The Quadcopters have four motors that use four fixed pitch propellers. Mechanically, this is very simple compared to a helicopter. Coupled with the compact electric motor powered directly by the battery, its simplicity makes small model quadcopters increasingly popular in RC hobbies. Four-rotor aircraft are popular because they are mechanically simpler, safer (since the rotor is smaller), and easier to control through software.

According to the size of the quadcopter, we roughly divided the quadcopter into a Large quadcopter and a Small Quadcopter. There are many parts that are the same, for example, the flight control part is basically the same; but there are differences, for example, the power system part (including the motor and motor drive) may be completely different.

Large quadcopter

Large quadcopters are also divided into different levels depending on their carrying capacity. In general, if the clarity of the photo or video capture is required, the drones needed will be larger because the cameras they can carry will vary depending on the size. For example, DJI’s S800 Large quadcopter can be used to mount professional SLR cameras, mainly for filming.

There are also some that are much smaller, suitable for mounting sports cameras such as Gopro.

Naturally, the larger the drone, the heavier the weight. This means that the motor must do extra work to lift the drone off the ground and keep it in the air. Larger drones carry higher capacity lipo batteries that support the size of the drone, Choose lipo batteries for quadcopter is depend on their size.

When fully charged, these batteries keep the drone in the air for up to twenty to forty-five minutes.

For aeromodel enthusiasts, DIY a big quadcopter is not an easy task. You can buy a complete solution from a brand manufacturer and then assemble and debug it yourself, such as DJI’s S800 series. But for many fans, the price will be more expensive. You can also buy the kits and assemble them yourself. Kits that generally need to be purchased include: flight control, ESC, brushless motor, remote control, lipo battery, bracket, etc. The cost of purchasing component DIY according to your needs will be much lower.

DIY Large quadcopter requires more professional knowledge, such as the connection of the electronic part, the adjustment of the center of gravity of the aircraft structure, the frequency and interference of the remote control, and the adjustment of parameters such as the flight control PID according to the structure of the aircraft or the wind at the flight site. In short, if there is a problem in one of the connection, it will cause the aircraft damage or the aircraft will fall from the air or the aircraft will not be controlled by the remote control.

The agility of a quadcopter depends, in addition to the electronic speed controller, on the inertia of the propeller. As you can imagine, in general, the bigger and heavier the item is, the more difficult it is to slow down or accelerate. As a result, this results in a slower agility and responsiveness of large quadcopters.

Another point to note is that the Large quadcopter is dangerous because it has a large block and the propeller rotates at a fast speed. Therefore, you must choose no one, wide space, and a good view to fly. Sometimes the rotor fixing screw is loose or hitting a foreign object, causing the rotor to break and the propeller flying out. It can be very dangerous if the propeller hits a person, especially a vulnerable part of the eye. So for novices, it is best to adjust the four-axis with goggles to protect the eyes.

Small Quadcopter

Small quadcopter motor with fixed pitch propeller.

The Small Quadcopter is relative to the Large Quadcopter above, and we refer to the palm-sized quadcopter. In general, the Small Quadcopter uses the board directly as a carrier, and of course uses a separate stand.

Small Quadcopters generally cannot carry too heavy loads due to their small size. However, the principle used to study the aircraft, as a channel for the entry model, has been more than enough. The components of the flight control, ESC, motor, remote control, battery, bracket, etc. mentioned in the Large Quadcopter are all present in the Small Quadcopter, but may vary depending on the characteristics of the Small Quadcopter.

Benefits of Small Quadcopter:

1. Several times to several tens of times cheaper than the Large quadcopter
2. The danger is very small, basically can fly everywhere
3. Easy to carry, if the volume is small enough, you can fly indoors safely.
4. Design the flight control circuit board yourself and transplant the open source flight control program and algorithm. The flight control of the Large Quadcopter is generally a product of a commercial company, and the possibility of DIY is low.
5. Since the distance of the Small Quadcopter is limited, the remote control can be omitted and the smartphone can be used directly.

Small Quadcopter’s Choice of lipo batteries is related to their frame size, like 1000mah 3S 35C for 250 mm fpv, while smaller batteries such as 650mah 3S 11.1V 80C, 650mah 4S 14.8V 80C for 90mm to 150mm size Quad.