Luigi Durand de la Penne class destroyer

Italy Day !
The last destroyers (so far) of the Marina Militare had been designed at the dawn of the cold war: The Durand de la Penne class. These two two guided-missile destroyers were a considerably enlarged version of the 1970s Audace class, updated with diesel and gas turbine CODOG machinery, much more modern sensors and extra capabilities. Four ships were planned but the second pair was cancelled as Italy joined the Horizon project which led to the successful FREMM design. Built by Fincantieri between 1989 and 1992 they were in service as cornerstone of the surface fleet until the lead ship, Luigi Durand de la Penne was recently decommissioned in last October. The last page of European cold war naval development is closed.

Development

Evolution of Italian guided missile destroyers

New guided missile destroyers were planned to replace the Audace class already in the early 1980s. They were planned as very advanced destroyers, with a serie of improvements over the previous types in almost every aspect, but were not built from scratch notably for economic reasons as four were planned, and rather were conceived as a simple evolution of the previous Audace class, first class missile destroyers with progressive calls for better performances. It evolved in the 1980s into the final design for the Durand de la Penne class destroyer, validated in 1988 with orders made in 1989. It was time as Audaceand Ardito has been launched in 1971 already.

D570 Impavido after modernization in 1983. She was the Italian equivalent to the Charles F. Adams

They evolved from the 1960s Impavido class, first Italian guided-missile destroyers, themselves evolving from the gun armed Impetuoso class. The Impavido class were roughly equivalent to the US Navy Charles F. Adams-class with the same Tartar missile system and Mk 13 launcher, two single channel Fire Control radars and two single 127 mm (5 in) guns in Mk 38 dual turret. They also had lightweight torpedo launchers but differed in others points such as the absence of an ASROC launcher, but four model MM 76 mm guns to deal with air attacks, as the threat was judged superior in the confinred of the Mediterranean compared to ocanic vessels. Reports from the Falklands War showed that excessive optimisation to fight Soviet submarines urged the need for better airborne or sea-borne anti-ship missiles and air attacks, prompring the adoption of Close-In Weapon Systems.

The previous Ardito (Audace class) after modernization in 1987

The MM guns had issues of reliability and lacked a full automatic mode. In 1969, the Audace class were commissioned with a very different design, somewhat larger, to accommodate lack of an ASW helicopter hangar, in that case a pair of Bell 212 helicopter, framed with the Tartar launcher. The gun armament remained generous, even larger than usual destroyer designs of the time, and with totally new models, which adressed all previous issues, such as the Otobreda 76 mm (3 in) Compatro and Otobreda 127/54 Compatto (compact). The latter was still very powerful, with a rate of fire of 40–45 shells per minute, at last an efficient and versatile AA weapon with greater maximum elevation and higher rate of fire notably than the US 5″/54 cal. Mark 45 traded for higher weight and volume, controlled by the new RTN-10X radar, an advanced type for its time.

This artillery was completed four Otobreda 76 mm cannons, very fast automated and reliable (80 rpm) and well exported abroad (in fact it became a best seller armong Euro artillery types). They all had fire control radars and aft was the Tartar launcher and an ASW panoply with the two helicopters and triple 12.8 inch, heavy 533 mm torpedo launchers. This combination was very unique and well regarded for their tasks at the time. The only critic was that Italian budget did not allow more than two of these. Other issues appeared while in service, as despite their generous six-gun armament, none could fire directly aft, leaving this sector to the Tartar launcher, unable to provide close air defence.

The light guns were also deficient to correctly adress incoming missiles, mostly in volume of fire rather than accuracy. Also the Audace class lacked anti-ship missile on board, to strike naval target over the horizon. Only the helicopter could bring the short-range AS-12 missiles to bear, making them very vulnerable platforms. The main Gun was to adress this issue the old way from 20-25 km (16 mi) range. By NATO standard a destroyer should always be capable of adressing all quarters threats, surface, undersea, and air, both at long (beyond the horizon), medium and close ranges. The same was required of cruisers, so some tolerance in shortcomings was granted here.

The powerplant of the Audace class and their old fashioned steam-turbine type was criticized in the 1980s as bulky and obsolete, with the only advantage of pocuring them with 73,000 shp (54,000 kW) enough for 33 knots (61 km/h) and still a good range. Dimensions were seemed unsuffucient as well, on the long run with addition, they appeared cramped and automation was not optimal, resulting in a crew of 380. The heavy load of ammunitions, spread along the ships and unprotected, was also a serious potential danger. At last the aluminium alloy superstructure was a consistent fire hazard.
So around 1987, just as the Impavidos were phased out, the Audaces were modernised and their second 127 mm (5 in) gun was replaced by an 8-round Albatross/Aspide system for air threats, eight long range Otomat missiles were fitted amidship for the long rage surface threats, while the four 76 mm (3 in) guns were replaced by the Super-Rapido which was capable of adressing missiles. Heavy torpedoes were removed and the latest model of Helicopter adopted whereas all electronics were obverhauled. These made them arguably among the best destroyer classes of their time, albeit still some shortcomings existed.

Design of the Audace ‘migliorata’ class

Since the Impavidos were juged way too old for updates around 1985, development of a new class of destroyer started under the name Audace ‘migliorata’ (improved) class, and called Animoso to follow popular destroyer names of WWI and WW2. However given their cost and status as well as political considerations they eventually received name, as more important ships in the Navy:
Luigi Durand de la Penne was a famous WW2 diver, which as part of X-Mas “spec ops” unit managed to “sink” Queen Elisabeth and Valiant in the port of Alexandria (they were write offs in Dec. 1941 for several months, a just return for Taranto in 1940). F. Mimbelli was the commander of torpedo boat Lupo, which fought the entire Force D (seven RN ships) in the Battle of Crete, protecting a convoy and later commanded a successful MAS unit in the black sea, rear and vice admiral postwar.
Initially the first design called for three 40 mm (2 in) DARDO CIWS, replaced by Super-Rapido 76 mm, considered superior. The partial redesign of to gain a reduced radar ross section were the main alterations in this early the engineering as well as a stretching of the hull. In the last design it reached 147.7 m (485 ft) overall instead of 140.7 m (461 ft 7 in). It seems not a wide stretch, but the superstructures adopted a very different, lower design due to the swap from aluminium to light steel and other fire proof alloys cause the silhouette to look ever further stretched down.

The power-plant was another big change as fore the first time a CODAG configuration was t be installed, with diesels for cruising, and gas-turbines to reach higher speed, provided more flexibility and endurance, less weight, freed weight and space and improved safety. At last to address the ammunition storage issue, some armour was added in vital sectors. All this increased displacement, from the original 3,600/4,500 ton (Audace) to 4,500/5,400 tons. Almpst a 1,000 tonnes increase for 7 meters (23 ft) in extra lenght, 1,4 meters in extra beam (4.6 ft).

Design of the class

The Durand de Le Penne were designed as escort and combat ships, designed to provide an all-rounds, all-ranges , all-threat protection to a task force or battle group, and to survive to heavy missile and aircraft attacks. Construction for all steel but with alloys for the superstructure.
Although the class is criticized for its small displacement compared to their extensive equipment, the previous Audace class were even more cramped, being 900t lighter and with a bulky powerplant, yet armed the same after thier later upgrade, with an extra Super-Rapido gun (so four instead of three). Later after entering service in 1993 the new destroyers were criticized for their lack of vertical launchers (VDS), not purchased due to financial constraints, just modernizing their launchers to the Mark 13 for the SM-1 standard. Still comared to the later FREMM, the Durand de la Penne class were the last and most powerful “conventional missile destroyers” and also the costliest at 1,500 million lires for both these ships as per the 1981–1993 program. At the time they were completed the cold war was ended and so the two more planned back in 1987 were cancelled. This was a reason why Italy also sought after scale ecnonomics by making a rapprochement with France and UK for their next class.

Hull and general design

The hull is generally similar to the Audace, a continuous flush deck with a low and large stern for the helipad, and pointy clipper bow, with bulwarks. The superstructure consisted still of two blocks, relatively low and wide with a high antenna mast with triangular cross-section and all electronics included. The engines were exhausted in two groups, one for each superstructure. After they were exhausted flank to flank, slightly inclined and provided with thermal cooling system to reduce the IR signature. Behind were located the standard missile system and helicopter facilities which were roomier to enable the later use of larger models, such as the far more capable EH.101.

Powerplant

Despite the adoption of a CODAG system, they maintained a top speed of 32 knots when using the gas turbines, at the price of a large reduciton in range. This was still two knots less than the previous Audace class vessels, and in service, top speed was capped to 25 knots (46 km/h) to keep endurance. But overall, the compact design of this new powerplant enabled for extra internal space and fuel oil storage. The core is two General Electric LM-2500 gas turbines, made under licence by FIAT, quite successful and widespread naval turbines (used by 29 navies), and two diesels.
The latter are GMT BL-230.20-DVM made by Wärtsilä Italia S.p.A. These diesels are used for cruising and provides a top speed of 21 knots.
Both are linked with one shaft and a 5 blades propeller, which shape was studied to reduce noise. The entire propulsion is remotelly controlled, with an access only provided for specific maintenance and repairs. In daily operations, no personal was present inside. The surrounding walls and ceiling had extra fire-fighting systems and acoustic material around.
Using the siesels, the destroyers could erach 7 000 nm at 18 nodi (12,960 km at 33,34 km/h) but probably less than 1,000 nm with the Gas Turbines. The diesels enabled a range to criss-cross the Mediterranean and beyond.

Protection

The Durand de La Penne class were built to be much more difficult to sink than the previous Audace, a reflection of the Falkland war lessons. Many bulkheads and anti-fire systems were provided, all the main communication lines and computers were duplicated. There was also a fully operating NBC system for the crew completed with internal air conditioning system, overpresuren hatches and doors sealing, external detectors, and deck sprinklers for a complete washup.

Stealthiness made its apparition, with reduction of the RCS, better sloped structures, better integration of external elements into it, as well as some rafting for the machinery, made easier by the lighter and more compact units (so reducing noise), as well as reducing heat and magnetic signatures.
As for vulnerability and general characteristics, these ships, while still prestigious, were still smaller than was actually needed and so explosives concentration is still very high. In the foredeck over 20 meters are 3 medium caliber guns and over 200 shells sotred behind deck ready for use, the Aspide system and up to twenty four 230 kg missiles below deck as well. In the aft superstructure are concentrated a gun, 2 helicopters and forty SM-1/2 missiles amounting to 24 tonnes, and over one tonne of high-explosive warheads as well as ASW torpedo stores for Mk 46 or A244 torpedoes in less than 25 meters. Many of thse spaced received armour, as well as the well buried Central Operation Room. The crew complement fortunately was reduced to 380, thanks to autmomation, but still larger than as contemporary designs. However all these extra arms are seen as an advantage to control damage or fire.

Armament

These destroyers includes gun batteries scattered over all the ship, covering all angles (contrary to the Audace) and making for a profile well recognisable. The anti-aircraft equipment comprised no less than six weapon systems and probably the better of all branches to cover all ranges while using four different types: The Standard SM-1 launcher Mk13 covers the long range beyond 45 miles (72 km), the Albatross-Aspide missiles the short range up to 15 km, the main gun Compatto 127/54 (5 inches) up to 25 km, and the three Super-Rapido 76 mm 16-20 km. This suite is expecially strong on the forward quarter, a classic choice as it was easier to “point” the ship towards the main target when detected.

If the Standard missiles are dedicated to long range air defence, the rest is medium to short range and the Aspide are very similar to the Sea Sparrow, and very advanced, with monopulse guidance from 1977, but almost identical to Sea Sparrow, mass-produced by Alenia before them, a clear advantage when starting these new missiles. They were roughly roughly equal to Sparrow-M, with 16 missiles are in the magazines, an Riva-Calzoni system to quickly load 4 at once in the 8 cell launcher.
One Compatto 127 mm was removed from the Audace as Aspide was fitted and it was modernised and reused on the Durand de la Penne class. A dependable beast of burden capable of engaging ships and shore targets as well if needed.

The OTO Super Rapido are powerful for their calibre and yet heavier than CIWS but still can shoot up to 120 rpm. Thehir fuse explosing 6.3 kg (14 lb) shells are sophisticated to be sure to “kill” any incoming missile at at 6 km (4 mi), including sea-simming ones. OTO claimed they could can engage 4 missiles in succession in a single sector, per gun, provided they are of the subsonic type. They are judged much superior to the like Dardo 40 mm guns and eve, the 25 mm gatling CIWS despite its 10000 rpm capability. Four RTN-30 radar-optical system control these, two fore and two aft, so not all can shoot simultaneously at different targets.

To defend against other ships beyond the horizon and closer, the destroyers again have three layers: The anti-ship Otomat system ios proven, very long range at 180 km or more, and with mid-course guidance by AB-212s helicopters above the horizon iof needed. They are sea skimming models with a powerful 210 kg (463 lb) warhead. Eight ate placed in mid-ship canisters between the two main superstructures. At intermediate range, the Helicopters are still supposed to carry and fire missiles, and the close range is assured by the main gun.
When commissioned, these ships had the AB-212ASW helicopters (see later) later upgraded to the EH-101. They assured the bulk of ASW protection at long range, due to their capacity to carry buoys, VDS, and ASW torpedoes. This is completed at long range by Milas ASW missiles (installed later) and at shorter range by triple 324 mm torpedo launchers, always dependable.

Mk13 launcher, SM-1 Standard

Installed aft, single launcher, 40 in store.

Selenia Aspide SAM

Installed forward, octuple Albatross launcher with rapid reload, 24 reloads.

OTOMAT Mk2 SSMs

In two angled unarmoured canisters amidships, between islands facing port/starboard, no reload.

Milas ASUW

Entered service 2002, development started 1986 as Franco-Italian program. Based on the Otomat but larger, 6 m (20 ft) long, 800 kg (1,800 lb) carrying a MU90 torpedo to 35 kilometres (19 nmi).
Fitted in canisters, same as the otomat, placed amidships facing both sides. They did not replaced former Otomat SSMs. The canister are double (One OTomat Mark 2 aboce, one Milas below). More

Otobreda Compatto 127 mm gun

OTO Melara 76 mm Super Rapido

B15 TTs

Classic triple 324 mm torpedo tubes, USN Mark 46 types, built in Italy as the WASS B515/3. They are located close to the hangar on deck aft. Reloadable. Trainable surface vessel torpedo tubes (SVTT) very similar to the Mk.32 SVTT. Engineered by Whitehead Alenia Sistemi Subacquei, Livorno, part of Finmeccanica and now Leonardo, partner of EuroTorp. 324mm (12.75 inches) diameter, 3.40 meters long, acoustic. Compatible with the MU90/Impact LWT, A244/S LWT, and Mk.46 Torpedo.

Sensors

The electronic systems makes a complete suite between 11 different radar systems.
The most important is the SPS-40 tri-dimensional radar over one of the 2 triangular trees aft, US built and capable of 300 km (186 mi) range in S band. The other is a SPS-768 bi-dimensional model by Alenia, same range buy in D band placed over the turrion. There is a radar for low-flying aircraft/ships of 160 km (99 mi) range in S band, forward tree. It is linked with the Dardo Fire Control System. The forward tree also harbors small electronic antennas for communications, datalinks and ECMs.
The surface radar SPS-702 works in X band and using solid-state electronics. The navigation radar in the forward tree uses X band.
Six Fire Control Radar are used for at first, the two Standard missile radars as the AN/SPG-51 D working in G/I band. There is a FCS Mk 74 Mod.6. 4 DARDO-E for the artillery but also the Aspide SAM working in K-band add to a TV, IL as well as a laser and IR sensors.
The DE 1164/1167 sonar ofor ASW is using the immersion VDS DE 1167 element.
For active protection the ECM suite set Nettuno is used completed by two French rocket launchers DAGAIE replacing the Breda SCLAR systems and featuring 10 tubes, 330 mm (13 in) cal. all capable of 10 km (6 mi) range, to blind IR-radars. The combat system Alenia IPN-20 is central to operations and completed by the SADOC-2 computerised elaboration system to manage all tactical information and communications, with 10 consoles, one operator each, the same elevel as the carrier Giuseppe Garibaldi. This allows them to act as command ships if needed.

1 × SPS-52C 3D radar
1 × AESN MM/SPS-768 radar
1 × medium range AESN MM/SPS-774
1 × surface radar AMS MM/SPS-702
1 × navigation radar SMA MM/SPN-703
4 × AESN Orion RTN-30X (MM/SPG-76)
1 × sonar system DE-1164/1167
1 × TACAN URN-25
1 × SADOC-2 combat system

Active protection

The class Electronic warfare & decoyssuite comprises:
– ECM system Elettronica SLQ-732 NETTUNO
– 2 x SAGEM Sagaie decoy launching system
– ASW AN/SLQ-25 Nixie, Surface Ship Torpedo Defense (SSTD) System

Air Group

NH-90 in 2012
Double Hangar for 2 helicopters. These could be the AB-212 (by default) or NH90 and later in life the hangar was made more moduklar to accomodate a single EH101 heavy helicopter, also with reinforced deck and new guidance systems.
On 23 June 2011, the navy received its first NH90, delivered to an interim MOC standard for training and SAR, ASW/ASUW cap. retrofitted in FOC (Final Operational Capability) standard. In October 2023, the Italian Navy received its 56th and final NH90; that same month, the service also reportedly attained a cumulative 35,000 flights hours across its fleet. They did not formally replaced the AB 212s of the Durand de La Penne but were tried on board. Instead they are in service with Italian Frifgates, starting with the FREMM.
The NH 90 brings a top speed of 300 km/h (190 mph, 160 kn) for a range of 1,000 km (620 mi; 540 nmi) in NFH variant, 5 hours operation, with anti-submarine and/or air to surface missiles.

Luigi Durand de la Penne in Odessa with her NH90 on the helideck.

Conway’s profiles: Audace, top, Durand de la Penne, bottom for comparison