The upper sides of both Ventus wings are now done. This is the “easy” bit of the wing building. Before starting with the epoxy I first prepared the foam shells and cores. Using a brush on the vacuum cleaner I cleared the “angel hair” remains of cutting the foam. The parts of the upper shell are taped to the building board (which has carefully measured markings for the right position of all parts) and glued together with UHU POR. The leading and rear edge of the shells, as well as the area underneath the main spar, are covered with packing tape (make sure you find a version that doesn’t stick to epoxy). I also applied a few bits of double-sided tape to ensure that the ebechi stays into place.
The ebechi is painted with a primer to avoid it from absorbing too much epoxy. After the primer has cured, the side where the carbon and foam are applied to is sanded and cleaned.
I then prepared 45gr of epoxy resin (make sure you measure and note this down for the other wing shells – 35-40gr would have been ok as well). Using a small soft roller I applied the epoxy to the parts of the ebechi to be covered with carbon. Then I put the carbon in place and again applied epoxy to the carbon using the roller. After letting it rest for a bit I then used kitchen paper and a hard roller to remove excess epoxy resin from the carbon. I then added a bit of foaming agent to the remaining epoxy and applied that epoxy to the remaining areas of the ebechi wood (and also parts of the carbon).
I then put the ebechi with carbon into the foam shell (sticking it to the shell using the bits of double sided tape), after which I added the wing cores (make sure you position them carefully) and the top of the shell. I added some foam bits to the corners of the wing (to avoid them being pressed down too hard in the vacuum) and insert the whole board with wing into the vacuum bag. Using the vacuum cleaner I created a vacuum, and then attached my new vacuum pump. I stayed with the pump for a while to make sure it stabilises the pressure at -0.15bar and then I left it to run for around 12hrs (making sure that the room temperature is around 21 degrees). I use a timer to turn off the pump after 12 hours (usually late in the evening), leaving the wing in the bag until the next day.
After removing the board and wing from the vacuum bag I used a sanding block to remove any bits of ebechi or carbon sticking out (the carbon pins can be really nasty).