GREAT PLANES T-CRAFT
by Dennis Adamisin
Aircraft Type Sport Scale Aerobatic
Mfg. By Great Planes,P.O. Box 9021, Champaign, IL 61826-9021. www.greatplanes.com
Mfg. Sug. Retail Price $79.99
Available From Retail Outlets
Wingspan 56 Inches
Wing Chord 9.25 Inches
Total Wing Area 498 Sq. In.
Fuselage Length 40.75 Inches
Stabilizer Span 17.5 Inches
Total Stab Area 87.5 Sq. In.
Mfg. Rec. Engine Range .20-.32 2-Stroke, .26-30 4-Stroke
Rec. Fuel Tank Size 6 Oz.
Rec. No. of Channels 4 w/5 Servos (3 mini, 2 micro)
Rec. Control Functions Rud., Elev., Throt., Ail.
Basic Materials Used In Construction
Fuselage Balsa, Ply & Lite Ply
Wing Balsa, Ply & Lite Ply
Tail Surfaces Balsa & Music Wire
Building Instructions on Plan Sheets No
Instruction Manual Yes (48 pages)
Construction Photos Yes
Radio Used Futaba Skysport 6
Engine Make & Disp. O.S. Max FS-26 Surpass
Tank Size Used 6 Oz. Du-Bro
Weight, Ready to Fly 68 Oz. (4 Lbs., 4 Oz.)
Wing Loading 19.7 Oz./Sq. Ft.
WE LIKED THE: Great kit engineering, easy to build, great plans and instruction book.
WE DIDN'T LIKE THE: Wire landing gear - soft, landing gear fairings fall off.
While Giant Scale aerobats are all the rage, sometimes it's nice to have a smaller bird that still looks great and will fit in the car all assembled. And yes, there are aerobatic aircraft that are not Extra 300's! Enter the Great Planes T-Craft, a Sport Scale version of a venerable aerobatic performer designed around the smallest 4-strokes available. In full-scale the aircraft is a distant cousin of a Cub, but the thousands who have witnessed Duane Cole's dazzling airshow routine will attest, a clipped wing T-Craft with some extra "attitude" under the hood is an impressive performer.
The Great Planes T-Craft comes in a brightly decorated 4.5" x 7.5" x 38" box covered with pictures and stats describing the model. Everything was neatly packed and packaged with paper wrapping, offering some special protection for the large molded windshield. All the die-cut parts are clearly marked with part numbers stamped on. The instruction book also includes diagrams of all the die-cut sheets offered as an aid to identifying parts. Two 36" x 46" rolled plan sheets are supplemented by an outstanding 48-page instruction manual. One of my favorite features of the manual was the centerfold. It has the plans reduced to 11" x 17" so you can follow along while you check the next building sequence. Die-cutting was the usual outstanding Great Planes effort with parts falling out of the sheets cleanly. I used Great Planes thin and medium CA for most construction along with some Great Planes aliphatic wood glue and epoxy.
I started construction with the tail surfaces. Curved segments are die-cut and the rest is framed and ribbed with various sizes of 3/16" balsa strips. These are assembled over the plan that I protected with Great Planes Plan Protector - an excellent barrier to prevent gluing the assembly to the plan! After rounding off all the edges, the elevator halves are joined using a pre-bent piece of 3/32" music wire. Great Planes supplies a large patch of CA hinge material from which the hinges were cut. I used the Great Planes hinge slot cutter to make short work of what used to be one of my least favorite tasks.
The wing is a very robust D-tube structure and the semi-symmetrical wing ribs are equipped with "feet" so the wing can be built flat on a building board. After assembly, the feet are broken off. The T-Craft uses two plywood dihedral braces between the spars which are supplemented by two 1/16" plywood braces overlapping the spars and encapsulating the other plywood braces - this wing will not break in the center joint! The center leading edge has a large cutout corresponding to the top of the windshield that is well braced with 1/8" square basswood spars top and bottom and plywood facing. Great Planes supplies a couple of really nifty plywood dihedral stands to hold the wing at the proper angle. The wing halves are joined prior to the leading edge sheeting being installed. It was easy to build a straight, strong wing.
The T-Craft has an extremely neat aileron servo mount designed for the dual aileron servos; the hollowed out ribs make installing servo wiring a cinch. The large barndoor style ailerons are built over a center core by capping the leading edge on the die-cut aileron outline core and then installing ribs top and bottom that get tapering out at the trailing edge.
Awhile back I had built a Great Planes Electri-Cub, and saw some of the same attention to weight saving detail in the construction of the T-Craft fuselage. The sides are built-up of several die-cut pieces and strip stock, with some doublers and triplers used to good effect. Lots of lightening holes are used to keep the bulk down, yet the structure is extremely strong. The upper rear fuselage utilizes a crutch to simplify and align the fuselage; all the other bulkheads are notched in. The engine is mounted rotated about 35 degrees downward from a true side mount, allowing the engine muffler to tuck inside the cowling and vent through the bottom centerline of the firewall. Great Planes has done a nice job engineering the 2 degree side thrust into the firewall and the plans show you how to locate the engine mount so the engine comes out centered. The front of the ABS cowling is also tipped at 2 degrees so the prop looks parallel with the front of the cowling. The upper rear fuselage is formed using three 1/8" dowels. I added some gussets in the dowel joints to the bulkheads.
The cowling and wheel pants are vac-formed in ABS. The instructions show how to cut narrow overlapping strips from scrap ABS then glue them in place on one shell, then join the opposite shell over it. I did all this using liquid plastic model cement. The seams are further reinforced on the inside surfaces using fiberglass cloth applied with PVC pipe cement. After filling of the seams using Squadron Putty, and some careful sanding, I would put the cowl and wheel pants up with the best I've ever seen in plastic or fiberglass. They have also proven to be quite durable.
No particular aircraft is duplicated, but I wanted a color scheme representative of an aerobatic mount. I settled on Top Flite MonoKote in overall White with Teal and Orange, and used Black pin stripes and checkerboard. The ABS cowling and wheel pants were first primed then painted (teal) with Top Flite LusterKote. The color match with the MonoKote is excellent. Great Planes supplies several decals, including an instrument panel; however, no floor is provided for a pilot. I cut one out of lite ply I had on hand and installed a 2" (1/6) scale Williams Bros. pilot. After covering, I installed the windshield using Goop adhesive. I am quite happy with the way it turned out and it has earned some appreciation from the crew at the field.
The review model was powered by an O.S. FS26 Surpass 4-stroke mounted on the Great Planes universal engine mount supplied with the kit. This is only my third 4-stroke engine and frankly I was nervous about it having enough power to fly the T-Craft through aerobatics; I soon learned that my fears were unwarranted. With the engine rotated around, it was a cinch to point the tiny muffler out the hole in the lower firewall. The O.S. was tested with a Top Flite 9 x 6, 10 x 4, and 10 x 6 prop and a Great Planes aluminum spinner nut is fed by a 6 ounce Du-Bro fuel tank. A Great Planes fueling port was also used.
For control, a Futaba SkySport T6YF 6-channel Sport radio using four channels to drive five servos was installed. The pair of Hobbico CS-12 micro aileron servos supplied power through a "Y" harness I fabricated out of two 24" servo extensions, plus a Futaba servo plug. The T-Craft has ample room for any size servos; I used mid sized Hobbico CS-35's to net a small weight savings over standard size servos. In a similar vein I used a miniature RCD-555 receiver to save some weight. The receiver and battery pack were installed aft of the servos to achieve the aft C.G. limit; these components could have been located well forward if needed to achieve the C.G. The switch and charge plug was installed using a Great Planes switch mount. This allows for radio charging without removing the wing. The struts are balsa, fitted with CA hinge material in the ends, and mounted using sheet metal screws, The review model ready to fly weight was 4 lbs., 4 oz. (68 oz.) which was within the advertised 3.75 lb-4.5 lb. target weight range.
The instruction manual shows low and hi rate control surface throws but does not suggest differential in the ailerons. I set up aileron at the high rate position and the down aileron at the low setting - works great.
For the first runs I had the FS-26 equipped with a 10 x 4 prop which I figured would be light enough to prevent overheating the new engine. After a couple of chokes, the O.S. started on the first flip, and a fast rich setting was chosen. It sounded pretty good so I leaned the high-speed needle a little more, but kept it off peak. Even with the grass cut short I had trouble getting up to speed, but we got airborne. Airspeed was too slow to do much, but the engine really sounded like it was running nice so I kept flying to get some time on the engine before bringing it in for an uneventful landing. Mindful of overloading the still new engine, I replaced the 10 x 4 prop with a 9 x 6. Rpm sounded about the same, and the engine did not sound like it was laboring. Immediately after breaking ground the change was apparent. The extra pitch increased the airspeed enough that everything got a lot better. On subsequent flights I got a little braver with leaning the mixture, ended up measuring 10,400 rpm on the ground. On a subsequent flying session, I broke the 9 x 6 on a landing, and went ahead and used a 10 x 6. Static rpm fell to just under 9,000, but again the airplane flies noticeably better with the larger diameter prop. My concerns with the power of the FS-26 evaporated, as the T-Craft is capable of scale looking maneuvers.
The T-Craft flies "bigger" than it looks, being very easy to fly smoothly. All positive G maneuvers that the full-scale T-Craft might perform are well within the repertoire. The recommended control throws work well, the T-Craft grooves well and is very responsive. I did a nice three turn spin the first try, recovering quickly following release of control inputs. Ditto with snap rolls, although I usually get 1-1/2 rolls. It holds energy well during the landing descent and slows to a crawl for touchdown.
My only real criticism of the T-Craft is of the landing gear system. It might be okay on a paved field, but even our very smooth grass field has been rough on the wire gear and fairings. The fairings are 1/8" balsa, MonoKoted and strapped to the wire landing gear leg using pieces of #64 rubber band glued in place. First off, the arrangement is hokey looking, and mars the overall clean appearance, and second, it simply did not hold up for me. The first flying session ended with one fairing flapping in the breeze, in the second flying session, after they loosened again, I simply removed them. The 5/32" wire landing gear seems extremely soft, and I am not going to be happy until I replace the wire gear with an aluminum unit.
In the last flight of the first flying session, I purposely flew out the tank just to see how much time I could expect from the FS-26 turning the 9 x 6 prop and using 6 ounces of fuel. Well, the engine finally shut off after 26 minutes of almost all-full throttle flight!
The T-Craft is another wonderfully designed and engineered kit and is well executed by Great Planes. There is a lot to build but it is not difficult for someone who has built a few kits before, and the builder will be rewarded with a very pretty little aerobat capable of realistic looking full-scale maneuvers. The model can be transported to the field assembled, and the FS-26 Surpass is a perfect match for the T-Craft, although I bet a 2-stroke .25 would also fly it well.Photos by Dennis Adamisin. Reprinted with permission.
January, 2002 R/C Modeler Magazine
Editor: Dick Kidd