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Combined steam and gas (COSAG) is a propulsion system for ships using a combination of steam turbines and gas turbines to power the shafts.
| Combined marine propulsion |
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CODOG |
A gearbox and clutches enable either of the engines or both of them together to drive the shaft. [1] It has the advantage of the cruising efficiency and reliability of steam and the rapid acceleration and start-up time of gas. This system was mainly used on first-generation gas-turbine ships such as the Royal Navy's County-class destroyer and Tribal-class frigate.
The Spanish aircraft carrier Dédalo also used it.
A steam turbine is a machine that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Charles Parsons in 1884. Fabrication of a modern steam turbine involves advanced metalwork to form high-grade steel alloys into precision parts using technologies that first became available in the 20th century; continued advances in durability and efficiency of steam turbines remains central to the energy economics of the 21st century.
HMS Hampshire was a County-class destroyer of the Royal Navy. Laid down, in March 1959 a couple of weeks behind the class leader Devonshire, she was classified as a guided missile destroyer, as the Sea Lords regarded the concept of the cruiser and big gun ship as discredited by the perceived failure of the Tiger class and the obsolescence of the heavy gun. The description of guided missile destroyer seemed more likely to win approval from the Treasury and Government for an adequate number of warships the size of small cruisers, which could play many traditional cruiser flagship and command functions, but had no armour around its gun and missile magazine.
HMS Kent was a batch-1 County-class destroyer of the Royal Navy. She and her sisters were equipped with the Sea Slug Mk-1 medium-range surface-to-air missile SAM system, along with the short-range Sea Cat SAM, two twin 4.5-inch gun turrets, two single 20mm cannon, ASW torpedo tubes, and a platform and hangar that allowed her to operate one Wessex helicopter. The County class were large ships, with good seakeeping abilities and long range, and were ideal blue-water ships for their time.
The Type 81, or Tribal class, frigates were ordered and built as sloops to carry out similar duties to the immediate post war improved Black Swan-class sloops and Loch-class frigates in the Persian Gulf. In the mid 1960s the seven Tribals were reclassified as second class general-purpose frigates to maintain frigate numbers. After the British withdrawal from East of Suez in 1971 the Tribals operated in the NATO North Atlantic sphere with the only update the fitting of Seacat missiles to all by 1977, limited by their single propeller and low speed of 24 knots. In 1979–80 age and crew and fuel shortages saw them transferred to the stand-by squadrons; three were reactivated in 1982 during the Falklands War for training and guardship duties in the West Indies.
HMS Mohawk was a Tribal-class frigate of the Royal Navy in service from 1963. She was named after a tribe of Native Americans located in southeast Canada and New York State. Mohawk was scrapped in 1983.
A diesel–electric transmission, or diesel–electric powertrain, is a transmission system for vehicles powered by diesel engines in road, rail, and marine transport. Diesel–electric transmission is based on petrol–electric transmission, a transmission system used for petrol engines.
Four destroyers in the United States Navy comprised the Cassin class. All served as convoy escorts during World War I. The Cassins were the first of five "second-generation" 1000-ton four-stack destroyer classes that were front-line ships of the Navy until the 1930s. They were known as "thousand tonners" for their normal displacement, while the previous classes were nicknamed "flivvers" for their small size, after the Model T Ford.
USS Makin Island (LHD-8), a Wasp-class amphibious assault ship, is the second ship of the United States Navy to be named for Makin Island, target of the Marine Raiders' Makin Island raid early on in the United States' involvement in World War II.
Air-independent propulsion (AIP), or air-independent power, is any marine propulsion technology that allows a non-nuclear submarine to operate without access to atmospheric oxygen. AIP can augment or replace the diesel-electric propulsion system of non-nuclear vessels.
USS Gwin (DD-71) was one of six Caldwell-class destroyers built for the United States Navy. She was in commission from 1920 to 1922.
HSwMS Clas Fleming was a cruiser-minelayer built before World War I for the Royal Swedish Navy. Completed in 1914, the ship performed limited neutrality patrols in the Sea of Åland and the northern reaches of the Stockholm Archipelago during the war. She was placed in reserve in 1917 to be modified to make laying mines safer and remained in that status until the beginning of World War II in 1939 to save money. Clas Fleming was activated for a short time that year to lay defensive minefields before she was began a reconstruction that installed an early version of gas turbines, the first ship to be so equipped. After her sea trials were completed in 1940, she was on active service for the rest of the war. Clas Fleming was again reduced to reserve at that time and did not leave the dockyard before she was stricken from the navy list in 1959. The ship briefly served as a target ship before being sold for scrap the following year.
The Farragut-class destroyers were a class of eight 1,365-ton destroyers in the United States Navy and the first US destroyers of post-World War I design. Their construction, along with the Porter class, was authorized by Congress on 29 April 1916, but funding was delayed considerably. Limited to 1,500 tons standard displacement by the provisions of the London Naval Treaty of 1930, the ships were laid down beginning in 1932 and were completed by 1935. After 12 years since the last of the previous class of American destroyers was commissioned, the Farraguts were commissioned in 1934 and 1935.
Combined diesel or gas (CODOG) is a type of propulsion system for ships that need a maximum speed that is considerably faster than their cruise speed, particularly warships like modern frigates or corvettes.
Combined gas turbine and gas turbine (COGAG) is a type of propulsion system for ships using two gas turbines connected to a single propeller shaft. A gearbox and clutches allow either of the turbines to drive the shaft or both of them combined. Marine usage of COGAG systems are similar to those found ashore.
Combined gas or gas (COGOG) is a propulsion system for ships using gas turbine engines.
Combined diesel-electric and gas (CODLAG) is a modification of the combined diesel and gas propulsion system for ships. A variant, called the combined diesel-electric or gas (CODLOG) system, contains the same basic elements but will not allow simultaneous use of the alternative drive sources.
The three Chester-class cruisers were the first United States Navy vessels to be designed and designated as fast "scout cruisers" for fleet reconnaissance. They had high speed but little armor or armament. They were authorized in January 1904, ordered in fiscal year 1905, and completed in 1908. In 1920 all scout cruisers were redesignated as "light cruisers" (CL).
Marine propulsion is the mechanism or system used to generate thrust to move a watercraft through water. While paddles and sails are still used on some smaller boats, most modern ships are propelled by mechanical systems consisting of an electric motor or internal combustion engine driving a propeller, or less frequently, in pump-jets, an impeller. Marine engineering is the discipline concerned with the engineering design process of marine propulsion systems.
The Topaze-class cruisers were a quartet of third-class protected cruisers built for the Royal Navy in the first decade of the 20th century. HMS Amethyst of this class was the first warship larger than a destroyer to be powered by turbine engines.
Integrated electric propulsion (IEP), full electric propulsion (FEP) or integrated full electric propulsion (IFEP) is an arrangement of marine propulsion systems such that gas turbines or diesel generators or both generate three-phase electricity which is then used to power electric motors turning either propellers or waterjet impellors. It is a modification of the combined diesel-electric and gas propulsion system for ships which eliminates the need for clutches and reduces or eliminates the need for gearboxes by using electrical transmission rather than mechanical transmission of energy, so it is a series hybrid electric propulsion, instead of parallel.