58 MODEL AVIATION
Plane Talk: 3D Hobby Shop Osiris ARF
JOE AND CHRIS HASS
A design by
National Pattern Champ
Andrew Jesky
RC AEROBATICS (Pattern) aircraft are
some of the best-flying designs available.
So everyone should have one, right?
There have always been two issues
with acquiring a Pattern model: cost and
complexity. However, 3D Hobby Shop
(3DHS) has solved both of those problems
with the introduction of the 62-inch-span
Osiris.
National Pattern Champion Andrew
Jesky designed this airplane to mimic the
performance of a full 2-meter Pattern
aircraft. The Osiris has a very high level of
prefabrication that will get it into the air
quickly.
Our model arrived in a plain brown
box; there were marker arrows at one end
with instructions to “open here.” Opening
that end revealed a plastic bag containing
four 4-40 bolts with washers.
Those parts must have been missed
during the original packaging. Rather than
taking the chance that they would be lost,
3DHS made sure that our attention was
drawn to their location.
Opening the rest of the box revealed a
well-packaged aircraft, with all the pieces
in individual plastic bags. And surprises
abounded!
The landing gear halves were
completely assembled with axles, and the
wheels and wheel pants were attached. All
control surfaces had the CA hinges and
control horns installed, and the rudder
cables had been installed.
The cowl had a wet-look finish that
perfectly matched the UltraCote. Carefully
placed carbon fiber (CF) reinforced the
wooden structure. Even the elevator joiner
was reinforced with CF.
In keeping with current technology, the
14-page assembly manual was available
online. It was well illustrated with plenty
of great pictures.
The instructions began with how to
contact the staff at 3DHS, the requisite
safety notifications, and the items needed
for assembly. Pay special attention to the
warning not to use alcohol-based cleaners
on the painted surfaces. Our guess is that
the paint is not fuelproof.
Assembly: Four bolts quickly attach the
landing gear to the fuselage. This
stabilizes the model on the bench so that
you can install the rest of the parts.
Cut openings for the horizontal
stabilizer and elevator servo. The
horizontal stabilizer is slid into the
fuselage without removing the covering
from the center-section.
A call to 3DHS confirmed that the
horizontal stabilizer can be safely attached
to the fuselage with the covering still
attached. Many builders slice too far when
removing the covering and actually
weaken the stabilizer.
The only problem in the entire
assembly was that the fit of the stabilizer
to the fuselage was slightly loose at the
LE. A little shim stock or a fillet of epoxy
quickly solves that problem.
Instructions for aligning the stabilizer
are perfect; ditto for the tail wheel bracket
and rudder. The elevator joiner is adhered
to one of the elevators and, after curing, is
slid through the fuselage.
This was the only place where we
deviated from the instructions; we did not
secure the elevator hinges on the first
elevator half until the other elevator half
was secured to the elevator joiner. It was a
bit easier to center the elevators with both
sides free to move.
Ensure that the second elevator is
aligned with the first, by viewing from the
TE, before permanently attaching the
elevator joiner. Why the rudder is installed
later is clearly understood.
All pushrods, ball links, rudder cables,
The Osiris is respected by the RC Pattern
community as a worthwhile practice model
and an excellent primary aircraft for the
Sportsman-level competitor.
02sig2_00MSTRPG.QXD 12/20/10 12:12 PM Page 58
February 2011 59
The level of prefabrication is groundbreaking. Top-grade hardware is preinstalled.
Available in two schemes, the covering is high-quality heat-shrink film.
The Osiris is intended to be electric only
and is sized/powered to work with popular
five-cell battery packs that are normally
used in 2-meter airplanes.
Notice the correct crimp method that the
authors used on the provided multistrand
cable. Ball-link hardware is popular because
it offers zero lash and free movement.
The large hatch is secured with a series of
magnets, spring-loaded top latch, and
optional screws at the rear. Hybrid
wood/carbon laminations are used
throughout.
Heavy-duty pushrods on the ailerons and
elevator ensure direct servo input. Hitec
digital servos with Karbonite gears are
recommended and used in this review.
A good practice model should perform as
well as the contest version. The Osiris
wingtips are similar to those on modern 2-
meter Pattern aircraft; they promote
clean snaps.
Outer sheeting is relieved to form a shallow pocket that receives the wing panel. It’s a
clean look that offers the tightest joint and prevents wing flex.
Photos by the authors
and mounting hardware is included. The
elevator pushrod is stiffened with carbon
fiber. Instructions for installing the rudder
cable are excellent.
Hitec HS-5245 digital servos are used
at all stations. Included with the servos are
metal servo arms, which provide a firm
base for attaching the ball links. We use a
Du-Bro extra-large, heavy-duty servo arm
on the rudder servo.
Anticipating the variety of motor
choices facing the customer, 3DHS
includes a plethora of motor-mounting
hardware. Because it’s our favorite, we
used the recommended Hacker A50-12S
with supplied long motor spacers.
Once the motor is mounted, the cowl
can be attached. There are great
instructions for that too.
We completed the power system with a
Castle Creations Ice 85-HV ESC; a
Hyperion five-cell, 5000 mAh Li-Poly
battery; and an APC 16 x 10E propeller. A
Great Planes 2-inch white aluminum
backplate spinner finished the nose.
The ailerons are hinged to the wing
panels, so the only thing necessary to
complete each side is to install the aileron
02sig2_00MSTRPG.QXD 12/20/10 12:15 PM Page 59
60 MODEL AVIATION
Look carefully at the control surface position; no input is needed to hold inverted.
This airplane’s natural level attitude even in knife-edge flight is a prized design quality.
Pluses and Minuses
+•
Superb prefabrication and construction.
• Fantastic flight performance.
• Provided hardware is strong and slop
free.
• Availability of two color schemes.
•Well packaged and serviced by the
manufacturer.
-•
Paint used is not solvent safe.
Specifications
Test-Model Details
Andrew Jesky has been performing RC Aerobatics,
or Pattern, at the top level and has made a measurable
impression on the AMA and the international precision
RC pilot community with outdoor as well as indoor
models. You’ll even see him fly a helicopter now and
again.
His ability to cross-pollinate skills from a number of
RC disciplines has had an influence on his peers and the
judges. Teaming up with 3D Hobby Shop (3DHS) owner
Ben Fisher seemed like a natural blend of resources and
talent; Ben and Andrew have both.
In all sizes offered, the 3DHS AJ Slick shocked IMAC
(International Miniature Aerobatic Club) pilots with easy
handling, high performance, and the ability to fly on rails
directly out of the box. That allowed the RC flier to
focus less on trimming the model and more on honing
his or her proficiency and maneuver geometry.
The Osiris has made a profound impression on
members of the Pattern community, who can be
profoundly picky. They need aircraft that are built to be
as light as possible, as strong as possible, and as accurate
as possible—all in designs that are capable of performing
a complex list of maneuvers.
3DHS looked at what the Pattern community had
been presented, which were products that, frankly, left
much to be desired. The wish list was fat with ideas and
full of room in which to make an impression.
Ben and Andrew set out to test some theories with
the 62-inch-span Osiris. It does fall short of the 2-meterspan
airplanes that are normally flown in Pattern events,
but it proved that they can offer an airframe that is light
and has a power-to-weight ratio that leaves nothing to
be desired.
Model type: RC sport ARF
Skill level: Intermediate builder;
intermediate pilot
Wingspan: 62 inches
Wing area: 725 square inches
Length: 65 inches
Weight: 6.0-7.5 pounds
Wing loading: 19-24 ounces/square
foot
Power: 1,000- to 1,300-watt system
Radio: Four channels minimum
Construction: Balsa, light plywood,
carbon-fiber reinforcement
Finish: UltraCote, high-gloss paint on
plastic and fiberglass parts
Price: $379.99
Motor: Hacker A50-12S
ESC: Castle Creations Ice 85-HV
Battery: Hyperion five-cell, 5000 mAh
Li-Poly
Propeller: APC 16 x 10 electric
Motor amperage: 69 maximum
Motor voltage: 18.6 under load; 21.0
with no load
Motor output: 7,700 rpm; 1,290 watts in
Radio system: JR X9303 transmitter,
Spektrum AR7000 receiver, four Hitec
HS-5245 servos
Ready-to-fly weight: 6 pounds, 14.5
ounces
Flight time: 6 to 10 minutes, depending
on type of flying
The pair settled on electric power because it features
assets that can help obtain a light airframe. The beauty of the
Osiris is that it’s large enough to match any .90-glow-powered
offering, yet light enough to use only half of a 10S pack, which
F3A (FAI RC Aerobatics) pilots who fly with electric power
typically use. If you’re new to this type of model, the packs
you’ll buy will gear you up for graduation.
The Osiris flies almost perfectly neutral in all attitudes. To
understand why, compare the shape of the fuselage and area
to that of the wing; they are close. The Osiris presents (to the
judges) so that the fuselage is perfectly in-line with the flight
path. It doesn’t yaw or pitch away, to distract from the
intended shape of the maneuver.
The size and shape of the control surfaces also help the
Osiris pilot perform maneuvers well. They are not “oversized”;
they are appropriately sized to allow the flier to perform all
possible sequences up to the world-championship level.
The FAI catalog is filled with complex maneuvers (which
are similar to 3-D stunts, only bigger)—all of which hype up
the sport pilot to fly when executed at low altitude. Rolling,
knife-edge, and crisp snaps sell a Pattern model to the
educated pilot.
All of the preceding equals what any RC flier, whether
competition or novice, would want. With a small amount of
effort, or a high level of debt, the Osiris can help its pilot focus
on flying—not how to keep an engine running (electrics always
start), how to add a program mix, or what surface to untwist.
The Osiris is a winner, and it might help you become one too.
Best of luck to Andrew Jesky and the US team at the FAI
F3A World Championships in Muncie, Indiana, in July. We
hope that he and Ben have plans for those RC pilots who will
want a larger Osiris in the future. MA
—Michael Ramsey How It’s Done
02sig2_00MSTRPG.QXD 12/20/10 12:19 PM Page 60
February 2011 61
servos and linkages. The ball-link
hardware is exactly the type we would
have selected.
The wings are attached to the fuselage
with a combination of a CF wing tube, CF
antirotation pins, a plywood locking tab,
and a nylon bolt. The wing is neatly
recessed into the fuselage, for a crisp fit.
The canopy is held in place with a snap
latch mounted on the turtledeck and a
nylon bolt on each side of the fuselage.
This makes accessing the battery
extremely easy.
Flying: The recommended control throws
and CG were at excellent starting points.
The first flight revealed precisely how well
the Osiris was designed and constructed;
no trim was required.
Vertical performance is excellent.
Maneuvers are crisp and tight when needed
and large and powerful when desired.
Snaps have that locked-in look. No rudderto-
elevator mixing is required for perfect
knife-edge flight. Slow flight is steady.
Takeoffs and landings are solid and
predictable. This model tracks like it is on
rails.
This airplane performs as great as it
looks. If you plan on flying aggressively,
invest in high-quality batteries with a high
discharge rate.
You can get your model into the air in a
minimal amount of time. And thanks to its
engineering, fewer flights are required to
trim and mess around with radio
programming.
3DHS has made it easy to get into
Pattern. Give it a try. You will be glad to
have this Osiris in your fleet. MA
Joe Hass
joehass@gmail.com
Chris Hass
chrisjhass@gmail.com
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Manufacturer/Distributor:
3D Hobby Shop
603 FM 2093 Suite 1303
Fredericksburg TX 78624
(830) 990-6978
www.3dhobbyshop.com
Sources:
Hacker
www.hacker-motor.com
Castle Creations
(913) 390-6939
www.castlecreations.com
APC
(530) 661-0399
www.apcprop.com
JR
(800) 338-4639
http://jrradios.com
Spektrum
(800) 338-4639
www.spektrumrc.com
Hyperion
www.hyperion-world.com
Du-Bro
(800) 848-9411
www.dubro.com
Hitec RCD
(858) 748-6948
www.hitecrcd.com
Great Planes
(800) 637-7660
www.greatplanes.com
02sig2_00MSTRPG.QXD 12/20/10 12:22 PM Page 61
