dissabte, 16 de març de 2013

NAVY'S NEW CARRIER PRACTISES CRUCIAL REFUELLING USING SCALE MODELS*





















The Navy’s new carrier has successfully carried out its first refuelling in the water – in miniature.
Two highly-accurate one-tonne scale models of HMS Queen Elizabeth and future tanker RFA Tidespring have been tested in Europe’s largest indoor water tank in Gosport to determine how the two ships can sail safely in company.
Key to any future operations by the carrier – the largest warship ever to sail under the White Ensign – will be sustaining her thousands of miles from home.
For that she’ll need to conduct a RAS – replenishment at sea – on a fairly regular basis with a tanker or support ship of the Royal Fleet Auxiliary, whose ships provide crucial sustenance to Royal Navy vessels around the world daily.
Hand-in-hand with construction of Queen Elizabeth and her sister HMS Prince of Wales is the construction of a new generation of Fleet tankers – four Tidespring-class ships of 37,000 tonnes, entering service from 2016.
The basic design for the Tidesprings is almost complete – and key to that design has been testing how they perform when working with the future carriers.
When the two ships sail together to conduct a replenishment – fuel, water or dry supplies such as spare parts or fuel transferred by jackstay – they are subject to hydrodynamic forces which can drive them apart, or pull them together – both of which are highly dangerous.
So understanding these forces is key to safe operations.
Two 1:44 scale models – the 37,000-tonne 200m-long (659ft) tanker has been reduced to 4.5m (15ft) in length, while the 65,000-tonne HMS Queen Elizabeth has been shrunk from 284m (931ft) in length to 6.45m (21ft) – were built and taken to the enormous ‘ocean basin’ test tank, owned by defence research firm QinetiQ.
The tank in Haslar, Gosport, is 122m (400ft) long, 61m (200ft) wide and 5.5m (18ft) deep – over 15 times more water than in a typical Olympic-sized swimming pool – and can simulate both calm and rougher seas.
Whilst the tank is regularly used by the maritime community, this is the first time that two new ships have been tested for RAS operations.
“The RFA ships will have to keep station using the Queen Elizabeth-class as a guide during RAS,” explained Cdre David Preston, head of RFA Engineering.
“This will take great skill and concentration for long periods in very challenging conditions – so any analysis we can undertake early will provide comfort that the replenishment at sea capability can be met with the new ships.”
Tests in the Haslar tank were carried up to a simulated Sea State 6 – very rough seas, with waves up to 6m or 20ft high – and the two models also practised emergency breakaways and engine failures.
Once all the data has been gathered and analysed it will be used by the RN and RFA to draw up the guidelines for safe operations when Tidespring joins the Fleet in 2016.
* Notícia publicada al web de la Royal Navy. Les operacions de reaprovisionament al mar són un autèntic prodigi de l'enginyeria i el talent humà en general. Sabedors de la importància que tenen, els britànics ja les practiquen en models a escala pels seus futurs portaavions. Fets com aquest marquen la diferència.

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