Chapter 5 - Fuselage Sides
In chapter 5, the sides of the fuselage are constructed. Simple jigs are constructed to permit the curved shape to be easily formed, and to form wooden longerons into the proper curvature. Then the foam and inside layups are done.
The Jigs
The jigs for the fuselage sides consist of 1" thick pine boards cut to shape that the upper longerons are formed against. These are then set upright and a thin wood panel (masonite in the plans) set atop a pair of the pine jigs to provide the curvature of the fuselage side itself. Simple enough.
The pine boards should be wide enough to permit the curvature required to be cut into it. The supplier I used didn't have any wide enough, only some almost wide enough. So I bought those. I would need to glue off-cuts from the inside part of the curve onto the ends to provide the width for the complete curvature to the ends.

As my fuselage shape is a little different to plans, the plans dimensions could not be used. Having my planned fuselage drawn in CAD, it was simple enough to generate the dimensions needed, however. I printed the required dimensions and drew them onto the pine boards. I marked lines at 5cm intervals along the length of the boards, then marked up each line how deep the cut was needed. Then I just joined the intersections to create a gently stepped curve along the length.
I ignored the ends initially, as I hadn't added the extra width yet. I cut the part of the curve that fit in the existing width of the boards, then used parts of those off-cuts to widen the ends, then marked and cut those as well.
The plans have the jigs make in 3 segments for each of the 4 parts of this jig. I made mine in continuous lengths. Part of the reason for this is the plans specify using a spacer to increase the curvature slightly when forming the longerons, as bing on the inside of the foam sides, the curve is slightly tighter. I calculated the extra curvature required using the CAD drawings, and found it to be <2mm along the entire length! Thus I elected not to make the jigs in segments and increase the curvature. I'm pretty confident I can bend the longerons 2mm along their length when fitting.

Once the four boards were cut (two for top, two for bottom of the sides), I clamped the matching pairs together and sanded them to a near perfect match. Any inconsistency here probably isn't significant in the end, but I am being particular to create a nice symmetrical fuselage!


The Longerons, Doublers, and Stiffeners.
The plans call for spruce to be used to create the wooden longerons and stiffeners, as well as a few other small parts. Spruce is not generally available in New Zealand, but I found an aircraft supply company that imported it to order. The quantity needed for this aircraft is relatively small, especially compared to aircraft with entirely wooden airframes! I got a quote, that included savings in shipping resulting from combining with a larger order from a wooden aircraft builder. I was shocked at the price quoted! Surely there was a better way!
Builders in non-US countries have used some alternative wood over the years in building these aircraft. Hoop pine is one example. I couldn't find a source of that, either. So I found the characteristics or spruce and compared with other wood that was available in NZ.  What I found was gaboon, a wood from west Africa that has similar strength and density to spruce. The catch is, it's not sold here in convenient strips and sizes for aircraft building, but it is readily available as an exotic plywood. I ordered a sheet, 6mm (1/4") thick, 5-ply.  The plans call for a thickness of 18mm (3/4"), so I can simply laminate 3 layers together to obtain the desired thickness. In fact, in order to create the curvature for the upper longerons, the plans call for 3 layers of 1/4" spruce to be laminated into the curve. I am doing the same thing, except each layer is already 5 plies! So these wooden parts are ending up as 15-ply pieces, and seem plenty tough and light.

Another catch is that the sheet of ply is shorter that the length of the longerons. Is is strong enough and permissible to join pieces to create the length required?

I searched the e-mail list archives for information. I found what I needed. Nat Puffer had discussed with a builder what to do after they inadvertently snapped a longeron. He advised that the longerons are not primary structure, but rather help form the desired shape of the fuselage and provide a hard point for attachments, such as canopy hinges. He advised that a simple scarf joint would be fine for the repair.
I found a builder's page who had done just such a repair. He had also tested a joined piece (of spruce) and a continuous piece of the same dimensions and found that the continuous piece failed before the repair one. So plenty of strength here in either case.
Since I am laminating 3 layers together in forming the longerons anyway, I can alternate the ends so that joins are not adjacent to each other, forming lap joints. I also cut the ends at 45deg where they join together. Not great for a scarf joint, but should be more than adequate with the effective lap joint as well.

I generated LOTS of sawdust cutting strips off the plywood sheet. Most of the strips are 1" wide. I used my circular saw (with a 40-tooth blade) attached to a home-made guide rail to ensure straight consistent cuts as the desired width.

For pieces that were to join end-to-end (to create the length required for the longerons), I then cut 45deg angles on the ends, though the 6mm thickness. In hindsight, cutting 45s along the length would have made a wider join that would have been easier to handle. Oh well, it's good enough.

I mixed up a batch of epoxy mixed with colloidal silica to thicken it to a thin paste. Pure epoxy at 30c would have been very thin indeed (helps it to wet-out well!) and would not have readily bridged any small gaps or voids in the joins.
I butted the extensions to the longerons together with epoxy applied to both sides, then carefully placed a thick MDF panel on top, followed by some weight to ensure nothing moved and that it was kept flat.
I then took all the smaller pieces for doublers, stiffeners, etc. and applied a thin layer to both sides that were to be laminated, then pressed them together and adjusted each layer to be properly in-line. Then another piece of MDF was laid on top of this collection of pieces, and more weights on top, to ensure all layers were kept pressed firmly together until cured.

After an overnight cure, all appeared well. the longeron extensions stay together fine (though they'll be a lot stronger when the layers are laminated together), and the smaller pieces are tough and light with no sign of any weakness between layers (nor should there be). The laminated layers had shifted horizontally slightly in a few cases, but the edges cleaned up flat with a little bit of sanding.

Laminating the longerons was straightforward enough. I painted epoxy (thickened to a runny paste with colloidal silica) on both sides to be bonded, then pressed the two sides together. 3 layers for each longeron. Once both longerons were laminated together, they were clamped to the jigs to cure. They spent the night in the heat tent (which I might simply refer to as the 'autoclave' from now on, despite the fact that is quite an exaggeration). 
The result is quite good. There is a slight offset vertically between layers, which a little sanding mostly smoothed out (without removing excessive material, of course). The curve is fine, though it does spring back a little. There is enough flex that there is zero concern about bonding it at the correct curvature to the sides.


The 5' stiffner was constructed in much the same way, curing against the jig in the appropriate location to form the desired curvature without the need for saw cuts etc.
The doublers (fore and aft) are on parts of the longeron that are almost straight anyway (aft) or are short enough for the curvature to be insignificant (fore). 
I attached the stiffener and doublers all at once, screwing the stiffner and forward doubler onto the longeron (haveing pre-drilled holes of course), and clamping the aft doublers to the sides. Again, no problem. I added a bit of epoxy paste (colloidal silica mix) to smooth the transition where the fore doubler and stiffeners meet the longeron. Just a tiny bit. I also filled the screw holes later with epoxy paste. Probably left small voids inside at the deepest penetration of the screws, but I don't foresee this being any problem.

Al also rounded off the inside corner (where the occupants may bump against it in flight, and where glass will soon have to conform to). I used my (new) router for this, with a 6mm (1/4") rounding bit. Worked very well, except where the stiffeners and doublers join. I actually made a bit of a mess of the forward portion of one of the fore doublers when the router tipped a bit off the end. Most or all of that will be trimmed off later, anyway. A few other spots that were a bit rough got a bit of epoxy paste to make the curvature consistent, as did the inside corner where the tapered part of the aft doubler meets the longeron that would otherwise be a square corner that would become an air void under glass later.


The lower longerons are to be triangular section, so I formed them in exactly the same way as the upper longerons (but on the bottom side jigs) and will cut them in half along their length with the bandsaw to create the triangular section. That should be 'fun'! This way they are already curved appropriately in one axis, so I should only need a few saw-cuts in one axis to form the vertical curve.
I had almost no vertical misalignment this time, being more careful than before (should have formed the lower longerons first? ;-) ). However, I had a few small gaps between layers in a few places, a couple several centimeters long. After the initial cure, I filled these with a runny epoxy paste. You'll never know, they'll just be a gram or three heavier.

I spent a couple of hours sanding imperfections, rounding spots the router could not reach, etc. I'd rather sand off imperfections where practical, rather than fill, as it's lighter. Watch the grams, and the kilograms will take care of themselves.

Blood, sweat, and tears - Check!

I completed the lower longerons more easily than I expected. Running the square section through the bandsaw on a 45deg cut output the triangular, curved section just as I had hoped, with minimal waviness. Great! I was pleasantly surprised and how well they turned out. I can even use the aft end of the off-cut section as the doubler.

With these complete, it was time to change the longeron jigs into full side jigs. For this, I have used thin MDF sheets that I acquired for free while pricing the plans specified masonite. It isn't quite as stiff (I added a couple of stiffeners in critical places to compensate), but it was free! They are used as cover sheets for the more valuable sheets that are sold, and apparently, have no value once the products are removed from their packaging. 
I cut the MDF sheets to the specified shape (adding my 6" extension in the middle), and clamped the two together for final sanding to shape to ensure the two sides were perfect matches.
Using the now perfectly shaped MDF sheets as guides, I cut the foam for the sides. The sheets of foam I obtained are larger than those obtained from Aircraft Spruce, so I was able to cut the sides as single pieces.

I joined the curved jigs at the ends with off-cuts from the original boards, and screwed the MDF sheets down on top after counter-sinking the holes.
The plans call for Last-a-Foam to form the raised edges of the fuselage sides; I don't have this, so I used PVC for this as well. The Last-a-Foam probably cuts and sands into angled pieces easier than PVC. I say this because the PVC is tricky to shape in this way. 
The first pieces were not very satisfactory. I had cut them with a hacksaw and sanded a bit, but they were very wavy and inconsistent. I decided to try a different method to improve the quality (I have -hopefully- enough foam for this, as I was only able to buy full sheets, so have some excess).

I took a reciprocating saw with a fine blade and tried cutting with that. It started well, then the blade caught in the foam, causing the tool itself to reciprocate instead, and as it did so, it hammered one of my fingertips between my workbench and the base of the tool. It probably happened for less than a second, but I don't know how many times my finger got hammered in that time. I do know that it hurt quickly, and a LOT, and I couldn't immediately see what damage was done due to the amount of blood. I was slightly relieved to discover with closer examination that my fingertip was in fact, still there. After attempting for a minute to wash off the blood (ineffective as it was still bleeding quite a bit, from the edge of the fingernail and the side of the finger itself on the opposite side) my wife suggested I lay down, as I was becoming faint. I did, for a couple of hours, by which time I was feeling better, though still sore. I was able to move it a bit, so was confident nothing was broken. It was sore and sensitive for some time, but returned to feeling almost completely normal after a couple of months.

I got almost nothing done on the project for a couple of months, on account of moving house, having to do some work on our car and selling it (and delivering it to the new owners 7hrs away, and flying commercial home), setting up the new workshop, and being very busy with work - that thing you have to do to pay for food and epoxy.

Back to the important business

Once my workshop was back in order, I had to make some minor repairs to my heat tent, as a leg had been broken during the move (it is made of chipboard strips after all!) and there was some other more minor damage. I reinforced the weak areas a bit too, so it shouldn't be an issue doing forward. I know now that I've said that, that a piece is going to snap at a very inopportune time...
I also took the opportunity to ensure my workbench was properly leveled when I set it up in the new workshop. I found a pack of shims at a hardware store in various thicknesses, so I added them as needed at the legs to get it as level as possible.

The lighting in the new workshop isn't anything like as good as the previous one, so I added some LED strips to fill in some darker areas; there should be adequate light to see layups clearly now, as well as on other bench areas.
Time to bring back the foam! I took the side foam and placed it flat on the work table. I have an extra step here. I routed a groove for the rudder cable conduit to be embedded in the foam. I marked the location where the rudder cable conduit is supposed to go (usually on the outside of the layup, under the armrests) and routed a groove the same depth as the nylaflow tubing is thick. The groove runs from just ahead of the instrument panel, along the sides, then ends inside the electrical channel, so that the cable will exit the firewall in the plans location.
You can see the grooves after I initially routed them in the image to the left. Not perfectly straight, so I used a piece of sandpaper and a mixing stick to smooth the ridges, allowing the tubing to run straight through.
This isn't a wholly original idea.
JD of Infinity Aerospace has suggested this, though his method is, I believe, to create a space for the tubing after the inside layups by inserting something in from the end under the glass. From what I understand that probably would work well, on a straight-sided Long-Ez. For the curved-sided cozy, not so much. So I am doing it this way. It will be fiddly getting the glass down and the tubing up through it during the layup, but since I'm hard-shelling and can position all the glass dry, it should be manageable. Read on to find out.

I attached the foam to the jigs using drywall screws from beneath, along the edges. No bondo or anything to tear out chunks of foam when removing from the jigs, and the small holes that are created are mostly in areas that get removed during contouring of the outside later anyway.

I used the router to create the control stick depressions as well and sanded the edges smooth and rounded. Easy enough. Much of this area will probably be removed as an opening into the extended strakes, but I figured there was little downside in doing it anyway, just in case the strake opening isn't enough, or something I haven't predicted is encountered.

Then I began microing the foam contours onto the sides. For the large pieces around the electrical channel and spar, I made a mistake, cutting the foam short on the front, not allowing for the taper at the top. So I had to cut triangles and micro them in place to complete this shape. Ah well, a few grams gained perhaps - but it's part of the beauty of this sort of construction than an error like this is so easily remedied.

I held all the pieces in place with drywall screws while the micro cured. This also has the advantage that the thrust from the screw when driven in pulls the pieces tightly together, which is especially useful where the pieces are flat and need to be installed onto a curved surface.


I cut nylaflow tubing for the rudder cable conduits slightly long on each end - easy enough to trim the excess later. I laid a bead of micro in the grooves before bedding in the tubing itself. Naturally, the tubing didn't want to lay in nicely, it had been shipped and stored coiled up. So I placed a strip of plastic over it then placed pieces of wood to hold it in place until the micro cured. I placed extra weights on to be sure it didn't move at all.
I erected the heat tent to ensure a good cure of the micro overnight. I didn't want the nylaflow to shift or otherwise get out of place if the micro wasn't sufficiently cured when the weights were removed. It was also the first use of the heat tent since the repairs and in the new workshop. No issues, other than taping a patch on a small tear in the plastic.
I had re-cut the pieces to form the contour after getting setup in the new workshop. Being extra careful to not crush another finger, I had rough cut the pieces with the reciprocating saw (but a different, coarser blade), then sanded them down to the desired angle and dimensions on the bench sander. To facilitate this, I divided the pieces into segments less than a meter long. It worked, but it meant that once the pieces were microed in place, there were slight discontinuities where some of the pieces met. I sanded them even with sanding blocks and loose sandpaper. To ensure I didn't gouge or otherwise damage the foam that was good (like the main piece they were microed to!) I applied duct tape (and then masking and plastic tape when that ran out) over the areas to be preserved from the sandpaper. That worked well. I did the same to protect the foam around the now buried rudder cable conduits when I sanded the micro flush there.


Following this, I began to hard-shell the foam (fill the exposed open 'bubbles with micro and leave to cure hard). I did this in two sessions using nice, dry micro to minimize weight. That's a lot of area to cover, and it took several hours to fill to my satisfaction. 
In fact, you can roughly determine the amount of time I have spent working on actual aircraft parts (not the workshop setup or heat tent repairs) by taking the amount of time it takes to listen to the audiobook
"Ready Player One" by Ernest Cline , plus about 2 hours. I believe I am more productive with another part of my brain engaged listening to something, well, engaging like that. Another plus, was that book really draws you in and as a lot of intense periods, so I kept labouring away when I might otherwise have stopped for a break - can't stop now, the book is too interesting!! I highly recommend reading it some time. Now I need to find something else to listen to. Oh, there's a sequel being written! And a movie adaption by Spielberg! Excellent!