Giantscaleplanes.com: Super decathlon

Model Airplane News, Jun 2001 by Yarrish, Gerry

An easy-to-assemble ARC giant

MODEL AIRPLANE NEWS

FIELD & BENCH

REVIEW

The Super Decathlon is the second in a series of almost-ready-to-cover (ARC) giant-scale airplanes from Giantscaleplanes.com. Distributed by Hobbies and Hells, the kit comes with a jig-built fuselage featuring "enginebox" construction. This feature provides a strong mounting base for the engine, landing gear and wing-tube mount in a single structure. A gelcoated fiberglass cowl, wheel pants and wingtips are included, as are formed, wooden lift struts, aluminum landing gear and basic hardware. The wooden tail surfaces come built, with beveled leading edges (LEs) on all control surfaces and with the control-horn hard points installed. The wing is completely built and ready for hinging. The servo pockets and servo-lead channels have already been cut out. The wing's LE is shaped, and the wing-mount-tube socket is already installed. There is little else to do with this kit except to install your engine and radio, attach the control surfaces and cover the model with your favorite brand of film or cloth.

GSP kits now include printed instructions, and you can download photo-illustrated instructions in a PDF file from the company's website: www.giantscaleplanes.com.

KIT ASSEMBLY

Work begins with the fuselage and the installation of the landing gear and the tailwheel assembly (not included). I installed a Cirrus Ventures scale tailwheel unit, which meant I had to install two 6-32 blind nuts in the plywood mounting plate already glued in the tail. I also had to install a few pieces of balsa around the tailwheel leaf springs so the covering could be blended around the gear attachment. I then installed the main landing gear and marked the position for the wing-strut attachment brackets. The gear and brackets are bolted to a plywood plate in the bottom of the fuselage. This area is then covered with a balsa cover (already built and sanded for you).

The next step is to install the wing-- mount tubes at the top of the cabin area. These are made of fiberglass and must be epoxied into place along with plywood doubters that strengthen their installation. It is best to temporarily install the wing panels and make sure that the root ribs align properly with the top of the cabin. Install the wing-attachment screws to hold the wings tightly against the fuselage side, then when they are in the correct position, epoxy the wing tubes into place and allow them to cure before you remove the wing panels.

At this point, it's a good idea to check the wing's dihedral and to fit the wing struts into place. In my kit, the prefabricated wood struts were too long and their ends did not align with the hardwood blocks already glued in the wing panels. To shorten the struts, I cut the extra-long aluminum attachment tabs at both ends of them. I then installed the struts with screws and blind nuts that I installed in the wooden attachment blocks. The kit includes formed wire jury struts, but I did not install them.

After the wing and struts were installed, I fitted and glued the tail surfaces to the fuselage. Slots are already cut for the surfaces, and it is very easy to epoxy them into place. Make sure that the horizontal stab aligns properly relative to the wing and that the vertical fin is 90 degrees to the stab. After the tail surfaces were in place, I installed the servos in the fuselage so I could make and install the rudder and elevator pushrods. I used two elevator servos and one for the rudder. Installation of the pushrods is much easier before the fuselage is covered. I also installed an internal tube so I could route the receiver antenna back to the tail. The last items to install in the tail are the bracing wires. These are not included in the kit, so I used a Sullivan tail-- bracing kit that includes all the hardware and braided metal cable to support the surfaces. The brass tube "hard points" for the brace wire attachment brackets are already installed for you. I used giant-scale CA hinges for all the control surfaces.

There is very little to do to the wing panels other than to install the aileron servos, hinge the ailerons and install the blind nuts for the wing-strut attachment. The wing tube sockets come already installed as do the attachment bolt's blind nuts in each root rib. The fiberglass wingtips come with flat molded flanges that are suppose to be glued to the wingtip rib after the wing is covered. For a more secure and better scale appearance, I sanded off the inner flange and slipped the tip over and around the tip rib then screwed the tips into place. For a better purchase for the tips, I glued 39-inch balsa to the tip ribs where the screws were located.

ENGINE INSTALLATION

The instructions suggest using a Zenoah G-23 gas engine to power the Super Decathlon. I tried several other engines-for example, a G-38, a U.S. 41 and a Brison 3.2-but these powerplants would have required cutting off the firewall and installing a new one farther back in the fuselage. The G-23 required only a 1/4-inch plywood shim attached to the firewall face to place the engine in the correct location. To support the bellcrank for the throttle linkage, I used an aluminum bracket attached to the engine using the carb attachment bolts. I also used B.H. Hanson throttle arm fittings to connect the throttle linkage to the carburetor. B.H. Hanson also sells the hopped-up version of the G-23 that I used in the model. I used a 16x8 Dynathrust composite prop, a Slimline muffler and a Tru-Turn aluminum spinner to complete the powerplant setup.