Discussions

I'm working on a research piece testing various unusual aircraft configurations, and I've come across an issue maintaining smooth airflow over some of the components involved in a variable-geometry wing... thing. Basically, there's one section that changes in size, and rigid materials like the usual foam or sheet plastic don't have enough give to cover it. I've tried with kite material, but it gets too loose and starts flapping, the drag jumps and the flutter it introduces makes controlling the thing a serious challenge.

It occurred to me that what I really need is something stretchy. If you look at a bat's wing, it remains more or less taught even when the wing is tucked because the skin can stretch. Our setup here is similar to what happens between a bat's "fingers", in that there's a triangular(ish) section that widens and narrows as the wing moves, so in theory a similar solution should work for us. Unfortunately, I can't find anything that seems to mimic these properties - kite materials are generally designed to not stretch, and stretchy fabrics tend to be rather porous and therefore don't work very well as wings because the air goes through them instead of over them. I thought of some kind of plastic or rubber, but the only things that come to mind are things like balloons and latex gloves, and I'm not sure they're tough enough - grass landings are quite likely, and I think a puncture would probably cause the wing to tear.

Does anyone know of a a material that has a bit of stretch without being fragile or highly porous? If I can't find one, I'll have to work out some sort of sliding or telescoping setup, which eats into my weight budget.