World Models 42%
Ultimate Biplane is made from high quality balsa and plywood
construction. It is available in two different color schemes
and is light weight yet strong for aerobatic maneuvers. The
model offers hand-painted fiberglass cowling and wheel pants.
It comes with strong 1/4" thick aluminum landing gear and
all the hardware needed to complete the arf.
I had done many electric conversions on other World Models planes
so the time was right to start building a giant scale Ultimate
Wing Span: 98 in / 2489 mm
Wing Area: 3300 sq in / 213 sq dm
Fuselage Length: 104 in / 2640 mm
Flying Weight: 38lbs / 1720g
Engine Required: 150 cc gasoline engine
Radio Required: 6-channel radio w/ 17 servos
World Models 42% Ultimate is the same airplane as Chip Hyde''s
TOC airplane that was designed and built for him and then
produced by Aeroworks for several years starting in 2003.
After Aeroworks started their QB line of ARFs, made by a different
manufacturer, World Models continued to produce the old Aeroworks
Ultimate line (150, 100, 50cc sizes) under the Airborne Models
Noll flew the new Aeroworks 150cc 20-300 ARF-QB
Ultimate on electric power last summer at Joe Nall so
big biplanes have been a crowd favorite for many years!.
In the Boxes
42% Ultimate comes in three big boxes, two via Fed Ex, and
the biggest box (containing the fuselage) via Greyhound Express
wing box contains four wing halves. One wing set, shown right,
is slightly shorter than the other because it attaches to
the fuselage. The ailerons are taped in place and the covering
scheme is different on the top and bottom sides.
large decal sheets and a 14-page manual are also included
in the wing box.
box 2 of 3, we have the cowl and hardware. Again, everything
was well protected and arrived in perfect condition.
flawless cowl was beautifully painted and trimmed. The clear
plastic canopy was also ready to install. The painted pilot
was very well done and a nice added touch to the kit! Although
air-filled tires are also included, I have had problems in
the past with these tires from World Models so we'll see if
I decide to use them or obtain others.
spinner looked to be very good quality with an aluminum backplate.
The wheel pants were reinforced on both sides with fiberglass-covered
plywood so they can be used on either side.
in my 1/4-scale and 1/3-scale Cub reviews for World Models,
the tailwheel assembly looked top notch and the hardware bags
were all numbered to match the steps in the manual. It's little
extras like these that make The World Models ARFs a great
3 of 3 travels via Greyhound Express (aka Trailways) so you
need to pick it up yourself from the local terminal. My Ford
Expedition came in very useful for this big box!
this box, we have the fuselage, gear mains, and tail sections.
The yard stick gives you some perspective on the size of each
part. The aluminum gear mains is 1/4" thick and very
you need to use a step ladder for photos and your 5-month
old granddaughter can fit in the cockpit, you start to wonder
if you have gone too far!
Granddaughter not included.
ULTIMATE safety, I planned to use the following components.
Spektrum system provides true redundancy in receiver and power
to the servos. There are three receivers and two separate
receiver power supplies that are ORed together. If any one
receiver or power supply fails, the others take over. You
can also add an optional fourth remote receiver (sold separately).
A fail-safe switch operation is also provided. If the On-Off
switch fails, the receiver and servo power stay on. In the
Off position, the AR9100 draws less than 1mA.
I was at the 2010 NEAT Fair, I was presented with some evidence
by Rick Vaughn that using A123/LiFe cells without a regulator
provided a superior power system without glitches. He used
this device from XPS called a TattleTale.
It showed that his receiver power supply glitched when under
certain conditions like multiple servos reversing direction
at the same time. After he switched to using 2-cell A123/LiFe
packs directly, the TattleTale reported no glitches.
with this new information from Rick, I decided my Spektrum
AR9100 Power Safe receivers will be fed by two Hobbico LiFe
6.6v 3200mAh packs. The LiFe packs can be charged up to
1,000 times with no loss in performance. Further, no regulators
are required, reducing cost and parts count. Both packs can
be recharged at the same time using a single FMA CellPro 10s
charger. The combination of using the AR9100 Power Safe receivers
with dual LiFe packs provides an extreme level of safe redundancy.
made a short adapter to temporarily allow me to use the system
until I figured out where things will reside in the Ultimate.
A New Power System
decided to try the new Turnigy C120-70 outrunner. This motor
appeared to be similar to other designs on the market but
only 1/3 the price! The C120-70 is not made to order but rather
stocked so that it can be purchased quickly. This type of
affordability and off-the-shelf solution was right in line
with my goals for converting the Ultimate to a high-power
information on the motor was sparse, data had already been
posted using the ICE HV 160 ESC on a 12s LiPo and a 27x10
prop. At 7000 watts, 169 amps, 7200 RPMs, this setup will
run all day. My plan was to prop it for a peak of around 225
amps which the ICE HV 160 ESC should easily handle for 5 second
bursts. I planned to start with a 30" prop and see what
the CC ESC data logging reported.
main issue here was that the motor performance was really
an unknown. Would the quality be good enough for my giant
scale Ultimate? Should I mount it in the plane without testing
Turnigy CA120-70 motor arrived on a Sunday from China. The
EMS shipping is very quick!
took it out of the double boxes where it was surrounded by
cooler foam and sealed in a plastic bag. So far, it seems
as advertised and the quality looks good. The magnets are
somehow sealed into channels in the outer case. I'm not sure
how this was machined but it should help them stay in place.
the time I purchased my motor, the only available information
was the specifications seen below and the one Castle Creations
Data Logging report using a 27" prop. Many questions
remained about the quality and performance of this new Turnigy
motor. Noone had used it yet in a real application so I decided
that it must be checked out to my satisfaction before going
into my Ultimate.
as a 100cc gas engine replacement, this motor is a great
alternative for 3D and sport planes up to 35lbs! The
motor is very well built with strong mounts, end bell
and a concentric double bearings at the rear to support
large propellers and rotating can, especially during
hard 3D flight. This motor is very well engineered and
of the highest quality. The factory can produce only
a limited number of these motors per month due to the
increased time in balancing and machining such a large
the motor received 70V and 250A that would be 17.5 kW input.
Typically, motors and ESCs are not rated for both max voltage
and max current at the same time. This is all part of the
specsmanship. The total power level (voltage times current)
is what really limits these components. Further, there are
constant ratings and peak ratings so in applications like
R/C, you can often obtain a sizable increase of power for
short periods (5-10 seconds) which can be used for certain
maneuvers (knife edge, hovering, pull out, verticals, etc).
for the manufacturer's "110cc equivalent" suggestion,
their "20 h.p." is closer to a DA-200 power level
so you have to take these suggestions with a grain of salt
and perform some of your own tests.
ordered 8mm bullet connectors from both XPS
King. To my surprise, the ones from HK were much larger.
Further, you get a whole bag of 12 sets for $15. I plan to
use these on all ESC connections. For battery pack connections,
I plan to use the Castle Creations 6.5mm
connectors which can handle 200amps. These 6.5mm connections
will be paralleled (12s3p) going to the 8mm bullets.
made some measurements on the Turnigy CA120-70 motor and they
did not match up to the DA-150.
measured the prop adapter to be 29 mm across from the holes
which would make the mounting the same as the DA-100 and 3W
4-cylinder (112iB4) engines.
Building the Motor Test Box
about $10 at Home Depot, I picked up some #6 x 1" screws
and a 1/2"x6"x4' piece of Poplar. After a few hand
cuts, I was ready to make my test box. Poplar isn't a hard
wood but it is fun to work with and becomes plenty strong
if you put enough screws in it.
idea here is to clamp and tie the box to my portable Work
Bench and then move the portable station outside for testing.
My prop had not arrived yet so my next step will be to finish
the setup on the Work Bench and do a quick test on 6s at low
RPMs without a prop. The CC ICE HV 160 ESC will mount on the
side of the test box. I still needed to solder the 8mm bullet
connectors onto the ESC.
picked up a Heavy Duty Battery Cutoff Switch (66789)
for $10 at Harbor Freight Tools to use as my safety arming
switch outside the plane. The low-cost switch locks in both
the On and Off positions and is rated for 500 amps at 24v
which should be good for around 250 amps at 48v. The switch
weighs 7.7oz but I consider it a requirement for safety and
convenience on a giant-scale electric conversion that approaches
10KW of power. I'll detail use of this switch along with a
momentary push button anti-spark setup later in the column.
motor passed its first test. Not only does it run but it appears
to be vibration-free. I tested it on my work table using a
6s LiPo pack and was very happy that it appeared to run flawlessly
at a range of throttle settings. The Spektrum AR9100
DSM2 9-Channel PowerSafe Receiver and Hobbico LiFe
6.6v 3200mAh pack are inside the box.
started assembling my portable Work Bench to be used in the
outdoor prop testing. You can see my technique of clamping
and strapping the motor test box. The 12s3p LiPo packs will
sit on the left side.
mounted the HD Battery Disconnect Switch and the momentary
push button to my test box. In this setup, the operator presses
the button first, then pulls and twists the battery switch
for a spark-free arming of the power system. The momentary
push button connects a 100 ohm 1w resistor across the battery
switch to charge up the capacitors on the ESC within a second.
Castle Creations ICE ESCs
Castle Creations ICE ESCs are rated for a continuous current
draw with a 5mph air flow. The short term peak ratings are
not published. For normal flight, how often do you fly at
full throttle? Typically, we hit full throttle for 5-10 second
bursts when going vertical or doing a knife edge or a fast
fly-by (especially in jets). With a little experience, and
a few tips from others using the same controller, you can
make use of this extra capability.
look at some of the CastleLink screens I took snapshots of
when downloading my data logging. These are the actual settings
of my ICE HV 160 ESC for the CA120-70 motor. I went along
the tabs and took a snapshot of each one.
Data Logging is my favorite feature of the CC ICE ESCs. I
no longer need to stick my face and fingers close to the power
system running at full throttle to get a measurement. The
data is saved even after the ESC has been turned off! Once
downloaded from the ESC, with the motor disabled, a separate
application (CastleLink Graph Viewer) allows you to view the
downloaded data. The graph can get very "busy" with
all the parameters so even if you logged all the data, the
viewer allows you to remove it from the displayed graph. I
usually disable a bunch of the less important parameters before
I save a graph as a .jpg image for posting. The data logging
is saved in sessions (or ESC power-ups) and acts as a FIFO
(First In First Out) buffer that continuously wraps around.
As you can see from the screen image, a 5 sample/second rate
can log all the paramters for over 15 minutes without wrapping
Software tab reveals another one of the great features of
the Castle ESCs in that they can be reprogrammed for new firmware
right from the Web! I don't always upgrade to the latest beta
version because the changes are often for helis, not planes.
Further, if you have a problem with a newer version of beta
firmware, you can always revert back to an older version.
last help screen below shows the various ways to trip a low-voltage
cutoff. I often disable this on larger models because it has
been my experience that the planes will no longer fly before
you get to the "danger zone" on the LiPo cell voltage.
3.0v/cell reduces longevity, 3.2v/cell is fair, 3.4v/cell
is what I typically strive for as a minimum after a full flight.
During a full throttle pass, it is ok for the LiPo cell to
dip below 3v momentarily and then recover once throttled back.
You typically don't want your motor to cut out during this
period. With the voltage cutoff disabled, a performance plane
becomes noticeably wimpy when the voltage drops to 3.4v/cell.
The sensitivity of the voltage dip depends on many parameters
like pack capacity, C-rating, aggressiveness of setup, and
how long into the flight you perform the maneuver. In my Ultimate
setup, I don't think the 15AH capacity at 30C will have much
of a voltage dip so I initially used the default settings
of Auto-cutoff at 3.0v/cell.
help screens are seen from pressing the question mark in the
blue circle. For Current Limiting, you have 5 choices. I typically
leave mine at normal which is the default setting. Competitors
and demo pilots sometimes disable the current limit, after
they are comfortable with their setup parameters, so that
the ESC cannot shut down unexpectedly.
CastleLink application also detects when a new version of
PC software is available. It directs you to the Castle Creations
downloading page and upgrades the application seamlessly.
Castle currently has only a version for PCs but they are also
working on a version for the MAC.
Assembling a "Super Pack"
you assemble a super battery pack like this 12s3p 15AH configuration,
you must keep safety your first priority. I use safety goggles
when soldering and sanding with the Dremel tool. I also have
several fire extinguishers nearby.
test packs I used here for testing are similar but not matched
cells. I will likely purchase six 6s packs of the same type
before flying the plane.
soldered Castle Creations 6.5mm bullet connectors to all the
6s packs. These connectors are rated to 200 amps. The red
wire gets the male connector so that when using a single pack,
the last connection to the ESC can easily touch the anti-spark
resistor (soldered to the ESC female bullet) just before being
inserted. On this application, I am using a separate arming
switch and resistor so the male/female orientation is meant
for other smaller applications.
set of 6s packs are first balanced charged separately and
then connected in series to make a 12s pack. The resultant
three 12s packs are then connected in parallel to create the
super battery pack.
made my own 3:1 adapters using #10 Castle Creations "wet
noodle" silver wire. I don't know what the rating of
the HK 8mm bullet connectors is but they are more like 10mm
connectors so I expect them to be sufficient.
my test box, I have one #10 gauge wire coming from the arming
switch to the battery packs that I will eventually replace
with a #8 wire. For testing purposes, the #10 wire should
be sufficient. The Robot
MarketPlace sells high quality wire by the foot in many
gauges including #8.
charged the packs last week. No matter when they are charged,
you should measure each 12s configuration before connecting
them in parallel. I measured 49.8v, 50.0v and 49.9v so I knew
that I would have no issues when connecting them in parallel.
The resultant super pack voltage was 49.9v. The super pack
sits on a piece of 1/4" aircraft grade lite plywood and
is held by two Velcro (p/n 90700) One-Wrap straps. A similar
configuration will be used in the plane once I assemble the
connection of the bullet connectors is covered with a 1.5"
piece of masking tape. This is done for safety since there
is often a small ring of metal showing that the shrink tubing
doesn't cover. I also found a piece of EPS foam with the perfect
density to make some end caps for both the battery leads (when
separated) and the final two 8mm connectors. The red cap has
the EPS foam inside. The advantage of using the EPS foam is
that it will not press the male connector pins during storage
and has no memory for being slightly forced onto the connector.
They are inexpensive and can be made in seconds with a razor
knife and ruler. The EPS foam caps will not fall off or be
Testing the Power System
stated before, the reason I was testing the motor outside
the plane is because the Turnigy CA120-70 had no track record.
Once satisfied with its performance, we'll build the motor
box in the Ultimate and mount the motor. Assuming all works
well, it will be a relatively low-cost giant scale power system.
PJA Series Beechwood prop was purchased from Tower Hobbies.
These props are constructed of top-grade German beechwood
and balanced during every stage of production. I also bought
Prop Covers that work up to 34" props.
was surprised with the quality of this prop. It was perfectly
manufactured and painted with a clear coat enamel making it
an excellent value.
The DA100 (PDG-DA3W)
Drill Jig was ordered from PSP Manufacturing and arrived in
only a few days. I compared it with my Turnigy motor holes
and it was a perfect match. This drill jig comes with a bit,
washer, and holding screw. It can also be used for other DA
and 3W patterns as well.
friend, Paul Weigand, mounted the Xoar prop to the Turnigy
CA120-70 motor. He used the DA-100 drill guide (29mm centers)
but still needed to open the holes by .020" (0.5mm) for
a proper fit. This is typically required to properly align
the screws through the prop and washer.
won't bother with the spinner and backplate mounting until
I determine the prop size I want to use. The 42% Ultimate
comes with a nice aluminum backplate and white locking nylon
weather initially prevented me from doing a full power test
outside in my driveway but I decided to perform a low-RPM
test inside in my gym room. The test was very successful and
I was excited to try it again soon.
video below shows how easy it is to arm and disarm the power
system without a spark. The portable work bench is weighed
down in the back with a 75lb E-Z curl bar. My Spektrum transmitter
was turned on just prior to filming and I removed the Xoar
prop covers. In one of the low power checks, a framed photo
blew off the wall and hit the video camera stand on its way
down. The rubber flooring helped keep the glass from breaking.
Even at low RPMs, the thrust from the 30" prop was apparent.
wasn't much warmer on the following Sunday but at least the
sun was out. I thought it was 20 degrees but it was really
15 degrees with a single digit wind chill. It didn't stop
us as we proceeded to have the second motor test. My buddy,
Jeff, made a LiPo pack warmer from insulation bags used on
tropical fish. It kept the super pack from directly feeling
the single digit wind chill.
video below is both impressive for the power that this setup
can deliver and humorous as I kept having to put more weights
on the bench to keep it from tipping. I throttled up slowly
and kept an alert eye on the bench from a safe distance inside
the garage. We were amazed at the prop blast that was blowing
25 feet into the garage.
result summary is that while I obtained a 10.8KW power level,
I reached the limit of the Castle ICE HV 160 ESC as it tripped
the current limit at 260 amps. This is what it is designed
to do when set to "Normal" current limit. My goal
using this ESC is to obtain a power level closer to 9KW with
a current peak around 200-225 amps.
the video, I mentioned that I would try using a low timing
setting but after checking the current level on the data logging,
I realized that I needed to drop to an 11s3p configuration
if I still want to use my 30x10 prop. So this would be my
next test for the following weekend; stay with normal timing
and use an 11s3p setup.
also planned to beef up my motor test box and work bench as
the power level at 10,000 watts was impressive! In all my
electric conversions, I had never encountered this much power.
next testing session with an 11s3p 15AH LiPo was much better
and did not trip the current limit. Using the Xoar 30x10 prop,
the system produced runs of 7400 watts at 203 amps. The RPMs
went down to about 6050 at full throttle. I was running all
the default settings as shipped from the factory for the ICE
HV 160 ESC.
was prepared to change the timing, if needed, by bringing
the Castle Field Link Portable Programmer. It turned out that
we didn't need it as the ICE HV 160 can sustain 200 amp peak
draws without issue. It was a cold 10 degrees out which didn't
seem that bad without wind but the prop blast into the garage
was not fun. I added four metal brackets to the front corners
of the test box to help improve its integrity. We also tied
the top of the work bench to the garage door supports with
some Nylon rope. This kept the work bench from pulling forward
and eliminated the tipping. The weights were still used to
keep the test bench relatively heavy.
had no issues this time but my tachometer reading was incorrect.
The 7000 RPMs mentioned in the video was really from full
throttle on the 12s LiPo and not partial throttle on the 11s
testing. I am not sure why the reading was incorrect but the
pole count is indeed 24 poles.
this point I am happy with the motor performance so we will
move forward with building the motor box and finishing up
the cowl and spinner.
7400 watts will provide a 180w/lb power level on a 40lb plane.
My power system limitation right now is the ICE HV 160 ESC.
The Turnigy CA120-70 motor may be able to handle a higher
power level but we will not be sure until we see some flight
testing, measure the temperature, and test its longevity.
this setup makes for a relatively low-cost giant scale power
system. Since the peak current is only 200amps for 7400 watts,
when using a 30" prop on an 11s LiPo supply, a lighter
2p configuration could be used on smaller giant-scale models
in the 27% to 33% range. Alternatively, you can use a 12s
setup with a 27" prop for about 7000 watts at 169 amps.
World Models 42% Ultimate assembly begins with installing
the ailerons on all four wing halves.
manual says to replace the CA hinges with the supplied metal
ones. I didn't see any metal hinges in the kit, so I decided
to use Robart
Super Hinges. I have used these in the past on giant scale
projects as they come highly recommended.
of the 8 CA hinges was replaced with a Robart Super Hinge.
After first checking the fit and swing, I glued them in place
using BVM V-poxy
for a strong hold that won't weaken or yellow over time. Note
that each hinge was lightly sanded to help the glue hold and
then coated in the center area with Vasoline to prevent glue
from getting in the hinge.
installing the aileron servo and linkage, I covered the gap
on the bottom side with a strip of clear Monokote. In this
manner, the dust and dirt won't stick to the center and the
strip can't be seen from the top side.
hardware set that comes with the World Models 42% Ultimate
is pretty good. I have used this hardware on their other giant
scale models with great success and it adds to the value of
servo arm extension attached to the stock wheel of the Spektrum
servo without any modifications.
cutting away the covering over the inner servo bay (I'm using
a single servo per aileron), the servo mounted in place without
issue. I attached a 24" HD extension on the servo wire
which easily routed through the wing due to the pre-installed
hardwood block exists in the aileron where you need to drill
the hole for the horn. Each end of the control rod is threaded
for a clevis which is then attached to the bearings with a
screw and locknut. The horn covers are a nice added touch
giving the linkage a cleaner look.
more wings to go so repeat ad nauseam.
four wing halves were completed. Each wing was built like
the first one and had the aileron sealed on the bottom side
with clear Monokote. The supplied linkage hardware worked
I am using only 8 servos total for the entire plane, instead
of 16, I realize about a pound in weight savings.
Building a Giant - Cockpit
completing the second wing half, I needed a diversion so I
assembled the cockpit. Although the World Models 42% Ultimate
comes with a closed cockpit (which is much better than many
other giant scale open cockpits) the dash is left blank without
any decals. Further, the supplied pilot was actually only
a quarter-scale sized figure so it needed to be replaced.
detailed my Ultimate cockpit using the Aeroworks 150cc Ultimate
Instrument Panel and the Great Planes (GPMQ9006)
1/3 scale sport pilot. It isn't a perfectly scale size but
it was reasonable and well priced.
new Aeroworks Ultimate has a very different fuselage width
than the original World Models design so I needed to cut down
the instrument panel and then make a backing from black felt.
The result was a better detailed cockpit with little effort.
Building a Giant - Gear Mains
Ultimate was brought from my plane storage room to the back
room where I can complete the assembly. The gear mains came
next. After the metal brackets (for the flying wires) are
installed into recessed slots, the main gear bar is screwed
into place with the supplied cap head screws. Notice that
the t-nuts are offset so that you cannot install the mains
replaced the stock air-filled wheels with Dubro 5" Treaded
solid rubber wheels. The World Model air-filled wheels tend
to leak. The wheels are held in position on the axle with
a collar on each side.
discarded the supplied hardware for the pants and used my
own small cap head screws and t-nuts. After checking the alignment
of the pant, I drilled two holes through the metal gear mains
and through the pants. The pants are well designed and have
an indentation on both sides to mark where to drill the axle
hole. Since both of the inner sides have plywood plates fiber-glassed
into place, either pant can be used as either a left or right
pant. I used a Dremel tool to sand a Dime-sized recess on
the outer side where the pant meets the welded nut on the
the parts seemed solid when finished. I plan to add some extra
V-poxy to the hardwood mounts inside the plane that secure
the gear mains. This should help hold things together in the
event of a rough landing.
finished, I held the cowl in place with a single piece of
tape. The Ultimate was starting to shape up!
Building a Giant - Tail Section
installed the elevators in the two halves using the same techniques
used for the wings. The CA hinges were replaced with Robart
Super Hinges and the gap was sealed on the bottom with clear
Monokote. The stock hardware was used for the linkage. The
servo arm extension attached to the stock wheel of the Spektrum
A6030 servo without any modifications.
the two halves operate in opposite directions, I will connect
one to the elevator channel and mix in the AUX4 channel for
the other elevator. This also allows for easier electronic
trimming of the two surfaces.
prepared the tail for mounting the horizontal stabilizers
by trimming the covering on both sides. When you cut away
the rudder servo bay opening, it allows access to the control
line tubes. This is a nice feature on the World Models 42%
Ultimate to keep the long servo extensions secure. Now was
a good time to run the four long 48" servo extensions
through the tubes into the cockpit area. I'm using two servos
for the rudder for a dual push-pull configuration and two
servos for the elevator halves, one on each half.
stabs are held by a thick aluminum tube that is filled in
the center with wood. The center hole is for the servo control
lead and the front hole is for the alignment rod. It took
me a moment to figure out what the instructions meant. The
Ultimate has two set screws already mounted in the stabs,
one on top and one on the bottom of each stab. Using these
set screws, you can tighten them with a 1.5mm Allen wrench
and obtain a perfect alignment between the two stabs. They
are also used to adjust the incidence, up or down, as needed.
hold the stabilizers in place, one sheet metal screw and one
machine screw are used on the bottom side. Since there were
no holes pre-drilled, you can drill and tab where desired.
rudder was first glued to the vertical stabilizer using five
of the Robart Super Hinges. I drilled some holes in the tail
to allow the bottom two hinges to be glued in place without
cutting them shorter. The assembly was then glued to the fuselage
tail with V-poxy after first checking the fit and incidence.
that's an Ultimate rudder!
original 42% Ultimate was designed to use 4 servos in the
aft end of the fuselage for the rudder or a pull-pull configuration
to the center of the fuselage. For some reason, my model only
had three servo bays in the tail instead of four so I used
the two that were equal distance on both sides. Since the
servos were now mounted in the forward bays, the supplied
control rods were too short.
created some longer controls rods using Du-bro (#802) 4-40
by 12" Threaded Rods and then strengthened them using
some thick-walled carbon tubing that I had on hand. Since
the other end of the rod was not threaded, I replaced the
stock servo arms supplied in the kit with some Du-bro (#671)
Super Strength Servo Arms and used a Du-bro (#885) E/Z Link.
The threaded end of the rod used the stock clevis and connected
to the stock hardware on the rudder. I'll cover the E/Z Link
with some shrink tubing or a rubber keeper before flying.
tailwheel assembly (below) installed easily. It has a built-in
spring to absorb shock when landing. The spring links to the
rudder which allows the tailwheel to twist if it encounters
a rough surface.
wasn't happy with the supplied hardware for the tail wires
except for the anchors that mounted through the stabilizers.
I replaced the supplied steel cable, crimps, and wheel collars
with some Dubro and Great Planes 4-40 rigging hardware.
(#518) 4-40 Pull-Pull system
Du-bro (#618) 4-40 Rigging Couplers
Du-bro (#896) Crimps
Great Planes (GPMQ3795) 4-40 Threaded Steel Clevis
decided to make both ends adjustable for a symmetrical look.
In the photos, I have not yet added the rubber keepers to
the clevis. We used a crimp tool and triple feed through for
Building a Giant - Motor Box
temporarily taped the motor box together to see if my 12s3p
15AH pack would fit inside. I then measured the distance needed
to extend the Turnigy motor so that the the spinner backplate
mounted 1/8" from the cowl. It turned out to be about
4". However, we decided not to extend the motor on stand-offs
but rather extend the motor box to meet the motor and allow
more room for the packs to adjust the CG, if needed.
fuselage was then delivered to my friend, Paul Weigand, for
installing and modifying the motor box. Paul is an excellent
craftsman and had several good ideas on accessing the battery
pack from the cowl.
first step was to mount the cowl in position so that all the
decals lined up. Paul used the stock screws and rubber washers
for this step.
supplied backplate and spinner were mounted next. The backplate
came with a nice 10mm brass fitting that fit the Turnigy motor
shaft perfectly. The spinner cone needed to be cut for the
thick prop blades.
issue here is that the long spinner screw was meant for a
gas engine threaded hole on the shaft and there was nothing
to hold it on the Turnigy motor. Paul needed to make a new
prop washer that has a center hole tapped for the spinner
making the motor box extension, Paul needed to test the position
of the motor and backplate to the cowl before starting to
glue the box together. The only place he could stand it upright,
center the motor in the cowl, and, be able to work from above
it was in the stairway to his second floor. Now that is dedication
to precision work!
that the motor mount spacers are used to extend the CA120-70
motor to allow extra room for possible substitution in the
stock motor box has 1/16? aircraft ply doublers on each
side so it will be plenty strong. Paul also planed on fiber-glassing
the front corners of the box even though, it is drilled and
pegged. This will create a strong motor box that you can be
confident will stay together.
next step was to install the mounts for the cabane struts
because you can?t get to them once the bottom of the
motor box is in place.
slots for the cabane strut mounts were 1/8? closer together
than the motor box sides so Paul made up shims for each side.
He then tapped the motor box for 6-32 screws because they
now needed to be longer and then finally V-poxyied it all
also added some flooring to the motor box about 6? behind
the firewall in case all the batteries don?t need to
be far forward for the CG. The result is an 18? long
battery compartment to move them around in for the proper
4 holes drilled in the front of the cowl, behind the spinner
give access to the motor mounting bolts, with the cowl in
place. This allows you to check the mount on occasion and
tighten it, if needed.
alignment efforts can be seen with the spinner gap resulting
in a mere 3/32 of an inch!
completed motor box uses nylon tabs (old servo arms) to secure
the top. Paul's goal was to allow a battery change without
using any tools. The removable top and reinforcements accomplishes
this while keeping the box strong enough for 10000+ watts
six 5s 5AH packs and three 2s 5AH packs demonstrate that they
can reside all the way forward or all the way back. Once we
balance it, and decide where the packs should go, we'll make
foam inserts and use Velcro to keep them in place inside the
did a great job on creating a removable hatch on the cowl.
In this manner, the batteries can be easily accessed without
using any tools. Although you can barely see the lines in
the cowl, my plan was to add a large RCU globe vinyl-transfer
decal over the area. We'll see if I dare cover up this work
detail photos of the cowl above help show the hatch construction.
The foam blocks are used to aid in positioning the cowl when
mounting it. They keep the cowl from sliding further back
on the fuselage than wanted. Paul says that he did not glue
anything to the cowl before cutting the hatch opening and
added the framework afterward. The goal here is to retain
the slight curve of the hatch after it has been cut away,
so when gluing in the framework, be sure to not flatten the
holes in the front of the cowl allow you to make fine adjustments
to the motor position and then tighten it in place. This provides
a perfect alignment between the spinner backplate and the
cowl molding. Once the motor has been tightened, additional
nuts are placed on the ends of the screws behind the T-nuts
for double locking.
Building a Giant - Wired for Usability
ESC and arming switch mounted nice and easy on the new motor
box. I needed to only add an additional 8" piece of red
#8 Castle Creations wire to my existing test box setup. Note
the fiberglass on the pegged front corners on the motor box.
An added touch by Paul for reinforcement.
arming switch and anti-spark button will stick out of the
cowl bottom for easy and safe arming or disarming of the power
system. A single large wood screw was used to hold the arming
switch into the thick hard bottom wood of the fuselage. Since
the whole plane could be moved around by the arming switch,
I saw no need to make a mount for the other side. I secured
the large nuts with a dab of V-poxy.
first lightly sanding the side metal, the anti-spark button
is held in place with a little V-poxy.
main #8 red and black wires enter the motor box for easy connection
to the 11s3p Super Pack that will be strapped into place,
then further secured by Velcro and foam blocks.
an easy power upgrade from the $572 power system, only the
ESC and battery pack need be changed.
prepared the battery box for loading by cutting a piece of
light floor foam to form a barrier between the motor mount
screws and the super pack. If you haven't used this type of
foam before, I recommend buying some at a home improvement
store like Home Depot. I used it to line the floor of my R/C
trailer and it makes a great kneeling pad.
super pack is assembled outside the plane and then simply
set into place in the battery/motor box. I'll start with it
full forward when testing the CG. Once the desired location
is found, I plan to lock the bottom plywood plate of the super
pack in place much like Paul did with the hatches.
connecting the two disarmed super pack mains using the 8mm
bullet connectors, the battery/motor box top is secured in
the lower right photo, you'll see the yellow cabane mount
on the left which matches the Ultimate yellow quite well.
nice service of Home Depot is that you can take any piece
to them for instant color matching and buy a sample container
(7.25 fl. oz.) for only $3.
usually end up with a lifetime amount of paint, but the price
Building a Giant - Receiver and Servo
receivers and batteries certainly had plenty of room to be
spaced out properly. The receivers were oriented on different
axis and opposite sides of the aircraft. The two 3200mAh LiFe
packs weigh almost a pound and can be used to "fine tune"
the balance by sliding up or down the tray to the main super
that no matchboxes were needed and no Y-harnesses used. The
direct connection of each servo to the high-current fail-safe
receiver provides maximum power when needed without additional
used a mix for the rudder and elevator servos which allowed
me to fine tune both the trim and reduce the opposite forces
until the digital servos stopped "singing".
note that the receiver satellite wires run on top of the tray
and all the servo leads on the bottom. While this may not
be necessary, it can't hurt to help distance the wires to
reduce noise from the high-current servo leads.
On/Off switch is fail-safe and draws less than 1mA when in
the OFF position. This means that I can leave the receiver
batteries connected for over 6400 hours, which is plenty of
time to remember to disconnect them after a weekend of flying.
I'll mount the switch on the side of the fuselage.
Building a Giant - Final Assembly
properly mount the spinner, Paul made a custom washer that
was tapped in the center for the cone screw. A washer like
this may be available from Tru-Turn but the lack of photos
on their Web site makes it difficult to tell without calling.
also purchased some slightly longer prop screws because the
ones that came with the Turnigy CA120-70 motor were just a
bit short when using the Xoar prop and aluminum backplate.
first mounting the cowl, the motor position was slightly adjusted
so that the spinner backplate was perfectly centered. The
holes in the cowl allowed us to slightly loosen the motor
mount screws for the final adjustment. Once happy with the
alignment, we tightened up the motor mount screws and added
nuts behind the T-nuts to double lock the screws in place.
stock spinner for the World Models Ultimate is very good quality
and matches the color scheme. Note how the nylon cone piece
locks into the aluminum backplate so it cannot spin against
the prop. I needed to cut the spinner cone screw threads about
1/4" shorter for a proper fit.
last step of my cowl, prop, and spinner installation is to
put on the Xoar covers. The two covers are connected together
using the supplied hook and loop straps. The covers help protect
the prop and the people around it.
Ultimate is a fun plane to customize for your personal favorites,
so when the first of my custom decals arrived from RCU's,
Ken Isaac, I started adding some final details.
Sticker Shop has left and right hand vinyl decals in various
sizes with reasonable shipping rates.
canopy was lined with some (73305) silver 3M ScotchCal striping
tape to give it a touch of a framework. The pilot name decals
were compliments of RCU's Matt Kirsch and Ed Britton.
holding my super pack from the Velcro straps, it set right
down in place. I'll start with the pack all the way forward
when we do the initial CG check. There isn't much room for
the pack to slide around so securing it will be easy. Only
the two 8mm connections need to be joined and it is done while
the power is disconnected from the ESC.
installing the top of the motor/battery box, it is secured
in place with the four tabs made from servo arms.
cowl hatch is installed last. It gets secured by the two wooden
dowels in the front and the 90 degree twist latch. It doesn't
matter which way you turn the knob.
spark-free arming, the pushbutton and battery disconnect switch
are easily accessed from the left side of the plane.
control surfaces are so heavy that they tend to droop when
the power is not applied to the servos. Since I didn't want
them to bounce around in my trailer, I found that two sizes
of the plumber's pipe foam worked very well at keeping them
secured. Note that I mounted my failsafe receiver On/Off switch
just below the "A" in the AMP'D decal.
metal wing cabane and wooden cabin supports are installed
before attaching the main wings. The cabin supports were glued
in place to regain fuselage strength from the large removable
metal cabane parts were all labeled with stickers to match
the diagrams in the manual, making this an easy task. It appears
that the metal cabane cross-braces have been modified to improve
strength. They are much thicker than the manual photos and
required longer screws than supplied to hold them in place.
I used three longer M3 screws of my own.
nice feature of the World Models biplanes is the wing incidence
guides that come in the kit. I have used them before but these
are the biggest ones! The guides eliminate a good deal of
the measuring work needed for straight wings.
the hardware that I discarded for the tail wires, the hardware
that comes in the kit for the main wing cabanes and flying
wires is very nice. The posts snugly push through the cabanes
and are easily secured with clips. The posts will also host
the adjustable anchors for the flying wires.
the photos below, the lower wing was installed first. One side
gets the machine screw for removal from the tapped tube and
the other side is drilled for the sheet metal screw, once installed.
When the upper wing was installed, I used the wing incidence
guides to hold it in place so it didn't move around until the
cabanes were installed. My "giant" was almost ready
to fly! A future issue of AMP'D will cover giant-scale electric
flying with considerations for high-capacity charging at the
you're an NCIS fan, you may have wondered how Gibbs got
the boat out of his basement. Although my situation is similar,
I have the advantage of removing the wings.
adapting positively to technology and globalization changes,
the benefits can be used to attract more R/Cers into giant-scale
electrics. We often find new choices in our hobby that simply
didn't exist the year before and can suddenly be within
our budget for exciting new projects.
lower-cost power system for giant-scale electrics that utilizes
safe voltage levels can open up existing sectors of the
market that were previously hampered by cost, complexity,
cost comparison of the power system used in this column
with a few existing gas-powered alternatives reveals an
interesting paradigm shift.
Turnigy CA120-70 motor - $300
Castle Creations ICE HV 160 ESC - $272
DA-100 Engine: $999.00
DA-100 Muffler Set: $145.00
DA-120 Engine: $$1199.00
DA-120 Stock Mufflers: $160.00
3W-110iB2-F Classic Series $1195.00
Fuel sources for electric power have also dropped in price
dramatically in the past year. A typical 5-cell 5AH pack
is about $50 with as little as 1 cent shipping from on-continent
the past, many R/Cers just didn't have the budget for giant
scale projects. Perhaps this will change soon...
you fly electric, fly clean, fly quiet, and fly safe!
Special thanks for contributions
"Papa Jeff" Ring and Paul Weigand
section of AMP'D covers some of the questions that our
readers have sent in and I thought would be interesting
how is it possible that you draw so much current
over a #12 wire gauge in R/C when it is not rated
American standards are for house wiring that use
120v to 240v on 1000' length of copper wire to
determine the gauge. Our R/C applications use
much shorter lengths of silver wire which has
even less resistance than copper wire. The length
used is typically a short 12" or less.
Size Calculator shows that you can use #12
wire for 120 volts at 800 amps if you keep the
length to a foot. At 1000 amps, you need #10 wire
for a 12" length. This Continuity
Test Resistance Calculator shows a 0.001 ohm
resistance for 12" length of copper wire,
and silver wire would be even less resistance.
real capacity of a wire is actually best measured
in watts, not amperage, because a watt is a unit
of power that is a combination of amperage and
voltage flowing through the wire. Watts measure
the amount of power a wire can safely dissipate
without getting too hot. In other words, the wire
resistance has power loss which forms heat. Since
most wire charts are done in amps, it is assumed
to be at a single voltage level like 110v or 240v,
which is fine because the chart has an assumed
example, a chart for amperage ratings of various
sized wires used on 110V AC house wiring is very
different from a common 12v DC automotive usage.
The chart like the one above represents a typical
"max capacity" for an unknown length
of wire. Although a 1000' length may be used in
a home, it is much too long for automotive applications.
Likewise, the lengths used in automobiles are
too long for our R/C applications.
the shorter lengths and lower voltages used in
R/C make it possible to pass some heavy current.
I hope this helps you see how we can draw such
higher currents through very short #12, #10, and