The main advantage of using ebechi to cover the wing cores is that it makes it easier to get rid of any uneven parts. These usually occur on the underside of the wing where the main spar or the two spars on either side of the hinges of the control surfaces are epoxied into the foam. The 0.6mm thick abachi usually gives enough “margin” to sand the uneven bits out.
Sanding the ebechi is a messy job. I usually do this outside and was lucky that today was relatively warm and windy. To sand the ebechi I use my favourite Permagrit (the really rough side), my trusted old bosch sanding machine (80 grit sandpaper) as well as a block with 100 grit sandpaper. Most important is to sand the leading edge of the wings into shape. During the building I put a few mm of resin thickened with microballoons at the leading edge, which makes it much easier to sand. I also use a small template to check the profile of the leading edge at different places of the wing. The template I used for the Monerai is the same as the one I will use for the Diana4 – the wing profiles are not identical, but close enough. A good trick to make sure that you sand the wings evenly is to mark the entire wing with a pencil. Once the pencil stripes are sanded away you have sanded enough and any uneven parts are most likely to have been sanded out.
Sanding reduced the weight of each wing by almost 40gr. Both of them now weigh exactly 482gr each (I weighed the wings during sanding to make sure that they weigh the same).
After sanding the wings I fitted them to the fuselage. The wings are attached to the fuselage using 6mm aluminium pins that are glued into small bits of plywood that I inserted into the base of each wing during the build. On the side of the fuselage they fit into short aluminium tubes that I glued into the fuselage earlier. To ensure that these pins are in the right place I first make the two holes in the fuselage for the wing joiner and make sure that the openings in the fuselage are just big enough to keep the wings in the right place. I check the position of the wings using my laser, as well as by measuring the distance to the table and to the nose of the fuselage. I then fix the first wing using tape, remove the other side, and use a long 5.5mm drill (thanks Aliexpress) to mark where the hole for the aluminium pin needs to come. I do the same for the other wing. I then drill open the holes for the four pins, making sure that there is enough play to enable the pins to set themselves in the exact right position. After waxing the fuselage around the area where the pins go in I then glue the pins into the wings using thickened epoxy resin (with cotton flakes), put both wings onto the fuselage and wait for the epoxy to cure.
