Unmanned aerial vehicle
An unmanned aerial vehicle or unmanned aircraft system, commonly known as a drone, is an aircraft with no human pilot, crew, or passengers on board, but rather is controlled remotely or is autonomous. UAVs were originally developed through the twentieth century for military missions too "dull, dirty or dangerous" for humans, and by the twenty-first had become essential assets to most militaries. As control technologies improved and costs fell, their use expanded to many non-military applications. These include aerial photography, area coverage, precision agriculture, forest fire monitoring, river monitoring, environmental monitoring, weather observation, policing and surveillance, infrastructure inspections, smuggling, product deliveries, entertainment and drone racing.
Terminology
Many terms are used for aircraft which fly without any persons on board.An unmanned aerial vehicle is defined as a "powered, aerial vehicle that does not carry a human operator, uses aerodynamic forces to provide vehicle lift, can fly autonomously or be piloted remotely, can be expendable or recoverable, and can carry a lethal or nonlethal payload". UAV is a term that is commonly applied to military use cases. Missiles with warheads are generally not considered UAVs because the vehicle itself is a munition, but certain types of propeller-based missile are often called "kamikaze drones" by the public and media. Also, the relation of UAVs to remote controlled model aircraft is unclear in some jurisdictions. The US FAA now defines any unmanned flying craft as a UAV regardless of weight. Similar terms are remotely piloted aircraft and remotely piloted aerial vehicle.
UAVs or RPAVs can also be seen as a component of an unmanned aircraft system, which also includes a ground-based controller and a system of communications with the aircraft.
The term UAS was adopted by the United States Department of Defense and the United States Federal Aviation Administration in 2005 according to their Unmanned Aircraft System Roadmap 2005–2030. The International Civil Aviation Organization and the British Civil Aviation Authority adopted this term, also used in the European Union's Single European Sky Air Traffic Management Research roadmap for 2020. This term emphasizes the importance of elements other than the aircraft. It includes elements such as ground control stations, data links and other support equipment. Similar terms are unmanned aircraft vehicle system and remotely piloted aircraft system. Many similar terms are in use. Under new regulations which came into effect 1 June 2019, the term RPAS has been adopted by the Canadian government to mean "a set of configurable elements consisting of a remotely piloted aircraft, its control station, the command and control links and any other system elements required during flight operation".
In common usage, "drone" is often applied to both military and civilian UAVs, while technical and regulatory documents may prefer terms such as UAV, UAS, RPAS, or uncrewed aircraft. The term drone has been used from the early days of aviation, some being applied to remotely flown target aircraft used for practice firing of a battleship's guns, such as the 1920s Fairey Queen biplane floatplane and 1930s de Havilland Queen Bee biplane. Later examples included the Airspeed Queen Wasp and Miles Queen Martinet, before ultimate replacement by the GAF Jindivik. The term remains in common use. In addition to the software, autonomous drones also employ a host of advanced technologies that allow them to carry out their missions without human intervention, such as cloud computing, computer vision, artificial intelligence, machine learning, deep learning, and thermal sensors. For recreational uses, an aerial photography drone is an aircraft that has first-person video, autonomous capabilities, or both.
The term "Uncrewed" is sometimes used rather than "unmanned" when referring to UAVs.
Classification types
UAVs may be classified like any other aircraft, according to design configuration such as weight or engine type, maximum flight altitude, degree of operational autonomy, operational role, etc. According to the United States Department of Defense, UAVs are classified into five categories below:| Group: | Group 1 | Group 2 | Group 3 | Group 4 | Group 5 |
| Size | Small | Medium | Large | Larger | Largest |
| Max takeoff weight | < | > 20 & < 55 | > 55 & < 1320 | > | > |
| Operating altitude | < | < | < | < | > |
| Speed | < | < | < | Any speed | Any speed |
Other classifications of UAVs include:
Range and endurance
There are usually five categories when UAVs are classified by range and endurance:| Range category | Very close | Close | Short | Medium | Long |
| Range : | < 5 | > 5 & < 50 | > 50 & < 150 | > 150 & < 650 | > 650 |
| Endurance : | 0.5 – 0.75 | 1–6 | 8–12 | 12–36 or 48 | > 36 or 48 |
Size
There are usually four categories when UAVs are classified by size, with at least one of the dimensions meet the following respective limits:| Category | Micro/Very small | Mini/Small | Medium | Large |
| Length/wingspan: | < 50 cm | > 50 cm & < 2 m | 5 –10 m | > 10 m |
Weight
Based on their weight, drones can be classified into five categories:| Category | Nano | Micro | Miniature or Small | Medium | Large |
| Weight: | < 250 gm | ≥ 250 gm & < 02 kg | ≥ 02 kg & < 25 kg | ≥ 25 kg & < 150 kg | ≥ 150 kg |
NATO uses a similar classification shown below:
File:UASclassification.png|thumb|NATO classification of Unmanned Aerial Vehicles
Degree of autonomy
Drones can also be classified based on the degree of autonomy in their flight operations. ICAO classifies unmanned aircraft as either remotely piloted aircraft or fully autonomous. Some UAVs offer intermediate degrees of autonomy. For example, a vehicle may be remotely piloted in most contexts but have an autonomous return-to-base operation. Some aircraft types may optionally fly manned or as UAVs, which may include manned aircraft transformed into manned or optionally piloted UAVs. The flight of UAVs may operate under remote control by a human operator, as remotely piloted aircraft, or with various degrees of autonomy, such as autopilot assistance, up to fully autonomous aircraft that have no provision for human intervention.Altitude
Based on the altitude, the following UAV classifications have been used at industry events such as ParcAberporth Unmanned Systems forum:- Hand-held altitude, about 2 km range
- Close altitude, up to 10 km range
- NATO type altitude, up to 50 km range
- Tactical altitude, about 160 km range
- MALE up to and range over 200 km
- HALE over and indefinite range
- Hypersonic high-speed, supersonic or hypersonic or suborbital altitude, range over 200 km
- Orbital low Earth orbit
- CIS lunar Earth-Moon transfer
- Computer-assisted carrier guidance system for UAVs
Composite criteria
Lift type
FFLO
Forward flight lift only classified by ICAO with the aircraft type designator FFLO - UAV refers to plane-like dronesVFHC
Vertical flight/hover capability classified by ICAO with the aircraft type designator VFHC - UAV refers to drones using rotaing blades for lift as well as motionPower sources
UAVs can be classified based on their power or energy source, which significantly impacts their flight duration, range, and environmental impact. The main categories include:- Battery-powered : These UAVs use rechargeable batteries, offering quiet operation and lower maintenance but potentially limited flight times. The reduced noise levels make them suitable for urban environments and sensitive operations.
- Fuel-powered : Utilizing traditional fuels like gasoline or diesel, these UAVs often have longer flight times but may be noisier and require more maintenance. They are typically used for applications requiring extended endurance or heavy payload capacity.
- Hybrid: Combining electric and fuel power sources, hybrid UAVs aim to balance the benefits of both systems for improved performance and efficiency. This configuration could allow for versatility in mission profiles and adaptability to different operational requirements.
- Hydrogen fuel cell: hydrogen fuel cells offer the potential for longer flight times than batteries yet stealthier operation than combustion engines. The high energy density of hydrogen makes it a promising option for future UAV propulsion systems.
- Solar-powered: Equipped with solar panels, these UAVs can potentially achieve extended flight times by harnessing solar energy, especially at high altitudes. Solar-powered UAVs may be particularly suited for long-endurance missions and environmental monitoring applications.
- Nuclear-powered: While nuclear power has been explored for larger aircraft, its application in UAVs remains largely theoretical due to safety concerns and regulatory challenges. Research in this area is ongoing but faces significant hurdles before practical implementation.