DIY-MedTech Dronen fliegen - Team Dagobert
A crash course into multicopters (or drones)
(Work in progress)
Since recently, flying a drone has become easily accessed to more people. Outside the military purposes, drones can be used as art installations (Verity), aerial imaging/surveying (Wingtra) or lightweight transport systems (such as Amazon Prime Air). Recently, drones has started to find its purpose in medical field, mainly to deliver blood packages between hospitals in rural areas (such as (Zipline in Africa or  Swiss Post drone).
Drones often come in two forms: fixed-wing aircraft and aircraft with rotor (helicopter or multicopter).
Comparison of Rotor and Fixed Wing
Multi-rotor drones are made of a central body and multiple rotors that power propellers to take flight and maneuver the aircraft. These usually have four rotors (quadcopter), but can have from two to six or eight rotors (resp. bicopter, hexacopter, octacopter). Once in the air, a multi-rotor drone uses fixed-pitch propeller blades to control the vehicle motion by varying the relative speed of each rotor to change the thrust and torque produced, allowing a unique range of movement.
Fixed wing drones are designed like more traditional types of aircraft — which look similar to an airplane. They are made of a central body that has two wings and a single propeller. Once in the air, the two wings generate lift that compensates for its weight — allowing the aircraft to remain in flight.
For this Medizintechnik DIY#Skill Share Sessions, multicopters are placed in focus.
Drones have at least two rotors (bicopter), but the majority has four rotors (aka quadcopters). Except for bicopter, which behaves quite similarly to fixed-wing aircraft (or the famed V-22 Osprey), the multicopters require that not all rotors should rotate in the same direction
The propeller pitch is a measurement of how far that a propeller will move through the air for every single rotation of the motor/propeller. This is only a theoretical approximation since real world factors such as prop material, air density, and efficiency can influence this distance. However, the pitch is a good measurement that will help you better understand your propeller performance.
The higher the pitch value, the faster your aircraft will move. In other words, with both motors/propellers spinning at the same RPM, the higher pitch propeller will travel further in the same amount of time. Changing the propeller pitch will also change the dynamic response of your drone.
The size of the propeller is the distance from tip to tip. Longer propellers can generate more thrust at the same speed, but requires more torque from the motor to turn the prop. A larger propeller size does not mean that you will be able to fly faster.
The surface area of the propeller also determines how much thrust it can generate. The higher surface area allows more air to be moved, thereby generating more thrust. This also comes at the cost of more power draw from the motor.
The length of your quadcopter frame determines the maximum size of propeller that you can use. For a square drone frame as below, the maximum propeller size is X/2. For a rectangle frame, the maximum size is Y/2