Meet the Sukhoi S-70: Russia's New and Deadly Stealth Drone
A big deal?
Key point: Russia's S-70 Okhotnik looks promising and is similar to America's stealth planes. However, major adjustments are needed to ensure the S-70 is actually as stealthy as it is supposed to be.
On August 7, 2019 the Russian Ministry of Defense released a video showing the first flight, five days earlier, of a prototype stealth drone called Sukhoi S-70 Okhotnik-B. The flying-wing drone circled for twenty minutes around two thousand feet above the Chkalov State Flight Test Center in Astrakhan (near the Caspian Sea) before coming down for a landing.
Okhotnik, which means “Hunter,” is a large flying-wing style Unmanned Combat Air Vehicle, or a “Strike Reconnaissance Unmanned Complex” in Russian nomenclature. That means it’s a low-observable drone that can launch deadly attacks as well as serve in a surveillance and electronic warfare role.
While development of the Okhotnik began in 2011, the vehicle first emerged into public view on January 23 in photos on Russian social media of one of the flying drones being towed by a tractor at Novosibirsk, Siberia.
Then on May 14, the Okhotnik was photographed at the Chkalov facility during a visit by President Vladimir Putin. While Putin then primarily flaunted the capabilities of the Su-57 stealth fighter, which is entering wider-scale production, he also alluded to the capabilities of the stealth drone.
Satellite photos revealed that the drone, when compared to nearby parked Flanker jets, is fairly large with wings roughly 19-meters wide. According to Jane’s, it weighs a hefty 20 tons and its maximum speed is in the high subsonic range. The drone’s capacious fuselage has two internal bays with a capacity for over two tons of weapons or specialized equipment, and supposedly enough fuel to give the drone a range exceeding 3,700 miles. The UCAV reportedly incorporates composite surfaces coated with radar-absorbent materials to minimize its radar cross-section.
The Russian UAV‘s flying-wing configuration and fuselage embedded engine bear more than a passing resemblance to the U.S. Air Force’s RQ-170 stealth drone, the existence of which only became publicly acknowledged after one was captured by Iran via hacking and then extensively studied by Russia.
Tailless flying wing aircraft tend to be aerodynamically unstable, and only truly became viable with the development of computerized fly-by-wire control systems to automatically compensate for that instability. This first flight was thus surely primarily to test the airworthiness of the drone and its flight control systems. Previously, the Okhotnik reportedly performed taxi tests and also a short “jump-and-land” in which it flew for a few brief seconds before settling back down on its three landing gears.
While the Okhotnik was remotely controlled by a human pilot for August 2 test, Russia Beyond claimed the ‘fully robotized’ aircraft would be able to fly autonomously under operational circumstances—meaning instead of being under direct remote control by a human operator, it would use an onboard AI to dynamically react to changing circumstances and execute its pre-programmed mission. That way, the Okhotnik won’t have to maintain a jammable or hackable command link to a human pilot over long distances.
However, fellow TNI writer David Axe points out that the autonomous system may pose an even bigger technical challenge than designing a stealthy airframe:
“What's hard, when it comes to deploying fast armed drones to meaningful military effect, are the communications, control systems and computer algorithms—and the techniques and tactics for operating unmanned aerial vehicles over long distances in crowded airspace alongside manned aircraft and other forces.”
Stealth Drones and the INF
It may not be entirely coincidental that Okhotnik’s first flight on August 2, 2019 took place on the same day that marked the final demise of the Intermediate Nuclear Force treaty.
While the Trump administration cited Russia’s violation of the treaty by installing long-range cruise missiles on an Iskander-K missile truck, Moscow has complained in return that the Pentagon’s many long-range drones should count as “cruise missiles,” and thus should have been banned under INF too.
While the U.S. Air Force’s Reaper UCAVs are not designed for stealth, Russia may be paranoid that stealthy surveillance drones like the RQ-170—or the even more obscure long-endurance RQ-180—could be converted to perform deadly surprise attacks.
That Moscow has not cloaked the project in greater secrecy may reflect that it wants the drone to signal to both domestic and foreign observers that it can develop the capability to launch the same sort of stealthy, penetrating attacks it fears coming from the United States.
However, Russian boasts about the Okhotnik’s invisibility do not appear entirely merited. The inlet and exhaust nozzle of its dorsally-mounted AL-31F turbofan—similar to that found on the Su-57 stealth fighter—are visibly unoptimized for radar or even thermal stealth. This means the Okhotnik-B will be particularly vulnerable to detection when scanned from its rear aspect.
While this problem is also evident in the Su-57 stealth fighter, it’s a bigger issue for a drone designed to penetrate enemy airspace (as it will fly past enemy radars and patrol planes, and thus get scanned from the side and rear) then for a fighter designed for hit-and-run attacks.
The Okhotnik’s two-ton payload is also not particularly large. While Professor Vadim Kozyulin told Russia Beyond the drone would lug unguided fragmentation bombs and fuel-air explosives, the small payload would suggest it would either have to carry nuclear or precision-guided missiles in order to guarantee its attacks can achieve significant destructive effects. This concept would actually be similar to the U.S. Air Force’s first stealth jet, the F-117 Nighthawk, which was designed to carry just two 2,000-pound laser-guided bombs to hit a small number of targets with a high degree of precision.
Both The Drive’s Joseph Trevithick and Michael Kofman of the Center of Naval Analysis have speculated the S-70 might be intended to serve as a “loyal wingman” type drone—basically one or two UCAVs networked with a manned fighter (such as an Su-57), serving as foxhound-like outriders to perform risky attacks and employ indiscrete sensors, while the manned jet remains safe from retaliation. Indeed, some Russian unit markings hint that the Okhotnik may be intended to pair up with Su-57 stealth fighters.
While initially emphasizing the Okhotnik’s strike role, Russian media more recently has described it has a long-endurance surveillance and electronic warfare platform. In the latter role, it could creep into enemy airspace and jam adversary’s radar and communication signals—opening a “breach” for missiles or manned aircraft to penetrate.
The Okhotnik’s effectiveness for deep penetration missions will depend on whether Russian engineers attempt to significantly refine the airframe with a more discreet engine configuration, perhaps incorporating a shrouded or S-shaped inlet. But even with only low-grade stealth, the S-70 could give Russia a useful tool for fast-reacting long-endurance reconnaissance and strike capabilities—which the Russian military reportedly lacked in its expeditionary air campaign bombarding Syrian rebels.
Of course, the Hunter’s success also will depend on Moscow’s ability to continually finance it development, and production—not something to take for granted when other major Russian defense programs have repeatedly fallen far behind schedule.
Sébastien Roblin holds a Master’s Degree in Conflict Resolution from Georgetown University and served as a university instructor for the Peace Corps in China. He has also worked in education, editing, and refugee resettlement in France and the United States. He currently writes on security and military history for War Is Boring. This first appeared in August 2019.
Image: Russian Ministry of Defense.