ISNE Bélos

ISNE Bélos
Belos in prototype camouflage
Role	air superiority fighter
National origin	Willink
Manufacturer	Institoúto Stratigikón Naftikón Erevnó
First flight	7 June 2021
Introduction	Q2 2025
Status	In development
Primary user	Willink
Produced	2025-
Number built	12

The ISNE Bélos is a sixth-generation air dominance fighter in development by Willinkian defense contractor Institoúto Stratigikón Naftikón Erevnó. The Bélos is designed to replace aging fourth-generation aircraft (the Questarian Dauntless and Shrike) and augment the multirole Bantam in Willinkian air service, as well as replace the F/A-77 Kovas/Havenfighter as the primary air dominance fighter in Willinkian use; the latter is to be adapted to a multirole/strike role. Initially conceptualized in 2014 as ISNE worked on missile block and cockpit support system updates for the Havenfighter, the Bélos undertook its first flight in 2021, and is scheduled to reach initial operation in early 2025. In air defense, the Bélos is intended to out-class its regional competitors and legacy platforms such as the Project 352 Nukefighter, Supermarine Sea Kestrel (Libertyfighter), and F-23 Helios (Setofighter).

Development

ISNE, under its anglicized trade name Strategic Naval Research Institute was a development partner with ARES Group on the F/A-77 Kovas, also known as the Havenfighter, being tasked with cockpit support systems and weapon system integration generally , one of two Willinkian manufacturers involved with the project alongside Gloucester Aviation. Further, in Willinkian examples of the aircraft, ISNE took on a greater role in systems integration, translation of software into native Willinkian, as well as designing a large percentage of the dedicated missile platforms carried by the plane in Willinkian service. Thereafter, it maintained an important localized role in maintenance and service upgrades, having close access to the production process, as well as test-bed aircraft to prototype and integrate new systems. In 2014, amid system upgrades intended to integrate the new Cheiron Block II SRAAM, ISNE started conceptualizing a successor craft to the Kovas, based on feedback from Willinkian pilots operating the platform, as well as their own experience with the plane's electrical and cockpit management systems.

Generally, the Kovas is a highly regarded platform by pilots, capable of (arguably) best in class maneuverability, stability at both low and high speeds, a complex, effective, powerful sensor suit, and possessing high survivability. However, several persistent issues were identified: the modular dual-layer RAM system required frequent inspections and replacements, especially in harsh environments like naval operations; at speeds above Mach 1.5–1.8, the Kovas RAM and composite materials over its lifespan tended to degrade due to aerodynamic heating, reducing stealth performance; the Kovas struggled with heat dissipation due to its powerful radar and engine, leading to IR detection risks and operational inefficiency; and the Kovas skin panels were designed for specific operational wavelengths, limiting adaptability to emerging threats with different radar bands or advanced detection methods. Combat experience with the aircraft demonstrated that the diamond wing and large canards of the Kovas would exacerbate drag and airflow disruption at slow speeds, reducing stability in dogfights or low-speed engagements or at extreme angles of attack. Finally, over time, as systems were upgraded (e.g., avionics, sensors, weapons), the airframe's weight and radar cross-section (RCS) would increase, negatively impacting its stealth profile and agility; the "future proofing" of the Kovas was under increasing strain with improvements made in machine learning and computing power, stressing the power supply systems in an already complex, electrically demanding aircraft.

Design

Aerodynamics

The Bélos sought to improve lift-to-drag ratios while maintain low observability, opting for a cranked-kite wing layout. The aircraft retains a similar rear layout to the Kovas, opting for a v-tail with "humped" engine integration into the fuselage. The Bélos mounts diamond-shaped canards as frontal control surfaces. This cranked-kite-v-tail-canard configuration was selected for its high AoA performance, excellent post-stall maneuvering, excellent yaw and pitch controls, and adaptability to both supersonic and subsonic regimes. At high speeds, the cranked-kite wing reduces wave drag, while at low speeds, canard-assisted vortex lift improves control and stability for landing or dogfighting. The combination of cranked-kite wings and canards ensures excellent longitudinal stability, even in scenarios where the aircraft's center of gravity shifts (e.g., as fuel is expended or weapons are deployed). The V-tail reduces cross-sectional drag while maintaining effective control authority for pitch and yaw, particularly important during high-speed flight. This configuration strikes a balance between stealth, maneuverability, and efficiency. Compared to other configurations, it offers superior multi-role performance by blending stealth optimization with aerodynamic versatility, enabling operations in high-threat environments against advanced radar and missile systems. The inclusion of canards and V-tail enhances agility and control, making it a more robust platform for high AoA and post-stall maneuvers. While it may not achieve the extreme stealth of a tailless design or the simplicity of a conventional wing-tail configuration, it is a well-rounded choice for scenarios demanding both survivability and dominance in contested airspaces.

The Bélos is set up in a configuration reminiscient of the Saab Viggen; its wings mounted nearly flush to the lower fuselage, minimizing the frontal radar cross-section (RCS) by reducing exposed edges and surfaces; above-wing engine intakes, mounted on the lower half of the fuselage and blended into the body line via a leading-edge extension; and canards mounted on the intakes above the wing. The loss of airflow beneath the aircraft, particularly during low-speed, high-angle-of-attack (AoA) conditions by the wing placement is mitigated by intake and canard placement generating vortex lift at high AoA. This layout blends stealth, high-AoA stability, better lift-to-drag ratios, and superior airflow control to the airframe.

Aerodynamically, the positioning of the engines and V-tail imposes specific challenges and opportunities. The "humped" engine integration creates a broader fuselage cross-section, which slightly increases drag, while also improving lift by contributing to the lifting body effect of the fuselage itself. Furthermore, the outward placement of the V-tail stabilizers enhances yaw and pitch stability by increasing the moment arm relative to the center of gravity. This configuration synergizes well with the diamond-shaped canards and cranked-kite wing, as the canards improve maneuverability and stability at high angles of attack, while the cranked-kite wing offers strong lift-to-drag ratios and low-speed stability. The V-tail's upward and outward angling also contributes to minimizing interference with the airflow over the wings and canards, ensuring smoother aerodynamics overall.

In terms of systems integration, the positioning of the V-tail and engines impacts the internal structure and layout of subsystems. The outward V-tail placement allows for more streamlined heat and airflow management around the engines, improving thermal dissipation and reducing the risk of thermal hotspots that could compromise stealth or operational efficiency. However, this arrangement requires precise engineering of control linkages and structural reinforcements to handle the aerodynamic loads transferred through the extended stabilizers during high-speed or high-G maneuvers.

Materials

Material engineering was a prime interest in the project, given the experience with the RAM systems of the Kovas. The Bélos employs cutting-edge materials to ensure superior performance in the high-stress environments characteristic of modern aerial combat, prioritizing thermal management, structural integrity, and stealth. Ceramic matrix composites (CMCs) are integrated into high-heat regions, such as engine nozzles and leading edges, due to their exceptional heat resistance, low density, and durability at temperatures exceeding 1300°C. These materials outperform traditional aluminum-titanium alloys, which are prone to thermal fatigue, offering lightweight strength ideal for sustained supersonic operations.

The airframe and structural components rely on thermoplastic-polyamide composites (principally PEEK), reinforced with carbon fibers, to create lightweight yet tough skin panels. These composites, fabricated through additive manufacturing, enable the formation of monolithic, seamless panels that eliminate radar-reflective seams, fasteners, and joints while enhancing damage resistance and operational flexibility. Nanostructured titanium-aluminum alloys are selectively used in high-stress areas such as wing spars and fuselage frames, offering unparalleled strength-to-weight ratios and compatibility with surrounding materials, reducing fatigue under extreme aerodynamic loads.

To address the Bélos’ thermal signature and operational heat loads, an active thermal control system combines loop heat pipes and metallic foam heat exchangers. These systems ensure even heat distribution across the airframe, reducing infrared detectability while improving system reliability during prolonged supersonic or supercruise flight. High-temperature radar-absorbing coatings mitigate traditional stealth degradation caused by heat buildup, ensuring consistent low observability even under extreme conditions. Advanced coatings also offer multi-spectral absorption, targeting both radar and infrared frequencies, while resisting erosion and environmental wear.

The Bélos opts to incorporate structural radar-absorbent material (RAM) woven directly into the thermoplastic-polyamide composite skin of the aircraft, rather than being sprayed, painted, or affixed. By embedding carbon-nanotube-based RAM into the skin itself, the aircraft achieves an inherent radar-absorptive capability that eliminates the need for traditional external RAM coatings. This structural RAM exhibits broad-spectrum absorption, effectively countering radar systems operating across X-, S-, C-, and Ku-bands, as well as lower-frequency systems increasingly used in early warning applications. The carbon nanotubes, renowned for their exceptional conductivity and electromagnetic properties, are finely tuned to dissipate radar energy through magnetic and dielectric losses, converting it into heat. To manage this thermal load, the RAM incorporates heat-dissipating properties, leveraging the Bélos' thermal management system to disperse the heat uniformly, preventing hotspots that could compromise performance or stealth.

Additionally, anisotropic materials are strategically woven into the structural RAM at critical points, such as the leading edges of wings, canards, and intake lips, as well as the V-tail surfaces. These materials guide radar energy along controlled paths, redirecting it away from the emitter and preventing backscatter. This design significantly reduces the radar cross-section (RCS), particularly at oblique angles where scattering is most likely. Unlike traditional RAM coatings, which may degrade under environmental stressors or high speeds, the structural RAM is inherently bonded to the aircraft's skin, making it exceptionally durable and resistant to delamination, erosion, or wear caused by extreme temperatures, supersonic flight, or adverse weather conditions.

The benefits of this approach are manifold. First, the weight savings achieved by eliminating separate RAM coatings improve overall performance, including range, agility, and fuel efficiency. Second, the durability of structural RAM reduces maintenance demands, minimizing downtime and life-cycle costs compared to aircraft requiring frequent reapplication of external coatings. Third, the seamless integration of RAM into the Bélos’ skin ensures uniform stealth across the airframe, with no weak points susceptible to radar detection. The broad-spectrum absorption also allows the Bélos to remain stealthy in the face of modern multi-frequency radar systems, including advanced active electronically scanned array (AESA) radars and low-frequency over-the-horizon systems.