The Athlon-Avia ST-35 Silent Thunder is a Ukrainian loitering munition UAV designed for precision strikes with a 3.5 kg warhead and a 30 km range.
The ST-35 Silent Thunder is a loitering munition unmanned aerial vehicle (UAV) developed by Ukrainian company Athlon Avia. It features a vertical takeoff facilitated by a multirotor system and transitions to fixed-wing flight for target engagement. The UAV has a takeoff weight of 9.5 kilograms (20.9 pounds) and carries a 3.5-kilogram (7.7-pound) warhead. It operates within a 30-kilometer (18.6-mile) range, cruising at speeds between 120 to 140 kilometers per hour (74.6 to 87 miles per hour) at altitudes of 800 to 1,200 meters (2,625 to 3,937 feet). The system employs automatic targeting via television or infrared channels and boasts a 95% probability of hitting targets with a circular deviation of up to 3 meters (9.8 feet). Designed for portability, the system can be carried by personnel in backpacks, with each unit weighing approximately 15 kilograms (33 pounds).
History of the Development of the Athlon-Avia ST-35 Silent Thunder
In the late 2010s, the landscape of modern warfare was rapidly evolving, with an increasing emphasis on precision strikes and minimizing collateral damage. Traditional munitions often lacked the flexibility to engage time-sensitive or concealed targets effectively. This gap highlighted the need for loitering munitions—systems capable of lingering over a battlefield, identifying targets, and striking with high precision.
Athlon Avia, a Ukrainian company established in 2013, recognized this emerging requirement. Leveraging their experience in developing unmanned aerial systems, they initiated the development of the ST-35 Silent Thunder loitering munition. The objective was to create a UAV that could autonomously locate and engage high-value targets, such as radar installations, electronic warfare systems, and command centers, while reducing the risk to personnel and non-combatants.
The development program commenced in the late 2010s, with a focus on integrating modern technological solutions to enhance operational capabilities and reduce detectability. The design team aimed to achieve a balance between portability, endurance, and payload capacity. The ST-35 was designed to be carried by small units, allowing for rapid deployment in various combat scenarios.
The ST-35 Silent Thunder was publicly unveiled in October 2019. Following its introduction, the UAV underwent a series of guided flight trials to validate its design and performance parameters. Initial guided flight trials were concluded in March 2020, followed by evaluations in various operational modes in April 2020. These tests assessed the UAV’s flight stability, targeting accuracy, and overall system reliability.
In October 2020, the ST-35 was demonstrated during training camps for UAV specialists and counter-UAV operations in Ukraine. This demonstration showcased its capabilities in a realistic operational environment, highlighting its potential effectiveness in modern combat scenarios.
The ST-35 Silent Thunder does not have a NATO reporting name, as it is not a standard NATO-designated system.
The development of the ST-35 reflects a broader trend in military technology towards autonomous systems that can perform precision strikes with minimal human intervention. Its creation was driven by the need for a munition that could loiter over a target area, conduct surveillance, and engage targets that are either time-sensitive or concealed. The ST-35’s development aligns with Ukraine’s strategic focus on enhancing its indigenous defense capabilities, particularly in response to evolving regional security challenges.
Athlon Avia’s initiative in developing the ST-35 demonstrates the company’s commitment to advancing unmanned systems technology. By focusing on loitering munitions, they have addressed a critical capability gap in modern warfare, providing armed forces with a tool that enhances both strategic flexibility and operational effectiveness.
Design of the Athlon-Avia ST-35 Silent Thunder
The ST-35 Silent Thunder features a distinctive design that integrates both multirotor and fixed-wing flight characteristics. This hybrid approach allows for vertical takeoff and landing (VTOL) capabilities, combined with efficient horizontal flight for target engagement.
The UAV’s airframe is constructed from lightweight composite materials, contributing to its overall takeoff weight of 9.5 kilograms (20.9 pounds). The fuselage measures approximately 300 millimeters (11.8 inches) in length and 90 millimeters (3.5 inches) in width, resulting in a compact and portable form factor. The design incorporates an X-layout biplane wing configuration, which enhances aerodynamic stability and maneuverability during flight.
For vertical takeoff, the ST-35 utilizes a multirotor system comprising multiple rotors arranged around the fuselage. This configuration enables the UAV to ascend to a predetermined altitude, typically between 400 to 600 meters (1,312 to 1,969 feet), before transitioning to horizontal flight. Upon reaching the desired altitude, the multirotor assembly detaches, and the UAV continues in fixed-wing mode, propelled by a rear-mounted pusher propeller. This transition allows for efficient cruising at speeds between 120 to 140 kilometers per hour (74.6 to 87 miles per hour).
The ST-35 Silent Thunder’s warhead, weighing 3.5 kilograms (7.7 pounds), is housed in the nose section. The UAV can be equipped with various warhead types, including high-explosive anti-tank (HEAT), fuel-air explosive (FAE), and high-explosive fragmentation (HEF), allowing it to engage a range of target types effectively.
The guidance system employs semi-automatic control using interchangeable television and infrared (IR) channels, enabling effective target acquisition in diverse visibility and weather conditions. This flexibility ensures that the UAV can operate effectively in various operational environments.
The launch process involves deploying the UAV vertically to an altitude of 400 to 600 meters (1,312 to 1,969 feet) using the multirotor system. Upon reaching the desired altitude, the loitering munition detaches from the multirotor platform and transitions to horizontal flight towards the target. The multirotor platform then returns to the launch site and can be used for subsequent missions.
The ground control station (GCS) is responsible for mission planning, launch control, and in-flight monitoring. Operators can select targets, monitor the UAV’s flight path, and make real-time adjustments as needed. The system’s design emphasizes portability, with components that can be disassembled and transported by personnel, facilitating rapid deployment in various operational settings.
Performance of the Athlon-Avia ST-35 Silent Thunder
The ST-35 Silent Thunder is powered by an electric motor that drives a rear-mounted pusher propeller during horizontal flight. This propulsion system enables the UAV to achieve a cruise speed ranging from 120 to 140 kilometers per hour (74.6 to 87 miles per hour). The electric motor offers the advantages of reduced acoustic signature and lower thermal emissions, enhancing the UAV’s stealth characteristics.
The UAV operates effectively at altitudes between 800 to 1,200 meters (2,625 to 3,937 feet), allowing it to remain above small arms fire while maintaining a vantage point for target acquisition. Its operational range is approximately 30 kilometers (18.6 miles), with an endurance of up to 60 minutes, providing sufficient time to loiter over target areas and engage as opportunities arise.
The guidance system utilizes semi-automatic control with options for television and infrared channels, allowing operators to select the most appropriate sensor based on environmental conditions. This flexibility ensures effective target acquisition and engagement across a range of scenarios.
The warhead, weighing 3.5 kilograms (7.7 pounds), can be configured with different types of munitions, including high-explosive anti-tank (HEAT), fuel-air explosive (FAE), and high-explosive fragmentation (HEF). This versatility allows the ST-35 to effectively engage a variety of targets, from armored vehicles to fortified positions.
In terms of accuracy, the ST-35 boasts a circular error probable (CEP) of up to 3 meters (9.8 feet), resulting in a 95% probability of hitting the intended target. This high level of precision minimizes collateral damage, making the UAV suitable for operations in complex environments, including urban areas.
When compared to other loitering munitions, the ST-35’s performance parameters position it as a capable system within its class. For instance, the Israeli Harop loitering munition has a longer endurance and range but is significantly larger and more complex to deploy. The ST-35’s combination of portability, ease of use, and precision makes it a valuable asset for forces requiring rapid deployment and flexible engagement options.
In summary, the ST-35 Silent Thunder offers a balanced performance profile, combining sufficient speed, range, and endurance with high precision and versatile payload options, making it well-suited for a variety of tactical scenarios.
Variants of the Athlon-Avia ST-35 Silent Thunder
As of now, the ST-35 Silent Thunder is primarily offered in its standard configuration. However, the system’s modular design allows for adaptability to meet specific mission requirements.
- Standard Variant: Equipped with a 3.5-kilogram (7.7-pound) warhead, this version is designed for general-purpose missions, capable of engaging a variety of targets with high precision.
- Customized Payloads: Athlon Avia has indicated the potential for integrating different types of warheads, such as high-explosive anti-tank (HEAT), fuel-air explosive (FAE), and high-explosive fragmentation (HEF), to tailor the UAV for specific target sets.
- Enhanced Guidance Systems: Depending on operational needs, the guidance system can be configured with either television or infrared channels, allowing for flexibility in various environmental conditions.
While these configurations are not distinct variants with separate designations, they demonstrate the ST-35’s adaptability to different operational scenarios. Future developments may lead to more specialized versions as operational feedback and technological advancements inform design iterations.
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