Over the sky- From helicopters to drones

Unmanned Aerial Vehicle, also known as UAV, UAS, or a drone, has a formal name as “multirotor,” and it was invented under technological evolution.

In the early 20th century, humans began to experiment with rotorcrafts, but an aircraft was not able to fly with only one rotor. Also, as the wings of the aircraft rotate, the reaction from the wings cutting the air will cause the fuselage to rotate toward an opposite direction, resulting in difficult steering.

To counter the torque effect created by the main rotor, a smaller rotor that rotates vertically was added at the end of the tail, and the aircraft was able to fly steadily, making the helicopter we know today.

FBW Makes Easier Operation

In the past, the pilot’s control stick in an aircraft was connected to wing flaps through a mechanical linkage. By adjusting the flap, an aircraft can climb and descend. The faster the aircraft flies, the greater the drag force flaps generated, and the pilot had to adjust the flap angle with a matching force. After the end of World War II, the mechanical linkage was improved by using the hydraulic drive system, so the aerodynamic forces during flight could be slightly reduced.

In the 1970s, the F-16 fighter jet adopted FWB (Fly by Wire), a system that links the engine and flaps. The pilot could control the aircraft by putting in simple commands for directions on an electronic interface, which decreased the possibility of rapid climb and descent during flight.

With advances in MEMS (microelectromechanical systems) in a semiconductor device, an accelerometer can sense direction changes and send the data through tens and thousands of electronic signals per second to the microcontroller unit (MCU). Then the accelerometer transmits measured rotation speed signals to different parts of wing flaps to stabilize the flight.

Advantages of Drones

The mechanical construction of a drone is much simpler than a plane and is with easier maintenance, but there are still challenges. For instance, most UAVs have a battery life of only half an hour. If a larger battery is equipped, the drone requires more energy to fly due to increased weight, and that drains the battery even faster.

To solve this problem, companies in China have proposed the use of fuel cells, claiming a battery life over 4.5 hours, but fuel cell technology has still not been widely commercialized. Google and Amazon even try to combine rotorcrafts and fixed-wing aircraft, such as general airplanes and gliders. Everything is still under test, but all things are possible.

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