Caio Duilio is the result of a Horizon-class frigate research program that has been jointly developed by France, Italy and the United Kingdom since the 1990s.
At present, the most powerful anti-aircraft destroyers of NATO nations consist of three groups: The Aegis destroyers of Spain and Norway, including two variants of the Arleigh Burke-class destroyers, Alvaro de Bazan and Fridtjof Nansen. Next is the German Navy Sachsen-class destroyers, based on the F123 Brandenburg-class predecessor but designed to increase radar scattering capabilities and deal more effectively with negative hydro-reconnaissance equipment. Finally, the Horizon-class destroyers are in service with the French Navy and the Italian Navy. Currently, the French Navy has two Horizon-class destroyers, named Forbin and Chevalier Paul. The Italians own two warships, Andrea Doria and Caio Duilio. Although the number of Horizon-class warships is relatively small, these ships are playing an important role in the French Navy and the Italian Navy.
In 1982, the United Kingdom, France and Italy began a multinational cooperation program, called Common New Generation Frigate, to create a new generation of air defense destroyers equipped with PAAMS air-defence missile systems.
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Almost immediately after the joint venture was launched, there were different requirements for each country. France wanted an anti-air warfare warship to escort its aircraft carrier. They only need warships with a relatively close range, because the French aircraft carrier Charles de Gaulle was able to defend itself quite well. The Italians only needed anti-aircraft destroyers with the same capabilities as France. In Mediterranean waters, Italian warships will operate with the support of the Italian air force, or because the task of the new warship will only be to escort the small carrier Cavour of Italy, the Italy is also only needs fleet defenses on less hostile waters.
The British military doctrine differed, requiring a powerful destroyer capable of defending a fleet operating in a hostile area, at least defending the British fleet patrolling the entire Atlantic Ocean. Then, in 1999, the British contractor announced withdrawal from the project to pursue its own design, creating the current Type 45-class destroyer. Some experts believe that the Type 45 class, later equipped with the PAAMS missile system, benefits from British investment in the Common New Generation Frigate project.
France and Italy continue the cooperation project, each order 2 warships. Caio Duilio was one of Italy’s two Horizon-class warships, the Italians called the Orizzonte. Caio Duilio joined the Italian navy on March 3, 2009, was named after the 3rd century BC Roman leader, Admiral Gaius Duilius, Caio Duilio in Italian, who defeated the mighty Carthaginian fleet.
The Horizon class ships are officially referred as frigates. However considering their size and powerful armament these ships are clearly destroyers. These are called frigates purely for political reasons. These vessels have enhanced stealth features with significantly reduced radar cross section and noise levels.
Caio Duilio has a full load displacement of 7050 tons with a length of 152.9m, a beam of 20.3m and draft of 7.6m. The ship is configured for rapid deployment and extended range and endurance and can carry sufficient fuel, water and stores for an endurance of 45 days at sea between replenishments.
The ship was designed to be as little detectable by radar as possible, by using stealth technology for the hull and superstructure. Sea-keeping in unfavorable weather conditions is granted by two pairs of stabilizers. The acoustic signature was also reduced with an appropriate choice of machinery and engineering solutions and verifying the intensity of the radiated noise, since the design phase. Equal attention has been directed in the infrared signature branch, by lowering the temperature of engine gases through coaxial exhausts.
The ship’s propulsion system is configured in a combined diesel or gas arrangement with two GE LM2500 gas turbines rated at 20.5 megawatt each and two SEMT Pielstick diesel engines rated at 4.32 megawatt each. The engines drive two shafts with constant-pitch propellers. The ship’s complement consists of 230 staff including Security and Flight teams, it can house up to 255 personnel.
The main radar is the EMPAR phased array multi-purpose radar operating at G-band, it is arranged at the top of the forward mast in a large round radome. It counters different threats such as high diving and sea skimming missiles, aircraft and helicopters and any kind of vessels. The maximum range of the radar is about 150km. There is also Thales S1850M air and surface search radar, operating at D-band is mounted at the top of the aft mast. The Selex RASS surface search radar, covering E and F bands, is mounted on the forward face of the mast. The Selex SPN753 navigation radar operates at I-band from 8GHz to 10GHz.
The ship is also equipped with the hull-mounted TMS 4110CL sonar which operates at medium frequency in active search and attack mode. This is a high performance sonar that provides effective anti-submarine capability together with self-protection against torpedo threats and underwater obstacles.
The electronic warfare suite is 2 Radar Jammers, 2 Oto Melara SCLAR-H decoys launcher system for chaff and flares. The radar electronic support measures component features very high sensitivity, very high accuracy direction finding and broadband digital receivers. The vessle is also equipped with a SLAT torpedo defence system.
The ship’s armament consisted of three OTO Melara 76 mm Super Rapid guns are installed as a pair on the foredeck immediately forward of the bridge and a single gun installed on the hangar overlooking the helicopter deck at the aft of the ship. Also there are two Oerlikon 25 mm cannons for engaging small surface targets, are installed one to port and one to starboard. In 2018, the ship was fitted with two more Sitep LRAD Mass CS-424 acoustic guns.
The frigate is armed with 2 twin launchers for Eurotorp MU90 lightweight torpedoes. MU90 has a directed energy warhead and a range of 12,000m at maximum speed and 25,000m at minimum speed. The Caio Duilio is fitted with a 48-cell Vertical Launch System for a mix of Aster-15 short range and Aster-30 medium range surface-to-air missiles. This system is installed immediately forward of the two guns towards the bow deck. Anti-ship capability comes from two quadruple launchers for the MBDA OTOMAT Teseo Mk.2A surface-to-surface missile, which has a range of up to 55km.
The Italian frigate is designed with a helicopter deck and a hangar with full service for a single helicopter, it could be AgustaWestland AW101 or NHIndustries NH90. This helicopter can be used for long-range anti-submarine warfare, search and rescue, utility and other roles.