Durand de la Penne-class destroyer

The Durand de la Penne class destroyers are two guided missile destroyers operated by the Marina Militare, the Italian navy. The design is an updated version of the Audace class destroyers but these ships are larger, have CODOG machinery and modern sensors. Initially four ships were planned but the second pair were cancelled as Italy had decided to join the Horizon project.

Origins
This class is named after a famous naval diver who served in the Regia Marina during World War II, Luigi Durand de la Penne. He, together with other members of X MAS made the most successful human torpedo mission, damaging the British battleships Queen Elizabeth and Valiant in Alexandria, December 1941, with SLCs 'Maiale'.

These new ships were meant as very advanced destroyers, with an improvement over the previous types in almost every aspect of design. Because the ships in Marina Militare Italiana are seldom built from scratch (especially for economic reasons), it's worth considering the evolution of this project, starting by the first class of missile destroyers made in Italy. With progressive calls for better performances, this class evolved into the final design for the Durand de la Penne class destroyer.

The first step of this 'cumulative growth' was the Impavido class destroyers, the firsts DDG of the Marina Militare, but still a version of the Impetuoso class destroyers. The Impavido class ships were commissioned in the early 1960s, and they were roughly equals to the USS Charles F. Adams class destroyer. Both shared Tartar missile system, with an Mk 13 launcher, around 40 missiles and two Fire Control radars, all this was fitted in the aft of the ship. Both had also two single 127 mm guns, but American ships had these in single mountings and in a new model, the Mk 42, one at fore and the other at aft, while the Impavido made use of an older Mk 38 dual turret.

One difference was the secondary weaponry. While both had lightweight torpedo launchers, the rest was different. Adams had an ASROC launcher, dedicated to ASW tasks, to help counter the growing number of Soviet submarines. Impavido did not have such systems, but instead had four model MM (Marina Militare) 76 mm guns. In the Mediterranean there was always the danger of air attacks as the main threat to ships, and this usually led to the construction of many Italian warships with a heavier short-range air defence armament than normal. This is not true for oceanic ships, less endangered by aircraft and more by submarines. The relative danger to the Royal Navy in the Falklands War was due, mainly, to the excessive optimization to fight Soviet submarines, so after this war the RN made many improvements in the air defence field - including installation of many Close-In Weapon Systems.

In service the MM guns were not considered satisfactory, despite having decisive improvements over the older American 76 mm guns. Reliability left a lot to desire, while the lack of a totally automatic mode of fire proved a disadvantage. Not coincidentally, no first generation 76 mm Italian guns had any export success.

In the early years of the 1970s, a new pair of destroyers was commissioned, the Audace class destroyers. They were built somewhat bigger, to accommodate the solution to one of the most serious weakness of the previous Impavido class, the lack of an ASW helicopter hangar. Agusta had navalized the Bell 212 helicopter and two of these were accommodate in a hangar, practically framed with the Tartar launcher, in the same relatively small superstructure.

The guns remained in the same location, number, and caliber, but they were totally new models, developed in those years: the Otobreda 76 mm Compact and Otobreda 127/54 Compact. The latter was and is a very powerful weapon, with a rate of fire of 40-45 shells per minute, and projected to be an efficient anti-aircraft weapon. They have a greater maximum elevation and higher rate of fire than their rough equivalent, the USA 5"/54 caliber Mark 45 gun, but also have higher weight and volume requirements. Two were in fore positions, at different heights to shoot at the same target. They were controlled by the new RTN-10X radar, an advanced type for its times that was also adopted by the Royal Navy for some of its ships.

Midship there were four Otobreda 76 mm cannons. They were and are reliable, fast-firing and light weapons, capable of sustaining a rate of fire of 80 rounds a minute and actually the most widespread weapon of its class (also because there are practically no competitors). These guns also had fire control radars, one for every flank. Towards the aft of the ship there was the Tartar launcher with the two Agusta helicopters able to make ASW and limited anti-ship tasks. For ASW this ships also had both light (two triple 12.8 inch) and heavy (two dual 533 mm) torpedo launchers, and Whitehead A.244 (light) and A.192 (heavy) torpedoes, 12 for each type. These were very modern and advanced in their days and the heavier type were able to be used also against ships within their 20 km range. So the Audace class had two different types of guns and two different types of torpedoes, a characteristic without parallel in other navies.

The class was not perfect however. Despite the powerful six-gun armament, none of them was able to fire directly aft of the ship, leaving this quarter only to the Tartar missile system, a weapon not meant to provide close air defence (this will be rectified with the de la Penne class). The artillery was also very good employed against aircraft, but somewhat lacking against missiles (despite the very short time required to fire after the alarm was given), while there were no SSM missiles on board, to strike naval target over the horizon (except the use of the obsolete AS-12 missile from helicopters), so this role could only be accomplished by guns within the 20-25 km range of the gun systems.

The powerplant was still a steam-turbine type, quite bulky and obsolete, but their 73000 shp were enough to achieve around 33 kn and quite a good range. The ship's dimensions were again a bit cramped, accommodating all the equipment and the crew (380) on board a relatively small hull. The heavy load of ammunitions was a serious potential danger for the ship. Also because the superstructure was built of light aluminium alloys, prone to burn in a heavy fire.

At the end of the 1980s, while the Impavidos were phased out, the Audaces were modernized. The second 127 mm gun (in 'B' position) was replaced by an 8-round Albatross/Aspide system. Eight long range Otomat missiles were fitted at midship, between the four 76 mm guns, now replaced with the Super-Rapid sub-type, which were much better fitted against missiles. Heavy torpedo were removed and overall the capabilities were improved in AAW and anti-ship tasks.

Audace was one of the best, if not the best destroyer of its time. There were some shortcomings to face however, and technical evolution to consider, while Impavido were too old to be considered good for other updates. So in the 1980s development of a new class of destroyers was begun. Initially known as 'Audace migliorata' class, or Class Animoso, then they had the final name of de la Penne Class.

Initially there were projects for three 40 mm DARDO CIWS, but these were then replaced by Super-Rapid 76 mm guns which were considered superior. This and the partial redesign of the ship to gain a reduced RCS were the main alterations during the engineering.

The power-plant was planned with new generation machineries: a CODAG configuration, diesel for cruising, and gas-turbines for high speed. This provided more endurance, less weight, with less space needed, less danger (no boilers) and were more responsive than steam turbines. Superstructure components were made mainly of steel and not the flammable aluminium. Some armour was added as well in the vital sectors. All this caused an increase in displacement, from the original 3,600/4,500 tons of Audace, to 4,500/5,400 tons. Overall dimension were also increased.

General project
The Durand de Le Penne is an escort and combat class ships, able to operate in every combat condition, and especially devised to survive to heavy missile and aircraft attacks. Its construction is made almost totally with steel; the structure is a continuous deck with a low, large stern, to accommodate the helicopter's force. The fore hull is very pointed, with a very pronounced sea-cutter structure. The superstructure consists of two blocks, relatively low and wide, both with a high, antenna mast with a triangular cross-section for all the electronic. The engines exhausts are in two groups, one for each superstructure: the aft has two exhausts flank to flank, slightly inclined. Then there is the Standard missile system and finally the helicopter's facilities.

The ship itself is built to be much more difficult to sink by enemy action than the previous types, with many bulkheads and anti-fire systems. Many of the main communication lines and computers are duplicated, and there is a NBC system for the crew. Stealthness is partially applied, with reduction of RCS, heat, noise and magnetic signatures.

The speed, given by a CODAG system, is high (31knots) but not so high like previous Audace, also because the modern ships seldom has need of speeds over 25 kn. The endurance, automation and economy are more important, as well as the compact design of this power-plant. The powerplant is based on two General Electric LM-2500 gas turbines, one of the most successful naval turbines, and 2 diesels. One of each are linked with one shaft fitted with a propeller with 5 blades. The entire propulsion system is controlled remotely; no crew is needed inside the powerplant section in normal situations.

As for vulnerability and general characteristics, these ships, while prestigious, were a bit smaller than was actually needed. In fact, the weapon (and explosives) concentration is very high. In the foredeck, in less than 20 m there are 3 medium caliber guns, with over 200 shells just behind the deck ready for use, surrounding the Aspide system, that has 16 or 24x230 kg missiles just below the deck. The aft superstructure is equally heavily armed, with a gun, 2 helicopters and 40 SM-1/2 missiles (the combined weight of the latter 24 tonnes, with over 1 T high-explosive), plus the ASW torpedo stores (several Mk 46 or A244 torpedoes), in less than 25 m. Also because of this, the crew complement, at 380, is larger than as in other modern ships: a large crew is absolutely required to control damage or fire.

Although the class is criticized for the small displacement related to their equipment, the previous Audace were even more cramped: they were 900t lighter, quite smaller, with a bulky powerplant; however, in their latest update they had the same armament, plus an extra Super-Rapido gun (4 instead of 3).

Another criticism aimed at these ships is the lack of vertical launchers, not purchased by Marina Militare because of financial constraints, choosing instead to modernize the Impavido's launchers for de la Penne new destroyers. So de la Penne are the last and maybe the most powerful of the "conventional missile destroyers". this came at a cost, however: 1500mld. Lire for both these ships (1981-1993 program), partially because a large production run could not be afforded by Marina Militare for such big ships (so no economies of scale were obtained).

Weaponry
These ships have an overall shape that appears as large, low, and aggressive. A direct consequence of their armament and the special features of sloped surfaces (because of stealth principles).

Weapon systems include a guns battery scattered over all the ship, which helps to make its profile well recognizable. As anti-aircraft equipment, there are 6 weapons, of four different types: Standard SM-1 launcher Mk13, Albatross-Aspide, 1 gun Compatto 127/54 mm, 3 guns Super-Rapid of 76 mm caliber. All these weapons covers all the horizon, giving an air defence able to stop quite heavy attacks, especially from the front, because the majority of these is placed on foredeck.

If the Standard missiles, with their 2 SPG radar are dedicated to the air defence at longer ranges, the rest is a medium-short range weaponry. Having Aspide/Sea Sparrow launchers, these ships are one of the fews that possessed both these systems (standard and Sparrow class missiles). Aspide are very advanced missiles (with monopulse guide from the start of service, 1977), but they are almost identical to Sea Sparrow. In fact, these latter were mass-produced by Alenia before the start of the Aspide, so this experience was a cleary advantage to project such new missiles, but all the systems inside (warhead, guide, engine) were new and much improved respect to the old Sparrow-E, and roughly equal to Sparrow-M, not yet available in 1977. 16 missiles are in the magazines, but a Riva-Calzoni system can load quickly 4 at once in the 8 cell launcher, so these missiles are quickly reloadable (the Sparrow launchers have manual reloading).

The Compatto 127 mm gun is that dismount by Audaces DDG's when Aspide was fitted. It was modernized before its re-utilization on de la Penne.

The OTO Super-Rapido are powerful weapons for its caliber, and despite CIWS defence is normally delegated to smaller calibers, they have mainly this task. They can shoot 120 RPM, 6.3 kg shells with sophisticated fuses, and engage at 6 km even anti-ship missiles. It is claimed by OTO that these guns can engage until 4 missiles before they reaches the ship. In every case, they have whipped the contenders like Dardo 40 mm guns and the new Myriad, 25 mm gatling CIWS (that had not awarded any commercial success), despite its 10.000 rpm. Four RTN-30 radar-optical system controls such weapons, 2 fore and 2 aft, so no all the weapons can shot simultaneously at different targets.

As anti-ship weapons, there are Otomat, missiles with a very long range (180 km or more), with mid-course guide by AB-212s, sea skimmer capability and a 210 kg warhead. They born as Franco-Italian program, but only Italians ordered them (and a dozen other navies as well) while French navy ordered only the national Exocet, despite a much shorter range. The main characteristic of OTOMAT, the long range, ironically, is achieved thanks to Microturbo engine, the main French effort for this missile. The MILAS version, an ASW missile with a light torpedo, was developed for ranges until 40 km, but still not acquired by French navy despite the needing to replace the MALAFON missile. 8 missiles are placed at mid-ship, between the two main superstructures.

The aft superstructure has a very concentrated set of weapons (just like foredeck). In the hangar superstructure there are 2 AB-212ASW, 1 Super-Rapido gun, and the 40 missiles of the Mk 13 launcher, probably now utilizing SM-2MR missiles, an eventual big improvement over the original in almost every respect. Standard missiles are capable to attack also naval vessels.

As electronic systems there is a complete suite with dedicated systems for all the tasks. As radar, there 11 different system. There are:


 * SPS-40 tridimensional radar over one of the 2 triangular trees, the aft one (US built, 300 km range, S band)
 * the other main radar is an SPS-768 bi-dimensional (Alenia built, roughly the same range, D band), that is placed over the turrion, then, there is a radar dedicated to look about low-flying aircraft and ships, 160 km range (S), in the forward tree. Perhaps this unusual accommodation was due to the excessive weight in high, if the two main radars were both placed on the trees. It is linked with Dardo FCS. The forward tree has a quantity of small electronic antennas, as communications, datalinks, ECMs.
 * There are also a surface radar SPS-702, X band, last version of a type quite successful and with all-solid electronics. Finally there is a navigation radar, with X band, forward tree.
 * 6 FCS radars are totally presents, with two Standard missile radars AN/SPG-51 D (G/I band) with a FCS Mk 74 Mod.6. 4 DARDO-E are used for artillery and Aspide use, K-band (plus TV, IL, laser and IR sensors)
 * a DE 1164/1167 sonar with (differently by Audaces) an immersion (VDS) DE 1167 element
 * an ECM set Nettuno, one ESM, 2 rocket launchers DAGAIE (of French construction, replacing the previous SCLAR systems of Breda, 10 tubes with 330 mm caliber and 10 km range, IR-radar decoys)
 * a complete set of communications and controls, included the combat system called IPN-20 by the manufacturer Alenia, and SADOC-2 by Marina Militare. It's a computerized elaboration system, that take cares of all the tactical information and the communications with others platforms. It had 10 consoles with one operator each (Garibaldi carrier had a SADOC with only one console more than de la Pennes).

Service
Durand de la Penne  was in service with Marina Militare Italiana starting from 1993, followed one year later by Mimbelli. These two ships, together with the two old Audace, were the bulk of Italian navy's air defence, especially before that AV-8 Harrier, armed with AMRAAM, began fully operational. But even so, these were available only in Garibaldi task force. These missile destroyers have performed well as command ship in several deployment even over Mediterranean sea, and the last of their missions was related to the Italian peacekeeping force in Lebanon.

At the time the best non-AEGIS air-defence ships, de la Penne have important roles in Italian navy. Now that Audace are decommissioned, de la Penne will remain the only missile destroyers (and the only ship with area defence-missiles) for some time, until the new Horizon will be operative. Although they are still quite young ships, it does not seem that they will be updated significatively with new air defence systems. Like almost all Italian ships, they were designed with a modern and effective armament, but retained the same for their entire operative lives.

Minor changes are or will are made: the compatibility with one EH101 heavy helicopter or 2 NH90 (enhancing the helicopters capabilities, now still on AB-212s) equipped with new sensors, ASW torpedoes A.290 IMPACT and the Marte Mk 2 anti-ship missile, over the new ASW missiles MILAS, and quite obviously, continuous updates on the computers and electronic systems, that brings much improved performances even if externally there is almost no difference to notice.

Another important improvement will be the adoption of guided ammunition for the guns: Vulcano projectile for 127 mm, with an extended range of 70–100 km, meant as coastal bombing, is a quantum leap forward compared to the traditional artillery rounds (similar to a new models developed in USA), while DAVIDE (guided) or DART (sabot projectile) will further enhance the already very powerful anti-missile defence of these ships. There are no plans, currently, to equip them with EMPAR/ASTER missile systems.