UK seeking Counter Small Unmanned Aircraft Systems

Essential area of defence where we cannot keep kicking the can down the road. We needs to ensure we have adequate and sufficent Anti-UAV assets, both kinetic and none kinetic, for all types and classes of possible UAVs we may come across in the future.

Let’s hope this procurement process doesn’t get screwed up by the MoD.

It would have helped if the article above had included this chart:

What we need is a big fricken laser!

Seriously though, the MoD are about 5 to 7 years behind the drag curve! The Ukrainian border conflict, was the first to use commercially bought (toy) quadcopter drones for attacking troops, after proving they were useful for surveillance. A simple servo operated mechanism that dropped a grenade into a trench was the first development, quickly followed by mortar shells carried by larger drones dropped onto vehicles.

This development was then seen in Syria and lately in Libya. Who needs a mortar when you can literally pick your target and get a 100% hit by using a drone.

Ukraine have developed a number of countermeasures. Ranging from shotguns to modified Shilka SPAAGs. They have also developed specific electronic counter measures to jam the drones control and video signals.

The problem is detection. It is very hard to visually locate a drone, let alone hear one that is more than 50m away when it’s hovering against wood or a building backdrop. Therefore you’ll need a form of active searching. You need to detect the drone at a safe enough distance, where it can’t “see” you. The heat generated by the drones motors and battery will be minuscule and only be detectable fairly close. So you need either a radar or lidar.

If we are talking about the small pocket sized class 1 drones like the Black Hornet. These are going to next to impossible to detect, unless you use a very high frequency radar operating in the V (40 to 75GHz) or W-bands (75 to 100GHz). At these frequencies the wavelength is measured in mm, so there’s a much greater chance that the beam will get a hit and return.

Following on from this would be lidar. It uses wavelengths in the nm scale. So would have a even better chance. The issue with lidar is that they generally use a mechanically steered mirror to steer the beam. These aren’t really robust enough to stand up to the abuse of field conditions. Although there have been recent developments with electronically phase steering a laser beam, which will help massively. Lidar is peculiar in that you would believe it would be massively affected by rain etc. But this isn’t the case. Because the wavelength is so small and the sweep speed so fast, it will literally map a sector which is frozen in time. Therefore the rain drops are mapped, but so is everything else around and behind it. This is constantly updated so you can use a moving target algorithm to track other moving targets like a slow moving drone that’s flying parallel to the ground and not falling.

Therefore, currently the best method to use for detecting these very small drones would be an AESA radar operating in the V or W band. The radar will be pretty small as the antenna size is about the size of a credit card or smaller. It’s range won’t be fantastic, possibly up to 5km using top end components with high power ratings, more likely 1km for “more robust” components. But the whole package, including the antenna assembly, ECU, display and battery pack could be the size of a 5.56mm ammo can, mounted on a camera tripod.

The next issue would be how to disable or kill the drone? Commercially available drones uses 2 frequencies, one for control and one for video feedback. These frequencies are governed and are centred around 2.4 and 5.8GHz. Therefore, they would be pretty easy to jam with a highly directional transmitter operating at these frequencies. Military drones are a different problem, as they may use different frequencies and randomly hop them, to counter the jamming. Which would then require a hard kill countermeasure.

You could quite easily rig up a remotely operated weapon station (RWS) to the anti-drone radar. A GPMG or 50 cal could be used, their accuracy is adequate enough to score at least one hit out of 10 rounds fired at targets around 500m away for something like a Black Hornet even further for a larger quadcopter. But you will be wasting a lot of ammo if it is moving and not hovering. Plus, there’s the issue of where these rounds will be going. A small quadcopter won’t stop the round!

I have discounted lasers, as these will need to be vehicle mounted, but also be powered by a genset for a high power output, so therefore noisy.

We have used proximity fused shells against aircraft since WW2. They work by actively transmitting either a radar signal or laser beam. If the shell detects a return signal it activates the fragmentary explosive. Where the blast wave and shell’s shrapnel damage the target, hopefully catastrophically. The problem here is that there is a minimum size for the electronics to fit into, which can be as small as a 25mm shell. But then it won’t carry enough explosive to cause enough damage. A 30mm is ok, but a 40mm is better. The larger the shell the larger the explosive content.

A 40mm auto-cannon is not a small piece of kit. We are talking something like a Bofors anti aircraft gun. The cartridges are around 400mm long. So the whole thing needs to mounted on a vehicle or trailer, not ideal for mobility or a small section. Plus the Bofors has an effective range of over 5km, a bit overkill for a target that’s only 100m away. Plus, the shell will definitely keep going if it misses the target. Though it may have a max range timer. If the Warrior program does get resurrected or AJAX’s problems are fixed, its possible that they may get an active protection system. A system like Trophy uses an X band radar, which will be ok at detecting largish drones, but not the really small ones. However, the CTA40 could be linked to the Trophy’s ECU as per the Merkava. The CTA40 has an anti-air round that could be used against small drones. Though I believe its a programmable shell not a proximity fused one?

Therefore, a weapon is needed that can be used against very close targets as well as those around 500m away. That uses proximity fusing to minimize shots fired and to have a greater chance of scoring a hit. How about the 40mm grenade fired from GMG?

These come in 3 flavours within NATO classification, a low, medium and high velocity. The version is dependent upon what they are fired from. The low velocity is fired from under-barrel launchers like the M203. The medium is a bit like an extended range version of the low velocity one and is also used in handheld weapons. the high velocity one is for use in mounted weapons like our HK L134A1 GMG. The higher velocity round helps generate the necessary force required for the weapon’s blow back recoil system. Don’t fire these from an under-barrel launcher, it will hurt!

A radar controlled RWS using a GMG mounted on a Jackal, Cayote, Foxhound etc is doable and would also have the dual role of enemy suppression. But importantly be capable of dealing with Class 1 and higher drones. The 40x53mm grenade has the available volume where a proximity fuse could be fitted, but still contain enough explosive to damage/destroy a drone.

For a foot section, it becomes a major problem. The HK weighs in close to 40kg when including a tripod. This is too much for a 8 man patrol, that will also be lugging a GPMG plus its ammo, NLAW, radios etc, doubly so if the 60mm mortar returns. The underslung grenade launcher firing the medium velocity grenades may be of use. But the team will need to be carrying and setting up the radar. Then have a means of linking the radar and operator to the grenade launcher, to make sure they point and range the target properly. I can’t really see that working to well, especially if you need to be highly mobile. Perhaps it would be better to have a two section team set up for overwatch, allowing the mobile team freedom to operate unburdened?

Out of interest just coincidentally came across this article. https://news.usni.org/2021/09/07/navy-arming-surface-ships-with-drone-repellent-system

Another interesting article
https://www.popularmechanics.com/military/weapons/a37320840/laser-guns-on-stryker-armored-vehicles/