An unmanned combat aerial vehicle (UCAV), also known as a combat drone, is an unmanned aerial vehicle (UAV) that is armed and used for intelligence, surveillance, target acquisition, and reconnaissance as well as attack missions. UCAVs are capable of carrying precision-guided munitions, air-to-air missiles, and other weapons payloads.

UCAVs provide a number of potential advantages over manned aircraft:

• They can undertake dangerous missions without putting a human pilot at risk
• They can maneuver extremely well because they don’t have to accommodate a human pilot
• They can stay aloft for very long durations, far longer than is possible with manned aircraft
• Their payloads can be specialized for attack, surveillance or reconnaissance missions

Some of the best known UCAV platforms include:

Key UCAV systems

UCAVs have seen significant use in conflicts in the 21st century. They have been used extensively by the United States in war theaters like Iraq, Afghanistan, Pakistan, Yemen and Somalia for reconnaissance and targeted strikes. Other nations like Israel, China, Iran, Turkey and India are also developing UCAV capabilities indigenously. Military use of armed UAVs remains controversial with disputes around their legal status, morality of using autonomous attack systems, and potential for unintended engagement of civilian targets.

UCAV Design Considerations

The design of UCAVs shares similarities with manned attack aircraft but has additional considerations unique to their unmanned nature and mission profiles:

Airframe

• Aerodynamic efficiency – Long loiter times require efficient cruise flight which influences wing and airframe design
• Structural strength – Airframe must handle maneuvering stresses and payload weights over full unmanned mission duration
• Low observability – Radar evading stealth shapes and non-metallic materials are used on some UCAVs
• Corrosion resistance – Ability to operate with minimal maintenance over months or years
• Icing resistance – UCAVs have to fly through cold weather and deal with inflight icing

Propulsion

• Fuel efficiency – To achieve long endurance, turbofan or turboprop engines preferred
• Reliability – Engine-out capability needed for long flights over inhospitable terrain
• Low IR signature – Cooling infrared emissions helps avoid detection
• Noise reduction – Stealth requires dampening engine noise

Payload

• Weapons – Missiles, bombs and other munitions compatible with purpose and size
• Sensors – Electro-optical, infrared, synthetic aperture radar for surveillance and targeting
• Communications – Robust satellite and line-of-sight datalinks with encryption
• Computing – Onboard computers for controlling vehicle, mission systems and payloads

Control Systems

• Autopilot – Allows fully autonomous stabilized flight without pilot input
• Navigation – GPS, inertial systems and terrain mapping for accurate positioning
• Collision avoidance – Detect and maneuver to avoid other aircraft or terrain
• Target recognition – Distinguish targets and restrict weapon release to valid ones
• Health monitoring – Identify and respond to system failures and battle damage

The exact combination of capabilities depends on the operating environment, range, endurance, mission profile and other requirements dictated by military needs and budgets.

History of UCAV Development

Unmanned aerial combat vehicles trace their history back to early target drones and remotely operated vehicles used for training and weapons testing purposes:

Early Target Drones

• 1935 – First radio controlled aerial targets developed by UK
• 1946 – US Navy TDN-1 assault drone carries 2,000 lbs of explosives
• 1964 – Ryan Firebee jet-powered target drone enters wide use

These subscale target drones validated the concept of unmanned remote controlled flight. But they lacked sophistication as they were not designed as combat aerial vehicles.

Early UAV Experiments

• 1964 – US Navy develops jet powered QH-50C helicopter UAV
• 1973 – Israel pioneers real-time surveillance small UAVs after the Yom Kippur war
• 1982 – Israel uses UAVs successfully for reconnaissance and electronic warfare in the Lebanon war

These early efforts established the viability of unmanned vehicles for battlefield support roles. But it took until the 1990s before UCAV prototypes started taking shape.

Emergence of UCAVs

• 1994 – General Atomics Predator UAV designed for reconnaissance
• 2001 – Predator equipped with Hellfire missiles for strikes in Afghanistan
• 2006 – Northrop Grumman flies jet powered, low observable demonstrator
• 2018 – Major militaries commit to UCAV acquisition and development

After the watershed introduction of the armed Predator, many other UCAV designs have emerged alongside steadily improving technology demonstrations. A number of operational platforms are now deployed and new variants continue to evolve driven by military interests in exploiting unmanned technologies.

UCAV Operations and Control

UCAVs require specialized systems for control, planning missions, autonomous operation and integrating them into broader military operations:

Ground Control Stations

Dedicated ground stations with control consoles for UCAV operators provide:

• Mission planning systems
• Uplink for control, navigation and systems commands
• Downlink of sensor and status data from UCAV
• Display and analysis of reconnaissance information

Some stations are transportable for deployment at forward locations near operational areas. High bandwidth satellite communication links are typically used for reaching widely deployed UCAVs.

Semi-Autonomous Operation

Once launched on a mission, UCAVs have varying levels of autonomous capabilities:

• Automatic take-off and landing over pre-programmed routes
• Transition between loitering and transit flight modes
• Execution of search patterns and orbit points autonomously
• Return to base on command or if systems/communications fail

Higher level decisions like target identification and weapon release authorization may require human operator analysis of sensor feeds.

Mission Control Integration

Within larger military networks, UCAV operations require:

• Airspace deconfliction with manned aircraft traffic
• Integration with ground forces mission command networks
• Sensor and targeting data fusion across multiple domains
• Battle damage assessment after strikes

Effective coordination between multiple UCAV sorties and other fighting units is essential for fully leveraging their ISR and strike capabilities.

Managing and exploiting the volume of manned and unmanned airborne assets available to forces will require increasing levels of automation. But ultimate control by human commanders is likely to remain to oversee weapon employment decisions.

Design of Specific UCAV Platforms

Several operational and demonstrator UCAV platforms showcase a variety of aerodynamic, structural and systems designs tailored to performance requirements:

MQ-9 Reaper

Design features:

• Turboprop propulsion for efficient long endurance
• Capable of carrying mix of AGM-114 Hellfire missiles and GBU laser guided bombs
• Range of 1100 nmi with 14 hour endurance
• Satellite data link allows transcontinental operation
• 49 foot wingspan with 800 lbs max payload weight

A medium altitude, medium endurance UCAV that can be deployed globally. Well suited for counterinsurgency operations.

BAE Taranis

Design features highlight future combat drone capabilities:

• Jet engine integrated with body for stealth
• Internal weapons carriage without protrusions
• Flying wing shape for low radar observability
• ‘Smart skin’ adaptable radar absorbing materials
• Testing semi-autonomous flight, decision making and weapons guidance

Intended to demonstrate advanced UCAV technologies like low observability combined with combat autonomy.

Skat

Russian UCAV prototype highlights different design priorities:

• Wide variety of munition types – missiles, rockets, bombs
• Focus on high maneuverability attack profiles
• Runway independent vertical takeoff capability
• Use of Russian GLONASS satnav instead of GPS

Emphasizes short range tactical strike missions without reliance on fixed bases.

These examples illustrate how factors like endurance, stealth and autonomy are emphasized differently based on operational contexts and technological capabilities. Tradeoffs between payload, range and performance continue to drive iterative UCAV development.

Trends and Future Outlook

UCAVs have proven extremely capable when deployed in permissive environments and against technologically limited opponents. But they have some inherent limitations:

Limitations

• Restricted situational awareness compared to human piloted aircraft
• Vulnerable to signal jamming that break control links
• Inability to fully match reasoning of human subjects for weapon authorization decisions

Emerging Capabilities

• Increasing autonomy of flight controls, mission planning systems
• Onboard sense-and-avoid systems for dealing with other traffic
• Hardening against GPS and datalink jamming
• Improved airframe designs for greater payloads, range and stealth

These technology trends will help mitigate limitations while lack of human presence also creates opportunities:

• Persistence and risk tolerance for extremely long duration flights
• Algorithmic data analysis instead of human sensory perception
• Coordination of large autonomous teams acting as a swarm collective

The future of unmanned combat aerial vehicles promises continued innovation in autonomous behaviors, networking and artificial intelligence. Militaries are also investigating potential uses beyond conventional weapons – high power lasers, electronic attack, cyber warfare, swarming kamikaze drones etc. Strategic, ethical and doctrinal debates will co-evolve with technological capabilities while unmanned platforms get ever more deeply integrated across the entire spectrum of military conflict.

Frequently Asked Questions on UCAVs

What weapons can UCAVs carry?

UCAVs are capable of carrying a wide variety of guided missiles and bombs weighing from a few kilograms to over a ton. They allow the same precision munition types used by manned fighter jets and bombers to be delivered more persistently via unmanned platforms.

Do UCAVs lead to less civilian deaths in strikes?

Proponents argue that UCAVs with the ability to loiter for long hours over targets can choose exactly when to strike in order to minimize collateral damage. However others counter that over-reliance on remote sensor feeds leads to misidentifying targets resulting in unwanted civilian deaths from strikes. The link between fewer civilian casualties and UCAVs is thus debated and situation dependent.

Could terrorists get access UCAV technologies?

There are concerns that state manufactured UCAV systems could proliferate among non-state groups via theft, capture or illicit transfers the way other conventional weapons have spread in the past. However advanced UCAVs have extensive supporting infrastructure requirements for mission planning, control and sensor analysis that makes it difficult for non-state actors to weaponize captured vehicles effectively.

Are combat drones legal?

The legal status of armed unmanned aircraft under international laws of war remains under active discussion by policy makers and academics. Key considerations include adherence to principles of military necessity, proportionality and distinction between combatants and civilians. Individual UCAV strikes have to assessed contextually based on laws governing broader warfare.

How long until fully autonomous lethal UCAVs become a reality?

Most existing UCAV models require a human ‘in-the-loop’ at least for final authorization of lethal actions, if not directly piloting it. But growing autonomy of behaviors like independent takeoff/landing, navigation, target identification etc alongside progress in AI is leading to calls for eventual supervisory control or more extensive autonomy. Lethal authority is thus likely to gradually shift from full human control to human/machine collaboration based on technology developments meeting operational and regulatory approval. But a definitive transition point is difficult to forecast presently.

Conclusion

Unmanned combat aerial vehicles have emerged as a transformative platform that offers novel reconnaissance-strike capabilities compared to manned aircraft or missiles alone. Though early UCAVs focused on surveillance missions, their ability to carry precision armaments revolutionized counterinsurgency and cross-border targeting operations. Rapidly improving technologies and military interest promises UCAVs will continue seeing heavy investments and become integral to how battles are fought using both conventional payloads and more exotic arsenals. But they also face growing debate around ethical, proliferation and policy concerns emerging from their autonomous lethal potential which have to be weighed against strategic advantages offered. Regardless, unmanned combat aerial vehicles seem set to provide expanded tools for political violence in the 21st century through persistent, risk-tolerant machines serving the complex goals of the nations fielding them.