The ST-35 Silent Thunder loitering munition can explore and engage enemy targets. Image courtesy of Athlon Avia.
The loitering munition has a cruise speed ranging between 120km/h and 140km/h. Image courtesy of Athlon Avia.
ST-35 Silent Thunder was unveiled in October 2019. Image courtesy of Athlon Avia.
ST-35 Silent Thunder can carry different types of warheads such as high explosive, thermobaric, cumulative, and incendiary. Credit: Athlon Avia.

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The ST-35 Silent Thunder is a loitering munition developed by Athlon Avia, an unmanned aircraft systems manufacturer based in Ukraine.

The precision-guided weapon system can destroy the enemy targets with minimal risk to people and infrastructure around the targets.

It can be deployed to target radar stations, command posts, as well as command and control platforms. It is capable of defeating particularly important and valuable targets in closed positions.

Athlon Avia unveiled the new model of a single-use drone in October 2019. The loitering munition was built for use by the Ukrainian Armed Forces.

The company concluded the initial series of guided flight trials in March 2020. The ST-35 Silent Thunder was evaluated at different modes during the next stage of testing conducted in April 2020.

The loitering munition was demonstrated as part of training camps for unmanned aerial vehicle (UAV) specialists and UAV countermeasures in Ukraine in October 2020.

It was also demonstrated along with Athlon Avia’s A1-CM Furia UAV at the XVII International Specialized Exhibition – Arms and Security 2021 at the International Exhibition Centre in Kyiv, Ukraine, in June 2021.

ST-35 Silent Thunder design and features

The ST-35 Silent Thunder features a multi-copter design integrating a transponder and a single-use munition. It incorporates an X-layout biplane scheme, which ensures accuracy during horizontal flight and vertical trajectory for precision target attack.

The probability of loitering munition hitting the target is approximately 95% while circular deviation is up to 3m.

The weapon system is complemented by a ground control station, optical payload, warhead, multi-rotor, dropping module, relay module, antenna complex, as well as spare parts, tools, and equipment.

The loitering munition is guided semi-automatically using television or infrared (IR) guidance heads which can be swapped based on visibility and weather conditions.

The fast-moving target ensures quiet and unnoticeable operation. It can be operated in silent mode and at an altitude of 1,200m, making it a difficult target to detect.

The length and width of the weapon are 300mm and 90mm respectively while its take-off weight is 9.5kg.

The ST-35 single-use drone employs a human operator for locating targets and can perform autonomous flight after launch. It can assess weather conditions, approach the aiming point, and dive at the target while operating autonomously.

A portable version of the weapon system includes three munition sets and multi-rotor modules for 16 launches. An automatic lifting and starting platform is also part of the portable model.

Deployment and launch of ST-35 Silent Thunder

The fuselage of the ST-35 loitering munition is fixed after the deployment of the launch platform. The payload module and the optical section are connected to the fuselage while the dropping module, central section, and multi-rotor assembly are hinged to launch the loitering munition.

The pre-flight systems are checked and the aerial system is vertically launched to an altitude of 400 to 600m, where the loitering munition gets undocked from the multi-rotor platform to ensure horizontal flight towards the target.

The multi-rotor platform returns to the launch pad after undocking. It is attached with the relay module with antennas and is flown to an altitude of 1,000m to support the relay of signals between the loitering munition and operator.

The aerial system conducts pre-intelligence procedures that enable the operator to detect the target. Target destruction is confirmed upon visual confirmation from the operator.

Warheads of the ST-35 Silent Thunder

ST-35 Silent Thunder can be armed with different types of warheads such as high explosive, thermobaric, cumulative, and incendiary. It can also carry high-explosive anti-tank (HEAT), fuel-air explosive (FAE), and high-explosive fragmentation (HEF) warheads weighing up to 3.5kg each.

Athlon Avia also intends to develop a shaped charge warhead to avoid collateral damage during high-risk missions.

ST-35 Silent Thunder performance

The ST-35 Silent Thunder loitering weapon has a cruise speed ranging between 120km/h and 140km/h. It has an operational range of 30km.

The loitering munition can be deployed in 15 to 20 minutes. It can remain airborne for up to 60 minutes.