Futuristic electric drones

"People have been experimenting with drones for more than 150 years. During the U.S. Civil War, they tested hot-air balloons loaded with explosives on timing devices. These early drones were dangerously unreliable and uncontrollable. Spies in hot-air balloons proved the importance of aerial surveillance but also the risk. Technology soon caught up and made flying and spying using unmanned aircraft possible. Today, drones do more than ever before. Electric drones help save lives, deliver packages, perform shows, explore the Earth, and transport passengers. All different types of drones are making people's lives easier and better in many ways"--Provided by publisher.