The fuselage doublers are now glued to the fuselage sides to create a LEFT side and a RIGHT side. This step is important because several components must be carefully aligned. Therefore, we suggest that you use a slower setting glue, such as an aliphatic resin like the SIG-Bond product. Using this glue gives plenty of time to position parts correctly. Start by fitting these parts together to see how they relate to each other - again make sure you are working with a LEFT and RIGHT fuselage side and doubler. Note that both the doublers and the fuselage sides have holes in them to accommodate the female wing tube - this is the forward positioning locator for the doubler. The rear locator is the 3/16" dia. hole in both parts which accepts the 3/16" dia. rear wing locator dowel. The easiest and most accurate way to position and glue the fuselage doublers in place is to use one end of the remaining 4" length of female receptacle tube to position the doubler to its fuselage side. Then use one end of the 3/16" dia. dowel to position the rear of the doubler to the fuselage side. Once the doubler is in place against the fuselage side, pin or weight it in place, remove the tube and dowel and allow the assemblies to dry.


Start with either the right or left fuselage side and glue firewall F-1 in place, using a 90 deg. triangle to position it exactly upright to the fuselage side. Use the same technique to glue formers F-2 and F-4 in place.
NOTE: Former F-2 has a laser cut hole on one of its sides to accept the throttle cable housing tube. F-2 can be installed with this hole on either the right or left side, depending upon which side the carburetor throttle lever is located on your engine. Check this first before installing F-2.


Before gluing the 1/8" ply servo tray in place, take a moment to make sure your servos fit into the laser cut openings provided. With the servo tray not yet installed, it is easy to adjust 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 side of the fuselage, must be clear. Later, when this dowel is installed, it must pass through these two holes and fit directly beneath the servo tray, as shown on the plans. If you see any interference from the servo tray, DO NOT adjust the holes, adjust the servo tray if required.


With the exception of the 1/8" tank floor, all parts are now in place to accept the opposite fuselage side. Trial fit the fuselage side in place, engaging F-1, F-2, the servo tray and F-4 in their respective slots. The fuselage side should fit perfectly without any need for trimming. Remove the fuselage side, apply glue to the mating edges of the above parts and fit the fuselage side back in place, using weights or pins to hold it perfectly flat. Apply accelerator to the glue joints.


Glue the 1/8" ply forward hatch mount in place, between the fuselage sides and against the upper rear face of F-2 (the 4-40 blind nut should be underneath the hatch mount, as shown on the plans). On the bottom of the fuselage, glue the 1/4" ply landing gear mount in place, between the fuselage sides and against the rear bottom edge of F-2, with the 6-32 blind nuts on the inside of the fuselage as shown.


Use the 12" length of 1/2" balsa triangle stock provided in your kit to cut two (2) 3-1/4" lengths to fit directly behind the firewall, at each corner where it meets the fuselage sides. Position each piece and press them firmly against the blind nuts to leave an impression. Use a hobby knife to cut shallow half-round reliefs in each piece to clear the nuts. Glue these in place, keeping glue away from the nuts. Use the remaining triangle stock to cut, fit and glue a piece to fit on the top front edge of the landing gear mount, against the bottom rear of F-2, as shown on the plans.


46. Glue the 1/8" ply tank floor in place to the fuselage sides, the back face of F-1 and the front face of F-2. Using the 1/8"x1/4"x36" balsa stock in your kit, cut a 3" length. This piece is now glued into the slots in the doublers, on the bottom of the fuselage, beneath the tank tray.


Insert the remaining 4" length of female receptacle tube into one fuselage side and out the opposite side. Mark the excess tubing with a pencil and remove the tube. Cut the excess material off with a razor saw and reinstall the trimmed tube back in place. Its edges should be flush with the fuselage sides. Holding the tube in place, use a sanding block to lightly sand its outer edges smooth with the fuselage side - do not glue in place yet.


From your kit, locate the .875"x15-1/4" aluminum tube wing joiner and the 3/16" dia. x6" wood dowel. Use sandpaper to smooth each end of the tube, chamfering the ends a little to help it fit into the female receptacle tubes a bit easier. Insert one end of the aluminum tube into the fuselage receptacle tube, sliding it all the way through and roughly centered on the fuselage. Insert the 3/16" dia. dowel into the rear 3/16" dia. hole (located just beneath the servo tray) and center it in the fuselage. Slide a wing panel in place by inserting one end of the aluminum tube into its receptacle, sliding it to the fuselage. The rear dowel inserts into the mating hole in W-1. Press the panel in place to the fuselage.

Repeat the procedure to mount the remaining wing panel. Hook a #64 rubber band to one of the J-hooks and stretch the rubber band three times between each hook to seat the wing panels in place. Check the relationship of the wing panel root ribs to the fuselage sides - they should be flush with no gaps. With the wings still attached, apply glue to the inside female wing tube/fuselage side joints. Also apply glue to the female wing tube, where it meets the front edge of the servo tray.


IMPORTANT: In this step you will install the rear 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 fuselage. Hold the two rear fuselage sides together with the 1/4"x1/2" spacer between them (the 1/4" width simulates the tailpost on the fin) and tape or pin the assembly accurately and securely in place. Glue rear 1/8" ply former F-7 in place. Glue former F-6 in place, followed by F-5.


From the contents of your kit, locate one (1) 1/8" O.D. x30" length of inner nylon tube. This tube will be used for the internal receiver antenna housing/exit. Use a piece of 220 grit sandpaper to scuff up the outer surface of this tube. As shown on the plans, insert one end into the 1/8" hole in the bottom of the servo tray, just ahead of the throttle servo location, leaving about 1/16" exposed on the top of the tray. Glue the tubing in place to the tray. Now bend the tubing back toward the rear of the fuselage and press it into the bottom center slot in former F-4 and glue it in place. Press the tubing in place into formers F-5, F-6, and F-7. Glue the tube in place to F-5 and F-6 but not to F-7 yet. Do not yet trim the excess tubing.


Locate the long fuselage bottom sheet part FB-3 and the shorter 1/8" ply hardpoint doubler from your kit contents. As shown on the plans, the hardpoint doubler is glued in place on top of the FB-3 part, at the very rear, with the 5/16" dia. holes in each part aligned. Glue these parts together now. Cut a 1/4" length off the remaining length of 5/16" dia. center drilled dowel. From your hardware package, locate one (1) 2-56 blind mounting nut. Apply glue to the outer surface of the nut and insert it into one end of the dowel. Press the nut in place firmly and wipe any excess glue. Glue the dowel/blind nut part into the 5/16" dia. hole at the rear of FB-3, with the nut located inside the fuselage. Lightly sand the dowel smooth with the surface of FB-3.


52. Remove the 1/4"x1/2" spacer from the rear of the fuselage. The Fuselage Bottom part FB-3 is now glued in place. First feed the nylon antenna tube through the slot in the rear of the part. Fit FB-3 in place, securing it firmly to the fuselage sides with tape. Use thin CA glue with an applicator extension to glue FB-3 in place, from the inside of the fuselage. Also apply glue to the bottom edges of the F-4 through F-7 formers, where they contact FB-3.


Turn the fuselage upright and from the inside, apply glue to the antenna tube exit. Turn the fuselage over and use a sharp single edge razor blade to trim the excess antenna tube flush with the bottom surface of FB-3. Use a sanding block to sand this antenna exit location smooth. We would suggest using a little light weight filler to fill this area.


The outer elevator and rudder pushrod tubes are now installed. As shown on the plans, these nylon tubes fit through all the formers, from F-4 back through F-7, through the holes provided in each former. Also note that these two pushrod tubes cross each other between F-6 and F-7. As a result, the elevator pushrod, driven by the elevator servo mounted on the left side of the tray, exits the right side of the fuselage, through the upper exit slot. Likewise, the rudder servo is mounted on the right side of the servo tray, with the rudder pushrod exiting the left side of the fuselage through the lower exit slot.

Also note that only about 3/32" of tubing protrudes through the front of F-4. Use 220 grit sandpaper to scuff the outer surface of the pushrod housing tubes. Feed each tube through the appropriate holes in the formers and out the correct upper and lower exit slots at the rear of the fuselage. Glue the tubes in place to each former and exit slot. Trim the excess tubing flush with the fuselage sides at the exit slots with a single edge razor blade. Lightly sand the exits smooth with a sanding block. Use light weight filler to fill any voids at the exit slots.


Glue the Fuselage Top 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 small sanding block.


Glue Fuselage Bottom part FB-2 in place beneath the tank compartment and then glue the forward Fuselage Bottom part FB-1 in place. Use your sanding block to lightly sand the bottom of the fuselage smooth.


The engine throttle cable tube should now be installed. Locate the 1/8" O.D. x18" length of nylon tube from your kit contents. As shown on the plans, drill a 1/8" dia. hole through the F-1 firewall, lined up with your engine s throttle arm. The 1/8" nylon tube passes through the firewall and through the laser cut hole in F-2, where it terminates at the throttle servo location, lined up at the same level as the servo output arm. Later, you will install the throttle cable into this tubing. Before slipping the tube in place, scuff the surface with 220 grit sandpaper, install it and glue in place with thick CA. Trim the excess tubing in front of F-1.


Before closing the tank compartment with the top tank sheet, we suggest that you first make some preparations for installing your fuel tank:


The fuel tank shown on the plans and used in our prototypes is a standard 8 ounce Du-Bro tank. This tank is installed through the top canopy hatch opening, through F-2 and onto the tank floor. The laser cut oblong hole in the F-1 firewall is there to allow two fuel lines to pass through (one line to the carburetor and the other to the pressure nipple on the muffler). This is a simple 2-line system allowing the model to be fueled through the carburetor line with the overflow on the pressure line. Some builders may be tempted to create a removable tank hatch directly over the tank for easy access. In the interest of lightness and structural integrity, we suggest that you do not do this. Realistically, the tank only needs to be inserted once so constant access is not a real issue.


Access to the tank is easy if you use filament strapping tape to create a rear tab that allows you to grasp it and pull the tank out if needed. To do this, use alcohol to first clean the outside of the tank. Then wrap the length of the tank one or two times with strapping tape. Then wrap a third time, folding a 1-1/2" - 2" tab at the rear. The tab gives you a nice grip on the tank in order to easily pull it out.


The tank compartment in this design is large, leaving space between the fuselage sides and the tank when it is in place. Since the tank must be held firmly in place, you need to address this requirement now, while you have access to the compartment. We use a very easy and virtually weightless method to accomplish this task. We first cut two (2) 2"x5" pieces of 1/2" thick open cell foam rubber (the light kind, used for furniture padding, packing material, etc.). We sprayed one side of each of these foam rectangles with 3M 77" Spray Cement and adhered them to each fuselage side, inside the tank compartment. When the fuel tank is installed, simply push the tank into the compartment and it will be firmly held in place between these two foam pads.


With the fuel tank and throttle tube considerations addressed, the laser cut top tank sheet can now be glued in place. This sheet ends at the rear face of F-2 and extends forward over F-1 onto the fuselage sides. Trial fit this sheet in place. Sand its edges to bevel them, allowing them to fit to the fuselage sides, without gaps. Once you are satisfied with the fit, glue the sheet in place, using masking tape to hold it firmly. When the glue has set, sand the rear edge of the sheet smooth with the face of F-2 with a small sanding block.


Locate the 1/8" ply hatch base and the 3/16" sq. x24" balsa hatch rail stock from your kit contents. As shown, the hatch base has two 3/16" sq. locating rails glued to its bottom side, locating it to each fuselage side. Start by cutting two (2) 11-3/16" lengths of 3/16" sq. balsa stock. To position these accurately, fit one piece into the fuselage just behind the forward hatch mount and in front of F-4. Use a scrap piece of 1/16" balsa to 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 in the center) against the back face of F-2. Use accelerator to set the glue. Remove the pins holding the rails in place and remove the hatch base.


Using the lite ply canopy angle guide, glue F-4T in place onto the front edge of FTR (note that the tab on F-4T fits into the slot in the forward edge of FTR). Use a 90 deg. square to glue top formers F-5T and F-6T in place into their respective slots in FTR.


Trial fit the top 1/4" sq. balsa spine in place into F-4T, F-5T, F-6T and F-7. Carefully trim the ends to match the front face of F-4T and the rear face of F-7. Glue the spine in place. Using the 1/8"x1/4"x36" balsa stock provided, cut, fit and glue the four (4) remaining side stringers in place into the same formers. Sand the face of F-4T and F-7 smooth with a small sanding block.


From the parts bag in your kit, locate the 1/8" dia. x1" dowel. Also locate lite ply formers F-4 Cap (without bottom tab) and the matching Canopy Hatch former (with tab). Cut the dowel to a length of 1/2", round one end with sandpaper and set it aside for the moment. Insert the remaining 1/2" length into the hole in F-4 Cap former, to act as a positioning guide. Apply glue to the front face of the F-4T stringer former and glue the F-4 Cap former in place, using the dowel as a locator. Remove the dowel.


Install the hatch base onto the top of the fuselage with a strip of wax paper at its rear edge, protecting the F-4 Cap former from getting glue on it when the Canopy Hatch former is in place. Secure the hatch base to the fuselage with masking tape. Apply glue to the bottom edge of the former and glue it in place to the back edge of the hatch base, engaging its tab into the slot. The former should be in full contact against the face of the F-4 Cap. Insert the scrap 1/8 dia. dowel through the hole in the Canopy Hatch former, F-4 Cap former and F-4T, aligning all three with each other. Use accelerator to set the glue and remove the dowel.


65. Remove the tape and remove the canopy hatch assembly from the fuselage. Apply glue to the unrounded end of the 1/8" dia. dowel prepared earlier and insert it into the back face of the Canopy Hatch former, flush with the front face. Set the glue and sand the front of the former smooth with a small sanding block.

BUILDERS TIP: Before gluing the top hatch sheet in place you may consider adding a little color to the exposed wood hatch floor and rear canopy hatch former, to show through the canopy. The model on the kit box has a zinc chromate color. We did this using light weight colored art paper. This is available in many different colors - gray, flat black, etc. We cut a piece to shape and used 3M 77" Spray Cement. It is an effective look and adds no weight.


Re-install the canopy hatch assembly onto the fuselage with a small strip of wax paper underneath the front edge, folded up to protect the back face of F-2 from glue. Locate and glue in place formers F-2T (located at the front of the hatch base, against F-2) and F-3. Cut and fit the 1/8"x1/4" balsa top stringer in place between these two formers. Cut two (2) 11-3/4" lengths of 3/16"x1/4"x24" balsa, provided in your kit and glue them in place to the left and right sides of the hatch base, on the 3/16" edge. These strips extend from the front edge of the hatch base back to the angled canopy hatch former, aligned with the fuselage sides. Remove the canopy hatch and lightly sand the faces of F-2T and F-3 smooth. Use a larger sanding block to lightly sand the top of the stringer smooth to the contours of F-2T and F-3.


The two laser cut 3/32" balsa canopy hatch sheets are now glued in place. Use a sanding block to chamfer the outer edge of one of these sheets to fit against the 3/16"x1/4" outer hatch edges. Apply glue to the chamfered outer edge and glue in place against the outer hatch edge. Apply glue to the tops of F-2T, F-3 and half of the hatch stringer. Glue the sheet half down to the formers and stringer. Repeat this process on the opposite side of the hatch. It may be necessary to slightly trim the center joint line to achieve a smooth fit. Trial fit the canopy hatch in place onto 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.


Locate the remaining length of 5/16" dia. center drilled dowel. As shown on the plans, this dowel fits into the front of the hatch, flush with the base bottom and flush with the top hatch sheet. A laser cut hole is provided in the base for this dowel but it is now necessary to complete the hole through the hatch stringer and top sheeting. This hole could be made by simply using a 5/16" drill bit. But a much neater way is to sharpen the inside edge of a piece of 5/16" dia. brass or aluminum tubing and use it to complete the required hole. Insert the tubing into the hole in the bottom of the hatch and twist it to cut through the hatch stringer and sheeting. It helps to hold the hatch against a piece of plywood when cutting this hole to minimize or eliminate tearing of the sheeting.
hen the hole is complete, glue the 5/16"dowel in place into the hatch. Sand the bottom of the hatch base smooth where the dowel exits. Turn the hatch over and lightly sand the dowel end smooth with he top sheet. Fit the hatch back in place onto the fuselage. The hole in the dowel should line up with the 4-40 blind nut previously installed in the forward hatch mount. Use the 4-40 x1"nylon bolt in your it to secure the hatch to the fuselage.


Refer to your Key To Laser Cut Parts section to locate the Stab and Fin Filler parts. Also locate the two balsa tapered fin and fuselage fairing blocks. The two fillers will emporarily take the place of the fin and stab to allow exact shaping and sanding of the fairing blocks at the rear of the fuselage. Use a few dots of CA glue to temporarily attach the stab filler to the top of SM (place the CA dots nearer to the fuselage sides). Apply glue along the bottom (only) of the fin filler part and glue it to the top of the stab filler, at 90 deg. upright, aligned directly with the center of the top of the fuselage (as you would align the fin when gluing it in place). Apply a few dots of CA to the bottom and inside edges of a fairing block and tack glue it in place to the stab and fin fillers. Install the opposite fairing block in the same way.


70. Use a razor plane or hobby knife to roughly carve the fairing blocks to match the lines of the fuselage. Use 80 grit sandpaper to further shape the fairing blocks to the cross section shape shown on the plans. When the shape is close, use 220 grit sandpaper to sand the rear stringer area and the fairing blocks smoothly together. Done properly, the whole thing looks almost one-piece.


With the canopy hatch on the fuselage, use a sanding block and 80 grit sandpaper to sand the Canopy Hatch, F-4 Cap and F-4T formers to matching, uniform shape. Be careful here to avoid changing the shapes of these formers. The idea is to maintain their elliptical shapes while matching their outlines. Use a sanding block to lightly sand the 1/4" sq. balsa spine to the profile shown on the plans. Use a sanding block and 220 grit sandpaper to sand the fuselage sides smooth. Doing this automatically sands the two lower side stringers to shape. Finally, use a sheet of 220 grit sandpaper to sand the stringers and filler blocks to their final shape. Be careful to sand this area uniformly.


As shown on the plans, use 3/32" scrap balsa to add fillers between each stringer, at the front and rear. A "Dremel Tool" and drum sanding bit will quickly radius their edges. Lightly sand these fillers smooth to the stringers and to match the front and rear cross sections. The shaped and sanded fin and fuselage blocks are now removed. Use a single edge razor blade to pop loose the stab filler from the top of FSM - the whole assembly should come loose. Use the same blade to now pop loose the two individual balsa filler blocks - set these aside for later use. The stab and fin sanding fixture can be thrown away.


With the exception of mounting the stabilizer, fin and fairing blocks, the basic fuselage is complete and ready for final sanding. Use light weight filler to patch any holes, dings, etc. Use your sanding block and sandpaper to now sand the fuselage smooth. As shown on the plans, we sanded our 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 surfaces in place first, before covering and then cover the fuselage, stab and fin as a single unit. The following instructions assume that you will proceed in this manner.


Locate the 7/8" dia. x15-5/8" aluminum wing joiner tube and the 3/16"x6" hardwood dowel from your kit box. Use a razor saw to trim the dowel to a length of 4-1/4". Lightly sand both ends to radius their edges. Insert the dowel into the rear 3/16" dia. hole, in the side of the fuselage, beneath the canopy area, through the opposite fuselage side. Center the dowel to leave 1/2" exposed on each side of the fuselage - DO NOT glue in place. Insert the aluminum tube wing joiner into the fuselage receptacle, roughly centering it. Take one wing panel and insert the aluminum tube into its female receptacle, sliding it in place all the way to the exposed rear dowel. Insert the dowel into the corresponding hole in the wing root and press the panel in place to the fuselage side. Repeat this procedure with the opposite wing panel.

With the wing panels now in place, check their fit at the roots where they contact the fuselage. They should fit flat to the sides with little, if any, gaps. If the main aluminum wing tube is too long, causing a gap, remove the tube and trim it slightly for a good fit. Place the model on your bench, nose pointed away from you. Place the stabilizer on the fuselage and center it. Use pins to secure the stab in place. Use a measuring tape to measure the distance from the left trailing edge tip of the stab to the left trailing edge tip of the wing. Now make the same measurement on the right side of the model. The two measurements should be the same. If not, adjust the stab accordingly. Once the alignment is correct, use a pencil to mark the location of the fuselage sides onto the bottom of the stab.


75. The stabilizer is now be glued in place to the fuselage (for a little working time, we suggest 5-minute epoxy for this step). Apply a thin layer of glue to the fuselage stab mount (FSM) and also to the leading edge of the stab, where it contacts F-7. Position the stab in place, lining up the lines on its bottom side with the fuselage sides. Pin or use weights to hold it perfectly flat to the fuselage. Now back away a few paces and sight directly at the rear of the model. Is the stab tilting left or right compared to the wing panels? If so, use a little masking tape to hold it in the correct position and allow the glue to cure.


Glue the vertical fin in place to the top of the stab and the back of F-7, with the tailpost glued into the fuselage, between the sides (we suggest 5-minute epoxy for this step). Trial fit the fin in place and trim as required to achieve a perfect fit. Apply a thin layer of glue to the bottom of the fin and its lower leading edge, where it contacts F-7. Also apply glue to the sides and bottom end of the tailpost - not too much. Position the fin in place onto the stab and into the fuselage - wipe off any excess glue with acetone. Visually align the leading edge of the fin with the center of the 1/4" balsa spine/stringer in front of it and pin in place. Use a 90 deg. triangle to position the fin at right angles to the stab and use tape to hold the fin in position. Allow the glue to cure and remove the wing panels from the fuselage.


Before gluing the left and right fin fairing blocks in place, use a single edge razor blade to carefully notch the fin tailpost to clear the elevator joiner wire. This notch should be cut to the trailing edge of the stablizer and 1/4" width. Once satisfied, glue the fin fairing blocks in place to the fin, stab and back of F-7. Use a small sanding block with 220 grit sandpaper to blend the fairing blocks smoothly to the contours of F-7.


Use the 6-32 x3/4" bolts provided to attach 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 from the manifold. Use a pencil and a short straight edge to mark the fuselage side for trimming. Remove your engine and trim away the fuselage side as required. Mount the muffler to the engine and place it back on the mounts to check the clearance.

Some of the later two-stroke engines, with rear mounted remote needle valves, may require a hole in the left fuselage side for clearance. If your engine has this configuration, measure and drill the required hole. When these two issues have been taken care of, lightly sand these areas for covering.


The SOMETHIN EXTRA really lends itself to a wide variety of color schemes. You may even want to cover yours in a scale color scheme as used on one of the many full-size Extra aircraft. Whatever the colors you choose for your model, remember that you will really appreciate a strongly contrasting scheme, in order to keep good visual reference on the model during extreme maneuvers.

To minimize weight and enjoy the full potential of this model, it should be covered in a good quality, light-weight iron-on film, such as SIG Supercoat covering products. If you intend to use two contrasting colors, you will require at least two rolls of covering material - typically one for the base color and the other for the trim color.

NOTE: If you choose to use another brand of covering material, follow the manufacturer s instructions for best results. Different brands of covering have different handling characteristics and application temperatures. However, the basic techniques in applying any brand of iron-on covering film are fairly similar. We would suggest the use of a temperature gauge to set the temperature of your iron to those suggested by the manufacturer (200 deg.F. for SIG Supercoat covering).


Surface Preparation

No matter what brand of covering you decide to use, the surface of your uncovered model directly affects what the covering job will look like when you are done. Poor workmanship will show right through. Now is the time to carefully inspect the surface of the entire model. Carefully sand any mis-matched sheeting joints smooth and use a good quality, light weight filler to take care of any dents, nicks or dings. The entire model should be final sanded with 220 grit sandpaper, progressing to 360 grit. The surfaces to be covered must be clean, dry and dust-free. Use a good quality tack rag and/or compressed air to make sure the model is completely dusted. We would also suggest that you make sure the physical area where you will be covering the model is as clean and dust-free as possible.

BUILDERS TIP: We suggest that you DO NOT seal the inside of the tank compartment before you cover the fuselage. Applying a sealer of any kind (epoxy resin, etc.) to the inside surface of the wood prevents heat from passing through it and can cause bubbling. Even though it is a bit more difficult, seal the tank area after the fuselage is covered.

BUILDERS TIP: The #1 reason for sagging covering, even after shrinking with heat, is internally trapped air. In the case of this particular design, where all of the control surfaces, including the stabilizer and fin are lightened with cut-outs, this can be an annoying problem. The answer is to ventilate each of the lightening hole bays in each part. This is quickly done using a hand-held twist drill with a 1/16" drill bit installed.Simply drill a 1/16" dia. hole through the trailing edge of the stab and fin, into each lightening hole - carefully centering the bit as you go. Starting at the leading edges, do the same thing to the rudder, elevators and both ailerons. When covering these surfaces, start with the bottoms of each. Once the covering is on and wrapped around the leading and trailing edges, use the sharpened end of a piece of 1/16" music wire to poke through each of these now-covered vent holes. Cover the tops of these surfaces and again poke through the drilled vent holes. Now when you use an iron or a heat gun to shrink these covered but ventilated surfaces, the covering will shrink tight and stay that way.

The canopy/hatch (without the canopy in place),rudder, elevators and ailerons should all be covered separately and installed only after the entire model is covered. Once the control surfaces have been covered, the previously cut hinge slots should be located and opened with your hobby knife and a #11 blade.

A two-color trim scheme, such as the model shown on the 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 metal straight edge and a hobby knife with a sharp #11 blade. This technique provides perfectly matched pieces of covering. The rear piece is applied first, followed by the forward piece with an overlap of approximately 3/16". Working in this manner, using the plans as a pattern guide, practically insures a well matched, symmetrical covering job.

Once the model is covered, take a little time to carefully go back over all of your work. Make sure all the seams are attached and adhered and that there is no loose covering. Next, use a sharp #11 blade to open up all of the holes and slots that have been covered; hinge slots, hardpoint holes in the stab, fin and fuselage, hardpoint hole in the canopy hatch, bolt holes in the landing gear block, etc. The two J-hooks can now be screwed in place into the W-1 wing root ribs. Use epoxy to glue the 3/16" dia. x4-1/4" rear wing locating dowel in place into the fuselage and up against the bottom of the servo tray, leaving 1/2" of its length exposed on each side of the fuselage.

BUILDERS TIP: An alternative method to use when opening small round holes beneath covering film, is to briefly heat the tip of a small diameter Phillips screwdriver with a butane torch. Then simply press the tip of the screwdriver to the covering film, directly over the hole. The covering will melt around the edge of the hole, sealing it and leaving a perfectly round opening.

The engine compartment (firewall, fuselage sides and bottom sheeting) must now be sealed. We used SIG Polyester Finishing Resin (SIGFR001) to completely seal the wood in this area. Brush resin just over the edges of the trimmed covering material to seal it as well. Allow the resin to cure and sand it lightly. You can now paint the engine compartment with a complimentary color for your covering scheme or simply use flat black or white SIG Butyrate Dope.

Your kit is supplied with a sheet of SOMETHIN EXTRA logo transfers in both black and white. This allows you to use the white logo against a dark background or the black logo against a light background, depending upon your choice of color schemes. These self-stick transfers are not die-cut so you must cut them from the sheet. We suggest using a sharp #11 blade and a straightedge to do this. Once the transfer is cut out, spray a little glass cleaner onto the area where it is to be applied and carefully lay the transfer in place. The glass cleaner allows you to position the transfer accurately.


Use a soft piece of balsa as a squeegee, pressing the transfer in place, removing any bubbles. Be sure to get all of the liquid out from under the transfer. The two round transfers are the fuel and oil caps and they are positioned in place along the centerline of the fuselage, ahead of the canopy.

Installing Easy Hinges

SIG s famous Easy Hinges have been included with your kit to hinge all the control surfaces. Each ultra-thin hinge is actually a three-part laminate - a tough plastic inner core sandwiched by an absorbent wicking material. They have been chemically treated to slow down the reaction of thin CA glue (normally instant), to allow the glue time to soak all the way to the ends of the hinge and into the surrounding wood. Once the glue has set, the hinge cannot be pulled out of the structure without also tearing the surrounding wood out with it. All surfaces should be covered before hinging.


Begin by inserting six (6) Easy Hinges halfway into the hinge slots in the trailing edge of the stabilizer. Carefully slip each exposed hinge end into its corresponding slot in the elevators (make sure you have the elevators right side up, with the control horn holes on the right side of the fuselage). Snug the elevators up to the stabilizer.


To set the hinge gap, deflect the elevators to the maximum amount of their movement, while firmly holding them to the trailing edge of the stab. For best control response, the gap between the stab and elevators should be as small as possible but big enough to allow full, non-binding movement. Starting at either tip, hold the elevator in this fully flexed position and apply three or four drops of THIN CA glue directly onto the exposed hinge at the center line. The glue will wick into the slot as it penetrates both the wood and the hinge. Go to the opposite stab/elevator tip and repeat the process. Work inward toward the fin and apply glue to the remaining hinges on that side. Turn the assembly over, flex the elevators in the opposite direction and again apply three or four drops of glue to each exposed hinge at the center line. Keep a little CA debonder handy to wipe off any excess glue. The CA will need to cure for 3 to 5 minutes. When it has set, flex the elevators to their full deflection a couple of dozen times to reduce stiffness.


Hinge the ailerons to their wing 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.



Some builders may wish to install a pilot. If so, it should be installed now. We also like this look and chose to install a "Williams Bros." 2-5/8" Sportsman Type pilot bust in our prototypes. This size is correct for the Somethin Extra but is too tall for the available area. We simply trimmed the bust to fit beneath the canopy, glued a lite ply base inside the bust and used epoxy and a sheet metal screw through the bottom of the canopy hatch to hold the pilot securely in place.


Using the disclosure lines molded into the canopy, cut away the excess material using long scissors. Take your time and be as neat as possible. After trimming, use a sanding block to smooth the edges, being careful not to scratch the plastic. Test fit the canopy in place. As shown on the plans, the rear edge fits over the top of the Canopy Hatch former with a little of it protruding back over the F-4 Cap former.


Hold the canopy in place with pieces of masking tape and use a fine tip marker pen to draw a line around its edge, directly onto the covering. Remove the canopy and use a #11 blade and your hobby knife to cut away a 1/16" wide strip of the covering on the hatch, just inside of the line just drawn. Use glue especially made for attaching canopies, such as "RC-56" (DO NOT use CA glue) and glue the canopy in place to the exposed wood in the 1/16" wide strip and to the Canopy Hatch former. Use a damp paper towel to wipe off any excess glue, tape the canopy firmly in place and allow to dry completely. Trim tape can be used to outline the canopy. Adhesive backed covering material, in a color matching the airplane, could also be used for a more one-piece look.


At this point, your rudder should be covered with the hinge slots cut, ready to install.


We used a "Klett" 1" dia. tailwheel on the model shown on the box. There are many small diameter tailwheels available, all with surprisingly different weights. Use one that best fits your weight and balance requirements (see Center Of Balance) section. The wheel can be simply attached using a 1/16" wheel collar. A neater look results from soldering a small washer in place to retain the wheel and then grinding the wire flush with the washer.


b. With the tailwheel in place, the rudder can now be hinged to the vertical fin and fuselage. Follow the directions given in the INSTALLING EASY HINGES section.

Tail Supports

The tail support system used on the Somethin Extra provides an added measure of support and rigidity to the stab and fin. As it does for full scale aerobatic aircraft, this system allows the model to be flown through extremely violent maneuvers without being concerned with the integrity of the tail group. It is easy to make and looks very nice on this particular model. We would urge you to include this support system on your model.


From your kit contents, locate and have ready four (4) 2-56 x10" Control Rods (threaded one end), four (4) Solder Links and four (4) 2-56 clevises. Use the full-size Cross Section at F-7 drawing on the plans for patterns and cut the two top support rods (7-3/4" long, each) and the two bottom support rods (6 long, each).


As shown on the plans, both the solder links and the clevises need to be modified by cutting off the pinned arm of each, leaving only the arms with holes. This is easily done with a "Dremel Tool" and a carbide cut-off wheel.


Starting with the two upper supports, solder a solder link to the top unthreaded ends of each of the two rods. Using the plans as a pattern and a pair of pliers, bend part of the solder links arm to fit flush to the side of the fin, at its hardpoint. Thread a clevis onto the threaded ends of each rod. As shown on the plans, use pliers to bend a part of the clevis arm to sit flush to the top of the stab. Use a 2-56 x3/8" bolt and nut, provided in your kit, to temporarily hold the two rods in place to the fin at the hardpoint - do not tighten yet. Thread the clevises in or out to match the holes in their arms with the holes in the stab hardpoints.

BUILDERS TIP: For 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.


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 the hardpoint at the bottom rear of the fuselage.


When the support arms are made, they can be mounted in place to the fin, stabilizer and fuselage bottom. We suggest using a thread lock product on each of the 2-56 bolts before assembly. Doing this minimizes vibration problems.

Landing Gear And Wheel Pants

The unique landing gear used with the Somethin Extra design looks great when dressed up with the wheel pants provided in your kit. These wheel pants are not difficult to assemble, add a great deal to the overall look of the model and work extremely well on either paved or grass flying fields. Use these steps to produce a very tough, functional and nice looking landing gear set for your model.


With the exception of the wheel pants, ply wheel pant mount, 4-40 x3/8" bolts and the 4-40 blind mounting nuts - install your 2-3/4" dia. main wheels to the aluminum landing gear using the hardware shown in the cross section detail drawing on the plans and supplied in your kit. When properly mounted, the wheels will turn freely but will not have excessive side play on the axles.


Locate the left and right sides of each wheel pant. Apply thick CA glue to the edge of one pant half and glue it to its mate. Do this carefully, matching the sides as closely as possible. Hold the parts firmly together and spray accelerator on the joint. Use your "Dremel Tool" and a drum sander to carefully clear out the molded-in wheel clearance area at the bottom - do not take out too much, it is better to sneak up on this opening. As you clear these openings, periodically check the fit by placing the pant over the tire.


c. To fit the pant over the wheel and against the aluminum landing gear, it is necessary to cut a vertical slot into the lower inside face of the wheel pant, at the location of the axle. The slot allows the pant to fit over the wheel, down onto the 6-32 hex nut which is against the outside face of the aluminum landing gear. This slot needs to be the same width as the hex nut (5/16" wide) and approximately 3/4" depth. It is easiest to use a pencil and a small straight edge to first draw the slot onto the wheel pant. Use a sharp #11 blade in a hobby knife to carefully cut this slot. To fit the hex of the nut at the top of the slot, cut a peak at the top, allowing the hex nut to nest in place. Continue trial fitting in place until 1) the wheel clearance cut out in the pant bottom clears the wheel and 2) the slot fits nicely over the hex nut and against the aluminum landing gear.


Attach the aluminum landing gear to the fuselage, using the three (3) 6-32 x1/2" round head bolts supplied. Place the fuselage on your work bench with the tail wheel in place on its strut. Fit the wheel pants in place, visually lining them up with the fuselage - level, as shown on the plans. From the back side of the aluminum landing gear, use a pencil to mark the two required mounting holes - just above the axle - onto the wheel pant. Remove the pant from the landing gear.


Accurately drill two 7/64" dia. holes through the pant, at the marks just made. Locate the two (2) ply wheel pant mounting plates, four (4) 4-40 x3/8" round head bolts and four (4) 4-40 blind mounting nuts from your kit contents. As shown on the plans, one of these plates is used inside each pant as a doubler. The mounting plates need to be prepared for installation by first using a sanding block to slightly bevel their lower, inside surface to conform to the inside of the wheel pant - see cross-section on the plans. Do this now. Apply thick CA glue to the outer surface of the 4-40 blind nuts and insert them into the two holes in each mounting plate. Use a hammer to tap them into the mounting plate.


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.


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 the slot sides in the pant. Trial fit the wheel pants in place, using the 4-40 x3/8" bolts to mount them to the landing gear. The pants should mount easily, be aligned with each other and be easily removable.


Remove the wheel pants from the landing gear and prepare them for finishing. Use a sanding block and coarse sandpaper to smooth the joint seams. If filler is necessary for any reason, try 5 or 15-minute epoxy glue and micro balloons. Sand the pants completely with 220 grit sandpaper and apply a good primer, such as "K&B". Use 400 wet or dry sandpaper (wet) to sand the pants smooth and ready for paint. You can use almost any kind of fuel proof paint to finish the pants. We have used and can recommend paints such as SIG Supercoat dope and "K&B" epoxy.


The finished wheel pants can now be mounted to the landing gear with the 4-40 x3/8" bolts. We suggest using a thread locking material to eliminate vibration problems (such as "Loctite" Removable Threadlocker 242, Red).

BUILDERS TIP: As shown on the model on the box, the aluminum landing gear has been polished. This is a nice look that can be done to your landing gear. Start by sanding all of the gear s edges smooth with crocus paper. Now you can simply use a good quality aluminum polish such as "Simichrome" or "Flitz" and elbow grease to polish the gear. Another method is to use a bench grinder with a buffing wheel. Use a buffing compound to very quickly polish the gear to a super, chrome-like finish.


Locate the nylon control horns for the ailerons, rudder and elevator and the eight (8) #2 x1/2" pan head screws used to attach them. The two smaller control horns (one left and one right) are for the ailerons - mount these in place with the pan head screws. The rudder and elevator control horns are both larger. Mount these in place with the remaining pan head screws.


Engine And Tank Installation


With the tank compartment and fuel tank already prepared for installation (FUSELAGE CONSTRUCTION, Step 58a,b), the tank is now installed. Use a single 20" length of medium fuel tubing, folded in half. Insert the two 10" loose ends through the oblong hole in the front of the firewall and retrieve them through the tank compartment at F-2. Attach each fuel line to the fuel tank tubes. Insert the tank through F-2 and into the tank compartment while taking up the slack in the fuel lines as you progress. When the tank is in its final position, identify each fuel line (fuel, pressure) and cut the two lines apart. Leave these lines long until they are finally attached to the engine and muffler.


The 6-32 x3/4" round head bolts in your hardware package are used to attach the motor mount arms to the firewall. We suggest using a thread lock product, such as "Loctite" Removable Threadlocker 242 (Red) to eliminate vibration problems.


Use the appropriate 6-32 hardware (not supplied) to mount your engine - without the muffler - to the motor mount arms. We suggest using four (4) 6-32 x1" cap head bolts with 6-32 lock nuts to mount your engine.

With the tank and engine now in place, the throttle connections can be made to the engine and throttle servo in the following section of this manual. Once the throttle is connected to its servo and final adjustments made, the muffler, fuel lines, prop, and spinner can all be attached.

Radio Installation

If you have followed these instructions to this point, installation of the radio system becomes a simple matter of dropping the servos in place, securing them with the screws supplied with your system and then making the connections to each of the controls. If you are using one of the new generation of highly simplified computer radios - such as the Airtronics Radiant, Futaba 6XA, etc. - the radio installation becomes even easier with features such as total travel control, sub-trims, etc.

The receiver is mounted on top of the ply radio tray, just forward of the antenna tube exit hole. This places the receiver in the perfect position to accept the left and right aileron servo leads. We wrap our receivers in 1/4" foam, held with rubber bands. It is then secured to the radio tray with a single 10" 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 shown on the plans, the switch can be mounted to the side of the fuselage, below the forward wing panel location. For a more professional look, you could mount the switch internally, on the floor of the fuselage, just behind the landing gear mounting block, activated with a length of music wire exiting the fuselage side - this is how we did it with our models.

Locating your battery pack in this design is very easy. Looking at the fuselage plan you can see that if you are using a typical 450 - 600 mAH battery pack in a flat configuration, it can be installed anywhere from directly beneath radio/servo tray, forward to the firewall, beneath the fuel tank. That is a lot of distance! Given that much latitude in locating the heaviest component of your radio system, achieving the correct Center of Balance should not represent a problem. Be sure to read the CENTER OF BALANCE section of this manual for more information.

When mounting the aileron servos into their bays in the bottom of the wing panels, you will likely find that you will need to add short (about 6 ) servo lead extensions to get the length needed to reach the receiver. If this is the case, be sure to secure the plugs with either tape or some other mechanical method to ensure they will stay plugged together. We also found that when installing our aileron servos, using hemostats to get the servo leads started into the wing tubes was helpful. Always use the rubber servo grommets and eyelets that all radio manufacturers supply with their systems.

Pushrod Assembly


Begin with the rudder and elevator pushrods - the instructions are the same for both. Locate the two 30" lengths of 1/8" O.D. nylon tubing, four (4) 10", threaded one-end metal pushrods, two (2) nylon R/C links and two (2) solder links. Cut 6-1/2" off the unthreaded ends of two 10" pushrods, leaving a length of 3-1/2" each. Smooth the cut ends and insert the unthreaded end of one of these into the end of a 30" nylon tube, right up to the threads. Grip the threaded end with padded pliers and thread it into the nylon pushrod about 3/16-1/4".


Thread one of the nylon R/C links onto the remaining threads, roughly centering it on the threads for later adjustments. This prepared end will be located at the control surface (rudder or elevator).


Prepare the two remaining 10" metal pushrods by cutting 8-3/4" off the unthreaded ends, leaving a length of 1-1/4" with threads on one end. As shown on the plans, solder a solder link onto the unthreaded end of the metal pushrod.


Insert the unprepared end of the nylon pushrod into the rear pushrod exit tube at the rear of the fuselage, all the way through the tube, into the radio compartment. Connect the nylon R/C link to the control horn on the rudder or elevator and neutralize the surface with tape or a fixture. Attach the solder link to the centered servo output arm. Mark the nylon pushrod for cutting at a point where it will accept about 3/8-1/2" of the metal pushrod threads. Remove the nylon pushrod from the fuselage and cut it to length at the mark just made. Thread the solder link and pushrod into the end of the nylon pushrod and remove the nylon R/C link at the other end - not the metal pushrod.


Re-install the nylon pushrod, this time through the tube in the radio compartment. Connect the solder link to the centered servo output arm. Thread the nylon R/C link back in place at the rear of the fuselage. Neutralize the control surface and attach the R/C link to the control horn.


Aileron pushrods are next. Thread a nylon R/C link in place on a 10" metal pushrod, centering it on the threads for later adjustment. Attach the R/C link to the aileron control horn with the unthreaded end facing forward, toward the aileron servo. With the servo output arm centered, attach a solder link in place to the arm. Mark the metal pushrod for cutting, at a point where it will pass through the solder link. Remove the pushrod and cut it to length. Solder the link in place and reconnect the completed pushrod to the aileron servo and nylon control horn.


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 cable into the throttle housing tube and push it into the radio compartment. Turn your radio on and set the throttle stick to low throttle, with the trim lever centered. Push or pull the throttle cable to close the carburetor on your engine. Connect the solder link to the throttle servo output arm. Mark a cutting point on the cable that will allow it to be attached to the solder link. Remove the cable and cut it at the mark just made. Slide the trimmed cable back in place into the radio compartment and solder the link in place to the end of the cable. Connect the solder link to the throttle servo output arm and the nylon R/C link to the carburetor throttle lever. Use your radio to test the throttle action and adjust as required at the carburetor, using the nylon R/C link.

Set all flight surfaces to neutral. In the case of the ailerons, this would normally be a difficult job because of the thickness of the wing panels and the inability to sight down the trailing edge of each to see their relationship. However, we have included a laser cut Aileron Position Guide (APG) in your kit, which allows independent neutral positioning for each aileron.
The APG is simply held against the fuselage side, on top of the wing panel at the trailing edge. The aileron pushrod is adjusted to align the aileron parallel with the flat, at the rear of the APG part - simple and easy.

After the flight surfaces have been neutralized, take the time to fit each clevise with a short length of fuel tubing (medium is fine for 2-26 hardware) to keep the clevises firmly in place to each control horn and servo arm. This common safety practice has saved a lot of models in the past.


There are any number of different radio systems currently in use and on the market. Because of this, it is not possible to explain the optimum set-up of all these systems for this particular model. The following suggested control surface travel information is based upon our experience with the Somethin Extra. These suggested surface movements should be considered as a starting point. As your experience and confidence builds, these control movements can be increased to outrageous amounts, to really explore the model s (and your) capabilities!

Control Surface Travel Chart
SurfaceLow Rate TravelHigh Rate Travel
ELEVATOR1-1/4 up - 1-1/4 down2 up - 2 down
AILERONS1 up - 1 down2 up - 2 down
RUDDER1-7/8 left-1-7/8 right2-1/4 left- 2-1/4 right
THROTTLEfull range of travel

NOTE: These measurements were taken as follows:
  • Aileron travel measured at the inboard trailing edge.
  • Elevator travel measured at the widest inboard trailing edge.
  • Rudder travel measured at the widest lower trailing edge.

If your are using a computer radio, the following information may be of help to you. Listed and explained below are types of control surface mixing that would be desirable on this type of model and the effect they have on the flight performance of the SOMETHIN EXTRA

Control Surface Mixing
MixingControl SurfacesEffect
FLAPERONSAILERONS Using virtually any of today s modern computer radios and two separate aileron servos, it is possible to use the ailerons as flaps. In actual flight, lowering both ailerons as flaps typically causes the model to pitch down, requiring some corrective up elevator input to maintain level flight. Some transmitters have a rotary Flap knob, allowing the flyer to select the best flap position for any given wind conditions. With each aileron servo plugged into a separate channel in the receiver, lowering both ailerons as flaps still allows 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-FLAPELEVATORS 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 programmed rate. Likewise, deploying the flaps upwards causes the elevators to travel downwards at a programmed rate. This mixing feature can be used to give your SOMETHIN EXTRA the ability to perform incredibly sharp turns and super tight loops.
PRE-SET SWITCH FLAPS and ELEVATORS As mentioned in Note #1, some radios have rotary knobs for a flap channel and some have 3-position switches allowing pre-set flap and elevator positions and some systems have both these features. The 3-position switch typically allows for three different flap positions. For example: Switch setting #1: Raise the flaps 10 deg. or so, causing the flaps to act as spoilers on a sailplane, spoiling some of the wing s lift. This will cause the SOMETHIN EXTRA to make faster descents for those quick take-offs and landings sometimes required in fun fly contests. Switch setting #2: With the switch in this position, the flaps are held in the neutral position, with the exception of the elevator to flap mixing for normal flying. Switch setting #3: Lowers the flaps to about 30 deg. This allows the model to make extremely slow landings or to even hover or appear to fly backwards in certain wind conditions.

Double check your entire radio installation and remedy any problems now. Make sure that all five servos have their output arm screws back in place and tightened. We also suggest that you periodically check the available voltage in your receiver and transmitter packs with a good ESV to avoid battery related problems. Last, no matter how good you may think your radio system is, make it a routine part of your pre-flight procedures to always perform a thorough range check before every flying session.


Center Of Balance

Like all R/C models, the Somethin Extra was designed to be flown with the proper Center of Balance (or CG). As shown on the plans, the CG falls exactly in the center of the 1/4" wing spar, or 3-1/2" back from the leading edge. As previously mentioned, this design allows for a relatively huge shift in the location of the airborne battery pack. However, if for some reason you find that your model is still either nose heavy or tail heavy, consider some of the following suggestions before resorting to non-functional lead weight.
  • Wheels: There are 2-3/4 dia. wheels suitable for this design that are extremely light (such as the Dave Brown Treaded Lite Wheels) and heavier wheels from other manufacturers. This is a great way to adjust and help correct an out-of-balance model.
  • Tailwheels: A simple way to help control balance is to consider ultra-light plastic tailwheels to cure a tail heavy condition or much heavier tailwheels to help with a nose heavy situation.
  • Spinners: Like the wheels, there are very light 2-1/4" dia. plastic spinners and considerably heavier metal spinners of the same diameter - yet another way to control the CG.
  • Propellers: Some of the more popular composite plastic props can be fairly heavy in contrast to the considerably lighter wood propellers with the same diameter and pitch. This is another good place to control the balance of your model.
  • Heavy Hubs: Need a little more weight in the nose? Consider using one of the many Heavy Hub propeller hub products sold by Harry Higley & Sons, Inc.
  • Battery Packs: If your smaller 500 mAH pack is not helping much in getting the model to balance, consider moving up to a larger, somewhat heavier pack. Functional weight is the best kind!

In the unlikely event that your model is still out of balance, then you will probably have to resort to the use of lead weight. If so, we caution you to make very certain that the weights are securely attached to your model. The Somethin Extra is capable of extreme high-G maneuvers that could possibly dislodge improperly attached lead weights.

Last, we also suggest that you balance your model laterally. To do this, use light line or string to suspend the assembled model inverted, from a front center and rear center point on the fuselage - typically from the engine s prop shaft in the front and the tailwheel wire at the rear. Properly balanced laterally, the wings would remain level. If the airplane is heavier on one side than the other, the wing on the heavy side will 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 model always performs better and is well worth the effort.


The SOMETHIN EXTRA is most certainly not a beginner's model. It was designed as an all-out aerobatic aircraft with all of the inherent attributes of those types of airplanes. If this is your first aerobatic model and you have relatively little actual air time, we would urge you to seek the assistance of a qualified R/C pilot to help you through the first few test flights.

Keep the ailerons and elevators in their low rates. Once airborne, get to a reasonable altitude before inputting any trim changes. Once the model is trimmed for straight and level flight, begin getting the feel for the way it flies. At an altitude of about three mistakes, you can begin exploring its ability to loop, roll, etc. When you are more comfortable (typically within minutes), go to high rates and begin to enjoy this model as it was meant to be enjoyed! This thing will perform maneuvers that are not yet even named! Explore the model s ability to spin - upright and inverted and while you are at it, check out the stall speed while still at altitude. When you are more familiar with the SOMETHIN EXTRA, start playing with the flaperons. You will not believe what you can get this model to do!

FLYERS TIP: We suggest that you do not lower the flaperons above 1/2 throttle. At higher speeds, lowering the flaps may cause sudden pitch changes that may be difficult to correct at low altitudes.

One word of caution is appropriate here. This design has a tendency to make you feel so confident that you may begin to fly it too close to you and/or the ground. The airplane has the ability to recover from virtually any maneuver instantly but a point could be reached where you may run out of altitude and ideas all at once. You also need to get yourself comfortable with the shape and color of your model during some of the wilder maneuvers. Knowing which side is up and the direction of flight is always a good thing. If your engine quits for any reason, be aware that the SOMETHIN EXTRA flies very well dead-stick. However, the thickness of its wing does not allow it to penetrate very well in high wind, dead-stick conditions. If the engine quits and you have some distance to travel back to your field, keep the nose down, the speed up and avoid turns.


Landing this design is super easy. The first few times, without flaps, keep a little power on the engine to keep the model moving. It can be flown right down to the ground, landing on the mains with a very short roll-out. With a little experience and using flaps, you can consistently land this model in exactly the same place every time.

Last, this design places a real premium on a great running engine. If you are consistently having engine problems, take the thing out of the model and either fix it on the bench or replace it with a good engine. This is not an airplane that is going to make a bad engine look good. Nuff said.

Flying machines of any form, either model-size or full-size, are not toys! Because of the speeds that airplanes must achieve in order to fly, they are capable of causing serious bodily harm and property damage if they crash. IT IS YOUR RESPONSIBILITY AND YOURS ALONE to assemble this model airplane correctly according to the plans and instructions, to ground test the finished model before each flight to make sure it is completely airworthy, and to always fly your model in a safe location and in a safe manner. The first test flights should only be made by an experienced R/C flyer, familiar with high performance R/C aircraft.

The governing body for radio-control model airplanes in the United 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 someone else. For more information, contact:
5151 East Memorial Drive
Muncie, IN 47302
Telephone: (317) 287-1256

Customer Service

SIG MFG. CO. is totally committed to your success in both building and flying the SOMETHIN EXTRA 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.

401-7 South Front Street
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

© Copyright SIG Mfg. Co., Inc.

SIG MFG. CO., INC............Montezuma, Iowa 50171-0520

The craftsmanship, attention to detail and actions of the builder/flyer of this model airplane kit will ultimately determine the airworthiness, flight performance and safety of the finished model. SIG MFG. CO's obligation shall be to replace those parts of the kit proven to be defective or missing. The user shall determine the suitability of the product for his or her intended use and shall assume all risk and liability in connection therewith.