|Contributed by: Greg Covey | Published: October 2006 | Views: 73331 | Email this Article
by: Greg Covey
Photos: Greg Covey
Photos: Papa Jeff Ring
1 & 3 Pilot: Lynn
2 Pilot: Scott Miller
Distributed Exclusively in the U.S.A. by:
Horizon Hobby, Inc
4105 Fieldstone Road
Champaign, IL 61822
Ph: (800) 338-4639
Toll Free: (800) 338-4639
Fax: (217) 352-6799
Kit with hardware
Great ARF value and looks
Superb Flying Performance
Magnetic Held Hatch
Matched Power 25 Outrunner
J3 Cub 25 Introduction
E-flite J-3 Cub 25 ARF from Horizon Hobby has great scale appearance
and performance which include scale ailerons. The ARF model is
built from quality balsa and light ply construction making for
a sturdy, lightweight airframe that handles incredibly well in
most any flying situation. The firewall is set up for use with
an outrunner motor, such as E-flite?s Power 25, making a
perfect power match for the airframe. Optional floats add a new
dimension to the scale flying experience, and the one-piece wing
allows for easy transportation to and from virtually any flying
field, pond or lake. The model can be flown with either a 10-cell
NiCd/NiMH pack or 3-cell Lithium pack.
Wing Span: 62 inches (1575 mm)
Overall Length: 35.5 inches (900 mm)
Flying Weight: 4.0 - 4.25 lbs (1.8 - 1.9 kg)
Motor Size: Recommended: E-flite Power 25 Outrunner (EFLM4025A)
- not included
Radio: Minimum Requried: 4 channels - not included
Servos: Required: 4 Mini Servos - not included Recommended:
4 JR Sport MN-48 (JSP20040)
Trim Scheme Colors: UltraCote Cub Yellow (HANU884) & Black
Prop Size: 12x6E
Speed Control : Required: 40 amp brushless Recommended: E-flite
40A brushless (EFLA312B)
Recommended Battery: E-flite 10-cell 12V 1800mAh Ni-MH (EFLB4010)
or Thunder Power 3-cell 4200mAh Li-Po (THP42003S2PPL) - not
Outstanding scale detail, including the factory-painted fiberglass
cowl with molded engine detail
Scale aileron design sets the E-flite J-3 Cub apart from other
25-size electric Cubs on the market
E-flite's optional 25-size floats are easy to assemble and attach
to the J-3 Cub, and offer thrilling performance during water
taxi and take-off
Built-in float mounts
Removable one-piece wing for fast transition to the flying field
Factory-painted landing gear with authentic Cub wheel caps
Quality balsa and light-ply construction, and genuine Ultracoat
Outrunner-ready firewall?perfect match for E-flite?s
Power 25 Outrunner, 870 Kv
Flies great with LiPo (THP42003S2PPL) or Ni-MH (EFLB4010) packs
Cub 25 came very well packaged and each part was individually wrapped
The covering looked great and the 51 page manual was very well written
with plenty of photos.
the Cub came already trimmed with decals, the kit provides an extra
sheet for the various brand names.
the individual plastic bags and found the control surfaces were taped
to their respective part of the plane.
was already painted and looked great!
fuselage was well built; being both strong and light. The motor mounting
holes, control rod tubing, and, air-cooling system were already done.
The front bottom hatch is held in place with pre-mounted magnets for
easy battery access.
the E-flite 40A brushless (EFLA312B) ESC and there a warning note about
the BEC having an overload at very high temperatures when using higher-current
servos. Note that the ESC comes with mating connectors and wire extensions
for the motor.
have found during continued flight testing, the possibility of
a rx/servo current overload to the BEC in the speed control, causing
the motor and radio to shut down in flight. This has typically
happened on extreme high temperature days with continuous extreme
flight control inputs. Most speed controls on the market today
are designed for use with 4 sub-micro servos with relatively low
current draw like the E-flite S75. The newer sub-micro digital
servos, as well as most micro and mini servos, have a higher current
draw and can cause a BEC to shut down due to high temperatures.
order to provide the most reliable product, E-flite recommends
the use of a separate BEC (like the Ultimate BEC), or receiver
pack and switch using the following items to ensure trouble-free
- (EXRB100) Expert 720mAh NiMH 4.8v Receiver Battery
- (EXRA050) Expert Standard Switch
these items to power the receiver and servos after disabling the
BEC on the ESC. E-flite does NOT recommend using the speed controller's
BEC in the applications described above.
I'm using the recommended JR Sport MN-48 servos (JSP20040) and
E-flite Power 25 Outrunner (EFLM4025A) ...when it arrives.
two recommended battery packs are the E-flite 10-cell, 1800mAh
NiMH (EFLB4010) or ThunderPower 3-cell, 4200mAh LiPo (THP42003S2PPL)
pack. Although both packs weigh a similar amount, the power
density of the Lithium pack is doubled over the NiMH pack which
doubles for your flight time for about 4 times the cost.
Just after testing the J3 Cub 25 on wheels, I'll try out the
optional E-flite 25-Size Fiberglass ARF Floats (EFLA500). The
E-flite quick-mount floats are designed specifically for 25-size
planes that are float-ready out of the box, so you can go from
pavement to pond in just minutes.
Assembly starts by mounting the gear mains with 4 straps and 8
screws into pre-drilled holes. The gear mains fit snuggly into
channels in the bottom of the fuselage. An innovative wheel design
hides the collar and 4 screws inside for a very clean look. The
plastic Cub cap covers the assembly.
landing gear fairings are secured with 3 tywraps.
JR Sport MN-48 mini servos fit perfectly into the bay openings.
I am using an M5 v2 receiver in my J3 cub 25 for glitch-free
Alternatively, the Encore receiver provides the same glitch-free
performance but allows for the 5th channel to be re-programmed
for channel 5 or 6 in case flaps are used.
used ZAP Thin CA to glue the hinges in place. Remember not to
use CA accelerator (or kicker) here as we want the CA to soak
into the hinge material and balsa.
The JR mini servo mounted to the hatch plate using two supplied
blocks. All the hardware needed for this procedure is supplied
in the kit.
The E-flite manual is extremely detailed so I will be glossing
over many areas clearly covered in the manual. One area not
covered is that you will need 12" extensions for the aileron
wing joiner is made from two thinner pieces of plywood glued together
with epoxy and then glued into one wing half. After first test
fitting the wing halfs, they are glued together with epoxy.
two aileron servos must be connected together with a "Y"
adapter or an FMA 605SB Servo Buffer.
mounted the On/Off switch in-line with the black stripe to keep
it from detracting from the scale look of the Cub. You can either
re-route the ESC's throttle signal pin into the output of the
switch wire connected to the receiver or use the receiver battery
pack option. The On/Off switch provides added safety and convenience
when connecting the battery pack or finishing a flight.
that some vendors now sell On/Off switches for electric planes
that route all 3 wires eliminating the need to re-route the
ESC's throttle signal wire. One example is the 1570
Universal ESC Control Switch from MPI.
stabilizers were attached with 5-minute Z-poxy after first cutting
away the section of covering to be glued. I checked the incidences
and needed no offset for creating a perfect alignment. The tail
wheel assembly is glued in place before attaching the rudder.
The linkages installed without issue. The two elevator half
pushrods are combined using two wheel collars which are then
secured with epoxy after alignment. Note that I added a white
spacer to center the tail wheel and used a toothpick with a
dab of CA for a strain relief on the antenna wire.
The windshield comes pre-trimed and painted so you just need
to prepare the surfaces to be glued with a little sanding. The
side windows must be cut with a 1/16" border before gluing.
I used Pacer PolyZAP glue which is designed to work on plastics,
nylon, and, rubber. It is ideal for clear canopies and windows.
Attaching the struts is as easy as screwing them into the pre-drilled
holes in the fusleage and wing.
E-flite 25 motor comes with the motor mount, collet prop adapter,
connector mates, hex wrenches, and all hardware needed. Likewise,
the E-flite 40-amp Brushless ESC also comes with the connector
mates. Both these E-flite products come with mating connectors
and they each have their own connectors already soldered on.
You only need to screw in the X-type mounting bracket and solder
on a mating connector for the ESC-to-battery connection.
also received an Expert (EXRB100) 4-cell, 4.8v, 720mAh AAA NiMH
receiver pack to eliminate the need for the BEC feature on my
ESC. This is used in conjunction with the Expert (EXRA050) Standard
Switch with charging cord so you recharge it right in the plane.
was a bit dissapointed when I discovered that the pre-mounted
t-nuts in the J3 Cub 25 were a different size than the included
hex screws that came with the motor. Although the matching screws
for the pre-mounted t-nuts came with the J3 Cub kit, they were
too large for the X mount holes requiring you to drill them
out. This makes for lots of metal fragments so it is best to
drill the holes out before you attach the X mount to the motor.
Horizon Hobby has said that this mismatch in size between the
Power 25 motor screws and the J3 Cub 25 pre-mounted t-nuts is
already resolved so your model will likely not need this modification.
E-flite 25 motor attaches to the pre-mounted t-nuts in the
firewall. Remember to use some thread locker on these screws
as well as the screws holding the X-mount to the motor. I
decided not to mount the ESC to the side wall with Velcro
(hook and loop) as it is held in position quite well by the
thick wires and battery pack. We'll see if this works out
during actual use.
cowl was held in place while I drilled pilot holes for the 4
mounting screws. Some folks like to use masking tape to temporarily
hold the cowl in position while drilling.
prop adapter is designed to fit the APC 12x6 e-prop perfectly
without and bushing. The collet design simply presses in place
and is then tightened. I use the largest size hex wrench that
will fit through the hole in the spinner to tighten it.
I charged the ThunderPower 4200mAh pack with a Cellpro
4s Balancing Charger and ThunderPower to Cellpro Adapter
from FMA Direct. All three products are available from Horizon
this charger can safely recharge the pack in the plane, I mounted
the battery with Velcro on the bottom and two Velcro straps.
This combination holds the 10oz pack securely in place without
any sliding. Note that the fuselage hatch is held in place by
two strong magnets.
at the field is plug and play easy without having to remove
the wing or unscrew a hatch.
10-cell E-flite 1800mAh 4/5A NiMH pack mounts in the same manner
as the optional LiPo pack. It adds another 3oz to the flying weight.
Expert (EXRB100) 4-cell, 4.8v, 720mAh AAA NiMH receiver pack adds
another 2oz and is best mounted across the CG as shown when using
the LiPo pack. It can also be mounted below the servo tray on
top of the framework for the gear mains. When using the 10-cell
E-flite NiMH pack that weighs 12.8oz, move the Expert receiver
pack aft by about 3" for proper balance.
Expert receiver pack is used in conjunction with the Expert (EXRA050)
Standard Switch with charging cord so you recharge it right in
the plane. This eliminates the possibility of a BEC failure under
extreme heat, humidity (thicker air), and servo drain conditions.
I am not certain if it has been determined that this conditions
happens often enough to justify the setup. It is a recommendation
by Horizon Hobby for safety due to the specifications of the ESC's
8% range of flying weight due to various setup is as follows:
59oz (3.7lbs) with LiPo option and using BEC in ESC
62oz (3.9lbs) with NiMH battery pack and using BEC in ESC
64oz (4.0lbs) with NiMH battery pack and using Expert receiver
finished E-flite J3 Cub 25 balanced perfectly with either pack
installed and weighed 59oz (3.7lbs) Ready-To-Fly (RTF). The power
system measured 350 watts at 33amps for about 95w/lb which guarantees
We test flew the J3 Cub 25 with total success. It simply flew
as expected...magnificent! The E-flite 25 outrunner provided
awesome power which means my next test with floats is guaranteed
to be successful. The NiMH pack provided about 10 minute flights
and the 4200mAh LiPo pack about 20 minute flights. The flight
time will vary depending upon the amount of aerobatics performed.
first video of the J3 Cub 25 is on land with the stock wheels.
The winds were rather brisk for a 25-size plane at 10-15mph
but the Cub proved to have plenty of power.
J3 Cub 25 Video
is time to try out the optional E-flite 25-Size Fiberglass ARF
Floats (EFLA500). The E-flite quick-mount floats are designed
specifically for 25-size planes that are float-ready out of the
box, so you can go from pavement to pond in just minutes. I plan
to video the J3 Cub 25 on floats taking off from both water and
float assembly went without a problem as the instructions were
simple and well written. The J3 Cub 25 is also a float-ready design
by E-flite. After removing the stock gear mains, I cut the covering
off the rear most channel and mounted the float mains.
the brackets were screwed into the floats and flat spots filed
onto the tops of the float mains for better hold by the wheel
collar set screws. I used a Dremel tool grinder to make the entire
top of the float mains extensions flat. The floats were then mounted
and the collars secured using Pacer Z-42 Thread Locker. Note that
there is one float with extra holes in the aft end that is meant
to mount on the side were the rudder linkage is located.
float kit provides a ventral fin for adding stability in flight,
especially at slower speeds. The ventral fin mount is screwed
into place in the pre-drilled holes under the Cub fuselage. After
cutting away some covering, the fin itself is glued into the mount
with epoxy. I used 5-minute ZAP Z-poxy.
water rudder and linkage assembled fine and I did not see any
excessive resistance added to the rudder throw. My only modification
was to make two of the full brass strips into half strips for
easier mounting. I used a Dremel tool to cut off the unwanted
end. I also managed to break one of the quick links so I replaced
it with a similar size one from my own supply. There was about
1/2" excess cable that I cut off from the float end.
testing the water rudder assembly, make sure that it follows the
normal rudder direction and that it can flip up with little resistance
if it hits a rock or some obstruction in the water.
The Cub looks great with the floats attached. I can't wait to
test it out!
Cub 25 Video 2
second of three videos has the J3 Cub 25 on floats taking
off grass. We made the floats extra slippery by spraying
Pledge furniture polish on the bottom. Again, the Cub performed
flawlessly. The power level and ground steering is proof
that it will perform fantastic off water!
Cub 25 Video 3
we tested the J3 Cub 25 on water, it performed very well. The
high power level of the E-flite 25 outrunner motor and the very
rigid design of the float cage allows you to take-off and land
even in small areas. The video was taken on a single charge of
the ThunderPower 3s2p 4200mAh Lithium pack option. Even with the
flying part mostly cut out of the video, we only used 60% of the
pack as displayed on the Cellpro 4s Balancing Charger.
covered the bottom holes with masking tape on the inside and removed
it when we were finished flying. Some water does splash up on
the bottom of the fuselage but probably not enough to cause a
The E-flite J3 Cub 25 is the best .25-size scale float plane that
I have seen to date. No adjustments were made to the CG and it
was flying slightly tail-heavy...which is just how we like it
for slower landings. It was designed from the ground up to fly
well on either wheels or floats and I made no changes from the
stock setup or design. I really liked the magnetic mounted hatch
on the fuselage bottom for easy battery access and recharging.
The entire build was easily done by following the manual and the
only soldering required was to add battery connectors.
solid design of the Cub frame, wing, and accessories makes it
rugged enough to handle those less than perfect landings on either
ground or water. This model will not break just by picking it
up or puting it in your car for travel.
power level provided by the E-flite Power 25 Outrunner motor is
a perfect match for the Cub, allowing it to easily take off water
and perform aerobatics. The electric power system keeps the Cub
clean and quiet for those early morning flights on a calm lake.
J3 Cub 25 off Grass
Cub 25 off Water
Distributed Exclusively in the U.S.A. by:
Horizon Hobby, Inc
4105 Fieldstone Road
Champaign, IL 61822
Ph: (800) 338-4639
Toll Free: (800) 338-4639
Fax: (217) 352-6799
5716A Industry Lane
Frederick, MD 21704
Sales: 800-343-2934 or 301-668-7614
Glues On-line at Frank Tiano Enterprises
Z-42 Thread Locker
Pacer POLY ZAP(tm)
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.
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