Although the ST-35 Silent Thunder was unveiled in October 2019, a guided flight test period followed until April 2020, and it is likely that the system would be fully operational in October of that same year. This system consists of a multi-rotor system, a dropping module, a relay module, an antenna system, a ground control tablet, the UAV (munition), vision modules for the munition, warheads and a kit of spare parts and tools. This system immediately entered service with the Ukrainian Forces and is being used in combat against the invading Russian forces.The multi-rotor has a built-in transponder and is responsible for raising the ammunition to a height of about 600 meters, where it is released to start the flight to the assigned area. Afterwards, the multi-rotor returns to ground where the operator replaces the dropping module with the relay module with antennas. It is then sent back to a height of about 1,000 meters where it sends the operator signals to the munition as it heads to the target. Once the target has been attacked, the multi-rotor returns to ground and the mission is over.The single use ammunition of the ST-35 system is like a small missile with 4 cruciform wings in the middle of the casing with 4 cruciform tailplanes. On the nose it has a vision module with an automatic guidance system via TV or IR. Inside the rear of the casing is a small motor that drives a two bladed propeller. The ammunition flies at a maximum speed of about 140 km/h at a maximum distance of 30 km. The operating altitude is between 800 and 1,200 meters and can remain airborne for 60 minutes before launching towards the target.ST-35 Silent Thunder weighs 9.5kg and has 3 different types of warhead depending on the mission to be carried out. Each warhead weighs 3.5 kg and is of the fuel-air explosive (FAE), high-explosive anti-tank (HEAT) and high-explosive fragmentation (HEF) type. This loitering munition has a silent mode of use that makes it particularly difficult to detect, and this, together with its flight altitude and its small size, means that the possibility of hitting its target is 95%, according to the manufacturer’s tests. Its circular error probability (CEP) is a maximum of 3 meters, which makes it a very accurate weapon.The system is designed to be carried in three backpacks weighing 16.4, 16.9 and 17.2 kg each, including 3 loitering munitions. In addition, there is a portable variant of the Silent Thunder that can be transported in light vehicles and consists of 8 munitions that are launched from the transport vehicle itself by installing a small lifting platform that also allows the recovery of the multi-rotor vehicle. This version offers great flexibility of use and provides infantry units with the ability to carry out highly precise selective attacks.The mission sequence of the ST-35 system is developed as follows: – the UAV (loitering munition), the launch platform and the antenna system are assembled and connected – the multi-rotor loaded with the UAV is launched into the air up to about 600 meters in height, – the UAV is released, – the launch platform returns to the ground where the relay module with antennas is installed, – the multi-rotor is raised again up to 1,000 meters in height for the operator to transmit the commands to the UAV, – the operator chooses the target and confirms it to the UAV, – the UAV begins its autonomous operations towards the target, – the UAV engages and destroys the target and the operator confirms it visually, – the multi-rotor returns to the launch site, -components are disassembled and saved, -mission completed.
