What are Quadcopters?

About Quadcopters:

• It is an unmanned aerial vehicle (UAV) or drone with four rotors, each with a motor and propeller.
• A quadcopter can be manually controlled or can be autonomous.
• It's also called a quadrotor helicopter or quadrotor.
• It belongs to a more general class of aerial vehicles called multicopter or multirotor.
• Principle:
  • The main principle behind the flight of a quadcopter is Newton's Third Law of motion, which states that for every action there's an equal and opposite reaction.
  • A quadcopter's propellers push air downwards. This causes an opposite reaction called thrust that pushes the quadcopter upwards against gravity.
  • Air movement comes from Bernoulli's Principle, with larger propeller blades and faster rotation creating more thrust.
  • When the propellers rotate (for example clockwise), the quadcopter will tend to rotate anti-clockwise. Rotational force is called torque. Helicopters solve this by using a tail rotor.
  • Quadcopters solve this by driving two diagonal propellers clockwise and the other two anti-clockwise. Thus, torque from one pair cancel that of the other.
  • When each diagonal pair of propellers rotate in opposite directions, their thrusts will be in opposite directions. The quadcopter will not be able to lift up or fly.
  • This is solved by having the blades of each diagonal pair of propellers shaped as mirror images of the other pair. Effectively, all propellers will push air downwards regardless of the direction of rotation.
• Applications:
  • They provide stable flight performance, making them ideal for surveillance and aerial photography.
  • Quadcopters, after being airborne, have the ability to hover in place, whereas fixed-wing aerial drones have to be on the move constantly.
  • Other application areas include delivery, land surveys, crop assessment, weather broadcasting, and more.