Mark, I guess I should have stated my thesis first. I was actually trying to defend your choice of darker colors. Guess I didn't get my point across very well. The post I was responding to was the one about parking your red bottom airplane on a hot ramp was going to do a Sambo on it and melt it down into butter. I was assuming the ramp temperatures would be something on the order of the temperatures measured on the surface of the red Lancair and would be within the Tg range of your post cured composite structures. It doesn't matter if you put it out in the sun while still black or baked it in an oven. They both result in a valid post cure. You documented the post cure back somewhere in the depth of your web site.
But, I am worried about Dana exceeding the Tg of his posterior in that black RV of his :-) Steve Eberhart Steven Eberhart wrote: > Interesting thought. Not jumping in on either side of this discussion > but those that know me know that I usually run off to find the nearest > expert to get the facts when a discussion like this comes up. In this > case I headed for my library. I don't think much of Martin Hollman but > in this case he is just reporting facts from reputable sources. In his > book "Modern Aircraft Design Volume 2" he lists some temperatures that > were measured by embedded thermocouples in the Red Lancair 320 factory > demonstrator. > > A surface temperature of 153F was measured on the top surface of the > wing on a 95F ambient day at Oshkosh. A surface temperature of 180F was > measured on a 104F ambient day. On the same type of surface but painted > white a surface temperature of 126F was measured on a 95F ambient day. > > The glass transition temperature for Safe-T-Poxy With room temperature > cure is 151F but when post cured at a temperature of 200F the glass > transition temperature goes up to 196F. > > I wonder if sitting out on a hot asphalt ramp would result in a post > cure that would actually increase the glass transition temperature. Just > don't think I would want to launch into the wild blue immediately after > the first environmental post cure before the surfaces had a chance to > return to normal temperatures. :-) > > Just the facts mam. Now on Dana's black RV-7 I think the only thing he > should be concerned with it the glass transition temperature of his > posterior :-) > > Steve Eberhart > > > Ameet Savant wrote: > >> Okay, >> >> I am not totally convinced with this argument. >> >> If the heat radiating from a really hot asphalt >> parking spot happens to delaminate your airfoil skin >> over and over again. The birds flights also impose >> repeated stresses on the delaminated skins. then >> eventually the skin might depart from the structure. I >> don't think an aircraft can fly only on it's "wood >> spars". >> >> You give the anology of the steel structure with >> fabric on it. well I don;t think the plane can fly >> with the fabric torn in many places. I am talking >> about the wing only... The fueslage might be ok. >> However, I wouldn't want to reskin my fuselage every >> few years. >> >> The pain looks great!... but I have concerns that it >> is an unneccesary risk for an otherwise beautiful job! >> >> my 2ยข >> >> Ameet Savant >> >> >>> I'm surprised that nobody's pointed out that >>> the manual says to >>> paint the thing white yet. My argument is that the >>> structure of this plane >>> is wood, not composite. All the composite stuff >>> does while on the ground is >>> help the airfoils and decks retain their shape >>> (kinda like fabric on a steel >>> tube plane). The spar and landing gear take the 1g >>> loads while sitting on >>> the ground. When flying, the skin temperature will >>> be down to ambient about >>> 100 yards down the runway on takeoff, if not while >>> taxiing, so it's not a >>> factor. >> >> >> >>> Mark Langford, Huntsville, AL >> >> >> >> >> __________________________________ >> Do you Yahoo!? >> The New Yahoo! Shopping - with improved product search >> http://shopping.yahoo.com >> >> _______________________________________________ >> see KRnet list details at http://www.krnet.org/instructions.html >> > > > > _______________________________________________ > see KRnet list details at http://www.krnet.org/instructions.html > >
