>\My brother owns a vari-ez and the right tank developed a leak that desolved >about 6" of the foam in the wing. He swears that using mogas only on 2 >occasions caused the failure. However it's anyone's guess as to what kind >of epoxy >was used as he didn't build it.
A Vari-Eze is supposed to be built with Urethane foam around the tanks. Urethane is impervious to gasoline. Assuming that you mean the outboard wing panels that are made from polystyrene, any gas (Mo or Av) will dissolve the foam. If you spill gasoline on the glass surface of the outer panel of a Vari-Eze wing, it can migrate through the glass into the foam and damage the structure. This is a caution in the Rutan plans. I did a test to satisfy myself about all the gasoline issues. I had a sample specimen of Last-A-Foam and fiberglass in a sealed jar of Mogas for 4 years. There was no sediment, no discoloration, no delamination, and no apparent loss of strength of the sample. The Resin was Easy-Poxy II. There are numerous reports related to Mogas. The majority of them appear to be anecdotal and I disregard them. The ones that seem to have a solid technical basis indicate that a good quality resin will be impervious to gasoline (Mo or Av) if it is properly mixed; i.e., several minutes of mixing while scraping the sides and bottom of the container, the initial temperature is correct (greater than 70 F, preferably more), and no dilution agents are included. If you take a batch of epoxy and mix it for 30 seconds, the ultimate strength will be on the order of 90 percent of a properly mixed batch. In a structural application, you will probably not notice the difference. The resin/hardener chemical reaction would not be complete. Portions of the mixture are soluble in gasoline or alcohol and will come out in solution and cause problems. It is my opinion that if you use a good quality epoxy and mix it properly, taking care to eliminate pinholes, there should be no problems with the tanks, using either Mo or Av gas. Don Reid - donreid "at" erols.com Bumpass, Va Visit my web sites at: AeroFoil, a 2-D Airfoil Design And Analysis Computer Program: http://www.eaa231.org/AeroFoil/index.htm KR2XL construction: http://users.erols.com/donreid/kr_page.htm Aviation Surplus: http://users.erols.com/donreid/Airparts.htm EAA Chapter 231: http://eaa231.org Ultralights: http://usua250.org VA EAA State Fly-in: http://vaeaa.org
