color match between covered and painted parts.
fit could be better.
Great Planes Zlin Z-526 "Akrobat" is patterned after the full scale
version seen at airshows through the 1960's. Moravan Otrokovice of the
Czech Republic produced the "26-series" of aircraft beginning in 1946
with the original Z-26, progressing through the subject Z-526, and
finally culminating with the Z-726 in the 1970's.
its Z-526A Akrobat form, the Zlin's seating capacity is reduced from
two to one. It sports a bubble canopy, and a 160HP Walter Minor 6-III
carburated six-cylinder engine rather than the long greenhouse cockpit
and 106HP Walter Minor 4 engine. At 24ft 4in long, and with a wingspan
of 33ft 9in, it is roughly the same size as another airshow performer
from the same era: Art Scholl's DeHavilland Super Chipmunk.
fact, the Zlin and Super Chipmunk are very comparable. Not only do they
both have the same aesthetic ?feel? to them, they were both created for
the same purpose, to thrill audiences at airshows. The Super Chipmunk
has about 100HP on the Zlin, but the Zlin is about 300lbs lighter. In
model form, I'd expect the Zlin to have very similar flying qualities
to a Super Chipmunk of the same size and weight. That is, fast and
aerobatic, capable of airshow-style aerobatics, pattern maneuvers, and
very smooth overall.
a full scale wingspan of 33 feet, 9 inches, and a model wingspan of 58
inches, Great Planes' rendition of the Z-526 is roughly 1/7 scale. It's
a perfect size for any .46-class 2-stroke glow, .70 4-stroke glow, or a
700+ Watt electric power system.
58 in (1470 mm)
Wing Area: 633 in² (40.9 dm²)
Weight: 6-6.75 lb (2695-3005 g)
Wing Loading: 22-24 oz/ft² (66-74 g/dm²)
Length: 52 in (1320 mm)
Requires: 4-5 channel radio w/4-5 servos; 2-stroke .46-.55 cu in
(7.5-9.0 cc) or 4-stroke .52-.70 cu in (8.5-11.5 cc) engine; OR
RimFire? 42-60-480kV outrunner brushless motor, 60A brushless ESC
& (2) 11.1V 3200mAh 20C
than the typical wrinkles in the covering, which you're going to get
with any ARF, the Zlin arrived in perfect condition. An extended engine
box and removable canopy/cockpit hatch allows you to see most of the
fuselage's structure. The fuselage is all interlocking plywood sheeted
with balsa. Pretty conventional. Out back, the fin is already
integrated into the fuselage structure, and the stabilizer slot has an
airfoil profile. Inside the cockpit
the most detailed instrument
seen in an ARF to date. The recessed instruments are a nice touch. Foam
core wings with an aluminum wing joiner and pre-hinged ailerons round
out the airframe.
the box is here... Time to get started. Let's see what's inside!
the Zlin is like peeling an onion. It doesn't make you cry, but it does
#2 is the fuselage and hardware. The hardware boxes do double-duty by
keeping the fuselage protected.
first part out of the box, and it looks like it's done already.
for dual power, the removable canopy opens to reveal a combination
battery tray and fuel tank cradle.
Zlin has a long nose so there's an extended engine box ahead of the
hatch is secured in two ways. First, it slides back and hooks. Second,
four rare earth magnets keep it there.
is a very convincing instrument panel.
OS .55AX 2-stroke glow
Futaba S3004 standard on control surfaces, Futaba S3003 on throttle
Futaba 8FGA FASST
Futaba R8000HS FASST
Accessories: Futaba and Hobbico
Great Planes (included with kit)
8FG 2.4GHz FASST SYSTEM
latest offering in the ever-competitive, high-end sport radio class is
the new 8FG. It's a fully-programmable, fully-proportional 8-channel
heir to Futaba's legendary lineup of deluxe sport radios including the
9C, 8U and 7U platforms.
The 8FG is a native 2.4GHz system. Its antenna is in the normal
location; there is no add-on module as in previous systems, so there is
no "extra" antenna to contend with. With the antenna folded, the 8FG
will fit in standard transmitter cases and balances perfectly on a neck
Completely new to the 8FG, and Futaba systems in general, is the
SensorTouch interface. Gone are the old-fashioned programming buttons
and dials. In their place is a single round touch pad that takes
surprisingly little pressure to activate. It takes a little getting
used to, but when you master it you feel like a Jedi knight as you wave
your index finger over the pad, programming your radio with barely a
Programming options are limitless. Any function or mix can be linked to
any of the eight switches, two sliders, or two dials. Up to 20 model
memories may be stored on the 8FG's internal memory, but model memories
are unlimited using common Secure Digital (SD) memory cards up to 2GB
Paired with the lightweight and compact 8-channel R6008HS receiver, the
new 8FG system makes a great step up into a high-end radio, or a great
way for owners of aging 72MHz systems to get into 2.4GHz, and give up
frequency conflicts, interference, and the pin board.
new 8FG in all its styrofoamy glory. Almost too pretty to remove from
the package, but I gotta if I want to use it.
R6008HS receiver provides an order of magnitude of protection over the
FM receivers it replaces. Plus, it's smaller and lighter.
squares burned into the aileron servo plates show you where to glue the
blocks if you're using Futaba
servos. While the epoxy was curing, I prepped the aileron servos and
installed the wheels on the landing gear.
Notice how the main gear legs come flat spots pre-ground on the axles
for the wheel collars. That's good for shaving about 30 minutes off the
typical assembly, since you don't have to assemble the gear, mark for
the flat spots, disassemble the gear and file the flat spots...
Since the epoxy on the aileron servo blocks was still the consistency
of used chewing gum, I skipped ahead test-fit the horizontal stab in
the fuselage. It slid right in, looked pretty square by eye, and was
easy to square up. The instructions have you measuring from the
wingtips to square up the stab, but since the wings aren't done yet, I
did it the old fashioned way.
flats on the landing gear axles.
laser etched squares locate the mounting blocks for Futaba Servos. You
may need to locate them differently for other brands.
kept myself busy by checking the tail alignment while the epoxy cured.
both sides and make sure they're equal. Triangulation ensures
a seasoned ARF assembler will be impressed at how well things go
together, not to mention how quickly: Prep the servos by installing the
shock mounts, trimming the extra arms off, and adding a 12" extension.
Use the pre-threaded string to snake the aileron extension through the
wing. Secure the hatches with four screws.
Install the control horns and pushrods. Epoxy three alignment dowels
into the wing halves. Add the landing gear.
Slide the wing halves on to the aluminum spar tube. Done.
Presumably because of the foam core construction and the possiblity of
thin CA wicking through to the foam core, the ailerons come pre-hinged.
I'm not complaining. CA hinges are easy enough to deal with, but if you
don't have to... What was that saying about "gift horses" and all?
It's always a good idea to secure the connection to the aileron
extension. I like using twist ties that come with garbage bags, because
they're quick and cheap. Simply thread them between the red and black
wire on one side, and the red and white wire on the other side. Twist,
and trim. That connection is not coming apart.
The aileron servo hatches are finally ready for installation. I coldn't
find my 5 minute epoxy so I had to use 2-hour...
This is how you "tie one on" building a radio controlled airplane.
Tying it like this ensures that the extension pulls smoothly.
Here's the leader line for pulling the servo extension through the wing.
Give it a tug...
The extension slides right through because you tied it properly...
...and the servo hatch almost falls into place.
All that's left are four screws to secure the hatch.
Marking the center point of the aileron horn.
There are hard points in the ailerons for attaching the horns. No
through-bolting necessary. Short linkage helps prevent flutter too.
wing half is complete, with landing gear and alignment dowels epoxied
in. I used 5 minute for the dowels...
the wing halves together on the aluminum wing tube. Wings can be left
two-piece or can be epoxied together. Your choice.
to attach to the fuselage.
next phase of construction is attaching the wing, aligning the stab,
and epoxying it in place. Having the wing in place not only stabilizes
the plane, it gives you two extra points of reference for squaring the
stab to the fin. Everything is airfoiled, so you can't really use a
square to align the stab and fin. You need to measure up from a level
work surface on each side. GP suggests that if the alignment is a
little off, use a weight on the high end of the stab. Mine was a mere
hair off, so I used a receiver pack to weigh down the high end. Moving
the weight in and out on the stab results in varying degrees of twist
on the stab to get the measurements just right. Once the epoxy set up,
the alignment was perfect with the battery pack at the outermost left
end of the stab.
major assemblies come together for the first time.
nuts are already installed in the fuselage. Wing holes are already
cleared of covering.
looks like an airplane now.
to epoxy the stab in place. A bottle of rubbing alcohol and paper
towels are on hand to clean up excess epoxy.
a receiver battery as a counterweight to get perfect alignment on the
stab. Still a hair off...
further out the battery is, the more twist it puts on the stab. Here
it's all but perfect.
has you gluing in the CA hinges for all the tail surfaces before
installing the control horns. At least in my experience, this is where
the lion's share of hangar rash occurrs because you're holding the
plane at odd angles, and pushing down on a screwdriver while tightening
the control horn screw.
How many +-shaped holes do you have in your planes from the screwdriver
If you can install the control horns BEFORE the hinging, it's a whole
lot easier, and you're less likely to ding up the plane. After sliding
the pushrods in for reference, I slipped the elevators and rudder in
place and marked the locations for the control horns. Back on the
stable pink-foam work surface, it was simple to drill two holes per
surface and install the control horns. As another anti-+-shaped hole
measure, I used #2 socket head servo screws from Micro Fasteners
in place of the included Phillips
headed screws to secure the control horns.
After I prepped the three control horns, it was a simple matter to
epoxy the tailwheel in place, slide the control surfaces back on, and
secure the CA hinges.
mocked up to locate the control horns.
shot of the left elevator pushrod.
a pin vise to mark the holes for the rudder control horn.
to the pushrod holds the control horn in place.
from the plane, it's much easier to install the horns.
through the plywood hardpoint at the marked locations.
the holes with a tiny drop of thin CA.
the horns using #2x7/16" socket head wood screws from Micro Fasteners.
three control surfaces ready for CA hinging.
right along, we come up on servo installation and the "controversial"
elevator pushrod joining. I say controversial because time and again
I've heard that joining pushrods by clamping them with wheel collars is
insecure. The pushrods will slip, and you'll lose elevator control.
With the Zlin's setup, there is very little to go wrong. One elevator
pushrod is a direct connection from the servo to an elevator half, so
even if the other half slips completely loose, control can still be
maintained. The heads on the set screws are oversized, so you can use a
large hex wrench and REALLY romp down on the pushrods and clamp them
tight. I tried seven ways from Sunday to make the rods slip, and I
could not do it.
marks the spot, where the two elevator pushrods cross is where you make
the left elevator pushrod at the mark so it runs parallel with the
trimmed and ready to join.
L-bend clips are my favorite way to secure pushrods on servos.
the screws to the pushrods. They are NOT coming loose.
it really that simple? I guess so!
for the power system. The fuel tank includes parts for a conventional
3-line system (fill, vent, carburetor), which is my favorite way to set
things up. While the instructions suggest 1/4" foam above and below the
tank, there isn't enough room for foam on top with the tank's neck
inserted into the hole in the firewall. Since the tank's a snug fit on
the sides, and sits tightly against the firewall, the foam on top
really wouldn't help much to isolate the tank from the fuselage.
Blind nuts are already installed in the firewall for the included Great
Planes engine mount. Attaching the 55AX engine is a matter of locating
the engine on the rails, drilling four holes, tapping for 6-32 screws,
and running them in.
Off camera, I test fit the cowl over the engine. There's plenty of
clearance for the head, something that you'd need to trim for with a
4-stroke. It looks like I'll only need to cut three holes, one for the
carburetor, one for the needle valve, and one for the muffler port.
The Zlin is designed for two-stroke, four-stroke, or electric power,
even down to the throttle pushrod routing. Four-stroke carburetors are
"backwards" compared to two-stroke carburetors. That is, the throttle
arms are on opposite sides of their respective engines. There are two
servo mounting locations, and two holes in the firewall for the
throttle pushrod tube to cover either internal combustion possibility.
Since I'm using the .55AX two-stroke engine, the servo and pushrod tube
ended up on the left side of the airframe. The hole in the firewall
positions the pushrod such that it makes a nice smooth curve from
carburetor, through the firewall, under the fuel tank,
and back up to the throttle servo with no bending required.
fuel tank pops in place, like the plane was designed around it. Oh
is the last time the engine will be upright, except during inverted
new engine... I had to get a closeup.
it's in its proper orientation.
options for 2- and 4-stroke engines.
pushrod with no bends required.
on the agenda is fitting the cowl. This is more of an art than a
science, and one that I'm still trying to perfect.
If you're not a fan of fitting cowls to engines, a 2-stroke engine will
be a better choice over a 4-stroke. There's plenty of clearance for the
head underneath the Zlin's tall narrow cowl, with only a slight bit of
interference at the carburetor. A couple of passes with a Dremel
sanding drum opens up the front to clear the carb and provide smooth
airflow to the intake.
Once the carburetor has been clearanced, the cowl will slide back into
its final resting place. Let me warn you right here: There is a lot of
installing and removing the cowl to get it to fit properly. Take your
time and only remove a little bit of material at a time. Your patience
will be rewarded.
The instructions describe a technique for fitting the cowl that uses a
strip of paper taped to the fuselage to locate the muffler hole. I've
used this technique for years. In fact I picked up the technique while
building another Great Planes
product almost a decade ago.
With four hardwood blocks already on the firewall to mount the cowl, I
wanted to make sure I hit them, so I used the paper strip technique
first to mount the cowl. First, I located and drilled 1/16" holes in
the exact center of each block. Next, I cut four 6"x3/4" strips of
printer paper. I taped one end of each strip to the fuselage such that
the free end of the strip covered my predrilled holes. Using my Higley
hand drill, I poked a hole in each strip to match the predrilled holes
in the blocks.
When you slip the cowl in place between the airframe and the free ends
of the strips, and lay the strips down flat on the cowl, you now have
the exact location of the screw
holes to mount the cowl! It's a simple matter of drilling the holes.
by predrilling holes in the cowl mounting blocks.
strips of paper to the fuselage to transfer the holes to the outside of
holes through the paper at the predrilled holes.
the spinner to locate the front ring of the cowl.
the strip of paper over the cowl and drill through the fiberglass.
screws as you go and the cowl ends up mounted at the end.
the cowl is located on the airframe, it's time to make the rest of the
holes. In this case, the total number of holes required appears to be
1. A hole for the muffler.
2. A hole for the glow igniter.
3. A hole for the main needle valve.
That muffler hole is the most complicated one to deal with, so I
started there. The same basic paper technique is used to locate all the
holes in some way shape or form. In the case of the muffler hole I used
the paper and pieces of cutoff pushrod to mark the two muffler bolt
holes. After transferring those marks to the cowl, and drilling the
holes, I literally bolted the muffler to the cowl and traced the flange
with a marker to get an idea of how large the hole needed to be. Over
several fittings, the muffler hole slowly took shape, by removing small
amounts of material each time, and checking the progress.
Now with the muffler fitting perfectly through the cowl, I added the
fuel lines. My original intention was to feed the muffler pressure line
out through the same hole as the muffler itself. However, the pressure
tap turns out to be too close to the cowl, and there's no way to attach
the line without kinking it over. A fourth hole is necessary to get the
on the muffler pressure line.
It quickly became evident that I needed two more small holes on the
opposite side of the cowl to access the muffler bolts. These were easy
enough to locate using another piece of cutoff pushrod chucked up in
Later on when I went to install the battery hatch / canopy, it was
clear that the cowl needed some more tweaking, as the canopy would not
slide under the cowl as it should. It took a good amount of extra
effort to adjust the cowl so the canopy would slide in place while
maintaining alignment at the nose. My recommendation here is to make
sure the canopy is in place during the entire cowl fitting process to
avoid this frustration. In the end, I ended up with an absolutely
microscopic gap between the spinner and cowl that impressed even the
most experienced builders in my club.
cutoff pushrod leftovers make great locating pins.
the pushrods to the muffler mounting lugs through the engine
the pushrods to punch holes in the paper.
the muffler mounting hole locations to the cowl.
the muffler itself as a template for marking out where to cut.
result is a hole that's good enough for government work.
the cowl fit is finalized, it's time to install the switch, receiver,
Yet another of the many nice touches that are part of this Zlin' design
are the lite ply switch plate backers. There's a version for the Hobbico
heavy duty switch, a version for a standard switch and separate charge
jack, and a version for the Great Planes
switch/charge jack mount, which I happened to have. How you set the
charge jack up is your personal preference, but I normally set them up
so push is ON. That way it is impossible to accidentally turn the radio
OFF by bumping the switch. I'd rather have a dead battery from an
accidental switch bump, than bump the switch off on a running plane at
plywood backer pre-cut to fit the Great Planes switch mount.
the plywood backer to locate a suitable area on the fuselage and mark
makes for a nice clean installation.
installation is straightforward using the included velcro strapping and
slots laser-cut into the servo tray.
TIME TO FLY!
sneak peek at the completed airframe.
Maiden flight day was definitely not ideal for flying. At noon, the
winds were pushing up around 20 miles per hour, with gusts up to 26MPH.
But it was sunny, and this time of year, you never know when you're
going to get another chance to do a test flight. It's quite possible
there won't be another decent weekend day, so I went for it.
It's been a while since I've had a new glow engine on anything but a combat
plane, and from past experiences, I was expecting at least a short
breakin period. I was also expecting to do some carburetor tweaking due
to the inverted installation. This OS
.55AX is impressive. Priming the engine is a little tougher with the
inverted carburetor, but once it got a whiff of the Byron 15%, we were
off to the races. The engine ran so well there was no point in wasting
fuel on the ground. Time to fly.
With all the wind, the poor Zlin had all it could do to taxi crosswind,
let alone turn downwind, but there were no tendencies to nose over. If
it was ever going to nose over, that would've been the time.
Persistence paid off and after quite a bit of stick waggling, I managed
to get it in position for takeoff.
Long story short, it flies as good as it looks. The first flight was a
short one, a trim-and-tune. After a couple of low passes for the
camera, and the obligatory first roll, I brought it down for its maiden
landing. Hopefully you'll hear the wind pick up and REALLY start to
howl just as the Zlin swung onto final approach in the first video. It
wasn't my best landing, but even our "tamed 3D pilot" was bouncing some
As I suspected, the Zlin is fast, smooth, and aerobatic. Sport fliers
will like it because when you push the left stick forward, it shoots
ahead like a bullet. Aerobatic fliers will like it because of its
neutral handling tendencies, though they may find the recommended
throws a little slow, even on high rates. In the right hands, such as
those of our tamed 3D pilot, I bet it would even hover and harrier, but
it's not going to win any 3D competitions.
Right out of the box, the Zlin has the least control coupling of any
.40-size plane I've flown. It'll only take a tiny bit of aileron mixed
in with the rudder for a perfect rudder-only knife edge pass. Stock, it
wants to roll away from the rudder input just slightly; you'll see that
in the low knife-edge pass where I end up having to abort because the
Zlin was rolling inverted on me. To be knife-edge, that low, in that
much wind, on the second flight no less, is a testament to the
confidence that the Zlin instills.
since I started flying, I've wanted a Super Chipmunk. There were two
problems with that: First, it seemed like every third RCer I knew had
one. Second, the only version available was a kit, and kits take time
Great Planes's new Zlin Z-526 Akrobat solve both of these problems for
me. It's rare to see this plane modeled, let alone produced in a
sport-scale ARF form. There's no "been there, done that" when you show
up at the flying field with this airplane, but it still has that 1960's
aerobat appeal. Designed with fast, easy assembly in mind, it's perfect
for today's modeler on the go. It took me a week of evenings to get
from kit form box to runway; keep in mind that I was also taking
pictures for this review, so your 15 hours will be a lot shorter than
my 15 hours.
One of these days, I'm going to have to get a balsa-and-ply kit and
build it just to see if I can still do it! The only aspect of putting
the Zlin together that reminded me at all of my kit-building days was
the cowl install. Otherwise, it was simply too easy!
The comments, observations and conclusions made in this review are solely with respect to the particular item the editor reviewed and may not apply generally to similar products by the manufacturer. We cannot be responsible for any manufacturer defects in workmanship or other deficiencies in products like the one featured in the review.