existing channel to Portsmouth to make it deeper and wider, and refurbishing the base’s jetties to ease access for both the Queen Elizabeth class and Type 45 fleet. Recent weeks have also seen Rolls-Royce
complete the latest components in the power and propulsion system it is supplying for the carriers. Te final batch of Michell thrust blocks and line shaſt bearings, which will support the rotating shafts that drive the ships’ propellers, were handed over in a ceremony at the Rolls-Royce facility in Newcastle. The forward motion created by the
rotating propellers is transferred through the two Michell thrust blocks, which are secured to the hull and each weigh more than 20tonnes, to move the 65,000tonne ships through the water. The twin propellers deliver around 80MW of power. Te propeller shaſts run approximately
one third of the length of the 290m ships, and Rolls-Royce has also completed the Michell line shaſt bearings, which support the weight of the propellers and rotating
shaſts along the hull of the ship. During operation, the bearings are designed to generate a film of oil between the bearing surfaces and shaſts on which the bearing loads are supported. In 2008, Rolls-Royce won a £96 million to supply a significant range
contract
of equipment to the Queen Elizabeth class programme, providing power and
BMT Isis validates approach channel design
As highlighted in this feature, the approach channel to Portsmouth naval base, which will be the home base for the new carriers, needs to be realigned and deepened to allow the carriers to use it. In March, BMT Isis Ltd, a subsidiary of BMT Group Ltd, announced the completion a project to validate BMT’s design for the approach channel, a design conceived to ensure that the Queen Elizabeth class aircraft carriers can transit it safely.
Having developed the design for Defence Infrastructure Organisation (DIO) six years ago, as well as completing initial validation work using desk-top simulation and peer review involving Royal Navy navigation experts, it was necessary to provide final validation. BMT utilised a full- mission simulator working in real-time with Royal Navy navigation experts in a realistic bridge environment. Working closely with the DIO and the Royal Navy, BMT provided the necessary computer model results, data handling and analysis for the study at the Navigational Training Unit of HMS Collingwood’s Maritime Warfare School. On completion, the Royal Navy personnel were happy with the proposed channel design and satisfied that it would allow the safe arrival and departure of the aircraft carriers at Portsmouth. Final validation was therefore complete. Ian Dand, Principal Consultant at BMT Isis comments: “Our particular role was to help the Royal Navy better understand how the vessels are likely to handle at low speeds and ensure the navigational process can be conducted as effectively as possible. “We defined the necessary parameters and tailored the simulator accordingly, so that the navigational characteristics of the aircraft carrier could be reproduced. This allowed the navigators to better understand the topography of the new channel, what aids to navigation were required and where they need to be placed, thereby improving confidence in the proposed approach channel design.”
Computer-generated impression showing HMS Queen Elizabeth in the approach channel at Portsmouth.
Warship Technology May 2012 27
propulsion systems to both vessels. Rolls-Royce is supplying the ships’ MT30 gas turbines, which at 36MW each are the world’s most powerful for marine use. In addition to the bearings and thrust blocks handed over today, Rolls-Royce is manufacturing propellers, rudders, stabilising fins and the entire low-voltage electrical system for both ships. WT
The last hull section of HMS Queen Elizabeth is due to arrive at Rosyth this autumn.
Feature 4
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