We stumbled on a really neat article recently about a new patent by Windspeed, an aerospace company. The patent is for a bubble-type viewing area on the top of an airliner, where a couple of seats would move up into the bubble giving the passengers an unobstructed 360 degree view. To see pictures and a video on CNN click here (clicking will not take away from this article). This bubble will almost certainly be plastic and plastics have a long history in aerospace applications dating back to the 1930’s and 40’s.
One of the first acrylic applications was World War II aircraft canopies. Acrylic had been developed around 1930 and was found to be easily processed and shaped. It was about 8x stronger than glass and had natural UV-resistance to weathering (unlike many other plastics) and so was suitable for aircraft where strength and being lightweight was key. As much of a revelation as acrylic was, it still had some deficiencies – namely its impact strength was less than desired, and certainly not bullet-resistant, and it also scratched easier than conventional glass. Fortunately, there was another plastic available which could correct some of these deficiencies: polycarbonate. Polycarbonate had extraordinary impact-resistance and yes, could be made bullet -resistant (modern “bullet proof” glass is polycarbonate). Polycarbonate; however, had deficiencies of its own: it was prone to scratching and worst of all, would yellow and crack with sun exposure affecting visibility and even structural integrity.
Canopy manufacturers appear to have solved this problem with an innovative solution. Canopies are now often laminates, in that they have an outer acrylic shell (which can handle UV-exposure) with a polyurethane film (for absorbing UV-light) and polycarbonate underneath. This provides the “best of both worlds” as the polycarbonate core can provide its strength without the threat of scratching or weathering which would otherwise disfigure the canopy. Given the application would require strength and optical clarity, it’s very likely the new dome manufactured for Windspeed’s bubble will be a similar laminate.
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