An unmanned aerial vehicle (UAV), or unmanned aircraft system (UAS), commonly known as an aerial drone or simply drone, is an aircraft with no human pilot, crew, or passengers on board, which instead is either autonomous or controlled remotely. 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.
Unmanned aerial vehicle (UAV) 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 in military use cases. A missile with a warhead is generally not considered a UAV 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 mass. Similar terms are remotely piloted aircraft (RPA) and remotely piloted aerial vehicle (RPAV).
UAVs and RPAVs can also be seen as components of unmanned aircraft systems (UASs), which also include ground-based controllers and systems of communications with the aircraft. UAS was adopted by the United States Department of Defense (DoD) and the United States Federal Aviation Administration (FAA) in 2005 according to their Unmanned Aircraft System Roadmap 2005–2030. The International Civil Aviation Organization (ICAO) and the British Civil Aviation Authority adopted this term, also used in the European Union's Single European Sky (SES) Air Traffic Management (ATM) Research (SESAR Joint Undertaking) 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 (UAVS) and remotely piloted aircraft system (RPAS). Many similar terms are in use. Under new regulations which came into effect 1 June 2019, 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, sometimes 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.Note; the term "drone" refers to the male bee that serves only to fertilize the queen bee, hence the use of the name in reference to the DH Queen Bee aerial target. The term remains in common use. The term uncrewed is sometimes used rather than unmanned when referring to UAVs.
Autonomous drones also employ various advanced technologies 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 has first-person video, autonomous capabilities, or both.
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 (25 kg) > 55 & < 1320 (600 kg) > > 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 (km): < 5 > 5 & < 50 > 50 & < 150 > 150 & < 650 > 650 Endurance (hr): 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 (length or wingspan) meet the following respective limits: Category Micro/Very small Mini/Small Medium Large Length/wingspan: < 50 cm > 50 cm & < 2m 5–10m > 10m
Weight Based on their weight, drones can be classified into five categories: + Drone categories"Nano, micro, small: The different drone types in India & if Jammu-like strike can be averted". . ThePrint, 29 June 2021. Category Nano Micro (MAV) Miniature or Small (SUAV) Medium Large Weight: < 250 g ≥ 250 g & < 2 kg ≥ 2 kg & < 25 kg ≥ 25 kg & < 150 kg ≥ 150 kg
NATO uses a similar classification shown below:
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 (OPVs). The flight of UAVs may operate under remote control by a human operator, as remotely piloted aircraft (RPA), 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 (medium altitude, long endurance) up to and range over 200 km HALE (high altitude, long endurance) over and indefinite range Hypersonic high-speed, supersonic (Mach 1–5) or hypersonic (Mach 5+) or suborbital altitude, range over 200 km Orbital low Earth orbit (Mach 25+) CIS lunar Earth-Moon transfer Computer-assisted carrier guidance system (CACGS) for UAVs
Composite criteria An example of classification based on the composite criteria is U.S. Military's unmanned aerial systems (UAS) classification of UAVs based on weight, maximum altitude and speed of the UAV component.
Lift type
FFLO Forward flight lift only classified by ICAO with the aircraft type designator FFLO - UAV refers to plane-like drones
VFHC Vertical flight/hover capability classified by ICAO with the aircraft type designator VFHC - UAV refers to drones using rotating blades for lift as well as motion
Power 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 (electric): 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 (internal combustion): 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 (no heat signature) 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.
History
1800's Early drones The earliest recorded use of an unmanned aerial vehicle for warfighting occurred in July 1849,The Future of Drone Use: Opportunities and Threats from Ethical and Legal Perspectives , Asser Press Springer, chapter by Alan McKenna, page 355 with a balloon carrier (the precursor to the aircraft carrier) in the first offensive use of air power in naval aviation. Naval Aviation in the First World War: Its Impact and Influence, R. D. Layman, page 56 Austrian forces besieging Venice attempted to launch some 200 incendiary balloons at the besieged city. The balloons were launched mainly from land; however, some were also launched from the Austrian ship . At least one bomb fell in the city; however, due to the wind changing after launch, most of the balloons missed their target, and some drifted back over Austrian lines and the launching ship Vulcano.
The Spanish engineer Leonardo Torres Quevedo introduced a radio-based control-system called the TelekinoTapan K. Sarkar, History of wireless, John Wiley and Sons, 2006, , p. 97. at the Paris Academy of Science in 1903, as a way of testing airships without risking human life.Biodiversity Heritage Library. Mécanique Appliquée. - Sur le télékine. Note de M. L. Torres, présentée par M. Appell 3 August 1903, pp. 317-319, Comptes rendus de l'Académie des Sciences.Randy Alfred, "Nov. 7, 1905: Remote Control Wows Public", Wired, 7 November 2011.
1900s Significant development of drones started in the 1900s, and originally focused on providing practice targets for training military personnel. The earliest attempt at a powered UAV was A. M. Low's "Aerial Target" in 1916.Taylor, John W. R.. Jane's Pocket Book of Remotely Piloted Vehicles. Low confirmed that Geoffrey de Havilland's monoplane was the one that flew under control on 21 March 1917 using his radio system.Professor A. M. Low FLIGHT, 3 October 1952 page 436 "The First Guided Missile" Following this successful demonstration in the spring of 1917 Low was transferred to develop aircraft controlled fast motor launches D.C.B.s with the Royal Navy in 1918 intended to attack shipping and port installations and he also assisted Wing Commander Brock in preparations for the Zeebrugge Raid. Other British unmanned developments followed, leading to the fleet of over 400 de Havilland 82 Queen Bee aerial targets that went into service in 1935.