in service, the
Albatros has become available to private
buyers who are looking for a unique yet
pricey thrill ride. You can get one for
approximately $300,000. With the cost of
fuel these days, I hate to imagine how much it
costs to operate that thirsty little jet.
In its ElectriFly series, Great Planes has
successfully captured all of this awesome
aircraft’s beauty and scaled it down into a
well-engineered model. For a street price of
$99, you can pick up one of these little
beauties instead of the full-scale version and
save $299,901.
At a length of 31 inches, the ElectriFly L-
39 is 1:15 scale. It is molded from AeroCell: a
closed-cell EPP-foam material that is
lightweight, durable, and has a smooth finish
(compared to older foam materials). It is ideal
for the nice factory-applied scale paint
scheme.
Thanks to the low parts count, the
Albatros’s assembly process from box to air is
quick. My production sample took less than
three hours to get ready for flight.
Contents: The box containing the ElectriFly
L-39 Albatros was well decorated and well
presented. I spent quite a bit of time turning
the box in my hands, reading all of the
information printed on it. There were many
June 2009 75
06sig3.QXD 4/22/09 12:56 PM Page 75
76 MODEL AVIATION
Pluses and Minuses
+
• Excellent quality and parts fit.
• Quick assembly time.
• Accurate scale outline.
• Stunning performance in all flight envelopes.
• Attractive home-display stand is included.
-
• Paint adheres poorly to AeroCell foam and will come
off with normal use.
Specifications and Equipment Used
Type: Electric ducted fan sport-scale
Wingspan: 25 inches
Length: 31 inches
Weight: 17.5-18.5 ounces
Weight as flown: 17.9 ounces
Wing loading: 17.9-18.9 ounces/square foot
Radio required: Three channels (aileron, elevator,
throttle)
Motor: Ammo 20-40-3500
Radio: Futaba T6XA
Receiver: Corona RD620
Servos: Futaba S3114
ESC: ElectriFly Silver Series 25A
Battery: ElectriFly Power Series 3S 910 mAh
The model comes out of the box with parts individually bagged, to
prevent chafing of the clean paint finish. The HyperFlow fan unit and
Ammo motor are included.
To accommodate the 20mm Ammo brushless power plant, a
small amount of material needs to be trimmed from the mount.
The power system requires no soldering.
Static photos by the author Flight photos by Denise Donnolly and Tim Mangee
Two marks where flanges are located in the fuselage make it
easier to seat the HyperFlow fan in the correct location. Magnet
closures are used throughout.
Make sure that the motor leads are in their channels before
permanently securing the wing in place with epoxy. Scuff the parts
first.
06sig3.QXD 4/22/09 12:09 PM Page 76
June 2009 77
Below: The ARF is molded from EPP-style foam. The latest version of the Albatros—the
Rx-R—has a detailed cockpit and is made from AeroCell foam.
External dummy fuel tanks serve as landing skids. Oversized
inlets ensure that the HyperFlow fan breathes well. A 900 mAh
3S pack can offer more than eight minutes of flight time.
The author’s son, Josh, demonstrates his dad’s preferred launch
grip and stance. A fast, level toss, with the EDF throttle fully
open, will get the L-39 flying.
photos and diagrams and a great deal of
technical information to pour over.
Once I opened the box, I was delighted
with what was inside. All parts were
individually bagged and well packed. There
were four major airframe components:
fuselage, one-piece wing, stabilizer/elevator,
and vertical stabilizer.
Because AeroCell is naturally flexible,
the typical assembly step of hinging was not
required; all flying surfaces were molded in
one piece with the control surfaces attached.
The only thing I would do to them at this
point would be to flex the control surfaces to
free them a bit.
The Ammo brushless motor and
HyperFlow ducted fan combination was
included with its own instruction manual.
Hardware was also supplied, and it had
some good features I will explain later.
As I mentioned earlier, the paint was
applied superbly, and the panel lines were
not oversized—a feature I have seen on
other foam models. Simulated drop tanks,
tip tanks, and missiles were included and
attached by powerful rare earth magnets.
The tip tanks could stay, but the missiles
and drop tanks needed to be removed for
flight. The canopy was also held securely
in place by rare earth magnets.
The included display stand looked elegant
and was great for showing the L-39 at home,
but is a bit fragile, so handle with care.
Assembly: Locate the manual showing how
to assemble the HyperFlow fan unit. The steps
are clear and easy to follow.
Do not panic when examining all the parts;
the front housing flange is not provided, nor is
it required for the L-39. I was concerned
because that part was missing, but it is
required only if the fan unit is used in a
nacelle.
Several motor options are available for the
HyperFlow fan unit. Slight trimming was
needed to fit the included Ammo power plant,
and the flange was premolded to act as a
guide. Three fan rotor shaft adapters (2mm,
2.3mm, and 3mm) are provided; the Albatros
motor has a 2mm shaft. The 2mm fan rotor
adapter would not initially slide onto the
motor shaft, so I assumed that it was too small
and went with the 2.3mm adapter.
When I had the model completed and
ready for motor testing, at full power the
Ammo—and the entire airframe—vibrated
severely. This cost me the impeller and a lot
of time trying to figure out what was wrong.
Great Planes’ customer support promptly
provided me with a replacement fan, since, at
the time, I thought the fan was out of balance.
In actuality, the shaft adapter was wobbling.
The problem was that the 2mm fan rotor
adapter was milled a bit too tight. After I
performed a slight deburring, it slowly started
to cooperate and slide onto the shaft.
The L-39’s airframe was easy to complete.
Futaba’s S3114 servos fit perfectly into the
aileron servo bays, and the servo cables fit
directly into the molded servo-lead channels.
The instructions recommended cyanoacrylate
to secure the servos; however, I used lowtemperature
hot glue, because it does not
permanently scar the servo case and makes
them easier to remove later.
I enjoyed using the included thumbscrew
pushrod connector; it makes adjusting the
aileron to the pushrod easy. Once the ailerons
are centered, a quick twist with the fingers
locks them in place. Finger-tight is not
enough, so use a screwdriver to completely
secure them.
When the ailerons are centered, glue the
aileron pushrod covers in place. Foamfriendly
cyanoacrylate worked fine until the
first landing, when both covers popped off.
I have found an excellent adhesive by
06sig3.QXD 4/22/09 12:12 PM Page 77
Devcon called Plastic Welder. It is a two-part
epoxy but welds the material together similar
to plastic model cement. Epoxy should work
fine as well.
Two grooves that are molded into the
fuselage match the flanges on the fan housing
that need to be glued into place. To ensure
proper placement, use a pen to mark the
grooves’ locations on the inside edge of the
fuselage. Use 30-minute epoxy for this step.
The motor wires are fed through a hole
at the bottom of the fuselage, through a
channel in the wing saddle, and then
passed through another hole back into the
forward fuselage. Ensure that all wires are
inserted correctly before gluing the fan
assembly in place.
Apply 30-minute epoxy to the wing
saddle, and glue the wing directly to the
fuselage. Make sure that the motor wires and
aileron-servo cables are properly seated within
the wire channels. The alignment keys molded
into the wing and saddle assure that the wing
is positioned correctly.
Set the airframe aside with a weight on top
of the fuselage until the adhesive cures.
The horizontal stabilizer and vertical
stabilizer are glued in place with epoxy.
Scrape away the paint from the mounting
area, to provide a stronger bond. The elevator
servo sits nicely in a foam servo tray that is
glued in place at the factory.
My Corona RD620 receiver from BP
Hobbies worked well with the Futaba servos.
Inside the fuselage is a guide tube for the
servo antenna, but getting the antenna through
is a tight squeeze. I used needle-nose pliers
and pushed the antenna through 1/4 inch at a
time, to keep it from bunching up. A small
amount of light oil will help it slide through.
Because of the L-39’s small size, setting it
up for flight is critical. Make sure that the CG
is correct and that the control throws are set
exactly to what the instruction manual
recommends.
My model required .5 ounce of weight in
the nose to obtain the correct CG. The low
rate on the elevator looks small, but little
elevator throw is needed for this short-coupled
aircraft.
Flying: The L-39 flies wonderfully but is
tricky. Having someone with hand-launching
experience nearby would be helpful.
I did not have an assistant for my test
flights, so I was on my own. I had never tried
an underhanded launch before and found the
method a bit unorthodox, but the instruction
manual recommended it so I figured I’d try
anyway.
The L-39 came out of my hand much
slower than I thought it would, and I was flatout
surprised that it kept flying. That’s a
testament to this design’s excellent slowspeed
performance. The times I was unable to
give it the toss it needed clearly demonstrated
the AeroCell’s durability.
I was more comfortable with the standard
overhead toss, gripping the fuselage directly
forward of the wing. Once it left my hand, the
L-39 needed to build speed before
establishing a climb. Launching with a correct
angle, of what I found to be approximately
10° nose up, worked well—especially for the
first five seconds, since there was not much
airflow over the stabilizer to make it very
effective.
Once out of the low-speed takeoff
envelope, the Albatros opened up and went to
town. At full power, it slid through the air at a
good clip. Speed was not blistering; I
estimated a good 60 mph, which is just fast
enough for a little jet such as this, since it
could quickly fly out of sight.
The recommended low rate settings are
plenty for flying the L-39. The aileron high
rate setting is great for spectacular axial rolls
at a rate of roughly two-and-a-half revolutions
per second. I recommend using the low
setting for the aileron at first, when
familiarizing yourself with the flight
performance.
Flying inverted required a considerable
amount of down-elevator, so switching to the
high rate for inverted flight made life easier.
After several flights, I kept the low rate at the
recommended 1/8 inch for up but increased the
downswing to 5/16 inch.
All aerobatics are possible for an airframe
with aileron and elevator. Loops require a bit
of downhill first, but the loops are large and
look great. Outside loops are also large and
scale-looking, but make sure to have plenty of
airspeed before attempting them.
For a small electric-ducted-fan jet with
such a short wing, the slow-speed
performance and stability astonished me, as
proven with my first attempted hand launch.
The L-39 will slow nicely for realistic landing
approaches. It’s not a glider, and power still
needs to be carried in on the approach.
Flying the Albatros to when the BEC shuts
down the motor is a bad idea; with no power,
the nose needs to drop to maintain a flyable
airspeed. I like to manage my flight time and
leave enough battery power in case I need to
make a go-around.
Average flight times with the ElectriFly
three-cell, 900 mAh battery are in the
neighborhood of seven minutes. With good
power management, 10-minute flight times
are possible.
At the low elevator setting, it took some
effort to coax the L-39 into a stall. A full stall
will result in a sudden nose drop and require
approximately 15 feet of altitude to recover
(with full power). Be cautious if flying slowly
at the high rates, especially in turns, because a
stall can occur suddenly.
From box to flight, my Albatros was an
enjoyable project. Quality is excellent, all
parts fit well, and I had no trouble building it,
aside from my goof with the motor adapter.
Despite being a small scale jet, it is well
behaved. If you can handle an aileron/elevator
aircraft and want to bring some jet action to
your field, try the ElectriFly L-39. I doubt that
you will be disappointed with the quality,
looks, performance, or durability. MA
Peter C. Oesterwinter
[email protected]
Manufacturer/Distributor:
ElectriFly/Great Planes
Box 9021
Champaign IL 61826
(217) 398-3630
www.electrifly.com
Sources:
Futaba
(217) 398-3630
www.futaba-rc.com
BP Hobbies
(732) 287-3933
www.bphobbies.com
Devcon
(800) 933-8266
www.devcon.com
Other Published Reviews:
Backyard Flyer: September 2008
RC Sport Flyer: October 2008
R/C Report: October 2008
Fly RC: November 2008
Edition: Model Aviation - 2009/06
Page Numbers: 75,76,77,78
Edition: Model Aviation - 2009/06
Page Numbers: 75,76,77,78
PETER C. OESTERWINTER
Plane Talk: Great Planes L-39 Albatros Jet EDF ARF
Above: Even though it’s fragile, the included
stand looks good and is a great way to display
the L-39 at home or at the office.
A dynamite package
for the park or field
The instructions make it clear not to use the drop tanks and missiles for flight—
but they looked so good, and magnets held them tight. The Albatros knew they
were there.
AERO VODOCHODY Corporation in
Czechoslovakia designed and manufactured
the full-scale L-39. Even though it was
invented to be a trainer, the Albatros has also
seen duty as a light attack aircraft.
When looking at this striking jet, it’s hard
to believe that its design dates back to the
1960s, with its maiden flight taking place on
November 4, 1968. The design is so sound
that it evolved into the L-59 Super Albatros,
which is still in production.
With more than 2,800 still in service, the
Albatros has become available to private
buyers who are looking for a unique yet
pricey thrill ride. You can get one for
approximately $300,000. With the cost of
fuel these days, I hate to imagine how much it
costs to operate that thirsty little jet.
In its ElectriFly series, Great Planes has
successfully captured all of this awesome
aircraft’s beauty and scaled it down into a
well-engineered model. For a street price of
$99, you can pick up one of these little
beauties instead of the full-scale version and
save $299,901.
At a length of 31 inches, the ElectriFly L-
39 is 1:15 scale. It is molded from AeroCell: a
closed-cell EPP-foam material that is
lightweight, durable, and has a smooth finish
(compared to older foam materials). It is ideal
for the nice factory-applied scale paint
scheme.
Thanks to the low parts count, the
Albatros’s assembly process from box to air is
quick. My production sample took less than
three hours to get ready for flight.
Contents: The box containing the ElectriFly
L-39 Albatros was well decorated and well
presented. I spent quite a bit of time turning
the box in my hands, reading all of the
information printed on it. There were many
June 2009 75
06sig3.QXD 4/22/09 12:56 PM Page 75
76 MODEL AVIATION
Pluses and Minuses
+
• Excellent quality and parts fit.
• Quick assembly time.
• Accurate scale outline.
• Stunning performance in all flight envelopes.
• Attractive home-display stand is included.
-
• Paint adheres poorly to AeroCell foam and will come
off with normal use.
Specifications and Equipment Used
Type: Electric ducted fan sport-scale
Wingspan: 25 inches
Length: 31 inches
Weight: 17.5-18.5 ounces
Weight as flown: 17.9 ounces
Wing loading: 17.9-18.9 ounces/square foot
Radio required: Three channels (aileron, elevator,
throttle)
Motor: Ammo 20-40-3500
Radio: Futaba T6XA
Receiver: Corona RD620
Servos: Futaba S3114
ESC: ElectriFly Silver Series 25A
Battery: ElectriFly Power Series 3S 910 mAh
The model comes out of the box with parts individually bagged, to
prevent chafing of the clean paint finish. The HyperFlow fan unit and
Ammo motor are included.
To accommodate the 20mm Ammo brushless power plant, a
small amount of material needs to be trimmed from the mount.
The power system requires no soldering.
Static photos by the author Flight photos by Denise Donnolly and Tim Mangee
Two marks where flanges are located in the fuselage make it
easier to seat the HyperFlow fan in the correct location. Magnet
closures are used throughout.
Make sure that the motor leads are in their channels before
permanently securing the wing in place with epoxy. Scuff the parts
first.
06sig3.QXD 4/22/09 12:09 PM Page 76
June 2009 77
Below: The ARF is molded from EPP-style foam. The latest version of the Albatros—the
Rx-R—has a detailed cockpit and is made from AeroCell foam.
External dummy fuel tanks serve as landing skids. Oversized
inlets ensure that the HyperFlow fan breathes well. A 900 mAh
3S pack can offer more than eight minutes of flight time.
The author’s son, Josh, demonstrates his dad’s preferred launch
grip and stance. A fast, level toss, with the EDF throttle fully
open, will get the L-39 flying.
photos and diagrams and a great deal of
technical information to pour over.
Once I opened the box, I was delighted
with what was inside. All parts were
individually bagged and well packed. There
were four major airframe components:
fuselage, one-piece wing, stabilizer/elevator,
and vertical stabilizer.
Because AeroCell is naturally flexible,
the typical assembly step of hinging was not
required; all flying surfaces were molded in
one piece with the control surfaces attached.
The only thing I would do to them at this
point would be to flex the control surfaces to
free them a bit.
The Ammo brushless motor and
HyperFlow ducted fan combination was
included with its own instruction manual.
Hardware was also supplied, and it had
some good features I will explain later.
As I mentioned earlier, the paint was
applied superbly, and the panel lines were
not oversized—a feature I have seen on
other foam models. Simulated drop tanks,
tip tanks, and missiles were included and
attached by powerful rare earth magnets.
The tip tanks could stay, but the missiles
and drop tanks needed to be removed for
flight. The canopy was also held securely
in place by rare earth magnets.
The included display stand looked elegant
and was great for showing the L-39 at home,
but is a bit fragile, so handle with care.
Assembly: Locate the manual showing how
to assemble the HyperFlow fan unit. The steps
are clear and easy to follow.
Do not panic when examining all the parts;
the front housing flange is not provided, nor is
it required for the L-39. I was concerned
because that part was missing, but it is
required only if the fan unit is used in a
nacelle.
Several motor options are available for the
HyperFlow fan unit. Slight trimming was
needed to fit the included Ammo power plant,
and the flange was premolded to act as a
guide. Three fan rotor shaft adapters (2mm,
2.3mm, and 3mm) are provided; the Albatros
motor has a 2mm shaft. The 2mm fan rotor
adapter would not initially slide onto the
motor shaft, so I assumed that it was too small
and went with the 2.3mm adapter.
When I had the model completed and
ready for motor testing, at full power the
Ammo—and the entire airframe—vibrated
severely. This cost me the impeller and a lot
of time trying to figure out what was wrong.
Great Planes’ customer support promptly
provided me with a replacement fan, since, at
the time, I thought the fan was out of balance.
In actuality, the shaft adapter was wobbling.
The problem was that the 2mm fan rotor
adapter was milled a bit too tight. After I
performed a slight deburring, it slowly started
to cooperate and slide onto the shaft.
The L-39’s airframe was easy to complete.
Futaba’s S3114 servos fit perfectly into the
aileron servo bays, and the servo cables fit
directly into the molded servo-lead channels.
The instructions recommended cyanoacrylate
to secure the servos; however, I used lowtemperature
hot glue, because it does not
permanently scar the servo case and makes
them easier to remove later.
I enjoyed using the included thumbscrew
pushrod connector; it makes adjusting the
aileron to the pushrod easy. Once the ailerons
are centered, a quick twist with the fingers
locks them in place. Finger-tight is not
enough, so use a screwdriver to completely
secure them.
When the ailerons are centered, glue the
aileron pushrod covers in place. Foamfriendly
cyanoacrylate worked fine until the
first landing, when both covers popped off.
I have found an excellent adhesive by
06sig3.QXD 4/22/09 12:12 PM Page 77
Devcon called Plastic Welder. It is a two-part
epoxy but welds the material together similar
to plastic model cement. Epoxy should work
fine as well.
Two grooves that are molded into the
fuselage match the flanges on the fan housing
that need to be glued into place. To ensure
proper placement, use a pen to mark the
grooves’ locations on the inside edge of the
fuselage. Use 30-minute epoxy for this step.
The motor wires are fed through a hole
at the bottom of the fuselage, through a
channel in the wing saddle, and then
passed through another hole back into the
forward fuselage. Ensure that all wires are
inserted correctly before gluing the fan
assembly in place.
Apply 30-minute epoxy to the wing
saddle, and glue the wing directly to the
fuselage. Make sure that the motor wires and
aileron-servo cables are properly seated within
the wire channels. The alignment keys molded
into the wing and saddle assure that the wing
is positioned correctly.
Set the airframe aside with a weight on top
of the fuselage until the adhesive cures.
The horizontal stabilizer and vertical
stabilizer are glued in place with epoxy.
Scrape away the paint from the mounting
area, to provide a stronger bond. The elevator
servo sits nicely in a foam servo tray that is
glued in place at the factory.
My Corona RD620 receiver from BP
Hobbies worked well with the Futaba servos.
Inside the fuselage is a guide tube for the
servo antenna, but getting the antenna through
is a tight squeeze. I used needle-nose pliers
and pushed the antenna through 1/4 inch at a
time, to keep it from bunching up. A small
amount of light oil will help it slide through.
Because of the L-39’s small size, setting it
up for flight is critical. Make sure that the CG
is correct and that the control throws are set
exactly to what the instruction manual
recommends.
My model required .5 ounce of weight in
the nose to obtain the correct CG. The low
rate on the elevator looks small, but little
elevator throw is needed for this short-coupled
aircraft.
Flying: The L-39 flies wonderfully but is
tricky. Having someone with hand-launching
experience nearby would be helpful.
I did not have an assistant for my test
flights, so I was on my own. I had never tried
an underhanded launch before and found the
method a bit unorthodox, but the instruction
manual recommended it so I figured I’d try
anyway.
The L-39 came out of my hand much
slower than I thought it would, and I was flatout
surprised that it kept flying. That’s a
testament to this design’s excellent slowspeed
performance. The times I was unable to
give it the toss it needed clearly demonstrated
the AeroCell’s durability.
I was more comfortable with the standard
overhead toss, gripping the fuselage directly
forward of the wing. Once it left my hand, the
L-39 needed to build speed before
establishing a climb. Launching with a correct
angle, of what I found to be approximately
10° nose up, worked well—especially for the
first five seconds, since there was not much
airflow over the stabilizer to make it very
effective.
Once out of the low-speed takeoff
envelope, the Albatros opened up and went to
town. At full power, it slid through the air at a
good clip. Speed was not blistering; I
estimated a good 60 mph, which is just fast
enough for a little jet such as this, since it
could quickly fly out of sight.
The recommended low rate settings are
plenty for flying the L-39. The aileron high
rate setting is great for spectacular axial rolls
at a rate of roughly two-and-a-half revolutions
per second. I recommend using the low
setting for the aileron at first, when
familiarizing yourself with the flight
performance.
Flying inverted required a considerable
amount of down-elevator, so switching to the
high rate for inverted flight made life easier.
After several flights, I kept the low rate at the
recommended 1/8 inch for up but increased the
downswing to 5/16 inch.
All aerobatics are possible for an airframe
with aileron and elevator. Loops require a bit
of downhill first, but the loops are large and
look great. Outside loops are also large and
scale-looking, but make sure to have plenty of
airspeed before attempting them.
For a small electric-ducted-fan jet with
such a short wing, the slow-speed
performance and stability astonished me, as
proven with my first attempted hand launch.
The L-39 will slow nicely for realistic landing
approaches. It’s not a glider, and power still
needs to be carried in on the approach.
Flying the Albatros to when the BEC shuts
down the motor is a bad idea; with no power,
the nose needs to drop to maintain a flyable
airspeed. I like to manage my flight time and
leave enough battery power in case I need to
make a go-around.
Average flight times with the ElectriFly
three-cell, 900 mAh battery are in the
neighborhood of seven minutes. With good
power management, 10-minute flight times
are possible.
At the low elevator setting, it took some
effort to coax the L-39 into a stall. A full stall
will result in a sudden nose drop and require
approximately 15 feet of altitude to recover
(with full power). Be cautious if flying slowly
at the high rates, especially in turns, because a
stall can occur suddenly.
From box to flight, my Albatros was an
enjoyable project. Quality is excellent, all
parts fit well, and I had no trouble building it,
aside from my goof with the motor adapter.
Despite being a small scale jet, it is well
behaved. If you can handle an aileron/elevator
aircraft and want to bring some jet action to
your field, try the ElectriFly L-39. I doubt that
you will be disappointed with the quality,
looks, performance, or durability. MA
Peter C. Oesterwinter
[email protected]
Manufacturer/Distributor:
ElectriFly/Great Planes
Box 9021
Champaign IL 61826
(217) 398-3630
www.electrifly.com
Sources:
Futaba
(217) 398-3630
www.futaba-rc.com
BP Hobbies
(732) 287-3933
www.bphobbies.com
Devcon
(800) 933-8266
www.devcon.com
Other Published Reviews:
Backyard Flyer: September 2008
RC Sport Flyer: October 2008
R/C Report: October 2008
Fly RC: November 2008
Edition: Model Aviation - 2009/06
Page Numbers: 75,76,77,78
PETER C. OESTERWINTER
Plane Talk: Great Planes L-39 Albatros Jet EDF ARF
Above: Even though it’s fragile, the included
stand looks good and is a great way to display
the L-39 at home or at the office.
A dynamite package
for the park or field
The instructions make it clear not to use the drop tanks and missiles for flight—
but they looked so good, and magnets held them tight. The Albatros knew they
were there.
AERO VODOCHODY Corporation in
Czechoslovakia designed and manufactured
the full-scale L-39. Even though it was
invented to be a trainer, the Albatros has also
seen duty as a light attack aircraft.
When looking at this striking jet, it’s hard
to believe that its design dates back to the
1960s, with its maiden flight taking place on
November 4, 1968. The design is so sound
that it evolved into the L-59 Super Albatros,
which is still in production.
With more than 2,800 still in service, the
Albatros has become available to private
buyers who are looking for a unique yet
pricey thrill ride. You can get one for
approximately $300,000. With the cost of
fuel these days, I hate to imagine how much it
costs to operate that thirsty little jet.
In its ElectriFly series, Great Planes has
successfully captured all of this awesome
aircraft’s beauty and scaled it down into a
well-engineered model. For a street price of
$99, you can pick up one of these little
beauties instead of the full-scale version and
save $299,901.
At a length of 31 inches, the ElectriFly L-
39 is 1:15 scale. It is molded from AeroCell: a
closed-cell EPP-foam material that is
lightweight, durable, and has a smooth finish
(compared to older foam materials). It is ideal
for the nice factory-applied scale paint
scheme.
Thanks to the low parts count, the
Albatros’s assembly process from box to air is
quick. My production sample took less than
three hours to get ready for flight.
Contents: The box containing the ElectriFly
L-39 Albatros was well decorated and well
presented. I spent quite a bit of time turning
the box in my hands, reading all of the
information printed on it. There were many
June 2009 75
06sig3.QXD 4/22/09 12:56 PM Page 75
76 MODEL AVIATION
Pluses and Minuses
+
• Excellent quality and parts fit.
• Quick assembly time.
• Accurate scale outline.
• Stunning performance in all flight envelopes.
• Attractive home-display stand is included.
-
• Paint adheres poorly to AeroCell foam and will come
off with normal use.
Specifications and Equipment Used
Type: Electric ducted fan sport-scale
Wingspan: 25 inches
Length: 31 inches
Weight: 17.5-18.5 ounces
Weight as flown: 17.9 ounces
Wing loading: 17.9-18.9 ounces/square foot
Radio required: Three channels (aileron, elevator,
throttle)
Motor: Ammo 20-40-3500
Radio: Futaba T6XA
Receiver: Corona RD620
Servos: Futaba S3114
ESC: ElectriFly Silver Series 25A
Battery: ElectriFly Power Series 3S 910 mAh
The model comes out of the box with parts individually bagged, to
prevent chafing of the clean paint finish. The HyperFlow fan unit and
Ammo motor are included.
To accommodate the 20mm Ammo brushless power plant, a
small amount of material needs to be trimmed from the mount.
The power system requires no soldering.
Static photos by the author Flight photos by Denise Donnolly and Tim Mangee
Two marks where flanges are located in the fuselage make it
easier to seat the HyperFlow fan in the correct location. Magnet
closures are used throughout.
Make sure that the motor leads are in their channels before
permanently securing the wing in place with epoxy. Scuff the parts
first.
06sig3.QXD 4/22/09 12:09 PM Page 76
June 2009 77
Below: The ARF is molded from EPP-style foam. The latest version of the Albatros—the
Rx-R—has a detailed cockpit and is made from AeroCell foam.
External dummy fuel tanks serve as landing skids. Oversized
inlets ensure that the HyperFlow fan breathes well. A 900 mAh
3S pack can offer more than eight minutes of flight time.
The author’s son, Josh, demonstrates his dad’s preferred launch
grip and stance. A fast, level toss, with the EDF throttle fully
open, will get the L-39 flying.
photos and diagrams and a great deal of
technical information to pour over.
Once I opened the box, I was delighted
with what was inside. All parts were
individually bagged and well packed. There
were four major airframe components:
fuselage, one-piece wing, stabilizer/elevator,
and vertical stabilizer.
Because AeroCell is naturally flexible,
the typical assembly step of hinging was not
required; all flying surfaces were molded in
one piece with the control surfaces attached.
The only thing I would do to them at this
point would be to flex the control surfaces to
free them a bit.
The Ammo brushless motor and
HyperFlow ducted fan combination was
included with its own instruction manual.
Hardware was also supplied, and it had
some good features I will explain later.
As I mentioned earlier, the paint was
applied superbly, and the panel lines were
not oversized—a feature I have seen on
other foam models. Simulated drop tanks,
tip tanks, and missiles were included and
attached by powerful rare earth magnets.
The tip tanks could stay, but the missiles
and drop tanks needed to be removed for
flight. The canopy was also held securely
in place by rare earth magnets.
The included display stand looked elegant
and was great for showing the L-39 at home,
but is a bit fragile, so handle with care.
Assembly: Locate the manual showing how
to assemble the HyperFlow fan unit. The steps
are clear and easy to follow.
Do not panic when examining all the parts;
the front housing flange is not provided, nor is
it required for the L-39. I was concerned
because that part was missing, but it is
required only if the fan unit is used in a
nacelle.
Several motor options are available for the
HyperFlow fan unit. Slight trimming was
needed to fit the included Ammo power plant,
and the flange was premolded to act as a
guide. Three fan rotor shaft adapters (2mm,
2.3mm, and 3mm) are provided; the Albatros
motor has a 2mm shaft. The 2mm fan rotor
adapter would not initially slide onto the
motor shaft, so I assumed that it was too small
and went with the 2.3mm adapter.
When I had the model completed and
ready for motor testing, at full power the
Ammo—and the entire airframe—vibrated
severely. This cost me the impeller and a lot
of time trying to figure out what was wrong.
Great Planes’ customer support promptly
provided me with a replacement fan, since, at
the time, I thought the fan was out of balance.
In actuality, the shaft adapter was wobbling.
The problem was that the 2mm fan rotor
adapter was milled a bit too tight. After I
performed a slight deburring, it slowly started
to cooperate and slide onto the shaft.
The L-39’s airframe was easy to complete.
Futaba’s S3114 servos fit perfectly into the
aileron servo bays, and the servo cables fit
directly into the molded servo-lead channels.
The instructions recommended cyanoacrylate
to secure the servos; however, I used lowtemperature
hot glue, because it does not
permanently scar the servo case and makes
them easier to remove later.
I enjoyed using the included thumbscrew
pushrod connector; it makes adjusting the
aileron to the pushrod easy. Once the ailerons
are centered, a quick twist with the fingers
locks them in place. Finger-tight is not
enough, so use a screwdriver to completely
secure them.
When the ailerons are centered, glue the
aileron pushrod covers in place. Foamfriendly
cyanoacrylate worked fine until the
first landing, when both covers popped off.
I have found an excellent adhesive by
06sig3.QXD 4/22/09 12:12 PM Page 77
Devcon called Plastic Welder. It is a two-part
epoxy but welds the material together similar
to plastic model cement. Epoxy should work
fine as well.
Two grooves that are molded into the
fuselage match the flanges on the fan housing
that need to be glued into place. To ensure
proper placement, use a pen to mark the
grooves’ locations on the inside edge of the
fuselage. Use 30-minute epoxy for this step.
The motor wires are fed through a hole
at the bottom of the fuselage, through a
channel in the wing saddle, and then
passed through another hole back into the
forward fuselage. Ensure that all wires are
inserted correctly before gluing the fan
assembly in place.
Apply 30-minute epoxy to the wing
saddle, and glue the wing directly to the
fuselage. Make sure that the motor wires and
aileron-servo cables are properly seated within
the wire channels. The alignment keys molded
into the wing and saddle assure that the wing
is positioned correctly.
Set the airframe aside with a weight on top
of the fuselage until the adhesive cures.
The horizontal stabilizer and vertical
stabilizer are glued in place with epoxy.
Scrape away the paint from the mounting
area, to provide a stronger bond. The elevator
servo sits nicely in a foam servo tray that is
glued in place at the factory.
My Corona RD620 receiver from BP
Hobbies worked well with the Futaba servos.
Inside the fuselage is a guide tube for the
servo antenna, but getting the antenna through
is a tight squeeze. I used needle-nose pliers
and pushed the antenna through 1/4 inch at a
time, to keep it from bunching up. A small
amount of light oil will help it slide through.
Because of the L-39’s small size, setting it
up for flight is critical. Make sure that the CG
is correct and that the control throws are set
exactly to what the instruction manual
recommends.
My model required .5 ounce of weight in
the nose to obtain the correct CG. The low
rate on the elevator looks small, but little
elevator throw is needed for this short-coupled
aircraft.
Flying: The L-39 flies wonderfully but is
tricky. Having someone with hand-launching
experience nearby would be helpful.
I did not have an assistant for my test
flights, so I was on my own. I had never tried
an underhanded launch before and found the
method a bit unorthodox, but the instruction
manual recommended it so I figured I’d try
anyway.
The L-39 came out of my hand much
slower than I thought it would, and I was flatout
surprised that it kept flying. That’s a
testament to this design’s excellent slowspeed
performance. The times I was unable to
give it the toss it needed clearly demonstrated
the AeroCell’s durability.
I was more comfortable with the standard
overhead toss, gripping the fuselage directly
forward of the wing. Once it left my hand, the
L-39 needed to build speed before
establishing a climb. Launching with a correct
angle, of what I found to be approximately
10° nose up, worked well—especially for the
first five seconds, since there was not much
airflow over the stabilizer to make it very
effective.
Once out of the low-speed takeoff
envelope, the Albatros opened up and went to
town. At full power, it slid through the air at a
good clip. Speed was not blistering; I
estimated a good 60 mph, which is just fast
enough for a little jet such as this, since it
could quickly fly out of sight.
The recommended low rate settings are
plenty for flying the L-39. The aileron high
rate setting is great for spectacular axial rolls
at a rate of roughly two-and-a-half revolutions
per second. I recommend using the low
setting for the aileron at first, when
familiarizing yourself with the flight
performance.
Flying inverted required a considerable
amount of down-elevator, so switching to the
high rate for inverted flight made life easier.
After several flights, I kept the low rate at the
recommended 1/8 inch for up but increased the
downswing to 5/16 inch.
All aerobatics are possible for an airframe
with aileron and elevator. Loops require a bit
of downhill first, but the loops are large and
look great. Outside loops are also large and
scale-looking, but make sure to have plenty of
airspeed before attempting them.
For a small electric-ducted-fan jet with
such a short wing, the slow-speed
performance and stability astonished me, as
proven with my first attempted hand launch.
The L-39 will slow nicely for realistic landing
approaches. It’s not a glider, and power still
needs to be carried in on the approach.
Flying the Albatros to when the BEC shuts
down the motor is a bad idea; with no power,
the nose needs to drop to maintain a flyable
airspeed. I like to manage my flight time and
leave enough battery power in case I need to
make a go-around.
Average flight times with the ElectriFly
three-cell, 900 mAh battery are in the
neighborhood of seven minutes. With good
power management, 10-minute flight times
are possible.
At the low elevator setting, it took some
effort to coax the L-39 into a stall. A full stall
will result in a sudden nose drop and require
approximately 15 feet of altitude to recover
(with full power). Be cautious if flying slowly
at the high rates, especially in turns, because a
stall can occur suddenly.
From box to flight, my Albatros was an
enjoyable project. Quality is excellent, all
parts fit well, and I had no trouble building it,
aside from my goof with the motor adapter.
Despite being a small scale jet, it is well
behaved. If you can handle an aileron/elevator
aircraft and want to bring some jet action to
your field, try the ElectriFly L-39. I doubt that
you will be disappointed with the quality,
looks, performance, or durability. MA
Peter C. Oesterwinter
[email protected]
Manufacturer/Distributor:
ElectriFly/Great Planes
Box 9021
Champaign IL 61826
(217) 398-3630
www.electrifly.com
Sources:
Futaba
(217) 398-3630
www.futaba-rc.com
BP Hobbies
(732) 287-3933
www.bphobbies.com
Devcon
(800) 933-8266
www.devcon.com
Other Published Reviews:
Backyard Flyer: September 2008
RC Sport Flyer: October 2008
R/C Report: October 2008
Fly RC: November 2008
Edition: Model Aviation - 2009/06
Page Numbers: 75,76,77,78
PETER C. OESTERWINTER
Plane Talk: Great Planes L-39 Albatros Jet EDF ARF
Above: Even though it’s fragile, the included
stand looks good and is a great way to display
the L-39 at home or at the office.
A dynamite package
for the park or field
The instructions make it clear not to use the drop tanks and missiles for flight—
but they looked so good, and magnets held them tight. The Albatros knew they
were there.
AERO VODOCHODY Corporation in
Czechoslovakia designed and manufactured
the full-scale L-39. Even though it was
invented to be a trainer, the Albatros has also
seen duty as a light attack aircraft.
When looking at this striking jet, it’s hard
to believe that its design dates back to the
1960s, with its maiden flight taking place on
November 4, 1968. The design is so sound
that it evolved into the L-59 Super Albatros,
which is still in production.
With more than 2,800 still in service, the
Albatros has become available to private
buyers who are looking for a unique yet
pricey thrill ride. You can get one for
approximately $300,000. With the cost of
fuel these days, I hate to imagine how much it
costs to operate that thirsty little jet.
In its ElectriFly series, Great Planes has
successfully captured all of this awesome
aircraft’s beauty and scaled it down into a
well-engineered model. For a street price of
$99, you can pick up one of these little
beauties instead of the full-scale version and
save $299,901.
At a length of 31 inches, the ElectriFly L-
39 is 1:15 scale. It is molded from AeroCell: a
closed-cell EPP-foam material that is
lightweight, durable, and has a smooth finish
(compared to older foam materials). It is ideal
for the nice factory-applied scale paint
scheme.
Thanks to the low parts count, the
Albatros’s assembly process from box to air is
quick. My production sample took less than
three hours to get ready for flight.
Contents: The box containing the ElectriFly
L-39 Albatros was well decorated and well
presented. I spent quite a bit of time turning
the box in my hands, reading all of the
information printed on it. There were many
June 2009 75
06sig3.QXD 4/22/09 12:56 PM Page 75
76 MODEL AVIATION
Pluses and Minuses
+
• Excellent quality and parts fit.
• Quick assembly time.
• Accurate scale outline.
• Stunning performance in all flight envelopes.
• Attractive home-display stand is included.
-
• Paint adheres poorly to AeroCell foam and will come
off with normal use.
Specifications and Equipment Used
Type: Electric ducted fan sport-scale
Wingspan: 25 inches
Length: 31 inches
Weight: 17.5-18.5 ounces
Weight as flown: 17.9 ounces
Wing loading: 17.9-18.9 ounces/square foot
Radio required: Three channels (aileron, elevator,
throttle)
Motor: Ammo 20-40-3500
Radio: Futaba T6XA
Receiver: Corona RD620
Servos: Futaba S3114
ESC: ElectriFly Silver Series 25A
Battery: ElectriFly Power Series 3S 910 mAh
The model comes out of the box with parts individually bagged, to
prevent chafing of the clean paint finish. The HyperFlow fan unit and
Ammo motor are included.
To accommodate the 20mm Ammo brushless power plant, a
small amount of material needs to be trimmed from the mount.
The power system requires no soldering.
Static photos by the author Flight photos by Denise Donnolly and Tim Mangee
Two marks where flanges are located in the fuselage make it
easier to seat the HyperFlow fan in the correct location. Magnet
closures are used throughout.
Make sure that the motor leads are in their channels before
permanently securing the wing in place with epoxy. Scuff the parts
first.
06sig3.QXD 4/22/09 12:09 PM Page 76
June 2009 77
Below: The ARF is molded from EPP-style foam. The latest version of the Albatros—the
Rx-R—has a detailed cockpit and is made from AeroCell foam.
External dummy fuel tanks serve as landing skids. Oversized
inlets ensure that the HyperFlow fan breathes well. A 900 mAh
3S pack can offer more than eight minutes of flight time.
The author’s son, Josh, demonstrates his dad’s preferred launch
grip and stance. A fast, level toss, with the EDF throttle fully
open, will get the L-39 flying.
photos and diagrams and a great deal of
technical information to pour over.
Once I opened the box, I was delighted
with what was inside. All parts were
individually bagged and well packed. There
were four major airframe components:
fuselage, one-piece wing, stabilizer/elevator,
and vertical stabilizer.
Because AeroCell is naturally flexible,
the typical assembly step of hinging was not
required; all flying surfaces were molded in
one piece with the control surfaces attached.
The only thing I would do to them at this
point would be to flex the control surfaces to
free them a bit.
The Ammo brushless motor and
HyperFlow ducted fan combination was
included with its own instruction manual.
Hardware was also supplied, and it had
some good features I will explain later.
As I mentioned earlier, the paint was
applied superbly, and the panel lines were
not oversized—a feature I have seen on
other foam models. Simulated drop tanks,
tip tanks, and missiles were included and
attached by powerful rare earth magnets.
The tip tanks could stay, but the missiles
and drop tanks needed to be removed for
flight. The canopy was also held securely
in place by rare earth magnets.
The included display stand looked elegant
and was great for showing the L-39 at home,
but is a bit fragile, so handle with care.
Assembly: Locate the manual showing how
to assemble the HyperFlow fan unit. The steps
are clear and easy to follow.
Do not panic when examining all the parts;
the front housing flange is not provided, nor is
it required for the L-39. I was concerned
because that part was missing, but it is
required only if the fan unit is used in a
nacelle.
Several motor options are available for the
HyperFlow fan unit. Slight trimming was
needed to fit the included Ammo power plant,
and the flange was premolded to act as a
guide. Three fan rotor shaft adapters (2mm,
2.3mm, and 3mm) are provided; the Albatros
motor has a 2mm shaft. The 2mm fan rotor
adapter would not initially slide onto the
motor shaft, so I assumed that it was too small
and went with the 2.3mm adapter.
When I had the model completed and
ready for motor testing, at full power the
Ammo—and the entire airframe—vibrated
severely. This cost me the impeller and a lot
of time trying to figure out what was wrong.
Great Planes’ customer support promptly
provided me with a replacement fan, since, at
the time, I thought the fan was out of balance.
In actuality, the shaft adapter was wobbling.
The problem was that the 2mm fan rotor
adapter was milled a bit too tight. After I
performed a slight deburring, it slowly started
to cooperate and slide onto the shaft.
The L-39’s airframe was easy to complete.
Futaba’s S3114 servos fit perfectly into the
aileron servo bays, and the servo cables fit
directly into the molded servo-lead channels.
The instructions recommended cyanoacrylate
to secure the servos; however, I used lowtemperature
hot glue, because it does not
permanently scar the servo case and makes
them easier to remove later.
I enjoyed using the included thumbscrew
pushrod connector; it makes adjusting the
aileron to the pushrod easy. Once the ailerons
are centered, a quick twist with the fingers
locks them in place. Finger-tight is not
enough, so use a screwdriver to completely
secure them.
When the ailerons are centered, glue the
aileron pushrod covers in place. Foamfriendly
cyanoacrylate worked fine until the
first landing, when both covers popped off.
I have found an excellent adhesive by
06sig3.QXD 4/22/09 12:12 PM Page 77
Devcon called Plastic Welder. It is a two-part
epoxy but welds the material together similar
to plastic model cement. Epoxy should work
fine as well.
Two grooves that are molded into the
fuselage match the flanges on the fan housing
that need to be glued into place. To ensure
proper placement, use a pen to mark the
grooves’ locations on the inside edge of the
fuselage. Use 30-minute epoxy for this step.
The motor wires are fed through a hole
at the bottom of the fuselage, through a
channel in the wing saddle, and then
passed through another hole back into the
forward fuselage. Ensure that all wires are
inserted correctly before gluing the fan
assembly in place.
Apply 30-minute epoxy to the wing
saddle, and glue the wing directly to the
fuselage. Make sure that the motor wires and
aileron-servo cables are properly seated within
the wire channels. The alignment keys molded
into the wing and saddle assure that the wing
is positioned correctly.
Set the airframe aside with a weight on top
of the fuselage until the adhesive cures.
The horizontal stabilizer and vertical
stabilizer are glued in place with epoxy.
Scrape away the paint from the mounting
area, to provide a stronger bond. The elevator
servo sits nicely in a foam servo tray that is
glued in place at the factory.
My Corona RD620 receiver from BP
Hobbies worked well with the Futaba servos.
Inside the fuselage is a guide tube for the
servo antenna, but getting the antenna through
is a tight squeeze. I used needle-nose pliers
and pushed the antenna through 1/4 inch at a
time, to keep it from bunching up. A small
amount of light oil will help it slide through.
Because of the L-39’s small size, setting it
up for flight is critical. Make sure that the CG
is correct and that the control throws are set
exactly to what the instruction manual
recommends.
My model required .5 ounce of weight in
the nose to obtain the correct CG. The low
rate on the elevator looks small, but little
elevator throw is needed for this short-coupled
aircraft.
Flying: The L-39 flies wonderfully but is
tricky. Having someone with hand-launching
experience nearby would be helpful.
I did not have an assistant for my test
flights, so I was on my own. I had never tried
an underhanded launch before and found the
method a bit unorthodox, but the instruction
manual recommended it so I figured I’d try
anyway.
The L-39 came out of my hand much
slower than I thought it would, and I was flatout
surprised that it kept flying. That’s a
testament to this design’s excellent slowspeed
performance. The times I was unable to
give it the toss it needed clearly demonstrated
the AeroCell’s durability.
I was more comfortable with the standard
overhead toss, gripping the fuselage directly
forward of the wing. Once it left my hand, the
L-39 needed to build speed before
establishing a climb. Launching with a correct
angle, of what I found to be approximately
10° nose up, worked well—especially for the
first five seconds, since there was not much
airflow over the stabilizer to make it very
effective.
Once out of the low-speed takeoff
envelope, the Albatros opened up and went to
town. At full power, it slid through the air at a
good clip. Speed was not blistering; I
estimated a good 60 mph, which is just fast
enough for a little jet such as this, since it
could quickly fly out of sight.
The recommended low rate settings are
plenty for flying the L-39. The aileron high
rate setting is great for spectacular axial rolls
at a rate of roughly two-and-a-half revolutions
per second. I recommend using the low
setting for the aileron at first, when
familiarizing yourself with the flight
performance.
Flying inverted required a considerable
amount of down-elevator, so switching to the
high rate for inverted flight made life easier.
After several flights, I kept the low rate at the
recommended 1/8 inch for up but increased the
downswing to 5/16 inch.
All aerobatics are possible for an airframe
with aileron and elevator. Loops require a bit
of downhill first, but the loops are large and
look great. Outside loops are also large and
scale-looking, but make sure to have plenty of
airspeed before attempting them.
For a small electric-ducted-fan jet with
such a short wing, the slow-speed
performance and stability astonished me, as
proven with my first attempted hand launch.
The L-39 will slow nicely for realistic landing
approaches. It’s not a glider, and power still
needs to be carried in on the approach.
Flying the Albatros to when the BEC shuts
down the motor is a bad idea; with no power,
the nose needs to drop to maintain a flyable
airspeed. I like to manage my flight time and
leave enough battery power in case I need to
make a go-around.
Average flight times with the ElectriFly
three-cell, 900 mAh battery are in the
neighborhood of seven minutes. With good
power management, 10-minute flight times
are possible.
At the low elevator setting, it took some
effort to coax the L-39 into a stall. A full stall
will result in a sudden nose drop and require
approximately 15 feet of altitude to recover
(with full power). Be cautious if flying slowly
at the high rates, especially in turns, because a
stall can occur suddenly.
From box to flight, my Albatros was an
enjoyable project. Quality is excellent, all
parts fit well, and I had no trouble building it,
aside from my goof with the motor adapter.
Despite being a small scale jet, it is well
behaved. If you can handle an aileron/elevator
aircraft and want to bring some jet action to
your field, try the ElectriFly L-39. I doubt that
you will be disappointed with the quality,
looks, performance, or durability. MA
Peter C. Oesterwinter
[email protected]
Manufacturer/Distributor:
ElectriFly/Great Planes
Box 9021
Champaign IL 61826
(217) 398-3630
www.electrifly.com
Sources:
Futaba
(217) 398-3630
www.futaba-rc.com
BP Hobbies
(732) 287-3933
www.bphobbies.com
Devcon
(800) 933-8266
www.devcon.com
Other Published Reviews:
Backyard Flyer: September 2008
RC Sport Flyer: October 2008
R/C Report: October 2008
Fly RC: November 2008