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SIG Somethin' EXTRA N477SC, Instruction Book, Page: 7 / 29

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SIG Somethin' EXTRA N477SC Instruction Book Download Page 7

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WING CONSTRUCTION

 
Note: The full size plan depicts both right and left wing panels from the TOP view. These wing panels are initially built 
directly over the plans and are not removed for the bottom sheeting until Step 12. These instructions assume you are 
building both wing panels at the same time.

 
1.

 
In this step, you need to prepare several parts for the construction of both wing 
panels. Begin by locating four (4) 1/4" sq. x24" balsa sticks and four (4) 1/4" sq. 
x11" balsa sticks from the kit contents. These will become the top and bottom 
wing spars. Trim the four 11" sticks to a length of 10-5/8" each. Glue one the 10-
5/8" pieces onto one end of one of the 24" spars to create a laminated spar. 
Repeat this procedure with the remaining three spars. Note that the laminated 
ends of each spar, now measuring 1/4"x1/2" cross-section, will be the inboard 
ends. 
Next, locate the two (2) ply W-1 root ribs and remove the round fillers in each. Set 
the two larger, 15/16" dia. fillers from each rib aside, as these will be used to cap 
the female wing tubes. 

 

Remove the 7/8" dia. x15-1/4" aluminum wing joiner tube from the 16 length of phenolic impregnated female tube. Use a 
fine-tooth razor saw or power jig-saw to carefully cut two 6 lengths of female tubing, setting aside the remaining 4 piece for 
later use in the fuselage. Carefully glue one of the 15/16" dia. ply fillers (just removed from the W-1 ribs) onto one end of 
each of the two 6 female wing tubes. Lightly sand the outer edges of these caps to match the outside diameter (O.D.) of 
the female wing tubes. Set these tubes aside for use in the following steps.

 
2.

 
Pin the bottom laminated spar carefully in place over the plan, with the laminated 
end at the inboard location, flush with the outer face of the W-1A rib location. Pin 
the spar in place from the top to allow the pins to be removed after the top 
sheeting is in place. The 1/4 sq. laminated length should be sitting on top of the 
1/4 sq. full span spar at this point. Use a straight edge to ensure the spar is 
positioned exactly straight over the plan for the full span of the panel.

 

 

 

BUILDERS TIP: When pinning ribs to 
your work surface, pin them in place 
through each side of the removable 
alignment/standoff tabs on the bottom 
rear.

 
3.

 
From the laser-cut parts in your kit, locate wing ribs W-1A through W-7 and the 
two plywood aileron servo trays that fit between ribs W-3 and W-4. Check each 
rib to make sure that each of the laser cut holes are cleared out - vent holes, etc. 
Now is also a good time to make sure your aileron servos fit into the standard 
servo cut-outs provided in each of the ply servo trays. If required, trim these trays 
as needed to allow your servos to fit nicely. This is also a good opportunity to drill 
the aileron servo mounting screw holes into the trays. We suggest using a power 
drill for this operation and backing up the trays with scrap ply to avoid splintering. 
Once this is done, set the trays aside for later installation. 
 
Glue the W-7 tip rib in place onto the spar. Use a 90 deg. triangle to make sure 
the rib is exactly upright and that it is in place exactly over the plan - pin in place. 
Glue W-6 and W-5 in place in the same manner - making sure they are exactly 
upright and over the plan. Pin these ribs in place as well. Glue rib W-4 in place 
onto the 1/4" sq. spar and against the outer face of the 1/4" sq. spar doubler. 
Glue W-3 in place. Apply glue to the two tabbed outer edges of the aileron servo 
tray, spread the W-4 and W-3 ribs a little and fit the servo tray in place into the 
slots provided in each of these two ribs. Close the ribs to capture the servo tray 
and pin the ribs in place to your work surface.

 
4.

 
Glue ply rib W-2 in place, again using a triangle to ensure that it is exactly upright at 90 deg. and exactly over the plan. Ply 
rib W-1A is now glued in place over the spar. 
IMPORTANT: Take your time and be careful installing this rib. To provide the correct relationship to the fuselage, W-1A 
must be positioned at 90 deg. upright and exactly lined up over the plan.

 
5.

 
Temporarily install the top spar in place into each rib - do not glue. Lay a piece of balsa wing sheeting over the top spar 
and ribs and place weights (magazines, metal bars, etc.) on top of the sheeting to make sure the panel is flat to the 
building surface. Glue the 1/4" sq. x24" balsa trailing edge stock in place to the end of each wing rib. Pin or fixture in place, 
making sure it is correctly in position and straight. With the wing panel still weighted in place, glue the shaped 3/8"x24" 
leading edge in place into the notches at the front of each rib, rounded edge facing forward - pin or fixture in place.

Summary of Contents for Somethin' EXTRA N477SC

Page 1: ......

Page 2: ...ered to provide you with an enjoyable building experience The plans were developed using our powerful CAD Computer Aided Design system To insure absolute accuracy the individual parts themselves were then generated using these same plans through a path directly to our computerized laser cutting system This methodology produces incredible accuracy minimizing and or eliminating the need to prepare p...

Page 3: ...nate fumes Sanding Blocks And Straight Edges It has been correctly said that the difference between a good model and a great one is sandpaper and the knowledge of how to use it In these instructions you will note that we often mention sanding blocks T bar sanders etc You will definitely need several sanding blocks to build this model If you don t already have one do yourself a favor and purchase a...

Page 4: ...2 6 32 x1 1 2 Round Head Bolt Wheel Axles 4 6 32 Lock Nuts Wheel Axle Assembly 2 6 32 Hex Nuts Wheel Axle Assembly 7 6 32 Blind Mounting Nuts Landing Gear Motor Mount Attach 8 2 x1 2 Pan Head Screws Control Horn Attach 6 6 Metal Washers Wheel Axle Assembly 1 Piece of 1 x8 Fiberglass Tape 18 SIG Easy Hinges Ailerons 8 Elevators 6 Rudder 4 Miscellaneous Parts 1 7 8 O D x15 1 4 Aluminum Tube Wing Joi...

Page 5: ...od Ink will invariably leach through your film covering material and could ruin the finish Use a well sharpened 2 pencil for best results Use a small piece of masking tape and a pen to identify each of the various laser cut parts To do this refer to the Key To Laser Cut Parts drawings Note that the outlines of the actual laser cut parts themselves have been purposely interrupted at various points ...

Page 6: ... ...

Page 7: ...bs on the bottom rear 3 From the laser cut parts in your kit locate wing ribs W 1A through W 7 and the two plywood aileron servo trays that fit between ribs W 3 and W 4 Check each rib to make sure that each of the laser cut holes are cleared out vent holes etc Now is also a good time to make sure your aileron servos fit into the standard servo cut outs provided in each of the ply servo trays If re...

Page 8: ...ed spar provides gluing surface for the center sheeting and the cap strips We have found the easiest way to glue the leading edge sheeting in place is to do it in two steps 1 Start with the leading edge glue joint where it mates to the top rear face of the 3 8 leading edge Apply a bead of glue along the entire length of the sheeting on its front edge only Fit the sheeting in place to the top rear ...

Page 9: ...he exposed back half of the spar Carefully position this sheet to minimize high spots gaps etc Use weight or pins to secure in place and spray with accelerator BUILDERS TIP When edge gluing two pieces of sheeting off the structure it is always best to sand the resulting joint smooth on both sides with a sanding block before gluing the sheet in place This practice minimizes high and low spots bumps...

Page 10: ... to the contours of the wing Sand the face of W 1A smooth avoiding contact with the two exposed tube ends Trial fit the ply W 1 rib in place to W 1A NOTE When the W 1 rib is in place with the female wing receptacle tube inserted into its corresponding hole the rear 3 16 dia wing locating dowel holes in both W 1 and W 1A will line up exactly Use the 3 16 dia dowel in your parts bag as a temporary f...

Page 11: ... the laser cut aileron control horn holes top and bottom to reinforce these areas Lay the cut piece of fiberglass in place over the holes and flood the tape with thin CA glue until the weave is full Allow to set and repeat the process with the other side of the aileron Repeat the process on the remaining aileron Use sandpaper to lightly sand the glass smooth BUILDERS TIP After cutting the fibergla...

Page 12: ...cedure with the two holes on each side of the stab Save the excess drilled dowel material as it will be used during fuselage construction 30 The tail group is now basically assembled We suggest that now is a good time to sand these assemblies In order to sand the fin rudder and stabilizer elevators assemblies uniformly use masking tape on one side only to temporarily attach the rudder to the fin a...

Page 13: ...ermine the required spacing between the two engine mounts to fit your particular engine Use a pencil to mark that spacing onto the face of the firewall Example If the width of your engine s case is 1 3 8 then divide that figure in half 11 16 and mark the face of the firewall with the 11 16 measurement on each side of the vertical centerline Use a triangle to draw two parallel lines one at each 11 ...

Page 14: ... these openings as required and to drill the required holes for mounting them to the tray Once the tray is ready glue it in place to the fuselage side just above the 3 16 dia rear wing locator dowel hole and to F 4 engaging the rear tab on the servo tray in the top cut out in F 4 IMPORTANT With both fuselage sides properly in place the rear 3 16 dia holes for the wing root locating dowel on each s...

Page 15: ...r fuselage formers Because of the rudder and elevator pushrod orientation they must be installed in the correct direction The cross sections on the plans show these formers facing forward toward the nose this is the correct position for each former Locate the 1 4 x1 2 leftover length of balsa that you were asked to save in Step 27 This piece of scrap will now be used as a spacer at the rear of the...

Page 16: ...op Rear sheet FTR in place from the top rear face of F 4 to the front face of F 7 This is easy to do by first fitting FTR securely in place to the fuselage and using thin CA glue with a thin applicator extension applying the glue from the inside of the fuselage Glue the Fuselage Stab Mount FSM in place behind F 7 into the fuselage sides Lightly sand the top surfaces of these parts smooth with a sm...

Page 17: ...space the rail 1 16 above the fuselage side and secure it with pins from the outside of the fuselage Take your time and make sure it is uniformly spaced 1 16 above the side of the fuselage Repeat this process on the opposite side with the remaining rail Glue the ply hatch base onto the tops of each rail aligning its edges with the fuselage sides and holding its forward end with the 5 16 dia hole i...

Page 18: ...nto the fuselage This is done by first engaging the rear dowel into the locating hole in the F 4 Cap centering the locating rails and pressing the hatch in place There should be very little gap at the front of the hatch If the fit seems too tight lightly sand the face of F 2T 68 Locate the remaining length of 5 16 dia center drilled dowel As shown on the plans this dowel fits into the front of the...

Page 19: ... fuselage with rounded edges on the bottom and at the nose Take your time and do a good job At this point you need to make a decision regarding the covering technique for this model We are aware that some modelers prefer to cover the stabilizer fin and fairing blocks separately off the fuselage and glue them in place afterwards While this technique may work for some we prefer to glue these surface...

Page 20: ...ch the two motor mount arms to the firewall Without the muffler installed place your engine onto the motor mounts and locate it to the previously drilled holes with at least two of 6 32 x1 bolts without nuts You will likely note that in order for your engine to fit in place with the muffler attached the right fuselage side must first be trimmed to accept the manifold We suggest about 1 8 clearance...

Page 21: ...e cover of this kit is fairly easy to accomplish In the case of the wing panels stabilizer and fin we used the plans themselves to develop the color separation lines patterns These patterns were drawn on drafting vellum directly over the plans taking care to keep the color seams over solid wood The pattern was then taped over both colors of covering film one underneath the other and cut using a me...

Page 22: ...ng panels using the same method as the elevators Again be careful to make sure that the correct aileron is hinged to its correct wing panel control horn holes on the inboard side of W 3 NOTE The rudder will be hinged using the same methods in this section after the tailwheel has been installed in the FINAL ASSEMBLY section FINAL ASSEMBLY Canopy Some builders may wish to install a pilot If so it sh...

Page 23: ...or a really nice look use a good metal polish such as Simichrome or Flitz to polish these support wires and solder links to a high luster chrome like finish d The two lower support arms are made in the same way The only difference is that the inboard solder link arms will overlap each other and be attached to the fuselage with a single 2 56 x3 8 bolt passing through the holes in each link and into...

Page 24: ...m into the mounting plate f Apply glue to the inner face of the mounting plate and glue it inside the wheel pant with its two mounting holes lined up with the two holes drilled in the pant use the 4 40 x3 8 bolts to tighten the plate to the inside surface of the pant g Note that if any of the ply mounting plate is exposed in the pant slot it needs to be trimmed away with a sharp 11 blade to match ...

Page 25: ... nylon tie wrap through the holes provided in the tray This method is simple lightweight and effective It also provides excellent access to the receiver servo receptacles with the canopy hatch removed The receiver antenna is fed through the antenna tube exiting at the bottom rear of the fuselage We would also suggest using the radio manufacturer s antenna strain relief included with your system As...

Page 26: ...lder the link in place and reconnect the completed pushrod to the aileron servo and nylon control horn 95 Locate the 18 length of metal throttle cable a solder link a nylon R C link and the 2 56 x3 4 threaded brass coupler Slide the brass coupler onto one end of the cable and solder it in place Thread the nylon R C link in place onto the threaded brass coupler From the firewall side insert the cab...

Page 27: ... independent movement of each aileron to control roll This is a versatile mixing feature as long as the pilot maintains elevator input as required ELEVATOR FLAP ELEVATORS and FLAPS Elevator to Flap mixing is also a good feature It interfaces the elevators to the flaps allowing both surfaces to work together When mixed together the flaps travel downward while the elevators travel upwards at a progr...

Page 28: ...l hang lower This can have a negative effect on how this or any other model flies and will show up in certain maneuvers It should be corrected The quickest fix is to add small stick on weights to the lighter wingtip until model hangs level A neater method is to cut a small hole in the wingtip place the lead inside securely and recover the area No matter how you do the job a laterally balanced mode...

Page 29: ...nited States is the ACADEMY OF MODEL AERONAUTICS commonly called the AMA The AMA SAFETY CODE provides guidelines for the safe operation of R C model airplanes While AMA membership is not necessarily mandatory it is required by most R C flying clubs in the U S and provides you with important liability insurance in case your R C model should ever cause serious property damage or personal injury to s...

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