Historians may note that World War II was the last great “movie war.” In those days, you could do many things that are impossible today, yet make for great movie drama. You can’t sneak a fleet of ships across the oceans anymore. Nor could you dig tunnels right under your captor’s nose. Another defining factor is that it doesn’t seem we seek out superweapons anymore.
Sure, we develop better planes, tanks, submarines, and guns. But we aren’t working on anything — that we know of — as revolutionary as a rocket, an atomic bomb, or even radar was back in the 1940s. The Germans worked on Wunderwaffe, including guided missiles, jets, suborbital rocket bombers, and a solar-powered space mirror to burn terrestrial targets. Everyone was working on a nuclear bomb, of course. The British had Hobart’s Funnies as well as less successful entries like the Panjandrum — a ten-foot rocket-driven wheel of explosives.
Perhaps the holy grail of all the super weapons — both realized and dreamed of was the “death ray.” Of course, Tesla claimed to have one that didn’t use rays, but particles, but no one ever successfully built one and there was debate if it would work. Tesla didn’t like the term death ray, partly because it wasn’t a ray at all, but also because it required a huge power plant and, therefore, wasn’t mobile. He envisioned it as a peacekeeping defensive weapon, rendering attacks so futile that no one would dare attempt them.
Parabolic reflectors are pretty handy devices. Whether you’re building a microwave antenna or a long-distance directional microphone, suitable commercial dishes aren’t that hard to come by. But a big, shiny mirror for your solar death-ray needs is another matter, which is where this pressure-formed space blanket mirror might come in handy.
Pressure-forming was a great choice for [NighthawkInLight]’s mirror. We’ve covered pressure-formed plastic domes before, and this process is similar. A sheet of PVC with a recessed air fitting forms the platen. The metallized Mylar space blanket, stretched across a wooden frame to pull out the wrinkles and folds, is applied to a circle of epoxy on the platen. After curing, a few puffs with a bicycle tire pump forms the curve and stretches the film even smoother. [NighthawkInLight]’s first attempt at supporting the film with spray foam insulation was a bust, but the later attempt with fiberglass mesh worked great. A little edge support for the resulting shiny taco shell and the mirror was capable of the required degree of destructive potential.
We doubt this process can be optimized enough to produce astronomy-grade mirrors for visible light, but it still has a lot of potential applications. Maybe a fiberglass radio astronomy dish could be pressure-formed directly with a rig like this?