RCU Review: Graupner Piper J3 Cub


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    Contributed by: Marc Vigod | Published: July 2002 | Views: 73246 | email icon Email this Article | PDFpdf icon
    Graupner
    Piper J3 Cub
    Specifications:
    • Kit Name: Piper J3 Cub

    • Price: $169.00

    • Wingspan: 72"

    • Wing Area: 690 sq. in.

    • Length: 40"

    • Flying Weight per mfg: 6.5 lbs.

    • Flying Weight as tested: 7.5 lbs (see text)

    • Wing Loading: 21.7 oz/sq. ft at 6.5 lbs. and 25 oz/sq. ft. at 7.5 lbs.

    • Motor used: Saito FA-80 Four Stroke Glow Engine

    • Prop: APC 14x6

    • Radio and gear: Hitec 7ch rx, Hitec 422 servos (5), rx battery 2400 Nimh, Hitec Eclipse Tx.

    • Channels Used:4 total - elevator, aileron, rudder, throttle

    • Manufacturer: Graupner

    • Distributor: Hobby Lobby

    Intro

    The Piper J3 Cub is one of the most classic aircraft in history. It was 1938 when Piper introduced the J-3 Cub. Powered by 40-hp Continental, Lycoming or Franklin engines, the J-3 sold for $1,3OO. Engine horsepower was soon raised to fifty and reached sixty-five by 194O. Piper also standardized a color scheme; just as Henry Fords Model T's were all black so William Piper's Cubs were all bright yellow with black trim.

    J-3 SPECIFICATIONS
    MANUFACTURER Piper Aircraft Corporation
    TYPE Trainer
    ENGINE Lycoming 65-hp air-cooled
    WINGSPAN 35' 2"
    LENGTH 22' 2"
    HEIGHT 6' 8"
    GROSS WEIGHT 1,220 lbs.
    MAXIMUM SPEED 85 m.p.h.
    RANGE 190 miles
    RANGE 9,300 ft.
    CREW Two in tandem cabin

    The J3 Cub is one of the most modeled planes in the RC hobby. For many years I've always longed to own a J3 Cub with it's classic lines and gentle flight characteristics but never owned one....until now.

    This ARF Cub comes from Graupner and when the colorful box with very nice 4 color pictures landed at my doorstep I became very excited that a Cub was finally in my future!

    Packaging the Graupner J3 Cub arrived in.


    (click images for full size)


    Hits
    Misses
    • Fast easy assembly
    • Perfect covering and finish work
    • Excellent fit of parts
    • Prehinged and pinned control surfaces
    • Extensive quality hardware package
    • Fiberglass Cowl
    • Kit was a bit heavier than manufacturer specs (see notes)
    • Manual was in german but when shipping I'm told will also be translated into English
    • Plastic tubing for fuel tank lines

    Kit Features
    Required Items
    • Fully covered wing, fuselage, tail and landing gear fairings.
    • Wheels, wheel caps & landing gear
    • Fuel tank, clunk & foam
    • Motor mount preinstalled
    • Pushrods preinstalled
    • Prepainted fiberglass cowl
    • Finished wing struts
    • Steerable tail wheel
    • Wing bolts, control horns, clevises.
    • Other assorted hardware
    • 4 channel radio with 5 standard servos
    • Engine .46 two stroke or .72 - .80 four stroke
    • CA glue, epoxy, loctite thread lock
    • Propeller
    • Spinner nut
    • Standard building tools

    Assembly of the J3

    I unpacked the box to reveal the contents which were packed well

    (click images for full size)

    Here are the parts out of the "wrapper"

    There really isn't a large amount of work left to finish this kit as you can clearly see from the pictures of how it comes out of the box. All that is needed is the basic final assembly and your ready to take this Cub to the air. The manual included was in German but with many pictures. I followed the pictures and had little trouble. Hobby Lobby informed me that when this ARF ships it will include a translated instruction manual.

    WING

    Installing the aileron servos is as simple as removing the 4 hatch screws from the preinstalled panel and screwing the servo into the blocks. Run the servo wires through the wing using the preinstalled "snake" (string) and it's done.

    Precut panel for aileron servo (click images for full size)

    With the aileron servos installed the wing is joined together. Using the supplied plywood joiner, epoxy it into one half of the wing and then into the other half. Add some epoxy to the center root ribs as well when joining. Wipe off any excess epoxy with some alcohol. The dihedral is build into the joiner itself. The fit of the joiner into the wings was absolutely perfect. To complete the wing simply add decals, control horns and pushrods to the aileron servos.

    FUSELAGE

    Inside of fuselage exactly as it comes out of the box.

    Pushrods and servos trays preinstalled.

    You can see in the picture above the pushrods, servo tray and switch tray already preinstalled. All that's left to do in here is install the 3 servos, screw in the radio switch and cut the pushrods to final length.


    I installed 3 standard HS-422 Hitec servos in the fuselage. They fit perfect in the preinstalled tray. The battery was installed behind the servos to balance the plane with the larger Saito .80 in the nose. Later I would learn that I needed to move the battery behind the tank to balance.

    Servos, switch, battery and rx all in place!


    Dashboard is even installed. Note fuel tank opening on bottom.

    The fuel tank is assembled and pushed through the opening as seen in the above photo. It slides right into the cutouts made into the fuselage formers and was a perfect fit at that. One thing I didn't like on the fuel tank was the plastic fittings. I prefer brass and found the plastic impossible to bend and hold shape. I decided to substitute the filler line and vent line with brass ones but left the main supply line as it was.


    Firewall already has bolts for mount installed. Motor pushrod preinstalled (bottom right)
    Installing the provided 2 part adjustable motor mount is as easy as removing the 4 screws, adding loctite and fastening the screws down onto the mounts. I dry fit the motor to get the spacing correct on the mounts.

    Landing gear is pre assembled. Screw it on with the provided 6 straps and self tapping screws. The fairings are drilled and secured to the landing gear with plastic ties.

    Once the landing gear is secured to the fuse (see picture and caption above) the wheels are put on using the provided wheel collars. The plastic hubs are then secured to the wheels using the supplied self tapping screws.

    To install the horizontal stabilizer you simply cut away the covering on the stab where it will contact the precut slots in the fuse. Trial fit the stab to mark the lines which you need to cut. Once the covering has been removed simply glue the stab in place (check for alignment). Next the vertical stabilizer glues into the precut slot on the top of the fuse. The fit of both of these parts was dead on.

    Close up of the tail. You can see the tail wheel and pinned hinges on all surfaces (control surfaces are pre hinged)
    Finished struts are attached to 'eyelets' which screw into the wing. Once adjusted for length the setscrew is tightened on the strut.

    I didn't install the supplied plastic dummy engine pieces to both sides of the cowl as I had not painted them yet as of the time of this writing but they are included and can be added for an even more realistic scale J3 look.

    The manufacturers weight for this aircraft is listed at around 6.5 pounds but mine came in closer to 7.5 pounds. I wasn't too concerned as the difference only came out to about 22 oz/sq.ft. versus 25 oz/sq.ft. of wing loading. The difference is partially due to the standard servos. A higher torque lighter servo could be installed and save around 3 ounces. I also used the larger Saito 80 motor which was a few ounces extra. Lastly I used the 2700 Nimh pack versus a standard nicad pack so another few ounces there. If you back all those "extra" ounces out you probably save about half a pound which would bring the Cub to around 7 pounds dry.

    Completed J3 Ready For Flight
    Saito 80 installed and cowl cut to accommodate head and muffler.

    Photo of the underside
    Beautiful scale looking shot of the J3 at the field assembled and ready for takeoff!
    Front view of the J3 getting ready for the maiden voyage.
    The rear view of the J3.

    Flight Testing and Evaluation
    As is customary I waited for a perfect day to bring the Cub on her maiden flight. That perfect day came or so I had thought and packed up the Cub and off to the field I went. Once I arrived at the field it was a bit breezier than I like to fly in let alone a first flight. Also from what I have been told a Cub is not the best aircraft to fly in heavy breeze conditions. So normally I would abort but I was anxious to fly the Cub and I figured "how bad could it be?"

    So the decision was made to forge ahead. I did a last minute check of all control surfaces, range check and double checked the CG. We fired up the Saito 80 four stroke and taxied out away from the pits area. I applied full power and was mindful of ground looping or some of the other things to watch for with tail draggers and Cubs specifically. The J3 lifted off nicely and banked a little bit to the right and continued to climb out. After a little bit of altitude was attained on the climb the J3 started banking left with the wind pushing it around. I was trying to trim it out but in the windy conditions it was difficult. I had noticed the controls were set too sensitive by me so I switched to low rates but it was still very touchy. I usually set up more throw than necessary and dial it down with the computer radio. This time I couldn't dial down enough in the air to tone it down to fly it comfortably. This was my fault for setting the throws to the extreme.

    I handed the sticks to Chris, one of the flyers at my field, and had him test it out as he had flown a Cub before plus I wanted to get a few photos of it in the air. He flew it around for the photos and finished with a nice landing but also felt it was too windy and the throws were too aggressive. So I waited for the wind to break that day but no cooperation from mother nature came so we packed up and went home.

    J3 Cub on it's first flight
    Another shot of the Cub as it goes by on it's maiden flight

    Again I waited for the weather to break and the perfect day did come. Virtually zero wind and comfortable temperatures. I packed up and headed to the field. I quickly fired up the Saito again and rolled out quickly. With the controls now mechanically & electronically reduced I could feel it was going to be a bit tamer this time around. The Cub took off and climbed out with authority at 3/4 throttle. I trimmed her out and did a few slow scale flybys with the 4 stroke adding to the scale look and sound. A very beautiful sight.

    It was time to test some basic aerobatics and stall characteristics. Slowing down the Cub and holding the nose up to stall the aircraft showed no bad tendencies. A wing tip drops and you add some power or pick up speed to recover. Loops required a bit of aileron to keep the wings level towards the top but were easy to perform. Rolls are predictable and require some down elevator while inverted through the maneuver. Inverted flight only required a bit of down on the elevator. Stall turns were simple and come off as expected.

    I did make it a point, as my fellow flyers recommended, to perform turns by coordinating rudder and aileron as it is done in full scale airplanes. This helped quite a bit to push the Cub through a turn I found.

    Landings are very simple as the Cub slows down so nicely before hitting a stall speed. I just lined it up down the runway and let her settle in while providing only minor corrections to keep the landing approach straight. She landed beautifully and I brought her back in to fuel her up for a few more flights.

    On my next flight I stayed up a little too long and the motor ran out of fuel so I was about to test a dead stick landing on my 3rd flight. Ironically a fellow at my field was also flying his Cub and called out dead stick too exactly when mine was also coming down. So we had two Cubs both coming in sans motor running. This plane with it's slow speed and ability to float along was a breeze to land without the motor running. Same procedure as the previous flight with the only difference being I had one shot to get it right. The Cub made it easy to get it right and a graceful landing was made.

    One thing I will change but have not yet as of the time I'm writing this review is the battery location. I installed it behind the servos and feel the plane may be a slight bit tail heavy so I plan to move it right behind or under the fuel tank. It was a 2700Nimh battery pack so a bit of weight was added to the aft CG area by placing it there. Why such a huge pack? I had it on hand and knew the Cub could handle the few extra ounces.

    I took another flight with the Cub and it was lots of fun to fly. I'm more accustomed to flying Extra's and Cap's so the drastic change of pace to the J3 was very interesting for me. I'm looking forward to many more flights with the J3 in the future.

    FINAL WORDS

    The Graupner Piper J3 Cub ARF was a very fast and easy aircraft to assemble. I was very pleased with the quality of construction, perfect covering, quality hardware as well as how extensive it was.

    Flying the J3 was truly lots of fun. Although the first flight had me wondering between the high winds and extreme throws I had setup the subsequent flights proved that the J3 was a stable and predictable aircraft. For anyone in the market considering a Piper J3 Cub the Graupner ARF is a fine choice especially considering the $169 price tag! This is alot of plane for so little money with all of the hard stuff already done for you.

    REVIEW RATINGS

    Kit Quality

    (1=Not so good, 5 = Excellent)

    Packaging Quality:

    1 2 3 4 5

    Construction Quality: 1 2 3 4 5
    Hardware Quality: 1 2 3 4 5
    Quality of Manual: 1 2 3 4 5
    Ease of Assembly: 1 2 3 4 5
    Completeness of Kit: 1 2 3 4 5
    Covering Quality 1 2 3 4 5
    Flight Characteristics
    Take-Off: 1 2 3 4 5
    Landing: 1 2 3 4 5
    Basic Aerobatics (loops, rolls, etc.): 1 2 3 4 5
    Advanced Aerobatics (snap roll, spins, etc.): 1 2 3 4 5
    Stall Characteristics: 1 2 3 4 5

    Manufacturer & Distributor Information

    Hobby Lobby
    5614 Franklin Pike Circle
    Brentwood, TN 37027 USA
    Phone: 615-373-1444 Fax: 615-377-6948
    Website: www.hobby-lobby.com

    Graupner
    Website: www.graupner.com

    Hitec RCD USA, Inc.
    12115 Paine St.
    Poway CA, 92064
    Phone: 858-748-6948 Fax: 858-748-1767
    Website: www.hitecrcd.com

    Horizon Hobby Inc. (Saito Distributor)
    4105 Fieldstone Rd.
    Champaign, IL 61822
    Phone: (217) 352-1913 Fax: (217) 352-6799
    Website: www.horizonhobby.com



    Comments on RCU Review: Graupner Piper J3 Cub

    Posted by: KrashMaster on 08/04/2008
    This model is completely discontinued, There seems to be none of the mentioned websites above that have or intend to restock these wonderfull birds? Even Graupner has dumped them.
    Posted by: marcv on 08/04/2008
    You are likely correct. It is probably discontinued. This was reviewed quite some time ago. the review remains in our magazine archive though in case somebody has one laying around and is interested in it.
    Page: 1
    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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