The Sukhoi Design Bureau is forging a lethal, collaborative-drone arsenal to multiply the reach and lethality of the Su-57 “Felon,” pushing the Russian stealth fighter well beyond the mission envelope of contemporary U.S. and Chinese stealth fighters.
The suite includes independently operating loyal-wingman drones that taxi, take off, and land autonomously; an autonomous internal-bay UAV designed to launch from the Felon, strike, and return autonomously; and externally carried, expendable attack drones that can be guided to the target or launched as cruise missiles.
Most importantly, the combat drones that Sukhoi is developing for collaborative combat are based on peer-to-peer combat experience.
Sukhoi’s Vision
TASS quotes Mikhail Strelets, the first deputy director and managing director of Sukhoi, as saying that tactical aviation must transition from a collection of individual high-tech aircraft to integrated aviation systems.
“Countering multi-layered air-defence systems with manned aircraft alone has become prohibitively expensive. Therefore, the focus is shifting toward a network of functional complexes, each designed to address specific targets and tasks.
“Currently, we are working on approximately eight different UAV variants,” Strelets stated.
Knowledge of some of the combat drones that the Sukhoi Design Bureau is developing is in the public domain.
These include:
- S-70 Okhotnik Low Observable Collaborative Combat Aircraft (CCA)
- S-71M “Monochrome” advanced autonomous drone designed for internal carriage by a Su-57
- S-71K expendable, externally carried variant attack drone or cruise missile
Okhotnik
The Okhotnik (Hunter) is a heavy (20–22 t) autonomous UCAV reportedly capable of speeds of around 1,000 km/h. It features a flying wing design and is powered by a single engine, most likely the AL-41F.
The drone features a flying wing scheme with a three-column chassis. The Skat drone developed by MiG in the 1990s was also based on a flying wing design, and it is possible that some Skat technologies may be used in the Okhotnik. The drone, which features a shaped engine exhaust, has better stealth characteristics than the Su-57.
Based on analysis of public-domain photos by specialists, in 2019, Pravda reported that the Okhotnik is equipped with a state-of-the-art multi-function radar with an active phased-array antenna.
Low-rate initial production of the drone, which has participated in combat missions in Ukraine, is underway. Ukraine’s Intelligence Directorate reports that Okhotniks have undertaken reconnaissance flights in Ukrainian airspace since July 2023.
On 5 October 2024, a Su-57 engaged and shot down an S-70 “Okhotnik” UCAV during operations close to the frontline, destroying the drone before it could complete its mission.
The reasons for the shootdown, the exact weapons used, the location, and the timing vary between sources and remain unconfirmed.
The drone is close to operational induction. United Aircraft Corporation’s Yuri Slyusar told the press in August 2023 that pilot production of S-70 drones is currently underway. At present, two S-70 drones are undergoing flight testing.
S-71 Drone
Russia’s Sukhoi Design Bureau unveiled two big surprise UAV concepts during Army 2024: an autonomous logistics drone designated S-76 that is capable of transporting 300 kg to a range of 1,000 km, and an air-launched stealthy combat UAV designated S-71.
It is likely that the S-76 logistics drone is among the eight drones that Mikhail Strelets alluded to. However, in this article, we will focus only on combat drones.
Sukhoi initiated development of the S-71 UAV to meet RuMoD specifications drafted in 2019, which emphasised multi-mission capability.
However, based on operational experience, Sukhoi tweaked the specification to increase range and reduce the radar cross-section of the drone. Russia’s experience in Ukraine has emphasised the need for a greater range and increased survivability. The intensity of the conflict additionally emphasized scalability through reduced production costs.
The S-71 began captive-carry trials in April 2024 at Russia’s flight research centre in Zhukovsky, with test flights involving the Su-57 fighter.
In its present incarnation, the S-71 is an air-launched UAV that can be tasked with location, identification, and designation for the destruction of moving targets.
The drone, which is optimised for radar stealth, features a trapezoidal fuselage similar to the Storm Shadow, folding wings, and an inverted V-shaped tail.
It is powered by a small turbofan engine, the TRDD-50, with a recessed ventral rear air intake. This engine is also used in the Kh-59M and Kh-101 cruise missiles. The drone is capable of reaching a speed of about Mach 0.6 and rising to a maximum altitude of up to 8,000 metres.
S-71 Variants
There are two variants of the drone: S-71M Monochrome and S-71K Carpet.
The S-71K performs the role of an air-to-surface cruise missile that can be guided to its target. It features a modular (cluster, high-explosive, and shaped-charge) warhead, likely with electro-optical or SALH (Semi-Active Laser Homing) guidance for target acquisition.
The S-71M performs a more advanced role. It can autonomously search, detect, and engage moving targets using electro-optical sensors and store targeting data onboard. An operator can remain in the loop to validate the UAV-selected target or guide the weapon to its aim point.
According to Aviation Week, the S-71K is carried externally by its launch aircraft, while the S-71M can also be carried externally or housed in the weapons bay of a Su-57 or S-70 Okhotnik UAV.
Since it cannot be carried internally, the S-71K is likely a larger and heavier missile with a modular design. The larger size of the S-71K may have been necessitated by the need to carry submunitions warheads.
The S-71M is restricted to carrying high-explosive and shaped-charge warheads.
The classification of the S-71M as an air-launched UAV, not a cruise missile, suggests that the advanced autonomous capabilities of the drone allow it to return to its launch point or another designated location after completing its mission.
Despite speculation, the operational use of S-71 drones has not been confirmed.
Conclusion
True to form, Russia has adopted a low-cost, evolutionary approach to future-proofing its aerial combat capabilities.
Instead of developing manned systems to operate in contested airspace, it is focusing on unmanned stealth platforms that can penetrate deep into adversary territory, extending the reach of fighters like the Su-57, which can remain safely closer to the frontline.
The S-70 CCA and the S-71M stealth drone effectively extend the range of the Su-57 deep into layered air-defence-protected airspace without putting a pilot at risk.
A Su-57 can launch an S-71M to locate, identify, and designate the target, and the S-71K can then be launched by a non-stealthy fighter such as a Su-34 to destroy the target using the appropriate warhead.
The operational paradigm makes deep-strike capability affordable. This is relevant for India, which is considering the acquisition of the Su-57.
- Vijainder K Thakur is a retired IAF Jaguar pilot, author, software architect, entrepreneur, and military analyst.
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