Plane Talk: Great Planes Super Skybolt ARF - 2008/02

WHEN THE SKYBOLT arrived, it was
appealing right out of the box and
immediately captured my interest. Before
beginning assembly I made a thorough
inventory of all the parts and gathered all
materials I planned to use to complete the
project, including the radio gear.
A good first step I take when starting any
project is to gain a general familiarity with
the build by reading through the instructions
completely to eliminate any unknowns that
sometimes come up during the assembly
process.
Construction: I completed the hinging
process on all four wing panels using the
provided cyanoacrylate hinges and my Tpins.
I inserted the hinge halfway into the
ailerons and inserted a T-pin to prevent the
hinge from going in any farther when it
came time to slide the ailerons onto the wing
panels. The T-pins are removed before
gluing the assembly together.+•
Highly detailed and decorative
MonoKote covering
• Easy-to-understand assembly
instructions and illustrations
• Simple thumbscrews captured in wing
struts ease installation
• Aluminum spinner included
-•
Cowl screws should be installed with
silicone to keep them secureMounting the wing servos was a breeze.
Using the provided pull strings within the two
lower wing panels I installed the servo
extension cables and secured the servo cable
plugs with a connection lock.
I mounted the aileron control horns, then
using the provided pushrod and clevises I was
able to complete the installation by threading
the clevis to the pushrod, and I connected it to
the servo control arm. I made a mark on the
pushrod where it connects to the aileron
control horn and made a bend, and then I
secured it to the aileron with the provided
nylon keeper.
Joining the two lower wing panels was a
simple two-step process. I glued the two
plywood wing joiners together, and then I
inserted the structure into the lower wing
panel with a generous amount of 30-minute
epoxy. With the two nylon wing bolts
through the holes, a couple of rubber bands
were wrapped around them to hold the wing
panels together tightly until the epoxy cured
completely.
The top wing halves use an antirotation
pin, basically a small wood dowel, and the
tapered wing joiner; the taper faces forward.
Using 30-minute epoxy on the wing joiner
and the face of the rib, I assembled the wing
panels with the metal center rib so that the
tabs point down.
The fuselage assembly started with the
installation of the fin and horizontal
stabilizer. After the marks were made
along each joint where they met the
fuselage, I removed a portion of the
covering to expose the wood surface where
the parts would bond to the fuselage.
Always use 30-minute epoxy at these joints.
To accurately install the horizontal
stabilizer I mounted the lower wing to the
fuselage and measured from the same
point on both wings’ TEs to the outer tip
of the horizontal stabilizer. This ensured
that I had the same distance on both
sides.
The elevator halves are hinged in the
same fashion as the ailerons. They are
connected with a U-shaped joiner and30-minute epoxy.
Installing the rudder and elevator servos
went quickly and easily; I only had to drill
the pilot holes for the mounting screws. The
pushrods just slid into the preinstalled
guides once I removed the covering where
they protruded through the fuselage side.
After lining up the pushrod with the
elevator and rudder, the control horns were
secured with the provided hardware.
I made a mark on the pushrod at the
servo control arm and made a 90° bend. The
rudder and elevator pushrods were secured
with the provided nylon keepers. The two
pushrods for the elevators are joined with
two wheel collars, and the longer of the two
pushrod wires connects to the servo.
The tail-wheel assembly consisted of the
tail gear, nylon retainer, tail-gear bracket,
and tail-wheel mount. The tail-wheel mount
was a grommet type inserted into the hole
in the rear portion of the fuselage, and the
retainer was inserted into a pilot hole drilled
into the bottom of the rudder. I secured the
retainer and tail-wheel mount in place with
a bit of epoxy.
The main landing-gear installation went
off without a hitch. The main axles were
mounted in place with nylon locking nuts,
and the wheel pants just slid in place and
were secured with two 4-40 Phillips-head
machine screws. I attached the main
landing gear to the fuselage with six #4
screws.
Installing the cabane struts wasn’t at all
complicated. Each assembly slid into the
slots within the fuselage. To get the holes
aligned properly I used a piece of 2-56 wire
to hold the cabane in place while the 4-40
mounting screws were inserted.
The three-line fuel system came with all
the required hardware contained within the
fuel tank. After the fuel tank was assembled
I attached three lines that were
approximately 12 inches in length, leaving
the fill line available to come through the
side of the fuselage for the fuel dot. I
secured the fuel tank with a rubber band
stretched across the back of it to the retainer
tabs.
The kit came with a two-piece
adjustable engine mount that was secured
with 8-32 sockethead screws into T-nuts
contained within the firewall. Before I
tightened the engine mount I used spring
clamps to hold the engine on the mount so
the thrust washer would be set 57/8 inches
from the firewall. The engine was installed
with the provided socket-head screws and
nylon locking nuts.
The muffler fit perfectly within the
recess of the fuselage. Before locking it into
position I applied high-temperature silicone
to both ends of the exhaust manifold
threads. I marked where the pushrod should
come through the firewall and drilled a pilot
hole to accommodate the pushrod.
Installing the throttle servo was
accomplished in the same manner as all the
others: with a predrilled pilot hole for each
mounting screw to prevent the wood from
splitting. Using a screw-lock connector gave
me the final necessary adjustment; the other
end is connected to the engine control arm via
a nylon clevis.
I chose the Maxx Products soft-mount,
one-piece charge switch with LED voltage
display, and I mounted it centered in the gold
strip just above the bottom wing LE. The
three LEDs (green, yellow, and red) show the
battery status at a glance, and the switch was
mounted with a silicone gasket for long life.
The unit is compatible with 4.8- and 6.0-volt
flight systems. I like it because when I move
the control surfaces the lights will alert me if
there is problem.
Approximately 3 inches forward of the
switch I mounted a fuel dot for the tank. To
get as close to the recommended balance point
as possible I mounted the receiver battery just
above the landing-gear assembly with Velcroand impact foam to keep it from shifting
position. I had to add only a couple ounces
of lead weight to the bottom of the engine
cowl to get the balance right on the CG.
The printed template for the engine cowl
in the back of the instruction booklet
provided a close approximation for the
engine cutout. Once I cut the opening in the
cowl I installed it using masking tape to
properly center it and made the final
enlargements for a perfect fit. I installed the
tinted cockpit canopy with the screws
provided.
The thumbscrews on the wing struts were
a quick, efficient way to attach the wings.
Using a little epoxy on the locating wooden
pegs is a good idea. The Skybolt also came
with a strip of hardwood to act as a lower
wing shoulder for the nylon bolts. For a
good joint I clamped this part in place while
the epoxy cured and then drilled out the
clearance holes.
Before attaching the wings to the
fuselage I marked the center of the TE of all
four ailerons and installed the control horns
used to couple the upper and lower ailerons.
Each of those small control horns was
trimmed down to the last hole for connection
purposes.
The metal center rib in the top wing
attached to the fuselage cabane with two 4-
40 socket-head screws and lock nuts. The
linkage between the top and bottom ailerons
was made from the supplied 2-56 control rod
and the nylon hardware. The control throws
were set up with the recommended high and
low rates, with 35% exponential
programmed into only the high rate.
After several rotations of the propeller to
prime the engine, the O.S. .91 fired up
effortlessly and ran like a top. It’s a good
idea to check the high and low needle-valve
settings on the engine to make sure it will
idle well and not go lean on takeoff.
At less than half throttle, and a bit of
back pressure, the Skybolt tracked perfectly
down the runway and gently eased off the
ground. The wings remained rock steady and
level as the model climbed out to aerobatic
altitude. I applied only a small amount of
trim adjustment to achieve hands-off
straight-and-level flight.
One way to determine how close I have
the balance point is to trim the airplane for
straight-and-level flight and then roll it
inverted. If it pitches down, it’s slightly
nose-heavy; if it tends to pitch up, it’s
probably a little tail-heavy.
Some biplanes, although balanced
perfectly, are pitchy, leading you to believe
that they might be tail-heavy when they’re
not. This problem may be a result of wing
incidence.
The Skybolt is error-proof right out of the
box. Its mounting system gives you a
negative 2° on the top wing and a negative
1° on the lower wing, with the horizontal
stabilizer set at 0°. This in combination with
the engine offset at 2° right thrust and 1°
downthrust gives the Skybolt unprecedented
performance.
The Skybolt’s top wing is swept back,
which helps lower wind resistance while
providing better penetration through the air.
The lower wing is straight with approximately
12° of dihedral, giving the Skybolt more
corrective in-flight stability.
I used the Futaba 9Z mixing to couple
the aileron and rudder 25%, which made the
Skybolt perform like a simple sport airplane
in the turns. It was a dream to fly.
It amazed me how well and stable this
aircraft flew. I put the Skybolt through its
paces with basic aerobatic maneuvers such
as large Loops, which required only a small
amount of rudder to compensate for drift.
The model performed spins and stalls in a
predicable manner.
Rolling maneuvers were straight-andlevel,
and the Skybolt performed
combination stunts such as inverted flight,
Cuban Eights, Stall Turns, Split “S”s, knifeedge
flight, and Outside Loops with
amazing ease, with more than ample power.
Some 3-D maneuvers, such as Blenders,
Torque Rolls, and Flat Spins, are possible as
well.
The APC 14 x 4W is, without a doubt,
the perfect propeller for this setup, and it
proved itself on takeoff and landing. Even if
the approach was slightly high and fast, the
propeller provided enough resistance to
slow the model for a perfect landing.
The Great Planes Super Skybolt ARF is a
sweetheart of a biplane and a joy to fly. It
doesn’t seem to have any bad habits and
possesses stable slow-flight characteristics. I
was initially afraid that it would tend to tipstall
at low airspeeds, but to my surprise it
was gentle and predictable.
This model is a gem and would make a
great addition to anyone’s hangar. MA
Al Morris
[email protected]
Manufacturer/Distributor:
Great Planes
Box 9021
Champaign IL 61826
(217) 398-8970
www.greatplanes.com
Products Used in Review:
LED Switch (item 5470):
Maxx Products International
(847) 438-2233
www.maxxprod.com
Servo extensions, Y harness, 2150 mAh
NiMH battery:
Radical RC
(937) 256-7727
www.radicalrc.com
Other Review Sources:
3D Flyer, November 2006
Fly RC, December 2006
Model Airplane News, December 2006
R/C Report, June 2007