Sig Mfg. Co., Inc...401-7 South Front Street...PO Box 520....Montezuma, IA 50171-0520 Congratulations on your purchase of the SIG FOUR-STAR 20EP. For many years the SIG Four-Star series of low-wing sport airplanes have proven to be among the most popular and versatile at the flying field. Originally designed for 2-stroke glow engines, Four-Stars have also excelled with 4-stroke, gasoline, and now electric motors.
. Additional Items Needed The following items are not supplied in this kit but are needed to complete the airplane. Because of the wide variety of brands available and the influence of local preferences, the final choice of these items is left to you. In most cases, we will list what worked well for us in our prototype models. You should select equivalent items. BRUSHLESS OUTRUNNER ELECTRIC MOTOR 200-300 watts with a kv specification suitable for turning a 9x6E propeller.
. GLUES Choice depends a lot on you personal preference. We used Thin, Medium, and Thick SIG CA; CA Accelerator; Fine point CA applicator tips; and SIG Epoxy Glue (5-minute and 30-minute). BASIC MODELING TOOLS Screwdrivers, Pliers (regular, needle nose, flat nose), Wire Cutters, Scissors, Ruler, Pencil, Metal Straight Edge, Triangle, Flat Building Board, Hobby Knife with #11 Blades, Single-Edge Razor Blades, Wax Paper, T-Pins, Paper Towels, & Rubbing Alcohol (for cleaning off excess epoxy glue).
. The laser cut balsa and plywood parts can be identified using the "KEY TO LASER CUT PARTS". Mark the identification numbers on the corresponding parts before removing them from the laser cut sheets. Leave all the laser cut parts in the sheets until needed in construction. Then remove the pieces from the sheets carefully. Use a sharp #11 hobby knife to cut through any "tabs" that are holding the parts in the sheets. Lightly sand off any remainder of the tabs, flush with the actual edge of the part.
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. WING PANEL CONSTRUCTION We will build the wing in separate right and left wing panels, and then join the panels together after they are assembled. Let's start with the LEFT WING PANEL. To get started, tape or pin the wing plan to your building board. Cover the plan with a layer of waxed paper to keep glue from sticking to the plan. 1a. Cut four 1/8"x3/8"x36" balsa sticks down to 24" long for the Main Spars. Cut the four pieces of leftover stick to 9" long. These will be the Spar Doublers.
. 4a. Slip the 1/16"x1-1/2"x24" Balsa Trailing Edge Bottom Sheet in place under the back ends of the wing ribs. Slide it forward against the notches in the bottom of the ribs. Now pin the ends of all the wing ribs to the Trailing Edge Bottom Sheet and firmly to the plan. b. Pin the 1/14"x1/4"x24" Balsa Trailing Edge in place on top of the Trailing Edge Bottom Sheeting and up against the ends of the wing ribs. 5.
. 14. Cut a 1/2" dia. hole in the top sheeting just behind the main spar. This is for the aileron servo chord to exit the wing panel. 15. Use a large sanding block to sand any excess spar ends and sheeting flush with the W-1 rib. Use a sanding block large enough to sand the entire part at the same time. Work slowly to insure that the end rib remains flat and straight. 16a. Use a large sanding block to sand any excess spar ends or sheeting flush with the last W-4 tip rib. b.
. 22. Drill the center of the leading edge with a 1/4" dia. drill bit until the 1/4"x1-1/2" hardwood dowel can be slid into place in the notches in the W-1 ribs. The dowel should end up protruding about 5/16" out front of the leading edge. When satisfied with the fit, glue the dowel in place. 23a. Locate the laser-cut plywood WBP Wing Bolt Plate. Glue it in position on the bottom of the wing.
. d. Use a sharp #11 hobby knife to cut a groove in the leading edge to accept the Wire Joiner. e. Wipe the Wire Joiner clean with some type of solvent (paint thinner, mineral spirits, rubbing alcohol, etc.), and then glue it into the elevators with epoxy. Be sure to keep the leading edges of the two elevators aligned straight while the glue dries. f. Use a sanding block to bevel the leading edge of the elevators to a "v" shape, using the hinge line as a guide.
. FUSELAGE CONSTRUCTION 31. Remove the balsa Fuselage Sides from laser-cut sheet no. 5 and the FD-1 Doublers from sheet no. 3. Use slow drying glue to laminate one doubler to each fuselage side, making sure to make a LEFT and RIGHT assembly. Also make sure that you have the doublers properly positioned on the fuselage sides - 2 points to pay particular attention to are the wing saddle and the bottom of the nose those edges should match up perfectly.
. 37. Install the balsa fuselage bottom piece FBT-2, gluing it to all its mating parts. 38. Install the plywood TWM tailwheel mount. 39. At the front of the fuselage, carefully lift the front portion of the fuselage top up to fit between the fuselage sides. Remember back in step 34 you cracked the top slightly along the dashed cut lines so it can make this bend, When you have it fitting well between the side, glue together with a few drops of thin CA glue. 40.
. 46. Glue on plywood top former FHR. Note on the plan that FHR tilts back towards the rear of the fuselage. There should be approx. 2-3/8" between the top of FHR and the top of former F-4T. 47. From 36" long balsa stock, cut to length and glue in place the five 3/32"x3/16" stringers for the top rear of the fuselage. When glue is dry, sand the ends of the stringers flush with the front of former FHR and the rear of former F-6T. 48. Glue in place the plywood fuselage top formers T-1 and T-2.
. c. When glue is dry, sand the protruding ends of the pushrod tubes flush with the fuselage sides. 54. Test fit the wing onto the fuselage, using the 10-32 x1" long Nylon Wing Bolt provided. It should go on easily without binding. Adjust the dowel hole in former F-2 and/or the wing saddle slightly if necessary to achieve a proper fit. 55. Finish sand the entire fuselage.
. Covering The Fuselage The fuselage should be covered with 7 separate pieces of covering material, in the order described here: Fuselage Bottom - 2 pieces, front and rear Fuselage Sides - 2 pieces, left and right Fuselage Top - 2 pieces, front and rear Hatch - 1 piece All seams should overlap at least 3/16".
. Allow the decals to set overnight to finish drying. Once dry, they will be solidly adhered to the model. When completely dry, wash off any soapy smears with a soft clean wet rag. Hinging The Control Surfaces The hinges in this kit are designed to be installed with Thin CA glue. Thin CA (any brand) is the ONLY type of glue that can be used on the hinges - do not use epoxy or any other type of glue! 56. Let's start with hinging the elevators to the stabilizer. a.
. i. The rudder is hinged in the same manner as the other parts, but it is easier to install AFTER the fin has been glued onto the fuselage. For now, go ahead and cut the slots for the hinges in the fin and rudder, but do not glue them. Set them aside until later. VERY IMPORTANT: It's critical that you only make one application of glue to each side of the hinges.
. 59a. Install the 3/4" dia. Tailwheel on the axle of the formed Tailwheel Wire, using the 1/16" id Wheel Collar provided. b. Slide the plastic Tailwheel Bracket onto the shank of the tailwheel wire. Be certain that you have the bracket on right side up. c. Using a needle nose pliers, bend the top of the tailwheel wire back 90 degrees, as shown on the plan. 60a. Hold the tailwheel assembly in place on the bottom of the fuselage, familiarizing yourself with the installation - see plan.
. Radio Installation 65. Mount a Nylon Control Horn on the bottom of the left elevator using two #2 x1/2" Sheet Metal Screws provided, as follows. a. Note that there are right and left Nylon Control Horns. Study the plans and photos carefully to identify which type you should use on each control surface. Use a right control horn for the elevator. b. Cut the Control Horn and the Retainer Plate apart.
. d. Unhook the rear of the elevator pushrod from the control horn and slide the pushrod as far forward as possible. Cut off the servo end of the pushrod wire at the longest mark. e. Bend the end of the pushrod wire over 90 degrees at the remaining mark (the first mark you made back in step b.) Make the bend as sharp as possible. f. With a needle nose pliers, make another 90 degree bend back the other way, on the servo side of the mark - forming a "Z" bend. Make the bend as sharp as possible. g.
. d. Install the z-bend end of the finished aileron pushrods in the servo arms. Snap the RC Links to the aileron control horns. e. Plug both aileron servos into your radio system using a Y-Harness chord. Make sure the aileron trim is neutral, and then adjust the RC Links to align the ailerons in neutral position. Note: Your kit includes a plywood piece called APG, which stands for Aileron Positioning Guide.
. 78a. Mount your motor on the firewall with appropriate screws. Be sure to locate the centerline of your motor with the thrust line. b. The motor wires can be fed back through any of the holes in the firewall whichever one is most convenient for your motor configuration. Leave all of the holes in the firewall open. They provide cooling air to the battery pack. 79. Connect your ESC to the motor wires, being very careful to get the polarity correct (red to red, black to black).
. e. Remove the cowling from the fuselage. Open up the four holes in the cowling to allow the mounting screws to pass cleanly through the plastic (a #45 .082" drill bit is perfect). f. On the fuselage, run the mounting screws in and back out of the holes a couple times to create good threads in the wood. Note: If the screws ever get to loose in the wood, take the screws out and place a small drop of Thin CA glue in each hole. Let dry thoroughly. Then run the mounting screws in and out a few times again.
. 88. The propeller and spinner should NOT be installed on the motor for this initial test - for safety! a. Slowly advance the throttle stick on the transmitter. The motor should start turning. If not, your throttle channel needs to be reversed on the transmitter. b. Now make sure the motor shaft is moving in the correct direction. When viewing the fuselage from the rear to the front - as if you were sitting in the cockpit - the motor shaft should turn clockwise when throttle is applied.
. First Test Flight The Four-Star 20 is a fun airplane to fly, but it is not a basic trainer. If you have no previous R/C flying experience, we suggest that you not attempt to fly this model without the assistance of an experienced R/C pilot. Contact your local R/C club or ask your hobby dealer for the names of good fliers in your area and a suitable location for flying. Choose a calm day with little or no wind for the Four-Star 20's first test flight.
. Customer Service SIG MFG CO. is totally committed to your success in both building and flying the FOUR-STAR 20EP design. Should you encounter any problem building this kit, or discover any missing or damaged parts, please feel free to contact us by mail or telephone. SIG MFG. CO., INC. 401-7 South Front Street PO Box 520 Montezuma, IA 50171-0520 SIG MODELER S ORDERLINE: (to order parts) 1-800-247-5008 SIG MODELER S HOTLINE (for technical support) 1-641-623-0215 SIG WEB SITE www.sigmfg.
