Class frigate - La Fayette

The La Fayette class units (FL-3000 for "Frégate Légère de 3,000 tonnes", "3,000-tonnes light frigates", or "FLF" or Frégate Légère Furtive", "Light Stealth Frigate") are light multi-mission frigates built by DCN and operated by French Marine Nationale. Derivatives of the type are in service in Saudi Arabia (Royal Saudi Navy), Singapore (Republic of Singapore Navy) and Taiwan (Republic of China Navy).
These frigates were referred to as "stealth" frigates. Their reduced radar cross section is achieved by a very clean superstructure compared to conventional designs, angled sides and radar absorbent material, a composite material of wood and glass fiber as hard as steel, light, and resistant to fire. Most modern fighting ships built around the world since the introduction of the La Fayette have followed the same principles of stealth.
All information gathered by the onboard sensors is managed by the Information Processing System, the electronic brain of the operation centre of the ship. It is completed by an electronic command aid system.
The La Fayette has space available for the future installation of the Aster 15 air-defence missile, however they will not be installed due to recent cost issues. The ships are designed to accommodate a 10 tonne helicopter in the Panther or NH90 range (though they are also capable of operating the Super Frelon and similar heavy helicopters). These helicopters can carry anti-ship AM39 or AS15 missiles, and can be launched during sea state 5 or 6 due to the Samahé helicopter handling system. France ordered five ships of the La Fayette class in 1988, the last of which entered service in 2002.

Background

n the late 1980s, the Marine Nationale started the studies for frigates adapted to low-intensity conflicts in the post–Cold War era. The ships were to serve in the large French EEZ , be adapted to humanitarian operations or low-intensity operations in support of land troops, and replace the aging A69 avisos, which tended to prove too focused on naval operations and were ill-suited for joint operations. Conventional warships used in low-intensity or humanitarian relief operations proved costly, with their heavy equipment and large crew. Hence came the requirement for lightly armed frigates with economical engines and small crew. In Italy, the same requirements led to the development of the Cassiopea and Minerva type corvettes, built according to both civilian and military standards. These ships were limited to 1300 tonnes because the limited size and depth of the Mediterranean and the proximity of the homeland. The French Navy, on the other hand, had to be present in overseas territories, bases and EEZ. To be enduring enough, the ships had to reach 3000 tonnes, the size of a missile frigate. The larger displacement allows combining strong firepower (like the Minerva class) and a capacity for a medium helicopter (like the Cassiopea), along with a good autonomy and seaworthiness.
The first type of ships built on these principles were the Floréal class frigates, built on civilian standards, with a limited armament, and carrying a medium helicopter. These ships are high endurance units designed to be operated in overseas possessions (Caribbean, Polynesia and New Caledonia) and the EEZ, where the likelihood of a naval threat is low. The speed is limited to 20 knots because of the low power engine which emphasises autonomy and reliability. To fight pirates in fast rigid-hulled inflatable boats, the Floréals rely on their onboard helicopter and naval fusilier company.
The niche for more hostile environments is covered by the La Fayette type, designed to operate in complex zones like the Indian Ocean or Djibouti. These ships were to be able to secure the EEZ, but also to operate in naval groups or intelligence gathering missions. The intended role for the ships was in fact very varied, because the experience of the C.70 class, with an intended 20 ship cut down to only 9 (the 7 Georges Leygues class frigate and 2 Cassard class frigates) had taught that project downsizing and reorganisations could lead to badly balanced naval capabilities. The new ships were to benefit from breakthrough on stealth ("furtivité") achieved by the DCN in the 1980s.
It took several years to materialise the concept, and the first ship was eventually launched in 1992, two years after the final design was completed. The weapon system testing took place in 1994, and particularly extensive trials were undertaken to prove the structure of the ship under a wide range of conditions. The La Fayette was eventually commissioned in March 1996.

Stealth

At the time of their commissioning, the units of the La Fayette class were the state of the art in stealth for warships. The shape of the hull and the superstructures is devised for the optimal reduction of the radar signature, which has been reduced by 60%: a 3000-tonne La Fayette unit has the typical radar signature of a 1200 tonne ship. Stealth is achieved with inclined flanks, as few vertical lines as possible, and very clean lines and superstructures: stairs and mooring equipment are internal, and prominent structures are covered by clear surfaces. The superstructures are built using radar-absorbent synthetic materials.
The radar cross section is equivalent to that of a large fishing boat, which can make camouflage amidst civilian ships possible; or that of a much less capable corvette, which could lead an enemy to underestimate the capabilities of the ship. In case of a direct attack, the small radar signature helps evade enemy missiles and fire control systems. The La Fayette are also equipped with jammers that can generate false radar images, as well as decoy launchers. Further point missile defence will be provided when the ships are equipped with the Aster 15 anti-missile missiles.

Thanks to the adoption of low-power diesel motors and a special heat dissipation system, the La Fayette ships have a low thermal signature. The usual funnel is replaced with a small sets of pipes, aft of the mast, which cool the exit gas before it is released. The ships usually operate in warm areas, which further decreases the thermal contrast with the environment.
The magnetic signature is reduced by the presence of a demagnetisation belt.
The acoustic signature is minimized by mounting the engines on elastic supports, as to transmit as little vibrations to the hull as possible, and by rubber coating on the propellers. The La Fayette are equipped with the Prairie Masker active acoustic camouflage system, which generate small bubbles from underneath the hull to confuse sonars.

Construction

The superstructure is made of light alloy and glass-reinforced plastic, which allow a reduction in top weight. This provides adequate but sub-optimal resistance to fire. Vital zones are armoured in Kevlar , and important systems are redundant. The crew is protected against biological, chemical and nuclear environments.
The ships were built with a modular inner structure from 11 prefabricated modules which were completed at the factory, delivered to the shipyard and assembled there. This technique results in a construction time of less than 2 years.
The hull has a pronounced angle at the stem, with a short forecastle that integrates directly into the superstructure. The ship's sides have a negative inclination of 10 degrees. The single anchor is located exactly on the stem, into which it is completely recessed. The deck where the seamanship equipment and capstans are installed is internal in order to hide it from radar.
The superstructure is built in one piece and directly integrates into the hull, with only a change in inclination. A platform is located between the main gun and the bridge. The superstructure runs continuously down to the helicopter hangar, on top of which short-range anti-air Crotale missiles are installed.
The ships feature two masts. The main mast has a pyramidal structure which integrates funnels and supports the antenna of the Syracuse military communications satellite system, while the second supports the main radar.