Review: Modellbau USA F-86D Sabre - 2012/03

www.ModelAviation.com March 2012 Model Aviation 65
The F-86 is one of the best known of the jet fi ghters and a participant in MiG
Alley during the Korean War. The aircraft starred in many movies and began
life as the straight-wing North American Aviation FJ-1 Fury. When that
version did not meet design criteria, among other changes, a 35° swept wing was
substituted, and in 1947 the YF-86 took to the skies.
With the fear of hordes of Soviet bombers attacking the US, work on a bomber
interceptor, the F-95A, began. The aircraft was renamed the F-86D and was wider
and longer, with a larger engine and a clamshell canopy. It was the fi rst Air Force
night fi ghter with a single engine and a single pilot.
The Sabre was only slightly similar to the other variants. It had a retractable tray
in the belly that held 24 2.75-inch Mighty Mouse Mk 4 Rockets instead of guns. It
was believed that the rockets would be more effective against a bomber formation,
especially at night.
Another variety was marketed as a NATO fi ghter. This model, known as the
F-86K, had the rocket tray replaced with four 20mm cannons. It was painted in a
number of color and camoufl age schemes.
Having had several versions of the venerable F-86, both electric-powered ductedfan
(EDF) models and glow-powered ducted-fan aircraft, I was thrilled to review this
release from ModellbauUSA.
I believe only two models of the F-86D have been produced—one many years ago
by Byron, and a propeller-jet version imported by Nitro Models. This version was
designed for turbine power, specifi cally the JetCat P60, with the focus on weight
management and simplicity.
Converting to EDF is as simple as replacing the stainless steel turbine tailpipe
with a Mylar tube and adding intake ducting. Adequate strength is needed to
accommodate the more powerful, heavier KingTech K-80 (which I used in this
review) and this has been designed in.
Is this a totally Scale, “let’s go to the Jet World Masters” aircraft? No. It is a Sport
Scale version of the most numerous variant of the Sabre. Scale fi delity in landing
gear placement is sacrifi ced for a wider and more stable confi guration, along with
slightly more wing area.
The model presents well in the air. This was taken shortly after liftoff. Charles Scarborough photo.
A turbine that’s
friendly to fi rsttime
jet pilots
Greg Moore
REVIEW MODELLBAU USA F-86D DOG SABRE jetfl [email protected]
Photos by the author unless noted66 Model Aviation March 2012 www.ModelAviation.com
If you are a Scale junkie, this airplane
is not for you; however, if you want
an attractive replica of a great-fl ying
airplane with a wide speed range and
fantastic ground handling added, this
might be for you.
The model is roughly the same
price as many of the larger ARFs in
the current Tower Hobbies catalog.
Modellbau has decided to sell the
aircraft, which is designed around the
15- to 20-pound thrust engines, in a
transportable size at a reasonable price.
Unpacking
The model is well-packed, but the
one I received suffered mild cracking
in the tail during shipping. It was easily
repaired, and is a testimony to the
correct strength and number of fi berglass
layers used in the layup.
The box includes a nicely fabricated
and painted fi berglass fuselage, sheeted
built-up wings, and tail feathers with
iron-on covering and stick-on decals.
Spring Air’s new, red, heavy-duty landing
gear is preinstalled. The package also
includes a prepainted, modern jet pilot
fi gure, lightweight, dual-walled tailpipe,
custom fi berglass fuel tanks, and all the
linkage hardware needed to assemble
the airplane.
You will need to purchase struts,
wheels, and brakes (I used the Spring
Air/Modellbau combination package),
as well as engine and radio components.
I used the KingTech K-80f, kero-start
engine, which I will discuss later.
Building the Dog Sabre
Because the instructions are
straightforward and available online
as a PDF, I will not give a step-by-step
review. Instead, I will assess items that
need clarifi cation, are interesting, or have
changed.
The fi rst topic is hinging all of the
control surfaces. You should be able
to open and check the contents of the
box, unpack everything, seal and shrink
the wrinkles in the covering, and hinge
your surfaces in one evening, or part of
a weekend day. The precut slots are that
well done.
Make sure you open/bevel the hinge
slots so the hinges are slightly recessed
to minimize the gaps. Lubricate your
hinge with some melted Vaseline, and
use a good, slow-setting epoxy such as
Hysol 9462 or E-20HP (available from
McMaster-Carr online, or your local
Fastenal store).
The only item of note in this part of
the assembly concerns the fl aps. The
SPECIFICATIONS
Type Sport Scale turbine jet
Skill level Intermediate builder;
intermediate pilot
Wingspan 60 inches
Wing area 895 square inches
Length 68 inches
Flying weight 15 pounds
engine 12- to 18-pound thrust turbine (or
large electric-powered ducted fan).
Recommended JetCat P60 or KingTech K-80
engines
Radio Nine-channel minimum with 11
servos
Construction Composite fuselage with builtup
sheeted wings and tail
Covering/fi nish Painted fi berglass fuselage,
iron-on covering on sheeted
parts
Street price $760
TEST-MODEL DETAILS
Engine KingTech K-80F
Radio system Futaba 12Z transmitter, Futaba
FASST 6014HS receiver, Futaba
GY 190 gyro
Ready-to-fl y 16 pounds, 2 ounces
weight
Flight duration 9 to 10 minutes
KINGTECH K-80F SPECIFICATIONS
Diameter 3¾ inches (95.25mm)
Length 10 inches (254mm) including
starter
Weight 2 pounds, 14 ounces (1304 g)
including starter
Maximum rpm 145,000
Thrust 19 pounds at 70° F
Idle 45,000 rpm
Exhaust 1202° F (650° C) maximum
temperature
Fuel 8.46 ounces per minute
consumption (239 grams per minute)
Maintenance 25 hours
cycle
Oil 5% Turbine oil
PLUSES
• Uses a wide range and selection of engine sizes.
• Gentle, predictable handling and performs well.
• Could be used as a fi rst jet.
• All included hardware is high quality.
MINUSES
• Landing gear too long for Scale appearance.
• Canopy could be constructed from clearer/
thicker material.
AT A GLANCE....
REVIEW
Everything needed to operate the engine is included with the exception of a battery pack.
Quality components are used throughout.www.ModelAviation.com March 2012 Model Aviation 67
incorrectly plug in the wires.
The rudder and elevator servos are
mounted inside the fin and stabilizers.
The rudder servo mounting is
straightforward. Add two hardwood
blocks to the hatch to fit the suggested
Hitec 5245MG servo, allowing the
control arm to center in the precut slot,
and then mount the hatch. The elevator
servos required more thought because
the stabilizers are so thin.
Modellbau recommends a thin-wing
servo with metal gears and at least 65
ounce-inches of torque for the elevators.
I used the JR Radios digital 378 thinwing
servo that meets the criteria.
It seemed to be designed to mount
against a hatch or surface, so I decided to
mount the servo to the hatch with four
4-40 machine screws through the four
mounting lugs. The rear set went all the
way through the double lugs, while the
front set had the lock, washer, and nut
between the lugs.
I cut a piece of ¼-inch aircraft-grade
plywood to fit snugly between the lugs
and fit against the front and rear spars,
trimmed them to the correct thickness
to allow the hatch to fit flush with the
bottom skin, and then epoxied them
into place using the hatch/servo to
position things.
Spring Air’s Red Jet series of
retracts are included in the kit
and feature larger cylinders and
springs to handle higher speeds.
The optional trailing link struts
look nice and function well.
precut and beveled flaps are hinged in
the middle of the surface, which allows
only 35mm of flap deflection. This is
perfect for a small engine such as the
JetCat P60, but can’t generate the 45mm
of deflection needed for a larger engine.
If you plan to use a KingTech K-80,
JetCat P70, Wren 70, or Super Sport,
the bevel in the flap should be filled
with a ¼-inch balsa strip and then
hinged at the bottom. My model could
have benefitted from the full 45mm of
flap deflection.
Keeping things as simple as possible,
Modellbau designed the aircraft to have
the servos outside of the wing; just
harden the holes with some thin CA and
screw them in.
The recommended servo for both
ailerons and flaps is the Hitec 645MG,
but since I still have 12 new 605s, I used
these. Control horn placement is as easy
as cutting a slot, setting the horn with
Hysol E20HP, and letting it cure.
I like to protect my wiring connections
from myself. With two servo leads to
the wings, and because I have managed
to connect the wrong pair in the past,
I eliminated that problem by using a
six-pin Multiplex connector. With each
extension wired to it, it’s impossible to
The well-protected contents include everything but glue, electronics, and an engine.68 Model Aviation March 2012 www.ModelAviation.com
I would have liked to move the engine
farther forward to help with balancing,
but the 1/2-inch gap I needed between
the engine and pipe dictated the fi nal
engine position. It is a good idea to fi t the
pipe-support mount and secure it with
epoxy mixed with fi berglass millings.
My next step was fi guring out where
I could neatly place everything that
needed to go into the fuselage—as
far forward as possible for balancing
purposes. I made a 1/8-inch plywood
REVIEW
Servo wires running to the
elevators and rudder pass close
to the tail pipe, so cover them
with aluminum heating-duct
tape or a heat shield.
The author slightly
scalloped the exit
opening on the bottom
to allow the stainless
steel pipe to exit the
fuselage.
When the engine mounting rails are correctly trimmed, the engine fi ts
evenly within them.
The elevator/servo openings are shallow, requiring a thin-wing servo and
creativity in mounting. Greg fabricated 1/4-inch plywood plates that fi t
snugly within the servo mounting lugs.
ended up with a scallop to allow the
pipe to exit.
Before installing the pipe supports, run
the servo wires to the rear and protect
them with aluminum tape or heat shield.
With the servo leads secure, the engine
can be fi tted through the bottom hatch
and onto the rails. The rails are narrow
enough for a P60 without needing to
add material. With the wider K-80, all I
had to do was remove a small amount of
wood to set the engine in place.
When dry, the hatch was screwed
to the ¼-inch plywood mounts with
servo screws from Micro Fasteners,
and the control horn was placed as
described earlier.
Now is a good time to open the rear
of the fuselage enough to allow the tail
pipe to exit. The hole is only a rough
opening, allowing those using their
pipe of choice to get the correct fi t. I
found that 90% of the trimming
I needed was on the bottom, andplate that screwed into some ¼-inch
plywood blocks with servo screws on
the right side, and used the already
installed mounting plates to mount
the Spring Air retract valve and dual
switch. Designed for large, gas-powered
engines, the switch is robust, has a small
mounting footprint, and snaps into on or
off position, as well as charge leads.
Likewise, I mounted the ECU to a
plywood plate epoxied to the bottom
of the fuselage. It’s easy to connect to
the ground-support unit and I like to
monitor the start information.
I use dual receiver packs with separate
switches into separate ports in the
receiver on my jets, so space was needed
for a pair of Hobbico LiFe 6.6-volt, 2100
mAh packs and the provided 9.9-volt
A123-LiFe pump pack in a secure spot
that was as far forward as possible.
The receiver packs can be mounted
with Velcro alongside the nose gear rails,
and the pump pack can be mounted
along with the retract air tank above the
inlet in the radome. It’s diffi cult to place
these heavier objects any farther forward.
This large space becomes small
quickly, and it gets even smaller when
you assemble the fuel tanks. I had to
open the existing hole in the bulkhead
to allow the fuel tank cap and lines to
come through smoothly. I trimmed
roughly 3/8 inch from the fl ange on top
of the fuselage to allow the tanks to
enter easily.
A thin piece of plywood was needed
beneath the inside edge of the tanks
so they would fi t fl ush with the sides
of the fuselage. Goop, PFM, or other
silicone adhesive between the tanks
and sides will keep the tanks in place.
With two tubular spars running through
the fuselage, it is important that the
servo leads and fuel and air lines are
secured to the fuselage with keepers or
attachments.
The Spring Air struts were mounted
into their retract units, given some
toe-in, then slowly retracted to avoid
smashing into the top skin. I had to
remove some of the wing rib, and shim
the landing gear to prevent it from
wedging against the top of the wing.
When I was happy with the fi t, I
made wheel well inserts to keep large
masses of air out of the wing. A hint Ifound online suggested I use an empty
cereal box, trimmed to shape, and
use my favorite Bob Smith Industries
medium CA to secure it in place. A coat
of thinned epoxy gave it fuel and water
protection and I was done.
To secure the wings to the fuselage,
carefully measure then drill a hole for
a ¼-20 bolt. If you have small hands,
a thumbscrew could be used to attachthe wing. I had to insert a carriage bolt
that I cut the head off of into the
blind nut in the wing and secure it
with blue threadlocker. This bolt goes
into the fuselage and through a ¼-inch
wheel collar that is secured within a
plywood block and epoxied to the side
of the fuselage.
An 8-32 bolt is substituted for the
setscrew and a fl at slot is cut into the70 Model Aviation March 2012 www.ModelAviation.com
I made a small shield from a scrap
of 3/32 balsa and covered one side with
aluminum tape. This was epoxied over
the top of the fi n support and hollow area
of the fi n base to provide insulation to
the elevator spars, rudder servo, and wires,
because I prefer the extra protection.
The instructions for installing the
canopy base are straightforward, but I
found that I needed to grind some epoxy/
fi ller to get the provided hatch latch as far
back as possible. When epoxied in place,
it provided a positive and secure fi t.
Because this is a classic jet, I couldn’t
bring myself to leave the cockpit empty
or use a modern pilot, so I ordered a
1950s Saber Jock pilot bust from Jet
Hangar Hobbies.
Two evenings with good old Testors
model paints made me feel like a 12-yearold
again. I created a fast, scrap-wood
carriage bolt to allow both a gripping
action on the bottom, and a safety
edge/slot against the bolt loosening.
Additional wing stability is achieved
with a 6mm carbon-fi ber antirotation
dowel placed at the rear of the wing.
The wings aren’t complete without
the drop tanks and I chose to do
the modifi cation as described in the
instructions.
The engine access hatch is supported
and secured on both sides with a
plywood frame, but nothing in front or
behind. When I fi rst assembled the hatch,
it looked fi ne, until I took the airplane
out of my cool basement and into the
summer heat where it sagged.
A quick modifi cation with two strips
of 1/32 plywood provides support, and a
small square of 1/16 or 1/8 plywood in the
middle of the strips provides additional
grip for a retentive screw.
Now is a good time to install the tail
feathers. Both the stabilizer and the fi n
bases on the fuselage and surfaces need
to be roughened with coarse sandpaper
and small divots, to give “tooth” to the
epoxy. A strip of blue delicate surface
masking tape around the edges allows
easy cleanup of excess epoxy, and Hysol
9462 provides long-lasting strength.
Modellbau instructs that the incidence
of the stabilizers must not be changed.
The incidence obtained through the
drilled holes worked perfectly, and it’s
nice to see that the fl ight characteristics
were perfected prior to the model
hitting the market.
REVIEW
ejection seat and cockpit, and painted and
epoxied them in place. Given the shallow
space to work within the cockpit tray, I’m
happy with the way it turned out.
The canopy can be secured to the
base (while on the fuselage) with Goop,
canopy glue, or epoxy and held down
with strips of masking tape until dry.
Control Rods
Two interesting ways of doing control
rods came up during this build. Most
of us have either used a nut on one end
to prevent rotation in the clevis, or CA
hardened with kicker. Both are prone
to coming loose, and a nut can require
opening a pushrod slot more or changing
the position of the servo arm to prevent
banging or binding of the nut.
The fi rst method was suggested by
Modellbau. The provided pushrods are
Left: The left side of the fuselage shows the
easily installed and accessed dual switch gyro
and receiver, around the factory-installed plate.
The universal air trap (UAT) is easily accessed
when mounted to the front bulkhead.
Below: The engine hatch tended to collapse
inward because it lacked front and rear support.
The author epoxied 1/32 plywood strips to the
inside of the hatch opening to add support.www.ModelAviation.com March 2012 Model Aviation 71
Flying
Finally! If you read through the build
portion of this article, it was worth the
wait. I managed to fi nish in time to take
the F-86 to an event, but didn’t have
time to thoroughly go over everything.
After having two other sets of eyes
check linkages and movements, security
of surfaces and screws, balance and
retracts, we looked at throws. I checked
to see if I had a low rate programmed
into the radio and discovered I didn’t.
Two or three other issues were resolved,
but with everything triple-checked, I
nervously said, “Let’s go fl y.”
What a nonevent! That’s good on
a maiden fl ight. My fi rst three fl ights
were without the tanks, and the fi rst
takeoff was without the fl aps. A small
amount of up was needed since I was
slightly nose-heavy, and I added a bit of
aileron trim.
I was comfortable with the handling
and from the second fl ight on, low
passes were low and the full-speed range
was checked. I wished I’d had the full
45mm of fl ap defl ection, because the
aircraft wanted to continue fl oating
down the runway.
The next day, I added the drop tanks.
I had zero trim changes, and with the
power of the K-80 pushing, it is diffi cult
to guess if I needed to add one more
click of throttle.
The recommended settings for takeoff
fl ap work well, giving a smooth rotation.
Although it is recommended that the
fi rst fl ight be done without fl aps, I found
the rotation and departure easier and
more predictable with the fl aps.
I also found that a low rate of roughly
85% on ailerons gives a more scalelike
roll rate than the recommended setting.
Full fl aps, with the recommended
crow (also known as butterfl y or upailerons),
produced a stable, slow fl ight
regimen with a smooth fi nal approach
and complete aileron control all the
way to touchdown and rollout. The
recommended elevator trim was close.
Modellbau clearly did its homework.
Futaba GY 190 Gyro
This is the fi rst airplane in which I have
used a gyro. Modellbau recommends that
an inexpensive gyro, such as the GY 190,
be used on the rudder to counteract the
Dutch roll tendencies of many of the
early swept-wing fi ghters.
The company recommends a gain
setting of 25% as a starting point, which
produced some slight tail wag. Not
knowing if I had too much or too little
gain, I experimented with 35%, which
was way too much. I fi nally got it dialed
in at roughly 12%.
Several of the twin-boom fl iers at the
event routinely fl y their airplanes with
only threaded on one end; the idea is
to attach the supplied clevises to both
the servo arm and the control arm and
thread the pushrod onto one of them.
Mark the length to thread the smooth
end through the threads of the other
clevis and cut the pushrod. Thread the
smooth end forcibly into the clevis
and then solder that end together.
Adjustment is still available on the other
end and a jamb-nut is not needed.
In discussing this method with
several jet and large-model pilots, three
suggested using my favorite clevis (the
Sullivan Gold-N-Clevis) and 4-40 allthread,
but using J-B Weld instead of
soldering the end; this is what they had
been doing for years. (It was implied
that even I could mix two pastes
together and fi ll some threads.) This is
the method I used, but both work well.
The Modellbau demonstrator reportedly
made 250 fl ights without a problem.
Radio Needs
The F-86D requires 11 servos, plus
the throttle channel, so a nine-channel
radio system is the minimum radio
needed. To accomplish this, three
Equalizers or Match Boxes would be
needed for fl aps, elevators, and rudder/
nose gear. I don’t advise a fourth on
ailerons because the ability to activate
crow would be eliminated.
I used my Futaba 12Z transmitter
with a 6014HS, 14-channel receiver, 2.4
GHz radio system with Hitec servos.
The newer 12-channel radio systems
allow individual servos to be plugged
into the receiver and adjusted by the
transmitter’s internal functions. With
dual 6.6-volt Hobbico LiFe batteries
powering the onboard systems, there
are plenty of available electrons. This
ensures that the radio link is satisfi ed and
the servos have adequate power.
I’m happy to be able to fi ne-tune all
12 channels used with my transmitter.
Exponential is a subjective setting that
results in several arguments at the fi eld.
I typically only use 10-15% exponential,
and was using roughly 15-20% on both
the elevator and ailerons and did not
fi nd the model twitchy or soft. Just like
the gyro-gain setting, this needs to be
explored and fi ne-tuned.
The author
solved his
worries about
heat in the fi n
with a piece
of 3/32 balsa
covered with
aluminum
tape, then
epoxied
over the fi n
concavity.72 Model Aviation March 2012 www.ModelAviation.com
REVIEW
60-100% gain; however, I discovered
that a higher gain made the F-86 look
like a fi sh as it wiggled its way past me.
Conclusion
Modellbau has a winner! The F-86D
is a stable, enjoyable aircraft with a
huge fl ight envelope that looks great
and behaves well in the air. If you are
profi cient with a “full-house” warbirdtype
airplane, it could easily pull double
duty as a turbine-powered jet trainer as
well as a Scale airplane.
The trailing link struts from Spring
Air do not look out of place because
they remain straight under all but very
heavy landing loads. The wheels and
brakes work well, with consistent and
predictable braking action.
This airplane really is a two-thumbsup
purchase.
—Greg Moore
jetfl [email protected]
Charles Scarborough took this photo of the maiden fl ight at rotation. Takeoffs are far easier and more predictable using fl aps.
The painted pilot bust is in place on its ejection seat constructed from balsa
and fi berglass sheet.SourceS:
Modellbau uSA
(954) 224-1700
www.modellbauusa.
com
KingTech Turbines
(626) 793-4677
www.kingtechturbines.
com
Jetcat uSA
(805) 226-8700
www.jetcatusa.com
Spring Air Products
(321)728-9002
www.retracts.com
Jet Hangar Hobbies
(562) 467-0260
www.jethangar.com
McMaster-carr
(562) 462-4277
www.mcmaster.com
Micro Fasteners
(800) 892-6917
www.microfasteners.
com
Valley View rc
(253) 875-6890
www.valleyviewrc.com
Tower Hobbies
(800) 637-6050
www.towerhobbies.
com

www.ModelAviation.com March 2012 Model Aviation 65
The F-86 is one of the best known of the jet fi ghters and a participant in MiG
Alley during the Korean War. The aircraft starred in many movies and began
life as the straight-wing North American Aviation FJ-1 Fury. When that
version did not meet design criteria, among other changes, a 35° swept wing was
substituted, and in 1947 the YF-86 took to the skies.
With the fear of hordes of Soviet bombers attacking the US, work on a bomber
interceptor, the F-95A, began. The aircraft was renamed the F-86D and was wider
and longer, with a larger engine and a clamshell canopy. It was the fi rst Air Force
night fi ghter with a single engine and a single pilot.
The Sabre was only slightly similar to the other variants. It had a retractable tray
in the belly that held 24 2.75-inch Mighty Mouse Mk 4 Rockets instead of guns. It
was believed that the rockets would be more effective against a bomber formation,
especially at night.
Another variety was marketed as a NATO fi ghter. This model, known as the
F-86K, had the rocket tray replaced with four 20mm cannons. It was painted in a
number of color and camoufl age schemes.
Having had several versions of the venerable F-86, both electric-powered ductedfan
(EDF) models and glow-powered ducted-fan aircraft, I was thrilled to review this
release from ModellbauUSA.
I believe only two models of the F-86D have been produced—one many years ago
by Byron, and a propeller-jet version imported by Nitro Models. This version was
designed for turbine power, specifi cally the JetCat P60, with the focus on weight
management and simplicity.
Converting to EDF is as simple as replacing the stainless steel turbine tailpipe
with a Mylar tube and adding intake ducting. Adequate strength is needed to
accommodate the more powerful, heavier KingTech K-80 (which I used in this
review) and this has been designed in.
Is this a totally Scale, “let’s go to the Jet World Masters” aircraft? No. It is a Sport
Scale version of the most numerous variant of the Sabre. Scale fi delity in landing
gear placement is sacrifi ced for a wider and more stable confi guration, along with
slightly more wing area.
The model presents well in the air. This was taken shortly after liftoff. Charles Scarborough photo.
A turbine that’s
friendly to fi rsttime
jet pilots
Greg Moore
REVIEW MODELLBAU USA F-86D DOG SABRE jetfl [email protected]
Photos by the author unless noted66 Model Aviation March 2012 www.ModelAviation.com
If you are a Scale junkie, this airplane
is not for you; however, if you want
an attractive replica of a great-fl ying
airplane with a wide speed range and
fantastic ground handling added, this
might be for you.
The model is roughly the same
price as many of the larger ARFs in
the current Tower Hobbies catalog.
Modellbau has decided to sell the
aircraft, which is designed around the
15- to 20-pound thrust engines, in a
transportable size at a reasonable price.
Unpacking
The model is well-packed, but the
one I received suffered mild cracking
in the tail during shipping. It was easily
repaired, and is a testimony to the
correct strength and number of fi berglass
layers used in the layup.
The box includes a nicely fabricated
and painted fi berglass fuselage, sheeted
built-up wings, and tail feathers with
iron-on covering and stick-on decals.
Spring Air’s new, red, heavy-duty landing
gear is preinstalled. The package also
includes a prepainted, modern jet pilot
fi gure, lightweight, dual-walled tailpipe,
custom fi berglass fuel tanks, and all the
linkage hardware needed to assemble
the airplane.
You will need to purchase struts,
wheels, and brakes (I used the Spring
Air/Modellbau combination package),
as well as engine and radio components.
I used the KingTech K-80f, kero-start
engine, which I will discuss later.
Building the Dog Sabre
Because the instructions are
straightforward and available online
as a PDF, I will not give a step-by-step
review. Instead, I will assess items that
need clarifi cation, are interesting, or have
changed.
The fi rst topic is hinging all of the
control surfaces. You should be able
to open and check the contents of the
box, unpack everything, seal and shrink
the wrinkles in the covering, and hinge
your surfaces in one evening, or part of
a weekend day. The precut slots are that
well done.
Make sure you open/bevel the hinge
slots so the hinges are slightly recessed
to minimize the gaps. Lubricate your
hinge with some melted Vaseline, and
use a good, slow-setting epoxy such as
Hysol 9462 or E-20HP (available from
McMaster-Carr online, or your local
Fastenal store).
The only item of note in this part of
the assembly concerns the fl aps. The
SPECIFICATIONS
Type Sport Scale turbine jet
Skill level Intermediate builder;
intermediate pilot
Wingspan 60 inches
Wing area 895 square inches
Length 68 inches
Flying weight 15 pounds
engine 12- to 18-pound thrust turbine (or
large electric-powered ducted fan).
Recommended JetCat P60 or KingTech K-80
engines
Radio Nine-channel minimum with 11
servos
Construction Composite fuselage with builtup
sheeted wings and tail
Covering/fi nish Painted fi berglass fuselage,
iron-on covering on sheeted
parts
Street price $760
TEST-MODEL DETAILS
Engine KingTech K-80F
Radio system Futaba 12Z transmitter, Futaba
FASST 6014HS receiver, Futaba
GY 190 gyro
Ready-to-fl y 16 pounds, 2 ounces
weight
Flight duration 9 to 10 minutes
KINGTECH K-80F SPECIFICATIONS
Diameter 3¾ inches (95.25mm)
Length 10 inches (254mm) including
starter
Weight 2 pounds, 14 ounces (1304 g)
including starter
Maximum rpm 145,000
Thrust 19 pounds at 70° F
Idle 45,000 rpm
Exhaust 1202° F (650° C) maximum
temperature
Fuel 8.46 ounces per minute
consumption (239 grams per minute)
Maintenance 25 hours
cycle
Oil 5% Turbine oil
PLUSES
• Uses a wide range and selection of engine sizes.
• Gentle, predictable handling and performs well.
• Could be used as a fi rst jet.
• All included hardware is high quality.
MINUSES
• Landing gear too long for Scale appearance.
• Canopy could be constructed from clearer/
thicker material.
AT A GLANCE....
REVIEW
Everything needed to operate the engine is included with the exception of a battery pack.
Quality components are used throughout.www.ModelAviation.com March 2012 Model Aviation 67
incorrectly plug in the wires.
The rudder and elevator servos are
mounted inside the fin and stabilizers.
The rudder servo mounting is
straightforward. Add two hardwood
blocks to the hatch to fit the suggested
Hitec 5245MG servo, allowing the
control arm to center in the precut slot,
and then mount the hatch. The elevator
servos required more thought because
the stabilizers are so thin.
Modellbau recommends a thin-wing
servo with metal gears and at least 65
ounce-inches of torque for the elevators.
I used the JR Radios digital 378 thinwing
servo that meets the criteria.
It seemed to be designed to mount
against a hatch or surface, so I decided to
mount the servo to the hatch with four
4-40 machine screws through the four
mounting lugs. The rear set went all the
way through the double lugs, while the
front set had the lock, washer, and nut
between the lugs.
I cut a piece of ¼-inch aircraft-grade
plywood to fit snugly between the lugs
and fit against the front and rear spars,
trimmed them to the correct thickness
to allow the hatch to fit flush with the
bottom skin, and then epoxied them
into place using the hatch/servo to
position things.
Spring Air’s Red Jet series of
retracts are included in the kit
and feature larger cylinders and
springs to handle higher speeds.
The optional trailing link struts
look nice and function well.
precut and beveled flaps are hinged in
the middle of the surface, which allows
only 35mm of flap deflection. This is
perfect for a small engine such as the
JetCat P60, but can’t generate the 45mm
of deflection needed for a larger engine.
If you plan to use a KingTech K-80,
JetCat P70, Wren 70, or Super Sport,
the bevel in the flap should be filled
with a ¼-inch balsa strip and then
hinged at the bottom. My model could
have benefitted from the full 45mm of
flap deflection.
Keeping things as simple as possible,
Modellbau designed the aircraft to have
the servos outside of the wing; just
harden the holes with some thin CA and
screw them in.
The recommended servo for both
ailerons and flaps is the Hitec 645MG,
but since I still have 12 new 605s, I used
these. Control horn placement is as easy
as cutting a slot, setting the horn with
Hysol E20HP, and letting it cure.
I like to protect my wiring connections
from myself. With two servo leads to
the wings, and because I have managed
to connect the wrong pair in the past,
I eliminated that problem by using a
six-pin Multiplex connector. With each
extension wired to it, it’s impossible to
The well-protected contents include everything but glue, electronics, and an engine.68 Model Aviation March 2012 www.ModelAviation.com
I would have liked to move the engine
farther forward to help with balancing,
but the 1/2-inch gap I needed between
the engine and pipe dictated the fi nal
engine position. It is a good idea to fi t the
pipe-support mount and secure it with
epoxy mixed with fi berglass millings.
My next step was fi guring out where
I could neatly place everything that
needed to go into the fuselage—as
far forward as possible for balancing
purposes. I made a 1/8-inch plywood
REVIEW
Servo wires running to the
elevators and rudder pass close
to the tail pipe, so cover them
with aluminum heating-duct
tape or a heat shield.
The author slightly
scalloped the exit
opening on the bottom
to allow the stainless
steel pipe to exit the
fuselage.
When the engine mounting rails are correctly trimmed, the engine fi ts
evenly within them.
The elevator/servo openings are shallow, requiring a thin-wing servo and
creativity in mounting. Greg fabricated 1/4-inch plywood plates that fi t
snugly within the servo mounting lugs.
ended up with a scallop to allow the
pipe to exit.
Before installing the pipe supports, run
the servo wires to the rear and protect
them with aluminum tape or heat shield.
With the servo leads secure, the engine
can be fi tted through the bottom hatch
and onto the rails. The rails are narrow
enough for a P60 without needing to
add material. With the wider K-80, all I
had to do was remove a small amount of
wood to set the engine in place.
When dry, the hatch was screwed
to the ¼-inch plywood mounts with
servo screws from Micro Fasteners,
and the control horn was placed as
described earlier.
Now is a good time to open the rear
of the fuselage enough to allow the tail
pipe to exit. The hole is only a rough
opening, allowing those using their
pipe of choice to get the correct fi t. I
found that 90% of the trimming
I needed was on the bottom, andplate that screwed into some ¼-inch
plywood blocks with servo screws on
the right side, and used the already
installed mounting plates to mount
the Spring Air retract valve and dual
switch. Designed for large, gas-powered
engines, the switch is robust, has a small
mounting footprint, and snaps into on or
off position, as well as charge leads.
Likewise, I mounted the ECU to a
plywood plate epoxied to the bottom
of the fuselage. It’s easy to connect to
the ground-support unit and I like to
monitor the start information.
I use dual receiver packs with separate
switches into separate ports in the
receiver on my jets, so space was needed
for a pair of Hobbico LiFe 6.6-volt, 2100
mAh packs and the provided 9.9-volt
A123-LiFe pump pack in a secure spot
that was as far forward as possible.
The receiver packs can be mounted
with Velcro alongside the nose gear rails,
and the pump pack can be mounted
along with the retract air tank above the
inlet in the radome. It’s diffi cult to place
these heavier objects any farther forward.
This large space becomes small
quickly, and it gets even smaller when
you assemble the fuel tanks. I had to
open the existing hole in the bulkhead
to allow the fuel tank cap and lines to
come through smoothly. I trimmed
roughly 3/8 inch from the fl ange on top
of the fuselage to allow the tanks to
enter easily.
A thin piece of plywood was needed
beneath the inside edge of the tanks
so they would fi t fl ush with the sides
of the fuselage. Goop, PFM, or other
silicone adhesive between the tanks
and sides will keep the tanks in place.
With two tubular spars running through
the fuselage, it is important that the
servo leads and fuel and air lines are
secured to the fuselage with keepers or
attachments.
The Spring Air struts were mounted
into their retract units, given some
toe-in, then slowly retracted to avoid
smashing into the top skin. I had to
remove some of the wing rib, and shim
the landing gear to prevent it from
wedging against the top of the wing.
When I was happy with the fi t, I
made wheel well inserts to keep large
masses of air out of the wing. A hint Ifound online suggested I use an empty
cereal box, trimmed to shape, and
use my favorite Bob Smith Industries
medium CA to secure it in place. A coat
of thinned epoxy gave it fuel and water
protection and I was done.
To secure the wings to the fuselage,
carefully measure then drill a hole for
a ¼-20 bolt. If you have small hands,
a thumbscrew could be used to attachthe wing. I had to insert a carriage bolt
that I cut the head off of into the
blind nut in the wing and secure it
with blue threadlocker. This bolt goes
into the fuselage and through a ¼-inch
wheel collar that is secured within a
plywood block and epoxied to the side
of the fuselage.
An 8-32 bolt is substituted for the
setscrew and a fl at slot is cut into the70 Model Aviation March 2012 www.ModelAviation.com
I made a small shield from a scrap
of 3/32 balsa and covered one side with
aluminum tape. This was epoxied over
the top of the fi n support and hollow area
of the fi n base to provide insulation to
the elevator spars, rudder servo, and wires,
because I prefer the extra protection.
The instructions for installing the
canopy base are straightforward, but I
found that I needed to grind some epoxy/
fi ller to get the provided hatch latch as far
back as possible. When epoxied in place,
it provided a positive and secure fi t.
Because this is a classic jet, I couldn’t
bring myself to leave the cockpit empty
or use a modern pilot, so I ordered a
1950s Saber Jock pilot bust from Jet
Hangar Hobbies.
Two evenings with good old Testors
model paints made me feel like a 12-yearold
again. I created a fast, scrap-wood
carriage bolt to allow both a gripping
action on the bottom, and a safety
edge/slot against the bolt loosening.
Additional wing stability is achieved
with a 6mm carbon-fi ber antirotation
dowel placed at the rear of the wing.
The wings aren’t complete without
the drop tanks and I chose to do
the modifi cation as described in the
instructions.
The engine access hatch is supported
and secured on both sides with a
plywood frame, but nothing in front or
behind. When I fi rst assembled the hatch,
it looked fi ne, until I took the airplane
out of my cool basement and into the
summer heat where it sagged.
A quick modifi cation with two strips
of 1/32 plywood provides support, and a
small square of 1/16 or 1/8 plywood in the
middle of the strips provides additional
grip for a retentive screw.
Now is a good time to install the tail
feathers. Both the stabilizer and the fi n
bases on the fuselage and surfaces need
to be roughened with coarse sandpaper
and small divots, to give “tooth” to the
epoxy. A strip of blue delicate surface
masking tape around the edges allows
easy cleanup of excess epoxy, and Hysol
9462 provides long-lasting strength.
Modellbau instructs that the incidence
of the stabilizers must not be changed.
The incidence obtained through the
drilled holes worked perfectly, and it’s
nice to see that the fl ight characteristics
were perfected prior to the model
hitting the market.
REVIEW
ejection seat and cockpit, and painted and
epoxied them in place. Given the shallow
space to work within the cockpit tray, I’m
happy with the way it turned out.
The canopy can be secured to the
base (while on the fuselage) with Goop,
canopy glue, or epoxy and held down
with strips of masking tape until dry.
Control Rods
Two interesting ways of doing control
rods came up during this build. Most
of us have either used a nut on one end
to prevent rotation in the clevis, or CA
hardened with kicker. Both are prone
to coming loose, and a nut can require
opening a pushrod slot more or changing
the position of the servo arm to prevent
banging or binding of the nut.
The fi rst method was suggested by
Modellbau. The provided pushrods are
Left: The left side of the fuselage shows the
easily installed and accessed dual switch gyro
and receiver, around the factory-installed plate.
The universal air trap (UAT) is easily accessed
when mounted to the front bulkhead.
Below: The engine hatch tended to collapse
inward because it lacked front and rear support.
The author epoxied 1/32 plywood strips to the
inside of the hatch opening to add support.www.ModelAviation.com March 2012 Model Aviation 71
Flying
Finally! If you read through the build
portion of this article, it was worth the
wait. I managed to fi nish in time to take
the F-86 to an event, but didn’t have
time to thoroughly go over everything.
After having two other sets of eyes
check linkages and movements, security
of surfaces and screws, balance and
retracts, we looked at throws. I checked
to see if I had a low rate programmed
into the radio and discovered I didn’t.
Two or three other issues were resolved,
but with everything triple-checked, I
nervously said, “Let’s go fl y.”
What a nonevent! That’s good on
a maiden fl ight. My fi rst three fl ights
were without the tanks, and the fi rst
takeoff was without the fl aps. A small
amount of up was needed since I was
slightly nose-heavy, and I added a bit of
aileron trim.
I was comfortable with the handling
and from the second fl ight on, low
passes were low and the full-speed range
was checked. I wished I’d had the full
45mm of fl ap defl ection, because the
aircraft wanted to continue fl oating
down the runway.
The next day, I added the drop tanks.
I had zero trim changes, and with the
power of the K-80 pushing, it is diffi cult
to guess if I needed to add one more
click of throttle.
The recommended settings for takeoff
fl ap work well, giving a smooth rotation.
Although it is recommended that the
fi rst fl ight be done without fl aps, I found
the rotation and departure easier and
more predictable with the fl aps.
I also found that a low rate of roughly
85% on ailerons gives a more scalelike
roll rate than the recommended setting.
Full fl aps, with the recommended
crow (also known as butterfl y or upailerons),
produced a stable, slow fl ight
regimen with a smooth fi nal approach
and complete aileron control all the
way to touchdown and rollout. The
recommended elevator trim was close.
Modellbau clearly did its homework.
Futaba GY 190 Gyro
This is the fi rst airplane in which I have
used a gyro. Modellbau recommends that
an inexpensive gyro, such as the GY 190,
be used on the rudder to counteract the
Dutch roll tendencies of many of the
early swept-wing fi ghters.
The company recommends a gain
setting of 25% as a starting point, which
produced some slight tail wag. Not
knowing if I had too much or too little
gain, I experimented with 35%, which
was way too much. I fi nally got it dialed
in at roughly 12%.
Several of the twin-boom fl iers at the
event routinely fl y their airplanes with
only threaded on one end; the idea is
to attach the supplied clevises to both
the servo arm and the control arm and
thread the pushrod onto one of them.
Mark the length to thread the smooth
end through the threads of the other
clevis and cut the pushrod. Thread the
smooth end forcibly into the clevis
and then solder that end together.
Adjustment is still available on the other
end and a jamb-nut is not needed.
In discussing this method with
several jet and large-model pilots, three
suggested using my favorite clevis (the
Sullivan Gold-N-Clevis) and 4-40 allthread,
but using J-B Weld instead of
soldering the end; this is what they had
been doing for years. (It was implied
that even I could mix two pastes
together and fi ll some threads.) This is
the method I used, but both work well.
The Modellbau demonstrator reportedly
made 250 fl ights without a problem.
Radio Needs
The F-86D requires 11 servos, plus
the throttle channel, so a nine-channel
radio system is the minimum radio
needed. To accomplish this, three
Equalizers or Match Boxes would be
needed for fl aps, elevators, and rudder/
nose gear. I don’t advise a fourth on
ailerons because the ability to activate
crow would be eliminated.
I used my Futaba 12Z transmitter
with a 6014HS, 14-channel receiver, 2.4
GHz radio system with Hitec servos.
The newer 12-channel radio systems
allow individual servos to be plugged
into the receiver and adjusted by the
transmitter’s internal functions. With
dual 6.6-volt Hobbico LiFe batteries
powering the onboard systems, there
are plenty of available electrons. This
ensures that the radio link is satisfi ed and
the servos have adequate power.
I’m happy to be able to fi ne-tune all
12 channels used with my transmitter.
Exponential is a subjective setting that
results in several arguments at the fi eld.
I typically only use 10-15% exponential,
and was using roughly 15-20% on both
the elevator and ailerons and did not
fi nd the model twitchy or soft. Just like
the gyro-gain setting, this needs to be
explored and fi ne-tuned.
The author
solved his
worries about
heat in the fi n
with a piece
of 3/32 balsa
covered with
aluminum
tape, then
epoxied
over the fi n
concavity.72 Model Aviation March 2012 www.ModelAviation.com
REVIEW
60-100% gain; however, I discovered
that a higher gain made the F-86 look
like a fi sh as it wiggled its way past me.
Conclusion
Modellbau has a winner! The F-86D
is a stable, enjoyable aircraft with a
huge fl ight envelope that looks great
and behaves well in the air. If you are
profi cient with a “full-house” warbirdtype
airplane, it could easily pull double
duty as a turbine-powered jet trainer as
well as a Scale airplane.
The trailing link struts from Spring
Air do not look out of place because
they remain straight under all but very
heavy landing loads. The wheels and
brakes work well, with consistent and
predictable braking action.
This airplane really is a two-thumbsup
purchase.
—Greg Moore
jetfl [email protected]
Charles Scarborough took this photo of the maiden fl ight at rotation. Takeoffs are far easier and more predictable using fl aps.
The painted pilot bust is in place on its ejection seat constructed from balsa
and fi berglass sheet.SourceS:
Modellbau uSA
(954) 224-1700
www.modellbauusa.
com
KingTech Turbines
(626) 793-4677
www.kingtechturbines.
com
Jetcat uSA
(805) 226-8700
www.jetcatusa.com
Spring Air Products
(321)728-9002
www.retracts.com
Jet Hangar Hobbies
(562) 467-0260
www.jethangar.com
McMaster-carr
(562) 462-4277
www.mcmaster.com
Micro Fasteners
(800) 892-6917
www.microfasteners.
com
Valley View rc
(253) 875-6890
www.valleyviewrc.com
Tower Hobbies
(800) 637-6050
www.towerhobbies.
com

www.ModelAviation.com March 2012 Model Aviation 65
The F-86 is one of the best known of the jet fi ghters and a participant in MiG
Alley during the Korean War. The aircraft starred in many movies and began
life as the straight-wing North American Aviation FJ-1 Fury. When that
version did not meet design criteria, among other changes, a 35° swept wing was
substituted, and in 1947 the YF-86 took to the skies.
With the fear of hordes of Soviet bombers attacking the US, work on a bomber
interceptor, the F-95A, began. The aircraft was renamed the F-86D and was wider
and longer, with a larger engine and a clamshell canopy. It was the fi rst Air Force
night fi ghter with a single engine and a single pilot.
The Sabre was only slightly similar to the other variants. It had a retractable tray
in the belly that held 24 2.75-inch Mighty Mouse Mk 4 Rockets instead of guns. It
was believed that the rockets would be more effective against a bomber formation,
especially at night.
Another variety was marketed as a NATO fi ghter. This model, known as the
F-86K, had the rocket tray replaced with four 20mm cannons. It was painted in a
number of color and camoufl age schemes.
Having had several versions of the venerable F-86, both electric-powered ductedfan
(EDF) models and glow-powered ducted-fan aircraft, I was thrilled to review this
release from ModellbauUSA.
I believe only two models of the F-86D have been produced—one many years ago
by Byron, and a propeller-jet version imported by Nitro Models. This version was
designed for turbine power, specifi cally the JetCat P60, with the focus on weight
management and simplicity.
Converting to EDF is as simple as replacing the stainless steel turbine tailpipe
with a Mylar tube and adding intake ducting. Adequate strength is needed to
accommodate the more powerful, heavier KingTech K-80 (which I used in this
review) and this has been designed in.
Is this a totally Scale, “let’s go to the Jet World Masters” aircraft? No. It is a Sport
Scale version of the most numerous variant of the Sabre. Scale fi delity in landing
gear placement is sacrifi ced for a wider and more stable confi guration, along with
slightly more wing area.
The model presents well in the air. This was taken shortly after liftoff. Charles Scarborough photo.
A turbine that’s
friendly to fi rsttime
jet pilots
Greg Moore
REVIEW MODELLBAU USA F-86D DOG SABRE jetfl [email protected]
Photos by the author unless noted66 Model Aviation March 2012 www.ModelAviation.com
If you are a Scale junkie, this airplane
is not for you; however, if you want
an attractive replica of a great-fl ying
airplane with a wide speed range and
fantastic ground handling added, this
might be for you.
The model is roughly the same
price as many of the larger ARFs in
the current Tower Hobbies catalog.
Modellbau has decided to sell the
aircraft, which is designed around the
15- to 20-pound thrust engines, in a
transportable size at a reasonable price.
Unpacking
The model is well-packed, but the
one I received suffered mild cracking
in the tail during shipping. It was easily
repaired, and is a testimony to the
correct strength and number of fi berglass
layers used in the layup.
The box includes a nicely fabricated
and painted fi berglass fuselage, sheeted
built-up wings, and tail feathers with
iron-on covering and stick-on decals.
Spring Air’s new, red, heavy-duty landing
gear is preinstalled. The package also
includes a prepainted, modern jet pilot
fi gure, lightweight, dual-walled tailpipe,
custom fi berglass fuel tanks, and all the
linkage hardware needed to assemble
the airplane.
You will need to purchase struts,
wheels, and brakes (I used the Spring
Air/Modellbau combination package),
as well as engine and radio components.
I used the KingTech K-80f, kero-start
engine, which I will discuss later.
Building the Dog Sabre
Because the instructions are
straightforward and available online
as a PDF, I will not give a step-by-step
review. Instead, I will assess items that
need clarifi cation, are interesting, or have
changed.
The fi rst topic is hinging all of the
control surfaces. You should be able
to open and check the contents of the
box, unpack everything, seal and shrink
the wrinkles in the covering, and hinge
your surfaces in one evening, or part of
a weekend day. The precut slots are that
well done.
Make sure you open/bevel the hinge
slots so the hinges are slightly recessed
to minimize the gaps. Lubricate your
hinge with some melted Vaseline, and
use a good, slow-setting epoxy such as
Hysol 9462 or E-20HP (available from
McMaster-Carr online, or your local
Fastenal store).
The only item of note in this part of
the assembly concerns the fl aps. The
SPECIFICATIONS
Type Sport Scale turbine jet
Skill level Intermediate builder;
intermediate pilot
Wingspan 60 inches
Wing area 895 square inches
Length 68 inches
Flying weight 15 pounds
engine 12- to 18-pound thrust turbine (or
large electric-powered ducted fan).
Recommended JetCat P60 or KingTech K-80
engines
Radio Nine-channel minimum with 11
servos
Construction Composite fuselage with builtup
sheeted wings and tail
Covering/fi nish Painted fi berglass fuselage,
iron-on covering on sheeted
parts
Street price $760
TEST-MODEL DETAILS
Engine KingTech K-80F
Radio system Futaba 12Z transmitter, Futaba
FASST 6014HS receiver, Futaba
GY 190 gyro
Ready-to-fl y 16 pounds, 2 ounces
weight
Flight duration 9 to 10 minutes
KINGTECH K-80F SPECIFICATIONS
Diameter 3¾ inches (95.25mm)
Length 10 inches (254mm) including
starter
Weight 2 pounds, 14 ounces (1304 g)
including starter
Maximum rpm 145,000
Thrust 19 pounds at 70° F
Idle 45,000 rpm
Exhaust 1202° F (650° C) maximum
temperature
Fuel 8.46 ounces per minute
consumption (239 grams per minute)
Maintenance 25 hours
cycle
Oil 5% Turbine oil
PLUSES
• Uses a wide range and selection of engine sizes.
• Gentle, predictable handling and performs well.
• Could be used as a fi rst jet.
• All included hardware is high quality.
MINUSES
• Landing gear too long for Scale appearance.
• Canopy could be constructed from clearer/
thicker material.
AT A GLANCE....
REVIEW
Everything needed to operate the engine is included with the exception of a battery pack.
Quality components are used throughout.www.ModelAviation.com March 2012 Model Aviation 67
incorrectly plug in the wires.
The rudder and elevator servos are
mounted inside the fin and stabilizers.
The rudder servo mounting is
straightforward. Add two hardwood
blocks to the hatch to fit the suggested
Hitec 5245MG servo, allowing the
control arm to center in the precut slot,
and then mount the hatch. The elevator
servos required more thought because
the stabilizers are so thin.
Modellbau recommends a thin-wing
servo with metal gears and at least 65
ounce-inches of torque for the elevators.
I used the JR Radios digital 378 thinwing
servo that meets the criteria.
It seemed to be designed to mount
against a hatch or surface, so I decided to
mount the servo to the hatch with four
4-40 machine screws through the four
mounting lugs. The rear set went all the
way through the double lugs, while the
front set had the lock, washer, and nut
between the lugs.
I cut a piece of ¼-inch aircraft-grade
plywood to fit snugly between the lugs
and fit against the front and rear spars,
trimmed them to the correct thickness
to allow the hatch to fit flush with the
bottom skin, and then epoxied them
into place using the hatch/servo to
position things.
Spring Air’s Red Jet series of
retracts are included in the kit
and feature larger cylinders and
springs to handle higher speeds.
The optional trailing link struts
look nice and function well.
precut and beveled flaps are hinged in
the middle of the surface, which allows
only 35mm of flap deflection. This is
perfect for a small engine such as the
JetCat P60, but can’t generate the 45mm
of deflection needed for a larger engine.
If you plan to use a KingTech K-80,
JetCat P70, Wren 70, or Super Sport,
the bevel in the flap should be filled
with a ¼-inch balsa strip and then
hinged at the bottom. My model could
have benefitted from the full 45mm of
flap deflection.
Keeping things as simple as possible,
Modellbau designed the aircraft to have
the servos outside of the wing; just
harden the holes with some thin CA and
screw them in.
The recommended servo for both
ailerons and flaps is the Hitec 645MG,
but since I still have 12 new 605s, I used
these. Control horn placement is as easy
as cutting a slot, setting the horn with
Hysol E20HP, and letting it cure.
I like to protect my wiring connections
from myself. With two servo leads to
the wings, and because I have managed
to connect the wrong pair in the past,
I eliminated that problem by using a
six-pin Multiplex connector. With each
extension wired to it, it’s impossible to
The well-protected contents include everything but glue, electronics, and an engine.68 Model Aviation March 2012 www.ModelAviation.com
I would have liked to move the engine
farther forward to help with balancing,
but the 1/2-inch gap I needed between
the engine and pipe dictated the fi nal
engine position. It is a good idea to fi t the
pipe-support mount and secure it with
epoxy mixed with fi berglass millings.
My next step was fi guring out where
I could neatly place everything that
needed to go into the fuselage—as
far forward as possible for balancing
purposes. I made a 1/8-inch plywood
REVIEW
Servo wires running to the
elevators and rudder pass close
to the tail pipe, so cover them
with aluminum heating-duct
tape or a heat shield.
The author slightly
scalloped the exit
opening on the bottom
to allow the stainless
steel pipe to exit the
fuselage.
When the engine mounting rails are correctly trimmed, the engine fi ts
evenly within them.
The elevator/servo openings are shallow, requiring a thin-wing servo and
creativity in mounting. Greg fabricated 1/4-inch plywood plates that fi t
snugly within the servo mounting lugs.
ended up with a scallop to allow the
pipe to exit.
Before installing the pipe supports, run
the servo wires to the rear and protect
them with aluminum tape or heat shield.
With the servo leads secure, the engine
can be fi tted through the bottom hatch
and onto the rails. The rails are narrow
enough for a P60 without needing to
add material. With the wider K-80, all I
had to do was remove a small amount of
wood to set the engine in place.
When dry, the hatch was screwed
to the ¼-inch plywood mounts with
servo screws from Micro Fasteners,
and the control horn was placed as
described earlier.
Now is a good time to open the rear
of the fuselage enough to allow the tail
pipe to exit. The hole is only a rough
opening, allowing those using their
pipe of choice to get the correct fi t. I
found that 90% of the trimming
I needed was on the bottom, andplate that screwed into some ¼-inch
plywood blocks with servo screws on
the right side, and used the already
installed mounting plates to mount
the Spring Air retract valve and dual
switch. Designed for large, gas-powered
engines, the switch is robust, has a small
mounting footprint, and snaps into on or
off position, as well as charge leads.
Likewise, I mounted the ECU to a
plywood plate epoxied to the bottom
of the fuselage. It’s easy to connect to
the ground-support unit and I like to
monitor the start information.
I use dual receiver packs with separate
switches into separate ports in the
receiver on my jets, so space was needed
for a pair of Hobbico LiFe 6.6-volt, 2100
mAh packs and the provided 9.9-volt
A123-LiFe pump pack in a secure spot
that was as far forward as possible.
The receiver packs can be mounted
with Velcro alongside the nose gear rails,
and the pump pack can be mounted
along with the retract air tank above the
inlet in the radome. It’s diffi cult to place
these heavier objects any farther forward.
This large space becomes small
quickly, and it gets even smaller when
you assemble the fuel tanks. I had to
open the existing hole in the bulkhead
to allow the fuel tank cap and lines to
come through smoothly. I trimmed
roughly 3/8 inch from the fl ange on top
of the fuselage to allow the tanks to
enter easily.
A thin piece of plywood was needed
beneath the inside edge of the tanks
so they would fi t fl ush with the sides
of the fuselage. Goop, PFM, or other
silicone adhesive between the tanks
and sides will keep the tanks in place.
With two tubular spars running through
the fuselage, it is important that the
servo leads and fuel and air lines are
secured to the fuselage with keepers or
attachments.
The Spring Air struts were mounted
into their retract units, given some
toe-in, then slowly retracted to avoid
smashing into the top skin. I had to
remove some of the wing rib, and shim
the landing gear to prevent it from
wedging against the top of the wing.
When I was happy with the fi t, I
made wheel well inserts to keep large
masses of air out of the wing. A hint Ifound online suggested I use an empty
cereal box, trimmed to shape, and
use my favorite Bob Smith Industries
medium CA to secure it in place. A coat
of thinned epoxy gave it fuel and water
protection and I was done.
To secure the wings to the fuselage,
carefully measure then drill a hole for
a ¼-20 bolt. If you have small hands,
a thumbscrew could be used to attachthe wing. I had to insert a carriage bolt
that I cut the head off of into the
blind nut in the wing and secure it
with blue threadlocker. This bolt goes
into the fuselage and through a ¼-inch
wheel collar that is secured within a
plywood block and epoxied to the side
of the fuselage.
An 8-32 bolt is substituted for the
setscrew and a fl at slot is cut into the70 Model Aviation March 2012 www.ModelAviation.com
I made a small shield from a scrap
of 3/32 balsa and covered one side with
aluminum tape. This was epoxied over
the top of the fi n support and hollow area
of the fi n base to provide insulation to
the elevator spars, rudder servo, and wires,
because I prefer the extra protection.
The instructions for installing the
canopy base are straightforward, but I
found that I needed to grind some epoxy/
fi ller to get the provided hatch latch as far
back as possible. When epoxied in place,
it provided a positive and secure fi t.
Because this is a classic jet, I couldn’t
bring myself to leave the cockpit empty
or use a modern pilot, so I ordered a
1950s Saber Jock pilot bust from Jet
Hangar Hobbies.
Two evenings with good old Testors
model paints made me feel like a 12-yearold
again. I created a fast, scrap-wood
carriage bolt to allow both a gripping
action on the bottom, and a safety
edge/slot against the bolt loosening.
Additional wing stability is achieved
with a 6mm carbon-fi ber antirotation
dowel placed at the rear of the wing.
The wings aren’t complete without
the drop tanks and I chose to do
the modifi cation as described in the
instructions.
The engine access hatch is supported
and secured on both sides with a
plywood frame, but nothing in front or
behind. When I fi rst assembled the hatch,
it looked fi ne, until I took the airplane
out of my cool basement and into the
summer heat where it sagged.
A quick modifi cation with two strips
of 1/32 plywood provides support, and a
small square of 1/16 or 1/8 plywood in the
middle of the strips provides additional
grip for a retentive screw.
Now is a good time to install the tail
feathers. Both the stabilizer and the fi n
bases on the fuselage and surfaces need
to be roughened with coarse sandpaper
and small divots, to give “tooth” to the
epoxy. A strip of blue delicate surface
masking tape around the edges allows
easy cleanup of excess epoxy, and Hysol
9462 provides long-lasting strength.
Modellbau instructs that the incidence
of the stabilizers must not be changed.
The incidence obtained through the
drilled holes worked perfectly, and it’s
nice to see that the fl ight characteristics
were perfected prior to the model
hitting the market.
REVIEW
ejection seat and cockpit, and painted and
epoxied them in place. Given the shallow
space to work within the cockpit tray, I’m
happy with the way it turned out.
The canopy can be secured to the
base (while on the fuselage) with Goop,
canopy glue, or epoxy and held down
with strips of masking tape until dry.
Control Rods
Two interesting ways of doing control
rods came up during this build. Most
of us have either used a nut on one end
to prevent rotation in the clevis, or CA
hardened with kicker. Both are prone
to coming loose, and a nut can require
opening a pushrod slot more or changing
the position of the servo arm to prevent
banging or binding of the nut.
The fi rst method was suggested by
Modellbau. The provided pushrods are
Left: The left side of the fuselage shows the
easily installed and accessed dual switch gyro
and receiver, around the factory-installed plate.
The universal air trap (UAT) is easily accessed
when mounted to the front bulkhead.
Below: The engine hatch tended to collapse
inward because it lacked front and rear support.
The author epoxied 1/32 plywood strips to the
inside of the hatch opening to add support.www.ModelAviation.com March 2012 Model Aviation 71
Flying
Finally! If you read through the build
portion of this article, it was worth the
wait. I managed to fi nish in time to take
the F-86 to an event, but didn’t have
time to thoroughly go over everything.
After having two other sets of eyes
check linkages and movements, security
of surfaces and screws, balance and
retracts, we looked at throws. I checked
to see if I had a low rate programmed
into the radio and discovered I didn’t.
Two or three other issues were resolved,
but with everything triple-checked, I
nervously said, “Let’s go fl y.”
What a nonevent! That’s good on
a maiden fl ight. My fi rst three fl ights
were without the tanks, and the fi rst
takeoff was without the fl aps. A small
amount of up was needed since I was
slightly nose-heavy, and I added a bit of
aileron trim.
I was comfortable with the handling
and from the second fl ight on, low
passes were low and the full-speed range
was checked. I wished I’d had the full
45mm of fl ap defl ection, because the
aircraft wanted to continue fl oating
down the runway.
The next day, I added the drop tanks.
I had zero trim changes, and with the
power of the K-80 pushing, it is diffi cult
to guess if I needed to add one more
click of throttle.
The recommended settings for takeoff
fl ap work well, giving a smooth rotation.
Although it is recommended that the
fi rst fl ight be done without fl aps, I found
the rotation and departure easier and
more predictable with the fl aps.
I also found that a low rate of roughly
85% on ailerons gives a more scalelike
roll rate than the recommended setting.
Full fl aps, with the recommended
crow (also known as butterfl y or upailerons),
produced a stable, slow fl ight
regimen with a smooth fi nal approach
and complete aileron control all the
way to touchdown and rollout. The
recommended elevator trim was close.
Modellbau clearly did its homework.
Futaba GY 190 Gyro
This is the fi rst airplane in which I have
used a gyro. Modellbau recommends that
an inexpensive gyro, such as the GY 190,
be used on the rudder to counteract the
Dutch roll tendencies of many of the
early swept-wing fi ghters.
The company recommends a gain
setting of 25% as a starting point, which
produced some slight tail wag. Not
knowing if I had too much or too little
gain, I experimented with 35%, which
was way too much. I fi nally got it dialed
in at roughly 12%.
Several of the twin-boom fl iers at the
event routinely fl y their airplanes with
only threaded on one end; the idea is
to attach the supplied clevises to both
the servo arm and the control arm and
thread the pushrod onto one of them.
Mark the length to thread the smooth
end through the threads of the other
clevis and cut the pushrod. Thread the
smooth end forcibly into the clevis
and then solder that end together.
Adjustment is still available on the other
end and a jamb-nut is not needed.
In discussing this method with
several jet and large-model pilots, three
suggested using my favorite clevis (the
Sullivan Gold-N-Clevis) and 4-40 allthread,
but using J-B Weld instead of
soldering the end; this is what they had
been doing for years. (It was implied
that even I could mix two pastes
together and fi ll some threads.) This is
the method I used, but both work well.
The Modellbau demonstrator reportedly
made 250 fl ights without a problem.
Radio Needs
The F-86D requires 11 servos, plus
the throttle channel, so a nine-channel
radio system is the minimum radio
needed. To accomplish this, three
Equalizers or Match Boxes would be
needed for fl aps, elevators, and rudder/
nose gear. I don’t advise a fourth on
ailerons because the ability to activate
crow would be eliminated.
I used my Futaba 12Z transmitter
with a 6014HS, 14-channel receiver, 2.4
GHz radio system with Hitec servos.
The newer 12-channel radio systems
allow individual servos to be plugged
into the receiver and adjusted by the
transmitter’s internal functions. With
dual 6.6-volt Hobbico LiFe batteries
powering the onboard systems, there
are plenty of available electrons. This
ensures that the radio link is satisfi ed and
the servos have adequate power.
I’m happy to be able to fi ne-tune all
12 channels used with my transmitter.
Exponential is a subjective setting that
results in several arguments at the fi eld.
I typically only use 10-15% exponential,
and was using roughly 15-20% on both
the elevator and ailerons and did not
fi nd the model twitchy or soft. Just like
the gyro-gain setting, this needs to be
explored and fi ne-tuned.
The author
solved his
worries about
heat in the fi n
with a piece
of 3/32 balsa
covered with
aluminum
tape, then
epoxied
over the fi n
concavity.72 Model Aviation March 2012 www.ModelAviation.com
REVIEW
60-100% gain; however, I discovered
that a higher gain made the F-86 look
like a fi sh as it wiggled its way past me.
Conclusion
Modellbau has a winner! The F-86D
is a stable, enjoyable aircraft with a
huge fl ight envelope that looks great
and behaves well in the air. If you are
profi cient with a “full-house” warbirdtype
airplane, it could easily pull double
duty as a turbine-powered jet trainer as
well as a Scale airplane.
The trailing link struts from Spring
Air do not look out of place because
they remain straight under all but very
heavy landing loads. The wheels and
brakes work well, with consistent and
predictable braking action.
This airplane really is a two-thumbsup
purchase.
—Greg Moore
jetfl [email protected]
Charles Scarborough took this photo of the maiden fl ight at rotation. Takeoffs are far easier and more predictable using fl aps.
The painted pilot bust is in place on its ejection seat constructed from balsa
and fi berglass sheet.SourceS:
Modellbau uSA
(954) 224-1700
www.modellbauusa.
com
KingTech Turbines
(626) 793-4677
www.kingtechturbines.
com
Jetcat uSA
(805) 226-8700
www.jetcatusa.com
Spring Air Products
(321)728-9002
www.retracts.com
Jet Hangar Hobbies
(562) 467-0260
www.jethangar.com
McMaster-carr
(562) 462-4277
www.mcmaster.com
Micro Fasteners
(800) 892-6917
www.microfasteners.
com
Valley View rc
(253) 875-6890
www.valleyviewrc.com
Tower Hobbies
(800) 637-6050
www.towerhobbies.
com

www.ModelAviation.com March 2012 Model Aviation 65
The F-86 is one of the best known of the jet fi ghters and a participant in MiG
Alley during the Korean War. The aircraft starred in many movies and began
life as the straight-wing North American Aviation FJ-1 Fury. When that
version did not meet design criteria, among other changes, a 35° swept wing was
substituted, and in 1947 the YF-86 took to the skies.
With the fear of hordes of Soviet bombers attacking the US, work on a bomber
interceptor, the F-95A, began. The aircraft was renamed the F-86D and was wider
and longer, with a larger engine and a clamshell canopy. It was the fi rst Air Force
night fi ghter with a single engine and a single pilot.
The Sabre was only slightly similar to the other variants. It had a retractable tray
in the belly that held 24 2.75-inch Mighty Mouse Mk 4 Rockets instead of guns. It
was believed that the rockets would be more effective against a bomber formation,
especially at night.
Another variety was marketed as a NATO fi ghter. This model, known as the
F-86K, had the rocket tray replaced with four 20mm cannons. It was painted in a
number of color and camoufl age schemes.
Having had several versions of the venerable F-86, both electric-powered ductedfan
(EDF) models and glow-powered ducted-fan aircraft, I was thrilled to review this
release from ModellbauUSA.
I believe only two models of the F-86D have been produced—one many years ago
by Byron, and a propeller-jet version imported by Nitro Models. This version was
designed for turbine power, specifi cally the JetCat P60, with the focus on weight
management and simplicity.
Converting to EDF is as simple as replacing the stainless steel turbine tailpipe
with a Mylar tube and adding intake ducting. Adequate strength is needed to
accommodate the more powerful, heavier KingTech K-80 (which I used in this
review) and this has been designed in.
Is this a totally Scale, “let’s go to the Jet World Masters” aircraft? No. It is a Sport
Scale version of the most numerous variant of the Sabre. Scale fi delity in landing
gear placement is sacrifi ced for a wider and more stable confi guration, along with
slightly more wing area.
The model presents well in the air. This was taken shortly after liftoff. Charles Scarborough photo.
A turbine that’s
friendly to fi rsttime
jet pilots
Greg Moore
REVIEW MODELLBAU USA F-86D DOG SABRE jetfl [email protected]
Photos by the author unless noted66 Model Aviation March 2012 www.ModelAviation.com
If you are a Scale junkie, this airplane
is not for you; however, if you want
an attractive replica of a great-fl ying
airplane with a wide speed range and
fantastic ground handling added, this
might be for you.
The model is roughly the same
price as many of the larger ARFs in
the current Tower Hobbies catalog.
Modellbau has decided to sell the
aircraft, which is designed around the
15- to 20-pound thrust engines, in a
transportable size at a reasonable price.
Unpacking
The model is well-packed, but the
one I received suffered mild cracking
in the tail during shipping. It was easily
repaired, and is a testimony to the
correct strength and number of fi berglass
layers used in the layup.
The box includes a nicely fabricated
and painted fi berglass fuselage, sheeted
built-up wings, and tail feathers with
iron-on covering and stick-on decals.
Spring Air’s new, red, heavy-duty landing
gear is preinstalled. The package also
includes a prepainted, modern jet pilot
fi gure, lightweight, dual-walled tailpipe,
custom fi berglass fuel tanks, and all the
linkage hardware needed to assemble
the airplane.
You will need to purchase struts,
wheels, and brakes (I used the Spring
Air/Modellbau combination package),
as well as engine and radio components.
I used the KingTech K-80f, kero-start
engine, which I will discuss later.
Building the Dog Sabre
Because the instructions are
straightforward and available online
as a PDF, I will not give a step-by-step
review. Instead, I will assess items that
need clarifi cation, are interesting, or have
changed.
The fi rst topic is hinging all of the
control surfaces. You should be able
to open and check the contents of the
box, unpack everything, seal and shrink
the wrinkles in the covering, and hinge
your surfaces in one evening, or part of
a weekend day. The precut slots are that
well done.
Make sure you open/bevel the hinge
slots so the hinges are slightly recessed
to minimize the gaps. Lubricate your
hinge with some melted Vaseline, and
use a good, slow-setting epoxy such as
Hysol 9462 or E-20HP (available from
McMaster-Carr online, or your local
Fastenal store).
The only item of note in this part of
the assembly concerns the fl aps. The
SPECIFICATIONS
Type Sport Scale turbine jet
Skill level Intermediate builder;
intermediate pilot
Wingspan 60 inches
Wing area 895 square inches
Length 68 inches
Flying weight 15 pounds
engine 12- to 18-pound thrust turbine (or
large electric-powered ducted fan).
Recommended JetCat P60 or KingTech K-80
engines
Radio Nine-channel minimum with 11
servos
Construction Composite fuselage with builtup
sheeted wings and tail
Covering/fi nish Painted fi berglass fuselage,
iron-on covering on sheeted
parts
Street price $760
TEST-MODEL DETAILS
Engine KingTech K-80F
Radio system Futaba 12Z transmitter, Futaba
FASST 6014HS receiver, Futaba
GY 190 gyro
Ready-to-fl y 16 pounds, 2 ounces
weight
Flight duration 9 to 10 minutes
KINGTECH K-80F SPECIFICATIONS
Diameter 3¾ inches (95.25mm)
Length 10 inches (254mm) including
starter
Weight 2 pounds, 14 ounces (1304 g)
including starter
Maximum rpm 145,000
Thrust 19 pounds at 70° F
Idle 45,000 rpm
Exhaust 1202° F (650° C) maximum
temperature
Fuel 8.46 ounces per minute
consumption (239 grams per minute)
Maintenance 25 hours
cycle
Oil 5% Turbine oil
PLUSES
• Uses a wide range and selection of engine sizes.
• Gentle, predictable handling and performs well.
• Could be used as a fi rst jet.
• All included hardware is high quality.
MINUSES
• Landing gear too long for Scale appearance.
• Canopy could be constructed from clearer/
thicker material.
AT A GLANCE....
REVIEW
Everything needed to operate the engine is included with the exception of a battery pack.
Quality components are used throughout.www.ModelAviation.com March 2012 Model Aviation 67
incorrectly plug in the wires.
The rudder and elevator servos are
mounted inside the fin and stabilizers.
The rudder servo mounting is
straightforward. Add two hardwood
blocks to the hatch to fit the suggested
Hitec 5245MG servo, allowing the
control arm to center in the precut slot,
and then mount the hatch. The elevator
servos required more thought because
the stabilizers are so thin.
Modellbau recommends a thin-wing
servo with metal gears and at least 65
ounce-inches of torque for the elevators.
I used the JR Radios digital 378 thinwing
servo that meets the criteria.
It seemed to be designed to mount
against a hatch or surface, so I decided to
mount the servo to the hatch with four
4-40 machine screws through the four
mounting lugs. The rear set went all the
way through the double lugs, while the
front set had the lock, washer, and nut
between the lugs.
I cut a piece of ¼-inch aircraft-grade
plywood to fit snugly between the lugs
and fit against the front and rear spars,
trimmed them to the correct thickness
to allow the hatch to fit flush with the
bottom skin, and then epoxied them
into place using the hatch/servo to
position things.
Spring Air’s Red Jet series of
retracts are included in the kit
and feature larger cylinders and
springs to handle higher speeds.
The optional trailing link struts
look nice and function well.
precut and beveled flaps are hinged in
the middle of the surface, which allows
only 35mm of flap deflection. This is
perfect for a small engine such as the
JetCat P60, but can’t generate the 45mm
of deflection needed for a larger engine.
If you plan to use a KingTech K-80,
JetCat P70, Wren 70, or Super Sport,
the bevel in the flap should be filled
with a ¼-inch balsa strip and then
hinged at the bottom. My model could
have benefitted from the full 45mm of
flap deflection.
Keeping things as simple as possible,
Modellbau designed the aircraft to have
the servos outside of the wing; just
harden the holes with some thin CA and
screw them in.
The recommended servo for both
ailerons and flaps is the Hitec 645MG,
but since I still have 12 new 605s, I used
these. Control horn placement is as easy
as cutting a slot, setting the horn with
Hysol E20HP, and letting it cure.
I like to protect my wiring connections
from myself. With two servo leads to
the wings, and because I have managed
to connect the wrong pair in the past,
I eliminated that problem by using a
six-pin Multiplex connector. With each
extension wired to it, it’s impossible to
The well-protected contents include everything but glue, electronics, and an engine.68 Model Aviation March 2012 www.ModelAviation.com
I would have liked to move the engine
farther forward to help with balancing,
but the 1/2-inch gap I needed between
the engine and pipe dictated the fi nal
engine position. It is a good idea to fi t the
pipe-support mount and secure it with
epoxy mixed with fi berglass millings.
My next step was fi guring out where
I could neatly place everything that
needed to go into the fuselage—as
far forward as possible for balancing
purposes. I made a 1/8-inch plywood
REVIEW
Servo wires running to the
elevators and rudder pass close
to the tail pipe, so cover them
with aluminum heating-duct
tape or a heat shield.
The author slightly
scalloped the exit
opening on the bottom
to allow the stainless
steel pipe to exit the
fuselage.
When the engine mounting rails are correctly trimmed, the engine fi ts
evenly within them.
The elevator/servo openings are shallow, requiring a thin-wing servo and
creativity in mounting. Greg fabricated 1/4-inch plywood plates that fi t
snugly within the servo mounting lugs.
ended up with a scallop to allow the
pipe to exit.
Before installing the pipe supports, run
the servo wires to the rear and protect
them with aluminum tape or heat shield.
With the servo leads secure, the engine
can be fi tted through the bottom hatch
and onto the rails. The rails are narrow
enough for a P60 without needing to
add material. With the wider K-80, all I
had to do was remove a small amount of
wood to set the engine in place.
When dry, the hatch was screwed
to the ¼-inch plywood mounts with
servo screws from Micro Fasteners,
and the control horn was placed as
described earlier.
Now is a good time to open the rear
of the fuselage enough to allow the tail
pipe to exit. The hole is only a rough
opening, allowing those using their
pipe of choice to get the correct fi t. I
found that 90% of the trimming
I needed was on the bottom, andplate that screwed into some ¼-inch
plywood blocks with servo screws on
the right side, and used the already
installed mounting plates to mount
the Spring Air retract valve and dual
switch. Designed for large, gas-powered
engines, the switch is robust, has a small
mounting footprint, and snaps into on or
off position, as well as charge leads.
Likewise, I mounted the ECU to a
plywood plate epoxied to the bottom
of the fuselage. It’s easy to connect to
the ground-support unit and I like to
monitor the start information.
I use dual receiver packs with separate
switches into separate ports in the
receiver on my jets, so space was needed
for a pair of Hobbico LiFe 6.6-volt, 2100
mAh packs and the provided 9.9-volt
A123-LiFe pump pack in a secure spot
that was as far forward as possible.
The receiver packs can be mounted
with Velcro alongside the nose gear rails,
and the pump pack can be mounted
along with the retract air tank above the
inlet in the radome. It’s diffi cult to place
these heavier objects any farther forward.
This large space becomes small
quickly, and it gets even smaller when
you assemble the fuel tanks. I had to
open the existing hole in the bulkhead
to allow the fuel tank cap and lines to
come through smoothly. I trimmed
roughly 3/8 inch from the fl ange on top
of the fuselage to allow the tanks to
enter easily.
A thin piece of plywood was needed
beneath the inside edge of the tanks
so they would fi t fl ush with the sides
of the fuselage. Goop, PFM, or other
silicone adhesive between the tanks
and sides will keep the tanks in place.
With two tubular spars running through
the fuselage, it is important that the
servo leads and fuel and air lines are
secured to the fuselage with keepers or
attachments.
The Spring Air struts were mounted
into their retract units, given some
toe-in, then slowly retracted to avoid
smashing into the top skin. I had to
remove some of the wing rib, and shim
the landing gear to prevent it from
wedging against the top of the wing.
When I was happy with the fi t, I
made wheel well inserts to keep large
masses of air out of the wing. A hint Ifound online suggested I use an empty
cereal box, trimmed to shape, and
use my favorite Bob Smith Industries
medium CA to secure it in place. A coat
of thinned epoxy gave it fuel and water
protection and I was done.
To secure the wings to the fuselage,
carefully measure then drill a hole for
a ¼-20 bolt. If you have small hands,
a thumbscrew could be used to attachthe wing. I had to insert a carriage bolt
that I cut the head off of into the
blind nut in the wing and secure it
with blue threadlocker. This bolt goes
into the fuselage and through a ¼-inch
wheel collar that is secured within a
plywood block and epoxied to the side
of the fuselage.
An 8-32 bolt is substituted for the
setscrew and a fl at slot is cut into the70 Model Aviation March 2012 www.ModelAviation.com
I made a small shield from a scrap
of 3/32 balsa and covered one side with
aluminum tape. This was epoxied over
the top of the fi n support and hollow area
of the fi n base to provide insulation to
the elevator spars, rudder servo, and wires,
because I prefer the extra protection.
The instructions for installing the
canopy base are straightforward, but I
found that I needed to grind some epoxy/
fi ller to get the provided hatch latch as far
back as possible. When epoxied in place,
it provided a positive and secure fi t.
Because this is a classic jet, I couldn’t
bring myself to leave the cockpit empty
or use a modern pilot, so I ordered a
1950s Saber Jock pilot bust from Jet
Hangar Hobbies.
Two evenings with good old Testors
model paints made me feel like a 12-yearold
again. I created a fast, scrap-wood
carriage bolt to allow both a gripping
action on the bottom, and a safety
edge/slot against the bolt loosening.
Additional wing stability is achieved
with a 6mm carbon-fi ber antirotation
dowel placed at the rear of the wing.
The wings aren’t complete without
the drop tanks and I chose to do
the modifi cation as described in the
instructions.
The engine access hatch is supported
and secured on both sides with a
plywood frame, but nothing in front or
behind. When I fi rst assembled the hatch,
it looked fi ne, until I took the airplane
out of my cool basement and into the
summer heat where it sagged.
A quick modifi cation with two strips
of 1/32 plywood provides support, and a
small square of 1/16 or 1/8 plywood in the
middle of the strips provides additional
grip for a retentive screw.
Now is a good time to install the tail
feathers. Both the stabilizer and the fi n
bases on the fuselage and surfaces need
to be roughened with coarse sandpaper
and small divots, to give “tooth” to the
epoxy. A strip of blue delicate surface
masking tape around the edges allows
easy cleanup of excess epoxy, and Hysol
9462 provides long-lasting strength.
Modellbau instructs that the incidence
of the stabilizers must not be changed.
The incidence obtained through the
drilled holes worked perfectly, and it’s
nice to see that the fl ight characteristics
were perfected prior to the model
hitting the market.
REVIEW
ejection seat and cockpit, and painted and
epoxied them in place. Given the shallow
space to work within the cockpit tray, I’m
happy with the way it turned out.
The canopy can be secured to the
base (while on the fuselage) with Goop,
canopy glue, or epoxy and held down
with strips of masking tape until dry.
Control Rods
Two interesting ways of doing control
rods came up during this build. Most
of us have either used a nut on one end
to prevent rotation in the clevis, or CA
hardened with kicker. Both are prone
to coming loose, and a nut can require
opening a pushrod slot more or changing
the position of the servo arm to prevent
banging or binding of the nut.
The fi rst method was suggested by
Modellbau. The provided pushrods are
Left: The left side of the fuselage shows the
easily installed and accessed dual switch gyro
and receiver, around the factory-installed plate.
The universal air trap (UAT) is easily accessed
when mounted to the front bulkhead.
Below: The engine hatch tended to collapse
inward because it lacked front and rear support.
The author epoxied 1/32 plywood strips to the
inside of the hatch opening to add support.www.ModelAviation.com March 2012 Model Aviation 71
Flying
Finally! If you read through the build
portion of this article, it was worth the
wait. I managed to fi nish in time to take
the F-86 to an event, but didn’t have
time to thoroughly go over everything.
After having two other sets of eyes
check linkages and movements, security
of surfaces and screws, balance and
retracts, we looked at throws. I checked
to see if I had a low rate programmed
into the radio and discovered I didn’t.
Two or three other issues were resolved,
but with everything triple-checked, I
nervously said, “Let’s go fl y.”
What a nonevent! That’s good on
a maiden fl ight. My fi rst three fl ights
were without the tanks, and the fi rst
takeoff was without the fl aps. A small
amount of up was needed since I was
slightly nose-heavy, and I added a bit of
aileron trim.
I was comfortable with the handling
and from the second fl ight on, low
passes were low and the full-speed range
was checked. I wished I’d had the full
45mm of fl ap defl ection, because the
aircraft wanted to continue fl oating
down the runway.
The next day, I added the drop tanks.
I had zero trim changes, and with the
power of the K-80 pushing, it is diffi cult
to guess if I needed to add one more
click of throttle.
The recommended settings for takeoff
fl ap work well, giving a smooth rotation.
Although it is recommended that the
fi rst fl ight be done without fl aps, I found
the rotation and departure easier and
more predictable with the fl aps.
I also found that a low rate of roughly
85% on ailerons gives a more scalelike
roll rate than the recommended setting.
Full fl aps, with the recommended
crow (also known as butterfl y or upailerons),
produced a stable, slow fl ight
regimen with a smooth fi nal approach
and complete aileron control all the
way to touchdown and rollout. The
recommended elevator trim was close.
Modellbau clearly did its homework.
Futaba GY 190 Gyro
This is the fi rst airplane in which I have
used a gyro. Modellbau recommends that
an inexpensive gyro, such as the GY 190,
be used on the rudder to counteract the
Dutch roll tendencies of many of the
early swept-wing fi ghters.
The company recommends a gain
setting of 25% as a starting point, which
produced some slight tail wag. Not
knowing if I had too much or too little
gain, I experimented with 35%, which
was way too much. I fi nally got it dialed
in at roughly 12%.
Several of the twin-boom fl iers at the
event routinely fl y their airplanes with
only threaded on one end; the idea is
to attach the supplied clevises to both
the servo arm and the control arm and
thread the pushrod onto one of them.
Mark the length to thread the smooth
end through the threads of the other
clevis and cut the pushrod. Thread the
smooth end forcibly into the clevis
and then solder that end together.
Adjustment is still available on the other
end and a jamb-nut is not needed.
In discussing this method with
several jet and large-model pilots, three
suggested using my favorite clevis (the
Sullivan Gold-N-Clevis) and 4-40 allthread,
but using J-B Weld instead of
soldering the end; this is what they had
been doing for years. (It was implied
that even I could mix two pastes
together and fi ll some threads.) This is
the method I used, but both work well.
The Modellbau demonstrator reportedly
made 250 fl ights without a problem.
Radio Needs
The F-86D requires 11 servos, plus
the throttle channel, so a nine-channel
radio system is the minimum radio
needed. To accomplish this, three
Equalizers or Match Boxes would be
needed for fl aps, elevators, and rudder/
nose gear. I don’t advise a fourth on
ailerons because the ability to activate
crow would be eliminated.
I used my Futaba 12Z transmitter
with a 6014HS, 14-channel receiver, 2.4
GHz radio system with Hitec servos.
The newer 12-channel radio systems
allow individual servos to be plugged
into the receiver and adjusted by the
transmitter’s internal functions. With
dual 6.6-volt Hobbico LiFe batteries
powering the onboard systems, there
are plenty of available electrons. This
ensures that the radio link is satisfi ed and
the servos have adequate power.
I’m happy to be able to fi ne-tune all
12 channels used with my transmitter.
Exponential is a subjective setting that
results in several arguments at the fi eld.
I typically only use 10-15% exponential,
and was using roughly 15-20% on both
the elevator and ailerons and did not
fi nd the model twitchy or soft. Just like
the gyro-gain setting, this needs to be
explored and fi ne-tuned.
The author
solved his
worries about
heat in the fi n
with a piece
of 3/32 balsa
covered with
aluminum
tape, then
epoxied
over the fi n
concavity.72 Model Aviation March 2012 www.ModelAviation.com
REVIEW
60-100% gain; however, I discovered
that a higher gain made the F-86 look
like a fi sh as it wiggled its way past me.
Conclusion
Modellbau has a winner! The F-86D
is a stable, enjoyable aircraft with a
huge fl ight envelope that looks great
and behaves well in the air. If you are
profi cient with a “full-house” warbirdtype
airplane, it could easily pull double
duty as a turbine-powered jet trainer as
well as a Scale airplane.
The trailing link struts from Spring
Air do not look out of place because
they remain straight under all but very
heavy landing loads. The wheels and
brakes work well, with consistent and
predictable braking action.
This airplane really is a two-thumbsup
purchase.
—Greg Moore
jetfl [email protected]
Charles Scarborough took this photo of the maiden fl ight at rotation. Takeoffs are far easier and more predictable using fl aps.
The painted pilot bust is in place on its ejection seat constructed from balsa
and fi berglass sheet.SourceS:
Modellbau uSA
(954) 224-1700
www.modellbauusa.
com
KingTech Turbines
(626) 793-4677
www.kingtechturbines.
com
Jetcat uSA
(805) 226-8700
www.jetcatusa.com
Spring Air Products
(321)728-9002
www.retracts.com
Jet Hangar Hobbies
(562) 467-0260
www.jethangar.com
McMaster-carr
(562) 462-4277
www.mcmaster.com
Micro Fasteners
(800) 892-6917
www.microfasteners.
com
Valley View rc
(253) 875-6890
www.valleyviewrc.com
Tower Hobbies
(800) 637-6050
www.towerhobbies.
com