CHAPTER 2

The Ins and Outs of Drones

What is a drone? Some people think of drones only as aerial vehicles. But they are much more than that. Drones that fly in the air are sometimes called unmanned aerial vehicles (UAVs). But some drones travel at sea. People usually operate drones using remote control devices. Some drones can also fly by themselves on a preset flight path. Once the flight path is set, a Global Positioning System (GPS) guides the drone.

Drones with four rotors are often called quadcopters.

Generally, a person is not on board a drone. But drones can carry people as passengers. The vehicle is still considered a drone if the person on board has no power to control the vehicle.

Drones come in many shapes and sizes. Military drones at sea often look like submarines. Fixed-wing UAVs look like gliders. Rotor UAVs resemble helicopters. Many rotor drones have four rotors, but some have eight or more. Some small UAVs can carry items such as books and medical supplies. Large military UAVs can carry big cameras and weapons for combat. Some of these UAVs weigh more than 4,000 pounds (1,815 kilograms) when empty.

Recharging and Refueling

Drones have limited flight times. When their battery power or fuel runs out, they need to be recharged or refueled. Large military drones use fuel to fly. Many small drones land on a drone port on rooftops or the ground to recharge their batteries. Some researchers are looking for ways to increase flight times for drones. In 2014 a student at the Massachusetts Institute of Technology (MIT) came up with a possible way to recharge small drones using power lines. Drones would perch on a power line to recharge their batteries.

The U.S. Navy X-47B drone refuels in flight in 2015. It was the first time an unmanned aircraft refueled while flying.

In 2016 aircraft manufacturer Boeing was granted a patent for a midair recharging system. The drone would have a cord called a tether. The tether could drop down and attach to a drone power station on the ground. The drone could stay in the air to be recharged instead of landing.

Boeing also designs sea drones. In 2016 Boeing built Echo Voyager. This drone submarine can dive to 11,000 feet (3,353 meters) below the water’s surface. It can stay underwater for at least six months. It has a hybrid electric-fuel system that allows it to recharge underwater. Unlike most other sea drones, it doesn’t need to return to a surface ship to recharge. After testing Boeing hopes to make these drones available for companies to buy.