After two years of war in Ukraine, the facts have spoken: UAS, or drones, evolve at rapid pace, as do counter-UAS systems. But at the heart of this race to be the biggest innovator lie some key problems – what does it really take to counter drones, and what are the real costs for navies?

Since the beginning of the conflict it has become evident that UAS are no longer just a problem for land forces to contend with. The use of such systems (both aerial and surface) by the Ukrainians to attack Russian bases twice in 2022 clearly shows that drone warfare has entered the naval domain... Continues below

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Above: Traditional CIWS such as the ubiquitous Phalanx fire expensive ammunition, and might well run out of it before defeating a mass drone swarm. (Photo: USN)

And while the reported use of Australian-made cardboard drones (Sypaq’s Corvo) to destroy bomber aircraft on a Russian base last August is not a naval matter, it does speak to another important evolution in drone warfare. Namely, it is now possible to attack critical capabilities costing millions of dollars with a mass of expendable assets costing only a few thousand.

The maths are, to say the least, painful.

Within the naval domain, one can argue that various systems on a ship may be used for C-UAS purposes, such as close-in weapon systems (CIWS), jamming or, more recently, bespoke drone guns. Yet each one of these options also represents an arithmetic conundrum.

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The main advantage of drone warfare is that it allows an adversary to use multiple, relatively cheap (compared to, say, missiles, ships or fighter jets) and expendable capabilities simultaneously to overwhelm a vessel’s defences. Such tactics exploit the fact that most self-protection layers on board today’s ships – from detection, identification and tracking to engagement – have not been designed to tackle such a threat.

‘Drones move very quickly, some well above 100km/h, can be very small and are likely to come at a ship from different angles and directions,’ Red McClintock, director at DroneShield, told the author, ‘so while it is possible to hit one with a CIWS, it is likely to take multiple rounds before being successful'.

A CIWS round can cost anywhere between $15 and $30, so assuming that it takes a thousand to hit one UAS, if there are 30 of them attacking a ship it may need 30,000 rounds to neutralise them all. That’s up to $900,000 to defeat a small swarm.

More important is the size of the CIWS magazine. A Phalanx Block 1A, for instance, is reported to hold only 1,550 rounds in the drum. If swarming tactics involve repeatedly attacking a ship until it runs out of ammunition, it is not a stretch to imagine the outcome of such situation. 'For that reason, you would not want to rely solely on CIWS in a swarm attack except to destroy the very last ones – the leakers.' McClintock commented.

The other option to protect a ship from a swarm of drones would to use jamming systems. These can be very effective against UAS that do not have built-in inertial navigation and/or anti-jamming capability.

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While this solution would assuredly be far less eye-wateringly expensive, there is another issue to contend with: while both radar and jammers are focused on tackling drones, they are not available to detect and defeat anything else – say an anti-ship missile. In fact, among the multiple theories that emerged to explain the sinking of the Moskva, this scenario was mooted.

Finally, over the past year some navies (the US and French, for example) have been experimenting with the use of handheld drone guns on board their ships. Several other fleets are reportedly looking into those technologies too.

Evidently, the main advantage of such systems is their targeted effectiveness that, much like deploying jammers, would prevent any friendly fire accidents – a potential concern when using CIWS. The drawback, however, is precisely the fact that they are very focused, and therefore unable to offer a protective sphere to a ship under swarm attack.

Above: C-UAS jammers have been trialled by the USN, among others, but these will need to be replaced or upgraded regularly to remain effective as drone technology evolves. (Photo: USN)

Ultimately, several industry sources have indicated that there is no perfect solution or combination for the most effective and efficient onboard C-UAS.

The reality on the ground (or rather deck) is that both drones and C-UAS solutions evolve very quickly and navies are stuck between a rock and a hard place as they attempt to find the right compromises within the appropriate cost margins.

The attack on the Russian bomber base, for instance, revealed that with a relatively simple UAV equipped with all the right technologies, it is possible to inflict significant damage. If cardboard drones can do that, how can radars, for instance, evolve to be able to detect their very limited radar cross-section? ‘The physics of the situation will be challenging for any CIWS in many nations,’ McClintock said.

Navies will try to stay ahead of the UAS threat, but finding the appropriate defence is a moving target that will continuously involve complex maths problems.

If even a 5% success rate for a drone sortie can inflict significant damage, then wouldn’t it be worth acquiring the most advanced C-UAS? Yet those systems can become very expensive and may quickly become outdated, given the pace of technological evolution.

So, is it better to buy larger quantities of cheaper systems regularly to address a current threat, or a lesser quantity of more expensive ones that will effectively protect but potentially only for a short while?

And what about the time and money needed to train crew to handle those systems and be proficient in countering UAS? ‘Whether technology is outdated in a couple of months or a couple of years, crew still need to learn how to use them and how adversary tactics are likely to evolve to defeat them,’ McClintock concluded.

Critical maths versus critical mass… Who will win?

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