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The "Classic" from CheckerboardAir is a limited edition balsa and lite-ply kit, designed by Allan Flowers, and advertised under the headline "Announcing the End of the Boring Trainer." The plane has a sleek, almost aggressive, modern look, and definitely stands out at the field against the background of Cessna-like trainers. The plane sports a semi-symmetrical airfoil, a partially cowled engine, and a removable horizontal stab. The kit arrived in a large flat box, labeled "Fragile" in big letters with a Magic Marker. This apparently impressed the UPS man, because the condition of the contents was perfect. The laser-cut wood was essentially perfect, and the hardware high quality. The kit includes all the hardware needed other than the fuel tank, engine mount and wheels. It even includes the black Monokote trim sheet for the "windows", plus a small piece of clear Monokote used to create a real window into the fuel compartment. This is a nice touch, because it avoids the requirement for the kit builder to buy an entire roll of clear Monokote. The manual is very well written, covering all facets of construction. The style and tone is that of a master builder giving instructions. Most appreciated were the complete instructions for mounting servos and assembling control rods, an area where many kits leave the builder on his own. Many hints are included for the more difficult processes such as shaping the leading edge, and sheeting the wing surfaces. The manual uses no photographs. Instead, it is profusely illustrated with ultra-clear CAD drawings, examples of which are available on the company's web site. The wing is built conventionally, over the plans, on a flat building board. Parts and instructions are included for building the wing with either one or two aileron servos. The laser-cut pieces fit together absolutely perfectly, with just a bit of snugness. In fact, the perfect fit of the laser parts led to a building error. The kit comes with lite-ply jigs that hold the wing halves in position while being joined. These were not used, since the halves joined so perfectly they were not thought needed. After the epoxy dried, it was noticed that the wing had sagged as the epoxy dried and ended up with about 1" less dihedral than intended. The resulting wing still flies beautifully, but it gets a lot of comments at the field. Another change made was in fiberglassing the wing joint. The manual calls for 3/4" wide nylon tape, but 4" wide light-weight fiberglass fabric and epoxy finishing resin was used instead, so that the rubber bands that hold the wing ride on epoxy, rather than soft balsa. Because of the high quality manual and laser-cutting, this kit would make a suitable first kit in all respects except one, the engine mounting, which is quite difficult. The engine and mount must be selected and on hand before starting to build the fuselage, and they must meet very specific requirements. First, the mount must include provisions for the nose gear when the engine is mounted side-ways, which is somewhat rare. Second, since the engine is attached to the mount before the mount is attached to the firewall, there must be a way to get to all the mount screws with the engine in place. There was no way to do this with an OS .46 FX, because the remote needle valve prevents access to one of the mount screws. After consulting with the kit manufacturer, a Thunder Tiger .46 Pro was selected, and a Great Planes engine mount used. The Thunder Tiger is ideal because the needle valve does not have to be extended in order to clear the cowl. Once the engine and mount are selected, care must be used in drilling the holes in the firewall, so that the engine will fit entirely within the nose of the aircraft. Being off by 1/8" could be disastrous, so it is well to take the time to get it right. There is a cowl reinforcement piece that may be required, and its thickness must also be considered. Once the nose configuration is settled, the rest of the fuselage is easy. It is assembled without glue and only a little masking tape is required due to the excellent fit of the parts. Once the fuselage is assembled and perfectly square, it is then glued with medium CA. The only change made to the fuselage was to substitute 1/4" wing hold-down dowels for the 3/16" ones provided. The last operation on the fuselage is to form the cowl out of 1/32" plywood, and cut it and the fuselage side so that the engine and mount assembly can be inserted from the bottom of the plane. Small holes in the front of the cowl are required, for access to the screws that hold the mount to the firewall. A Dremel tool is handy for this step. In another change from the plans, the entire inside of the engine compartment was reinforced with thin fiberglass and epoxy finishing resin. This turned the thin plywood into a tough flexible material that has held up well despite the thinness in some areas. The servos are mounted in the lite-ply carrier provided in the kit. The receiver is cleverly suspended between rubber bands in the same carrier. Complete instructions are provided for all the linkages, and the hardware supplied fit perfectly. The plane is relatively easy to cover, due to the big flat surfaces and the removable stab. The plans include diagrams for the checkerboard on the tail surfaces and the underside of the wing. CA hinges are provided for the control surfaces. Decals for the "Classic" logo are provided, but the orange and deep blue didn't fit the selected color scheme, so the letters were traced and cut out of Monokote. The plane was covered in Copper Pearl and Metallic Plum Monokote, which looks great on the ground, but lacks contrast in the air. An experienced DC/RC pilot took the plane up for its maiden flight. Absolutely no trim adjustment was required, a tribute to the perfect fit of the laser parts, and scrupulous use of a straightedge to set the neutral position of the control surfaces. An initial problem with flutter was solved by ensuring that the elevator and rudder control rods were as straight as possible. This is a great flying plane with a unique appearance. It is unlikely, despite the advertisement, that anyone would actually use this plane as a trainer. It is just too nice to take the beating a trainer would. However, as a second plane, it is ideal. It is rugged, its light wing loading (18 oz / square foot) allows it to float in for landings, and its semi- symmetrical airfoil allows it to be more aerobatic than a flat-wing trainer. The one suggestion for the kit designer would be to include an option to bolt on the wings. |
