Russian Report Explains Why Air Defenses Cannot Shoot Down Drones

Small drones have been a big headache for both sides in this conflict, but especially for the Russians. It is not just that they are destroying tanks and other vehicles; day after day videos on social media show Ukrainian drones stalking the Russian air defence systems that are supposed to be shooting them down and bombing or directing precision artillery fire onto them.

This should not have come as a surprise. In 2020 a detailed Russian report warned that “… we can conclude that modern [Russian] air defense systems are very poorly adapted to combat UAVs [Uncrewed Air Vehicles, drones].”

Why are they so bad at hitting drones in particular?

Early Warning

Prof Sergey Makarenko of St. Petersburg Electrotechnical University “LETI” authored the 193-page report entitled Countering Unmanned Air Vehicles. Makaranko studies military applications of technology, and this is one of the few open-source documents giving an insider analysis of Russian anti-drone capability.

Unlike the U.S. which relies more on air cover, Russia has always provided armored formations with generous numbers of tactical anti-aircraft vehicles. The Russian army is now equipped a variety of systems including the Panstsir S1 which combines guns and missiles on a heavy eight-wheeled truck, the tracked Tunguska which also combines cannon with missiles, and the latest tracked Tor with eight vertically-fired, radar-guided missiles. For close-in defence they have Strela-10 tracked vehicles with heat-seeking missiles, plus smaller Igla-S shoulder-fired heat-seeking missiles carried by soldiers.

These systems are supposed to form a dense, layered tactical shield capable of defeating jets, helicopters, cruise missiles and drones. But Makarenko’s searching analysis show that when it comes to drones, none of them is up to the job.

“Despite the undoubted successes of the domestic military-industrial complex in the field of creating anti-UAV air defense systems, the high performance characteristics of the air defense systems indicated by the developers are not fully confirmed in practice,” Makarenko writes. The polite phrasing of “not fully confirmed” turns out to be masterly understatement; he repeatedly describes how it is “practically impossible” to hit small drones with these weapons.

You Can’t Hit What You Can’t See

A basic problem is that Russian tactical radars are not designed to pick up jets, not small, slow-moving targets.

“The results of field tests showed that the target detection radar of the Tor air defense system provides detection of small UAVs at ranges of only 3-4 km,” writes Makarenko.

This explains why drones are able to get so close and take video of these systems: the Russians are unable to spot a drone unless it is practically on top of them. When the drones are spotted, Makarenko says Tor has trouble shooting them down.

“The practical experience of experimental firing at small targets [with Tor] … indicates the low efficiency of their destruction. The main reasons for this are the imperfection of the SAM warhead detonation control system, as well as large errors in target tracking and SAM guidance on small-sized UAVs.“

This has been borne out in Ukraine, for example by this video of a Tor missile hurtling past a Ukrainian quadcopter without exploding. This is exactly what Makarenko means by a failure of detonation control.

The Pantsir has a similar problem.

“The results of field tests of the Pantsir-S1 air defense missile systems show that firing missile weapons at small-sized UAVs is practically impossible.” (My emphasis) Makaranko says that the detection range is close to the minimum range for the missiles: by the time Pantsir detects a drone, it is already too close to hir.

Exactly the same applies to the Tunguska.

“The results of assessing the possibility of firing the Tunguska anti-aircraft missile system at a mini-UAV show that firing missiles at this type of target is practically impossible,” (my emphasis) says Makarenko.

You’re Gonna Need More Ammo

Both Pantsir and Tunguska have backups though, in the form of twin rapid-fire cannon which ought to be able to annihilate small drones with ease. If only they could hit them.

“The use of cannon armament of these 3PKs against small-sized UAVs is fundamentally possible, but due to the small size of the UAVs, the probability of their defeat is low,” says Makarenko.

In a test in 2020, a battery of four Pantsirs opened fire on a slow-moving drone, but failed to destroy it with multiple salvoes.

Again, Tunguska has the same problem. It needs a ton of ammo to have any chance of hitting. And that is not an exaggeration.

“When firing at a mini-UAV of the Akila type with cannon weapons at a distance of 3 km, in order to achieve a value of the conditional probability of hitting a target equal to 0.5, it is necessary to expend from 4 to 13 thousand shells,” says Makarenko.

The Tunguska fires an impressive five thousand rounds per minute from its two cannon, but only carries 1,904 rounds in total. The above calculation suggests that a drone would have to hover within range for long enough for the defenders to empty their guns, reload, then empty them again just to have a 50% chance of a hit.

In fact, that’s not just a ton of ammo, it’s something over three tons.

This may be why we see a video apparently showing a Pantsir crew baling out of their vehicle before it gets hits by an incoming FPV drone they were unable to stop.

Missile Seeks Heat

Heat seeking missiles lije those fired by Strela do not work well either, because they are designed to home in on the hot exhaust of a jet engine. Small drones simply do not emit enough infra-red to show up against the background of the sky.

“Target acquisition via the IR channel is generally impossible due to its extremely weak thermal radiation,” (my emphasis) says Makarenko.

He notes that in the cases where it is possible – bigger drones with liquid-fueled engines which generate more heat – the missiles can usually only lock on when the drone is flying away.

He adds that most Russian surface-to-air heat-seeking missiles are fitted with impact fuses. These work well with big targets like aircraft, but unless the missile scores a direct hit on a small drone they just fly right past.

Some missile now have proximity fuses, but even then Makarenko notes that the performance is not great against small drones. To destroy an aircraft, a small number of large pieces of shrapnel is best, but these may miss a small drone altogether. What they need is a warhead which throws out a dense cloud of smaller fragments and which does not yet exist.

Bigger Problems Ahead: Drone Swarms

In a historical section Makarenko details the results of encounters between Russian air defense systems and drones in Libya, Syria and Nagorno-Karabakh, none of which worked out well for the defenders, and traces the problems back to the type of technical issue described above.

Looking ahead, he becomes even gloomier when looking at how existing systems are highly vulnerable to attacks by multiple drones coming from different directions.

“The number of simultaneously fired targets is limited to 3 for the Pantsir-S2 air defense missile system and 4 for the Tor-M2 air defense system. In this case, the targets being fired at the same time must be in the viewing area of the guidance radar. As a result, it is impossible to simultaneously work on targets attacking from different directions.” (My emphasis)

The proliferation of small, cheap drones will make the situation worse. He goes through an exercise showing which calculates that a standard air defense systems will run out of ammunition without managing to stop a swarm of 15 attacking drones.

“Light and relatively cheap UAVs can paralyze any air defense,” says Makarenko.

Ukraine aims to acquire some 200,000 drones by the end of the year.

Makarenko has many suggestions for improved defence against drones. These include new types of radar combined with optical and acoustic detection system to reliably detect drones at longer ranges. He discusses radio-frequency jamming at length, likely an important technology but one which has signally failed to stop drones in Ukraine.

He mentions other technologies familiar from counter-drone discussions in the West: new types of anti-drone shells with proximity fuzes, and microwaves and lasers. But these will all take some years to develop, and Russia is in the middle of an intense drone war right now.

Matters are not helped by a Russian media which insists that there is no problem.

“The myth that domestic air defense systems are able to cope with any challenges in the field of countering drones continues to be supported by most official experts and the media, but this is a dangerous delusion,” notes a 2022 article on Russian defense site Topwar discussing Makarenko’s report.

It would be interesting to know if Putin’s military commanders have been brave enough to mention the problem.

The problems is acute. Ukraine’s Army of Drones claimed to have destroyed 132 targets including 30 armored vehicles in one week in November. Plenty of videos suggest these numbers are fairly accurate if not understated. Many other Ukrainian drone teams operate independently of the Army of Drones.

Other nations, including the U.S. which is still working on its drone defenses, should take note. The challenge of small drones will not go away, and existing air defence provides little protection.