A quadcopter is a multirotor aircraft that uses four motors for vertical take off, landing and flight. Vertical take off and landing has the advantage of eliminating sophisticated landing gear and does not require a runway or catapult to get the aircraft into the air. For example, a helicopter takes off and lands in a vertical fashion requiring only a landing pad or suitable level surface. Although there are many types of multirotors such as tricopters (three motor), hexacopters (six motor), etc. they all fall into the category of UAVs (unmanned aerial vehicles) or drones. To understand the basics of multirotors we are going to look specifically at the quadcopter because of its simplicity and popularity, the other varieties are more or less mutations of the same basic principles. Before we look at how quadcopters fly, let's take a minute to get to know the parts of a quadcopter or four motor multirotor.
What is a Quadcopter?
Quadcopters are really quite simple. A basic quadcopter consists of a frame, four motors with propellers, a flight controller, four ESCs (electronic speed controllers), a power module (or power distribution board), a battery and a radio controller (receiver and transmitter). More advanced quadcopters usually have a GPS/compass for navigation and telemetry radios to connect with a ground station, as well as some type of switch for arming/disarming the aircraft, a safety buzzer and an optional battery monitor. They may even have a sonar range finder for sense and avoidance of obstacles. If a quadcopter is to be used for survelliance of some sort or aerial photography/videography it may be equipped with a fpv (first person video) system or onboard video equipment such as a GoPro camera and gimbal.
Now that we understand what the basic parts of a quadcopter are lets have a look at what these parts do.
- The Frame: The frame carries all the components of the quadcopter and at minimum consists of a mounting plate attached to four booms for mounting the motors. Quadcopter frames usually consist of two or more plates.
- The Motors & Propellers: The motors and propellers provide lift and direction to the quadcopter.
- The Flight Controller: In simplest terms, the flight controller is the brains of a multirotor. It is the main "on board computer" of the quadcopter or multirotor.
- ESCs (electronic speed controllers): ESCs or electronic speed controllers, control the speed of each motor. Individual ESCs are connected to each motor, a common power distribution board and the flight controller. The best ESCs are flashed with SimonK firmware. In the case of quadcopters, individual ESCs may be combined into a single four-in-one component. These are called four-in-one ESCs and are super easy to install.
- Power Module or Power Distribution Board: A power module or power distribution board provides power from the battery or batteries to each ESC as well as other components such as a flight controller, video equipment etc.
- Battery: LiPo batteries provide the power to a quadcopter. These batteries range from 2S to 6S (the "S" is the number of cells) and a variety of capacities rated in milliAmp hours (mAh).
- Radio Controller (R/C): The radio controller gives the ground pilot the ability to fly the quadcopter or multirotor. Radio controllers have two parts to them, a receiver which mounts on the quadcopter and a transmitter which the pilot has in his hands. Quadcopters can be controlled with a radio controller, a ground station or in some cases both.
This list covers the basic parts, now let's look at some of the more advanced components of a quadcopter.
- GPS/Compass: A GPS/compass provides navigation and positioning data to the onboard flight controller and/or ground station.
- Telemetry Radios: A pair of telemetry radios connect the quadcopter or multirotor to the ground station. One radio is mounted on the quadcopter and connected to the flight controller while the other is connected to either a laptop, tablet or smart phone ground station.
- Ground Station: A basic ground station contains some sort of navigation type software. Some more advanced ground stations have the ability to set flight paths with waypoint navigation, autonomous return to home or receive flight information from the quadcopter such as altitude, yaw, speed, battery health, GPS health, etc.
- Arming Switch: An arming switch is used to both arm and disarm the quadcopter.
- Safety Buzzer: A safety buzzer emits tones or music to signal that a quadcopter is armed and ready for flight. As well, various tones can be used to communicate to the pilot that the flight controller is expecting a certain function such as an ESC calibration or experiencing a low battery condition.
- FPV (First Person Video): FPV stands for first person video which gives the ground pilot a first person view from the aircraft. FPV systems consist of an on board camera (usually mounted on the front of the aircraft), a transmitter/receiver and a monitor screen or FPV goggles. Some FPV systems even have the ability to record FPV video. An FPV system should not be confused with video setups specifically designed for taking aerial video footage.
- Aerial Videography: In order to take quality aerial video footage, quadcopters and multirotors can be equipped with a camera such as a GoPro and gimbal. The camera is mounted to the gimbal and the gimbal can be mounted to the front or underside of the quadcopter. Gimbals can be stationary or have several servo motors to provide various degress of rotation to the camera.
- Landing Gear: When a video setup is mounted to the underside of a quadcopter it is often necessary to add proper landing gear to allow ground clearnace for the camera and gimbal.