fuselage fiberglass skins

[racer956]

Does anyone recommend against building fiberglass skins for the fuselage. Does anybody offer skins for sale. What about aluminum skins on the fuse. Thanks for all the info so far.

 

[Raceair]

Designer John Monnett tried a fiberglass shell installation early in the Sonerai 2 development, and he abandoned the idea...Some of the reasons may be localized buckling,(oil canning) and extra weight. A couple of sonerais have been built with aluminum fuselage skins. I have to believe that if it was cheaper, lighter, and easier, more would be done that way. It's hard to beat a small hat section stringer, and lightly painted fabric over the top for weight and cost....Ed

 

[oahupilot]

here is the math

ceconite/fabric is 3.16 oz per sq yard, you only need one layer.

fiberglass comes in diffrent weights per square, but a 2 oz per sq yard would have to be two to three layers thick to have enough buckling strength. Now your talking about a covering that weighs 4 - 6 oz per sq yard, unfinnished. now add on 30% increase in weight for resin, and maybe another 20% in filler, sealer and paint. you can reduce the weight of resin by using vacum bagging, but now you need molds, more gear, and more time.

fiberglass and fabric are UV sensitive and need to be sealed, which is actually accomplished by the same product, I use ekofill form stewarts aircraft system with good results. Fiberglass will still also require a coat of micro fill/ slury and lots of sanding before you can paint it. Sand then fill then repeat like 8 times.

At this point you might be wondering the advantages of composites over fabric?
structural strength, smoother finish than fabric, no loss of energy due to fabric vibrations. On the soneria the skin is not a structural member it provides no added strength to the fuselage all flight loads are dealt with by the chromoly tube chassis. So skinning the plane in fiberglass results in a plane that is just heavier and not any stronger than fabric.