SIG Four-Star 120 Building And Flying Instructions
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SIG Four-Star 120 Building And Flying Instructions

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Introduction
First, some history. In June of 1989, SIG Mfg. introduced the FourStar 40 to the modeling world. No, it wasn't an overnight
success, but its reputation quickly spread. Novice flyers suddenly looked like pros and experts couldn't believe how slow it could
land without stalling. Instructors began calling us with stories about training people to fly R/C with the FourStar 40, even though
it's never been promoted as a trainer. Clubs even began using it for one-design pylon races!

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Summary of Contents for SIG Four-Star 120

  • Page 1 Introduction First, some history. In June of 1989, SIG Mfg. introduced the FourStar 40 to the modeling world. No, it wasn't an overnight success, but its reputation quickly spread. Novice flyers suddenly looked like pros and experts couldn't believe how slow it could land without stalling.

  • Page 2: Radio Requirements

    Personally, I've had more fun with the Four-Star 120 than any model I can remember. There's no doubt in my mind that you'll enjoy it just as much!
  • Page 3 CA. An accelerator spray and debonder are also available and are described below. Sig CA Thin - Watery in consistency, thin CA should only be used when the two parts to be joined are in perfect contact with zero gap.
  • Page 4 In addition to these instructions you are reading now, the booklet "The Basics of Radio Control" has been included with this kit as a reference for installing the engine, fuel tank, and radio in the Four-Star 120. It also contains very important information for preparing your model for flight.
  • Page 5 Die-Cut poplar Plywood (Lite-Ply) 2 1/8"x6-3/4"x48" Rear Fuselage 2 1/8"x6-3/4"x48" Front Fuselage Side, 1 1/8"x5"x48" FT, TWM, T-2, 1 1/8"x5"x38" FBR, HR, APG Side, Wingtip, Wing Dowel Fuselage Doubler, Nose Tripier, Aileron T-3, Stab Support Support Servo Mount, SRS 1 1/8"x5"x24" FBF, Tank Floor, F- 1 1/8"x6"x24"...

  • Page 6: Wing Construction

    WING CONSTRUCTION Building The Wing Panels Construct four main spar assemblies by gluing the four 1/4"x1/2"x16" hardwood spar doublers to the four 1/4"x1/2"x42" hardwood main spars. Use epoxy for this step, and make sure the spars are kept straight while drying. Any bends or twists built in now are there to stay! a.
  • Page 7 3/32"x3" balsa sheet provided in the kit. Trim and sand the sheet to fit, then glue it in place. Sig-Bond is recommended for gluing all of the center sheeting to the ribs and spars because it will be easier to sand the joints smooth later.

  • Page 8: Joining The Wing Panels

    11. Install the bottom center sheeting except for the two areas shown in the photo. Cut pieces from the 3/32" x 4" balsa that you used earlier. a. Cut off and sand the spars, leading edge, trailing edge, and sheeting at both ends of the wing, flush with the end ribs.

  • Page 9: Finishing The Wing

    Finishing The Wing NOTE: Complete the steps in "Mounting The Wing To The Fuselage" before proceeding. a. While you still have access through the bottom of the wing, check the glue joints around the wing hold-down dowels and the dihedral brace. If necessary, apply another coating of epoxy to the joints.

  • Page 10: Aileron Servo Installation

    Aileron Servo Installation The ailerons on the Four-Star 120 are operated by two servos mounted separately in each wing panel (see "RADIO REQUIREMENTS" earlier on in these instructions). 25. Cut two hatch rails from the special-cut 1/4"x1/2"x12" basswood stick provided in the kit.
  • Page 11 a. Make an aileron pushrod as shown on the plan from a 4-40 x8" threaded rod, a 4-40 solder clevis, and a 4-40 R/C link. The actual length of your pushrod may have to be altered slightly depending on the shape of your aileron servo. b.

  • Page 12: Fuselage Construction

    FUSELAGE CONSTRUCTION Fuselage Subassemblies Before starting fuselage construction, there are a few subassemblies that should be built and set aside until needed. This is done to avoid interruptions during the flow of fuselage construction. a. Glue together the two die-cut 5/32" plywood F-1 pieces using Kwik-Set epoxy or slow CA.
  • Page 13 a. Notice that the die-cut lite-ply former F-2 has two dimple marks which are used to locate the holes for the wing hold- down dowels. Glue F-2D to the die-cut lite- ply former F-2 so that the dimples remain showing. b.
  • Page 14 a. Install the landing gear mount to the fuselage by gluing it firmly to the sides, the doublers, and the bottom of F-2. b. Bevel the bottom edge of F-1 as necessary to allow FBF (Fuselage Bottom, Front) to seat properly in its grooves on the bottom of the fuselage.

  • Page 15: Mounting The Wing To The Fuselage

    Mounting The Wing To The Fuselage NOTE: The wing must be completed through step 18 before proceeding. a. Trial fit the wing to the fuselage. Align the wing (see the General Alignment Diagram on page 20 of "The Basics of Radio Control") and make accurate pencil marks on both the wing and fuselage so that the wing can be returned to the same position later.

  • Page 16: Servo And Pushrod Installation

    a. Remove the wing and tap the wing hold-down blocks with a 1/4-20 tap. Apply a few drops of thin CA to the holes to strengthen the threads. When you are absolutely certain that the CA has cured, clean up the threads by re-tapping the holes.

  • Page 17: Tail Construction

    59. Now is a good time to install the .130 o.d. nylon outer tubing (clear) for the throttle pushrod. Route the tubing with as little curvature as possible, and support the aft end with a scrap balsa standoff. A SIG pushrod connector is supplied in the kit to hookup the cable to the throttle servo arm.

  • Page 18: Fin And Rudder

    Draw a line on both sides of the fin trailing edge 3/8" below the fin base. c. Apply slow CA or Sig-Bond to one entire side of the fin frame except for the area below the line that you have just drawn.
  • Page 19 a. Tape the rudder to the fin so that BUILDER'S TIP: its bottom edge is aligned with Two #2 flat washers are included in the kit to act as retainers for the tailwheel. the fuselage bottom. Of course, you can use 3/32" wheel collars (not included in kit), but the soldered b.
  • Page 20 (glass) resin, sanded between coats. Finish off the engine area with a few coats of colored Sig Supercoat Dope.
  • Page 21 Its toughness and relatively low cost make it ideally suited to giant scale and giant sport models. One large package of Koverall (SIGKV003, 48" x 5 yds.) is plenty of material to cover the Four-Star 120. It can be applied to the structure using dope or Sig Stix-It, and heat-activated adhesive.

  • Page 22: Applying Decals

    (applied with a small brush) before applying the trim color. A final coat or two of clear dope over the color dope will add a nice gloss to the finish. Stick with Sig products from the start and you'll be rewarded with a classy finish that is rugged and easy to repair.

  • Page 23: Final Assembly

    a. To set the hinge gap, deflect the elevators to the maximum amount needed. For best control response, the gap should be as small as possible but big enough to allow full movement of the control surface without binding. b. EASY HINGES were designed to use THIN CA (any brand) for maximum glue penetration.

  • Page 24: Engine And Fuel Tank Installation

    Dress up the bottom edge of the canopy by applying 1/4" striping tape (like Sig Super Stripe), half on the canopy and half on the fuselage. Finish off the canopy with more 1/4" striping tape applied to the raised frame and at the back edge.

  • Page 25: Radio Installation

    Like most SIG kits, the fuel tank in this model is installed from the rear of the fuel BUILDER'S TIP: tank compartment rather than through a removable hatch. This choice was made for several reasons. A hatch opening makes the nose weaker and it's very Here's a handy trick that you can use difficult to keep oil from leaking in around a hatch.
  • Page 26 FLYING Like it said at the beginning, the Four-Star 120 was designed with flight performance as one of its top priorities - and we weren't disappointed! If you've never flown a plane that is this large, you are definitely in for an eye-opener. Lots of modelers will tell you that "bigger flies better"...
  • Page 27 Fly safe! You may need the room to recover from a messed up maneuver. When landing, the Four-Star 120 may tend to "float" a bit more than models you have flown in the past, so be ready to go around if it looks like you're going to overshoot the runway.
  • Page 28 The top view and side view drawings are provided for modelers who wish to develp their own personalized color and trim scheme for the FOUR-STAR 120. Make several copies of this drawing so you can draw out a few different ideas before...
  • Page 30 LIMIT OF LIABILITY: In use of our products, Sig Mfg. Co.'s only obligation shall be to replace such quantity of the product proven to be defective. User shall determine the suitability of the product for his or her intended use and shall assume all risk and liability in connection...

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