Multirotors are drones with more than two propellers driving on the aircraft. The most commercial and standard drone there is, the multirotor has many capabilities such as tricopter, quadcopter, hexacopter, and octocopter. The only differences are the number of motors and propellers and ESC’s, as well as the number of arms on the frame, and the required battery capacity. Tricopters are more agile, with fewer(three) motors and less time in the air. Quadcopters are pretty standard, with four motors and a decent flight time. The main problem is that with three and four motors, if one of them fails, then your drone is going to crash. On the other hand, with a hexacopter and octocopter, you will be able to land the drone if one motor fails. Hexacopters are safer for photography when it comes to flying with an expensive camera, but one motor failing will take away the yaw(rotating the drone left or right). This will force you to land. Octocopters are the safest bet when it comes to flying with a really expensive camera, because if one motor fails, the drone can continue with full functions.
There are lots of electrical motors out there for many purposes, but there are only a few that are good for a drone. Three motors will be needed for a tricopter, four for a quadcopter, six for a hexcopter, and eight for an octocopter. All the motors on the drone should be of the exact same size and weight, with all the same specifications. A typical type of motor on a drone is an outrunner motor, and all the motors on the drone need to fit with the ESC’s and the battery.
Electronic Speed Controllers (ESC’s):
Electronic Speed Controllers are a very important part of a multirotor, because they are what changes the transmitter and Main Controller signals into actual speeds for the motor. These ESC’s have to be combined with the right battery and motor type, or they will burn out rather easily.
Main Controller Board (MC):
The Main Controller Board is most likely the most important part of a multirotor. Because there are more than two motors, it would be too difficult to control the multirotor manually, which is where the Main Controller comes in. The main controller is what automatically adjusts the motors at the same time to keep the aircraft level and to allow it to move with the operator’s input.
The main controller is like the brain of the multirotor, telling it what to do and how to do it. There are many companies that sell Main Controllers, and the more advanced, the more expensive. Some main controllers even have GPS capability.
The propellers are what the motors drive to allow the quadcopter to fly. There need to be two propellers turning counter-clockwise on opposite sides of the drone, and two propellers turning clockwise on opposite sides as well. This allows the multirotor to fly, because one rotation must counter the other. Propellers come in all different materials and shapes, and each one best for a specific type of motor.
The frame is what gives the multirotor its shape, its structure, and its stability. The frame is like the skeleton of a multirotor, supporting it while the motors make it travel in the air. The frame is also something that can be made out of many materials, but should be strong and durable and lightweight. Two good materials for a frame is carbon fiber and aluminum. These materials are both lightweight and durable. Aluminum has one fault though, and that is bending.
Transmitter & Receiver:
The transmitter and receiver are what transmit the information from the operator or pilot to the multirotor. The operator inputs what they want the multirotor to do on the transmitter, and the receiver receives that pieces of information and sends it to the main controller. The transmitter and receiver are usually a unique pair that can’t be used with other types. There are different types of channels on the receiver that correspond to controls on the transmitter. For example, there are channels for the motors, for the camera and gimbals, and for different flight modes.
Camera & Gimbals:
The camera and gimbals are optional equipment that are uses for photography purposes. The camera can be anything that fits in the gimbals with the gimbals still retaining enough power to move. The gimbals are what moves the camera around for a better shot of the filming, instead of having to rotate the multirotor. There are lots of them out there, some with cameras and gimbals together for a specific multirotor. The camera and gimbals also usually take up a channel on the receiver apiece.
The battery is what powers everything on the multirotor. Without the battery, nothing would work. The battery is usually built with a type of circuit connected to the ESC’s and the main controller, so that it would not burn them out if the battery was damaged. For multirotors, LiPo(lithium-ion polymer) batteries are usually used, due to the amount of power they give out and their capacity. The larger the battery, the more flight time, but it is heavier and also requires more time to charge.
On site multirotors, you can get all the information about the multirotors.