WARNING

  You can hurt yourself, building this kit! Please use caution and follow proper safety procedures when using the tools and the adhesives needed to assemble this kit.

Powered models are dangerous! All model airplanes present a certain amount of danger to the operator and anyone in the vicinity. Please be careful when starting the motors and use good safety practices when operating this model. Wear eye protection.

We at JK Aerotech, have no control over how this product is used. You, as the operator of this equipment assume full responsibility during the building and flying of this model to operate it in a safe manner. Do not start the engine with anyone, including yourself, in line with a spinning prop or directly in front of a running motor (I have seen props come off). Always keep hands and fingers and other body parts out of the spinning prop. Do not fly over people, or in populated areas. BE CAREFUL!

  By building and flying this model you have agreed to take full responsibility for any property damage and/or personal injury or death caused by this model.

  Building and flying should always be done with adult supervision 

slip the elevator into the fin and mark the rib that will allow the elevator to pivot freely

cut one side of that rib and trim away the flashing

Cutting the slits in the hinge will help it bend easier. Work the hinge a few times to loosen it up.

Find the pattern for the wing tip and firewall---

and cut out the firewall pattern and stick it on the firewall wood with spray glue

Center the motor beams over the centerlines on the pattern. The horizontal line is the top of the motor beams.

Drill and use 4-40 blind nuts or bolt it on if you think you won't need to remove it. 

Our fuse is intentionally left a little long to fit a variety of motors. One this engine, K&B .20, no trimming was needed on the nose and I doubt if any trimming will be needed on most engines of this size, .20 to .25, so set up the engine as shown and check for nose length.

After setting up the engine and firewall, you will need to glue the two halves of the fuselage together. Use 3M 77 or other foam compatible spray glue or use Epoxy if you want. If use use spray glue, use some caution and do not put too heavy a coat of glue on the foam and be sure to let it dry before sticking the two halves together. If the coat of glue is too heavy or stuck before drying, it could melt the foam!

Check the prop to fuse doubler clearance before gluing to the fuse. 

Sand to foam to match firewall.

Sand the firewall edge to match the angle of the fuse all around.

bottom view

Locate the tank position, mark and dig the foam out.

Drill holes for the vent and fuel lines. This one is cut so the extra foam will keep the tank from slamming into the firewall in the unlikely event of a crash. Some soft foam was packed around the tank to cushion it also.

The fuel tank is laid out and cut in at this time. I like to go in from the left side of the fuselage, at about the center line, and dig a pocket that fits the tank snugly with about a 3/8 inch of foam left behind the firewall for strength and cushion in case of a crash. I like to crowd the tank close to the left surface of the fuse to give me a little extra foam on the right side to make a tunnel for the throttle servo rod without accidentally boring a hole into the tank.

You will have to accommodate the lines coming from your particular tank and a good way to help everything slip into place is to make the pocket long enough so that there is a little space for the fuel and vent tubes at the front of the tank area. After slipping the tank in, cut a chunk of scrap foam to wedge the tank in and keep it from sliding forward and possibly pinching the lines. Locate and drill holes for the fuel and vent lines and install the tank.

This is a Mustang Fuse but do the same to the Zero

Score the inside of the doublers to help them roll around the curve of the fuse.

You should now have a sanded fuselage with a firewall and tank installed so the next step is to prepare the fuselage doublers for gluing on. These are die-cut from 2mil coroplast material and will cover each side of the fuselage from about the back of the wing forward and will be long enough to make the side of a cowl. If you miscalculate and get the engine a little to far back, it is easy to trim the front of the doubler a little to make it fit.

Use 77 spray glue to stick the fuselage doublers on and be very careful to line them up to the wing saddles on each side. Now you will see why you scored the inside of the doublers. They should conform rather nicely to the contour of the sanded fuse and if you let the contact cement dry well, should mould themselves to the nose. You should also begin to see the shape of the lower edge of the cockpit. Spray a light coat of 77 spray glue over the rest of the fuselage and let it dry.

Slice all around going deeper with each cut.

Cut in at a downward angle.

After slicing it off, set it aside as it will probably need to be hollowed out a little to clear the servos before covering it with tape. It is helpful to smooth the interior area foam where the canopy came off with sand paper. This will make a smoother surface for the radio installation and fuse taping.

Cut a wedge to fit the top deck and glue it on.

Cut a wedge to fit the small portion between the firewall and the front of the wing saddle and glue it on. Leave about 1-1/2 inch long tail to glue and tape over the front of the wing after it is installed. It might handy to wait and staple this one on after the wing saddle is taped up. 

This would be a good time to double check the engine fit and location. Check the clearance for the prop/spinner and front of the cowl. Before you can do that you may have to trim the doubler to clear the muffler and you may have to punch a hole for the needle valve to poke through.

P51 fuse - but the idea is the same - fit the engine and make any clearance cuts for the muffler and needle valve.

After fitting the extra 2mil coroplast top and bottom, glue them on with spray glue. Use a hand tacker or staple gun to staple through the coroplast into the edge of the firewall all the way around. This will make the firewall very solid and able to withstand unbelievable crash forces. If you don't have a staple gun, use 1/2 inch wire nails, upholstery tacks, or even thumbtacks. Just be careful that you don't drive them through the fuel lines, if you have already installed them. 

Before proceeding with the taping, spray another light coat of 77 spray glue over the foam part of the fuselage and let it dry.

The strapping tape is installed. Note the flap extension from the bottom filler. This will help hold the front of the wing securely in place.

Cover the wing saddle with packing tape after the strapping tape is applied.

When strapping tape is wrapped radially around the nose and wing saddle, you will make the nose of the plane virtually unable to crush or buckle. The strength of this construction will be evident on the first ground plant.

The place to start is at the wing saddle. You should already have strapping tape covering the saddle from side to side so now we want to cover it with color. Start at the trailing edge of the saddle and lay packing tape across the saddle letting the tape run up the side of the doublers an inch or so. Keep laying in strips of tape with about a 1/4 inch overlapping the preceding strip until the saddle is completely covered.

After the saddle is covered side to side, you can cover the fuselage. First lay a strip of strapping tape along each side from the nose to the tail then start laying strips of colored packing tape on the fuselage from front to back. I like to start on the bottom and work up the sides. Overlap the preceding strip by about 1/4 to 1/2 inch until the whole fuselage is covered. Use the tip outlined above to help the tape conform to compound curves, unless you like lots of wrinkles. If you make lots of slits to help the tape conform, it is sometimes good to lay another strip of tape so that the previous slits are covered -- even if it means overlapping the strips of tape an inch or more.

If your plane will use the doublers to make the cowl, it is a good idea to let the tape run long enough to tape around the front of the doubler to cover the inside of the engine compartment all the way back to the firewall. After the fuselage and engine compartment  is covered, lay vertical strips of tape on the firewall, from top to bottom, to seal it.  

You should have the fuselage covered pretty well by now. If you cut the canopy off your plane, let the excess edges of tape wrap into the canopy area. You will have to slice it to get to stick smoothly. Check the canopy fit to see if taping changed anything, sand it a little if needed.

At this point you should have a fuselage that is completely taped up except for the belly scoop area. The tail group should be dry and ready to install now. I use a coat of 77-spray glue on the part of the tail that slips into the fuselage. Now, you have to be fast so have the slot in the fuse open (slice along the covered up slot and push the excess tape into the slot) and ready to receive the tail group. Then, quickly spray a wet coat of 77 glue on the parts of the tail that fit into the fuse. Before the glue starts to set, slide the tail into the slots of the fuse. Make sure the fin is straight and true with the centerline of the fuse and squish the sides of the fuse onto the fin. If you are not careful, it is easy to give your plane a permanent right or left turn by bending the back of the fuse one way or the other. The goal here is to assemble the tail group and fuse while the glue is still wet to allow a little slippage so they can be aligned properly---good luck,

work fast! Apply a strip of packing tape under the fuse to close up the tail slot, then run a small bead of Goop on either side of the fin to stick and seal the tail to fuse joint. Block the fuse and tail so they will cure in good alignment.

You should now have a completed airframe ready for radio gear and wing installation!  

 Shape the bottom of the wing tip, then sand the center and wing panels smooth. Then check the dihedral.

This picture is a little confusing but the wings are Epoxied to the center section and blocked so they cure at the right dihedral. In this case about 1-3/4 inch from the table to the top of the tip.

After the wing halves are stuck together, run four strips of strapping tape from wing center to each tip,  top and bottom. Dihedral wings are hard to do in one length so I start across the center section to each tip. Use a slight stretch on the tape. If the wing panels are bowed up or down, pull harder on one side to correct the bow. 

After the strapping tape reinforcement is on, use the colored packing tape and tape chord-wise from the center out to about 10". overlap each successive strip of tape about 1". Do that top and bottom and let the ends of the tape wrap around to leading or trailing edge to the other surface about an inch. The main idea here is to use lots of tape to beef up the center of the wing because the wing takes the most stress from the joints to about 10" out the wing panel. 

You can use the method at the right to attach the ailerons or this alternate method. After setting the correct fuse to aileron clearance and with the wing upright, use small peices of strapping tape to position the aileron about an 1/8 inch gap between it and the back edge of the wing. Then lay a strip of strapping tape over the gap, lining the edge of the tape up with the back edge of the aileron. Incidentally, I seldom encapsulate the aileron in tape anymore. Just leave it natural and tape it on.

After the top tape is on, flip the aileron over and use a piece of masking tape to temporarily hold it in position and stick a strip of packing tape along the edge of the aileron, full length, and wrap it around the back edge of the wing and aileron.

This is a bit difficult to see but the tape wraps around the back of the wing and aileron. Open the aileron up and use a blunt object to stick the top and bottom tape together to form the hinge.

Like this!

After the ailerons are on, use the wing tip pattern to trim them to the correct shape

Start the finish tape on the bottom first.

After applying the strapping tape to the wings, it is time to prepare the ailerons. Cut the ailerons from the elevator sheet. Make the ailerons about 1/2 wide and, if you use the full length of the elevator sheet, should be just longer than the wing panels. The ailerons are just right if you slice the coroplast so that two complete ribs remain with half a rib left on each side - see fig 4. Position the ailerons so the inboard edge will clear the fuse by about 1/4 inch. These will be encapsulated in tape before they are attached to the wing (see fig. 4). 

Don't worry about the wing tip shape of the ailerons because we will use the wing tip pattern to trim them after they are covered and attached.

Tip: when covering the ends of thin parts, trim one side off at the edge and wrap the other over it---just like when using iron-on covering.

 After covering the ailerons, lay the aileron upside down on the wing (see fig. 4). Run a strip of tape along the back of the wing and the aileron, smoothing the tape down on both surfaces, then open it up, lay the aileron flat and apply a strip of tape along the top of the hinge line. Turn the wing upside down and use a blunt object (window screen tool works perfectly) to press the top and bottom tapes together to complete the hinge. Do this to both ailerons and after they are attached, start the final taping.

When covering wings with packing tape, always follow this simple taping convention: Always start at the back and work forward overlapping about 1/4". This way the tape edges will flow with the wind instead of pointing into the wind. Another good idea is to always start with the bottom of the wing so that the finished wing always has the top tape wrapping over the bottom surface. It just looks a little neater.

With dihedral type wings, it is always easier to tape from the middle out to the tip. Start at the trailing edge and lay the regular 2" packing tape across the wing from the middle to tip. Let the center over lap the far seam about 1". Let the tape run long, leave the ends stuck to the table until the surface is covered, then with a razor blade trim to about an inch long and fold around the wing tips before covering the opposite side (this gets a little difficult when taping the bottom of a dihedral wing so I lay the wing upside down on the edge of a table with half the wing hanging off the table, then work on the half that is supported by the table). 

TIP: when trying to tape around a compound curved surface like wing tips with packing tape it will tend to bunch and pucker. Before pulling the ends over the wing tip, slice the edge that is hanging over about every ½", then starting at the back, working forward, smooth each little flap of tape over the round edge. The little flaps will overlap each preceding flap and the curve will be much smoother.

Again, always apply the tape from trailing edge to the leading edge with the typical ¼" overlap. The leading edge should have a couple layers of tape wrapped around it by the time the top and bottom covering is done. We recommend adding another layer or two of tape to the leading edge for extra protection. Stretching the tape modestly while sticking it down will help it go on smoothly but be sure to balance the stretching or you could have a wing that bends up or down.

The control throws should be about 1/4"  up or down. This will make the plane very easy to control at high speed.

After the servo is cut in and you are certain of it's placement, slide it out for a second, coat the edges of the foam pocket with silicone and slide it back in place. Wipe the excess off and be careful not to get it on the fuselage or wing where more tape would go.

Hold the wing to the wing saddle in the fuse and eyeball where and how much clearance you will need to cut into the wing saddle for the servo. You will have to cut a hole in the fuse doubler for the pushrods to exit the wing saddle and there will have to be enough cut out so the servo arms and pushrods will work without binding on anything.

It is a good idea to hook the servo to your receiver to check for correct and smooth operation because the wing will be glued on permanently very soon.

The radio gear will be mounted under the canopy so bore a 1/2 hole through the fuse to route the aileron servo from the wing saddle to the canopy area.

After the wing is taped, locate the servo and cut it into the wing. Mark a rough location for the foam to be dug out of the fuse for clearance.

Dig the foam away so the servo arms and pushrods will not bind.

Most servos will come through the bottom of the wing.

Use scrap coroplast to form a protective box around the servo and cover it with another piece.

Tape over it and the servo will be protected.

Notice this plane is balancing on sharpened pegs. Here's an easier way to balance it: Don't turn it upside down,  just mark the balance point on each side of the fuselage and grasp it, between your thumb and forefinger. With practice, you can tell pretty well if it is balanced OK. 

This is the cockpit layout for the Zero, notice the receiver in upper right. Just below that is the FMA S80 throttle servo in the lower right. To keep the weight down I used our BA 350 battery pack, upper left and an FMA S100 servo for the elevator, bottom left. No switch is used for this combat plane but it could be cut in any where that is convenient.

 Try to make everything accessible from the canopy area. When you have determined the best positions for the servos and radio, mark a line around them and use a knife to cut the pockets in the foam. Use a gouge to dig the pockets out and be sure to keep the fit as snug as possible. Find a convenient place for the switch. Make a hole for it or cover it with tape and use a piece of piano wire to operate it. Leave the charge cord accessible also. After the pockets are cut, if necessary, bore a hole from pocket to pocket to route wires through for a neat looking job. A 1/2" diameter tube sharpened on one end works great.

Servo installation

Thread the wires through the holes and hook up the plugs. Now is a good time to center each of the servos and make sure of the control wire lengths. Before sliding the servos in for the final time, coat the pocket sides with silicone sealer. This will hold the servo in place and the silicone is not too impossible to remove. Try not to get silicone on the plane because tape will not stick to it! If you do, wipe it off with mineral spirits (paint thinner). Tip: wrap the servo with tape so the silicone can be easily peeled off if you take the servo out. If you mount your servos externally, tape over the servos leaving the shank sticking out. I must stress again to make the servos fit snugly. If you want them to fit flush with the surface you are imbedding them in, you will have to create a pocket that is sort-of two stepped to clear the mounting flanges on the servos. This will allow the servo to sink further in and will keep the control arm as close to the fuselage as possible. Another great idea is this: If you intend to do a lot foamie plane flying, just cut off the servo mounting flanges and sand the bumps smooth. This will allow the servo to slide down into a nice, neat, straight-sided pocket. Of-course you won’t ever be able to screw the servo down again, but if you get into foamies, you won’t ever need to!!!

Set the control throw for the elevator at 1/4" up from center and 1/4" down to start. Since small planes tend to snap roll, some combat pilots suggest starting the control throws at no more than 1/8 inch up and down and gradually increasing them until the plane turns the sharpest without snapping.

While the wing is curing, the canopy can be taped up and fit. Since the radio gear is installed, you will probably need to carve out some clearance for servos and other gear so the canopy will fit. Set it aside as it will be the last thing to install just before flying.

The canopy can be painted gray or silver with Krylon spray paint and decorated with automotive pinstripe. I sometimes use 1/4 inch black pinstripe to hold the canopy on around the edge or you can tape it on with clear or colored tape and touch it up with silver paint. 

You can decorate it with different tapes or decals. If you have a computer and a drawing program, make up some red circles and stick them on the wings and fuse with spray glue then tape over them with clear tape. 

The main thing is to have fun with this plane. This is designed for a .20 to .25 size 2 stroke.  .40 size engines would be outstanding and a geared electric would work fine too.

This is the finished plane. The white tape was sanded with 220 wet/dry sand paper (the black kind) until the shiny stuff came off, then different shades of green Krylon were used for the mottled cammo look. Red round dots were made on the computer and yellow electricians tape made the leading edge of the wing stand out. This one shows the fuselage doublers taped in black and forming the cowl. The Zero page has a shot of the same plane with a pop bottle cowl on it. Combat!?? anyone? If you want to see a detailed discussion on how to paint a taped up plane, go to the tech page and click on the "How to paint the foamie" link. Or use the link here.