The SimCity 4000 Microwave Powerplant

The basic idea for the lightcraft is simple -- the acorn-shaped craft uses mirrors to receive and focus the incoming laser beam to heat air, which explodes to propel the craft. Here's a look at the basic components of this revolutionary propulsion system:
* Carbon-dioxide laser - Lightcraft Technologies uses a Pulsed Laser Vulnerability Test System (PLVTS), an offspring of the Star Wars defense program. The 10 kw pulsed laser being used for the experimental lightcraft is among the most powerful in the world.
* Parabolic mirror - The bottom of the spacecraft is a mirror that focuses the laser beam into the engine air or onboard propellant. A secondary, ground-based transmitter, telescope-like mirror is used to direct the laser beam onto the lightcraft.
* Absorption chamber - The inlet air is directed into this chamber where it is heated by the beam, expands and propels the lightcraft.
* Onboard hydrogen - A small amount of hydrogen propellant is needed for rocket thrust when the atmosphere is too thin to provide enough air.

Prior to liftoff, a jet of compressed air is used to spin the lightcraft to about 10,000 revolutions per minute (RPMs). The spin is needed to stabilize the craft gyroscopically.