This glossary explains commonly used terms and abbreviations related to UAV, UAS, high-altitude platforms and advanced air mobility, with a focus on actuator requirements and system architectures.
The definitions are intended to support engineers, system integrators and decision-makers in understanding the technical context of unmanned aerial systems and safety-critical actuation technologies.
Advanced Air Mobility is a broader aviation concept encompassing urban, suburban and regional air mobility solutions based on advanced, highly automated aircraft technologies.
AAM includes eVTOL and eSTOL platforms integrated with advanced avionics, automation and airspace management systems. Typical use cases include passenger transport, emergency missions and time-critical logistics.
Actuators used in AAM platforms must support frequent duty cycles, high reliability, fail-safe behavior and minimal maintenance, meeting both safety and economic requirements.
HALE refers to unmanned aerial vehicles designed to operate at very high altitudes, typically above 15,000 meters, with some systems flying in the stratosphere at around 20,000 meters and beyond. Endurance ranges from several days to multiple weeks.
HALE UAVs operate where conventional aviation effectively ends, providing persistent wide-area coverage from extreme altitudes. They complement MALE platforms and satellite systems and are often deployed as part of High Altitude Platform Systems (HAPS).
Mission profiles include strategic ISR, communications relay, early warning and environmental monitoring. Actuators used in HALE platforms must withstand extreme pressure and temperature conditions while delivering precise, reliable control throughout long-duration missions.
HAPS refers to a class of airborne platforms designed to operate in the stratosphere, typically at altitudes between 18,000 and 25,000 meters, for extended periods ranging from weeks to months. Rather than being defined by a specific aircraft type, HAPS are characterized by their operational role: providing persistent regional coverage.
HAPS platforms bridge the gap between satellite systems and lower-altitude UAV platforms such as MALE and HALE. They offer satellite-like capabilities while remaining within the atmosphere, enabling lower latency, recoverability and flexible system upgrades compared to space-based solutions.
Typical mission profiles include telecommunications relay, earth observation, environmental monitoring, disaster response and wide-area surveillance. Most HAPS concepts rely on solar-electric propulsion, resulting in highly weight- and energy-optimized system architectures.
Actuators used in HAPS platforms must operate reliably under extreme environmental conditions, including very low atmospheric pressure and temperatures below −70 °C, while remaining lightweight, energy-efficient and capable of precise control over long operational lifetimes.
MALE describes a category of unmanned aerial vehicles designed for operations at medium altitudes over extended periods. These platforms typically operate between 3,000 and 9,000 meters and achieve endurance times of 24 to 48 hours, depending on mission profile and payload.
MALE UAVs bridge the operational gap between short-range tactical drones and HALE systems. They offer a balanced combination of payload capacity, range and operating cost, making them widely used across military, governmental and civil applications.
Typical missions include intelligence, surveillance and reconnaissance (ISR), border security, maritime patrol, environmental monitoring and disaster response. Actuators used in MALE platforms must provide reliable, precise control under reduced atmospheric pressure and low temperatures throughout extended mission lifecycles.
Urban Air Mobility describes the integration of airborne transport solutions into urban environments, primarily using highly automated eVTOL platforms.
UAM focuses on safety, low noise and environmental sustainability, supported by dedicated infrastructure such as vertiports, charging systems and digital traffic management.
From a technical standpoint, UAM platforms place high demands on actuation systems, which must enable precise control during vertical take-off, landing and transition phases under frequent operational cycles.
UAS refers to the complete system required to operate an unmanned aircraft. It includes the UAV itself, ground control stations, communication links, software, payloads and all supporting infrastructure.
The term UAS emphasizes a system-level perspective, recognizing that safe and effective unmanned flight depends on seamless interaction between airborne and ground-based components.
Within a UAS, actuation systems play a critical role in enabling reliable control of flight surfaces, propulsion and payloads. These actuators must deliver high precision, robustness and long operational lifetimes under demanding environmental conditions.
A UAV is an aircraft that operates without a human pilot onboard. UAVs may be remotely piloted or operate autonomously based on onboard computers and sensor systems.
UAVs exist in a wide range of sizes and configurations, from small multirotor drones to large fixed-wing aircraft capable of long-endurance missions. Applications include surveillance, mapping, inspection, logistics, environmental monitoring and research.
From a technical perspective, UAV performance relies heavily on flight control and actuation systems. Actuators enable precise control of flight surfaces, propulsion elements, landing gear and payload mechanisms and must be lightweight, energy-efficient and highly reliable.
eVTOL refers to electrically powered VTOL aircraft using distributed electric propulsion systems. These platforms are a key enabling technology for Urban Air Mobility (UAM) and Advanced Air Mobility (AAM) concepts.
eVTOL aircraft are optimized for short- to medium-range missions with high operational frequency. Typical applications include air taxi services, medical transport, logistics and unmanned aerial operations.
Actuators in eVTOL systems must provide fast, precise and reliable control during vertical flight, transition and landing while remaining lightweight, energy-efficient and suitable for frequent duty cycles.
VTOL describes aircraft capable of vertical take-off and landing without conventional runways. This enables operations from confined or unprepared areas and provides high operational flexibility.
VTOL platforms exist in both manned and unmanned configurations and are used in military, logistics, emergency response and industrial applications. Common VTOL architectures include tiltrotor, tiltwing, lift-and-cruise and multirotor designs.
VTOL systems impose demanding requirements on propulsion, control and actuation systems, particularly during transition phases between vertical and forward flight.
