One way to make airplanes fly exceptionally far and fast may be to get rid of their fuel and engines. That may sound outlandish, but powerful lasers may one day make it possible, says Takashi Yabe of the Tokyo Institute of Technology. To demonstrate the principle, he and his colleagues have been playing with paper airplanes.
Although light exerts a slight pressure on objects (SN: 9/29/01, p. 203: After a failure, a new craft to sail), that’s not the trick used in Yabe’s experiments. Rather, he and his colleagues glued to the tail end of their tiny craft a small square of aluminum on which they deposited a water droplet.
When pulses from a desktop laser vaporized some of the metal, the plane got a forward kick. Without the water, which served as a wall against which the metal plume could push, the plane wouldn’t go, Yabe says.
So far, he and his colleagues have shown that this approach can propel a plane off a lab table, but not keep it flying. They describe their experiments in the June 10 Applied Physics Letters.
In Yabe’s ultimate vision for aviation, lasers perched on mountaintops or balloons would flash their beams through the sky to propel high-altitude passenger planes. Water gleaned from the air to coat plates of metal or carbon would suffice for running those aircraft. In the nearer term, Yabe says he hopes that tiny, unmanned, laser-powered planes will be used to monitor volcanoes and the atmosphere’s chemistry.
