The naval field of operations is divided into three distinct areas of action, undersea, surface and air. And any modern major surface unit must be able to cope with claims in all three domains, conducting defensive and offensive missions.
As a consequence of the above, it is crucial to choose the right mix in the composition of armament that the vessel will carry, always together with the cost parameter. Of course, the naval custom, i.e. the habit of using specific weapons, should not be overlooked. Therefore, in the category of “custom” we could include the most basic category of naval weapons, the naval guns which are distinguished by the following advantages:
- Low cost of acquisition compared to missile systems
- Great variety and supply of ammo
- Performance in surface and air warfare
Excluding the disagreements of the past by the French and British Navy, with their 100 thousand guns. and 113 thousand respectively, and the failure of the Americans to develop a satisfactory gun at 155 mm, at the level of western navies the lion’s share is claimed by the medium gun of 76 mm and the heavy gun of 127 mm, with the main ambassadors being the products of the companies Leonardo and BAE Systems.
Nevertheless, in recent years the 57mm caliber has gained momentum with its main representative being the Bofors 57 Mod3 gun, and its American variant Mk110 Mod0 with a low-observability turret. The weapon, which derives its origin from the anti-aircraft Bofors 40/L70, evolves the philosophy of a light gun, with the main characteristics of low weight, low service and maintenance requirements and high speed. The gun in this modern version has a small radar above the barrel to measure the exit speed of the projectile, for improved fire control.
Thus, the tower weighs only 6.8 tons empty in the American version and 14 tons with all 1,000 shells, with 120 of them ready to fire, while the firing rate reaches 220 rounds per minute. It can also be serviced for loading with just 3 people compared to twice as many for a 76-man, while it has lower maintenance requirements.
The gun is produced in two versions, the basic one which requires deck drilling and has a longer feed and the compact, without drilling, with the ammunition placed in special magazines and feed being done manually through a rear access port.
As a calibre, on a global scale it is quite widespread, with 17 countries having chosen it at times (in various versions), both for Torpeoded Surface Vessels and corvettes, as well as for frigates. E.g. it is the main cannon for the Swedish Visby corvettes, the Malaysian Gowind, the British Type 31 frigates, for the American LCS, for the also American Constellation frigates, etc.
57mm or 76mm?
A reasonable question is whether these features are enough to make someone choose a 57 mm gun over the classic, reliable and widely used 76. Obviously, it comes down to the needs of each user.
But the main reason for choosing the gun by the US Navy is interesting. Therefore, according to the tests they carried out, it was found that the significantly higher velocity of the MK110 allows for a greater transfer of explosive material or number of fragments on the target, compared to the 76mm standard. at this time, that is 76/62 SR, so the destructive power is higher. Of course, the ammunition used also plays a big role in this, and this is where the virtues of the system can be seen.
57 mm ammunition
Since 2006, the standard choice of users has been the ammunition Mk295 Mod0 3P-HE, more simply 3P, from BAE Systems, with a range of 17 kilometers. The missile’s fuze has six programming options, selected milliseconds before the missile is fired, as it constantly receives data from the ship’s fire control system, depending on the threat. The 3P has an AirBurst function, during which it releases over 8,000 Tungsten fragments, covering an area of four hundred square meters.
An evolution of the 3P, it is the guided munition Mk295 Mod1 or otherwise ORKA, also of BAE. ORKA is designed in the logic of “one shot, one kill” and for this reason it uses a semi-active Laser (SAL) dual imaging searcher. This practically means that the projectile can be directed towards the target either through pointing from a Laser source, or autonomously through the correlation of the image of the target with the database that is loaded into the projectile before firing. The ORKA’s steering, provided by four folding vanes, has the same firing tube functions as the simple 3P, but has a shorter range of 10 km.
In the development dance of advanced ammunition for the 57 mm guns. the American company L3Harris entered as well, with the also directed Mk332 Mod0 ALaMO (Advanced Low-Cost Munitions Ordnance). Although not much information is available on the projectile, the ALaMO is designed to detonate within the target rather than at a distance from it. To achieve this, it uses a radio frequency (RF) seeker, and after detection is achieved, the required advance maneuvers follow to engage the threat. The missile is already in use by the US Coast Guard and Navy.
MAD-FIRES, when DARPA innovates
But why should the US Defense Advanced Research Projects Agency (DARPA) deal with the “humble” ammunition of 57 thousand? From what little information is available (after the testing and manufacturing of the MAD-FIRES program was outsourced to Raytheon), the new missile he designed is taking a serious evolutionary step.
Thus the MAD-FIRES (Multi-Azimuth Defense Fast Intercept Round Engagement System), was designed to be able to engage all anti-ship missile threats, especially the new multisonic designs.
The missile has a rocket motor for greater range and speed, while the seeker, probably with fire and forget technology, will be able to detect the targets. The most impressive feature of MAD-FIRES is that it will be able to re-engage targets that survived the first engagement. Obviously, the cost of such a missile will be significantly increased, but it will likely remain a fraction of conventional anti-missile systems, such as the RAM missile, which now costs over a million dollars. Also, in a hypothetical scenario of countering hypersonic missiles, in the short window of time given for defense, with 10-15 seconds available to react, a velocity of 220 missiles per minute allows dozens of missiles to be fired, even against multiple targets.
The somewhat paradoxical choice of a medium to small caliber gun as a primary weapon system, even on large modern naval units such as the British T31s and US Navy Constellations, can therefore be understood. While the low weight of the turret allows its application also on a boat, e.g. of 150 tons, to acquire anti-missile capability as well.
So this caliber can also stand next to the more traditional ones, which also maintain their own advantages: such as the excellent range e.g. a 127mm and with “heavy” filling for land attack, or even better as a Vulcano for high accuracy, or the versatility of choosing an efficient all-purpose 76mm, offered in a single version, but also as a multi feed using different types of ammunition, or even as STRALES with its own tracking and targeting radar.
