The Type 26 frigate mission bay. Part 1 – design and development
The Type 26 frigates being built for the RN have been designed from the outset with a mission bay. In the first part of a 2-part article, we examine the design, layout and implications of this flexible space.
The mission bay concept is not a new innovation and several navies have fielded warships with a ‘flexible mission space’ for some years. The growth in unmanned naval warfare technologies and off-board systems offer a whole new way to equip warships and every self-respecting surface combatant design of today includes space for them. The Type 31e frigate design competition is currently underway and the winning candidate is likely to include a mission bay of some kind. A mission bay is not a ‘core’ requirement of the official specification, although a bay and/or deck space for modular payloads (2 x ISO containers) is a preferred option. Of the 3 outline designs in the public domain right now, the BAE Systems ‘Leander’ appears to be most developed in this regard. The Type 31e will probably be the first mission bay-equipped warship in service with the RN and will offer a way to trial different payloads and operating doctrine, in advance of the of the more spacious and well-equipped Type 26.
The mission bay, sometimes termed the Flexible Mission Space (FMS) 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, although there is also access from the forward end of the helicopter hangar. The possible combinations of items that might be placed in the mission bay are endless but the RN has said it expects space may be used for:
- UAVs, UUVs and USVs
- Maritime interdiction boats
- Humanitarian aid and disaster relief (HADR) Stores
- An enhanced medical facility
- Additional accommodation
- A holding area for captured personnel (CPERS)
The Type 26 is primarily an anti-submarine platform designed to escort aircraft carriers but has very significant capability in other roles. The mission bay is a key part of this flexibility and allows the ship to be rapidly reconfigured for alternative missions. What is perhaps most overlooked is the ability to act as an amphibious platform for raiding or special forces operations. (Interesting in light of the recent announcement of plans to add further to this capability with dedicated Littoral Strike Ships) The mission bay can hold four 12m boats for troop insertion. A Chinook can be landed on the ship (although not housed in the hangar) and the flight deck has sufficient space for its ramp to be lowered to embark 30-40 fully equipped troops. The ship has extra accommodation for an embarked military force of up to 50 personnel, although this could probably be increased further for short periods.
The Type 26 is fairly unique among escort warship designs in having a very wide transom that does not taper at all. This allows space for line-handling in cutouts in the flight deck and plenty of space on the deck below for the towed array sonar equipment. The requirement for a Chinook-capable flight deck (c30m x 20m) is a big factor in driving the up the displacement of the ‘frigate’ to about 8,000 tonnes but makes for much more comfortable helicopter operations. The hangar is capable of housing a Merlin or two Wildcat helicopters. Theoretically, a second Merlin could be accommodated by bringing one forward into the mission bay. With one kept on the flight deck or airborne, this might offer a sustained, round the clock ASW capability in the absence of an aircraft carrier. A shutter can close off the hangar from the mission bay, primarily to prevent the spread of fire. As the hangar is often used for social or diplomatic functions it may also be useful to hide the contents of the mission bay from public view at times.
Mission bay enablers
Although a flexible mission space is a simple concept, there are a surprising number of additional elements needed to make it safe and efficient to be used operationally at sea. Like most compartments in a warship, the bay will need basic lighting, ventilation and fire-fighting arrangements. With such diverse potential items stored in the space, there will need to be flexible means for securing them. ISO containers require correctly spaced deck sockets and are secured using twist locks. Containerised modules may hold sensitive electronics and, for use in a naval environment, will need shock-protection mounting. Accommodation or mission modules intended to be used by personnel when on the ship will rely on the ship’s services to supply power, heating, ventilation and air conditioning (HVAC). With a wide variety of boats and bulky unmanned systems to embark each may require a bespoke cradle to secure them tightly to the deck when at sea.
Without a means to move items in and out of the mission bay, it is merely an empty space in the ship of limited value. The Mission Bay Handling System (MBHS) is a critical and complex mechanical system 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 MHBS must also have sufficient reach to cover all areas of the mission bay and have attachments capable of lifting items with a variety of weights and dimensions. To allow the ship to use austere port facilities, the specification also calls for a self-loading/unloading capability. The MBHS has to have the strength and reach to load or offload containerised mission packages from the jetty without the aid of dockside cranes. It would appear that items for the mission bay are intended to be loaded via the doors on each side of the ship and not usually through the hangar. Mock ups suggest the MBHS would have a limited reach within the hangar area.
Rolls-Royce Canada based in Peterborough, Ontario has considerable experience manufacturing marine container and load-handling equipment for the commercial sector and signed a Design and Development Agreement for the Type 26 with the MoD in 2014. The contract for the manufacture of the MBHS for the first three ships in was awarded in February 2018 and RR Canada is also manufacturing the low-noise propellors for the Type 26. The inclusion of Canadian industry in the project at an early stage was a sensible strategy that undoubtedly contributed to the selection of the Type 26 design for the 15-ship Canadian Surface Combatant. With an international programme to build up to 35 frigates that are all likely to use the MBHS, this is an example of how economies of scale may reduce costs for all three participating nations.
The MBHS 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 will require attachment heads designed for the different type of loads. Besides the 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. Different lifting attachments may be developed in future to suit the weight and shape of evolving unmanned systems. Although 20-foot ISO containers can theoretically hold up to 22 tonnes, the mission modules will be limited to the MBHS capacity of 15 tonnes.
The boat bay
The Type 26 design includes a separate boat bay on the port side. This gives the ship has at least one general purpose sea boat, in addition to whatever other boats may or may not be carried in the mission bay. The RN is currently receiving deliveries of 60 new BAE Systems Pacific 24 Mark 4 RIBs. These boats are a major improvement on the Pacific 24s currently in service, being SOLAS certified, having a 370Hp V8 engine giving speeds up to 38 knots and fitted with SHOXS shock-mitigation seats. RN vessels are not be certified as safe to deploy until they can demonstrate their sea boat can quickly recover personnel lost overboard. The sea boat also performs important operational roles – for boarding other vessels and transport of personnel. The Pacific 24 is set to remain as the standard RIB employed by the RN for some time and will see service on the T26. The Type 26 boat bay is likely to be a similar design to that of the Type 45 destroyers.
The size of Type 26 offers the potential for its use as the basis of the design for future combatants. An air defence or anti-ballistic missile variant could perhaps replace the mission bay with additional vertical launch cells. The design features some spare electrical generation capacity but should it be insufficient for the needs of future directed energy weapons (DEW), then it is possible that extra power generation modules could be installed in the mission bay. There are very few disadvantages to having a large spare space in the superstructure of a warship and the mission bay is likely to prove very useful in service and embark equipment that has not even been imagined yet. In the next article, we will examine some of the potential configurations and types of payloads that might be carried.