Why quadcopter?
It is intuitively clear that a quadcopter is an aircraft with four propellers / propellers and a vertical arrangement of their axes. The type of multicopter is determined by the layout of the frame (arms) and the number of motors/propellers. The most common copters have which the number of rays is equal to the number of propellers:
Tricopter (3 propellers)
Quadcopter (4 propellers)
Hexacopter (6 propellers)
Octocopter (8 propellers)
In turn, frames can have 3, 4, 6, 8, 10 or even more beams. Variants of coaxial arrangement of engines on the beam are also possible, but they are used less frequently. Let’s give an example: if there are 3 engines and propellers, and they are located on three beams, then this is a tricopter, but if two engines with propellers for each beam are placed coaxially on the same frame, then this is already a hexacopter according to the “Y” or “Y6” scheme ” (or “coaxial tricopter”). The same applies to the quadrocopter and octocopter according to the “X4” or “X8” scheme.
Hexacopter according to the scheme “Y” or “Y6”
Differences
What else could be the differences between them, except for the number of engines? Let’s try to understand in more detail.
Tricopters (“quadcopters” and hexacopters according to the scheme: Y3, Y4 and Y6 and Y4) — have a specific design. With the Y3 scheme, the design has a servo-based tail beam/beam slewing mechanism assembly (see photo below), which does not add reliability and can add problems when designing the copter. A small number of engines obliges the designer to increase their power, i.e., it is more difficult to obtain a large lifting force for additional equipment in this case.
However, there are fans of such schemes. Someone uses this design because of the aircraft-helicopter look and flight mode, someone finds it similar to the American Osprey and beats it in the design of the case. However, this scheme is used by enthusiasts for entertainment, flight stunts, FPV flights and filming with action cameras like GoPro.
Quadcopters (more rarely X8 octocopters) are the most popular, simple and versatile branch of copters at the moment. They are distinguished by the relative cheapness of components, stability, compactness and a minimum of thinking about mechanics. Thrust-to-weight ratio is sufficient to use gimbal with system cameras and GoPro. At the same time, maneuverability and weight still allow you to feel the enthusiasm and confidence when piloting.
With the right approach to the construction of a quadcopter, there will be enough thrust for all the payload that you may need, and flight time in order to enjoy the use. Using quadcopters (for example, DJI, the Phantom family, which is still very popular), you can achieve really impressive results in aerial photography. It is also worth noting the high maintainability of quad-beam quadcopters in case of crashes/accidents. A lot of people start with just such UAVs, since they are the very “golden mean” and a field for experiments.
Hexacopters and octocopters are the most stable, expensive and heavy devices. As a rule, the purpose of their appearance is high-quality shooting on heavy professional photo and video cameras. Such drones use powerful motors, batteries and bulky suspensions. Those. this is already a full-fledged professional filming equipment, and not amateur experimental designs.
But the more complex the equipment, and the more critical nodes it contains, the higher the probability of an unmanned device failure. In the case of “hexa” and higher multicopters, there are cases when one of the motors fails, the copter safely (not without nerves, of course) carried out a soft landing.