BUILDING THE HURRIKANE
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| Tools needed: |
Clamps |
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Wood glue (yellow) |
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Wood glue (polyurethane) |
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Sanding block |
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X-Acto knife |
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Drill |
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Tap drill and tap for mounting the wing |
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Ruler |
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Slotting tool for 1/64th ply. |
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Razor plane |
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Incidence meter |
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Spirit Level |
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Zona saw |
| Components needed: |
Wire and connectors for internal linkage |
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Hinges |
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Glass cloth (optional) |
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Epoxy |
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Milled fibers or Chopped Carbon |
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Thin CA |
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4-40 screws and blind nuts for the landing gear |
BUILDING THE FUSELAGE
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This picture shows the parts that are needed to start assembly. Note there is a right and left side to the fuselage. The right side has the fuel tubing exit holes. Install the 1/64th ply doublers. For this I used carpenters (yellow) wood glue thin slightly with water. Apply glue to one side using an acid brush and attach it to the fuselage. Be sure to line up the notches for the formers. |
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Install both rear doublers using the same thinned wood glue method. Once you have glued the doublers in place and they are lined up. Place one side across a flat surface. Then apply piece of wax paper on top of the side against the flat surface. Stack the second side on top of the first. Be careful that the doublers do not shift during this process. Lastly, apply some weight to the two sides to keep them flat while the glue is drying. I used old college text books. |
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Install the front former as shown using urethane wood glue (a common brand is "Gorilla Glue" this is the type of glue that foams during the drying process). I don't worry about the burnt edges, simply wipe the edges (both surfaces) with a damp rag before applying glue. Note the hole in the bottom left corner of the former is for the throttle cable. |
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Install the rear wing bolt block, the rear former and the servo tray to the same side as the previously installed front former. Use the same urethane glue with a damp rag. Note the orientation of the rear former and servo tray. The next picture is clearer for the servo tray. |
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Wipe the edges of the parts to be glued and install the second side of the fuselage using urethane glue. Clamp the parts together to prevent movement during drying. Note the orientation of the servo tray and former. |
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This picture indentifies the location of the throttle guide tube hole and the installation of the front wing hold down block. (You are looking from the nose to the tail, from the top) |
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Install the landing gear plate and the first of the 3 part firewall. |
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Install the rear horizontal support and rear former using the same urethane glue. |
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This picture shows how the rear of the fuselage should look if properly installed. |
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Note: the shape of the fuselage is slightly concave aft of the wing. |
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Install the 1/4" firewall and the front 1/8" plate. Note: the front plate must be aligned so that the top and bottom decking will fit. |
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Install the bottom decking using the same urethane glue. Note: the bottom decking is the longer of the two 1/8" light ply parts. |
INSTALLING THE MOTOR MOUNT
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Align your motor mount and drill through the firewall to accept the 4 mounting screws. Then redrill the holes to accept the blind nuts. Note: I use only DuBro 6-32 blind nuts these are the best quality and they are the smallest in diameter. |
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This picture shows how close the blind nuts are to the fuselage. And now the fuselage is ready to receive epoxy fillets in the corners to add strength. I have used many different combinations. The messiest is chopped carbon. The neatest is milled glass or cotton flocks. |
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Here you can see what looks like fur balls but is actually, chopped carbon and epoxy in the corners. |
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Next I install 1/4" triangle stock to the bottom of the front and rear wing mounts and to the top of the landing gear block. Note: before putting the top decking on make sure you tank fits. |
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This is how the triangle stock is installed onto the rear wing mount. |
MAKING A 1/64TH PLY INSERT TOOL
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The picture to the left shows 4 pcs of 1/8 ply that will stacked together to make a tool that can be used for putting a slot into the edges of the stabilizer. |
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Stack all the pieces together to sand the edges square. |
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Drill two 4-40 body holes approximately 1.25" apart in the center of the group |
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Lay one of the widest parts down first then a narrow piece. This pictures shows the approximate angle of the #11 blade that will be sandwiched inbetween the different layers of 1/8" |
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This is how the tool will appear when complete. The knife blade is sandwiched between the two narrow pieces of 1/8" ply and the wider pieces provide a fence for sliding the tool along the stab. NOTE: because the 1/8" ply may be slightly smaller you may need to apply 2 layers of tape to make the gap between the fences larger. |
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Here is a second picture of the tool. |
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Draw an arrow on the part to show the direction in which the part must be passed through the tool. |
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Lastly this is how to install a slot along the edges of all of the stabilizer components. |
BUILDING THE STABILIZER
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Glue the tips in place and tack glue the two stab halves together. Also, tack glue the elevators to the stabilizer. I have seperated these items because the cut lines give you perfect frames of reference. I glue these parts back together to make it easier to sand the airfoil. The elevators will be cut away later as well as two halves cut along the center line. |
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Slot all the edges of the stabilizer to accept the 1/64th ply inserts. I have shown previously in these instructions how to make a slotting tool. I personally use a Dremel saw blade in a drill press with a guide fence. This method provides a slightly wider slot then the #11 blade mentioned earlier. Finally, install all the ply into the edges of the stabilizer. Once installed flood the edges with thin CA to keep the ply in place. |
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The lines indicate that material will be removed in those areas. For this I use a razor plane first, and then finish it off with a sanding block. Normally, I use 80 grit to start and work my way down to 220. |
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This is a picture of the razor plane and the angle I normally cut at. |
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Lastly, this is the angle at which I sand the part to keep the shape consistant. Note: pay close attention to not sanding or planing too far so that the 1/64th ply is exposed. |
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I normally glass my stabilizers but this is not a necessary step for 424 unless the builder wishes to. I use 3/4 oz cloth and epoxy. I keep all of the pieces together until glassing and sanding is complete. Dave Norman has published a article on the NMPRA site that explains how to do skinned hinges. I am not using this method here so that you can see the different options. |
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To trim the excess cloth I use a small sanding block at an angle to the edges. |
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Once you have completed the sanding and filling of the cloth. Mark the top of each elevator and stab half. Also mark the location of the hinges. |
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Using a Zona saw cut the end of the elevator free from the tip of the stab. |
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To cut along the hinge line I use a straight edge and a X-Acto knife. |
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Using a round file make the hinge line slightly concave along the length of the stabilizer. |
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Using a sanding block bevel the leading edges of the elevators. NOTE: this does not need to be extreme as this is not a sport plane. Approximately 1/16" is adequate. Next slot all of the surfaces to accept your hinges and test fit your parts |
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This is what the stab will look like when the hinges are complete. Note: the size of the gap between the elevators and the stab. |
BUILDING THE V-TAIL ASSEMBLY
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Using a Zona saw cut the stabilizer in half. |
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Tack glue the traingles to the bottom of each of the stabilizers as shown. These are used as a crutch during the assembly process |
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At this point I use the edge of my building table to sand in the angle required for forming the V-Tail. Keep your sanding block square to the top of your bench and the proper angle will be achieved. Note: The longest side of the triangle is attached to the bottom surface of the stab, and the second longest side is sitting on the table. Therefore the shortest side provides the height. |
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Repeat the sanding process for the second half. Once completed this how the stabilizers should fit together. |
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Here is a second picture of the how the crutch system works. Place some wax paper on your table and CA the two halves together. Leave the crutches in place until the assembly has completely dried. Lastly, remove the crutches and your stab angle is complete. |
MAKING THE INTERNAL ELEVATOR LINKAGES (piano wire/clevis)
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The purpose of this picture is to show how to use the 1/4" triangles as templates for bending the elevator linkage. |
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There are few different ways to make this linkage. I will explain two different ways. The first is using 3/32 piano wire and the second is using Du-Bro 4-40 pushrod material. First make a 90 degree bend at the end of your wire as shown. Next place a mark 1.25" from the first bend. Note: The leg point up is the part that will be installed into the elevator. |
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This picture shows a completely bent right side linkage. The leg extending into the bottom right corner of the picture is approximately .75" long. |
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Complete the same process for the left side linkage. Make sure to used the traingles as templates for the proper angle. |
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Cut two pieces of 1/8" brass tubing (the tubing supplied with Sullivan fuel tanks works well) approximately .75" long |
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Using a pair of needle nose pliers pinch the last .25" of the brass tubing. |
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This pictures shows the end of the tubing being pinched. Repeat the same process for the second piece of tubing. |
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Sand the end of the piano wire along the length that will receive the brass. This cleans the metal prior to soldering. Slide the brass parts into place. Next solder the brass to the piano wire. I use Sta-Bright solder for this process. NOTE: pay attention to the angle of the crimped ends. They must be orientated as shown. |
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The last step is to drill a .0625" hole in each brass tube to accept your clevis. |
MAKING THE INTERNAL ELEVATOR LINKAGES (4-40 rod/ball link)
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Mark the 4-40 rod 1.5" from the threaded end. This will be the first bend. Next cut the threads off so that the rod is 13/16" long fron the mark to the end of the threads. This provides the proper length of threads (approximately, 1/8") for the Du-Bro threaded ball link. |
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This picture shows the length of the rod that will project down into the fuselage and ultimately be connected to the servo via a ball link. Next thread the Du-Bro threaded ball link onto the end of the rod and USE loctite to keep it in place. |
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Bend the wire as described above. To complete the assy, sand a taper into the legs of the linkage that will extend into the elevator. |
INSTALLING THE LINKAGE INTO THE TAIL FEATHERS
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With the elevator hinges in place, position one linkage and mark the elevator to except the wire. |
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Drill into the elevator using a 3/32" drill bit. Keep your thumb and fore finger over the elevator to feel the drill bit getting too close to the outer surfaces. Try not to break through the surface of the elevator. |
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Next use an X-Acto knife to make a small "V" groove from the hole to the end. Then use an extra piece of the threaded 4-40 rod as a file, to open the slot to except the wire. |
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This is what the linkage looks like when installed into the elevator. NOTE: because it is difficult to know the exact position of the linkage you may have to make the hole oblong to allow the linkage to move in and out to obtain the proper spacing inside the fuselage. |
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Mark and install the second side using the same process as described above. Note: your hole will be further out towards the tip and not exactly where the mark is due to the angle. |
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Install the second side and check the fit. The linkage should be situated in such a way that they cannot touch during their motion. Next glue the linkage into each elevator half. I use 15 minute epoxy for this process. The reason for gluing them into the elevator now is that you can see if you have obtained the proper spacing prior to installing the tail. The epoxy should hold the tapered leg into the elevator and the straight leg that extends out the end of the elevator. |
INSTALLING THE TAIL AND CONNECTING THE PUSHRODS
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Using a sanding block sand each side of the fuselage from mid stab to the tail to obtain the proper taper at the tail. NOTE: the thickness of the fuselage sides as you move from the trailing edge of the stab to the rear most point of the fuselage. Use a small diameter sanding drum on a dremel to relieve the area where the linkage enters the fuselage at the rear of the stab. You may have to remove some of the 1/64th doubler. |
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Next use the same small diameter sanding drum to remove the material as shown. This provides the clearance needed to allow the linkage to operate freely. If the material is not removed you may have an issue with the linkage binding. |
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The drawing to the left shows the length of the pushrod for the tailfeathers. |
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The reason the length of the wire is 3.5" on the threaded end is to provide the proper clearance so that the pushrod does not touch the fuselage sides, when connected to the servos. |
INSTALLING THE WING
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If using a composite wing with scribe marks follow the marks, but make sure they will fit the width of your fuselage. I will describe the process I use, if you have a different method please use it. |
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Using the proper tap drill bit start one of the rear holes. I use 10-24 for the rear and 1/4-20 for the front. |
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Next I use my handy, keep your drill bit square tool, to finish the hole. This tool allows the hole to be square to the top surface. Once finished tap the hole and use thin CA to fill the threads and re-tap the hole. Install a screw to hold the wing in place during the drilling and tapping of the front screw holes |
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Next repeat the above process for one of the front holes (opposite the rear tapped hole). Drill, tap, fill with CA, re-tap and install screw. |
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With one front and one rear bolt installed, drill and tap the other two holes. Countersink all the holes and the wing is mounted. |
SETTING THE V-TAIL INCIDENCE
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Mount the wing to the fuselage and set the wing to zero using an incidence meter. A second spirit level is used to make sure the wing is parrallel to the table top. Measure your table to ensure that it to is level. |
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Keep this level in place during the measuring process. The meters check for zero incidence relative to the thrust line and the spirit level checks that the wing is level to the table top. IF the wing is not level to the table the V-Tail will be higher on one side. |
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Using a ruler measure from the corner of the tip at the elevator/stab joint, to the top of the table (this is why it is important that your table be level). On the plans this is dimension "A". |
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Measure at the same point on the other side. Once these two numbers are the same tack glue the rear of the stab in place. This task ensures that the tail is square to the wing. (Not shown, but needs to be done, measure from the tip of each stab to the centerline of the fuselage to ensure the hinge line is square to the wing.) |
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With the trailing edge tacked in place with CA, you will now set the incidence. Measure from the joint between the tip and the stab to the top of the table. This should be the same as the dimension from the rear to the top of the table (dimension "A" on the plans). IF these do not match adjust the leading edge up or down until the two numbers are the same. |
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Check the other side to ensure that the stab hasn't moved. Once you feel the incidence is right tack the leading edge in place. Check all of your meters and levels and remeasure the tail. IF all is correct the 4 corners of the tail should be the same dimension to the table top. (Shown on the plans as dimension "A") IF satisfied, CA the tail in place. Before final gluing make sure your pushrods are in the proper position. |
FINAL FUSELAGE ASSEMBLY
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Install the elevator/rudder servos and connect the pushrods using Z-Bends. Once you are satisfied with the operation of the tailfeathers, glue your hinges in place. |
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Drill an exit hole in the side of the fuselage for the ANTENNA exit tube and secure in place. |
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Install the tube through the rear former and secure in place. |
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Bend the 3/32" piano wire tail skid as shown. Drill a 1/8" hole into the bottom decking in the approximate location shown. |
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Epoxy the tail skid and rear decking in place. |
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Install the bottom decking using the same urethane glue. Note: The grain of this component is running lengthwise to cut down on the number of parts. This cuts down on part count but cause splitting issues later during handeling. IF you choose to substitute cross grain decking for this step now would be the time to do it. |
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Install the front top decking. Note: sand a small taper on the bottom of this part to accommodate the airfoil at the leading edge of the wing. Use the drawing for reference. |
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Install the servo access cover (light ply) and rear top decking (cross grain balsa). At this point it is easier to line all the components up with the wing installed. |
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Install the top rear balsa sheeting. Note: I cut this part free from the front because it was easier to bevel the edges that butt up against the ends of the elevators. |
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Install the sheeting on top of the stab. Note: The edges of this component will need to be beveled to match the angle of the V-Tail and the shape of the airfoil. |
POTTING THE WING
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Cover the wing with masking tape to protect it from getting epoxy where you don't want it. And apply several layers of wax. After waxing cut the bolt holes for mounting the wing. NOTE: MAKE SURE TO WAX YOUR BOLTS TOO. |
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Apply your epoxy and microballoon mixture to the saddle area. |
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Install the wing double checking the incidence. After the epoxy has cured sand the fuselage square to the sides so that no fillet is present. |
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