OTO Melara 76 mm

Otobreda 76 mm
Otobreda 76 mm
	The Otobreda 76mm Super Rapid as mounted in a stealth cupola (to reduce Radar cross-section) onboard the Norwegian Fridtjof Nansen.
Type	Naval gun
Place of origin	Italy
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
Mass	Empty: 7.5 tonnes (17,000 lb)
Barrel length	62 caliber: 4,724.4 mm (186.00 in)
Crew	remote controlled
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 round/min; Super Rapid: 120 round/min
Muzzle velocity	925 m/s (3,030 ft/s)
Maximum firing 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 100 mm 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]

Other specifications

Cooling: sea water—fresh water for flushing
Electrical Power supply
- 440 V, 3-phase, 60 Hz, main circuit;
- 115 V, 1-phase, 400 Hz, servo and synchro network

Variants

Super Rapid

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, italian navy preferred the Super Rapido to the Dardo 40 mm turrets. This latter was already a long range when compared to the other CIWS (being also the only one with proxy fuses ammunitions), but italian navy wanted a longer range weapon. The 'Audace migliorata' class (De la Penne) was initially meant with four 40 mm dual turrets, but this was shifted to three 76 mm SR turrets. Breda tried with the Fast Forty 40 mm, with increased rate of fire and even the possibility to use APFSDS ammunitions, but italian navy choose neverthless the SR gun, that was claimed as capable to manage several subsonic missiles from 6,000 to 1,000 meters away. This compensed 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 76 mm was also capable to be used versus surface targets being a medium caliber gun with relatively long range^[2].

Sovraponte

Following the development of OTOMATIC gun, there was a new naval 76/62 mm, much compact compared to the previous SR and Compatto. This was capable to hold 50 rounds in the ready ammunition depot, 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.

Ammunitions and the new DAVIDE system

In order to develop the maximum potential from those guns, OTO has also developed and is developing a complete family of ammunitions^[4]:

HE standard (all models): weight 6.296 kg (750 gr HE), range 18,4 km at 45°, effective 8 km (4 km vs. air targets at 85°)
MOM: developed by OTO (Multirole OTO Munition), but this model was dropped after the comparation with the PFF made by BPD.
PFF: anti-missile projectile, with proximity fuse and 0.5 grams tungsten cubes
SAPOM: 6.35 kg (0.46 kg HE), range 16 km (SAPOMER: 20 km)
DART: 4 kg (0.4 kg HE), effective range 5 km+
Vulcano: 5 kg, maximum range around 40 km (it is a smaller version of the 127 mm Vulcano)^[5]

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 127 mm) 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 40 mm turret were slaved to the smaller and older RTN-20X radars), but still with the twin 40 mm Dardo's turrets; while the first ship equipped with Dardo E and 76 mm 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 shot down low-flying missiles. After some failed researchs (included the Kodak IR fuse) and with several problems of reliability (in early '90s was discovered that the reliability of 40 mm ammunitions dropped from the theoric 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 '00s).

Since '80s there were as well some studies in order to realize a guided 76 mm 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 devopment is called DART (Driven Ammunition Reduced Time of flight), iper-velocity de-calibred 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 hypervelocity 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 40 mm caliber), fired at 1,200 m/sec (4,000 ft/second), capable to reach 5 km in only 5 seconds, and pull up to 20-25 g manouvers. 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 2,5 kg 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 127-155 mm Vulcano family of extended-range projectiles developed by OTO Melara. This is not a defensive, but an offensive weapon, capable to reach distances atleast two times greater than the usual 76 mm gun ammunition thanks to the guidance system (INS and GPS) and the small wings^[11] .

Other specifications

Variants

Super Rapid

Sovraponte

Ammunitions and the new DAVIDE system

Users

Asia

Africa

Europe

North America

Oceania

South America

See also

References

External links