Kit with hardware
Great ARF value and looks
Superb Covering &
Wheels Leak Air
Scale Clipped Wing Cub
World Models has created the first third scale clipped wing Cub
ARF. It comes in three different star burst color schemes and
is an aerobatic version of their classic yellow Piper J-3 Cub.
The clipped wing Cub and spare parts are available from Airborne
review will use new products for an electric conversion that delivers
6000 watts of power with a safe spark-free enabling feature.
Wing Span: 120 in / 3050 mm
Wing Area: 2402 sq in / 155 sq dm
Flying Weight: 27.5 lbs / 12500 g
Fuselage Length: 91.5 in / 2330 mm
Engine Required: 80cc gasoline engine
Radio Required: 4-channel radio w/ 6 servos
Top quality balsa and plywood construction
Covered with hand iron-on World Models' ToughLon coverings
Pre-painted fiberglass cowling
Detachable main wing using dual aileron servos
Comes with all hardware and accessories
The 1/3 scale Clipped Wing Cub arrived via Greyhound Transport Services.
My initial inspection showed no damage and I found all the hinges to
be pre-installed. The covering was beautiful! As you can see from the
yard stick next to the horizontal stabilizer, my initial thought was
that this model may need to be built in the garage.
ARF includes a manual, finishing decals, plastic manifolds, and a painted
pilot with mounting deck and hardware.
unwrapped most of the parts for easier viewing. The pre-painted fiberglass
cowl is fully protected in shipping and the transparent dummy cowling
can be used to aid in cutting holes for engine and exhaust pipe protrusions.
For my electric conversion, I will be adding several air flow holes
wing rods are used to connect the wing halves through the fuselage.
I liked the pre-assembled tailwheel which had built-in shock absorption.
As usual, the little hardware packets are all numbered to match the
diagrams in the manual. This makes it real easy to find the right set
of hardware for each step of assembly. A nice touch by World Models!
A closer look at the fuselage reveals quality construction and excellent
lightening techniques. The right side of the fuselage has a double door
that opens half up and half down. The fuselage nose and cowl measure
7-3/4" wide and 9" high.
motor in my electric conversion review is the new XTRM 7050/06
from Hang-It R/C. At only $335, this cutting edge power comes
at a cutting edge price!
XTRM 7050/06 is a 176 KV Brushless Outrunner with a current capacity
of 150 amps continuous and up to 240 amps at 30 second bursts.
It is meant for aerobatic and 3D models weighing 25-50 lbs. It
offers a maximum efficiency of 90%, a no load current @ 10vdc
of 2.8 amps, and, an internal resistance of 15 Mohms. This outrunner
has a 10mm shaft and is designed to run on 10-15 LiPo cells. A
30x12 prop on 10 cells for large scale models or a 28x10 on 12
cells is great for extreme aerobatic flying. The price includes
a bolt on prop adapter. The motor weighs in at 3.7 pounds.
My favorite part of many glow to electric conversions is the
motor mounting scheme. With this new motor, I could not find
a mount large enough to work properly so I made my usual trip
to Home Depot for a look around.
decided to create a galvanized steel box using two inexpensive
4x4 post caps. The Simpson BC40Z 4x4 CAP Strong-Ties cost only
$3.12 at Home Depot. Each 4x4 CAP weighs 5.6oz. I also needed
a small block of 3/4" hard wood to extend the motor further
and also allow easier drilling of the 1" hole used to clear
the motor shaft collar.
motor mounting holes are 5cm apart across the diameter and 3.5cm
to each adjacent hole. The threaded mounting holes are 6mm.
I used the following hardware items to assemble my box and mount
- BC40Z 4x4 CAP Simpson Strong-Ties
4 - 6mm x 30mm Cap Screw Sockets
4 - 1/4" x 1-1/2" Cap Screw Sockets
4 - 1/4" T-Nuts
8pcs - #10-32 x 3/8" Slotted screws and nuts
second 4x4 CAP was screwed to the firewall using shorter 1/2"
1/4-20 socket heads screws into the t-nuts. To help hold it
secure, I added plenty of Pacer Z-42 Thread Locker to the screw
threads before tightening them down hard. The motor was then
easily mounted to the firewall using eight #10-32 x 3/8"
slotted screws and nuts; 4 per side.
to the high current of this power system, I will connect each
of the three motor wires to the ESC using a whole Dean's Ultra
connector (or both pins) per wire.
cowl opening was enlarged a bit using a Dremel sander to allow
the massive prop adapter to protrude without rubbing. The cowl
was then mounted using the supplied rubber grommets and screws
in the kit.
used a PE26015E
APC 26x15 e-prop from Hobby Lobby. For a size comparison, I
put it next to a tiny U80 prop.
motor installation was clean and solid. If there are any signs
of side-to-side weakness, I can easily press a 2x4 wood piece
in the middle of the mount and secure it with screws. I may
also add a TruTurn TTH-1500-B-CUB
hub to the nose for an added scale look.
6000 watt power system will make use of the new Jeti
Opto 200-amp controller from Hobby Lobby.
high voltage battery packs are required for your aircraft it
is necessary to use an "Opto" controller. Opto controllers
do not have a BEC (battery eliminator circuit) to power your
radio receiver and servos. A separate power supply is required
like either a 4.8v - 6v standard receiver battery or a UBEC
(KFS001 - KFS003). A UBEC is a device that regulates high voltage
from your flight batteries and supplies power at a voltage suitable
to run your receiver and servos. SPIN Opto controllers are programmed
either with your transmitter or with the "SPIN BOX",
just like the regular SPIN controllers. The SPIN Opto controllers
have a dedicated programming plug that simplifies program setup
and data retrieval.
Jeti SPIN200 ESC costs about $550. and weighs 270 grams (9-1/2
oz.). It can handle a 24-40 cell NiMH/NiCd pack or a 6-14 cell
LiPo pack. The SPIN200 uses two sets of 4mm power input cables
(2 for positive and 2 for negative) and has 4mm output cables
to the motor. Due to the high voltage supply, the SPIN200 has
an ancillary circuit that prevents sparking when the controller
is being connected to the flight batteries. The negative poles
of the flight pack must be plugged to the two 4mm black wires
first, then the thin (1.5mm) red wire must be plugged into the
positive side of the flight pack. Only then can the two 4mm
red wires be plugged into the flight pack. The controller has
two 2-1/2"x2-1/2"x3/16" heat sinks and four standoff
mounts to allow free airflow around all sides of the unit.
SPIN BOX Programming Control not only programs your
SPIN controller, it is also a powerful testing tool!
When the SPIN BOX is connected to a Jeti SPIN controller,
it allows you to custom program your SPIN controller
and provides a readout screen for the data that is stored
in the SPIN controller after a flight. It is simple
and intuitive to use. You will not need to drag a huge
set of instructions or a computer to the flying field
When the Jeti SPIN Box is not connected to a Jeti SPIN Controller,
it can be used by itself as a powerful testing tool:
Measure receiver channel output pulse widths.
Measure servo transfer speeds, either unloaded or in actual
use in the aircraft.
Servo pulse generator, center your servos without receiver
Servo-cycler, check the function of your servos, from 10 to
controller setup allows you to select the type of aircraft from
the menu on the "SPIN BOX", and timing, brake, etc.,
will be set automatically.
controller setup gives you the complete freedom to program the
Timing: 0 to 30 degrees in 1 degree steps for any brushless
Acceleration: for how quickly the motor reaches full power.
Braking: can be set Off or On with selection of hardness.
Helicopter constant RPM: can be set for minimum and maximum
rotor head RPM and how quickly the controller reacts to changes
in RPM under load.
Battery type: and number of cells can be picked as well as
the per cell cutoff voltage. Choose either Hard or Soft slow
down at cutoff voltage.
Motor rotation: can be reversed from the controller. which
is great for motor systems where access to the motor/speed
controller is difficult.
SPIN BOX data logging feature means that you will never need
to bench test again! After a flight, just plug the SPIN Controller
into the SPIN Box and read out the following in-flight data:
Maximum and Minimum temperature of controller during operation
and the time it occurred.
Maximum and Minimum current at full throttle, the time this
occurred and the voltage of the flight batteries at that time.
A huge help in selecting the ideal propeller for your airplane.
Cut-off voltage and the time that this occurred.
Motor run time measured from the first revolution.
Maximum Motor RPM is recorded and the time it occurred.
Errors where control parameters have been exceeded are recorded;
this is a big help in determining the causes of motor cut-offs.
the SPIN Controller:
Jeti SPIN200 ESC comes with large bullet connectors and mates
for the motor. It also comes with standoffs and screws for easy
mounting to the firewall. The SPINbox comes with a special servo
connector for stand-alone testing with a receiver output.
prepared the ESC with the bullet connectors and a single Dean's
Ultra connector on the plus and minus wires. I also replaced the
Dean's Ultra connectors on the motor with the bullet connector
ESC mounted easily to the firewall. Holes were drilled in the
firewall to run the wires into the fuselage. I plan to cut holes
in the cowl to force air over the motor and down across the ESC
before exiting. The third spark eliminator wire was extended and
run into the fuselage. It will be connected to an On/Off switch
before enabling the main 14s 10AH pack.
I cannot find a product I need for electric flight, or the product
is more expensive than expected, I often go outside the R/C
industry to look for what I need to get the job done. My inexpensive
motor mount using 4x4 CAP ties is an example of this situation.
situation like this arose with enabling a 200amp power system.
I had a motor and controller that can draw up to 200 amps but
no product to help me properly arm the system. I discovered
that Battery Disconnect Switches were a common product in motorcycle
racing, RVs, and campers.
100amp to 500amp "Little Switch" from Flaming River
Industries is available in a simple switch-only form for $20
or with mounting plate, hardware, and rubber seals for $28.
I purchased mine from a known good source like Summit
my application, the mounting plate was not needed. The rubber
cover is really meant to keep the switch clean in racing environments
where oil, fuel, or dirt can more easily come in contact with
the switch. To keep the switch from protruding too far, I made
a thick washer from the foam flooring I used to line my trailer
floor. These flooring pieces can be purchased at most home improvement
stores and cut easily with a razor knife.
heavy duty toggle switch from Radio Shack was not really needed,
but at the time, I had no specs for the anti-spark line requirements.
It is possible to use a standard receiver On/Off slide switch
as there is only a slow charge through a 100 ohm resistor in
the Jeti controller.
procedure to arm my power system is to first throw the anti-spark
toggle switch and a few seconds later insert the removable key
and turn it to arm the system. This also locks the key in place
for the flight. I plan to use a separate 2-cell Lithium pack
and regulator to power the receiver and servos.
made a power distribution diagram for my combination of 5AH
Lithium packs that will make up the 14s 10AH total battery supply.
The distribution board will be wired from #12 wires and Dean's
beefed up series/parallel connector will allow me to connect
3 pairs of 5AH packs in series for my 14s 10AH supply. I mounted
it to a plywood former in the Cub after gluing a corner piece
in with epoxy for added support.
Spektrum AR7000 receiver mounted cleanly. I am using an FMA
Force Regulator for a 6v supply at 10amps for the servos
and receiver. It will be fed by a FlightPower 2-cell 7.4v 3000mAh
sizing up the 1/3 scale Cub, I decided that I could assemble it
in my back Family Room where it could stay in various stages of
assembly without being in the way. The horizontal and vertical
stabilizers come already prepared to install. All you need to
do is cut away the covering from the fuselage tail and remove
the two hardwood pieces used to support it during manufacturing
first test fit the stabilizers without using any glue. They fit
perfectly and I discovered that the vertical stabilizer is locked
in place much like a puzzle piece. After gluing the horizontal
stabilizer with 5-minute epoxy, I decided to glue the vertical
stabilizer with Aileen's Tacky White Craft glue. Note that the
white lines along the stabilizer and fuselage joint will turn
clear when the glue dries. The white glue makes for a cleaner
looking joint when you have the time to let it dry overnight.
wing halves were temporarily installed to check the fit as well
as the incidence with the stabilizers. Everything fit great and
aligned properly without the need for any changes. The wings use
two aluminum bars that push through the fuselage top.
gear mains installed without issue. The wheels are held by two
collars which end up hidden for a clean look. The tires can be
inflated using a normal air pump stem. The metal bars for the
wing struts are also installed at this time. They are held secure
by one machine screw into a t-nut and one wood screw into the
tailwheel assembly has a built-in spring to absorb shock on landings.
I found that the flat spot on the shaft was a bit off center so
I corrected it with a Dremel tool sanding disk.
36" long servo extensions for the two elevator servos and
rudder servo were first tied with Fireline (carbon fishing line)
and then shrink wrapped to keep them secure.
supplied threaded control rods, clevises, control horns, and hardware
all seemed to install easily and fit well. I used HD servo arms
on my digital servos in the tail. The two elevator servos were
Hitec HS-5645MG and the rudder servo was a Spectrum DS821 Digital
Sport Servo. These were servos that I had on hand but you could
use any good high torque digital servo. The clevis is held to
the servo arm with a supplied machine screw and nylock nut.
The windows installed easily using BOND 527 Multi-Purpose Cement
from my local hobby shop. The windshield is held in place using
the four supplied screws and rubber spacers to protect it from
cracking. The pilot comes pre-painted but I added a mustache.
The pilot mount comes pre-cut as does the black balsa base.
Dubro wheels are solid and can be drilled to the needed 1/4"
I had difficulty keeping air in the inflatable tires from World
Models. I suspected that I may have had a bad set so Airborne
Models was nice enough to send me a second set. Unfortunately,
these tires also had problems holding air so I set them aside
and replaced them with Dubro (500TL) 5" Treaded Lightweight
I then discovered that Dubro makes Cub
Wheels in 1/5, 1/4, and 1/3 scale sizes. The 1/3 size wheel
mounts right on the 1/4" diameter gear rod. Instead of using
the supplied yellow Cub Hub Caps that came with the Dubro wheels,
I cut the hubs from the World Models kit down to size for a better
The aileron linkage installed as easy as the tail linkage. The
control horn hole is marked by a pinhole in the aileron covering.
I used JR DS8611 Ultra Torque digital servos which will help me
perform aerobatics with the clipped wing design of the Cub. I
replaced the stock servo arm with Dubro (#671) Super Strength
Long servo arms.
wing struts installed without issue and all the hardware was supplied.
Each wing half contains 4 pre-installed t-nuts to receive the
screws that hold the strut. The t-nut positions are marked by
pinholes in the covering so they are easy to find.
the landing gear installed, the Cub could now be wheeled around.
I decided to test the fit in my trailer and bring it to a local
R/C show. The wings press on easily to the two aluminum bars
and the Clipped Wing Cub covering scheme really looks great!
large tail is braced on all 4 quadrants. The kit includes
all the hardware needed and the tail is pre-drilled with metal
sleeves in place. To help find the covered holes, I positioned
a flashlight on the opposite side before cutting the holes
open with a razor knife.
wing halves are mounted using two aluminum tubes. One side is
secured with removable machine screws and the other side with
more permanent sheet metal screws. The holes in the wing and in
the tubes are pre-drilled and tapped for the machine screws. Optionally,
you can use machine screws on both ends, if you desire.
replaced the hardware that secures the struts with a 3/8"
Hitch Pin Clip from Home Depot. Holes were drilled in some brass
screws to secure the strut and retain the clip. The clips are
easily removable and make for a quick setup in the field.
painted the manifold caps and added some air cooling for the motor
and ESC. The manifolds and valve covers were painted black and
silver and then glued to the cowl with Pacer Poly-Zap. The areas
that were glued were first roughed a bit with sandpaper. I added
an opening in the front for cooling air flow to enter and a larger
rectangular opening for the air to exit the bottom of the cowl.
To help direct the air flow, a 1/4" wide flap was bent toward
When the Cub is "loaded with Lithium", the motor is
powered by FlightPower
EVO25 5000mAh Lipo packs. The 25C continuous packs can deliver
250amps continuous in my paralleled 10AH configuration so I won't
be stressing them with my planned 200amp maximum burst setup.
2-cell 3000mAh EVO-RX pack is a safe independent supply for my
receivers and servos. The 20C, 7.4v pack can deliver 60amps continuous
to the FMA Power Force Regulator. The clean linear regulator output
provides 6v at up to 10amps continuous. This supply to the digital
servos is more than what is needed so there will be no load lag
on the control surfaces. Note that the dual wire and connector
set from the EVO-RX pack allows it to provide more burst current
to the servos when needed. I plan to replace the dual connectors
with a single Dean's Ultra connector to mate with the Power Force
I decided to ground test everything in my backyard and check the
CG before taking the Cub to the flying field. The CG is suppose
to be about 6" behind the leading edge measured at where
the wing meets the fuselage. I marked the underside of the wing
tips so that two people could lift the Cub at the appropriate
balance point. My Cub was a bit nose heavy which will be fine
for the initial flight. I measured 87.5 amps on one of the paralleled
packs which means my current flow is 175 amps near full throttle.
This provides 175amps * 14 cells * 3.4v per cell =8300 watts or
11h.p. which is 2300 watts over my target 6000 watts.
needed to either reduce my prop size or cell count to approach
my goal. Either way, the XTRM 7050/06 from Hang-It
R/C has tremendous power!
friend, Paul Weigand, made a spinner hub similar to the TruTurn
It really gives the nose an added scale look. We made a short
video showing the power test and some taxi turns in my backyard.
Testing Video (2meg)
Our "Chamber of Commerce" day finally arrived on the
first weekend in November. A plane this size requires a team
to help assemble as well as document the results through photos
and video. My pilot for the test flight was Ron McGrath, the
father of Team JR's Devin McGrath. Ron has several decades of
had to drop the cell count down to 12s in order to obtain a
reasonable power output level. I measured 156 amps which provided
a full throttle power level of 6700 watts. This was much more
power than needed and everything was well within specification.
Dubro Cub wheels looked great and all the control surfaces were
checked out. We range checked the Spectrum receiver using the
convenient button on the back of the transmitter while walking
several hundred feet away.
discussed the flight plan with Ron and we were ready to go...
Cub took off with only 1/3 throttle and the tail lifted without
any elevator offset. No trimming was needed so we flew it around
for a while to test the maneuverability. It was very stabile
in flight right from the take-off.
Cub had much more power than needed so most of the 12 minute
flight was under 1/3 throttle. It could loop and roll without
issue. Our rolls (in the video) used rudder compensation but
did not have any differential set up. The 10AH 12s battery pack
was only 50% discharged upon landing.
Cub landed gently with and without power applied. In the maiden
flight video, we landed after a few minutes to adjust the throttle
trim. This allowed the prop to stay spinning as it eliminated
the dead zone and gave the pilot finer control. Although we had
no issues with the Cub performance, something bad happened and
we were forced to land after 12 minutes. The big 1/3 scale Cub
was safe on the ground.
Ron and I walked back to the pit area, we discussed what happened
to the motor that caused the flight to end. It turns out that
several magnets had broken free, causing the motor to completely
seize up. Fortunately, the Cub wingloading was so light that it
didn't require any motor power to land. It was safe on the ground.
reported the issue to Hang-It RC and they immediately took the
7050 off their Web site. I felt this was a very responsible move
on their part and they conveyed that they were very concerned
about the motor issue, yet happy that no damage occurred to my
have since reported that after speaking with the manufacturer,
the 7050 is already undergoing changes to assure this doesn't
happen in the future. The motor will now have a new casing (housing)
to better support the magnets at each end. They are also looking
into filling the gaps between the magnets with resin for additional
support. When Hang-It RC releases the upgraded motor, the Cub
will be back in the air for the next flying season.
3000-4000 watts is plenty of power to fly aerobatic maneuvers
with the third scale Cub, a suggestion for another usable setup
is the AXI / Jeti power system shown on the right.
only thing I found on this third scale Cub that I didn't like
was the wheels that leaked air. These were easily replaced with
a set of scale Cub wheels from Dubro.
World Models kit is very complete and includes all the hardware
needed in individual bags that are marked to match the assembly
step number. This third scale Cub is a great value because it
is highly pre-assembled and beautifully covered. The flying performance
is simply superb!
100 West 1st Street
Deer Park, Texas 77536
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.