60 MODEL AVIATION
BY ANDREW JESKY
Plane Talk: Quique’s Aircraft Company 86” Yak 54
An already potent Scale
Aerobatics ARF aircraft gets
a pile of upgrades
This new Yak has been improved in almost every aspect, which translates to its excellent flight performance.
I WILL TOUCH on the basics of putting this
new 86-inch Yak together, but I will get indepth
about flying it.
Thank you to AMA and Quique’s Aircraft
Company for allowing me to do this review. It
is a great honor to be selected to evaluate one
of the most anticipated models to come out.
The 86-inch Yak is based on Quique’s
120-inch Yak that revolutionized the RC
world when he brought it out at the 2003
Tournament of Champions (TOC). At that
time many people were flying models such as
Extra 300Ls, Extra 260s, and Giles 202s, and
the kit manufacturers were designing and
kitting them.
It seems as though the Yak-54 has brought
new life to the market in the past five
years. You almost cannot go to a
manufacturer’s Web site
without seeing one of those
or the single-seat version:
the Yak-55.
Many are intrigued by the
design because the motor’s thrustline is
centered on the firewall, which gives the
airplane an appearance that it is rolling around
the spinner. That coupled with the round,
cylinderlike nose emphasizes it even more.
Another benefit is the model’s midwing
design. That allows for minimal roll coupling,
and the stabilizer’s being in-line with the wing
packaged. It came in one big box, but all the
parts were individually bagged with bubble
wrap around everything.
I also received the accessory pack from the
company. This hardware package contained
the wheels, axles, and wheel collars. That
indicated to me that the model came well
equipped and did not need many accessories
for completion.
The UltraCote-covered aircraft was
finished in a nice, colorful scheme Quique
uses on his Pitts Python and Brio RC
Aerobatics (Pattern) airplanes.
With everything done, it was
time to start building.
The first thing I did when
the airplane was out of the box was
hinge everything. All the hinge slots had been
cut. All that was left to do was slice back the
covering and insert all the hinges. Cutting the
UltraCote was easy with a #11 blade.
After all the covering had been removed
for hinging, I slid the hinges in to trial-fit
everything and make sure I would get
sufficient throws. When trial-fitting all the
surfaces I was able to get 45° of throw with no
problems. It was on to hinging.
I hinge all my airplanes with Gorilla Glue.
Urethane-based adhesive expands when
drying. I pour the glue into a small cup and
then apply it in the slots with a small-scale
helps with pitch coupling for knife edge. Now
that you know a bit about the Yak, let’s get to
building.
Construction: The first thing I noticed when
I opened the box containing the 86-inch Yak
was how nicely all the components were
Notice how
there’s very
little aileron
input to hold a
h i g h - a l p h a
approach.
07sig2.QXD 5/23/07 11:59 AM Page 60
Avoid handling the model around the wing sockets. The balsa
lining is exceptionally fragile.
The propeller sits ahead of the cowl to
improve efficiency. The Tru-Turn
spinner was removed to make the CG.
Photos by the author and Michael Ramsey
Wing bags are included with every kit; it’s a nice touch. The
film covering is real UltraCote.
Clear acrylic side force generators attach with 4-40 hardware.
They are an asset at slow speeds and rolling maneuvers.
Strong construction permits the
use of just one 200 inch-ounce
servo for each surface.
ruler. Make sure not to use too much glue; it will
expand back into the hinge and cause friction.
If you have never used the glue, it
is a good idea to get a block of
wood and try a few different
amounts before hinging the
airplane. With Gorilla Glue
all the surfaces can be
hinged at once; it takes the
adhesive roughly 12 hours
to dry.
When
everything
was hinged I
left the model to sit
out for approximately
two days, to let all the
humidity get out of its
wood. I do this with most ARFs because
the humidity is so high in China that the
models need time to dry out when they arrive in
the states.
When I came back to the Yak I saw that the covering
had gotten some wrinkles in it. I
went over it with a heat gun and
iron, as described in the
instructions.
After shrinking the covering
back down I installed the landing
gear and tail wheel. That way the
airplane was on its own base
while I was working
on it and
would not get
banged up on the
bottom of the
fuselage.
The landing gear installed easily
with the holes predrilled in the gear
and fuselage. All that was left to do was
run the screws in from the top and put lock
nuts on the bottom of the fuselage.
July 2007 61
07sig2.QXD 5/23/07 12:02 PM Page 61
62 MODEL AVIATION
Above: The airframe
is lightened by filling
cutouts in the lightplywood
frame with
balsa substitutes in a
cross-grain pattern.
Right: A Du-Bro 18-
ounce fuel tank is
more than enough
for a 15-minute
flight. Velcro straps
neaten the wiring.
Right inset: The allin-
one PowerBox
battery includes a
2800 mAh, 7.4-volt
Li-Poly battery and
charger, supplied
with a regulated
switch.
A single Futaba S9155 servo is plenty of power for the large
rudder. The carbon-fiber yoke is supplied.
As with the ailerons, the elevator hardware is titanium with
oversized ball links. Two 4-40 screws secure the stabilizer half. The tail wheel was also easy to install since there were blind nuts
in the back of the tail for the tail wheel to attach to the fuselage. It
might make it easier to work on the airplane if you do not put the
wheels on the landing gear; if you do it will then want to roll.
With the landing gear and tail wheel on, it was on to mounting
the engine. A nice thing about this model was that the hole was
already located for the 3W-50 and the DA-50. On this model I
was planning on using the DA-50 with an MTW canister for a
quieter sound.
The 3W and DA engines use a rear-induction carburetor, and
there were lines laser-marked on the firewall indicating where to
cut depending on the engine chosen. After I drilled the holes for a
1/4-20 on the firewall, I cut the firewall with a Dremel tool and a
cutting wheel.
07sig2.QXD 5/23/07 12:06 PM Page 62
Engine used: Desert Aircraft DA-50-R
with MTW 75 canister
Propeller: NX 23 x 8
Fuel: 22-ounce tank, 50:1 gas/oil mix
Radio system: Futaba 14MZ
transmitter; Futaba R5014DPS receiver;
seven Futaba S9155 servos; PowerBox
7.4-volt, 2800 mAh battery system; eight
servo extensions; two power switches
Ready-to-fly weight: 16 pounds, 6
ounces
Flight duration: Exceeds 10 minutes
Test-Model Details
+
• High-quality, well-constructed kit.
• Flies great with little mixing.
• Included wing and stabilizer bags.
• Excellent linkage hardware.
• Preinstalled exhaust canister mount
(meets AMA noise regulations).
• Easy 3W or DA 50cc engine
installation.
-
• Hard landings flex landing gear, causing
the paint to fracture.
Pluses and Minuses
Type: RC Scale Aerobatics, 3-D
Pilot skill level: Advanced
Wingspan: 86 inches
Wing area: 1,420 square inches
Length: 75 inches
Weight: 15.5-17.0 pounds
Wing loading: 25.215 ounces/square inch
Engine: 50cc-60cc two-stroke (gas)
Radio: Six channels (minimum), seven
servos
Construction: Light plywood; balsa
wood; tinted canopy; fiberglass cowl and
wheel pants; fiber-glass composite landing
gear, wing tube, and stabilizer tubes
Covering/finish: Four-color Hangar 9
UltraCote
Price: $649.95 plus shipping and handling
Specifications
The firewall has been etched to note the
cutouts required for either a DA or 3W
rear-carbureted 50cc engine.
Right: The DA 50cc engine has been
installed with the MTW canister muffler
system. The package drops right in.
The throttle and choke servos mount
directly in line with the linkage. Notice
the fitted cowl supports midbox.
The Yak is neutral; little to no mixing is required. The tinted canopy helps define
the outline of the aircraft.
July 2007 63
07sig2.QXD 5/23/07 12:07 PM Page 63
When I got close to the lines I went in with
a sanding drum, cleaned up the cuts, and got
into the corners I was unable to reach with the
cutoff wheel. With all that cut, I bolted the
engine to the firewall to make sure the
alignment was right. After verifying this, it
was time to mount the header and canister.
I had to cut 8mm off the header so it
would be the correct length for the Yak. Then
I slid the header onto the can with the Teflon
coupler. This job was simple since the can
mounts were already in the airplane. I slid the
MTW can onto the mount and cut the
covering back so the can could let its heat out
the bottom of the model.
At this point I was ready for the final
installation of the engine and canister. I used
Loctite on the mounting screws to the engine
and installed the header/canister combo using
a red RTV (room-temperature vulcanizing)
silicone.
This model was set up for a choke servo
because it is extremely hard to access the
choke on the rear-induction carburetor. The
Yak came with a servo plate that was glued to
the engine box when the servos were installed.
Setting up the throttle and choke was easy
to do with 4-40 rods and ball links. One
important thing to remember when setting up
the throttle is that it is best to have the travel
adjustment/ATV (adjustable travel volume) as
close to the same number as possible on the
high and low ends.
On this model I have zero subtrim and my
ATV is set as such: 120 on the low and 120
on the high. This allows for the best resolution
of the servo and the most linear throttle.
After that I installed the fuel tank, ignition,
and ignition battery. It all went smoothly;
those components were a cinch to mount.
The cowl was slightly tricky to get cut out
for the engine. When I was getting ready to
cut this I had to do some measurements to
make sure the cowl would fit the engine well
and that I would not have to cut a huge hole
for it to fit. After spending time rough-cutting
the openings with a cutting wheel, I cleaned
up the edges with the sanding drum.
The instructions gave all the dimensions
necessary to mount the cowl and tell how far
everything should have been spaced and
drilled. When all the bolts were drilled and the
blind nuts were mounted, the cowl was ready
for final installation.
Some useful information I learned from
my good friend Larry Markey is that when
putting the cowl on it is good to use a silicone
under the cowl where it meets the fuselage.
This creates a bond to the fuselage for a little
more support and will not make the holes in
the cowl oblong if the screws loosen.
Installing the servos in the wing was
straightforward. I cut the covering away and
installed the servo pockets that were already
in the wing. I used Futaba 9155s, which are
rated at 195 ounces of torque at .13 transit
time.
The control horns are a G10, more
commonly known as fiberglass. They
comprise three parts: two sidepieces and a
baseplate. I installed these control horns with
Gorilla Glue so the adhesive would expand
and make a good bond to the wing. I waited
overnight for these to dry.
When the glue in the control horns dried, I
installed the servo arms and control rods. I
used Futaba’s 1.5-inch aluminum servo horns,
which are nicely made and extraordinarily
lightweight. The control rods came with the
kit and were a titanium turnbuckle that
allowed for easy adjustment. The kit also
came with the ball links needed to finish the
model.
It took approximately 10 minutes per wing
to get the control rods hooked to the wing and
functioning. After both wings were done I
sealed the hinges.
Larry Markey showed me a great idea for
sealing the hinge line. If you have ever tried to
seal hinges with regular covering, you know
how hard it can be. He had been using clear,
flexible 3M Blenderm tape, which we use for
hinging foamies. This takes all the problems
out of sealing the gaps.
The Yak’s wing is held on by two body
pins that are commonly used in RC cars.
These pins are held against a wing with a
washer and rubber O-ring to keep a good,
snug fit.
It is critical to get these pins in the correct
location; if they are too far out, there will be
slop in the wing saddle. Conversely, if there is
not enough sticking out, the wing cannot be
secured. Therefore, I followed the instructions
carefully and got the pins aligned just right.
I mixed a batch of 30-minute epoxy
with microballons and made a nice fillet
around the pins where they attached to the
ribs. Before the final gluing it was
important to rough up the aluminum rods to
give the glue something to stick to.
After that I found the two holes in the
ends of the wingtips for the side force
generators (SFGs) and opened them up.
The SFGs were already drilled and the
blind nuts were in the ends of the wings. I
simply bolted them on when they were
ready.
I inserted the stabilizer servos into the
root of the stabilizer with just the servo arm
sticking out the bottom. I cut away the
covering to allow for the control horn.
When installing the servos it was easier to
put the servo arms on before the servos
were installed in the stabilizer. Again I
went with the Futaba 9155 servo and 1.5-
inch Futaba control arm.
After the servos were installed I
followed the same process as with the wing.
That was to install the control horn (which
was the same as the wing’s), hook up the
control rod, and seal the gaps.
The antirotation pin in the stabilizer is
just a piece of 4mm carbon rod that was
glued into the stabilizer the same way the
ones were in the wing. I did round the
carbon so that when it fits into the fuselage
it will slide a bit easier.
The rest of the project was the fuselage.
I cut back all the covering that needed to be
relieved, which consisted of the wing
saddle, stabilizer cutouts, and rudder-cable
exits.
The only tricky part was the wing
saddle. It was made from 2mm balsa, and I
had to roll the covering over onto the saddle
so it would not come loose. I did this by
cutting the covering but leaving
approximately 3/8 inch around the edge, and
then I put a couple cuts in the covering so it
would blend around the wing shape.
For the pull-pull rudder setup, the first
thing to do was install the control horn in
the rudder. This control horn was the same
as in the wings except it was a double-arm
type. I used Gorilla Glue as before with the
other controls.
The main thing when setting this up was
to make sure the holes for the ball links
were in-line and exactly 90° to the hinge
line. If this control horn were set up
incorrectly the pull-pull wires would have
become slack when working because the
geometry would have been incorrect.
While the glue was drying I installed the
rudder servo in its spot in the fuselage. I
used the Futaba 9155 servo again.
The kit came with a great carbon-fiber
horn that had a 7° offset built into it so the
geometry would work correctly. I installed
the carbon horn to a Futaba 20mm double
arm by drilling and tapping the horn with 4-
40 threads.
I finished the rudder by hooking up the
pull-pull cables. I used the supplied
hardware for setting this up. I did only one
extra step when getting these ready, which
was to install a plastic rod over one of the
cables. They were crossed and I did not
want them to rub on each other.
The fuselage had a nice cutout for a
standard switch in the fuselage, but I
decided to use a PowerBox Digi-Switch. It
has a built-in regulator and a fail-safe,
meaning it will turn on if it goes bad and
not turn off.
I went with a PowerBox 2800 mAh Li-
Poly main battery pack. I have used these
batteries before in my 40% airplanes and
really like them. They seem to be able to
hold their voltage better than any Li-Ionstyle
battery I have tried.
The batteries come in a strong holder
that is mounted with servo screws and
grommets. The battery pack itself has a
built-in charger and simply requires a 12-
volt power supply for charging. Once the
battery is connected to the Digi-Switch and
plugged into the receiver, it’s ready for use.
I used the Futaba G3 receiver and
installed it where the manual
recommended. I put a piece of masking
tape on the bottom of the receiver and then
glued it to the protective foam. It works
well and is a great vibration dampener.
I ran the extensions that were needed to
finish the Yak and mounted the wheels and
wheel pants. This job went quickly since
the wheels, axles, and wheel collars came
with Quique’s accessory pack.
I just put the wheels on the axles and
mounted the wheel pants with two 4-40
screws and blind nuts into the wood that
was already glued to the wheel pants. The
only thing to do was make sure the two
wheel pants were lined up parallel to each
other.
With everything installed, all that was
left was to put the propeller and spinner on.
I went with the NX 23 x 8 wood propeller
for break-in and a 4-inch P-51 Tru-Turn
spinner cut for this model. When those
were on, I balanced the Yak but it came out
slightly nose-heavy. I flew the initial test
flights without the spinner.
The model’s weight came out to 16
pounds, 6 ounces—a terrific weight for a
DA-50-powered airplane. The last thing to
do was set up the model on my 14MZ
transmitter. I followed the recommended
setting for the initial flight.
The Fun Begins: I met up with MA
Associate Editor Michael Ramsey at the
Celina, Ohio, flying field for the test flight.
A few nights before that I ran the engine to
break it in a little bit. It started on roughly
the fourth flip and ran like a champ. The 23
x 8 propeller was turning at 6,700 rpm on
the ground.
This was running extremely rich to
break in the engine, so when it comes time
to lean it out I’ll bet there are a few hundred
more rpm to be gained. With the engine
running I did a range check and everything
tested great. For the first test flight I went
ahead and put the SFGs on the airplane.
The takeoff went great and the Yak took
This confirmed my conclusion that the
model was a bit nose-heavy. I made a few
passes to check the trims, followed by many
roll combinations and different loop
combinations to make sure everything was
straight.
I did some Snap Rolls to see how the
model performed. Then I did a bit of 3-D
with it. After roughly five minutes I landed
the airplane to make sure all the bolts were
still there; they were.
After the postflight check I fueled up
again to go for another flight, to get some
more time on the Yak. After this flight I
could tell more about the airplane. I noticed
that it had a bigger feel to it. It seemed to
present well in precision maneuvers.
In knife edge the airplane took
approximately 5% knife-edge mixing to get
it flying straight down the runway. I think
that will change when I move the CG
slightly farther back.
With the knife edge mixed out I wanted
to test the SFGs. I performed many Rolling
Circles and Rolling Loops, which showed
that with the SFGs on the model it took
much less rudder than normal to help pull
it around the corners when rudder was
applied.
I tried some knife-edge loops. The Yak
did them well but exhibited some knife-edge
mix when at the bottom of the loop. This
could be taken care of with mixing on a
curve instead of a straight-line mix. After
messing around with the airplane’s RC
Aerobatics capabilities, which were
excellent, I went into all the 3-D maneuvers
I could think of.
The model performed everything great. I
thought at first that the ailerons were going
to be a bit slow since they were smaller than
what I’m used to in proportion to the wing.
I was wrong; when I put the Yak into
high rates and started to roll the model, it
did so rapidly. Even with the SFGs
installed, the roll rate was fast.
I decided to check the other surfaces for
authority. I took the model up and did some
flat spins, and boy were they flat! Even with
the CG a little far forward. They seemed to
get flat but were easy to get out of.
After that I did some knife-edge spins. I
always had a problem getting some
airplanes into the spin, but this one seemed
to go right into it. I was extremely
impressed with that.
With all that done a few times, to make
sure it wasn’t just beginner’s luck I tested
for Waterfalls. The airplane seemed to go
around tight, but I had to be quick on the
rudder; it would want to dish out if I did not
catch it on the way around. After that it was
on to hovering.
I put the Yak into a Harrier, where it was
stable, and I brought it down the runway
into the wind. When it was directly in front
of me I gave slightly more power, and it
pulled right into the Torque Roll. It seemed
stable in this maneuver, with no bad habits.
The airplane has more than enough
control authority to get out of any bad
situations when hovering. Just add the
correct control needed and a bit of power,
and it will be straight again.
If you’re wondering about power, the
pullout with the DA-50 is amazing. Even
with it running rich, it was like a rocket
going skyward.
The last thing for me to test was the
Rolling Harrier. This airplane, like all Yaks,
does these incredibly well. When you have
the ailerons set correctly with the right
amount of throw, the model appears to be
spinning around the cowl, which gives a
cool appearance when doing this maneuver.
This airplane is a winner. It was built very
nicely and flies fantastically. If you are
looking for a new 50cc airplane, you should
definitely consider Quique’s Aircraft
Company’s Yak. It flies like a much bigger
model.
This aircraft could be used in IMAC
(International Miniature Aerobatic Club) all
the way up to Advanced-class Aerobatics. It
will be my new Freestyle practice airplane
because it can be thrown around the sky
with no problems at all.
The only thing I have found wrong with
the Yak is that the composite landing gear
seemed stiff. While doing a Harrier landing
the paint on the landing gear actually
cracked off. It did not crack the gear—just
the paint; therefore, I think the gear tried to
flex but just chipped off the coating.
I am told that the OEM has been made
aware of this problem. Quique’s Aircraft
Co. thinks that perhaps the primer coat
surface was not cleaned properly or maybe
the primer coat should have some plasticizer
added for more flexibility. The landing gear
was not designed for Harrier landings. MA
Andrew Jesky
[email protected]
Manufacturer/Distributor:
Quique’s Aircraft Company
3410 Saint Paris Pike
Springfield OH 45504
(937) 629-0339
www.somenzini.com
Sources:
Radio equipment:
Futaba
www.futaba-rc.com
Battery:
PowerBox Systems
www.powerbox-systems.com
Engine, muffler:
Desert Aircraft
www.desertaircraft.com
Hardware accessories:
Du-Bro
www.dubro.com
Spinner:
Tru-Turn
www.tru-turn.com