Quadcopters are primarily a form of VTOL (vertical take-off and landing vehicle) rotorcraft that has four rotors or propellers that enable the propulsion. The first attempt to create quadcopters was documented in 1907 by Jacques and Louis Berget. They created a prototype and tested quadcopters; however, their early designs were unstable and flight seemed impractical. Étienne Boehmite, a French engineer, was able to create a stable quadcopter in the year 1924 Figure 1 that was able to fly for around 360m (1,181ft), which created a world record.
The US army also created quadcopters and carried out flight testing, however the programme was later scrapped. Quadcopter early designs had just one single main rotor that was attached to the tail rotor so that overall counterbalance could be achieved. The prototype of using a single main rotor was of no use and added complexity to the process.
The single rotor used around 15% of energy while there was no thrust created to enable the lifting of the quadcopters. The other issue was related with the large rotor blades, which were heavy and around 5 meters long, making the quadcopters inefficient. Most quadcopters have the engine set in the fuselage while four rotors are driven through shafts or belts.
Quadcopters’ major challenge is maintaining stability by managing to uphold the same speed through all of the rotors (Krossblade, 2016).Figure 1: Quadcopter done by Étienne Oehmichen in 1924Dr. George E. Bothezat designed a Convertawings Model A quadcopter in the year 1956 and it was the first model to use propulsion to enable the forward thrust; this meant that operators were able to control the yaw, pitch and roll of the aircraft. The quadcopter went through significant changes over a period of time while companies like Blade, DJ, Parrot and others have added new technology like flight controls and the ability to do aerial photography. The quadcopter has further added features like a co-axial helicopter and agility against wind resistance, while it has also used three axis gyro technologies to enhance the level of stability. ESCs (Electronic Speed Controllers) are enabled so as to control flight with a remote-controlled transmitter. There are various kinds of aerodynamics used by the quadcopter so that it can be steered through its four rotors.
The quadcopter relies on its centre of gravity to manage its balance and it is based around a simple design concept. The quadcopters use has increased dramatically in recent years and they are widely used in the field of research and robotics, and research in harsh and dangerous places; used by the military and community agencies for various tasks (Quadcopters Arena, 2017).The 20th century has witnessed the rise of quadcopters and they are now widely used as a technology-driven innovation product for surveillance, GPS system enabled tracking, various research work at dangerous places like active volcanoes, and for tracking flood situations and other natural calamities. The technology of quadcopters gradually became cost effective and with their ease of use they became quite popular with the public for entertainment, photography and for the supervision of public works. The way forward centres around using quadcopters to replace police patrolling the streets; Amazon also has plans to use them for the delivery of goods, and the construction industry uses them for overall work monitoring and supervision.
Their small size, their ability to travel at fast speeds and to access places that are not easily supervised by humans are the qualities that make the quadcopter quite popular and in demand (Hoffmann, Huang, Waslander and Tomlin, 2007).