More details of the Royal Navy’s Type 31 frigate emerge

At the start of the Type 31 frigate project, it was always acknowledged that credibility of the vessel would hinge on the weapon and sensor fit as much as the platform itself. The Arrowhead design selected by the MoD is mature but there is still another year of detailed design work and certification to complete. Although far from comprehensive, some details of the programme and the frigate’s weapon and sensor fit are now available.

The formal contract between the MoD and Babcock should be signed before the end of this year. The agreed timeframe will see steel cut in 2021, the first vessel in the water in 2023 and delivery of the five frigates between 2024 – 2028. Babcock confirmed they are going to invest £50M in a covered ship construction hall in Rosyth which will have the capacity to assemble two frigates side by side. With HMS Prince of Wales due to sail from Rosyth this week, the future for the dockyard was looking rather bleak but securing the Type 31 will provide continuity of work and more Scottish jobs for almost a decade.

Investment in new facilities also perhaps indicates Babcock has confidence it can secure export orders for construction, not just a license to design and build elsewhere. The Polish navy is known to be one of several potential customers for Arrowhead.

Babcock says they are open to sharing work around the UK in line with the National Shipbuilding Strategy. Both Ferguson (Clyde) and Harland and Wolff (Belfast) were part of the original Team 31e consortium but are in poor shape. The consortium members are not guaranteed a workshare but would be allowed to bid to build blocks. Babcock insists they won’t take risks with the programme and any commercial partners would be subject to the usual financial due diligence. Cammell Laird says they are not tied exclusively to the BAE Systems Leander bid and would be open to working on Type 31.

An Arrowhead export variant – possibly pitched as a candidate for the Polish Navy’s multi-purpose frigate requirement.

Some of the Arrowhead supply chain partners have already made early announcements about their involvement and many more will follow soon. Raytheon Anschütz will manufacture their Warship Integrated Navigation and Bridge System (WINBS) in the UK for the Type 31, a system that is already on the Type 45 destroyers and specified for the Type 26 frigate. David Brown Santaslo, who make warship gearboxes in Huddersfield, revealed they have been approached to construct the gear train for Type 31, although it will be a very cheaper and much less sophisticated than those they are building for Type 26.

When speaking to Babcock representatives at DSEI in London, they were tight-lipped about the specification for the RN’s frigates. The imagery issued to accompany their announcement of their selection as the preferred bidder on 12th September showed an Arrowhead export variant. Thales were more forthcoming about the design and presented a video simulation of Type 31 at sea (main image above) which they confirmed is a reasonably accurate representation of the RN vessel.


The broadside is back

In the era of the ‘swarm attack’ either by small boats or UAVs, light-medium calibre gunnery is back in fashion. The Type 31 will mount at least 3 modern gun systems which are well suited to dealing with multiple small targets.

The heaviest weapon will be a Bofors medium-calibre 57mm Mk 110 Mod 0 gun which is already in service with the US and several other navies. It can deliver up to 4 rounds per second and has a range of about 17km. The whole system, including 1,000 rounds weighs around 14 tonnes. This is a very different weapon to the much heavier 114mm (4.5”) Mk 8 that delivers a single shell every 2 seconds and has equipped the majority of RN frigates since the 1970s.

The Mk 110 is not optimised for supporting troops ashore but for multiple and unpredictable targets. Different ammunition types can be readily reselected, including Pre-fragmented, Programmable and Proximity-fused (3P) ammunition. It has a useful airburst mode to defend against boat swarms but could switch to defend against aircraft or missiles using proximity fuses or heavier targets using delayed action fuses. (The vast range of sophisticated modern ammunition types are a complex subject well beyond the scope of this article).

Its high rate of fire means the 57mm actually delivers a greater weight of explosive onto the target than the latest Oto Melara 76mm gun. The gun mount holds 120 rounds but can be replenished by a 3-man crew in the gun bay on the deck below.

The Type 31 will not be fitted with 20mm Phalanx CIWS but instead will mount two Bofors 40mm Mk 4 guns. These lightweight 2.3-tonne, non-deck penetrating mounts can deliver 5 rounds per second out to about 12.5km and are designed to respond rapidly at a wide range of elevations. By delivering heavier shells further away from the ship the Mk 4 is superior to Phalanx in some ways. They provide defence against air and missile attack but use the same sophisticated 3P type ammunition as the 57mm so can quickly change to engage small boat or UAV threats. 100 rounds are held in the gun ready to fire with the ability to shift between different types of ammunition.

Bofors is owned by BAE Systems so the Type 31 decision is not all bad news for the company, with an order for at least 15 gun systems and ammunition coming for manufacture in Scandinavia and the US.

  • The 57mm Mk110 opens fire. The on-mount muzzle velocity radar tracks the shells as they are fired, making small corrections to maintain accuracy (Photo: US Navy)

  • Bofors 57mm Mk110 Gun (Image: BAE Systems)

  • The 57 mm is a highly reliable weapon. The turret is seen here open for occasional maintenance (Photo: US Navy)

  • Should the RN decide to purchase a stock, the 57mm gun can also fire Ordnance for Rapid Kill of Attack Craft (ORKA) Mk295 Mod 1 rounds. This is intended as a highly accurate one-shot-one-kill round for air and surface threats. Featuring its own guidance and multi-mode imaging semi-active seeker, it can be targeted by laser designation or autonomously by downloading an image of the target prior to firing.

  • The modern Bofors 40mm can trace its heritage back to before WWII and older versions comprised the secondary armament for many Royal Navy vessels right up to the 1980s (Photo: BAE Systems)

  • Bofors 40mm Mk 4 Gun (Image: BAE Systems)

  • The business end of the 40mm gun mount – on display at DSEI 2019.

  • The NS110 radar aerial – the most capable of the NS100 family of made by Thales. Integrated with the main radar is an IFF interrogator antenna, the low power Scout Mk3 covert surveillance radar designed to detect very small objects even in high sea states, an IR-camera and AIS (commercial ship tracking) and ADS-B (civil aircraft tracking) antennas.

Thales eyes, ears and brain

Type 31 will see the Thales TACTICOS Baseline 2 combat management installed on an RN surface combatant for the first time. This is another erosion of the BAES monopoly on CMS, although some wonder if it is wise to require sailors to train on another system. TACTICOS has different strengths to the BAES offerings and is designed to be very user-friendly. Thales says that a typical warfare specialist could cross-train on the system in the space of about 5 weeks, although the configurations will differ considerably depending on the platform. TACTICOS is scalable and its open architecture and modularity mean additional mission profiles can be added easily. Apart from Sea Ceptor, Thales already has experience integrating TACTICOS with most of the weapons, sensors, decoys and communication equipment that are likely to be selected for Type 31 which should reduce costs and time.

The medium-range radar carried by Type 31 will be either the Thales NS110 (or possibly the newer, longer range NS200 incorporating GaN technology). This is a 3D AESA multi-mission S Band radar that will provide fire-control for Sea Ceptor as well as general surveillance. With a range of up to 110nm up to 70° elevation, it has dual-axis multi-beam processing which allows it to track multiple targets in cluttered littoral environments. The Radar is modular and can be tailored to customer requirements. The Artisan that equips the Type 23/26 has a similar range and works in the E/F Band but is mechanically scanned, unlike the electronically-steerable beam of the Thales AESA radar. On paper at least, the Type 31 will have a main radar that is superior to the Artisan on the Type 26, although when together in a task group it can be helpful to have different sensor types that may mitigate each other’s weaknesses. The imagery does not show the RN Type 31 fitted with any fire-control radars, so it is possible the NS110 will also provide guidance for the gun systems.

Arrowhead hits the target

Both the Navy and contractor are clear that the £250M price fully covers the production cost and will deliver a complete warship. There are other costs in building new warships and early expectations were that Type 31 would be heavily reliant on government-furnished equipment (GFE) to keep within budget. It is surprising how little of the primary systems are likely to be migrated from the Type 23 frigates but this is certainly desirable as it will reduce the need to decommission ships earlier so their equipment can be removed. It also reduces the potentially complex integration challenges of moving equipment between very different platforms.

Every item in service requires its own training and support pipeline so commonality is usually considered a priority. The RN will now have to support 3 new gun systems in service, each with its own ammunition. The Type 26 is being fitted with the very capable, but very expensive 127mm Mk 45 Mod 4 and the Type 31 will introduce two new gun calibres to the fleet.

Assessing this frigate design overall, it seems to be well-armed for its intended role in low-medium intensity conflict. For maritime security operations, it is especially well equipped while being capable of stepping up to defend itself and other vessels from air and missile attack. The 57mm and 40mm guns do have something of an overlapping capability but a heavier main gun would probably have been unaffordable. This ship will be able to throw up a wall of lethal shrapnel around itself quicker than you can say “Iranian gunboat”.

Type 31 could also make credible second-tier escorts for the carrier strike group. Anti-submarine capability is pretty limited, probably on a par with a Type 45 destroyer, although this could perhaps be partially mitigated in future with off-board unmanned ASW systems carried in the boat bays. A big advantage of Arrowhead is the generous margin of space and weight to add additional weapons and sensors including interim or future anti-ship/land-attack missiles.

13 Type 26 frigates might be preferable but are not affordable. The Type 31 should deliver 5 frigates for little more than the cost of a single Type 26 while diversifying the industrial base. There is still much more detail to emerge but it is safe to say, although Arrowhead is far from perfect, the RN can be satisfied it is getting a credible platform, allaying early the fears that Type 31 would deliver a warmed-over corvette.

Arrowhead 140 model showing approximate RN configuration. (Left) showing the guns in the A and B positions with decoy launchers on either side. (Right) Note the empty positions on each side above the hangar that could potentially also mount 2 x 30mm (ASCG) cannons. Line handling cut-outs in the flight deck corners are also a feature of the Type 26 frigate and OPV Batch IIs.

Future conundrums

Disputes between Portsmouth and Plymouth politicians about where the ships will be based are likely to become more vocal. Devonport has already been named as the base for the 8 Type 26 frigates and it has a case for deserving the Type 31s, having lost its submarines and HMS Ocean. The 5 older ‘general purpose’ Type 23 frigates will see out the twilight of their careers based in Portsmouth and there is an argument that basing the Type 31s there would be a like-for-like replacement. Portsmouth benefits from being home to two large aircraft carriers, has the six Type 45s and the surviving Hunt class MCVMs, perhaps there is sense in making Devonport the navy’s sole frigate base. As the RN is increasing the number of forward-deployed vessels, the time spent in homeport will decline, slightly reducing the significance of where they are based anyway. The Type 31s can probably expect to endure more time permanently based overseas than the Type 26s which will spend a greater amount of time assigned to the carrier group.

Like the Type 26, the Arrowhead will not fit inside covered dry docks of the Devonport Frigate Refit Complex. There may be a case for Babcock enlarging this valuable facility if an agreement can be reached to use it to maintain both of the new frigate types. As ‘their’ product, BAE Systems would be in a strong position to win the maintenance work for the Type 26 frigate but would probably prefer to do it at their existing facilities in Portsmouth.

We can also look forward to a lively discussion about names for the five ships. In recent times the Navy board (with Approval from the Secretary of State) has decided on ships names far in advance of the ship being laid down. The last Type 26 frigate has already been named HMS London more than 10 years before her construction is likely to start. The name for the first of class is especially important as the lead ship’s name will eventually replace the Arrowhead / Type 31 nomenclature in popular use.