Prior to covering the structure I used a fine drill bit and a No. 11 blade to open slots for all the control surface hinges. After the last primer coats were dry and sanded out, I opened up each slot with the same No. 11 blade and dry-fitted a hinge (DuBro No. 117) into each slot to check the fit. I'll push this hinge all the way in to make sure it fits without binding before I go anywhere near it with adhesive.

Regardless of the adhesive you use to assemble pinned hinges to the airplane structure you must make sure it doesn't infiltrate the working portion of the hinge and cause it to bind, or stick, or worse yet, lock up. OIL is the answer...any adhesive you are likely to use won't stick to it. I'm using a needlepoint oiler with ordinary light machine oil on the entire mating portion of the hinge. Get the hinge line WET with oil, but don't let it run out onto the flat attachment tabs.

I'm using ZAP A GAP to set the first side of each hinge...here I'm working on the elevator...because I'm dealing with one hinge at a time and I can concentrate on getting it aligned without worrying about it's neighbors. If you're not confident you can do this, use slower setting epoxy instead.

Here's the hinge pushed all the way into place with any excess "squeezeout" of adhesive wiped away.

I'm pressing the elevator leading edge against my flat work surface to make sure each hinge assembly in turn is parallel to the leading edge. (On a larger airplane with removeable-pinned hinges I'd do this by inserting an alignment rod through each hinge and into the next as I installed it.)

The hinges are in place in the elevator, recessed into the slots I cut for them, and aligned as neatly as I can get them. At this point I wipe each hinge assembly CLEAN of any remants of oil and cured adhesive, double-check it for freedom of movement,and re-oil the working joint before the final step.

Now we are looking at one of the ailerons. ALL of the hinges on this surface will have to fit into the trailing edge at the same time, so I chose a thirty minute epoxy to guarantee that I'll have time to get all of them lined up exactly and any dribbles of excess epoxy cleaned up before it starts to cure. This is one of those no-second-chance deals. If you ever have to cut misaligned hinges out of an assembled control surface you'll find out what that means.

I'm slipping the entire left aileron into place FOR KEEPS...the outboard hinges are doing just what this one is, with wet epoxy on them. The control horn is slipping into the pocket prepared for it in advance. You can be sure I double-checked THAT as well before mixing any epoxy.

Last chance...I'm using my trusty old artist's pallette knife to lift away any little globs of epoxy that squeezed out as the hinge was pushed into place. A little squeezeout is good...it ensures that the internal joining surfaces are fully wetted with adhesive. You can't see a dry joint, but you'll recognize one when it fails.

I use strips of masking tape wherever I need them to lock the aileron...and the other surfaces...into exactly the alignment I want, and then go away to do something else for a while to be certain the epoxy has had time to cure hard before I move anything. All the hinges on all the control surfaces go in the same way on this airplane.

Cockpits, canopies, windshields and so on are FUN. They are also attention grabbers on any model where the builder has invested some effort beyond a plastic bubble taped to the top of the fuselage. The TigerKitten is not a scale model, but I designed it to look like one...you really need a cockpit, and in this case a windshield, that looks believeable. The cockpit cutout and backrest are pretty much dictated by the way I designed the airplane, but the details can make all the difference. On this model I'm going to represent a simple unframed single curvature plexiglass windshield which in the real world would be molded to shape and attached to the top deck with a formed metal or plastic base fairing secured with either rivets or screws. On the model I can hand form the plastic windshield, attach it with ZAP, and then build up a fairing strip using filled epoxy. And...I'm going one step further. If this were a full scale airplane there would be some sort of matte, anti-glare feature on the top deck inside the windshield above the instrument panel. I'm going to represent that with a piece of brown suede-finish paper from the craft store. At this point I have marked the line where the windshield will meet the cowl by tracing the dry joint with a pencil, then rough-cut a piece of my suede paper big enough to cover the inside surface with a safe margin for error.

The next step is easy. I used spray-on contact adhesive on the back of the suede paper, positioned it to cover the area I marked out, and pressed it into place.

Now I can go back, dry-fit the windshield again, and mark onto the suede paper where the attachment line will be. With that done I ran a strip of masking tape along the INSIDE of the curve to serve as a cutting guide and protective covering.

Put a fresh (sharp) blade into the knife for this job...you want to be able to make a clean cut through ONLY the paper without having to press down hard. I'm trimmimg away the excess suede...the part that would have been outside the windshield...so I'll be able to attach the clear plastic to the cowl, not to paper.

Now I can peel away the extra paper.

I cut the windshield to shape using the pattern on the plan, then covered the entire outside face with several layers of masking tape leaving only a narrow margin...about 3/16"...for attachment. Here I have fixed the outer edges of the plastic in place with masking tape and I'm using ZAP A GAP to build a neat fillet along that exposed edge of the plastic where it meets the cowl.

The sides of the windshield are firmly ZAP'd in place. Now I'm pressing the front edge firmly in place against the cowl, ready for more ZAP A GAP. Zip Kicker accelerator is a must for an assembly like this.

With the entire bottom edge of the windshield fairing ZAP'd in place, I ran a single strip of 3-M Blue fine line automotive masking tape along the bottom of the masked area to ensure a sharp definition, then added a double strip to define the outer edge of where I want the the fairing to be.

There are all kinds of lightweight epoxy putty/fillers around. In this case I made my own by adding talc (baby powder) to some thirty-minute epoxy. I'm using that same artist's pallette knife to build a fillet of epoxy putty up and over all the tape edges. NOTE: Do not use a solvent-based balsa filler product for a job like this. It will shrink as it dries, crack, and ruin your best efforts to do a neat job...and...it will impart zero strength to the joint.

A WET finger is an excellent tool for smoothing the fresh epoxy putty to a smooth contour as close as possible to the finished shape you are looking for, in order to save sanding later.

The cured epoxy can be sanded to a finished contour. Here I'm using 220-grit silicon carbide paper wet. There is no substitute for care and patience doing this part of the job.

Ready for a primer coat. I have finish sanded the fairing strip to form the smooth, concave curvature I want and to cut the surface of the epoxy putty material down level with the top of the various strips of masking tape. That way when I pull the tape I get a crisp edge equal to the thickness of the tape buildup. This simulates the edge of a sheet metal fairing. I'll leave the tape on the windshield until after all the paint is on and then pull it to get a similar raised edge on the opposite side of the fairing.

I'm using a wide, flat, soft brush to put the first coat of clear dope onto the bare covering. At this point any fabric or paper covering is going to soak up dope like a dry sponge. What you need to do is to brush on a generous wet coat of dope that's as heavy as you can manage without letting the wet dope sag or run...you want to get every square inch of covering saturated .

Dope...especially nitrate dope...dries fast, but not always as fast as you might think. Usually this takes a couple of hours before the coat of dope is dry enough for light sanding. The doped surface may feel firm and dry before it really is. If you can touch the doped covering and feel any sensation of coolness (from evaporating solvents), it's still NOT dry. Wait. When it is dry, I use 320 grit production paper very lightly to cut off the tiny "fuzzies" that appear on the covering. DON'T press hard enough to cut into the fibers of the covering material.

Here's the rear fuselage and fixed tail surfaces after one coat of dope and sanding as I just described. This is the point at which a doped tissue or fabric covered model begins to come alive. The doped covering bonds to every part of the airplane it touches and the whole thing becomes a taut, crisply vibrant structure, with an air of authority that no film covering will ever come close to matching. It's got soul.

Once the first coat of dope has been sanded out, I add the second. You can't see it, but at this point I'm switching from ordinary (shrinking) clear dope to non-tautening dope...the covering is now as tight as I want it to be. Shrinking further would threaten to distort and twist the structure, which is not good.

This is how the Polyspan covering looks after the second coat of clear nitrate dope has dried. The difference in appearance from the first coat is subtle, but it's there and you can learn to recognize it.

I'm giving the second coat a light sanding with that same 320 grit production paper. Most of the "fuzzies" that appeared after the first coat dried are gone now and the surface I am sanding feels smoother. However, it's not fully sealed yet, so it's still too soon to let the paper begin to cut into the surface.

More subtle stuff...I've given the wing its third coat, this time with my dope/talc mixture. For places like this, I mix my sanding primer with enough talc to give it the consistency of heavy cream.

Now I am beginning to sand aggressively enough to cut into the surface of the dope/talc coat. If you look carefully you can see loose sanding dust (talc) on the wing surface. Knowing exactly how much to sand, how hard to press, is a set of skills you can only develop over time, with practice. It it worth the effort? Take a look at some of the other airplanes I have presented here on rcmodel.com and YOU decide.

I put two wet coats of dope/talc sealer onto the entire airplane, sanding meticulously after each coat dried. Now I have switched over to Stits Lite Coat primer...that white stuff...to get a totally opaque surface. This accomplishes two things...it makes spotting whatever flaws and blemishes are still there so they can be given extra attention with the sandpaper, and it will provide a uniform base that requires a minimum of Stits Polytone (color) to cover evenly. (Color costs more and weighs more, which is why we use as little of it as possible.)

It's judgment call time. When the first shot of Lite Coat dried, it permitted me to see tiny bumps and wrinkles that weren't visible before. I mixed up a small batch of really thick dope/talc to use as a spot putty and dabbed it onto each of the problem spots with my pallette knife. Here you see it still wet as I'm applying it to the horizontal stabilizer. Be careful here... adding a surface filler like this over a fabric covering demands a fine touch. Nearly everything I'm putting ON here will have to be sanded OFF without permitting the sandpaper to cut into the covering. That's going to take a really delicate touch to pull off, and it's something you'll want to consider carefully before you do it on YOUR model for the first time.

This is the same dope/talc filler on a bad spot I found on the wing, after it has dried.

I'm using one of my long, straight sanding blocks with 320 grit production paper to cut the spot of filler on the wing down even with the surrounding surface.

Same deal with the horizontal stabilizer. This is where it pays off to learn to sand with a slow, gentle touch.

The final smoothing and blending of the last little traces of an edge on the patched area is done with more 320 grit and calibrated fingertips. In fact, you can very often FEEL an irregularity at this stage of a finish job when it's difficult to SEE it.

Sanding out the Stits primer coat surface on the underside of the wing center section. You can see the dust on the work surface and on me. Surprisingly, the most common error at this point is not sanding too aggressively as you might suppose...it's not sanding PATIENTLY enough and leaving extra primer, along with visible roughness and extra weight, on the surface of the airplane.

Here's another look at the way Stits Lite Coat primer should appear after you've sanded it properly. I have sanded into the primer coat as far as I can without cutting through the final bit of dope over the covering, and the primer is GONE from what used to be the high spots.

Another look. This is the horizontal stabilizer after I've finished sanding out those little patched spots.

This is a wingtip after I sprayed more of the Lite Coat over the fully sanded wing. You can see how smooth the entire surface has become, and how the uniformly white surface is going to be easy to cover with a minimum of color.

I'm sanding...very gently and very selectively...one last time before it's time to spray color. It's also time for another judgment call. At this point the base coat surface is GOOD, but it's not PERFECT. I could go through two or three more cycles of spray-dry-sand, getting down to 400 grit or even finer wet-or-dry paper, but I'm not going to. This TigerKitten is a club field, Saturday afternoon sport airplane, not a candidate for concours honors. I could get a better finish, but it would be at the expense of several additional ounces of weight. Like a lot of other activities, the trick to success here can be knowing when to stop.

One last look. Here's the horizontal stabilizer again after I've just brushed over it with the 320 grit paper. Now that they look like this, I'll dust ALL the surfaces off, give them a light wipe with a paper towel and denatured alcohol, and consider them READY FOR COLOR.

My pre-production kit included a sheet of plastic bearing all four half-pants in a single matrix. Here I have already rough-cut each half free, just a bit oversize. You get two left and two right halves...this is how they'll fit together.

These moldings are drawn really deep...there's nearly half an inch of plastic extending past where each molding must be cut to fit together into a wheel pant of the correct width. Compare the part in my hand in the previous photo to the one I'm trimming here. Mark a line in pencil or with tape so you know where the cut needs to be, then trim the excess plastic away. Here I'm using short, curved-blade snips (scissors) from the hobby shop that are ideal for jobs like this.

A big sanding block is the best way to square off the trimmed face of each part. Here I have taped a sheet of 80 grit production paper flat against my work surface to ensure cutting a true joining face onto each half of the wheel pant assembly.

This is how the trimmed halves of each wheel pant are supposed to fit together. You can see the smoothly rounded front in the previous photo; this is how the rear end should look...just rounded off, not a sharp point and not "wide and clunky" the way it would look if you hadn't trimmed and sanded away enough of the matrix.

When each wheel pant half is cut to the correct shape, we need to mark where the opening for the wheel is going to be cut. This has to happen next, as we can't get inside the assembly to join the halves without an access hole.

Those curved snippers are just right for roughing out the wheel opening. Don't cut too deep!

I used a coarse rotary cutting bit in my drill press to clean up the wheel opening. I prefer this to using a hand tool, such as a Dremel, because I can depend on the solidly mounted power tool to be exactly where I expect it to be while I use two hands to guide the workpiece. (Yeah, you noticed that the tool is turned off...I'm using my right hand to hold the camera just now!)

With the wheel cutouts made, I joined each pair of halves into a complete wheel pant using masking tape. At this point the left and right assemblies are identical.

There are a number of ways to join the halves. On this airplane I'm depending on a generous bead of SLO ZAP flowed into the inside of the assembly. I then rotated the part to let the heavy, wet bead flow along the entire length of the inside seam. When it had spread out evenly I gave it a shot of Zip Kicker. On a bigger, heavier model or one intended to be flown from rough fields I'd have included a narrow strip of fiberglass cloth along the seam, saturated with more ZAP. Since I have the luxury of flying from well tended grass fields I elected to leave that out to save a little weight. (Post-flight report...it works just fine this way.)

You can just see the cured SLO ZAP filling and bonding the inside seam. There is still some trimming left to fit the cutout neatly to the wheel.

When finishing cutouts like this one, at some point I like to go from the power tool to a hand-held sander in the interest of precision and caution. This is one of my favorite tools...a piece of production paper of the appropriate grit wrapped around a tube or dowel or bottle that happens to be the right size for the job at hand.

Sanding the outside of the seam is less intricate, but it's just as important. This is 80 grit autobody abrasive on a block. At this point you need to sand until the only sign left of the joint is the rough place where it used to be... then you switch to finer paper and sand that away. Joint seams on the outside of finished wheel pants are a sign that somebody forgot to learn about patience back in kindergarten.

I messed up and lost the image that I wanted to show you here, illustrating a piece you can now barely see as it was being assembled. There's a lamination, or backing plate, of 1/16" plywood about 1 1/4" square inside the face of the wheelpant where it's going to mount against the landing gear. With that in place I marked the opening that will allow the assembly to slip into place over the assembled wheel and went back to the drill press to cut it out.

This is the landing gear, with the axle and wheel in place, over which the cutout I just made is going to fit. The little rectangular aluminum mounting plate is made per the plans, drilled, and captured by the axle nut against the gear leg.

Just so I can say I showed it to you, here's the same wheel and axle assembly from the other side. On this little airplane the outer face of the wheel pant will float free over the axle end and wheel collar.

The assembled wheel pant is held in place with masking tape in exactly the position I want it to be mounted.

I used a soft pencil to mark through the holes in the mounting plate onto the face of the wheel pant to locate drill hole locations.

While you weren't looking I drilled the holes in each pant assembly to accept this 2-56 tap. Those short litle 2-56 cap head screws will go through the mounting plate and lock into the the threads I'm cutting now. This saves messing with separate 2-56 stop nuts inside the wheelpants, where they are hard to get to when the screws get loose. (In real life, once I'm satisfied that the pants and wheels won't have to come off for a while I'll put a drop of light LOCTITE on each screw.)

It's time to start covering. Prior to getting to this step I've given the entire structure a heavy, wet coat of non-tautening clear nitrate dope. When that was thoroughly dry I sanded every surface that will come into contact with the covering with 320 grit production paper to get rid of all the little bumps and fuzzies that could cause snags. The other reason for this pre-doping is to seal the balsa so that the covering adhesive won't soak in, but rather stay on the surface where it's going to be needed as the heat activated stuff that grabs and holds the covering. Here I'm using a soft, round brush to put a generous bead around the entire outline of the wing...everywhere that the Polyspan must be adhered. I'm using fabric formula Balsarite, but there are other brush-on, heat activated fabric adhesive products that will work just as well.

I'm starting with a single piece of Polyspan cut to cover the entire bottom surface of the right wing. Since there is a severe concave compound curve formed by the lower leading edge fairing, I cut out a relief section to permit the the main sheet of covering to lie flat around it. The Polyspan is cut exactly to the dimension I want it at the centerline of the wing but left with plenty of overhang (for now) everywhere else.

Stick it! I'm using an old reliable covering iron from Hangar 9, set to about 250 degrees, to activate the adhesive without causing any significant shrinkage of the Polyspan. I'll work back and forth along this line, varying the pressure of the iron as necessary. The goal is to get the covering stuck firmly in place without any wrinkles, folds, or loose spots.

With the Polyspan stuck down along the wing centerline we have something to pull against to begin stretching the sheet smooth across the entire panel. Here I'm using the iron to adhere the covering at the inboard end of the leading edge securely down and around the front of the structure.

Next I pull the sheet of covering taut spanwise and adhere it at the outer edge of the tip assembly.

With the covering held in place at the root and at the tip, I can work along the leading and trailing edges in between and pull out on the covering just hard enough to make it lie smooth.

This is the center section with the edges of the covering adhered all around the perimeter. You can just see where the activated adhesive has turned the covering nearly clear in appearance where it's wrapped around the leading edge.

I left the lower leading edge fairing uncovered until now. I cut a separate piece of Polyspan that can be worked over and down around the edges of the fairing.

Activating the adhesive on the small piece of Polyspan over this deeply curved fairing demands care. In a place like this you have to make the necessary extra effort to press and pull and push with the tip of the iron to avoid leaving any small patches of covering unadhered to bridge across tight curves and corners. Any such bridges will come back to haunt you as persistent flaws in your covering job if you ignore them now.

Now we're working on the top surface of the wing. I've repeated all the steps I did on the bottom and now I have to deal with something new...the aileron horns. The trick to this part of the job is to make a small cutout that allows the covering to lie flat around whatever protruding part you're dealing with and iron the material down tight around it.

This is the top surface of the right wing tip. I'm pulling and stretching the covering out, down and around the outer radius of the wingtip. Be sure to go over-center in places like this to guarantee that you'll get a double overlap of the covering.

Here the covering has been pulled tight around most of the tip and lies flat across the trailing edge...actually the aileron well on this airplane.

I've made a diagonal cut in the covering and ironed the small triangular tab down and around the inner surface of the tip structure.

Now that last little end of loose covering around the rear end of the tip is stuck in place...and...I've wrapped the main expanse of Polyspan around the front of the aileron well. There's a good overlap created here since the bottom surface covering already extended around that same edge.

I treated all the free edges of the covering around the trailing edge/aileron well the same way. With the entire wing panel...top and bottom...covered, I can begin shrinking the Polyspan tight. NEVER shrink the covering before both the top and bottom are covered. That's a good way to introduce uneven stresses and create warps. Just to the right of the iron you can see a few shallow sags that have yet to be shrunk tight.

This is what freshly applied Polyspan should look like after being ironed at 275 - 300 degrees. There should be no bubbles around the edges and no puckers or wrinkles anywhere.

I covered the control surfaces and the fixed horizontal stabilizer just the same as I did the wing. Now it's time for my favorite part...covering the fuselage. On this airplane we're going to incorporate a classic feature, the fabric fairing between the vertical tail and the rear portion of the fuselage. This is a characteristic of many of the old time fabric covered airplanes you might want to model. You can't fake it...but it's not that hard to do right if you know how. Here I'm starting by covering the bottom of the fuselage from the wing cut-out to the tailpost. I started by adhering the covering along the front of the area...just as with the wing,I want something to pull the rest of the job tight against.

Next I pull the covering taut along the length of the fuselage and iron it down over the tailwheel mounting plate.

The next step is to pull the covering smooth across the fuselage and iron it down around each of the lower longerons.

With the aft bottom covered, I use a fresh (sharp) razor blade to trim off the overhang along the upper (inside) edge of each longeron.

Here comes the fun part! I have cut a sheet of Polyspan that reaches from the tailpost (the vertical fin trailing edge) all the way past F-1, and far enough up and down to provide a generous margin around the bottom longeron and the top centerline of the fuselage...including the entire vertical fin. I have cut a slot as precisely as possible to permit that sheet of covering to slip around the base of the fixed horizontal stabilizer (which I have already covered.) Watch what happens next.

I pulled the sheet back so that the front of the cutout fits snugly around the leading edge of the stabilizer and then adhered the covering all around the base...top and bottom.

Just to be sure I have everything under control, the next step is to adhere the covering along the front of F-1 (at the nose). I don't want to get through the next few steps and then discover that the covering for the front part of the fuselage is out of line.

Now it gets interesting. I have adhered the Polyspan all along the tailpost/fin trailing edge. You can see where I have pulled it taut vertically...from the stabilizer toward the fin tip.

The next step is to adhere the Polyspan all along the lower edge of the fuselage including the rear longeron, the outline of the wing cutout, and the bottom edge of the nose. Again, the covering must be taut and smooth at this point, with no folds or deep wrinkles. We'll get it TIGHT later.

Now we need to get the covering to fit into the complex curvature created by the fin leading edge and top rear of the fuselage. I start by slitting the covering down as close as possible to where it's going to lie against the top center stringer and the fin leading edge AFTER I've pulled it tight. This requires good judgment..take your time. If you cut past the top stringer you'll have a hole to deal with.

Here comes the big secret to advanced fabric covering technique...pull, stretch and pull some more. The next thing I'm going to do is iron down the covering along the several inches right next to my thumb.

Now I do the same thing all the way around the fin leading edge. If you like, you can do some testing on scrap to determine how much you can pull on the covering material before it will tear. Usually that's more than you expect.

Now let's go to the cockpit area, slit the covering there, and work it around the rear fuselage top and back along the dorsal (center) stringer.

All in place. Every edge is stuck down with plenty of structural overlap. The covering won't be smooth at this point, but it must be free of puckers and creases.

This happens to be the opposite side of the fuselage. I covered it just the same as the first.

With both sides of the fuselage and fin covered, I then did a final heat shrink of the entire fuselage.

Here it is again from the other side, with the first coat of clear nitrate dope applied.

In the TigerKitten the servos, receiver, ESC and battery pack all mount to a 1/16" aircraft plywood tray that fits into the center portion of the fuselage. This requires that you build in these 1/4" square bass (or spruce) rails along the inside of the fuselage doubler on either side and then provide for hold-down screws. This involves a bit more work than simply glueing the tray in place, but it offers the real advantage of being able to remove the tray...and leave the entire center area of the fuselage open...for repairs or modifications. The difference in weight might be measurable, but it's inconsequential. When I got the 1/4" square rails installed I wasn't satisified that the fit between the plywood tray and my fuselage as I had built it was going to provide enough area for the mounting screws to hold securely, so I added the doubler/reinforcement blocks you see here, made from leftover 1/4" square. (Note that there are two more out of the image near the nose.)

Here I have measured and cut out the opening at the rear of the tray for the rudder and elevator servos and added a pair of 1/4" sq. bass rails across the tray to hold the servo mounting screws. I chose to mount these servos upside down so that the rudder and elevator control tube connections will be accessible when the wing is off. My mounting hardware is No. 4 x 1/2" button head sheet metal screws (DuBro Cat. No. 527)

I'll have more to do inside the model later. Now it's time to add the rudder and elevator control horns. I'm using DuBro nylon control horns (Cat. 107), which are intended to be attached flat against one side of the control surface with two screws extending to a backing plate on the opposite side. There is nothing wrong with doing it this way...but...I am a fussy all-out scale fanatic and I like to reproduce credible "scale" appearance even on my sport models. To get rid of the clunky-looking backing plates I chose to inlay each horn base into its respective surface. Here I have traced the "footprint" of the rudder horn.

I used an ordinary No. 11 blade to trim around the marked outline down to the thickness of the base (about 3/32"), and then a curved miniature wood chisel to create an opening for the horn to slip into.

Once I had checked that the rudder horn rests squarely in place in the opening, I wet the inside of the cutout generously with ZAP-A-GAP, pressed the horn into place, then flowed in more ZAP-A-GAP to create an outer surface flush with the rest of the structure.

A shot of Zip Kicker ensures that the thick application of ZAP will cure quickly and thoroughly. NOTE: This method of control horn installation works well for small, light airplanes, but may sacrifice some of the strength of the screw-through feature. It's fine on a three pound sport model like this, but once the model in question gets much bigger you need to be using plywood insert horn bases along with nuts and bolts to hold everything together.

It's time to provide an opening for the control connection to the servo. This happens to be the marked location, per the plan, where the elevator push-pull tube assembly will exit the fuselage.

I'm going to use a concentric tube-within-a-tube connector system here. The hole through the side of the airplane must allow the outer (thicker) tube to fit snug, but also to lie straight in a line from the control horn to the servo output. To get this right you start with the locations marked on the plan, measure and fit and check, and adjust as necessary. Be sure your hole is elongated enough that the outer tube won't try to make an "S" curve as it passes through the sheet balsa. I'm using a round wood rasp (file) to cut the clearance I need. NOTE: I can't assume that every "new guy" knows this...that sheet balsa insert is absolutely necessary to provide an anchor for the tube and to support whatever covering you use...film, fabric or whatever...around the tube exit. The control connection can't be allowed to flop around loose.

These concentric control tubes won't support themselves over the distance between the servo output and the exit hole...unless they are braced securely they will flop around under air load pressures and cause erratic control responses. Here I've drilled a simple piece of 1/8" sheet balsa cut to fit at the F-6 station, to support the front end of the rudder and elevator tubes. (I have the inner tube "dummied" in place and lined up with the servo output at the front.) Thin ZAP will work best here to hold everything in place once I have it located correctly.

This is the outer tube for the elevator. With everything aligned, I ZAP'd it in place in the balsa sheet support insert and then cut off the end to form a neat control exit that will blend into the finished covering as a streamlined fairing.

Same deal as seen from the bottom. The tube on the airplane's left (it's upside down) is for the elevator; the other is for the rudder. The tubes cross inside to permit as straight a run as possible from servo to control horn.

I'm using DuBro pinned nylon hinges (Cat. No. 117) for all the control surfaces. This is the rudder. You can just see a temporary wrap of masking tape at the right of the hinge...this holds the surfaces in alignment while I mark hinge locations as per the layout shown on the plan. I'll extend these simple pencil lines around the edges of the surfaces once they are separated.

Here I am working on the vertical stabilizer, using a 1/32" bit to drill a hole all the way through at the exact center of trailing edge at each end of all the hinge locations I just marked in pencil. These will define the hinge slots. With the holes drilled, it's easy to cut out the balsa between each pair of holes with a NO. 11 blade.

Back at the rudder...I've drilled and opened up all the hinge slots and dry-fitted the DuBro No. 117 hinges in place. NOW is the time to sand, trim, or otherwise fix the control surfaces so they all fit like this without forcing or binding.

Here's another look at the tail with the rudder and elevator in place. Everything is fitted dry (no adhesive) at this point. I'll install the hinges for keeps after all the covering and finishing work is done.

I'm using the same pencil line technique to mark the hinge locations on one of the ailerons.

As with the rudder and elevator, I'm drilling 1/32" holes at each end to define the hinge slots.

After drilling, I use the No.11 blade again to cut out each hinge slot. There are various "machines" around to do this job for you, but I have discovered that I prefer the blade and drilled stop holes as the easiest way to make controlled cuts and open each hinge slot exactly where I want it to be.

Because the front of the aileron includes an angle that creates a narrow leading edge, it's easier to get the aileron to fit snugly against the wing cutout/trailing edge if we cut a relief slot in which the center pinned section of the hinge can rest. I'll sand the surface of this cutout smooth after I finish trimming.

This is the right aileron in place with the control horn and the inboard hinge dry-fitted. You can see how the hinge nestles into the shallow slot I just made for it.

This is the "raw" cowl molding after I trimmed away most of the overhang, or extra plastic from the original matrix. This particular "pull" did not result in a clean, definitive transition from the matrix and so leaves some question as to exactly where I need to cut to get a cowl that will fit the rest of the airplane. Rather than go looking for another part, I'm going to show you how to fix this on your own, as this is a problem you are going to run into a lot using the molded parts that are supplied in many different kits. By measuring back - on the plans - from the front of the cowl (where the back of the prop spinner meets the cowl) to the front of F-1, I can determine how long the actual trimmed cowl needs to be. I marked this cut-off line with some masking tape. BTW...that's the Cobra motor I'm going to use sitting on the plan.

Trimming off the remaining excess plastic requires some care. If you cut too far, you can probably fix the damage, but that's lot's of needless extra work. I'm using a pair of short bladed, curved shears to snip the extra material away a bit at a time. Don't try to finish the cut tight up against the tape this way...leave some material for the next step.

The magic tool for this part of the job is my good old sanding block. This time I'm using 80-grit production paper to get a fast, clean cut without having to "scrub" at the workpiece. When I'm finished I will have sanded right up tight against the rear edge of the tape. When you are sanding along the edge of a plastic molding like this one, it's a lot easier to move the abrasive back and forth along the edge rather than across it...that would invite grabbing and tearing of the plastic.

I'm going to add a feature to this model that isn't mentioned on the plans. Because the molded plastic cowl is more flexible than the fiberglass units I got used to on my prototypes, I decided to add a backplate that functions as a reinforcement to keep the rear edge of the cowl more rigid. I'm using 1/16" aircraft plywood for this, and here you can see how I simply traced the outline of the rear cowl face onto the wood with a nice sharp pencil.

I want the plywood plate to fit inside the rear of the cowl, flush with the back edge of the plastic, so I am marking the insert to relieve the outside edge by the thickness of the cowl...about 1/32" . With that done I trimmed the plywood back to the inner line.

This is a test fit of the insert into the cowl to ensure that it goes into place without either gaps or bumps that would stretch the plastic cowl out of shape and spoil the fit with the rest of the nose structure.

With the fit of the outside edge of the insert confirmed, I marked the cut line to remove the inner portion of the plywood plate so the completed cowl will slip into place around the motor installation.

I slipped the plywood insert into place inside the cowl molding and glued it using ZAP-A-GAP. Here I have a little sanding left to do to clean up the fit. As we go on you'll see what this completed assembly should look like from the outside.

There's more going on here than meets the eye. Inside the cowl the entire motor, mount assembly, and spinner are assembled in place, held in alignment with that masking tape. Since the motor mount assembly provided in the kit mounts against the F-1 former with adhesive, I decided to use an unusual method of aligning the motor/spinner assembly with the cowl. After checking that the required thrust offset is correctly built into the back face of the motor mount and that the F-1-to-spinner distance is correct, I put a bit of slow curing epoxy onto the back face of the mount and aligned the entire assembly as you see here. By default the thrust angles are correct AND the spinner aligns perfectly with the cowl. This may seem backwards, but it works fine...think about it.

Once the epoxy that is tacking the mount assembly in place has cured, I gently remove all that tape and slip the cowl off. At this point the motor mount assembly is in exactly the right place but it is still somewhat delicately attached.

A few short strips of lightweight fiberglass cloth and some ZAP-A-GAP do a fine job of creating a reliable bond between the mount assembly and F-1. Make sure you use enough adhesive in a place like this to saturate the glass cloth thoroughly. You'll know that's happened when the weave of the cloth appears clear rather than white.

There's a good reason for having several different grades of ZAP. I want to reinforce the attachment of the motor mount to F-1 everywhere possible. Around the top radius I pressed a couple more short strips of glass cloth into place tight up against the wood, and then saturated the whole deal with thin ZAP, which wicked into every pore and crevice to turn the whole assembly into a single unit of structure. I did the same thing along the bottom side of the mount.

As soon as the ZAP hardened, I used a sanding block to clean off all the rough edges and smooth the exposed surfaces. (I also covered the Cobra motor with a bunch of masking tape while I was sanding the fiberglass.)

Here I am using a razor saw to cut openings in the reinforcing insert at the rear face of the cowl. You'll see in a moment what these are for.

The modified cowl with the backplate insert I added fits snugly against F-1, but it still needs something to hold it in place. I have added two tabs of 1/8" plywood glued to F-1 and recessed just far enough from the outer face of the fuselage side to let the cowl slip over them and fit flush. Here I'm adding reinforcement in the form of some more strips of fiberglass cloth bonded with fast ZAP

Now you can see how the cutouts I made in the cowl backplate insert are going to fit over the attachment tabs.

Now I have assembled the cowl in place, properly lined up with the rest of the fuselage and held in place with some masking tape. I previously marked the tab locations and the cowl to line up so the marks for the screw holes will center over each tab.

Drilling through the cowl wall into each of the tabs is easy.

I'm using 3/8" socket head sheet metal screws to retain the cowl. These are just long enough to reach all the way through the tabs inside without being needlessly long or heavy. I'll remove the tape once all the drilling is done and the screws are tightened in place.

This step is an easy one to forget. No matter how carefully you have lined up everything during the assembly so for, there are going to be minor misalignments bewteen the cowl and the rest of the nose structure. This is the time to get aggressive where the sanding block meets those last little imperfections...but...be sure you don't sand through any thin spots. As before, I'm using 80-grit production paper here to cut cleanly without any extra pressure.

There's one spot on the nose of the TigerKitten that may need extra attention during this final shaping with the sanding block. The lower front corners of the fuselage where they meet the cowl may insist on sticking out and creating bumps, so don't be afraid to let the sanding block show that extra wood who's in charge. There's a backup piece of structure inside here to give you a little extra something to sand on.

The last step in the job of fitting the cowl is cutting and trimming the air intake hole. I began by rough-cutting this opening with the cowl removed. Now I'm using one of my favorite shop tricks...the custom sanding tool made from whatever is at hand that fits the job, wrapped with an odd piece of the right grade of sandpaper...to clean up the outline of the air intake.

That white stuff in indeed "fiberglass"...woven glass fiber cloth. There are more categories and variations of fiberglass cloth than I can keep track of, so I manage by knowing what I need to know about the varieties that I use to build airplanes. What I'm using here is, I believe, referred to as "E" weave cloth (if somebody out there can correct me, let me know and I'll post the info) This is the stuff you'll most often find packaged for model airplane use...it's suitable for both laminating (building up molded parts) and surface coating, which is what we are doing here. This is "two ounce" cloth, which means that it weighs two ounces per sq. yard, and is just about the ideal weight for reinforcing wings and fuselages of medium sized models like this one. One of the important characteristics of E cloth is that it is really LIMP, which means that it will drape and form easily around compound curvatures even more severe than the ones formed by this wing center section structure. To get to this point I have used REALLY SHARP scissors or shears to cut the cloth enough oversize that I have plenty of margin past the edges I want to cover. You'll see why this is important. DON'T try to cut glass cloth using dull scissors or razor blade cutters... you'll end up with a frayed mess and waste a lot of good material.

For years the term "fiberglass resin" meant polyester resin, that you catalyzed with methyl ethel ketone peroxide (MEKP, which is nasty stuff) and which can be really fussy about whether it wants to cure or not over various substrates such as wood with any sort of finishing product already on it. We used it because it was (and is) very easy to sand. Until recently epoxy resins, which are far more tolerant of whatever might be underneath them beside glass cloth and balsa wood, were nasty to sand...they'd gum up, clog sandpaper, and generally frustrate you. That time is past. Choosing a good surfacing epoxy like Z-POXY Finishing Resin, which I get from Frank Tiano Enterprises ( http://www.franktiano.com/ZapFrameset-3.htm) gives you trouble free curing with easy sanding. For surface glassing jobs like this I mix the Z-POXY per the instructions and thin the mixture with 25% denatured alcohol by volume...this makes it easy to fill the weave of the cloth without tugging and slipping. Right here is where it's necessary to strike a balance... you must FILL THE WEAVE so that the cloth becomes translucent as you see here. That indicates that the glass fibers are thoroughly wetted with resin and will provide full intended strength. Any extra resin pooled on top becomes extra weight. There are various techniques around for wiping or blotting any such pooled resin away before it cures, but I've had the best luck with thinned resin brushed out carefully and left to cure.

We have to make the glass cloth lie smoothly around whatever sticks out, protrudes, or otherwise can't be temporarily removed. In this case the previously installed aileron horns are in the way. The fix is easy...cut a couple of short slits in the cloth so it will lie neatly around the horn extensions. It isn't necessary to make the edge of the cloth fit perfectly around the openings in the balsa sheet...close and neat is OK here. Do this with plenty of extra loose cloth to work with BEFORE you get any epoxy up close to what you want to work on.

The glass cloth we are using is limp enough to lie easily around compound curves,. but it is not going to fold around a sharp edge without a little help . What's happening here is that I have applied epoxy to the cloth over most of the upper center section sheet with only the aileron horn area and the aileron cutout edges left to do. You can see how I have cut the cloth right up to the edge I'll be asking it to stick to so there won 't be any folds, tucks or puckers to keep it from lying nice and flat against the balsa structure.

The next step is to stick the cloth in place along the aileron well trailing edge with a nice wet coat of my thinned epoxy mixture. Pull any overhang well past the structure you want it to cover and leave it alone until the epoxy has cured...don't fuss with edges like this while the cloth can still slip and slide and end up where you don't want it to be.

Here's the top surface of the wing center section with the glass cloth in place, stuck down, and saturated with my thinned ZAP finishing epoxy everywhere I want it to become part of the finished airplane structure. When it's cured I'll trim those overhangs away and we'll move on to the bottom surface.

On an inside edge like this the best way to trim the overhang is with a new/sharp blade, and it will work best if you use a slicing motion rather than trying to push the blade through the glass cloth. I'll trim the outside edges after finishing this cut.

Once the epoxy has cured on the top surface and all the overhanging edges of epoxy-saturated glass cloth have been trimmed, it's time to do the other side. Here I'm using the same wet brushing technique to be sure the epoxy fills the weave of the cloth. In the case of this airplane the upper surface of the wing presents the most complex part of the job... getting this bottom section covered is just a matter of getting the glass cloth smoothed out and thoroughly wetted.

Remember, you can't force the glass cloth to fit around or into tight corners without puckering or wrinkling. Where the bottom covering wraps around the leading edge and up toward the top of the wing, the leading edge attachment dowels are in the way. I cut slots to permit the cloth to lie flat around them...the excess will get trimmed away after the epoxy cures.

The TigerKitten design calls for two aileron servo cutouts in the top center section. I chose to make these after the structure was already glassed. Here you can see how I have laid masking tape over the area to be cut out and used that as a surface that is easy to mark with a pencil to lay out cut lines. I'm cutting aileron mounting rails that will slip into those "T" openings from a piece of 1/4" x 3/8" spruce, which you can see at the top. One insert has already been cut.

There is another way to attach glass cloth to the airplane structure. In this case I wanted to reinforce the aileron servo cutout area after fitting the servos, so I cut a small piece of that same 2 ounce cloth just big enough to cover the area I was concerned about. For this little extra section of "glassing" I did not want to mix up more epoxy, so I used a simpler method that works fine for small jobs.

Thin (fast) ZAP will wick into a piece of fiberglass that is placed smoothly against a surface like this one and bond the cloth into place almost instantly. The drawback to using this method is that the cyanoacrylate adhesive does not provide much of a sanding base for getting a smooth finish on the glass weave, and using ZAP in this way except for small, quick tasks would be a very expensive way to employ it.

You can see where the thin ZAP has wicked past the edges of the structure out into the weave of the glass cloth. It happens that this makes the glass easy to trim, just as it would have been if I had used epoxy. I'll clean up these servo mounts with my No. 11 blade and then set this part of the job aside until it's time to do some covering.

Every bit of structure that will part of the surface of the finished airplane...this includes everything that serves as a support to fabric covering... must be sanded absolutely flat and true or it will show up as BAD CRAFTSMANSHIP on the finished airplane. These stringers and the upper and lower longeron caps on the rear fuselage are an excellent example of places that are easy to forget about until it's too late. I'm using 80-grit production paper on my favorite LONG sanding block to dress off the outer surfaces of all these components so that the covering will lie dead flat across them. We're going to be adding the tail surfaces shortly and it is a lot easier to do this particular sanding job now than to work around extra structure.

With all the surface sanding on the fuselage done, it's time to go ahead and install the horizontal stabilizer. The incidence angle (which happens to be zero degrees) is determined by the rear portion of the upper longeron,and if you have built everything straight and true so far, this is a default setting. Alignment is the critical deal here. I have pinned the fuselage assembly in place over the plan in order to make the drawing of the stabilizer relative to the fuselage valid as an alignment reference. If the fuselage is set up square on the board, and the stabilizer is squared off as I have it here, everything will be where it belongs. What you can't see in this shot is that I have already used a ruler to check that the distance of each stab tip off the board is tha same. With a couple of pins and a final check, a generous shot of thin ZAP locks the assembly in place.

After the horizontal stabilizer goes in, the vertical tail (the fin) is next. I squared that assembly up just the same way before glueing anything. What comes next is this little balsa sheet covering base, which is necessary because we're going to cover the entire fuselage side and fin together to create what is called a fabric fillet. In order to make this work we need a piece of structure that will function as if it were part of the fuselage side, to serve as a covering attachment base.

This is the covering base insert in place. I have tapered it to fit smoothly against the vertical fin trailing edge and sanded it to blend with the contour defined by the fin, the top longeron, and the stringers. When we get to the covering job you'll see exactly why we need this insert and how it functions.

The main landing gear base plate (F-2) is backed up on the inside by a couple of reinforcing blocks. I have drilled through F-2 and the blocks and am using a 10-32 tap to cut threads for 10-32 nylon bolts that will hold the landing gear in place. Rather than use blind nuts, which can pull loose and rattle around inside the airplane when you want to work on it, I reinforced these threads with thin ZAP and re-tapped them to provide a secure attachment.

This is the pre-formed landing gear held in place with two hex-head 10-32 x 2" nylon wing bolts (DuBro Cat. No. 164) When you are mounting the landing gear be sure that the taper in the legs, as seen from the side, appears to sweep TO THE REAR, not to the front. I meant it to be that way. This puts the main axles closer to the leading edge of the wing, with the result that the airplane is less likely to swerve under power on takeoff and also less likely to bounce on landing if you come in a bit too fast.

Here I have drilled each leg of the landing gear for installation of a pair of DuBro axle shafts (No. 247) . In order to get a dependable, secure mounting base for the wheel pants I elected to add a rectangular bracket about 1.5" long to each axle. I cut these from some scrap .030" aluminum sheet I had lying around. G-10 epoxy board or even good quality 1/16" plywood would also work. The brackets are trapped between the axle shaft assembly and the gear leg...when the wheel pants are ready to mount I will drill screw holes in each to match the openings already in the plates.

This is the left main gear leg with the wheel pant mounting bracket as seen from the outside. The broad hex nut fitting is part of the axle assembly.

With the landing gear temporarily installed, my next job was to cut, fit and glue the 1/8" balsa sheet on the chin (the lower front cowl) Note that this balsa is fitted with the grain running across the fuselage for extra stiffness.

F-10 is a laser cut 1/4" balsa sheet filler/spacer that forms the forward portion of the fairing between the landing gear mount and the bottom of the wing. Here you can see that I have trimmed and beveled it to rest squarely against F-3 and fit the curvature of the wing leading edge.

Both F-9's get trimmed as necesssary to fill out the base of the fairing and provide a solid glueing base for the balsa sheet surface.

With the wing removed from the fuselage we get a clear shot at sanding the F-9/F-10 assembly to permit the outer sheet to fit tight against the wing surface.

I used a piece of 1/8" balsa sheet sanded to a taper under the rear edge to allow it to fit snugly against the wing center sheeting. I used ZAP A GAP for this assembly because the slower setting speed gave me time to press the outer sheet firmly into place.

I have used masking tape all around the outer edges of the fairing to protect the wing center section skin as I use the sanding block with 80-grit paper to smooth and radius the fairing assembly.

I used a semi circular balsa sheet insert to provide some reinforcement along with a smooth transition for the fabric covering where the underside of the wing trailing edge meets the rear fuselage. This will probably be presented as a laser cut part in the production version of the kit.

I'm back to the sanding block to radius the edges of the insert assembly AND to blend the bottom surface of the sheet into the bottom of the longerons.

This is the front/top deck assembly all shaped and sanded, in place on the fuselage and ready for the nose cowl to be fitted.

The top deck is really a removeable upper front fuselage. It provides excellent access to your battery pack as well as to whatever components of the radio system you choose to mount on the upper side of the inner tray. It's big enough and important enought that a good fit and a neat appearance really matter. Premier has made the job of building it quite a bit easier by providing a laser cut base/outline to which everything else gets glued. I began assembly by gluing the 1/8" x 3/16" balsa base strips along either side of the ply base plate. These lie flush with the outer edge of the plywood, and must be bent gently to follow the curve at the front end of the base plate. For this part of the assembly I am leaving everything pinned to the building board, nice and flat.

I chose to begin laying out the first fuselage side frame by positioning the laser cut balsa wing saddle and landing gear mount reinforcement. These two parts are positioned in reference to a 3/16" sq. balsa upright which I have fitted in place here. Thin (instant) ZAP is the adhesive of choice here as it allows me to locate and pin each of the parts involved in exactly the position I want, then add adhesive.

Here I have fitted the top longeron to the 3/16" sq. balsa upright that supports F-1, as well as the 1/8" x 3/16" balsa diagonal brace that lies directly behind it. This is an example of the way you should make all the joints in a model structure fit... it doesn't make sense to have the advantage of precision laser cut shaped parts and not have the joints you fit yourself match that level of accuracy.

I have all the longerons, uprights, and diagonal braces in place along with the laser cut components...this defines the structure of the side frame.

The basic fuselage structure consists of two identical side frames connected by various cross members and formers. The best way to to be sure both of the side frames are actually identical is to build one directly over the other. That's what's going on here. I have completed the first side, sanded the structure smooth with the good old sanding block, and covered it with a new sheet of plastic wrap while it is still in place on the plan. (It will be necessary to move and reset the pins that are holding everything in place, and then insert new pins as necessary to hold the new/top parts as they are assembled.) Here I have the laser cut wing saddle in place to begin constructing side two.

Here's another quick look at the way the various 3/16" sq. balsa longerons, uprights, and diagonals are going to fit against the wing saddle as I build side two in place over the first side frame.

The trick to building really accurate fuselage side frames is block sand them aggressively while they are still pinned to the building board. Here I am using 80-grit production paper, which is coarse enough to cut through all the hard spots of glue neatly without compressing the balsa. The important thing here is to sand off enough material to get a flat, true surface. Don't leave ridges or low spots. Here I'm sanding the second side, still in place. When it's done I'll remove it along with the top sheet of plastic wrap and repeat the operation with the first side.

A 1/64" plywood doubler is added to the inside face of each of the side frames before we go any further. These will be laser cut parts in production kits, so I have not gone into detail on making them. I used ZAP A GAP for this operation to give me time to spread an even layer of adhesive over every part of the side frame that is going to contact the doubler.

The side frames are assembled upside down over the plan in order to take advantage of the flat, straight top longeron as a reference to keep the rest of the structure square. This is the left side as seen from what will become the inside of the fuselage. I'm using an actual drafting square to get the alignment right at this stage before I proceed further. The side frame is pinned through the top longeron to the building board in several places.

I have added the laser cut plywood landing gear mounting plate and the rear wing mounting bolt plate ( F-2 and F-6) as well as the 3/16" sq. balsa crossmembers that correspond to their positions between the top longerons.This is probably the most critical part of the fuselage construction where correct alignment is concerned.

Here's another look at the basic fuselage framework all squared up and glued back to the wing trailing edge station. Notice that I have not yet made any attempt to pull the sides together at the tail.

Got it right! I'm double checking that the fuselage side frames are assembled square to each other and the building board (which is my reference for all alignment) before I move to the tail.

The vertical members at rearmost point of the fuselage are 3/16" sq. balsa. When they are drawn together and glued, they will have to match the width of a 1/4" thick rudder. It's necessary to bevel the inside face of each one so the final outside dimension will be 1/4" , not 3/8". I'm using an 80-grit sanding block for this, with the assembly still flat on the building board.

The rearmost uprights of the fuselage side frames form what is also referred to as the tailpost. In the last step I beveled them to match the 1/4" rudder leading edge. Now I'm using clothespin clamps to hold them in exactly the right position while I use fast ZAP to glue the joint.

All the fuselage crossmembers are 3/16" sq. balsa. Cut them in matched pairs to align the side frames with the plan. They all get the same ZAP treatment once they are in place.

Check the assembly AGAIN to be sure it's square. If you make a mistake in alignment here, it gets harder to fix with each successive step you complete.

I'm using a bubble level to be certain the fuselage frame is squared off before I go on to work on the the wing attachment structure.

Prior to positioning the wing on the fuselage assembly I measured and marked a centerline equidistant from each tip. I also marked a center point on the leading and trailing edge station formers. With those matched up, I used the long metal straightedge as an aid in setting the wing at exactly a right angle to the fuselage.

I'm using an older model Robart incidence meter to check that the wing is set at an angle of three degrees positive. Remember that the entire airplane is assembled upside down, so the meter will read out at a negative value.

I used the pre-drilled holes in F-3 to mark the wing leading edge at the center and drill holes for the 1/4" dowel mounting pegs. These extend all the way back to the main spar doubler and must be glued securely. I used ZAP A GAP applied to the inside of the opening before inserting each dowel.

Here's a look at the inside of the nose structure so far. I have added pieces of 3/8" quarter-round balsa as corner gussets along the back of F-1

The formers that create the raised portion of the rear fuselage (the "turtleback") are added now. I am using a square to make sure F-7 is perpendicular to the top longerons.

This is a better look at F-7 through F-11 in place.

The top stringer is a piece of 3/16" sq. balsa, which is intended to lie straight as seen from the side. I'm using a steel ruler to check ...this is where you need to trim the top of one or another of the formers if necessary to keep the stringer from bowing or bending.

The top stringer is glued in place. It ends flush with the rear face of F-11.

The top center rear deck stringer is 3/16" sq. balsa. All those on the sides are 1/8" x 3/16" balsa, and it's best to add them one at a time, alternating from one side to the other to minimize the chance of pulling a twist into the structure. I used fast ZAP here, holding the stringers in contact with each former in turn to get the alignment exactly right.

The best way to locate the position of the side stringer is to measure off the plan and mark a location where the stringer crosses each upright in turn.

The fuselage side stringers rest on the top of each of the uprights, but are recessed to lie flush with the tailpost.

All the rear deck stringers are in place now.

Here the left side stringer has been installed, using the locating marks I made earlier.

The surface created by the longerons, F-1 former, and the side stringer must be sanded to provide a mounting base for the side sheeting that comes next. Notice that the surface is not flat...the stringer creates a bulge that will cause the sheet to assume a shallow convex curve.

The fuselage side sheet is a complex part that was not laser cut in my early kit. I'm not sure how this will be presented in production kits, so I'll show you how to mark and cut it yourself. I cut a piece of 1/16" balsa sheet from a 1/16" x 4" x 36" sheet long enough to extend from F-1 to the rearmost point on the side sheet. Here I am using the top edge (along the top longeron) as a reference, as it provides the only straight line I can use as a starting point. I have used clothespins as clamps to hold the top edge of the sheet to the longeron.

With the clamped-up assembly turned over I can mark the cutting line along the wing saddle and the rest of the bottom edge of the fuselage onto the side sheet blank.

Without cutting the plan it's hard to mark that inside cutout curve onto the sheet blank. I traced the curve off the plan onto a sheet of ordinary copy paper (you can see through it OK if it's held tight against the plan), then cut out the pattern. Here I am tracing the resulting curve pattern onto the side sheet.

This is the side sheet blank with the inside curve marked, ready to cut, resting in place on the fuselage side where I'll ZAP it pretty soon.

This side sheet is going to have to assume a gentle compound curve to fit tightly against all the underlying structure. The easiest way to get a sheet of balsa to do this is to wet it with a light spray of water ...only on what you want to be the outside surface of the bend. The sheet will automatically curl away from the wetness AND become more pliable at the same time.

ZAP A GAP is my adhesive of choice here, as it allows me to spread an even layer of glue over all of the longeron, former and stringer surfaces where the sheet is going to stick.

It's easy to press the wet sheet into place all around the edges where you want it to stick using the palm of your hand. ZAP A GAP will grab and hold a joint like this in ten seconds or so.

There are lots of places in the TigerKitten fuselage assembly sequence where the edge of a part may not seem to fit right away. Don't sweat that...it's all planned to come out right. Here the best way to blend the rear point of the side sheet into the rest of the structure was to design in a longeron cap of 1/16" x 3/16" balsa, which you see being fitted here.

One of the features that gives the 'Kitten such a finished look is these stringer inserts, which are provided laser cut slightly oversize to permit you to trim and bevel each one for a perfect fit between each pair of stringers after YOU have assembled them. You can see where a bevel needs to be sanded into this one.

I have sanded a bevel into each of the edges of the insert that will fit against the two adjacent stringers...you can see how it's going to slip right into place.

I left just enough material on this insert to give a tight press fit...now thin ZAP is the perfect adhesive to keep it there. All the rest of the stringer inserts go in just the same.

All the stringer inserts are in. You can see that the material selected for them leaves some extra thickness to be sanded away, allowing a perfect fit.

Here's what the inserts should look like when you have the entire surface of the assembly sanded.