A racing quadcopter is substantially different from common photography drones. Built for extreme speed, agility and durability, it’s controlled directly by the pilot without the use of GPS navigation or other computer assistance. With incredible acceleration and agility, it can reach a speed of over 140 kmh and fly for several kilometers given the right conditions and setup.
The frame of a racing quadcopter can be considered as its bones: the rigid structure that holds all the electronic components together. It’s generally made of the strongest carbon fibre to withstand frequent and hard crashes. In DCL, the minimum size is a diagonal of 325mm (motor to motor).
The thrust that accelerates and manoeuvres the copter is generated by plastic propellers, spun at variable speeds by powerful brushless electric motors. The ESC (electronic speed controllers) are responsible for delivering the correct amount of current to the motors, according to the required rotation speed. The most commonly used propellers for racing are 5 or 6 inches in diameter, with 3 blades. A single motor can output up to 1.5 kg of thrust for a total of 6 kg, applied to a Copter of 700g creating a thrust-to-weight ratio up to 8/1.
DCL racing quadcopters use 4-cell, high performance Li-Po (Lithium Polymer) batteries. They operate at a nominal voltage of 14.8 V and they can discharge up to 120-150 Amperes of current. Batteries can have different sizes and capacity, but they typically last up to 2-3 minutes of high speed racing.
The FPV (First Person View) system allows the pilot and the spectators to see – in real time – through the quadcopter’s robotic eye, allowing for an incredibly immersive, high speed, experience. The system consists of a small analog camera (usually around 600 tv lines), a video transmitter (VTX) and a FPV antenna. The VTX encodes the video captured by the camera and sends it to the receiver on the pilot’s goggles using a 5.8 GHz radio link with very low latency (approx 15ms).
A second antenna receives the commands of the pilot’s remote control through a secondary radio link. The receiver interprets them and communicates them to the flight controller. The flight controller is the “brain” of the quadcopter. Its main sensor is a gyroscope that measures its rotation speed. The FC compares the detected rotation speed with the one requested by the pilot and calculates, with precision, thousands of times per second, the necessary rotation speed of each single motor, so that the copter can execute what the pilot is requesting.
The FPV video system is optimized for extremely low latency, it’s video quality and resolution are generally very poor. For this reason most pilots use an HD action camera to capture stunning HD footage. The most commonly used are the GoPro Session, because of their form factor and quality of footage.
Apart from the main systems described, racing quadcopters often install other minor components: one of the most important is an array of colored LEDs, which makes the quadcopters easy to identify for other pilots and for spectators.