Sh89 'Sea Tiger' CIWS

[Found this lying around in unfinished draft form, having begun it a couple of weeks ago. Writeup is still a bit underdone, but I might leave it as it is.]




Sh89 'Sea Tiger' Close-In Weapons System - The Federation of Ekraysia

Statistics


Class: Close-In Weapons System

Height:
Above Deck: 3.50m
Complete System: 6.19m
Length: 7.15m
Weight: (Complete System) 11,513kg
Traverse 360°
Armament:
1x Sh89G2 37mm ETC Rotary Cannon, 2195 Rounds
13x Sh89M 'Felix' SRSAM Cells, 3+ Reloads Per Cell

Sh89G2 Rotary Cannon:
Calibre: 37x270mm
Feed: Left-Side Linkless Belt
Barrels: Seven
Elevation: -21° to +84°
Operation: Gas-Operated
Rate of Fire: 3950rpm
Weight: 560kg
Range: 5000m
Length: 6.3m
Barrel Length: 3.367m
Muzzle Velocity: 1050m/s

Sh89M 'Felix' Short-Range Surface-To-Air Missile:
Weight: 94kg
Length: 2.93m
Wingspan: 49.5cm
Diameter: 16.8cm
Warhead: 13kg Blast Fragmentation
Guidance: Initial Intertial Phase with Course Correction; Semi-Active Radar Homing or Passive Radar Homing/ESM or Infrared Homing
Speed: Mach 3.5
Range: 15.2km
Engine: Karmen Defence Aeronautics Kar-SR-345 Solid-Fuel


History


The Royal Ekraysian Navy was quick to take up the Close-In Weapons System concept, but had long failed to standardise one. Initially, with the advent of the Phalanx, the navy had experimented with a twin-mount OTEN Type 6 Revolver cannon using the ship's radars. This was followed by a mount in which six Sh220 25mm automatic cannon were mounted in two rows of three, and oddly enough, this was chosen over the former on survivability grounds, and had been in use for nigh on two years in a number of ships when it was finally realised the system was not suitable, for several very good reasons: (1), it was overly complicated, (2) it lacked the correct electronic equipment for it, and (3), had quite a few jamming problems on account of the multi-truncated feed, at elevations above twenty degrees. As such, the navy formally issued a requiem in November 1987 for a new system to be developed. There were two specifications originally issued; one was asking for a gun system of larger calibre, but the other wished to investigate the possibility of a missile system. The benifits of a missile system were numerous. For one thing, they were far more accurate and longer-ranged, and a new Close-In Weapons System (CIWS) mount utilising them would negate the need for short-range SAMs in naval Vertical Launch Systems, saving space for other missiles. Karmen Defence, along with MYS, set about designing a gun system, but Axon decided to be more adventurous and go down a middle road: a gun system with a smaller missile launcher on the same mount. The project was codenamed 'Sea Tiger', which was later adopted as the official name.

In the meantime, Karmen/MYS were running into financial troubles, and scrapped the project, the former deciding to join forces with Axon to help them fill the tender. Karmen procured the Sh89G Rotary Cannon for the gun element of the system, hence the suffix 'G', and a prototype was ready by 1989, after which ten pre-production models followed. The system was standardised as Sh89 prematurely, anticipating good trials, but these did not go well. The 25-cell launcher, with a gun mounted above, was having teething reliability effects on the gun, and the project was temporarily shelved until 1991, when a new government came in, as did new funding. After extensive modifications to electronics and layout of the general system, a new version of the 'Year Type 1989' was finally ready, in 1996. Among modifications was a new variant of the gun, the Sh89G2, with ETC technology and a lengthier case. The system is now standard-issue on most Ekraysian ships, and although some retain the six-gun Sh220 setup and will do into 2013, these are being supplemented.


Gun


The most visible element of the whole system is the Sh89G2 seven-barrel rotary cannon, 'Gatling Gun', chambered in the new, Ekraysian standard 37x270mm rimless, linkless cartridge. While the system was originally envisaged to use two or three 25mm OTEN Type 6 revolver cannon, a single, larger, faster-firing weapon was chosen on the grounds of simplicity and dimensions of the mount, and increased lethality, particularly when firing AHEAD (Advanced Hit Efficiency and Destruction) rounds, which now, in Ekraysian ships, constitutes around 90-95% of the ammunition carraige. The complete system carries 2,195 rounds of 37mm ammunition in total, including the below-decks magazine. That amount of ammunition is all in a continuous belt, unlike some CIWS systems, which need to be reloaded several times before completely expending their ammunition. The Sh89G2 is only reloaded when the below-deck magazine is completely empty. If the magazine is being accessed but the Sh89 is still loaded, it will continue to fire.

The cannon is gas-operated and can initially be spun up to speed by two compressed-gas charges on either side of the breech. Seven are carried in chutes. It was originally designed as a larger, gas-operated variant of the GAU-8/A 30mm Rotary Cannon, with an equivalent between-service life and rate of fire. Out of neccessity, the Rate of Fire has been slightly toned down from 4200rpm to 3950rpm. Despite possessing a chromed and fluted, heavy breech and barrel, the gun's barrels will only last for just over a minute at the maximum rate of fire. The weapon incorporates Plasma-Jet Electrothermal-Chemical technology, permitting a heavier weight of shell (840g, AHEAD), higher muzzle velocity and energy. The barrels are autofregatted and stress-hardened, with twelve-groove traditional rifling.

In actual usage against missiles, the gun is only fired by the computer system after detecting that missiles, which would be fired first, have failed to bring down the target, which can be surface targets as small as jetskis, shore targets, low-to-medium-altitude aircraft, as well as missiles. At ranges below 1000m, the gun would be fired in addition to a missile launch. Missiles are not restricted to firing at a target once, although they are programmed not to be fired at point-blank range (below 150m), at which point the gun is relied upon. The gun can elevate or depress at a rate of 105 degrees per second, combined with a traverse speed for the whole mount of 175 degrees per second.

Against targets that the radar cannot lock on to, or for most shore targets, the gun is currently incapable of remote operation in these circumstances, although this may be remedied in the next system upgrade. In such a situation, a fold-out side seat is provided on the right of the gun as well as power-operated controls and a large, illuminated ring-and-bead sight.


Missiles


The missile component of the 'Sea Tiger' is fired from two five-cell, vertically-stacked launchers either side of the gun, as well as a three-cell, horizontally-stacked launcher on top. The top launcher elevates with the gun and can independently elevate to forty degrees additionally, while the two side five-cell launchers elevate to plus fifty degrees maximum. The cells have to be reloaded manually, and three reloads per cell are stored in the magazines. Depending on the ship class, more reloads are often carried elsewhere.

The missile itself is the Sh89M 'Felix' hypersonic, short-range, surface-to-air missile, which spins around it's longitudinal axis, similarly to the RAM. Developed from weapons such as the Naval Crotale and RIM-116 RAM, with a similar overall size, it has a maximum speed of Mach 3.5 which is reached in 2.2 seconds optimally, and a range of just over fifteen kilometres, negating the need for an additional, general-purpose SRSAM system. It has an engagement altitude of between seven and eight kilometres, and has a 13kg blast-fragmentation warhead with an eight-metre kill zone. After the onboard radar (MMW) and/or ship's radar(s) - input from both are used although only one is required - detects a missile, it will determine if the missile is incoming or outgoing, whether it is hostile, and will try to match it to a database of known missiles. This information will determine the type of guidance it will use, after an inertial launch phase. There are three options, Semi-Active Radar Homing, Passive Radar Homing/ESM, or Infrared Homing. If either of the first two are used and they fail, they will automatically default to infrared homing.

Semi-Active Radar Homing is the default. The logic is simple: since the launch platform, originally intended to be a surface ship, would have a radar system which was capable of detecting, identifying as hostile and actively tracking the target, duplicating this on the missile is a weight-increasing, overly expensive waste of time. By using the aforementioned radar to guide the missile, the missile is made less prone to ECM, electronic countermeasures, jamming, and error in general due to failure of the electronics. In newer versions, there is an Imaging Infrared seeker on all versions. Additionally, the passive/ESM mode is particularly useful since most long-range anti-ship missiles use radar to home in on their targets.

The newer software allows the missile to engage some nearby surface targets in addition to aircraft, the IFF and cataloguing procedures for aircraft being similar to those used for missiles. The 'Felix' uses a solid-fuel rocket motor in conjunction with triangular folding fins, with tail-mounted all-moving control surfaces. In an emergency, the Felix missiles can, in theory, be fired as unguided rockets in the same way that the gun is manually fired, although this has never actually being done.


Electronics


In addition to the ship's radar input, the system has an onboard MMW (MilliMetre-Wave) radar mounted behind the gun. The ship's main systems are programmed to be able to use data from the Sea Tiger's radar and computers as well by use of a triple-redundancy reinforced optical cable. The radar is designed to confuse enemy Electronic CounterMeasures (ECM) and safeguard the guidance of the Sh89M missiles.

The computer system for the Sea Tiger, overseen at all times by a human operator (although they can leave the system on automatic if required), is capable of tracking up to sixty threats at once, and classifies them according to the threat level, queuing them for engagement by the system if it judges they need to be engaged. For instance, an incoming supersonic anti-ship cruise missile will be placed above an incoming subsonic medium anti-shipping missile (unless the subsonic missile is slated to strike first), which will in turn be placed above a similar missile at a constant distance travelling parallel, which will in turn be placed above a lightly-armed terrorist in a small, unsteady biplane with engine difficulties. A processor and software upgrade is planned at least once every fifteen years, the next currently in development scheduled for late 2010.


Variants


None.


Export


Standard Price: $36,500,000

Package includes eight magazines' worth of 37mm ammunition and twenty-four reloads per cell of Sh89M 'Felix' Missiles.

I'd like to know whether the missile is generally realistic in regard to speed and possibly range.

range and speed are doable, you might want to make it a bit heavier into the 90-100kg range especially if you are using both SARH and an IR sensor.

You also ought to take that quote about comparing SARH to beam riders out it doesn't really add anything as everyone knows how much fail beam riders possesed.

Big, fast, expensive gun.

I still like my EO beam-riders though...
Can. Not. Jam.
A great thing when considering how short these engagement-ranges are.

Up'd.

Anything in particular wrong with a big, fast, expensive gun?

Guns themselves aren't as effective as made out to be for CIWS. That's why combined Missile/Gun CIWS are a reality.

Effectively, you'll only be able to use your gun for less than a second (assuming supersonic missiles) before the missile is either destroyed, or has impacted your ship. Point Defense Missiles have a longer range, and faster speed. Guns are retained in order to provide just that much more protection.

Also, it's a matter of personal taste for this one, but you could well use AHEAD ammo for this.

I do.