I've used polystyrene, divinycell and the "green" foam for building boats.
Polystyrene we found hard to work with and that fuel dissolved it (show me a boat that doesn't get fuel in it :-) We then changed to vacuum moulding using divinycell and carbon fibre. 2oz woven fibreglass at 45 degrees to 4oz carbon fibre outside and 3/4oz carbon fibre inside on 1/4in divinycell is very tough and rigid (the outside 2oz fibreglass for sanding and finishing so the carbon fibre is not damaged during finishing). Now when I got my KR2 I had to modify the cowling so out came the divinycell (20 years old now). What a disaster. As I was not using a mould I had trouble getting the divinycell to the shape I wanted and sanding it was impossible. So down to the local branch of Fibreglass International to see what to use now. Green foam was the answer, I got a sheet and re-shaped my cowling, very easy to sand and shape but very soft and easy to dent. Once finished I had a layer of 6oz on both sides and it is way softer and more flexible than that made with divinycell. The discarded divinycell left on the ground can be walked on and have tools dropped on and be generally abused without denting or separating, but the green foam cut-out that was left over virtually fell apart when I gave it a little twist. All that said my cowling is way strong enough to guide the air around my engine and firewall, which is all it has to do, it is NOT structural. Most of the fibreglassing on a KR is non-structural, only to cover nicely shaped foam. We are after a well bonded, lite and rigid surface. Having bought a 99% completed KR2 I have missed the joy of building it. And after reading of this groups adventures of building, I am envious. I will build eventually but that will have to be after the kids finish college, 8 years or more, by then I wonder where the KR2 design will have evolved to? I can hardly wait. :-) I really want to investigate some of the new products (ie. carbon rods) and methods for building. The ramblings of a frustrated builder (I already have a 43ft X 60ft (13m X 18m) workshop. Barry Kruyssen Cairns, Australia RAA 19-3873 [email protected] http://users.tpg.com.au/barryk/KR2.htm ----- Original Message ----- From: Larry A Capps To: 'KRnet' Sent: Friday, July 23, 2004 10:46 PM Subject: KR> Foam vs. Foam I actually prefer Divinycell over Last-A-Foam for most applications. PVC Foam = Divinycell (rigid PVC) Clark Foam = Last-A-Foam (unicellular polyurethane) Larry A Capps Naperville, IL "You're just jealous because the voices don't talk to you." -----Original Message----- This may be a naïve question as I have not seen (touched) the stuff you call Lastofoam (Divinicel?). Maybe this is a mechanically stronger polyU, but the stuff locally available is very fragile - I can poke my finger all the way into it without much effort and the surface readily crumbles almost to a dust when rubbed - not an ideal surface to glue anything to. My wife uses it for flower arrangements. Styrofoam has its own draw backs in that Vinyl Ester resins (and most solvents /avgas) will attack it. _______________________________________ to UNsubscribe from KRnet, send a message to [email protected] please see other KRnet info at http://www.krnet.org/info.html
