This item is discontinued.

GREAT PLANES PIPER J-3 CUB ARF
PRODUCT TEST REPORT
by Dick Pettit

Type: ARF Standoff Scale
Manufacturer: Great Planes Model Mfg. Co. P.O. Box 9021 Champaign, IL 61826
Distributor: Great Planes Model Dist. Co.
Suggested Retail Price: $299.95
Wing Span: Advertised 81"
    Measured 81 5/8
Wing Area: Advertised 984 sq. in.
    Measured 947.5 sq. in.
Airfoil: Flat bottom
Fuselage Length: Advertised 49"
    Measured Overall 53.5"
Rec. Controls: 4 (Ail, El, Rud, Throt)
Rec. Engine: .40-46 2C or .48-70 4C
Rec. Weight: 8.5 lbs.
Basic Materials: Balsa and plywood
Instructions: 24 pg. illustrated manual
Hardware Included: Adjustable engine mount, fuel tank, formed wire main, and tail gear, main and tail wheels, wheel collars, self adhesive markings, formed plastic windshield and side windows, all control linkages, and all necessary nuts, bolts, and screws.
Items Needed To Complete: Spinner, prop, engine, fuel tubing, 4-ch radio system w/5 std servos, and some assembly adhesives
Plans: None required

COMPLETED MODEL
Finished Weight: 8.7 lbs. (139 oz.)
Wing Loading: 21.13 oz. /sq. ft.
Engine Used: O.S. FS-70 Surpass (20.3 oz.)
Propshaft to Ground: 10" (held level)
Fuel Tank Used: 12 oz., as supplied
Radio Used: Hitec Flash 5 w/5 std servos
Covering/Finishing Used: Comes precovered
Special Items: Du-Bro's chrome prop hub

CHEERS - Very complete kit, with top quality hardware; very easy to assemble; excellent and very stable flight characteristics; a joy to fly!

JEERS - Tail wheel mounting; covering work; some construction steps listed in the manual have already been completed; some areas were poorly sanded.

"The hits just keep on coming" That's what I have to say about the quality and quantity of Almost Ready to Fly (ARF) planes available today. And it only makes sense that manufacturers and distributors would choose the more popular full scale planes as the basis for the new ARF kits.

The Great Planes ARF Piper J-3 Cub is an 81" span version that can be powered by a reasonably small engine, and requires no more than a standard 4-ch radio (with five servos) for guidance. There are already some giant scale J-3 ARF kits available, but the Great Planes version is a little different. Not only does this kit contain top quality brand name hardware and accessories, but it's also completely covered with Coverite 21st Century fabric, not some cheap plastic film as found on some versions. Another welcome feature is the fact that all of the details, including the N numbers, are provided, but not pre-installed. This allows the builder to create a Cub that doesn't look exactly like all the others at the flying field, right down to the same N-numbers.

The Great Planes ARF J-3 arrived in a fairly large box, inside which I found a pair of wing panels, the tail surfaces, and a fuselage. All of these pieces were neatly enclosed in separate plastic bags protected by cardboard spacers. Also included are a set of scale like Cub wheels, a bag of good quality hardware, a Great Planes fuel tank, a set of assembled and covered wing struts, and several sheets of self-adhesive stickers.

The instructions book is fully illustrated, and provides not only building instruction, but includes information on joining the AMA, and helpful flight information for the J-3 Cub. But I soon noticed several minor discrepancies between the kit and the instructions. First, on the front cover, right below the words "Piper J-3 Cub" is a line that says "Quarter Scale". Looking at the indicated wingspan of 81", somebody must have mistaken the "IMAA Legal" designation to mean 1/4 scale. This particular Cub scales out at about 1:5.31, a little smaller than even 1/5th scale. Next, looking at the photos on the kit box, don't be disillusioned by the photo of the less than appealing wheels and fuel tank shown. The supplied wheels are quite nice, and about the right size, and the supplied fuel tank is a good Great Planes unit, not the flimsy round plastic medicine bottle found in many ARF's. Finally, on the last page of the instructions, under the "Flying" section, Great Planes stated that the "...J-3 Cub is a great looking scale airplane... true to its full scale counterpart, is fully aerobatic:. I hope they consider left turns, right turns, and maybe a gentle stall turn to be "fully aerobatic", because that's about all a full size standard-wing Cub could do! As with nearly all scale subjects, models can be made to perform aerobatic maneuvers that their full scale counterparts could never accomplish.

These are just minor nitpicks, however, and nothing that should stop the prospective owner from buying and building the kit.

Upon close inspection, it appears that the framework of the GP Cub was built by someone who missed their classes on sanding. There were several rough edges showing under the fabric covering that probably could have been easily removed had the factory builder taken the time to use a little sandpaper before applying the covering.

Actually, the covering job itself was somewhat less than optimum. 21st Century fabric should be applied as described on its instruction sheet, not like most plastic films. Maybe the covering technician didn't get a copy of the instruction sheet, because I had to iron and shrink the covering three or four times before all the bubbles and sags disappeared. Otherwise, everything seemed to be ready to begin, so I'm finally ready to start assembling the pieces.

I got off to a false start with the Cub because the first stop to perform is to fuel proof the firewall area. The firewall on my kit was already coated with some kind of epoxy, so off we go to step two, joining the wing halves. The plywood dihedral brace parts were Zap'd together and test fit into the wing holes. The book says the wing can be built flat on the board, but as standard procedure for Cubs, I added a little dihedral so that the wing doesn't appear to droop. A truly flat wing will appear to have anhedral, or downward sloping wing panels. There's plenty of extra space to add a little dihedral, and surprisingly, the root ribs were already beveled to the desired angle! A nice application of Pacer 30-min epoxy holds everything together.

Next is mounting the engine to the adjustable engine mount. Using the supplied drilling template, holes were bored for blind nuts, and the O.S. FS-70 Surpass was bolted into place. Holes in the firewall for the throttle linkage and fuel lines were also drilled at this time. Using some cardboard templates, the plastic cowl was cut for the engine and muffler. The cowl, even though reinforced with a thin layer of fiberglass cloth, started to develop a few cracks. The Great Planes 12 oz. fuel tank was assembled and installed under the dashboard. It seems to be mounted a little on the low side, but there's room to raise it half an inch or so.

When it came time to mount the wing to the fuselage, one stop was already completed, installing the blind nuts for the wing bolts. They were not glued in place, however, so I added a drop or two of medium Zap to keep them in place. Then the wing was squared to the fuselage, and the bolt holes in the wing were made. A plywood plate was then drilled and installed to support the bolts during tightening.

Next the stab was installed, square to both the wing and fuselage. No major sanding was necessary to get it right. Since there were a lot of wood surfaces touching, I used a bead of thin Zap to secure the stab in place. The fin was secured with medium Zap.

The kit includes one of those flimsy plastic tab type tail wheel brackets that places a lot of strain on the rudder. I installed a plywood plate to the bottom rear of the fuselage, and installed a Goldberg Klett .60 size tailwheel mount.

The supplied main landing gear is a set of plated wires, formed into shape and inserted into slots on the bottom of the fuselage. The torque wire gear may be fine, but I may make arrangements for another style of main gear legs. The covering was already cut out for the landing gear wires, so they were just slipped into place and secured with two plastic straps. The side fairings were attached using the supplied wood brackets, made with a hinge at the flex point using what looks like a CA type hinge. Neat idea! The main wheels were installed using the supplied wheel collars, after grinding flat spots on the wires for the collar screws.

The elevator joiner wire was installed, and the completed elevator was hinged into place using the supplied hinges. I added another hinge to each side, though, because I didn't feel that two per side were enough. The rudder and ailerons were also installed using the supplied hinges and thin Zap. Control horns and solid wire linkages were cut to size and installed, and connected to standard servos. The cut already has a nice servo mount, but the holes may need to be enlarged for some servos. The solid wire pushrods ride inside plastic tubes that are installed in the fuselage. The solid throttle linkage was also installed and adjusted for proper operation. There were numerous construction steps in the instructions that were already done at the factory, but they made up for it by not cutting out the covering over the side windows, as shown in the manual. It didn't take a lot of effort to cut the covering away, but it should have been mentioned in the instructions.

The formed plastic windshield and side windows fit perfectly, and the Cub was just about complete. The side stipe and lightning bolt were installed, as shown in the manual. The wing struts, mandatory for flight, also uses CA hinge flex points at both ends. The struts are secured to the fuselage and wing after verifying that the wing panels have no twist in them. This can be checked using an incidence meter, or a level with the assembled plane turned upside down. The struts are secured with 1/2" wood screws.

With the receiver installed in front of the servos, and the battery placed under the fuel tank, the Cub balanced perfectly at the indicated point. Interestingly, the CG is a full 33% behind the leading edge. I usually like to start closer to 25%, but I don't think the recommended starting point will be far off.

It's done! That didn't take long, did it? Even after ironing the covering down once more to remove the sags and wrinkles that developed during a week of hanging in the workshop, it took less than the 15-20 hours stated in the manual. Everything fit, there were no missing parts, and the instructions made everything perfectly clear. I don't even think the stops already completed on my kit made any difference to the speed in which the Cub was built.

During engine testing, the O.S. FS-70 Surpass started easily, and after a little tweaking on the carburetor adjustments, it settled into a nice, low idle and responded instantly when throttle was applied. Taxi testing proved there would be no lack of power to fly the Great Planes ARF Cub.

I took an afternoon off from work to test fly the Cub, and headed for the flying field. I unloaded the Cub from my trailer, and within five minutes had it assembled and ready to photograph. Once the pictures were taken, the Cub was given a thorough pre-flight inspection, the fuel tank filled, and the radio range checked, just like every model I test fly. The engine started on the second flip, and the needle was set for a slightly rich setting. After several false starts which resulted in further adjustments to the low speed needle, I was ready to test fly the Great Planes Cub.

Low speed taxi tests proved ground control to be excellent. High speed runs lifted the tail in just a few feet, and there was good control authority from the rudder, so I decided it was ready to fly.

With its nose pointed into the wind, the throttle was slowly advanced. A bit of right rudder corrected a slight turn to the left, and the Cub was quickly airborne. The slight crosswind was pushing the tail to the left, but I made no effort to correct it. A gentle turn to the left required a little left rudder to keep the tail from dragging, but no trim changes were necessary for straight and level flight.

After a few part-throttle passes, I started to take the Cub to a safer altitude, realizing only then that the engine was still running at half power. Once at a comfortable altitude, I cut the power, added all the elevator it had, and watched as the Cub just hung there, almost motionless for a moment, before finally dripping its nose, and resuming forward flight. I tried to force it into a spin, but the Cub only bobbed around, probably due to being slightly nose heavy.

Back at the lower altitude, I made several low, slow passes for the photographer, followed by an attempt at a slow roll. The Cub actually did a pretty decent axial roll, which is not Cub like at all. A barrel roll proved to be the best looking of all the rolls attempted, and certainly one that many full scale Cubs have performed. The Great Planes Cub did a nice stall turn and a cub like loop, and my favorite, the sliding turn, looked really nice. I tried inverted flight, and the model handled it, but a Cub just doesn't look good when upside down. Low, slow passes down the runway, however, are a thing of beauty.

The first landing was uneventful. Power was reduced, the nose was pointed at the end of the runway, and the Great Planes Cub settled down to a smooth landing. That's the way all test flight sessions should be. I took the Cub to the pit area for a post flight inspection, and found that the dummy engine I had glued to the left side of the cowl had blown off somewhere over the surrounding farmland. I made no attempt to find the missing piece, mainly because the farmer who owns the land was spraying a dark brown liquid on the fields, and it wasn't chocolate! I'll just get another dummy engine, thank you!

I flew the Great Planes Cub several more times that day, performing several touch and goes and a few non-scale maneuvers. I would highly recommend that builders of this Cub follow Great Planes recommendation of always flying with the wing struts in place, since they are functional, and they do help keep the wing from folding. Besides, who ever saw a real Cub without wing struts?

At the end of the day, I was happy with the results, and felt confident that the Great Planes Cub would be a fine addition in anyone's hangar. Subsequent flights later on have done nothing to change that initial impression.

So, there you have it. Another very nice ARF model that just about anyone would be proud to own. The Great Planes ARF Cub, with its nice fabric covering, assembles easily, seems to be strong and light, is capable of being flown with many different engines, and requires only one extra servo for use with standard, entry-level 4 ch radios. It looks great on the ground and in the air, and flied like a dream. My Cub, with its O.S. FS-70 Surpass, may be slightly overpowered, but it really sounds nice at half throttle. Once the covering was re-tightened, and the engine tuned correctly, the Great Planes ARF Cub was a joy to fly, and I'm sure there will be quite a few of them at the flying fields.