> > Hi Allen, > > Danny Livingstone from Sasolburg, South Africa, build his entire KR2 > using this foam wherever foam was required.
The conventional wisdom is polystyrene foam is unsuitable. Whilst polystyrene easily hot wires, shaping the stuff is difficult, from my experience it tends to pill in 1/8th inch balls, so getting fine detail work much more accurate than 1/8 is difficult. Polyurethane foam sands to dust, and consequently you can smooth it much more accurately - better accuracy = less filler = less time = lighter. As a simple experiment get two bits of styrene foam and rub them together, then repeat the exersize with 2 bits of urethane foam, you will find out just how easy it is to shape urethane foam. It really is as easy as Mark L reckons on his web site. probably the guys with the most experience of working with foam are the surf board jock - have a google, this is one I found http://www.surfersteve.com/polystyrene.htm Polystyrene is much cheaper - and more readily available, but given that the cost of the aircraft will be dominated by the cost of the engine, avionic etc, saving a few bob on foam is probably unwise, I would go for the the most workable materials available Pete
