To some extent, the capability of the Royal Navy’s Type 31 frigate cannot be fully appreciated without understanding the background to its development. Public perception has perhaps been over-focused on cost and initial armament, obscuring what has been achieved. In this article, we look at the procurement process and design philosophy that underpins the project.
Compared to previous procurement programmes to deliver complex warships to the RN, Type 31 differs greatly and has been relatively rapid. In the past, bespoke from-scratch designs were generated over long periods of time and subjected to detailed cost versus capability trade-offs. Sometimes there has been reliance on a monopoly supplier with no or limited competitive processes. Major changes to the design were often made at various points in the programme, including after construction commenced, significantly adding to cost and technical risks.
For Type 31, Navy Command, DE&S and other stakeholders drew up a list of requirements, known as Key Characteristics (KCs) for a basic general purpose frigate (GPFF). These KCs were graded in accordance with safety criticality and priority. Certain KCs were assigned as ‘Key Hazard Certification’ and had to be achieved as a minimum, in areas such as stability, structural strength, fire-fighting and magazine safety. Other mandatory characteristics included meeting shock resilience parameters, weapon storage criteria and ship operation within a defined seawater temperature range. The remaining KCs were rated on a 3-level priority scale and evaluation tools were used to score the designs against them. Other aspects such as UK prosperity, export strategy and project management were also factored into the assessment.
The short competition period and defined budget effectively necessitated the three companies bidding having to base their solutions on existing vessels. All design decisions are made by the Prime contractor (or the mission system integrator) acting as the Design Authority instead of DE&S and RN personnel. After the bids were thoroughly evaluated against the KCs, the winner was awarded a fixed-price contract and the MoD has very limited options to modify the design during the build phase.
In late 2018 the Competitive Design Phase (CDP) began, culminating in September 2019 when Babcock was selected as the prime contractor and Thales UK sub-contracted as the mission system integrator. Despite COVID, the project is currently on track with HMS Venturer due to be launched in 2023 and handed over to the RN in 2025. The MoD are currently working on the pre-In Service Date sequence of activities such as hot weather trials and weapon certifications. Post-delivery Capability Insertion Periods (CIP) that are not the responsibility of the contractor, will allow the addition of new equipment and software to avoid obsolescence and offer the option for more major upgrades early in the ship’s careers. There is still a long way to go and plenty of milestones that need to be met very precisely in order for Initial Operating Capability to be achieved in 2027, just 6 years after the first steel was cut.Type-31-platform-design-1
The Danish Navy’s Iver Huitfeldt (IH) class frigates are the parent design for the Arrowhead-140 product from which Type 31 is derived. Scantling plans (framing and dimensions) and Piping & Instrumentation Diagrams (P&IDs), compartment arrangements and the original 3D CAD model were all used as the starting point. The IH were based on the Absalon class, a design that dates from the late 1990s, conforming to Det Norske Veritas (DNV) ship rules. Type 31 is designed to modern and more stringent Lloyd’s Register Naval Ship Rules, NATO ANEP-77 Naval Ship Code and the UK DEFSTAN 02-900 General Naval Standard.
The improvements include increased compartmentalisation and watertight subdivision which are a vital aid to stability and recoverability in the event of sustaining damage. Greater redundancy – ie duplication of systems to provide backup and reversionary modes. Blast protection in the form of composite armour to protect vital areas of the ship. Enhanced shock resilience to ensure critical systems remains working in the event of the ship being hit. Signature mitigation measures to reduce the radar returns, noise and heat emitted from the ship, taking into account external changes from IH to T31. Compliance with IMO Tier III environmental regulations using Selective Catalytic Reduction to reduce nitrogen oxide (NOx) exhaust emissions.
Constructing and maintaining ships to these codes is the result of the RN’s hard-won combat experience and are some of the most exacting standards used by any navies worldwide. Although not immediately obvious, in regards to safety and survivability, the Type 31 platform will be superior to many overseas competitors and the RN’s legacy Type 23.
Only proven and off-the-shelf systems have been selected for inclusion in Type 31 which is another major reason that the project can be progressed faster with lower risk and cost. The TACTICOS Combat Management System is already in service onboard more than 180 other naval vessels and Thales has considerable experience in customising and integration. The Integrated Platform Management System (IPMS) and Damage Surveillance and Control (DSAC) equipment are common to the QEC aircraft carriers and Type 26 frigates. The Integrated Bridge & Navigation System (IBNS) is the same as fitted to the Type 45 Destroyers and Type 26. The communications equipment is also a modified and updated version of that used by the carriers. Throughout the ship, from the ballast water treatment plant to the propulsion gearboxes to the galley equipment, Military Off The Shelf (MOTS) or Commercial Off The Shelf (COTS) equipment has been utilised.
Adaptability and export
Arrowhead-140 and T31 were designed to be highly adaptable from the start. The baseline platform has the key features discussed above and is spacious, has good habitability and endurance with scope for upgrades. There is redundant processing capacity within the IPMS system, additional electrical generation and distribution capacity and margins in chilled water, HVAC and network infrastructure.
Cynics will argue that this is just another example of ‘fitted for but not with’ (FFBNW) and the RN has a track record of ships fitted for, but never with some equipment. Historical precedent aside, building an adaptable platform requires more than just leaving empty spaces and T31 has the infrastructure in place to make it cheaper and quicker to add major new capability. When the first Type 23 frigates went to sea in the early 1990s they lacked even a functioning Combat Management System but over time they have been upgraded and improved and are still effective 30 years later.
Type 31 will be built with the foundation structural seats for four 8-Cell Mk41 Strike-Length VLS modules. In light of justifiable accusations the surface fleet “acts like porcupines – well-defended herbivores with limited offensive capabilities”, the RN is known to be actively considering the addition of these 32 cells. Equipped with the FCASW/FOSW anti-ship/land attack missile, the T31 would gain a very significant increase in reach and firepower.
Like the Type 26, Type 31 has been entirely designed in 3D modelling software, down to the level of individual domestic plug sockets within compartments. Outputs from the 3D model directly drive the new PEMA pulse line (automated steel cutting and welding) manufacturing facilities in Rosyth. 3D modelling considerably reduced the risks during construction as equipment, pipe and cable runs have been routed and deconflicted in a virtual model before any building takes place.
The 3D model also makes it simpler to adapt the design for export or upgrade and already contains additional equipment that might be added. Original manufacturers have provided details to construct CAD models for items including the BAES 127mm Mk 45 Mod 4 Medium Calibre Gun and the Thales CAPTAS towed array sonar series.Type-31-Gunnery-control
The gun armament is a good example of the new procurement approach. The high-level KCs laid down by the MoD specified gun armament to engage surface and air targets. The bidders were left to choose the weapons and sensors and their proposals were evaluated by DTSL using tools including the Ship Air Defence Model (SADM) amongst others. SADM was developed by BAES in Australia and is used by several navies for virtual simulation of weapons, sensors and electronics in complex above-water combat scenarios for testing purposes.
The critically important selection of the gun systems for Type 31 took over a year, and all options available on the market were considered. Babcock Team 31 conducted their own evaluation of each examining servo behaviour, reaction times, fragmentation patterns and accuracy. Other aspects such as the weapon arcs, mission systems integration, deck-penetrating magazine support and reversionary control were also carefully considered. The BAES/Bofors 57mm and 40mm guns finally chosen are not the cheapest solutions available but provide the best combined performance in relation to the KCs.
The other key components of the T31 combat system are the primary radar and CMS. The latest variant of TACTICOS selected for T31 will introduce automation of processes such as picture compilation and rapid assignment of fully integrated weapons to the RN. (The CMS fitted to T26 will have similar capabilities). The NS110 radar will be the first 4D dual-axis, multi-beam, Active Electronically Scanned Array (AESA) radar to be fitted to an RN frigate. 4D radars not only provide bearing, range and elevation (3D) information but also provide in-depth analysis of the target’s doppler (velocity and manoeuvring) and ten times more time on target (the 4th dimension) by applying dual-axis multi-beam processing. The result is superior air and surface detection, tracking and classification performance.Royal-Navy-Type-31-frigate-General-Arrangement-8
This piece is focused on the acquisition and design phase but Babcock must now meet the different challenges of fabrication, fitting out and test & commissioning. As experience with the Astute programme clearly demonstrates, having a mature design in place before commencing construction is key to success and in this regard, Babcock are on a sound footing. It should be noted that a relatively small team of around 100 designers working on Type 31 have achieved a great deal in a short time.
The suggestion by Sir John Parker in the original National Shipbuilding Strategy that GPFF/T31 should be sold after around a decade in service and replaced with new build ships to keep production lines busy is admirable but has not been adopted or officially endorsed as the plan for the ‘Inspiration class’. It is much more likely T31s will have long careers in the RN and be extensively upgraded over time, a future for which they are well placed.
This article is based on a paper submitted to the International Naval Engineering Conference, November 2022 by James Johnson (Type 31 Frigate Transversals Engineering Manager) and Matt Howard (Chief Engineer, Arrowhead-140), Babcock International, Bristol.