Propellers are devices that transform rotary motion into linear thrust. Drone propellers provide lift for the aircraft by spinning and creating an airflow, which results in a pressure difference between the top and bottom surfaces of the propeller. This accelerates a mass of air in one direction, providing lift which counteracts the force of gravity.
Propellers for multirotor drones such as hexacopter, octocopter and quadcopter propellers, are arranged in pairs, spinning either clockwise or anti-clockwise to create a balance. Varying the speed of these propellers allows the drone to hover, ascend, descend, or affect its yaw, pitch and roll.
Parameters of a standard propeller:
Diameter of a propeller: The end to end distance of the propeller is called the diameter of the propeller.
Pitch: Propeller pitch is a linear dimension usually expressed in inches, feet, millimetres, or meters, and is equal to the advance of the propeller in one revolution.
Drone propeller blades are most commonly constructed from plastic or carbon fiber. Plastic propellers are cheaper and more flexible, allowing them to absorb impact better. The increased stiffness of carbon fiber propellers, although providing less durability, decreases vibration thus improving the flight performance of the drone and making it quieter. Carbon fiber is also lighter than plastic, allowing weight savings.
If you are flying in winter or in a very cold climate, you might want to use a ABS propeller, as PC can become brittle and break more often. If you are flying somewhere very hot, you may need to use a glass fiber reinforced propeller as both ABS and PC can become very soft and less efficient/durable. For most pilots in most locations, PC propellers will be suitable and the most durable.
There are two types of propeller configurations. They are structurally the same with the only difference that they are mirror images of each other. This is because propellers move in the opposite direction/spin for stability purposes. The propellers ensure that they push the air down to generate and upward thrust.
For reference purposes, we shall use the following:
Type ‘A’ – Clockwise rotating propellers.
Type ‘B’ – Counter-clockwise rotating propellers.
The propellers are positioned such that the ones with the same direction/spin are placed diagonally opposite to each other.