Sid I had a similar occurrence years ago with my KR wing tanks made of Dow Derakane vinyl ester resin and Sunoco 94 octane gas. At the time I didn't think Ethanol was the problem but rather some kind of octane boosting solvent. Luckily I noticed it before running the fuel into the header tank or engine. Draining the tanks and letting it re-cure also worked for me. I now use Shell V Power 92 and test every load for ethanol with a simple water absorption test Works fine Regards Chris Gardiner kR2S 230 hours VW2180
Sent from my iPad On 2012-07-12, at 10:52 AM, "Sid Wood" <smw...@md.metrocast.net> wrote: > I remember Mark Langford saying that public confessions were good for the > soul or something like that. That also makes it more difficult to get > elected to political office. I am looking for neither of those concerns. > I once recommended building fiber glass fuel tanks using Vinyl Ester Resin. > All sources that I could find did say that Vinyl Ester was compatible with > the Ethanol found in most automobile fuels today. Conversely, Epoxy was not > compatible with Ethanol. I built the wing tanks in my Diehl wing skins > using Vinyl Ester Resin per the Diehl instructions. When I put in 92-octane > auto fuel containing 10 percent Ethanol, I got the same reaction as if the > tanks were made with Epoxy. Surfaces slowly started to dissolve, fuel > turned yellowish brown and a sticky brown goo starting clogging the sumps. > I researched my sources on the internet and all still confirmed my previous > conclusion. Looking a little further on solvency chemistry, I found > internet sites that address ways to enhance solvent action. Pure Ethanol, > gasoline and water are excellent solvents by themselves, but none of these > alone will effect cured Vinyl Ester. Adding 6 percent water to Ethanol will > produce a solvent that will slowly dissolve Vinyl Ester. So, how much water > would that actually be in auto fuel containing 10 percent Ethanol? The math > is easy: 10 percent of 6 percent is 0.6 percent. That's less than 1 ounce > per gallon. Where does the water come from? From the moisture in the air, > the Ethanol will readily adsorb the water in half full tanks, especially if > there is a vent like most aircraft tanks (like mine). > I now have drained the tanks and left the caps off. After 2 weeks the goo > on the inside surfaces has "re-cured" hard just like the original. The > quick-drains had become clogged and have been replaced. One concern is the > integrity of the tank walls; there is an imprint of the foam layer > sandwiched between the inner and outer wing surface, top and bottom, that > outlines the wing tanks. This imprint pattern appeared when the drying out > process was started. Any ideas what is going on with that? > Long term plan now is to use 100LL. > > Sid Wood > Tri-gear KR-2 N6242 > Mechanicsville, MD, USA > smw...@md.metrocast.net > > > > > _______________________________________ > Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. > To UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html
