Why are quadcopters the newest craze? Is it better than a helicopter? Are more propellers better? Does propeller size matter?
Here’s a comprehensive guide to multicopters, starting from one rotor going up to eight.
This is the OG copter. There is a single large rotor to provide thrust and a smaller tail rotor to control yaw. It’s a simple design that doesn’t require stabilization electronically.
This is because there’s only one rotor that provides thrust. However the helicopter does come with some issues.
A complex mechanism has to be used to rotate the main rotor, in order to control pitch so you can fly forwards or backwards.
Also, a large rotor is more prone to breaking and more dangerous. The propellers will have more momentum and higher velocity at the tips.
The upside is that a single large rotor creates a significant gyroscopic effect that keeps the helicopter stable. If you’re into RC recreation, the helicopter is still a great choice. It puts piloting a chopper as its priority and cuts away everything else.
Where the helicopter is lacking is how smooth the ride is. It isn’t ideal to equip a camera on. It also doesn’t take full advantage of recent technological advances.
The runt of multicopter designs, the tricopter configuration is not ideal and pretty much obsolete.
If you want to be a drone hipster the tricopter is for you.
The three rotor arrangement still ends up having a torque imbalance. One of the rotor shafts needs to be able to swivel (like a helicopter), in order to compensate for it.
The tri-copter is a half-measure option, which generally isn’t good. It made more sense when brushless motors and propellers were scarce and expensive.
The tricopter configuration doesn’t scale well, so it is mainly for light hobby usage.
The golden child of multicopter designs. Quadcopters are simple, elegant, and efficient. Having four rotors is symmetrical and the simplest way to control yaw, pitch, and roll. All 4 rotors are fixed-pitch, with no need to swivel them.
How a quadcopter flies is that each rotor is free to spin at different speeds. This creates four instances of thrust that can rotate the entire drone to go where it wants to go. Two rotors are spinning clockwise, and two counterclockwise. This results in a balance of total torque so the body stays stationary.
The success of the quadcopter is the result of a few key technological availability advances. Quadcopters require an electronic stabilization system to control rotor speeds. The system also translates your controls into individual rotor speeds. Previously you had to be a once-in-a-generation physics genius to control a quadcopter, which probably limited its market.
The quadcopter standard is the X frame. It is the simplest with least amount of material used, translating to a lighter weight and lower costs. It also creates a node ideal to place the electronics, battery, and camera. Another popular frame is the H-frame. Other alternatives include square or circular frames.
Nowadays with processors, smartphones, GPS tracking systems all widely available, quadcopters have exploded in popularity. They are easy to fly, with a range of computer-aided stabilization systems.
With recent advances in smaller cameras, aerial photography becoming very popular too. With quadcopter popularity increasing, manufacturing costs come down. The quadcopter has become THE ideal drone to get for most people.
Hexacopter and Octocopters
The powerhouses of multicopter designs. I’ve put hexacopter and octocopters into the same section because the concept of MORE ROTORS stay the same.
Whereas quadcopters maximize efficiency and simplicity with 4 rotors, hexacopters and octocopters offer more stability, smoothness, and safety. The addition of more rotors mean that overall, more power is used to lift the heavier frame. The whole thing becomes more stable and resistant to wind. It also means that each individual rotor can be smaller and spin faster.
This translates to a smoother flight, versus a quadcopter with similar overall dimensions but larger propellers.More rotors also mean more security. If a motor fails, the rest can pick up the slack.
A motor failure in a quadcopter will most likely result in a crash. If your payload is expensive photography equipment, you want to trust a hexacopter or an octocopter to haul it hundreds of feet into the air.However, the hexacopter and octocopter configuration also makes it less efficient. The frame is heavier and the motors draw more power. The demand is also not as high, so parts are more expensive and harder to find.
If you’re a professional photographer or cinematographer looking for a drone to capture aerial shots, an investment into a powerful, stable drone is worth it. The hexacopter and octocopter is ideal for high end aerial photography. As the commercial drone industry develops as well, these powerhouses may become more prominent. Definitely something to look out for.