Monday, May 18, 2015

United States - Ticonderoga-class

During the 1980s, the United States and the Soviet Union continued production and ultimately produced some of the most powerful surface warships that have ever put to sea. In the United States, the penultimate cruiser resulted from a 1973 plan for a vessel known as a strike cruiser. American naval officials envisioned a nuclear-powered vessel that shipped the latest targeting systems, defensive missiles, antiship missiles, and cruise missiles that could deliver nuclear warheads as well as conventional explosives. The latter two systems were deemed important. An antiship capability was believed to be necessary given that the Standard missile, although it could be fired at a surface target, was too small to cause significant damage to a surface warship, and cruise missiles were needed to offset those of the Soviets. The cost of such a ship, however, was deemed too high by Congress, and the plan was consequently cancelled.

Even so, the idea of a vessel equipped with the newest missile control system did not die with the abandoned strike cruiser. The AEGIS Combat System was designed to not only control and coordinate the defense of a ship command the defense of entire task forces through the use of complex computers. First tested in 1973, AEGIS relies on a powerful radar, AN/SPY-1, that can simultaneously conduct searches and track more than 100 targets. This data is fed to the command center of a ship (CIC), where a computer evaluates which targets pose the greatest threat to the ship or task force and uses the vessel's weapons accordingly to address the situation.

In order to make the best use of such a system, U. S. naval officials believed that a hull the size of a cruiser's was necessary. The result was the completion of the 27 ships of the Ticonderoga-class between 1983 and 1994. The Ticonderoga cruisers measure 563 feet by 55 feet and displace 9,600 tons when fully loaded. In order to save money, these vessels are fitted with gas turbine engines that provide a maximum speed of 30 knots. The key feature is the AEGIS system, housed in the superstructure. Radar panels are mounted on the sides of the superstructure and provide a 360-degree arc of coverage; sonar systems provide underwater coverage. The data from these sensors are fed into the command center, which houses massive computer screens on the walls that reveal images of the space surrounding the ship and all ships, submarines, and aircraft within it. This system is directly linked to the weapons of the vessel. The first five ships are equipped with a primary armament of two twinarmed launchers, one each being located fore and aft. Both possess magazines that hold 88 missiles of varying types. Normally each magazine stores 68 Standard SAMs and 20 ASROC missiles. In ships constructed after the first five, the twin-armed missile launchers have been replaced by a vertical launch system (VLS) located in the forward section. This system is comprised of 144 canisters built into the hull.

Besides being able to launch SAMs and ASROC missiles, the Ticonderoga-class is also equipped with cruise missiles capable of being fired at naval and land targets. This addition greatly enhances the offensive capability of U. S. cruisers through the deployment of SSM systems that are far better than the limited surface ability afforded by the Standard system, originally intended as a surface-to-air defense. The smaller of these two weapons is the Harpoon missile.

The naval version of this missile was first deployed in the early 1980s and resembles the French Exocet antiship missile. It is still a primary weapon of the United States Navy and was first deployed on the Virginia-class cruisers when they were retrofitted. A Harpoon weighs 1,385 pounds and is 15 feet long. It carries a 488-pound warhead at a speed approaching Mach 1 and has a maximum range of almost 70 miles. Like Exocet, its guidance system allows it to home in on a target while skimming the ocean surface before striking the hull of an enemy vessel and exploding within. In the first five Ticonderoga-class cruisers, these missiles are mounted in box launchers that each contain four missiles. In later vessels, the Harpoon is shipped in the vertical launch system (VLS).

A larger and more powerful weapon, the Tomahawk cruise missile was deployed in 1986 and is among the most powerful offensive missiles in the arsenal of the United States Navy. This weapon weighs 2,900 pounds, but can weigh 3,500 pounds if it is equipped with a booster rocket for greater distance. It measures 18 feet, 3 inches, but length increases to 20 feet, 6 inches when the booster is included. The Tomahawk can carry a 1,000-pound conventional warhead or a nuclear payload out to 1,000 miles. The guidance system is extremely complex and allows for control that is largely independent of the ship that fires it. This guidance includes a targeting computer equipped with the Terrain Contour Mapping System (TERCOM). This system uses the missile's radar to examine the topography ahead of it in order to match it to a three-dimensional map stored in the missile's computer memory. The computer can correct the course of the weapon based on variations between the two maps. The Tomahawk is also equipped with Global Positioning System (GPS), which improves the reliability of the targeting data. Tomahawks also use Digital Scene Matching Area Correlation (DSMAC) during the final stages of flight. As the missile nears its target, DSMAC uses a camera to take a picture of the target, which the computer verifies. This equipment provides for great accuracy. The missile is extremely difficult to detect as it flies at a low altitude.

The Ticonderoga-class cruisers ship others weapons that augment missile capacity. Other than ASROC missiles, these ships carry two torpedo launchers that fire homing torpedoes, as well as two helicopters for use against submarines and surface vessels. They also carry two 5-inch fully automated guns in single mounts. One each is located in the forward and rear section of the ship. Finally, these vessels carry two Vulcan Phalanx Cannons for short-range defense. This technological innovation was ready for service in 1977 and is still in use in the United States Navy. This weapon is a 20mm Gatling gun that is fed by a magazine that holds 1,000 rounds. It was designed as a last measure of defense to destroy incoming missiles at close range, but it can also be used against aircraft. The gun can fire 100 rounds per second. It's computer-controlled tracking system is built into the gun mount and can direct effective fire to a range of 500 to 1,500 yards.

The Vulcan Phalanx is viewed as a successful defense weapon, but the defensive measures on board the Ticonderoga-class vessels extend past the weapons systems to the inclusion of armor. This feature had been discarded in U. S. cruisers since the construction of Long Beach, but advances in technology have allowed its return as the lightweight, extremely strong material known as Kevlar. Although this armor, mounted primarily on the sides of the hull, cannot completely negate the destructive effects of larger missiles, it can localize the effects of a blast and thus decrease the damage caused by a hit.

These cruisers, in light of the computer systems, weapons, and armor, are certainly among the most powerful warships ever built.

 AEGIS ships have a more effective radar at their disposal, however: the AN/SPY-1B/D/E passive phased array S-band radar can be seen as the hexagonal plates mounted on the ship’s superstructure. SPY-1 has a slightly shorter horizon than the SPS-49, and can be susceptible to land and wave clutter, but is used to search and track over large areas. It can search for and track over 200 targets, providing mid-course guidance that can bring air defense missiles closer to their targets. Some versions can even provide ballistic missile defense tracking, after appropriate modifications to their back-end electronics and radar software.

The 3rd component is the AN/SPG-62 X-band radar “illuminators,” which designate targets for final intercept by air defense missiles; DDG-51 destroyers have 3, and CG-47 cruisers have 4. During saturation attacks, the AEGIS combat system must time-share the illuminators, engaging them only for final intercept and then switching to another target.

In an era of supersonic anti-ship missiles that use final-stage maneuvering to confuse defenses, and can be programmed to arrive simultaneously, this approach is not ideal.

The US Navy’s Dual-Band Radar relies on products from 2 different manufacturers, but they’re integrated in a different way. They also use a different base technology. The use of active-array, digital beamforming radar technology will help DBR-equipped ships survive saturation attacks. Their most salient feature is the ability to allocate groups of emitters within their thousands of individual modules to perform specific tasks, in order to track and guide against tens of incoming missiles simultaneously. Active array radars also feature better reliability than mechanically-scanned radars, and recent experiments suggest that they could have uses as very high-power electronic jammers, and/or high-bandwidth secure communications relays.

Many modern European air defense ships, from the British Type 45 destroyers, to the Franco-Italian Horizon destroyers and FREMM frigates, to Dutch/German F124 frigates, use active array search and targeting radars.

Raytheon’s X-band, active-array SPY-3 Multi-Function Radar (MFR) offers superior medium to high altitude performance over other radar bands, and its pencil beams give it an excellent ability to focus in on targets. SPY-3 will be the primary DBR radar used for missile engagements. Many anti-ballistic missile radars are X-band, and the SPY-3 could also be adapted for that role with the same kinds of software/hardware investments and upgrades that some of the fleet’s S-band, passive phased array SPY-1s have received.

On surface combatants, the AN/SPY-3 would also replace the X-band AN/SPQ-9 surface detection and tracking radar that is used to guide naval gunfire, and even track the periscopes of surfacing submarines. On carriers, it would take over functions formerly handled by AN/SPN-41 and AN/SPN-46 PALS air traffic radars, and would work in conjunction with the new GPS-derived Joint Precision Approach Landing System (JPALS).

Lockheed Martin’s Volume Search Radar (VSR) is an S-band active array antenna, rather than the SPY-1’s S-band passive phased array. The Navy was originally going to use the L-band/D-band for the DBR’s second radar, but Lockheed Martin had been doing research on an active array S-band Advanced Radar (SBAR) that could potentially replace SPY-1 radars on existing AEGIS ships. A demonstrator began operating in Moorestown, NJ in 2003. That same year, its performance convinced the Navy to switch to S-band, and to make Lockheed Martin the DBR subcontractor for the volume search radar (VSR) antenna. It also convinced Lockheed Martin to continue work on the project as a complete, integrated radar, now known as “S4R”.

S-band offers superior performance in high-moisture clutter conditions like rain or fog, and is excellent for scanning and tracking within a very large volume. While Lockheed Martin makes the VSR antenna, the dual-band approach means that Raytheon is responsible for the radars’ common back-end electronics and software.

The VSR/S4R’s nearest competitor would be Thales’ SMART-L, an active array L-band/D-band radar that equips a number of European air defense ships, and South Korea’s Dokdo Class LHDs. Unlike the DBR, however, the ships carrying it use the conventional approach of completely separate radar systems, integrated by the ship’s combat system.

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