The concept of a flying machine originates in ancient Greece and China, whereas the first modern unmanned aircraft was demonstrated less than 15 years after the first flight by the Wright brothers. For several years these unmanned systems were used as target drones and it wasn’t until the 1950s that the first reconnaissance drones were developed, leading to today’s UAS. Today, a large number of countries are developing an equally large number of different systems for reconnaissance, surveillance, hunter-killer, weather monitoring, earth monitoring and other roles. Besides fixed-wing aircraft, there are also UAS based on helicopter designs, as well as back-packable, shrouded rotor, twin-rotor, lighter-than-air, tiltwing, canard rotor wing and other systems.