91色情片

Dropping supplies to troops is often a matter of luck: there is no way of
ensuring they will land in the right place. But now researchers at the US Army鈥檚
Soldier Systems centre in Natick, Massachusetts have developed a robotic
parafoil that will steer itself to a target area, landing within just 100 metres
regardless of wind conditions. Parafoils are wing-shaped parachutes and can use
lift to travel considerable lateral distances. Some travel three kilometres for
every one km of altitude鈥攐r 32 km from a typical drop altitude. An onboard
GPS system keeps track of the parafoil鈥檚 position and uses its control cords to
adjust its descent trajectory.