Russia’s Sukhoi design bureau unveiled two big surprise UAV concepts during Army 2024: an autonomous logistics drone designated S-76, capable of transporting 300 kg to a range of 1000 km, and an air-launched stealthy combat UAV designated S-71.
Both UAVs are impressive out-of-the-box concepts, but in view of Russia’s ongoing special military operation in Ukraine, the S-71 hogs attention because—not only is it deadly, but Sukhoi officials told Aviation Week that the RuMoD (Russian Defense Ministry) has already given it a production go-ahead!
S-71 Honed by Battlefield Experience In Ukraine
Sukhoi initiated the development of the S-71 UAV to meet RuMoD specifications drafted in 2019, which emphasized multi-mission capability. However, along the way, Sukhoi tweaked the specification to increase range and reduce the drone’s radar cross-section.
Russia’s experience in Ukraine has emphasized the need for 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 center 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 to destroy moving targets!
The drone, which is optimized 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-sized turbofan engine TRDD-50 with a recessed ventral rear air intake. This engine is also used in the cruise missiles Kh-59M and Kh-101. The drone is capable of reaching a speed of about 0.6 Mach and rising to a maximum altitude of up to 8 thousand meters.
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 charges) 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 targeting data stored onboard. An operator can remain in the loop to validate the UAV-selected target or guide the weapon to its aim point.
According to the Aviation Week report, 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.
If the S-71K cannot be carried externally, it’s likely a larger and heavier missile with a modular design. The larger size 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 S-71M as an air-launched UAV, not a cruise missile, suggests that the drone’s advanced autonomous capabilities allow it to return to its launch point or another designated location after completing its mission.
Operational Role Analysis
Since the RuMoD has cleared production of the S-71, it’s likely to be operationally deployed in Ukraine over the next few months. The following is a brief analysis aimed at identifying the weapon’s outstanding features and its likely impact on the ongoing conflict.
The S-71 apparently has the capability to navigate to the target area, find its target, and strike it without relying on SATNAV or a datalink, which makes the missile unstoppable. (SATNAV can be jammed, and datalink transmission can be detected using ELINT and jammed using EW.)
Since the S-71M supports operator-in-loop operation, it does have a data link, but it can also revert to autonomous operation in the event of a data link loss.
Stealth Advantage
The weapon system’s stealth design will allow it to cruise at higher altitudes, thereby maximizing range. Non-stealthy cruise missiles like the Russian Kalibr 3M-14 have to fly low, hugging the terrain to avoid radar detection. Such a flight profile significantly reduces the missile’s range because of higher fuel consumption at very low altitudes and the need to continuously avoid terrain.
The S-71’s electro-optical sensors are capable of operating day and night (Optical / Thermal Imaging). The drone likely uses optical guidance and target recognition technology developed for Lancet drones and Izdeliye 305 multipurpose guided missiles.
The S-71 can fly to the target area using passive INS (Inertial Navigation System), use its electro-optical sensors to fix its ground position, fly towards a target that may well be moving, and designate the target for attack by an Iskander-M or a SALH (semi-active laser homing) weapon carried by a Su-57 in its internal weapons bay or from any other aircraft.
According to the Aviation Week report, Sukhoi’s chief test pilot, Sergei Bogdan, performed the first flight carrying S-71K and S-71M drones externally under the wing of the Su-57.
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External carriage of the S-71K would make the Su-57 non-stealthy. A Su-57 would carry an external weapon load only if the target was known and the use of the externally carried weapon was pre-planned.
It’s conceivable that the two S-71 variants are capable of a two-missile swarm attack. Both missiles could be launched simultaneously at a target. Upon arriving at the target area, the S-71M could identify and designate the target for strike by the S-71K missile. The S-71M could then return to base or its recovery point.
A return to base use of the S-71M would cut the operating range of the UAV to half.
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Conclusion
The S-71M drone effectively extends the range of stealth fighters deep into layered, air defence-protected airspace without risking pilot life.
The simultaneous use of two variants—one to locate, identify, and designate the target and the other to destroy it with the right warhead—will reduce costs and make the weapon system affordable for widespread use.
Sukhoi is reportedly producing the control and guidance systems in-house, indicating zero dependence on imported components, including microprocessors and other semiconductors.
The combination of S-71K and S-71M variants, externally carried and launched from non-stealthy platforms like the Su-34, would be ideally suited to hunting and destroying adversary AD (air defense) systems deployed along the battlefront. Following such an attack, the S-71M would be recovered and reused repeatedly.
For deep search and destroy strikes on targets, such as F-16s returning to base after a mission, the S-71M variant could be used stand-alone on a one-way mission.
The large size of Russian fighters gives them the ability to carry large missiles with long range. The S-71 will have a range and target detection capability that will allow Ukrainian F-16s to run but not hide in the distant interiors of the country.
- Vijainder K Thakur is a retired IAF Jaguar pilot, author, software architect, entrepreneur, and military analyst.
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