Netters; Mark Langford knows what he's doing. The critical temp for extruded polystyrene foam (blue Dow or pink Owens-Corning) is about 165F, a temperature that can be exceeded when a "KR of color" sits out on the ramp in the sun at your typical fly-in. However, urethane foam (polyisocyanurate or other) does not have this same critical temperature at which it loses its dimensional stability, and I believe Mark has used urethane foam for the majority of his construction.
One of the main problems with polystyrene foam and the temperature limitation that indicates the use of predominately white paint is that the plane will develop a case of the "bulges", where bumps and blisters, and later sags and valleys, as well as ridges, develop as the plane's structure heats up into that temperature. These are the things that can lead to delamination of the fiberglass skins and also make the plane look plumb ugly. This is besides the thermal effects on the structural airframe epoxy and the fiberglass skin epoxy, both of which have their own problems but not like the polystyrene foam. What was it Virg always says, "build to the plans"? If you don't know what you're doing, paint it white and you'll be on the safe side... Oscar Zuniga San Antonio, TX mailto: taildr...@hotmail.com website at http://www.flysquirrel.net _________________________________________________________________ Express yourself with MSN Messenger 6.0 -- download now! http://www.msnmessenger-download.com/tracking/reach_general
