The pre-preg I hope to source hardly weighs anything, because the amount of resin mixed into the fibres is the bare minimum for structural strength. A single CF spar down the middle, with ribs in, say 4 positions made up of 3 ply pre-preg, with a single carbon skin over the lot will weigh mere grams. It's an expensive method, true, but one I am familiar with. Not to mention the fact that the University has an autoclave on site we plan to use!

Truth be told, I am not as confident working with foam: all my experience at e-Go was either working with moulds, or applying patches in wet layups for small areas. It's also worth mentioning that as each wing will be 1m long, and has fins and rudders mounted at each end, there's going to be a certain dynamic load on the wing in multiple directions (certainly a torsional element from the rudder input), one which I'm not sure the foam can take.

Wet layup over a pocketed foam core certainly is a process worthy of consideration; in fact, it was the initial plan for the wing. However, due to the loading, I figured that the spar, rib and single skin method would work out substantially lighter. If no CNC sponsor steps forward, that may well be the process we have to go for, out of necessity rather than choice.

Anyone here able to hot wire cut foam?