Russian Military Enhances UACV Strike Capability

The leadership of Russia’s Armed Forces has used the introduction and diversification of unmanned aerial vehicles (UAV) as a means to boost target acquisition in combat operations. The role of both UAVs and unmanned aerial combat vehicles (UACV) in Russian military planning is extending into developing such systems for conducting strikes. A key example of this technological process is the effort to combine the Su-57 fifth-generation fighter with the heavy-strike UCAV S-70 Okhotnik (“Hunter”), first publicly seen in early 2019 and which underwent its first test flight in August of that year (see EDM, November 19, 2019). The Okhotnik remains at its testing stage, yet advances in its design suggest it will offer a formidable strike capability for the Aerospace Forces (Vozdushno Kosmicheskikh Sil—VKS) (Rossiyskaya Gazeta, October 10, 2021).

The reported development of the Su-57 focuses on its strike potential. It differs from the United States Air Force (USAF) F-22 and China’s People’s Liberation Army Air Force (PLAAF) J-20 since it is designed to be much more versatile, less focused on gaining air superiority, and with greater ability to engage ground and sea-based targets. The Su-57 will have an array of weapons systems at its disposal. In particular, the PBK-500U Drel allows the Su-57 to strike ground targets at a distance of 30–50 kilometers based on the “fire and forget” principle. The GLONASS-guided cluster glide bombs use inertial and satellite guidance for maximum accuracy. Long-range strike for the Su-57 involves the use of Kh-59MK2 cruise missiles with a warhead weighing 320 kilograms. These can destroy targets at a distance of up to 285 kilometers. In 2018, these cruise missiles were used in Syria to strike bunkers and underground facilities. The evolution of the Kh-59MK family of cruise missiles pose a potential threat to surface ships. The Su-57 can also carry Kh-58 missiles to neutralize enemy radars and air-defense targets from distances of more than 150 km. Moreover, the Su-57 benefits from ongoing development of hypersonic missile systems, including the miniature version of the Kinzhal hypersonic missile. The Kinzhal missile is believed to have a strike range of more than 1,000 kilometers, leading Russian military specialists to conclude that the Su-57 is ideal for targeting adversary surface ships (Topwar.ru, October 19; Vpk-news.ru, October 18).

Russia’s defense ministry also plans a single-seat version of the Su-57, as part of the Megapolis development work expected to begin production in 2025. A defense industry source explained to Russian media, “The updated version of the fighter within the framework of the Megapolis will be equipped with a completely renewed cockpit with the most advanced avionics. In addition, the aircraft will be equipped with a second-stage engine. It is planned that from 2025, the modernized Su-57 should begin to be mass produced.” The two-seater Su-57 is also being developed to control and operate in tandem with the S-70 Okhotnik heavy-strike UACV (Rossiyskaya Gazeta, October 18; Vpk-news.ru, August 9).

The S-70 Okhotnik, developed by Sukhoi, is considered to be the main hope for Russian strike aviation. The defense ministry regularly releases video footage of the combat drone’s tests, and those trials are regularly reported on in the Russian media, with some of the Okhotnik’s specifications carefully qualified through these outlets (see EDM, November 13, 2020). Recently, Russian military media released new details of the effort to enhance the stealth features in the Okhotnik’s design. This relates to the fitting of stealth nozzles to the UACV’s single engine (Topwar.ru, October 19).

In relation to the stealth nozzle, the layout is new for domestic aviation and clearly differs from the first prototype. Unlike the commonplace round nozzles, the Okhotnik will use a rectangular (flat) nozzle. Heretofore, this design feature was not used in Russian aviation, but it has been notably implemented in the USAF F-22 and the supersonic heavy stealth strategic bomber B-2 Spirit, produced by Northrop. The flat nozzle design makes it possible to increase the stealthiness of an aircraft’s signature, thus hopefully boosting its survivability. According to Sergei Kuzmin, a deputy general designer at the Motor Design Bureau, the S-70 Okhotnik’s new prototype will receive a flat nozzle, providing the advanced strike UACV with more reduced visibility. According to Kuzmin, the innovation allows for more efficient dissipation of the heat trace from the engine. Consequently, the Okhotnik will be less vulnerable to guided missiles with infrared and thermal homing heads (Topwar.ru, October 19).

Kuzmin emphasized that the introduction of such a nozzle shape has been a global trend since the end of the 20^th century. According to the designer, the new flat nozzle, developed in Ufa, will be almost completely hidden in the design of the S-70 Okhotnik UACV, reducing the visible flame from its engine, effectively dissipating it. For additional camouflage to protect against guided missiles, the developers will cover the hot parts of the engine with cold elements while constructing the inner part of the nozzle. Due to the cover of the nozzle being part of the airframe design, the radar signature of the aircraft is also reduced. Kuzmin stated that the nozzle for the Okhotnik is assembled using additive technology, in which parts and structural elements are produced on a 3D printer, after which they are assembled and tested using more than 200 different sensors (Topwar.ru, October 19).

A version of the AL-41F1 engine for the Su-57 is installed on the Okhotnik. The UACV has only one engine, which imposes special requirements for its reliability. The applied systems allow its engine to work even in the event of a complete failure of its automation—it will simply go to idle speed, according to Sergei Vakushin, the chief designer of UEC-UMPO for products at the P. Lyul’ki Design Bureau (Rossiyskaya Gazeta, October 10). The idea of developing a rectangular (flat) nozzle was studied at the Motor enterprise in Ufa in the early 1990s and was tested at that time in one of the Su-27UB fighter engines. The nozzle had the ability to change the direction of the thrust vector. Yet despite promising tests results based on approximately twenty experimental flights, which confirmed a reduction in the signature of the engine, lack of funding in the 1990s resulted in a suspension of further work (Topwar.ru, October 19). In contrast, today, enhancing the stealth capability of the Okhotnik UACV appears to be a high priority ahead of this weapons system’s procurement by the VKS.