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Royal Navy Type 45 destroyers cannot take the heat

The UK then joined France and Italy in the Horizon-class class of air-defence destroyers frigate program; however, differing national requirements, workshare arguments and delays led to the UK withdrawing on 26 April 1999 and starting its own national project Type 45 destroyer. The class is primarily designed for anti-aircraft and anti-missile warfare and is built around the PAAMS (Sea Viper) air-defence system utilizing the SAMPSON AESA and the S1850M long-range radars. The Type 45 destroyers were built to replace the Type 42 (Sheffield class) destroyers that had served during the Falklands War, with the last Type 42 being decommissioned in 2013.

The six Type 45 Daring Class destroyers, which cost the taxpayer £1bn each, are the backbone of Britain’s combat force at sea and are among the most advanced missile destroyers in the world. They are the Royal Navy’s first all-electric ships and are driven by two Rolls-Royce WR21 gas turbines and two Wartsila diesel engines. The WR21 is designed to deliver significantly improved operating costs by using an intercooler recuperator, which recovers exhaust and recycles the gas into the engine. But, as a rule, power turbines slowed down in warm temperatures.

But the engines powering the Royal Navy’s cutting-edge fleet are unable to operate continuously in the warm waters of the Gulf. Responding to questions about why the power systems failed in warmer waters than the UK, John Hudson, managing director of BAE Systems maritime, said the original specifications for the vessel had not required it to sustain extremes. “The operating profile at the time was that there would not be repeated or continuous operations in the Gulf,” he said.
Tomas Leahy, of Rolls-Royce naval programmes, said the destroyer was now operating in “far more arduous conditions than envisaged in the specifications”. “This is not the fault of the WR21,” said Mr Leahy. “It is the laws of physics.”

But the Type 45 was designed for worldwide operations from sub-Arctic to extreme tropical environments and continues to operate effectively in the Gulf and South Atlantic all year round. It also emerged that some of the difficulties were rooted in late-stage design changes demanded by the US Navy, when it was leading development of the electric propulsion system. However, the US Navy pulled out of the programme in 2000, when it was taken over by the UK’s MoD. Mr Leahy said that only 1,900 hours of testing had been carried out on the system after the design change, while the problems only emerged after 4,000-5,000 hours of operation.

“With hindsight it would have been good to do another 4,000-5,000 hours of testing on it,” he said. The MoD is having to set aside tens of millions of pounds to fix the destroyers. The plan is to install two extra diesel engines which will require cutting a hole in the hull of the brand new destroyers. The costs of repairing the Type 45 were forcing a delay in the Type 26 frigate programme. Original plans were for the first steel to be cut on the frigates by the end of this year, but this is now not likely before December 2017. The government had already weakened the Royal Navy’s capabilities by cutting the number of frigates that would be ordered from 13 to eight in last year’s strategic defence and security review.

The Type 45 uses a pioneering system called Integrated Electric Propulsion (IEP). There are many advantages associated with IEP, fuel efficiency, flexibility in locating the engines and a supposedly reduced maintenance and manning requirement. In basic terms, two WR-21 gas turbines (GTs) and two Wartsila 2MW diesel generators provide AC power for the motors that propel the ship as well as the power for the ships systems – weapons, sensors lighting etc. The WR-21 GTs were designed in an international partnership with Rolls Royce and Northrop Grumman Marine Systems. The turbines are of a sound design but have an intercooler-recuperator that recovers heat from the exhaust and recycles it into the engine, making it more fuel-efficient and reducing the ship’s thermal signature. Unfortunately the intercooler unit has a major design flaw and causes the GTs to fail occasionally. When this happens, the electrical load on the diesel generators can become too great and they ‘trip out’, leaving the ship with no source of power or propulsion.

The MoD has not revealed how frequently these blackouts have occurred but the first 2 ships, HMS Daring and HMS Dauntless seem to have suffered the most. The first indication of problems was as far back as 2010 when it was admitted HMS Daring lost all power in mid-Atlantic and had to be repaired in Canada. Although the Type 45s have been active, some significant commitments have been missed. An indication that all is not well could be seen by the number of Type 45s alongside in Portsmouth at any given time during the last few years. Historically the RN has never been a fleet of ‘harbour queens’ and today’s over-worked navy can ill-afford unreliable ships. HMS Daring entered service in 2009, it has taken more than 6 years to agree to deal with the problem and it will probably be well after 2020 before the work is completed. It is obviously dangerous from a seamanship and navigational point of view to suddenly lose propulsion at any time. It is even more serious when operating in a high threat environment as the ship would be a sitting duck.

Replacement of the WR-21 GTs is not a practical option. Instead additional or more powerful diesel generators will provide long-term redundancy and assurance that electrical supplies can be maintained in the event of GT failure. The good news is that the large Type 45 design has the space and reserve buoyancy to cope with larger or additional diesels. The rectification work on the six ships will be done one by one as part of the normal major refit cycle. This will extend the length of the refits but should not have an especially dramatic effect on frontline availability.

It is ironic that the RN is suffering with propulsion problems, having had a great history of propulsion innovation and success. The steam turbine was a British invention and in HMS Dreadnought (1906) was the first capital ship to use this leap in propulsive power. The steam turbine drove the majority of major warships for the next 60 years. HMS Amazon (1974) was the first all-GT warship and British engines were subsequently exported to many foreign navies. Much of the world-renowned expertise in naval GT design was derived from an obscure and secretive facility, the Pyestock National Gas Turbine Establishment at Farnborough which tested & developed marine and aero engines until it was closed in 2000. One of Pyestock’s last projects was some of the initial development of the WR-21 done in partnership with Rolls Royce and Northrop Grumman. Reliance on computer modelling signalled the end for Pyestock but with hindsight perhaps there is no substitute for ‘real world’ testing. It is interesting to note that recently Rolls Royce opened a brand new testing facility for the WR-21 and the MT-30 GTs (Which will power the QE aircraft carriers and Type 26 frigate).

There are growing signs that frustration with industry in the MoD has reached breaking point. The Type 45 propulsion problems are just one of many expensive problems with major defence contacts. The cost over-runs of the Astute class submarine have led to Whitehall creating a special project office to manage the Trident Successor submarines and failures will be met with harsher financial penalties. The surprise emergence of the alternative frigate programme, in addition to the Type 26, is also a sign of disillusionment with late, expensive and flawed offerings from BAE Systems.

Source
http://www.savetheroyalnavy.org/putting-the-type-45-propulsion-problems-...