13th January 2013 - Left wing top skin

The wiring is in, the inspection hatch is in, the plumbing for the pitot is in, the remote compass is in, and the inside of the wing is fully sealed with epoxy varnish. I hope I haven't forgotten anything because today with the essential help of my friend Paul (the fastest stapler in the west) the top skin was glued onto the left wing. It simply isn't possible to apply the glue fast enough with just one person before it starts to gel in the pot. The glue was the usual mix of West system epoxy with the 206 slow hardener and a 6% addition of microfibres. This was spread over the ribs, spars, and leading and trailing edges of the wing structure and then onto the wing skin completely filling the gaps left in the varnish by the masking. Actually the latter statement is not exactly correct. Applying the Randolph EV-400 epoxy varnish thinned to soak into the wood also resulted in it soaking straight through the masking tape and varnishing the protected areas almost as though the tape wasn't there! Still I enjoyed the hour spent sanding it off where it shouldn't have been in the first place. Note for next time use a plastic tape.
The glue can now set overnight before I remove the clamps but even with them and the nailing strips in place the aerofoil already looks superb. It is no wonder the Tailwind is so fast with such an elegant thin section wing.

11th January 2013 - Left wing plumbing and wiring

The final job on the wing before gluing on the top skin was to install all necessary plumbing, wiring, and components. This comprises the tubing to the pitot, the remote compass and its wiring, and the cables for the wingtip strobe and navigation light. 5/8" holes were drilled through the three sheeted ribs to take SB625-8 plastic bushes. The holes in the inboard rib were positioned so the wires and tubing will pass directly into the rear spar cover and connect to the wiring in the fuselage. The wiring to the remote compass was kept separate from the strobe wiring to ensure that no interference would take place. Wires were secured to the lower skin using self-adhesive cable tie bases and were protected as they pass over the ribs using spiral wrap.
The second picture shows the pitot mount with the pitot installed. The mount is screwed to the back of the spar with 1/2" stainless steel #8 screws and glued to the lower wing skin with a slurry of epoxy mixed with microballoons. This provides a light but stiff seal between the shape of the lower skin and the straight bottom plate on the pitot mount. As the picture shows it will be easy to check both the pitot and the strut attach as well as the general condition of the inside of the wing through the access panel.

7th January 2013 - Sealing the inside of the left wing

I hate painting! probably because I'm so bad at it but it has to be done. Yesterday and today I gave two coats of Randolph Epoxy Varnish EV-400 to the inside of the left wing. The first coat is thinned about 50% to ensure it soaks into the wood. It is important to keep the surfaces to be glued free of varnish so the top surfaces of the wing ribs and spars were not varnished.
The varnish takes about 7 days to fully set and then is impervious to pretty much everything.
The top surface of the wing is still to be glued on and of course can't be painted when it is in position. It was first rough cut from one of the scarf jointed lengths of 3/32" mahogony ply  then masked off  to match the ribs and spars. The glue will be spread to fill the gaps in the varnish.
Next job is to fit out the internal components in the wing: the remote compass, the pitot, and the wiring for the nav and strobe lights, then it is a case of varnishing the inside of the top surface and gluing it on.

3rd January 2013 - Under wing access panels

It is inevitable that at some time access will be required to the inside of the wings so I decided to install an access panel in the underside of each wing just behind the strut attach bracket. In the left wing, this will also give access to the pitot connections.
I used the CNC router to cut out two 60mm radius disks out of 3/32" aluminium with six holes spaced radially on a 55mm circle. These will form the access panels. Then two rings were cut with matching holes and a centre 50mm radius hole and outside diameter of 140mm. Next a 120mm diameter hole was cut in the wingskin using a flycutter and a cutout for the pitot mount was also made. The mounting rings were then drilled for 6 platenuts which were flush riveted into place. The access panels were countersunk to take #8 screws. One ring was then bonded to the inside of the left wing and clamped into place for the epoxy to set.