|Wing Area:||550 sq. in.|
|Wing Loading:||17.27 oz/sq. ft.|
|Servos:||four JR Sport MN-48|
|Transmitter:||Hitec Optic 6|
|Battery:||EE-flite 10-cell 12V 1800mAh Ni-MH (EFLB4010) or Thunder Power 3-cell 4200mAh Li-Po (THP42003S2PPL)|
|Motor:||E-flite Power 25 Outrunner (EFLM4025A)|
|ESC:||E-Flite: 40 amp brushless|
|Available From:||Horizon Hobby|
The Piper Cub, one of the most popular and influential light aircraft ever manufactured, is still synonymous with general aviation in the United States, even more than 80 years after its introduction. Initially powered by a 40-horsepower engine and selling for $1,300, the uniform color for the Cub was bright yellow, trimmed in black. Lilliputian by today's standards, the two-seat J-3 Cub was only 22 feet 2 inches long, stood 80 inches high, and had a wingspan of 35 feet 2 inches. Later powered by the Lycoming 65-horsepower engine, the J-3 Cub attained a maximum speed of 85 miles per hour with a ceiling of 9,300 feet. Even more remarkable, the fuel tank held only 12 gallons, sufficient to fly about 190 miles. Compare this to your modern automobile! Although Piper Aircraft ceased production of the venerable Cub after WWII, there are many still in use today, and it has become a staple aircraft in many an r/c enthusiast's fleet.
Unlike nearly every modeler I've ever met, I had never owned a Cub, so upon hearing that Horizon Hobby was introducing a 25-size electric model, I knew I wanted one!
As always, E-Flite's instructions are excellent, and I won't rewrite them here. Instead, lets look at an overview of the build, and a few tips, highlights, and one "oops", which has been fixed in later production kits.
The entire assembly was simple and straight forward. For the wing -- install the wing joiner, CA hinges, servo blocks and mount servos to the doors. Extra-long JRPA212 servo arms were used to allow clearance and control throw for the aileron servos.
TIP: It is always best to have an extra set of hands when gluing wing halves together, especially a wing of this size. This helps allow for proper alignment and makes removing the excess epoxy much easier.
The 30" fuselage was extremely light and very strong. The pushrod tubing, motor mounting holes, and a cooling system were factory mounted.
I used the recommended Expert (EXRB100) 4-cell, 4.8v, 720mAh AAA NiMH receiver pack to eliminate the need for the BEC feature on the E-flite 40amp ESC. The fuselage windshield comes pre-trimmed and painted. I used canopy glue and painter's tape on the canopy and windows.
I did have to cut back the covering before mounting the tail. Upon careful checking, I found the alignment of the tail was perfect!
I installed the Expert receiver battery just behind the windshield with velcro. The fuselage even included a tube for routing the receiver antenna out the bottom!
I was surprised to find that the pre-mounted blind nuts in MY J-3 Cub 25 firewall were a different size than the included hex screws that came with the motor. Although the correct matching screws for the pre-mounted blind nuts were included with the J3 Cub kit, they were too large for the holes on the motor's firewall X-mount, requiring they be drilled out. Just be sure to drill the holes out before you attach the X mount to the motor, such as on a drill press.
NOTE: Horizon Hobby has corrected this issue between the Power 25 motor screws and the J3 Cub 25 pre-mounted blind nuts, so your J-3 Cub 25 ARF will likely not need this modification be done.
All that was left to do was to install the wing by plugging the aileron y-harness into the receiver, bolting the wing down with the supplied bolts into the pre-installed blind nuts, connect the battery to the ESC, secured it inside the battery compartment with velcro and install the battery door.
The AUW range with the two battery configurations: 60oz with the 3S2P 4200 Lipo and receiver pack, and 63oz with 1800 NiMh pack and receiver battery. As you will read, both packs worked very well!
Along with the Cub 25 ARF, Horizon Hobby sent their optional float kit (part#EFLA500), which also fits their Ultra Stick 25. Made of painted fiberglass and sporting a functional water rudder, the floats can be mounted at the field in about 5 minutes! Designed for easy assembly, I had the floats completed and ready to attach in just over an hour.
All that needed to be done was:
NOTE: A removable ventral fin mounts under the tail to help stabilize the Cub in flight.
Now for the biggest surprise. On the day of the "Cub on floats" maiden flight, I arrived at my club field and realized I hadn't recharged the TP 3S2P 4200 Lipo battery, but I HAD charged the E-Flite 1800 mAh NiMh. Would it provide enough power to fly the Cub off the water? Only one way to find out, so I put the 1800 NiMh on the charger to "warm it up", and in five minutes it was ready. I checked the CG(perfect) and headed to the nearby boat ramp. Keep in mind as you watch the video that it IS the maiden flight on the floats!
As I taxied out to take off, I eased the throttle forward with full up-elevator until the Cub 25 came up "on step", then backed off the elevator and eased into it again. As the Cub gently lifted off the water and into a nice, gradual climb, I was simply amazed at the power the 1800 NiMh battery produced. The Cub 25 seemed unaffected by the extra weight of the floats and slightly heavier battery, and what a beautiful flier on floats she is (you can hear my friend and fellow photographer Johnathan's reaction on the video).
As expected, the J3 Cub 25 flew wonderfully! The maiden was done on an unexpectedly windy day, 8-10mph, with gusts up to 14mph. Needless to say, I was a bit nervous, so I chose the Thunder Power 3S2P lipo pack for extra power, less weight and longer flight time. The J-3 Cub was more than up to the task and handled the wind without any problem, and the E-flite 25 outrunner is a perfect match to this plane, providing terrific power with excellent thrust, swinging the 12 X 6 prop easily. Just like it's full-scale counterpart, the E-Flite J-3 Cub is no speed demon, but I was surprised at the speeds I could attain with full power.
I first practiced taxiing, and this proved extremely easy, thanks to the steerable tail-wheel. The wind was fairly steady at an angle to the runway, but the 60-63oz flying weight proved to be a big advantage in ground handling and gave the Cub a very stable presence.
As a flying friend described, all Cubs "fly on the wing" and after a few passes over the field I immediately understood what he meant, as the Cub lifted off and climbed steadily under full power. Even with the stiff winds, the Cub 25 was rock-solid in the air and flew very scale-like, especially at half-throttle.
As I lined up on the center of the runway, the wind picked up a bit while I slowly throttled to full power. The E-Flite Cub 25 gently lifted off in less than 15 feet and climbed out at a nice shallow angle. Landings were easy and predictable. Be sure to read the sidebar on flying off floats!
Big, smooth, scale loops are easily accomplished by simply applying full power, entering a shallow dive, and applying about a half stick of up elevator. They are a thing of beauty with the E-Flite 25 Cub.
I was very surprised at how axial the rolls were! Just start with some throttle, a little nose-up attitude and full left aileron for a nice, crisp roll. Even with the floats attached, the Cub still rolls nicely.
Thanks to its large rudder, the Cub will perform nice, smooth hammerheads!
The Cub will fly inverted fairly well but a good amount of down elevator is needed to keep the nose up.
I took her up to a safe altitude and eased back on the throttle to induce a stall, which was very mushy and predictable. The Cub 25 recovers very quickly when throttle is applied.
I would have to say the Cub is not a beginner's plane, but for a pilot with some 3-channel rudder/elevator experience, the E-Flite 25 Cub would make an excellent aileron trainer.
The E-Flite Cub 25 was an absolute blast to build and fly, and to my surprise, whether you choose the TP 3S2p 4200 Lipoly or 1800 NiMh battery, whether flying off grass, pavement or water, the Cub will reward you with it's wonderful flight characteristics!
In conclusion, I must to say that E-Flite have hit a grand slam with the Cub 25 ARF!Last edited by AMCross; Dec 20, 2006 at 03:56 PM..
|Jan 15, 2007, 02:27 PM|
Honestly, I could hardly tell any difference, the Cub tracks so well with the floats or without. Maybe a little difference when making a turn, but never unstable.
|Jan 16, 2007, 05:28 PM|
Thanks James I sure thought you did! Maybe it was Kirby
Trikster, thanks. This Cub really does fly like a much larger aircraft.
|Jan 16, 2007, 09:48 PM|
Joined Sep 2006
Great review and I loved the videos! I am assembling mine right now and it also has the mounting bolt problem, but everything else is on track. Did you notice any bad habbits during takeoff? Some have suggested that the cub is tricky to take off and while I am a marginaly competent pilot, good rudder control abilities seem to elude me. A bit nervous about the pending maiden
|Jan 17, 2007, 01:05 AM|
From the looks of things in the video, you may be able to compensate with the lack of rudder skills by giving it more throttle, take off runs seem short as it is.
|Jan 17, 2007, 06:02 AM|
You have to stay on top of the rudder. My field is grass consequently I have longer take off rolls. I find that 3/4 throttle and staying on top of the rudder with up elevator until you build up speed, then neutral elevator until the tail lifts then slight up elevator is the trick (my cub ground loops to the right if I go immediately to full throttle.) Once in the air, it's a beauty.
|Jan 17, 2007, 07:56 AM|
That is exactly right! I didn't mention this, but we did three maidens that day, the Cub 25, the E-Flite Super Airliner and Keith Sparks' 757. It was fairly windy at a shallow angle to the runway, which actually helped keep the Cub's tail straight on takeoff.
And as I mentioned before, it handles wind really well!
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