Course: Unmanned Aerospace Systems Operations and Payloads
Introduction
The concept of experimental technology demonstrator aircraft was proven successful with the Grumman X-29 aircraft program. Research, development, and flight test data were used to foster newer and more advanced fighter aircraft (Pace, 1991). This approach to aircraft development is still effective with regards to today’s practices. A proof of the value of experimental demonstrator aircraft in today’s aircraft design practices is the intriguing Dassault nEUROn. It is an Unmanned Combat Aerial Vehicle (UCAV) designed and developed as an experimental aircraft for the purpose of researching, testing, and developing design principles, aircraft components and enabling technologies for future advanced UCAVs. It is built by Dassault Aviation and a network of European companies which include Saab Aerosystems, Ruag Aerospace and Hellenic Aerospace Industry. The nEUROn program objectives include a very low radar and infra-red signature, autonomous flight, air-to-ground weapons delivery and an automatic detection and recognition of ground targets (Mercurio et al., 2015).
UCAVs design present significant difficulties and constraints. It requires the integration of multiple sub-systems and components with competing and conflicting physical and functional requirements. Throughout conceptual, preliminary, and detailed design, manufacturing and testing, engineers and manufacturers encounter significant engineering challenges pertaining to advanced aerodynamics, stealth capabilities, navigation, control algorithms, component integration and human factors (Sepulveda & Smith, 2017). Supersonic aircraft must operate at low speeds for take-off and landings. They must also often cruise at subsonic speeds and reach supersonic rates for relatively short spurts. Although delta wings are ideal for supersonic flights, delta wings with sharp leading edges exhibit poor performance characteristics at subsonic speeds. Moreover, delta wings optimize aircraft maneouvrabrility and maximum speed capabilities, but they present significant aircraft stability issues (Anderson, 2007). When it comes to powerplant selection, engineers face the challenge of balancing sub-system weight with thrust capabilities and the UCAV’s thrust requirements. They must also manage to maximize fuel efficiency and specific thrust while minimizing the size of the fan inlet (Zhu, Liang, Zhang, 2017). UCAV manufacturers also encounter the issue of survivability which requires stealth features to prevent the UCAV detection by enemy radars. Stealth requirements affect system complexity and aerodynamic performance (Sepulveda & Smith, 2017). Furthermore, UCAVs engineers must also address interoperability issues between the UCAV sub-systems, the UCAV and human operators and the UCAV and other infrastructures or other aircraft. These issues render complex and challenging the achievement of program and system objectives such as autonomous flight, air-to-ground weapons delivery and automatic detection and recognition of relocatable ground targets (Valavanis & Vachtsevanos, 2015). Therefore, what are the design characteristics and enabling technologies of the Dassault nEUROn UCAV for airworthiness, reliability, and survivability?
The Dassault nEUROn is configured as a flying delta wing with rounded leading edges to improve aerodynamic performance at subsonic speeds. The system is equipped with flight control surfaces on the trailing edge to improve aircraft stability in flight. It is integrated with a low-bypass turbofan: a Rolls Royce Turbomeca Adour MK951 Hybrid. A low-bypass turbofan is used to optimize thrust-to-weight ratio and fuel efficiency (Louis et al., 2014). This single engine is installed at the center-top of the design with a trapezoid intake to reduce infra-red signature (Jha, 2017). To enhance stealth characteristics, built-in low observable coating is used for the low radar cross section and the infra-red signature. The nEUROn design configuration also includes no vertical tail. Interoperability and the successful achievement of mission objectives is ensured through the integration of a global system monitoring and control system, an automatic flight management system, an autonomous vehicle control system, a data link management software, a smart integrated weapons bay, target detection algorithms, antennas, infra-red sensors, electro-optical sensors, radio-frequency sensors, and a real-time data link to operators (Louis et al., 2014)
Discussion
Airframe
The Dassault nEUROn UCAV is configured as a flying notched delta wing with no vertical tail. The nEUROn is composed of an all composite skin built on an aluminum frame (Withington, 2011). Parts and components materials also include high-performance alloys and titanium alloys. It is characterized by a length of approximately 9.4 m, a wingspan of approximately 12.4 m, an empty weight of approximately 4900kg, and a maximum take-off weight of approximately 7000 kg. The system is reportedly capable of reaching a maximum speed of approximately 268 m/s. It exhibits rounded leading edges, and its trailing edges are equipped with split flaps (Louis et al., 2014).
Powerplant
The Dassault nEUROn is equipped with a low-bypass turbofan: a single Rolls Royce Turbomeca Adour MK951 Hybrid. It reportedly generates about 30 kN of thrust (Archer, 2004). The Adour variants are typically equipped with a low pressure compressor, an internal gearbox bearing, a high pressure compressor, a combustion chamber, a high pressure turbine, a low pressure turbine, a low pressure compressor front bearing, a high pressure location bearing, an external gearbox, an intershaft bearing, an engine controls cambox, a high pressure turbine bearing, an oil tank and a low pressure turbine bearing. A variant that generates 30kN of thrust was achieved through an upflowed fuel systems, an updated fan section, a revised nozzle guide vane area and an upflow high pressure compressor (Ferguson, 1990).
Operational Payload
The Dassault nEUROn payload sub-system essentially constitutes of an automatic flight control system, a data link management software, a smart integrated weapons bay, target detection algorithms, antennas, infra-red sensors, electro-optical sensors, radio-frequency sensors, and a real-time data link to operators (Louis et al., 2014).
The nEUROn achieves one of its primary objectives consisting of automatic detection and recognition of ground targets with its Smart Integrated Weapons Bay (SIWB) sub-system. It is composed of a ground segment, a SIWB control box and an air segment. It controls the aircraft’s attack capabilities. The SIWB control box is used to plan and monitor attack missions (Mercurio et al., 2015). It is technically part of the nEUROn ground control station. The air segment of the SIWB constitutes of multiple components which include a mission controller, an electro optical processor, an integrated optronic head, an environmental control system (ECS), weapons bay doors and mechanism. The mission controller functions include monitoring the SIWB sub-system health status, interfacing with the avionic system and controlling the weapons bay doors and weapons launch mechanism. (Mercurio et al., 2015). The electro-optical processor functions include searching, detecting, tracking, and recognizing potential targets. Its data processing algorithm is based on scanning for target and background IR signatures. The Integrated Optronic Head essentially constitute of a sensor payload. It functions include the acquisition of high resolution images, video tracking and processing. The ECS monitors temperature, pressure, humidity, and other environment conditions in the Integrated Optronic Head bay (Mercurio et al., 2015).
The nEUROn is equipped with both remote-piloting and autonomous flight capabilities. Its autonomous flight control sub-system essentially constitutes of an advanced autopilot capable of automated take-off and landings and automated aircraft trajectory control with defined flight plans (Louis et al., 2014). Such autopilot systems are generally equipped with a microprocessor that issues aircraft control commands and monitors aircraft altitude and position through the use of control loop designs. The nEUROn is also equipped with Electro-Optical (EO) and Infra-Red (IR) sensors. The EO and IR sensors are used to search, detect, track, and recognize potential targets. While IR sensors are typically used to detect heat signatures from ground targets, other aircraft, and other systems of interest, EO sensors provide data such as position, altitude, and speed of potential targets with respect to the UCAV (Atkins et al., 2017).
Command, Control, and Communication
The nEUROn is equipped with a data link management software. It controls communication and data transmission between the UCAV and its ground control station (GCS) through the use of both high rate and low rate data links. The nEUROn high rate links are compliant with STANAG 7085 which is the North Atlantic Treaty Organization (NATO) standards for Interoperable Data Links for Imaging Systems (“Dassault picks Thales for nEUROn Data Links”, 2005). This ensures interoperability between the nEUROn’s payload and its other sub-systems. It also ensures interoperability between the nEUROn UCAV and its GCS and between the nEUROn and other air traffic management infrastructures on the ground. The nEUROn datalink management software ensures the secure transmission of data which includes imagery data, video data, radar data and vehicle command and control data (“Dassault picks Thales for nEUROn Data Links”, 2005).
Ground Control Station
The nEUROn ground control station (GCS) is essentially constituted of two human operators, a deployable ISO 20 shelter on a high mobility wheeled vehicle, an all-weather EM environment, ground control computers, hardware and software, and voice communication devices (Louis et al., 2014). Its capabilities include an integrated voice communication with air traffic controllers. The nEUROn GCS sub-system and its components are compliant with STANAG 4671 which is the North Atlantic Treaty Organization (NATO) standards for UAV systems airworthiness requirements. The two ground operators are essentially systems monitors responsible for the UCAV’s command and control. Their function includes system health monitoring, flight plan validation, collection and showing of real time video and imaging data, radar data and other vehicle command and control data. GCS operators also validate, verify, and confirm target acquisition data and provide weapons delivery authorization (Louis et al., 2014).
Theory of Operation, Operational Capabilities and Performance Requirements
The nEUROn launch method is a conventional wheeled take-off which requires a runway. Ground operators handle communication with air traffic controllers and clear the aircraft through engine start, taxiing, and take-off phases (Louis et al., 2014). To complete its horizontal take-off, the UCAV’s turbofan produces the thrust required and accelerate the aircraft until take-off velocity is reached and the minimum lift required for take-off is generated. The nEUROn flight plan is predefined by its operators who monitor the aircraft throughout its flight. The aircraft is also capable of autonomous taxing, take-off, flight plan management and autonomous trajectory correction maneuvers (Louis et al., 2014). Once in flight, the nEUROn follows its flight plan and uses its IR and EO sensors to autonomously search, detect, track and recognize its targets. Acquired target data is sent to ground operators for confirmation. Upon validation, verification, and confirmation of a ground target by the operators, the nEUROn deploys its weapons on the ground target (Mercurio et al., 2015). Aircraft survivability during missions is ensured through its stealth characteristics which include a tailless design configuration and built-in low observable coating used for the low radar cross section and the infra-red signature. The UCAV recovery method constitute of a wheeled landing. Ground operators are responsible for clearing the aircraft for landing. The aircraft is also capable of automated landings (Louis et al., 2014). Power and thrust are decreased in preparation of the landing phases and the aircraft descends from the air to the runway. The nEUROn then decelerates during a ground roll until the vehicle reaches a stationary position. The ground roll typically requires the application of system brakes and the use of flight control surfaces like flaps to decrease power and spoilers to decrease lift (Anderson, 2016). The table below displays performance characteristics and physical specifications of the Dassault nEUROn versus the X-47 B.
Synthesis, Analysis and Evaluation
Strength, Limitations and Constraints
The Dassault nEUROn flying notched delta wing configuration is ideal for high speed vehicles. It optimizes the fixed wing aircraft maneuverability capabilities. The rounded leading edge improves aircraft performance at subsonic speeds (Anderson, 2007). The tailless design configuration enhances the aircraft stealth capabilities. The use of a turbofan as a propulsion system substantially improves the aircraft thrust-to-weight ratio and fuel efficiency. Turbofans are durable, reliable and generate significantly lower vibrations than other types of jet engines (Mattingly, 2006). With both remote-pilot and autonomous control capabilities, the nEUROn exhibits redundant vehicle control capabilities that improves system reliability and operational safety. The aircraft autonomous flight management capabilities and automatic take-off and landing capabilities renders the nEUROn rapidly deployable. Supported by the use of EO and IR sensors, its autonomous target search, detection, tracking, and recognition capabilities minimize the probability for human errors during critical air strike on ground targets missions (Guastello, 2014). It also renders the nEUROn one of the most innovative, reliable, and tactically advanced UCAV ever built. The nEUROn stealth capabilities ensure aircraft survivability and the successful accomplishment of mission critical objectives.
Despite its advantages, the nEUROn exhibits system weaknesses highlighted by its defined program objectives. In fact, the nEUROn is a demonstrator aircraft which is not configured for real combat applications (Mercurio et al., 2015). Deploying the nEUROn for such applications shall be considered a very high risk for the mission. The development of UCAVs like the Kratos XQ-58 A demonstrate that the nEUROn exbibits deficiencies in air-to-air combat and air-to-air weapons delivery capabilities. The aircraft flying delta wing configuration also present significant aircraft stability issues which is mitigated through the use of trailing edge flaps (Shearwood et al., 2020).The nEUROn airframe and wings design configuration possibilities are constraint by the program stealth requirements which often limits aircraft systems to a delta wing, a lambda wing, and a blended wing body configuration. Finally, the nEUROn was constrained to a program development budget of approximately 405 million Euros (Katz & Osborne, 2014).
Recommendation
Recommended future systems, enabling technologies and capabilities.
An evaluation of the nEUROn UCAV system characteristics and mission capabilities reveal an outstanding vehicle that exhibits advanced aerodynamics and performance characteristics and tactically advanced weapons systems. Maximizing the capabilities of the nEUROn will require a vehicle fully configured for real time combat applications. The nEUROn shall be equipped with the most advanced and innovative systems being currently developed for UCAV platforms. When it comes to the aircraft propulsion system, significant progress has been made with fuel cell engines and hybrid fuel electric engines. Equipping the nEUROn with such engine types shall improve aircraft endurance and propulsive efficiency and minimize its environmental emissions. The nEUROn also exhibits an advanced weapons system that can be enhanced with smart bombs, high powered lasers, and microwaves. Newest development in UCAVs design have demonstrated the value of air-to-air combat and air-to-air weapons delivery capabilities. Integrating the aircraft with such capabilities shall make the nEUROn the most advanced and versatile UCAV ever designed.
Possible Future Uses
Given that the nEUROn is a technology demonstrator, it must leverage newest development, technologies, and capabilities in UCAV design. It is reasonable to expect a fully configured UCAV for real combat applications derived from the nEUROn research and development efforts. The nEUROn will also possibly be used to develop a naval variant like the Northrup Grumman X-47 B. One of the most logical future use of the nEUROn is a design adaptation to a loyal wing-man application concept similar to the Kratos XQ-58 A, the Airpower Teaming System and the Sukhoi S-70 B.
Conclusion
The Dassault nEUROn is a remarkable Unmanned Combat Aerial Vehicle (UCAV) which is characterized by a flying notched delta wing with no vertical tail. It is equipped with a low-bypass turbofan: a single Rolls Royce Turbomeca Adour MK951 Hybrid. The Dassault nEUROn payload sub-systems essentially constitute of an automatic flight control system, a data link management software, a smart integrated weapons bay, target detection algorithms, antennas, infra-red sensors, electro-optical sensors, radio-frequency sensors, and a real-time data link to ground operators. The nEUROn is equipped with both remote-piloting and autonomous flight capabilities (Louis et al., 2014).
The Dassault nEUROn delta wing configuration is ideal for high speed vehicles. It supports optimum aircraft maneuverability capabilities. The rounded leading edge improved aircraft performance at subsonic speed (Anderson, 2007). The tailless design configuration enhances the aircraft stealth capabilities. Its autonomous target search, detection, tracking, and recognition capabilities minimize the probability for human errors during critical air strike on ground targets missions (Guastello, 2014). It also renders the nEUROn of the most innovative, reliable, and tactically advanced UCAV ever built. The aircraft is limited by its lack of robust real combat capabilities and stability issues which characterizes its flying delta wing airframe configuration. Nevertheless, it is important to note that trailing edge flaps are incorporated for the purpose of mitigating such stability issues (Shearwood et al., 2020). Maximizing the capabilities of the nEUROn will require a vehicle fully configured for real time combat applications. The nEUROn exhibits an advanced weapons system that can be enhanced with smart bombs, high powered lasers, and microwaves.
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