February saw us continuing with the construction of the fuselage skin panels and the creation of fiberglass wing-root fairings. These were built by attaching the lower wings and making a very rough sub-frame to support the fillet using blue foam and scrap plywood. The wooden sheeting in the wing root area was first covered with a layer of duct tape in order to protect it, then modeling clay (many pounds of it) was applied to shape the fillet. The clay is much easier to work after microwaving... about 3 minutes on "high" seemed about right for a hand-sized block of clay.
After applying clay and rough sculpting, we formed the right shape... a bit longer and it was all smoothed out. When it was "just right", we applied layers of fiberglass cloth over the clay to build up the prototype wing fairing and subsequent mold form. This not only covers the wing root area, but extends forward as well to fair in the area where the landing gear leg meets the fuselage.
After the epoxy cured, we removed the fiberglass, cleaned up the edges, sanded it a bit, and were pleased with the results. The fairing is attached to the fuselage via quick-release fasteners, which are anchored to the aluminum side formers. We then carefully trimmed the hinged aluminum side panels to overlap the fairings over an aluminum angle stiffener.
On the inside of the cockpit, we installed small aluminum panels to cover the wing root area. It will be easy to get into this area when needed for inspection, but most of the time you won't want or need to see it.
The lower edges of the side panels anchor to the fiberglass fillet using camlocks, while the edges of the panels anchor to the aluminum fuselage formers using the same type of fittings. The fiberglass and interior pieces also anchor to the formers in the same way. In most areas, there is a sandwich with the side panel and faring being held with a common connector.
In the end, we have achieved the goal of easy maintenance access, ease of construction, and low weight, while also making for a neat and attractive installation.
The design allows the panels and fairings to be factory supplied with final trim on two sides done at installation. The sheet metal is one of the more labor intensive areas of construction, and we aim to greatly reduce this effort for builders.
In February we also began the process of building the upper wings. These are nearly identical to the lower wings; they differ in hardware and a few details. We have also been working on the layout of the upper wing center section, building a quick mockup with pine spars to ensure that the wing fuel tank and fittings all work out as expected.
As this is written (mid March) we're only a month away from Sun N Fun 2004. We will have the Model 14 prototype there, of course.
We are trying to make as much progress as possible, though the days before SNF are hectic to say the least. We pack up all sorts of displays, our tents, and get set up so that most of the company plus family members can camp comfortably in Lakeland for a week and a half... no small undertaking.
As we're fond of telling people, the prototype will be done on Tuesday - we leave the question of which Tuesday a bit open to speculation.