Introduction¶
Drone 101¶
Sriraj Srihari
Introduction¶
This article will go over the basics of drones. However, it is wise to start with the bare bones basics of what a drone even is. A common name that professionals use for drones is unmanned aerial vehicle (UAV). Another name is a copter, with the prefix of copter meaning how many rotors it has. For example, a quadcopter has four rotors, while an octocopter has eight. Quadcopters are probably the most common style of copter since it offers good stability, while also being easy to work with. Drones tend to be lightweight, since they do not use tons of power like planes do. A small rechargeable battery can allow lightweight hobby drones to fly for at least 30 minutes, while certain drones have larger batteries that can allow them to fly for even longer.
Frame¶
The most important part of a drone is its frame. Without it, there will be nothing to hold up the different components that a drone needs to fly. They tend to be made from very lightweight materials such as carbon fiber, plastic, metals, or even 3D printed filaments. The frame can be made extremely lightweight because the plastics/composites tend to have a decent strength to weight ratio, meaning they can hold a lot of weight even though they are light. Since most drone components are lightweight, plastics can hold up most to all the components. Some camera drones or professional drones require the use of metal, as the components that go into those kinds of drones can be heavy, or just require a lot of strength to keep still. In this competition, the most common materials will most likely be plastics or 3D printed filaments. Small drones that only need to be in the air for a little amount of time tend to not require large batteries or complicated systems, so they tend to be made from plastics and are flimsy. Regardless, the strength of even plastic keeps it from shattering or breaking completely when dropped from a height. However, strength should always be checked before manufacturing a final frame, just so that there are no last-minute breaks that might impact the finished product of the drone. One big weak point in a frame can be along the rotor arm, as it extends away from the frame of the drone. When designing a frame, keep in mind that the rotor will sit at the end of the arm, weighing it down. The spot in the middle of arm tends to be the weakest in this scenario, as too much weight at the rotor end of the arm may cause the arm to snap.
Battery¶
All electrical components of the drone will need power, and that is where a battery comes in. Batteries will allow each component to get the power it needs so that the drone can stay in flight for as long as needed, while also being able to perform its tasks. The most common type of battery used is a Lithium Polymer battery, also called a LiPo battery. LiPo batteries are used in drones as they are lightweight compared to other types of batteries. They offer strong current while providing the right amount of voltage as well. While LiPo batteries have lower energy density (energy over a certain volume), they are much lighter than other batteries, are safer to work with, and have an overall energy capacity greater than most other batteries. They also recharge quickly, which decreases time between flights.
Motors¶
Drone motors vary in style, but the most common type is brushless. Motors will give the drone lift, allowing it to fly. Varying speeds of motors can make the drone turn, lift, drop, or do tricks. When choosing a motor type, either look for brushless or brushed. Brushless motors will last longer due to the way they spin, but both motors will provide lift and motion. When choosing a motor, important things to look for are thrust to weight ratios and kv, which stands for constant velocity. Thrust-to-weight ratios are important since the motors will need to be able to lift the drone. The constant velocity (kv) rating tells you what the rpm of the motor is when one volt is applied to it. While a high kv value might be good in certain situations, note that higher kv motors tend to be larger, and may not always be suited for your exact purpose. Sometimes, it is better to go with a lower kv if your application requires it.
Propellers¶
Propellers attach to the motor, and the spin of the propellers is what moves the drone around. The size of a propeller blade matters, as smaller blades tend to offer more aerobatic flights, while larger blades offer stability. There are “middle ground” blades as well that offer both stability and maneuverability, but if your application needs high maneuverability, then smaller blades might be helpful. Blades tend to be made of plastic or carbon fiber, as they are very light. Most importantly, blades are specific in the sense that one side needs to be facing up and one side down. This is because blades are not flat, they have curves that help air move around the blades and placing the blades the right way will give you the best results.
Electronic Speed Controller (ESC)¶
The ESC provides the drone the ability to fly. It will give the flight controller the ability to control the direction and speed of the drone. An important thing to keep in mind when choosing an ESC is the voltage and the maximum current the ESC can handle. The motors will need a specific current to work correctly, and you must make sure that the ESC can take the total current that all the motors need, as well as the flight controller current as well. The ESC connects the flight controller to the motor, and sometimes the ESC will need to output its voltage and current to a power distribution board so that the split is even, and each motor will get its correct power.
Flight Controller/Autopilot¶
The flight controller talks to the motors of the drone and any other electrical components that might need external controlling. The flight controller is what receives data from a radio controller and uses the ESC to “talk” to the motors. Flight controllers come with certain firmware and software that can be used to control the system, but radio controllers can be connected as well. Certain flight controllers also have modules in them that take down data such as velocity or position. The flight controller can also take inputs from other controllers and sensors to get data back. For example, you can connect a gyroscope to a controller so that the controller can relay the position and angle data back to the gyro, and the gyro can send that information back to a computer. The flight controller is the most powerful piece of the drone’s electronics, as it acts as the “motherboard” to the rest of the drone. It can handle telemetry and control, and can even be programmed in junction with a gyroscope to create a control system, where deviances in drone flight can be corrected by the controller automatically, without needing to manually fix it.