Guest blogger
David Downs
Aircraft Carrier Alliance Engineering Director
As work on Queen Elizabeth enters its final phases, Prince of Wales is nearing the crucial point where it can be floated.
The project to deliver the Nation’s Flagships, the two aircraft carriers Queen Elizabeth and Prince of Wales, continues to gain momentum at Rosyth. The Aircraft Carrier Alliance (ACA) is focused on the significant project milestone of getting the ship staff of HMS Queen Elizabeth moved on board the ship in the summer so that they can work and train on board. This will allow the ship staff to be ready such that when the commissioning activities are sufficiently mature they will be in a fit state to take the ship to sea for sea trials around the end of the year.
There are four principal activities that the ACA are undertaking leading up to Ship Staff Move On Board (SSMOB) and Ready For Sea Date (RFSD).
Power and Propulsion
The power and propulsion system generates electrical power at high voltage (11kV) which is used to propel the ship via the four propulsion motors and also transformed down to low voltage (440V, 115V and 230V) for running the mission systems and the hotel services. Clearly the power and propulsion system and the Integrated Platform Management System which controls it are fundamental to making the ship habitable and capable of going to sea. As might be expected with a complex first of class vessel there have been several technical challenges to be addressed in commissioning the power and propulsion system, but the ACA have now run all four Wartsilla diesel generators at up to 100% power. Both Rolls Royce MT30 gas turbine alternators have been run at up to 50% power with the power being absorbed through a substantial load bank ashore.
The propulsion drives and propulsion motors have been commissioned and the propeller shafts have been turned at around 100 rpm. At present “brake blades” which absorb shaft torque without producing thrust are fitted to the propeller hubs. This allows around 50% of full power to be absorbed into the water of the fitting out basin and in combination with the load bank enables the power and propulsion system to be tested at full power before the ship leaves the fitting out berth. The brake blades will be removed and the actual propeller blades will be fitted underwater by divers prior to the ship going on sea trials. Although individual blades have been changed on commercial ships under water this is believed to be the first time that a complete set of blades have been changed in this fashion. Jigs and fittings have been designed to aid the divers in handling the blades and the whole evolution has been trialled using one of the second ship’s propeller hubs submerged on the synchrolift in Rosyth.
Mission Systems
The Mission Systems that will provide navigation information, tactical picture compilation, air traffic control, landing aids and command and control together with internal and external communications is progressively being set to work. The Integrated Network Environment running on a network of fibre optic cables distributed throughout the ship has been set to work and is being used to share information around the ship including running the Integrated Platform Management System. The Medium Range Radar fitted to the masthead of the aft island is now “burning and turning” and recording tracks which is a major achievement. On the ship’s bridge the consoles are being populated with processors and screens and the Integrated Bridge and Navigation system is starting to take shape.
Chilled water is the life blood of the ship providing cooling to the air conditioning system throughout the ship and direct cooling to much of the electronic equipment. The chilled water ring main is complete and has been being supplied with chilled water from ashore. The first few of the ship’s chilled water plant are now being brought on line. As expected with a first of class complex warship some technical challenges remain with the plant but the ACA Commissioning team supported by Ship Staff and the ACA Engineers are working through and eliminating the issues as they arise.
Flight Deck Coating
There are four and a half acres of flight deck on top of a Queen Elizabeth Class aircraft carrier, which has to be coated with material that will protect the deck from the weather, withstand the high temperature and pressure exhaust efflux from the F35 Jet aircraft, provide the required coefficient of friction for the aircraft undercarriage and contain the flight deck markings. Moreover, just to make it a bit more challenging, this coating has to be applied at an exposed location in Fife in Scotland, which is not renowned for good weather.
Conventional paint based coatings will not survive the aero thermal environment when the F35 jet efflux is directed down at the deck during a vertical landing, therefore a thermal metal spray solution has been developed by Monitor Coatings which has been proved to withstand the environment during laboratory trials, and to meet the required coefficient of friction through rolling drum trials. However it has been necessary to demonstrate that this coating can practically be applied to large areas of the flight deck. A trial spot forward of the forward island has been used to prove the application of the technology, including the tenting and containment needed to ensure that the environmental conditions are suitable for the application. Testing this containment during one of the wettest and stormiest winters on record has certainly been an exacting test. Application to the trial spot has proved very successful and the team are now moving on to applying the coating to three other landing spots on the port side of the deck.
If the thermal metal spray coating proves to be as successful as expected, it will then be extended to a larger area of the deck. The remainder of the flight deck will have a conventional CAMREX paint based coating applied. The environmental protection and containment is currently being erected to allow this to proceed.
While undertaking a vertical landing the aircraft has to traverse the port side catwalk at low elevation, therefore as well as protecting the deck there is a need to protect equipment located in the catwalk from the jet efflux. One particularly important but tricky piece of equipment to protect are the liferafts. The protection of these needs to be designed so that it will not impair the deployment of the liferaft in an emergency and particularly the hydrostatic release mechanism that will enable the liferafts to deploy and float free if submerged. Bespoke hinged shields with a hydrostatic release have been designed. These have recently been successfully tested in the water of the non-tidal basin at Rosyth to prove that they will operate as required.
Compartment Completion Inspections (CCI)
There are over three thousand discrete compartments on a Queen Elizabeth Class aircraft carrier, each one of which has to be inspected by the ACA team including the MoD client before being declared complete and ready to be handed over to ship staff. The required rate of CCIs to support SSMOB and RFSD is quite challenging. The team have just completed the one thousandth CCI and the first of the ship’s compartments have recently been handed over to the ship staff so that they can begin training and working on board. The aim is to hand over pretty much the entire ship below the hangar deck to ship staff in the summer so that they can start to live on board. This will require the final commissioning of amongst other things the galley compartments. Progress towards this milestone is currently very good.
While the ACA’s Ship 01 Delivery Team are focused on commissioning Queen Elizabeth afloat in the non-tidal basin, the Ship 02 Delivery Team are pressing on with the build of Prince of Wales in the build dock at Rosyth. All the block construction work at the various shipbuild sites across the country has now completed and all but the last couple of sponson blocks have been assembled onto the ship. Structural completion is very rapidly approaching with the next significant event being “drop stern” which allows the aft end of the ship to take up the shape it will have when afloat and is the precursor to aligning the propeller shaft bearings and installing the shafts.
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Inside Prince of Wales the chilled water ring main in the forward part of the ship has been completed and many of the compartments are nearing a state of completion such that when walking around it looks to be in a very similar state of completion to Queen Elizabeth. On the outside the hull painting of the forward end has been completed, the anchor chains installed, and in many respects the ship is looking ready to be floated up.
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David is employed by BAE Systems, and is responsible for all the engineering work being carried out on the QE Class programme. Previously, he was design manager for HMS Ocean, Albion and Bulwark, and was chief engineer on the Type 45 Destroyer programme
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