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| Otobreda 76mm | |
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The Otobreda 76mm Super Rapid as mounted in a stealth cupola (to reduce Radar cross-section) onboard the Norwegian Fridtjof Nansen. |
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| Type | Naval gun |
| Place of origin | |
| Service history | |
| In service | 1964 - present |
| Used by | See users |
| Production history | |
| Designer | Oto Melara |
| Designed | Compact: 1963 Super Rapid: 1985 |
| Manufacturer | Oto Melara (1963–2001) OtoBreda (2001 onwards) |
| Produced | Compact: 1964 Super Rapid: 1988 |
| Variants | See variants |
| Specifications | |
| Weight | Empty: 7.5 tonnes (17,000 lb) |
| Barrel length | 62 caliber: 4,724.4 mm (186.00 in) |
| Crew | remote controlled |
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| Shell | 76×900mmR (complete round) 12.34 kilograms (27.2 lb) |
| Caliber | 76.2 mm (3.00 in) |
| Elevation | -15°/+85° speed:35°/s (acceleration: 72°/s²) |
| Traverse | 360° speed: 60°/s (acceleration: 72°/s²) |
| Rate of fire | Compact: 85 rounds/min Super Rapid: 120 rounds/min |
| Muzzle velocity | 925 m/s (3,030 ft/s) |
| Maximum range | HE round fired at 45°: Compact: 20,000 m (22,000 yd) Super Rapid: 30,000 m (33,000 yd) |
| Feed system | Magazine capacity: 80 ready rounds on Compact gun mount 85 ready rounds on Super Rapid gun mount |
The Otobreda 76 mm gun is a naval artillery piece built by the Italian defence conglomerate Otobreda. It is based on the Oto Melara 76mm/L62 Allargato, which was bigger and heavier. A vehicle-mounted version known as the Otomatic was built for the self-propelled anti-aircraft gun role but was not put into production.
Unlike the older Allargato the Otobreda 76mm Compatto cannon system is compact enough to be installed on relatively small warships, like corvettes, avisos (a vessel somewhere between a corvette and a patrol boat), or patrol boats. The gun's high rate of fire makes it suitable for short-range anti-missile point defence, and its calibre also allows it to function in anti-aircraft, anti-surface, and ground support roles. Specialised ammunition is available for armour piercing, incendiary, and directed fragmentation, and a new stealth cupola has been designed in recent years.
The Otobreda 76mm has been widely exported and is in use with 53 navies. It has recently been favoured over the French 100mm naval gun for the joint French/Italian Horizon CNGF frigate project. On 27 September 2006 Iran announced it has started mass production of a marine artillery gun, named the Fajr-27, which is a reverse-engineered Oto Melara 76 mm gun.[1]
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Also called the "Super Rapido" this weapon, developed in early '80s, is the most up to date development of the Italian 76mm naval cannons, with an increased rate of fire of 120 rounds per minute. To achieve the higher rate of fire the Super Rapido requires a specially developed round that can be uploaded and chambered at higher speeds. While the older 76mm Allargato and 76mm Compacto can fire the new special round, it does not increase their rate of fire. Only the Super Rapido can fire at 120 rounds per minute. That rate is only done in short bursts, despite the water cooling of the barrel. The Super Rapido also improved on the serious vibration problems that the older Oto Malera and Otobreda 76mm mounts had that effected accuracy against smaller high speed air targets, for example anti-shipping missiles and guided bombs.
Despite their effectiveness, the Italian navy preferred the Super Rapido to the Dardo 40mm guns. The latter had a longer range when compared to other CIWS (being also the only one with proximity fuses ammunition), but the Italian navy wanted a longer range weapon. The 'Audace migliorata' class (De la Penne) was initially meant with four 40mm dual turrets, but this was shifted to three 76mm SR turrets. Breda tried with the Fast Forty 40mm, with increased rate of fire and even the possibility to use APFSDS ammunitions, but the Italian navy chose the SR gun, that was claimed as capable to manage several subsonic missiles from 6,000 to 1,000 meters away. This favoured the bigger weapon and the high costs of modern anti-missile ammunitions, as the long range helped to destroy missiles from greater distances, so one single gun can engage more than one missile in a single engagement, avoiding the danger posed by fragments and splinters when a missile exploded too close. The 76mm was also capable to be used versus surface targets being a medium calibre gun with relatively long range[2].
Following the development of OTOMATIC gun, there was a new naval 76/62, much more compact compared to the previous SR and Compatto. This was capable to hold 50 rounds in the ready ammunition magazine, but this new version was entirely 'above the deck'. This allowed much better disposition in the ships, just like the Phalanx CIWS. The Compatto and Super Rapido needed an ammunition well under the deck, to host the ready ammunition depots, so they cannot be hosted everywhere in the ship. This is why Durand de la Penne ships had three of them, as it was impossible to install one, as example, over the command tower, with the same field of fire of the two forward SR guns[3]. The 'Sovraponte' was also lighter, even if with a smaller ammo depot. It was not particularly successful, atleast not in italian navy.
In order to develop the maximum potential from those guns, OTO has also developed and is developing a complete family of ammunitions[4]:
There were evolutions in the fire control systems as well. The early versions (Compatto) usually used radars such the RTN-10X Orion (made by Selenia); from the early '80s there was a more powerful and flexible system, the RTN-30X (used with the Dardo-E CIWS system and known within Italian Navy as SPG-73), that was capable to manage both guns (40,76 and 127mm calibres) and missiles (Sea Sparrow-Aspide). With the Italian navy's this system came in service with the cruiser Garibaldi (C551: the RTN-30X entered in service first with Maestrale class frigate, but the Dardo 40mm turret were slaved to the smaller and older RTN-20X radars), but still with the twin 40mm Dardo's turrets; while the first ship equipped with Dardo E and 76mm Super Rapido was the upgraded 'Audace class destroyers', later followed by 'De la Penne' class.
There were many developments also in the fuses, especially in order to shoot down low-flying missiles. After some failed research (included the Kodak IR fuse) and with several problems of reliability (in early '90s it was discovered that the reliability of 40mm ammunitions dropped from the theoretical 90% to only 25% after only 5 years since their production by Borletti; the original Bofors ammunition did not have that problem and were sent to the italian cruisers 'Veneto' and 'Garibaldi' as they were high value assets)[6]. The best fuse developed with the SR guns was the 3A (programmable), produced since several years (arguably early 2000s).
Since the '80s, there were as well some studies in order to realize a guided 76mm ammunition, but this was not archivied until recently. The first kind of those ammunitions was the CCS (Course Corrected Shell), also known as 'CORRETTO', with a joint program OTO/British Aerospace[7]. The work started in 1985. This projectile had several small rockets in order to deviate the trajectory. The radio command was sent from the ship FCS, that did not knew the exact position of the projectile, but only those of the target. But this system was too complex and unreliable. So OTO studied another development in order to obtain a real 'guided ammunition'.
This development is called DART (Driven Ammunition Reduced Time of flight), hyper-velocity sub-calibre ammunition included in the DAVIDE system. This latter is also known with the commercial name of 'Strales' (latin term for 'Arrow')[8].
The DART projectile is similar, for many ways, in aspect to other hyper-velocity systems like the Starstreak SAM missile's dart, but this is a guided gun projectile with radio controls and a proximity fuse for low level engagements (up to 2 meters over the sea). DART is a small device (around 40mm calibre), fired at 1,200m/sec (4,000ft/second), capable to reach 5km in only 5 seconds, and pull up to 20-25g manoeuvres. The DART projectile is made of two parts: the forward is free to rotate and has two small canard wings for flight control. The aft part has the 2.5kg warhead (with tungsten cubes and the 3A millimetric wave new fuse), six fixed wings and the radio receivers[9].
The guidance system is Command Line of Sight (CLOS). It has a new RTN-25X radar, that controls both the target and the projectiles. The radio-command for them is provided with a broadcast data-link (Ka Band)[10].
The more recent development was the VULCANO ammunition system, that basically is a scaled down version of the 127-155mm Vulcano family of extended-range projectiles developed by OTO Melara. This is not a defensive, but an offensive weapon, capable to reach distances of at least two times greater than the usual 76mm gun ammunition thanks to the guidance system (INS and GPS) and the small wings[11] .
Platforms using the Oto-Melara 76 mm include:
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