Propulsion specialists eye AWD, LHD opportunities

Key equipment suppliers are trying to shape the Navy's AWD and LHD programs, and position themselves to win key supply contracts on these projects.
If the Government decides Navy should have an Air Warfare Destroyer designed by Gibbs & Cox and based on the US Navy's DDG-51 design, what sort of power plant should it have?

Similarly, what are the power generation and propulsion options for the Navy's LHDs? Both contenders - the Navantia SPS and Armaris Mistral class LHD - employ electrical propulsion and steerable propulsor pods.

These are not simple menu items which the DMO can tick in passing: these are significant configuration items which will impact on the reliability, availability and cost of ownership of both ship classes throughout their service lives.

In Renk's view a CODAG configuration is the most flexible and cost-effective - this configuration enables a single diesel to drive twin propeller shafts. The company is the only one so far to have built CODAG gearboxes and set them to work: its CODAG gearbox on the German Navy's F124 destroyer has achieved 5,000 trouble-free hours so far and Renk is supplying a similar gearbox to the US Coast Guard for a new ocean-going cutter design. It features low vibration and noise through the use of double-helical gearing.

Rolls-Royce believes CODAG is a viable option - but also believes electrical propulsion is a realistic option for the AWD, given the length of time it will be in service and the presently unquantifiable power requirements of future sensors and weapons.

Rolls-Royce has staked a claim on the AWD and LHD programs based on its range of marine diesels and gas turbines, and also the unrivalled range of propellers, propulsors, stabilisers and water jets it can offer following its acquisition of a range of marine equipment suppliers in Scandinavia, Europe and North America over the past decade.

The company has a significant local presence. For example, the RAN's FFG and Anzac frigates use Rolls-Royce's Bird Johnson propellers and Brown Brothers stabilisers, while the LPAs Manoora and Kanimbla use Bird Johnson propellers and shafts; the company carries out service and overhaul of Bird Johnson propellers in Australia and has sufficient installed infrastructure to expand this coverage to other Rolls-Royce family products, according to David Bricknell, the company's vice president for naval systems.

Rolls-Royce has a significant stake in the LHD program: it is currently the incumbent supplier of propulsors and stabilisers for the French Navy's Mistral-class LHDs. These ships use KaMeWa's 7MW Mermaid propulsor pods; if ordered by the RAN Rolls-Royce would look to provide the same system, and potentially also a set of Bergen medium-speed diesels. These are a modular design delivering 5kW per cylinder and could be used for both on-board power generation and propulsion.

Bricknell told ADM Rolls-Royce would like also to provide equipment for the Navantia SPS design if this is selected. But the SPS uses a different type of double-ended propulsor pod and the RAN may not want to change such a critical element of the vessel's design, so the company's opportunities may be confined to stabilisers and diesel generators.

However, Rolls-Royce already has a significant role in the US Navy's DDG-51 fleet and believes it can leverage this in the AWD project. Each of the DDG-51s is equipped with three AG9140 2.5MW gas turbine generator sets to provide a stable power supply for the Aegis air warfare system and radar. The company also provides the DDG-51's Bird Johnson controllable pitch propellers.

TheAG9140s would probably suit the evolved DDG-51 design being developed by Gibbs & Cox, but for the AWD project Rolls-Royce may also offer the RR4500 gas turbine generator sets. This has a 4.5MW output and will be paired with the MT30 gas turbine on the US Navy's new DD(X) destroyers; these ships will employ electrical propulsion with the MT30 as the propulsion generator and the RR4500 providing electrical power for the sensors and weapons.

As far as propulsion for the AWD is concerned, Bricknell believes all-electrical propulsion, as adopted on the British Type 45 destroyer and the DD(X), is not a likely prospect. These ships require about 5.5KW per tonne of displacement to reach 30kts, while the AWD is likely to need about 8KW per tonne to reach 30kts - the 'power density' issues required to get that extra 2.5KW per tonne in a vessel of that size are just too hard, he says.

However, a Combined Diesel/Electric or Gas turbine (or CODLOG) configuration would deliver the speed and fuel economy the Navy wants, Bricknell told ADM. The electric drive would propel the ship at speeds up to 15-20kts at which point the gas turbine would kick in to deliver the 30kt maximum speed. While something of a departure from the DDG-51 tradition, Bricknell points out that a part-electrical propulsion system can have sufficient power margins to handle future growth, and especially electrical weapons. The power demands of future combat systems and sensors, electrically-initiated guns and even particle beams are hard to predict, but an electrical propulsion plant provides a solid base for meeting them.

Bricknell estimates a CODLOG or even a simple CODOG configuration (Combined Diesel or Gas Turbine) would give the AWD a range of around 6,000nm at 18kts - or an 80 per cent increase in range for the same fuel oil bunker capacity as the current DDG-51.

The MOTS alternative for the AWD program, Navantia's F.100, uses two LM2500 gas turbines which won't provide the top speed the RAN requires, Bricknell said. Depending on how far the RAN might want to modify an otherwise very sound basic design, Rolls-Royce could design a new power plant for this ship if the RAN required it to.

Rolls-Royce's MT30 has been selected for the US Navy's DD(X), for the Royal Navy's CVF carrier and for Lockheed Martin's Littoral Combat Ship (LCS) design; the engine delivers 36MW at a standard US Navy 100 degree Fahrenheit day and, according to Bricknell, two MT30s deliver the same power as the existing four LM2500 gas turbines which power the DDG-51. The LCS has a CODAG (Combined Diesel and Gas Turbine) plant with an installed power output of 84MW, propelling the 3,000 tonne ships at speeds in excess of 50kt.

Supporting the MT30 engine in RAN service wouldn't require a huge investment in local infrastructure, Bricknell told ADM. The MT30 is derived from the Trent 800 aero engine, has 80 per cent commonality with it and a projected 24,000-36,000 hours Mean Time Between Overhaul (MTBO). The Trent 800/900/1000 family will be supported locally by Qantas which has ordered the engine for its Airbus A380 and Boeing 787 airliners.

German engine and vehicle manufacturer MAN B&W is also eyeing opportunities in both the AWD and LHD programs. The company will be a strong contender for the Army's Project land 121 - Overlander, and is looking to use synergies between its vehicles and marine business to strengthen its bid to provide generator and propulsion diesels for the LHDs and AWDs.

On the AWD project the company has been talking to Gibbs & Cox about the possibility of providing its 12RK280 diesel as the low-speed propulsion motor for the evolved DDG-51. It has also proposed 2MW auxiliary generating sets for the AWD based on its 12VP185 diesel engine.

Significantly, both engines have already been adopted by naval customers in the region: The Royal New Zealand Navy is the launch customer for the 12RK280, which is the main propulsion motor for the two new Offshore Patrol Vessels which Tenix Defence is building under Project Protector. And the 12-cylinder 12VP185 is the main propulsion motor for the three Inshore Patrol Vessels Tenix is building under Project Protector (the first of which will be commissioned early next year) as well as for the Rail Corp NSW XPT railway trains.

MAN is also providing four 16-cylinder 16VP280s to Incat in Hobart as main engines for two new fast ferries which are currently under construction. In fact, MAN B&W provides all of the main engines gearboxes and generator sets for the RNZN's new fleet of OPVs and IPVs, and so has strengthened its military marine support capabilities in Australia - its current fleet in the region includes main engines and generator sets aboard HMA Ships Tobruk, Success and Sirius (still currently named MV Delos) as well as the RAN's two major hydrographic ships, HMAS Leeuwin and Melville.

Interestingly, the 20 auxiliary generating sets which MAN is providing for Project Protector are supplied by the company's trucks division - they are derived from truck engines and so provide the basis for a logistics and supply chain which will support MAN's bid for Project Overlander.

The company also has its eyes on the LHD program. The company owns two thirds of the Piehlstick diesel company and will offer the Piehlstick PA6B STC engine to drive the Mistral's 7MW KaMeWa Mermaid electrical propulsor pods.

By Gregor Ferguson, Adelaide