Understanding and developing drones are passionate about a range of things. The aerodynamic shape of propellers, strength, and weight of drone parts, motor, electric speed controller, sender or receiver, and software interface on mobile or computer for monitoring and data analysis are all variables within the design of a drone for a particular use.
2.1 Forces Of Flight #
When a drone moves within the air, various forces act thereon. The resultant force will decide its movement. There are major forces performing on a drone.
Each rotating propeller produces two reasonably forces. When a rotor rotates, it’s propeller produces upward thrust given by F=K_f * ω² (shown by forces F1, F2, F3 and F4 in Figure 2.2) where ω (omega) is rate of rotation of a rotor (radian/second). Many factors influence the constant K_f, including torque proportionality constant, back-EMF, density of surrounding air, area swept by propeller, and so on. The values for K_f and K_m (mentioned below) are generally found empirically. We mount the motor and propeller on a load cell and measure the force and moment for various motor speeds. Refer “System Identification of the Crazyflie 2.0 Nano Quadrocopter” by Julian Forster for details regarding measurement of K_f and K_m.
Total upward thrust generated by all 4 propellers is given by summing all individual thrusts generated, for i= 1 to 4 it’s given by
F_i = K_f * ω²
Forces on a flight in Fixed Wing UAV
The above picture shows fundamental forces experienced by flight. Within the fixed-wing UAV, the lift is generated due to the airfoil section of wings. To stay the UAV on the wing condition to carry its altitude position the burden of the UAV must be supported by the lift forces generated by the wings.
2.1.1 Weight #
Due to the mass of the drone, the body mass force always acts within the direction of gravity. Higher the burden of the drone, more power is required to lift and move the drone.
Weight of drone = mass of drone × acceleration thanks to gravity
2.1.2 Lift Force #
The vertical force performing on the drone is termed lift. This force is thanks to pressure differences across the drone (in the vertical direction). Hence, the speed, size, and shape of the propeller blade decide the number of lift force. Lift is important to lift the body against gravity. To make this force, all four propellers run at high speed to lift the drone.