The Lightcraft is a fascinating and productive application of SDI technology. The craft itself is shaped like...well...sorta like two cones back to back with a curled lip in between. The lower cone, and the lip that curls down from its base (or top, in this configuration), is shaped so that the lip and the surface of the cone just opposite the lip form a continuous parabolic reflector. The focal point of the reflector is an imaginary torus that circles the lower cone between the lip and the cone surface, both of which are polished. The craft is placed (with this cone facing down ) over the C02 Gas laser. The laser is then pulsed repeatedly. Each time the laser fires, the laser light collecting at the parabolic focal toroid heats the air extremely rapidly. The air expands, and the higher air pressure underneath the lightcraft causes it to accelerate upwards. If the laser is pulsed quickly enough, the lightcraft will rise away from the laser and the surface...the process creates a series of flat bangs as the air around the lightcraft lower hull expands explosively.