Refining the requirements for the Type 26 frigate mission bay

In a previous article, we took a speculative look at how the Type 26 frigate mission bay could be utilised. More than four years on, the RN has provided some further detail on the specifications for this space on its future surface combatant.

With all Type 26 frigates on order and the construction of the first 3 vessels well underway, some development work has been done on the requirements and capability of the mission bay, sometimes termed the Flexible Mission Space (FMS) that occupies, the central part of the superstructure. Although a FMS appears to be a simple idea, there are a surprising number of additional elements needed to make it a safe, efficient and operationally useful space.

In parallel, the RN has been developing its PODS concept to provide containerised capabilities for Type 26 and other platforms. At this early stage, the RN has conducted trials with PODS containing a quantum navigation system, new radars and software under test and a prototype modular medical capability pod. In the long term, the RN plans to have a suite of PODS which has the potential to give the frigates a much more comprehensive range of options. With the right mix of equipment carried in the FMS, Type 26 could have its own organic mine warfare capability. The space could also be used to embark special forces and their boats for littoral strike operations. For humanitarian aid and disaster relief, food, medical supplies and water-making modules would give the ship far greater capacity to offer support than can be carried by legacy frigates.

Perhaps the most intriguing of all the FMS possibilities are the ways to enhance Type 26’s core ASW capability. The most obvious being the embarkation of UUVs and XLUUV is to extend the range and reach of the ship, taking a sensor into the depths which are the natural environment of the adversary. BAE System’s containerised ASW Torpedo Launch System concept would appear to offer a way to mitigate the lack of a fixed TLS on Type 26. It might also be adapted to launch mini torpedos for countering UUVs. The large rotary wing UAV under development in the PROTEUS programme that will complement and possibly eventually replace the Merlin helicopter, may also ultimately be embarked in Type 26. The FMS can be used as additional hangar space for both large and small UAS.

Consideration has also been given to the ashore support infrastructure. The Type 26 frigates will be based in Devonport and a Mission Module Mounting Area is being established at South Yard which should be ready to support HMS Glasgow’s phase 2 sea trials sometime in 2028.

The mission bay occupies the full width of the ship and is about 20m wide by 15m long. Access is through two large roll-up shuttered doors on either side of the vessel together with convenient fore and aft access through the forward end of the helicopter hangar. There is space for up to 10 TEU (20 foot) containers or 5 FEU (40 foot – loaded through the hangar). There are also sufficient securing points on the deck to accommodate sub-TEU size containers, mainly favoured by military users, the Bicon (10 foot), Tricon (6.5 foot) and Quadcon (5 foot). The mission bay is designed for a total of 150 tonnes of containers or equipment. The maximum allowable weight of a single FEU is 18 tonnes. (The RN’s CETUS XUUV is designed to fit inside an FEU container and weighs 17 tonnes).

Containers are secured to the deck inside the FMS using standard twist-lock connections but of military grade, shock qualified for 15-tonne loads. Studies into the effects of underwater shock, blast, and fragmentation on mission modules recommend that TEUs meet the DNV 2.7-2 enhanced container manufacture standard. This was originally developed by Det Norske Veritas (DNV) for the offshore industry that needed more rugged containers.

Most containers carried in the FMS will not just be dumb boxes used for storage but will need to plug into a range of services supplied by the ship. The space must therefore have a substantial infrastructure of pipework and accessible connection points. Services include low and high-pressure (8 & 300-bar) air for pneumatic systems, chilled water for cooling electronics, electrical supplies (440/230 and 115v), a diesel supply and drain facility and fire and smoke detection/suppression systems. To support the accommodation of personnel in TEU modules there will also be heating and ventilation connections, fresh water supplies and black and grey water (sewage) handling.

Of great importance will be the secure data connections and architecture that will allow autonomous systems or weapons to be recognised and instantly integrate with the ship’s main Combat Management System (CMS). Work to standardise these physical connections and data protocols for Navy PODS, and more widely across all NATO containerised capabilities, is ongoing.

Data will need to be exchanged in both directions between the ship and systems in the FMS. For example, the Portable Operations Centre (POC) in the mission bay used to run a mine warfare operation may need to share the ship’s radar picture and radio communication facilities, while the PWO in the ops room needs to be able to monitor the mine hunting plot.

Without a means to move items in and out of the FMS, it is of limited value. The solution is a bespoke Mission Bay Handling System (MBHS) – a critical and complex mechanical assembly that must meet some demanding specifications. The primary requirement is to safely deploy and recover boats and unmanned vehicles from both sides of the ship when at sea while subject to rolling and pitching motions. The MBHS must also be capable of loading, unloading and stowage of cargo while in harbour, assist maintenance activities and movement of cargo within the FMS. The system also has to meet British Naval Shock Standards, Lloyds Naval Ship Rules 2020 and Lifting Appliances Marine Environment (LAME 2021) regulations.

The contract for the manufacture of the MBHS for the first three ships in was awarded to Rolls Royce in February 2018. Their sophisticated solution is based on a commercial rail-mounted Launch and Recovery System (LARS) and uses a mix of hydraulic and electro-mechanical actuators to slew, lift and telescope. It can transverse the width of the bay on athwart-ships rails mounted on the deck-head. When launching or recovering boats, a constant tension winch is controlled using an Active Heave Compensation (AHC) system. AHC can precisely sense vessel motion and automatically compensate by adjusting the winch speed and direction. The MBHS is designed to move its maximum payloads in harbour or sheltered waters up to sea state 2. Crewed and uncrewed systems weighing up to 10 tonnes can be launched and recovered over the side in moderate conditions, up to sea state 6 (swells to about 2 metres).

The MBHS has a docking head designed to accept a variety of attachments for handling different loads. Besides a winch and grab mechanism used for lifting boats, a beam spreader for lifting containers will be required as well as a crane and hook for moving smaller loads using lifting slings. Different attachments may be developed in future to suit the weight and shape of evolving uncrewed systems. By transversing the rail system, the MBHS can reach up to 16 meters from the centreline (the ship’s beam is 20.8m) allowing a reach of over 5 meters over either side of the ship. The total payload that can be lifted is 16.5 tonnes (including the 1.5-tonne weight of the lifting attachment). An empty TEU container typically weighs between 2.4 – 4 tonnes, depending on the manufacturing standard and can theoretically hold up to 22 tonnes of cargo. The safe working load for a TEU loaded into the Type 26 mission bay using the MBHS, therefore, implies a maximum internal payload of around 11-12 tonnes.

To some extent, the RN will only discover the full potential and practical limits of how the FMS can be used through extensive trials and experimentation at sea with the early Type 26 frigates. The RN’s PODS concept announced in 2021 was greeted with indifference in some quarters but will make increasing sense as the Type 26 and Type 31/32 frigates enter service. Modularity is not a panacea but is being adopted by many navies looking for the ability to rapidly add capabilities to make use of new technologies to match evolving threats. The FMS will undoubtedly be used in future with many different configurations and equipment not even thought of yet. The journey has only just begun to fully exploit this new capability.