Redoutable-class submarine (1967)

The Le Redoutable-class submarine was a ballistic missile submarine class of the French Navy (Marine Nationale). In French, the type is called Sous-marin Nucléaire Lanceur d'Engins (SNLE), literally "Missile-launching nuclear submarine". When commissioned, they constituted the strategic part of the naval component of the French nuclear triad, then called Force de frappe (the aircraft carriers FRENCH AIRCRAFT CARRIER Clemenceau and FRENCH AIRCRAFT CARRIER Foch constituting the tactical part).

The class entered active service in 1971 with FRENCH SUBMARINE Redoutable, six submarines were built in total. All have since been decommissioned. The structural changes in Inflexible have seen it regarded as a different class from the early boats. The class has been superseded by the Triomphant-class submarine.

Background
With the election of Charles de Gaulle as president of France, the French Armed Forces saw a change in direction. Under the new government, French forces were withdrawn from NATO formations due to French unhappiness with American domination of the group. Beginning in the 1960s, French foreign policy would be reshaped to create independence from both of the major opponents of the Cold War, the United States and the Soviet Union. This was later defined in the mantra "to deter – to intervene – to defend". From the foreign policy arose the concept of submarine-based "Force de Dissuassion", with emphasis on the "to deter", which was the focus of new French naval spending.

The new nuclear-powered, nuclear-armed submarine force was planned to be of similar size to the British Royal Navy. However, unlike the British, the French received no support from other nations and the French nuclear program began with a lack of technological expertise to draw from. Furthermore, the Americans refused to provide the French Navy with enriched uranium for the creation of a nuclear reactor. Nevertheless, the project was authorized in 1963. The French Navy resorted to working in conjunction with the civil French Alternative Energies and Atomic Energy Commission (French: Commissariat à l'énergie atomique et aux énergies alternatives), which the US allowed to acquire enriched uranium for experimental land use. A nuclear plant was constructed on land at Cadarache and the reactor was tested to simulate nuclear-powered submarine patrols. Other developments made by the groups working on the project include the development of high-tensile steel by France and the adaption of the submarine hull to nuclear propulsion.

At the same time as the French were developing nuclear propulsion, they were also researching ballistic missiles and nuclear warheads. Caissons were constructed to test fire missiles and by 1967, the submarine FRENCH SUBMARINE Gymnote was fitted with the guidance and navigation systems to be tested. The first ballistic missile launch was at the Landes Trials Centre (French: Centre d'Essais des Landes) at the end of 1968 and nuclear warheads were tested at Moruroa in the Pacific Ocean.

Description
Designated Sous-marin Nucléaire Lanceur d'Engins (SNLE) literally "Missile-launching nuclear submarine", the design initially measured 128 m long overall with a beam of 10.6 m and a draught of 10 m. The submarines initially displaced 7500 t surfaced and 9000 t submerged. This later increased to 8000 t surfaced. The submarines were powered by one pressurised water reactor providing steam to two turbines and two alternators and turning one propeller via a turbo reduction drive creating 16200 hp. The submarines also sported electric emergency propulsion capable of providing a range of 5000 nmi. The vessels could dive more than 200 m and had a maximum speed of 20 kn. Each boat had two twin crews comprising 15 officers and 120 men.

Armament
The Redoutable class all have 16 compartments for submarine-launched ballistic missiles. Redoutable initially deployed with 16 the M1 MSBS (Mer-Sol Balistique Stratégique). The M1 missile was a two stage ballistic missile with a 10.4 m height and each missile weighed 18000 kg. The M1 had a 400-kiloton warhead and an approximate 2500 km range. Terrible was also constructed to carry this missile. The design of Foudroyant was altered to carry the improved M2 MSBS missile in 1974. The M2 was heavier at 19800 kg, had a 500-kiloton warhead and a longer range than the M1. In 1977, both the M1 and M2 were replaced by the M20 MSBS.

Service history
The first submarine, Redoutable, was ordered in 1963, built at Cherbourg, launched in 1967 and commissioned in 1971. This was replaced by the M2 MSBS beginning in 1974, which was in turn replaced by the M20 MSBS beginning in 1977. All except Redoutable were heavily upgraded from 1985 to fire the second generation MIRV capable M4 missile – Tonnant was recommissioned in 1987; Indomptable in 1989; Terrible in 1990; and Foudroyant in 1993.

Redoutable has been preserved since 2002 as a museum ship at the Cité de la Mer naval museum in Cherbourg-Octeville, France. The reactor compartment has been replaced by a new section.