BY: Mike Lee
One of the most eye-opening biplanes to take to the skies in modern times
has to be the Ultimate Biplane. Originally intending to upgrade the looks and
the performance of the Pitts Special, the designers ended up with an entirely
new airplane that was used extensively for flying aerobatics. Naturally, this
aircraft is very popular with the modeling public, and this review deals with
a nice, small airfield version by The World Models, the Ultimate EP.
ith a 36-in. wingspan,
the Ultimate EP may
seem compact by
the numbers, but this illusion
disappears once you start putting
the airplane together. The
structure is all wood, using balsa
and plywood that is laser cut and
jig assembled. As an almost-ready-
to-fly (ARF) airplane, this model is
going to get from box to runway
quickly, so let's dig in.
System Check
Before putting the Ultimate EP
down on the runway, we performed
full systems and range checks with
both motor off and motor running.
You can never be too safe! Our
system check included making
sure we had the control movement
set correctly. Our initial set-up was
in accordance with the instruction
Control Throws
Up Down
Elevator: 15mm 15 mm
Rileron: 05 mm 05 mm
Rudder: +/- 30 mm
I used only high rate controls
during my set-up, as there was no
recommendation for high and low
rates. None of these settings are
sufficient for performing radical
3-D type flying, as the model was The tailwheel on the Ultimate is nicely done as shown here. Notice how it mates to
ype Lying the rudder and hinges through a plastic hinge.
not intended for that use.
In Flight
Our first flights were performed
on a calm morning with a
temperature of about 68 degrees. p= = de a
All controls were given a final | | р
check. We set the Ultimate EPon | pt
the dirt airfield strip for its launch,
and the airplane was given 3/4
throttle for the takeoff. The Ultimate
EP consumed only 40 ft of ground
to get airborne. John reported two
clicks of down elevator trim to get
it flying hands-off.
The handling of the Ultimate
EP was surprisingly good. It felt
like a larger aircraft, with a solid
feel and nothing funny going on.
Rolls were very axial for a biplane,
requiring very little elevator
as the airplane rolled through @ A look at the front motor mount shows the interlocking plywood parts that make
for a strong mount. Note the laser cutting.
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RC-SF.COM | 125
i A
Using the kit's wing alignment jig, it is easy to get the wings mounted
correctly. Here, they are in place as we mount the top wing.
inverted. Loops were about 75 ft in
diameter to look good, but not too
tight. The amount of power from
the motor was well matched to the
model and the intended user. It is
not over-powering with unlimited
vertical power on tap, but, for the
sport pilot, it has enough to pull all
the non-3D stunts you could want.
And it does most of them nicely.
Knife-edge flight can be done
with some slight adverse pitch
to the belly, and a hint of roll
coupling, but the Ultimate EP will
hold an honest knife edge. It will
also perform a nice flat rudder
circle, as well as snap rolls on
demand — as many as you want.
Given that the Ultimate can
barnstorm, we tried the slower
end of the flight envelope. At slow
airspeed, the airplane behaved
well and was not tipsy or snappy.
When it stalled, it seemed to fall
away to the right consistently, and
required some power and a bit of
elevator to come out. Spins, both
positive and negative, were tight
and easily controlled. The Ultimate
EP took everything I could throw
at it without complaint.
Landing the Ultimate EP was a
non-issue. It is a bit slicker than the
average biplane, so the approach
is more like that of a monoplane.
The assembly process begins with reading the
10-page instruction manual, which has plenty of
photos to guide you along. You will notice there are
two foam wing-Jig guides to use when mounting the
wings — a nice touch. Also note that each step of
the assembly is numbered, with the parts needed for
each step contained within a numbered parts bag for
you. | think all manufacturers should do this.
We start with the two wings by setting the
hinges into the pre-cut hinge slots. The model uses
cyanoacrylate (CA) -type hinges. To keep them
from moving out of place, there is a small piece
of string in the hinge. Remove the string, hit the
hinge with thin CA adhesive, and you're done with
hinging. Aileron servos are placed in the lower
wing, and you will need a Y connector to join the
servos to the receiver. Work this carefully, as the
servo wires from our JR Sport SM22 servos were
not long enough to reach the holes in the wing at
center for the wires to exit.
We now move right back to the tail feathers,
and the instructions show that the two elevator
halves are joined by a plastic joiner/control horn.
The horizontal stabilizer is mounted into the
fuselage first, followed by the joiner piece and
then the elevators are hinged and mounted. An
easier method is to slit the covering from the
stabilizer slot all the way to the tip of the tail, and
the small piece of balsa that resides at the tail will
slide out. This allows you to slide the horizontal
It was not necessary to carry any
power on final, as the airplane
flared well and held it for quite
awhile. This allowed it to kiss the
runway so very nicely for a long Opinion
roll-out and taxi to the hangar. Hey, The World Models has really
this biplane is fun! raised the bar on the quality
of this product. The nice
This pilot is ready for action!
stabilizer with the elevators already attached from
the rear without a problem. The instructions don't
tell you about the small replacement piece of balsa,
already covered with film, that you should use to
backfill the slot, but it is there for you. Nice!
The vertical stabilizer and rudder is next to
assemble, and these are a breeze to place using thin
(A adhesive, Atthe bottom of the rudder, weinstalled
the steerable tail-wheel assembly. Finishing off the
tail feathers are the control horns. We find that the
Ultimate EP has small puncture marks in the film
covering that indicate where to drill the holes for
the control horns for proper alignment. This is very
thoughtful design.
We can now move on to the nose, where we
mount the KM0283010 kit supplied motor. The
firewall is pre-drilled to accept the mounting screws,
which are perfectly aligned to get the motor wires to
hang straight down from the motor, curving on into
the nose for connection to the ESC inside the nose.
Mount the cowl, which is made from fiberglass and
has a dead-on color match to the iron-on covering.
The cowl is attached with four wood screws, and
then you can install the propeller and spinner
Nextis the main landing gear. This is a polished-
aluminum strut that is attached with three machine
screws. To locate the screw holes, just press your
thumb on the covering in the area of the holes, and
you will feel the placement. Poke a small hole in the
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covering and mount the strut in place. The model is
full of nice details like this.
On the tips of the landing gear strut are the kit
wheels with wheel pants. These look a bit different
when compared to the real thing, but they do add a
lotto the overall looks. If you fly from grass, you may
Wish to leave them off to prevent the model from
tripping on the grass.
We now move to installing the radio gear. Our
choice of radio gear for the Ultimate EP was JR Sport
SM22 servos for all control surfaces. They weigh
only 9 grams each and put out 20 oz-in. of torque.
They also happen to be a perfect fit to the servo
mounts inside the Ultimate EP. You will need one
servo for the rudder, one for the elevator, and two
for the ailerons. The rudder and elevator pushrods
are inserted into the pre-installed pushrod tubes for
a quick fit up. Aileron pushrods are out in the open
on the top surface of the bottom wing. Listening to
the JR X9303 transmitter is a JR R700 receiver. The
ESC resides in the nose compartment, and we used
a Castle Creations Thunderbird 18 unit. It is virtually
lost inside the nose section, but a bit of hook-and-
loop material keeps it in place.
You'll mount the main wings at this point. Start
by mounting the lower wing to the fuselage wing
saddle and bolting it up tight. Now find those foam
wing alignment jigs we mentioned before and slide
them on the lower wing. You can now slide the upper
wing into the wing jig and begin installing the cabane
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struts at the wing center followed by the outer wing
struts. The jig makes it a quick and easy chore.
Our Ultimate EP is finished off by inserting
the pre-painted pilot figure into the cockpit and
then adding the canopy glass. This biplane is now
We did find one item that needed correction,
and this was a minor warp in the upper-left wing
panel. À 5-minute date with the heat gun cured this
problem in a hurry, and we were ready to go.
The Ultimate EP is balanced at 3.25-in. back from
the leading edge of the top wing. To do that with an
Apex 2100-mAh 3S1P LiPo battery pack, we simply
had to slide it into the lower nose compartment for
perfect balance. The battery pack weighed in at 5.6
oz. My model's all-up weight with battery pack was
28.3 oz. The recommended weight was 27 07, so we
were satisfied with the end results.
* Pushrod sleeves are in place already.
* Great fit of the motor to the firewall.
* The cowl to spinner fit is good.
* Weight with Apex 2100-mAh 3S1P battery
is 28.3 oz. Recommended weight is 27 oz. No
balance weight was needed.
* Warp was found in upper left wing panel.
* Lots of space in the cabin for radio gear.
* Motor rpm = 7400
RC-SF.COM | 127
The World Models Ultimate EP ARF
Model Name
Pilot Skill
Aspect Ratio
ai selage Length in.
Total Wing Area
Tr Airfoil
| Stab Airfoil
Fin Airfoil
NENA Ready
to Fly
Wing EA
a eE
Ultimate EP ARF
Intermediate Ге) [о
36 in,
бп. both o
4325 Sq in.
Flat plate
E-flite 60-amp Pro =
Flat plate
28.3 07 as rel
94302/5q ft ©
Ailerons, E Rúdder
Balsa. hd Lite- vs
| Motor
Speed Co ntroller
Apex 3-cell 2100-mAh LiPo
Castle Creations
Thunderbird 18
10x6 Folding Electric
Manual Quality
Dean' Ultra plug
13.1 amps @ full throttle
145 watts
9 to 11 minutes using partial
JR R/00 Rx
JR SM22 @ servos) _
Balsa and Lite-Ply
Minor assembly only
Radio, battery, ESC,
extensions, etc.
® touches that The World Models
added to this small-scale product
proves they mean business. The
Ultimate EP is a fine example of
good engineering and is a fine
performing aircraft, especially in
this size class. It is very complete,
with full hardware and even the
motor and propeller to power it.
This airplane has become one of
my favorite models to take to the
airfield, because I can wring it out.
The Ultimate EP takes all I can fly,
and I like this in an airplane. SZ
The World Models Ultimate EP ARF
The World Models Manufacturing Co., Ltd
Unit 23-24, 10/F
Kowloon Bay Industrial Centre
15 Wang Hoi Road
Kowloon Bay, Kowloon, Hong Kong
Phone:852-2707 9783
Web site:
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