Le Redoutable class SSBN

Nuclear Ballistic Attack Submarines (S641-651). Service 1964-1996: Le Redoutable, Le Terrible, Le Foudroyant, L’indomptable, Le Tonnant, L’inflexible S-611 to S-615

The “Le Redoutable” was the first nuclear-powered ballistic missile submarines class of the French Navy, with six built built in two upgraded batches between 1867 and 1985. First class built in continental western Europe and in 1971, France was the fourth power to join this exclusive club of the ultimate deterrence. At the time, it was part of the “triad”, one of the three French nuclear deterrence assets with the air (Mirage IV) and ground (ballistic missiles and Pluton TME). With 9,000 tonnes the largest submarines ever built in France at the time carried sixteen ballistic missiles as part of the Strategic Oceanic Force (FOST), whereas a dedicated base was built at “Long Island”, Brest. They carried the French deterrence program until replaced by the “Triomphant” class after the end of the cold war. What made their story special is that France did not developed a SSN prior, directly jumping on this type by skipping a step. Today, Le Redoutable had been preserved in Cherbourg Museum, world’s only SSBN that can be visited by the public. Her nuclear original reactor had been retired and replaced by one from a cancelled SSN. The last of the class was decommissioned in 2008 so that France could maintain four SSBNs at sea at all times, gradually replaced by lightyears ahead Triomphant class.

Programs Development

The story of the “Le Redoutable”, precisely because there was no intermediate nuclear submarine type, did not came out of thin air however, as shown by the story of the Gymnote SSB. The latter was the first French ballistic missile carrier, but a conventional one in propusion. However there was a nuclear attack submarine project already in the works since 1956. In 1955 already the government started studies on nuclear power, and in 1954 already there was Q 244, a SSN project pushed forward by PM Pierre Mendès France.

This was a massive (110 meters or 360 ft) SSN in order to firt a first nuclear core, with hopes it could be procured in the US. At first it was opposed by admiral Hyman Rickover but not by the current government. In 1957 a nuclear research center was built at Pierrelatte, with an isotope separation plant. However with the return of De Gaulle in 1958 this started to peter out as soon relations with the US started to degrade. Decision to withdraw from NATO’s integrated command stopped all discussions and killed Q 244 in the egg. France would not have its SSN before decades.
However De Gaulle approved the plan of a SSBN and pushed forward for it to be built in priority.

At the time in 1959 the French stock was 440 kilos or uranium, just enough for a land test reactor. The next year a prototype marine reactor was built in Cadarache with atom engineers working with the ordnance procurement agency, DGA. Criticality was reached in 1964. This reactor was included right away in the construction of the first SSBN, which studied started at the time, just as a submarine was launched in 1964 to test and launched ballistic missiles. This was FS Gymnote, a deeply modified diesel-electric sub partly based on the Daphne class SSK and designed by André Gempp.

With the plant at Cadarache and M1 missile test center, the Gymnote was the third part needed to have the SSBN program started.
Once again, this program of SNLE (Sous Marin Nucleaire Lanceur d’Engins), French for SSBN, was headed by the same team led by André Gempp. The new steel developed for FS Gymnote was notably based on preserved techniques of the Penhoët St Nazaire yard which built the last French battleship Jean Bart. The hull design was to be based on the USS Albacore‘s teardrop style shape.

Even before the M1, the French nuclear program had its first nuclear test, Gerboise Bleue in the Sahara desert on 13 Feb. 1960. The CEA (Commissariat à l’énergie atomique) in charge of nuclear power created a military branch (DAM) to oversee the development of carrier missiles, which concluded both with the Albion plateau launch base and the M1 ballistic missiles, developed by the Société d’étude et de réalisation d’engins balistiques (SEREB). At the same time in 1964 the Mirage IV and its AN-11 airbone bomb entered service. The large S2 ballistic missiles and Albion base became operational in 1971, the same year as Le Redoutable SSBN. In six years France had its nuclear triad, developed from 1959.

Design of the class

French SSBN development

It’s only on 2 march 1963 that a contract is signed for the first SSBN construction. This was preceded by long studies just do determine if this was doable in the first place. Cherbourg Naval Yard was contracted by the DCAN (Directorate of Naval Constructions) and the CEA working both on the nuclear core and its branch DAM. The GEB (Groupe des Engins Balistiques) directed work inside the MoD on the M1 missile. Development of the GGM S1 proceeded alongside the much smaller and compact M1 SLBM. The DMA, ancestor of the DGA coordinated from 1961 the four branches (sub construction, missile, warhead, nuclear core) ensured constant communication between the directions.

This program at the time took considerable resources: France devoted up to 1.04% of its GDP (gross domestic product), 50% of its military equipment expenditure in 1967 to the development of its nuclear deterrent forces, roughly half of which went to the SSBN. This severely restricted the naval conventional forces as well, with two carrier projects cancelled and others frigate programs downgraded. Back in 2015 the part of the SSBN budget was down to 0.17% GDP. To avoid the political versatility of changing governments the first Military Program Law (MPL) helped sanctuarize all military programs over five years. The first was voted in 1960. This helped to keep programs on schedule and on budget, inclusing the SSBNs in two batches. Indeed, the Inflexible, launched in 1985 had little to do with Le Redoutable back in 1971. These were in effect almost two separate classes, but shared similar dimensions and hull. We will dwelve into detail in these changes below.

Hull and general design

Challenges of a new super deep hull

Since France had no SSN (Nuclear Attack Submarine) to start with (both the Skipjack in the US and Valiant class in UK were taken as bases for 1st gen. SSBNs), the new SSBN had to be designed from scratch, sharing very little with the previous Gymnote apart its missile tubes. Added to this, the new hull was colossal, 128,7 meters long (422 ft) with a max external beam of 10,6 m (35 ft) plus a draft of 10 meters (32 ft) and above waterline height (“tirant d’air”) of 11 meters (36 ft) at the top of the sail (“massif”). Nominal displacement was declared to be 8,080 tonnes surfaced or standard and 9,000 tonnes submerged. To compare, the G. Washington class were 5,959/6,709 long tons and the Resolution class 7,500/8,400 long tons.

The new hull was perfectly cylindrical with a tapered stern optimized for underwater speed but subjected to roll on the surface. The vertical bow deviated from the teardrop shape and kept precisely to adress roll and stability but was discontinued in the 2nd gen. SSBNs. There was a thick pressure hull under the outer hull, separated in several modules made separately, with the same type of steel developed for the Gymnote, capable of withstanding pressure well under 300 meters (980 ft) as max operating depth. This hull was made of 80 HLES (High Elasticity Weldable Limit) steel and divided into 24 annular sections of 200 tons each, welded together. The pressure hull was not straight but was divided into two constrictions in which the main annular-shaped ballast tanks are housed. On is in the forward third and on the other behind the nuclear section. Thickness is around 50 millimeters (2 inches) for safety with coefficient greater than 2 so to withstand 700 meters deep (2,290 ft), and it’s not even the theoretical crush depth. There are T-shape section frames placed at regular intervals to reinforce the structure.

The “massif” (sail) of Le Redoutable

At 1/4 of the length are located the sail and its diving planes. Its includes periscopes, radar antenna, snorkel and open watch post when surfaced. This sail is quite unique and not sharing a lot of similarities with the previous French SSK classes of the 1950s (Narval, Arethuse or Daphne). The outer hull and skin ensured hydrodynamics efficience, covering the ballast tanks, antennas as well as the ends of the launch tubes, access panels, and sonar antennas. The pressure hull is subdivided into 7 sections (see the cutaway), all isolated by watertight bulkheads capable of withstanding the same pressures as the main hull. They are holed by two watertight doors each, and delimit three refuge zones in case of flodding. The crew communicated with the exterior via four airlocks, two of which are connected to the standard hatches and two only used for evacuation at greater depths. Three larger openings are also used to reload weaponry or replace large equipments within the pressure hull. Including one to reload the nuclear reactor with heavily reinforced openings sealed by welding but they always can be easily removed for major work.

Detailed interior construction

Diagram of the Redoutable in section (pressure hull in blue):

The thick hull is subdivided along its length into sections (A, B, C, D, E, F and G) isolated by watertight bulkheads (in blue). The pressure hull is pierced by four airlocks (s) plus three breaches (b) used only in major overhauls, notably replacing the nuclear reactor core.

The size of the new SSBNs was not only dictated by the presence of tall ballistic missiles (tranche missiles) and a nuclear reactor (tranche nucleaire) which significantly changed the traditional interior layout. Like the Gymnote (and this as partial) and most large SSNs, the thick hull is internally divided into three decks over most of her length.

Yard model of the Le Redoutable, Argonaute Exhibition.

The forward outer section housed the main sonar antenna and emerging torpedo tubes. The thick hull’s front was constructted due to the forward ballast tanks. Section F of the pressure hull is wider and truly three decks tall, making the crews quarters. Officer’s mess and upper deck, cafeteria, other crew cabins on the two lower decks. The central navigation/operations station (PCNO) in the central section under the fin is the brain, with the helm station, sonar watch stations, and plotting table.

It contains the periscopes sights, and a propulsion dashboard, and radar operators. The aft section starts right aft of the sail with missile section about a third of the pressure hull in length. Submerged it is only crossed by a passageway overhanging it. By the way, the hydrodynamic studies and relative compacity of the tubes (made for the M1 and future, larger missiles) enabled to create a low, sloped sides and streamlined shouldered missile hump. In fact this was the only design in which the “shoulder” did not started at the rear of the sail, but in front of it, the sail emerging from it.

Powerplant

At the rear of the missile section was a reduced pressure hull section due to the rear ballast tanks and comprising a second control center (tranche moteur) or “central propulsion station” with all control and command panels for the nuclear reactor, turbines and reduction. Here is located the aft escape airlock. Rear of the nuclear core is located the turbo-alternator and turbines sets, clutch, reduction gear, propeller shaft.
The core of this system is the 100 megawatt pressurized water reactor (PWR) delivering 11.76 megawatts measured at the propeller (16,000 hp). It is located inside a thick cylindrical tank with cover, from which emerge control rods. The heat generated comes from uranium rods (enriched to 80%) is evacuated by a primary water circuit superheated and maintained under pressure to avoid boiling. It went through a primary pump to the steam generator. The heat is transmitted via small submerged tubes to the water in the secondary circuit, producing high pressure steam, passed onto high-pressure turbines drivin the propeller shaft through a reducer and clutch. The steam also feeds a turbo-alternator providing all electrical energy on board, while the steam from the secondary circuit is cooled in a condenser by a seawater circuit (deep, cold external water), returning to the steam generator.

The French PWR designed in Cadarache Center is a loop reactor with separate circuits to avoid all contamination. The steam generator is physically completely separate from the reactor. The core tank is also placed on suspensers to withstand any major shocks. The steam generators and primary circuit pumps, auxiliary equipment in the nuclear boiler room are all encapsulated in an enclosure, radiation-proof, about 8 metres long for 700 tonnes and partly in lead and other compounds. Two passageways alongside leads to the rear engine section through bulkheads and watertight doors. There is also a large welded breach above the nuclear boiler room for core reload (IPER). A second breach enabled to replace the primary circuit pumps.

Le Redoutable’s Steam Turbines

Up to the reducer, equipment are duplicated for redundancy, and to increase reliability and safety. First are located two turbo-alternators installed on either side of a central aisle producing electricity, then two steam turbines connected to a single reducer. Pressurized steam circulates in large-diameter insulated pipes snaking above the equipment for free expansion. It is directed to condensers located under the main deck and via a external outlet seawater circuit, cool it down, return it to the steam generators. The single reducer is coupled to the two turbines, going from a few thousand revolutions per minute to less than 200 rpm. It was too large to be replaced via the hull breach and had to endure 30 years of service. Behind it was located the clutch to have the propeller shaft decoupled when the reactor was cold. The propeller shaft can be driven indeed by a backup safety electric motor. The electric motor delivers 11,925 kW (15,990 hp) and the two backup diesels generators were SEMT Pielstick 8 PA V 185 delivering 975 kW or 1300 hp as auxilary powerplant to run all systems on board as backup.

The tail is a classic “+” shaped arrangement, with however a slightly taller upper tail. The propeller is a new model which shape was refined tin hydrodynamic tests, in hardened cast bronze (the seven blades are fixed indenpendtly to the hub for easy replacement). The 7-bladed arrangement inspired by other western subs was a logical choice to avoid cavitation, with a large diameter, reworked shaped and low revolution. The French started to study the installation of a shrouded propeller on FS Inflexible in 1982, but reserved it for the 2nd gen. Triomphant class. It is difficult to know how much the propulsion was rafted and isolated to avoid external noise, especially the transmission’s reducers. What is certain is that the next Rubis class SSNs, smallest in their category, had no similarities with the Redoutable (they were instead based on the conventional Agosta class) and were considered among the noisest SSNs in the 1980s until their refit. There are also assessments about the 1990 Le Triomphant class machinery rafting and that gives some clues by default on the redoutable class. It is assumed the acoustic isolation was rather similar to 1960 NATO standards, and still ahead of Soviet contemporary subs.

Armament: 16 Ballistic Missiles

“Tranche Missile” with M4 and M45 (inside) and M51 (outside) for the planned 3nd gen. SSBN.

Due to the duration of the class between 1971 and 1986, the main armament, sixteen SLBMs, varied in time, from the M1 to the M4. The M1 was a 1st generation SLBM, and was short-ranged, obliging these subs to patrol along the Norwegian coast or gulf of Genoa. The M1 was retired from service in 1975, replaced by the M2 until 1978, then the M20 with MIRVs, whereas the M4 with a new 6-MIRV warheads entered service in 1985 on FS Inflexible. The term for SLBM in French is MSBS for “Mer-Sol Balistique Stratégique”. The development started from April 1962 when France signed final agreements with Algeria, leaving the country and evacuating the Sahara test range in July 1967. Three months later a center was created near the Bay of Biscay, the Landes (Biscarosse) site allong to launch missiles over the Atlantic to 3000 km with an RV impact area near the Azores, which required a tracking station from October 1966 on Flores island.

Walkway between missile tubes on Le Redoutable

The M1 missile, which initially equipped the first two, had two solid propellant stages with in between a pyrotechnic separation device, and in the second stage an equipment compartment with the inertial unit, guidance computer, control unit and second stage separation system to the warhead, single nuclear charge with thermal resistant re-entry body. The internal tube could move inside the flooded external tube with suspensions. The external tube extended above the pressure hull, covered by the outer hull’s hump, with a sliding mat between the missile and internal tube. The tube is closed by a hatch door opening outwards with a neoprene membrane preventing seawater ingress in the tube after opening, just before launch at shallow depth. A flushing system with compressed air expelled the missile towards the surface at 100 km/h, through the neoprene membrane, and ignited. The “missile tranche”

M1 SLBM (1969)

The M1 is the French intermediate-range ballistic missile that was operated by Gymnote and later on the first two French nuclear-powered ballistic missile submarines of Le Redoutable class. This missile has two solid-propellant stages and carried a single MR 41 nuclear warhead rated for 500 kt TNT equivalent, range of 2,450 kilometers. It was Deployed from 1966 when fire tested but operationally from 1971, with 16 missiles carried on Le Redoutable class. Short ranged, it was quickly replaced by the M2 (range 3,000 kilometers) in 1974.
The M1 had a launched mass of 20 t for 10,67 m (35 ft) in height and 1,49 m (5 ft) of diameter. The range was a serious issue as the carrier needed to be positioned in the Norwegian Sea or in the Gulf of Genoa, busy, narrow seas too resticted to allow patrolling without being detected.

M2 SLBM (1973)

The M2 MSBS was the 2nd gen. French SLBM, with two stages, deployed on the Redoutable-class from 1974 to 1978, replacing the M1, and replaced in turn by the M20 MSBS from 1977. As early as 1958, the French Navy requested a range extended to 3,000 km. New versions were quickly developed and the M1 only armed the first two SSBNs in class. The solution chosen consisted of increasing the propellant mass of the second stage by two tons, by positioning part of the nozzle inside the body of the booster not to significantly increase its length . But development of the second stage was difficult, with nozzle, booster casing and thermal protections needs fixing. It was nevertheless in service from 1974 as planned and extended the range to 3,200 km, making for a larger patrol area albeit still not ideal.
The payload is the same as M1, with a MR 41 atomic bomb, yeld 500 kt. The M2 was a transitional model, and only equipped the first two submarines, Le Redoutable
and Le Terrible. The tubes were reworked on the next batches to carry the M20.

⚙ specifications M2 MISSILE

Gross mass: 19,500 kg (42,900 lb), Payload: 1,360 kg (2,990 lb).
Dimensions: 10.67 m (35.00 ft) x 1.52 m (4.98 ft), span 1.52 m (4.98 ft).
Propulsion: Solid booster rocket, 2 stages. Thrust: 440.00 kN (98,910 lbf).
Max range: 3,200 km (1,900 mi). Speed: Mach 8+ Apogee: 600 km (370 mi).

M20 SLBM (1977)

The M-20 is the third gen. SLBM, to replace the M-2 in 1977. Enough were built for all Le Redoutable class, so 96 plus reloads.
The M-20 is a two-stage solid-fuel intermediate-range ballistic missile, longer and with a launch mass of 20 tonnes, 3,000 km ranhge with the CEP ( accuracy) of 1,000 m. The first stage is controlled by vector thrust (four nozzles), second by a single one. It us fuelled by hydroxytelechelic polybutadiene, first stage 9.86 tonnes (burnt in 58 seconds), second 5,900 kg (burnt in 90 seconds) and intertial guidance.
The payload contains penetration aids and a reinforced atmospheric reentry vehicle but no MIRV, the military charge remained a single TN 60 nuclear warhead with 1.2 megaton yeld. The M20 was gradually replaced from 1985 by the M4 with greater range (5,000 km) and 6 MIRVs.

⚙ specifications M20 MISSILE

Launch Mass: 20 t, Payload 600kg TN 60, thermonuclear.
Dimensions: 10,67m x 1,52 m (same as M2)
Range 3 000-3,200 km

M4 SLBM (1985)

The development of a brand new generation of SLBM, the M4 (The M3 was a shelved project), was decided in 1973. Developments started in April/May 1974, led by Engineer Jacques Chevallier, Director of Military Applications at the CEA. It had three stages making for a 5,000 kilometers range, carrying thermonuclear MIRVs. Its mass and dimensions were greater than those of the M20 with a 35 tonnes weight, 11.5 metres lenght for 1.9 metresdiameter making it incompatible with the Redoutable class initial design (first two). From the Le Terrible (2nd of the 1st batch), the space available in her tubes were modified in her first IPER (overhaul) and the last modified duirn construction. Thus only Redoutable, the lead boat was not modified for cost reasons, she was already old.

Inflexible was the only one designed from the outset to carry the M4 and was delayed until 1985, at the end of the M4 tests. Between 1985 and 1993, Le Terrible, Le Foudroyant, L’Indomptable and Le Tonnant had their tubes recast in turn for the M4 missile during their programmed IPER. The M4, unlike previous missiles, was developed by Aérospatiale and from 2016, Airbus Safran.
The initial M4-A had six TN 70 warheads, 150 kt each, 4,000 km. These MIRVs were designed to fall in clusters in a 150 km long, 120 km wide pattern.
The next M4-B version entered service in December 1987 with six TN 71 warheads and range of 5,000 km.
The last M-45 was developed for the next Foudroyant class SSBNs (SNLE-NG) and never entered service with the Redoutable class. Range 6000 km, entering service in 1997. The M4-A missile was withdrawn in 2001, M4-B missile gradually replaced by the M45 missile from October 1996 until 2005.
Theere were 16 active warheards, 96 in reserve in park by 2002 between the M4A and M4B whereas 192 M4 are in reserve and 32 active with the new Foudroyant class.

⚙ specifications M4B MISSILE

Mass: 35t, payload 6 MIRV TN-71 150 kt
Dimensions: 11.05 x 1.93m
Populsion 3 stages, Range: 5000 km (4000 M4A)
Guidance: Inertial, Accuracy (CEP): 300m (980 ft)

Torpedoes and Encapsulated Missiles

The Redoutable class had four bow tubes, located above the main bow sonar. Side tubes enabling to free the whole hull nose cone for a larger array was introduced in 1990 for the Triomphant class. The torpedoes initially used were initially of the DTCN L5 type, later replaced by DTCN F17s.

L5 Torpedo

The DCTN L5 is a 930 kg torpedo, 4.4 metres long and 533 mm in diameter. It carries an explosive charge of 150 to 200 kilograms. Top speed is 35 knots and range 9.5 kilometres. It was pureley defensive.

F17 Heavyweight Torpedo

The F17 is a heavier torpedo of 1,41 tons, 6 metres long, carrying 250 kg of HBX-3 explosives. Its range is between 18 kilometres at 35 knots or 29 kilometres at 24 knots but it is wire-guided torpedo (copper wire) and has an active/passive sonar for final guidance, after the cable is snapped and target acquired. A far better weapon, it stayed in service until the end of their career. About 12 torpedoes were carried. The F17 was replaced by the F21 on the SNLE-NG.

Exocet Missiles

Only from the M4 refit onwards (not applied to the lead boat) the Exocet SM39 mod2 anti-ship missile is carried, encapsulated. It is ejected with compressed air by the torpedo tube, the capsule is jettisoned when broawhing surface (sensor) just as the missile’s rocket engine ingnites, and starts a gradually faster flight phase at subsonic speed, skimming to avoid enemy radars. It carries a heavy explosive charge up to 50 nautical miles (90 km) in that 1985 version.

Command and Control

The Central Navigation Operations Station (PCNO) shared space with the pilot and navigation plotting team. Threats are determined there, weapons system managed all in the upper deck, immediately below the sail’s bulkhead. It is partially partitioned and occupied by the watch leader CC head, helmsman, radio operator, two sonar operators, a diving safety operator, a tactical situation operator and inertial units operator but in wartime, it could be increase to 16 including the commander.

Tactical Console

The piloting station faced forward, port side with two stations, each with a joystick for the steering bar and diving bar. Indicators shows depth, azimuth, and underwater speed. There was also an autopilot with necessary corrections based on bathymetric data and digitized maps. Diving and steering controls could be decoupled. Diving indicators are located on five bays aligned along the starboard bulkhead (central diving safety panel) to monitor and act on sub-systems such as pumps and ballasts, for precise trimming. Aerials (periscopes, antennas located in the mass) are raised or lowered also from there adn water inlets, hull openings and fire outbreaks monitored and acted there as well as anomalies detected on decentralized stations back in the reactor, propulsion, air regeneration systems. The Missiles are launched however from an adjacent firing console on the lower deck.

The raised platform in the CC is the space to operate three periscopes for surface observations (navigation and combat) one with IR channel. The upper part is hoisted using servo-controlled systems. The attack periscope had a the most reduced diameter, hooded sight to avoid reflections and camouflage. The larger surveillance periscope includes the radar antenna and radar detector and could be hoisted to a variable height. The third is the larger astral sighting periscope used to recalibrate the submarine’s inertial units.

Sensors

The Redoutable had a suite of sonars dislayed and centralized in the CC, in a semi-enclosed room located along the starboard wall, monitored by two operators permanently (on quarters), one for distant sources and the other for close sources over 360° on frequencies ranging from 20 Hertz to 1000 kilohertz. Passive sonars are used at all time, but there is a combat active sonar ready for use in closer engagements and never used in practice.
DUUV sonar: Active surveillance/attack sonar. Main cyl. antenna in the forward chin, second aft of the sail but with poor restitution (propulsion interference) for amplitude and bearing of the sound source.
DSUV Sonar: Low-frequency medium-range passive sonar, antenna located in the bow, above the DUUV.
DUUX acoustic rangefinder: Three detectors to determine azimuth and distance by triangulation.
DSUV: Towed sonar, very low Frq. passive) with many hydrophones on long cable.
QSUA: Monitoring suite for the own sub’s noise with detectors close to sound sources on board.
Navigation sonar suite: Bathymetric system which data helpes safe navugation under ice or in shallow waters:
Comprised the AN/UQN deep-sea sounder, AN/BQS ice detector, NUUS swell measurer (amplitude and direction) before a missile sequence.
Navigation is also helped by three Sagem (now Safran) inertial navigation units recalibrated by the periscopic astronomical viewfinder.
This comprises a Thomson CSF DRUA 33 nav radar (band I) and Thomson CSF ARUR 13 radar detector. They are raised over the sail when surfaced.

Communication

Permanent radio standby to receive critical persidential instructions comprised underwater receptors. The radio room is located in the CC, but completely closed with restricted access to the operator, captain and XO and working on 24-hour shifts. Radio transmitters/receivers uses different wavelengths two of each for backup. Underwater, the system uses low and very low frequency through a towed wire antenna held under the surface. When surfaced, UHF (short range) and LF are used, deployed on demand at the top of the sail. For inter-fleet communications there is an acoustic wave telephone TUUM 43.

Author’s rendition for Helion’s a sword for peace and liberty vol 1 force de frappe FR

Career of Le Redoutable class SSBNs

The previous, first French SSN was given the construction number Q244. The identification number, S611 was not changed unlike US subs for example to SSN-611 and its construction started in 1958 was abandoned as no US pressurized heavy water reactor could be obtained. What was built was recycled into the Gymnote SSB, which helped to develop the missiles tubes operated by the Redoutable then planned after decision was signed on March 2, 1963, and Q-252 project as hull number.
Construction started at the end of 1964 in Cherbourg, based on the plans from André Gempp. She was launched 29 March 1967 in Cherbourg, in presence of General de Gaulle and under command of frigate captains Bernard Louzeau, Jacques Bisson, commanding each one of the two crews (blue and red).

On 25 September 1970, she left her dock at Brest arsenal for Île Longue (“Long Island”) Crozon’s, Camaret-sur-Mer highly secured naval base, built on purpose. The facilities includes one large open dock, two enclosed drydocks for full maintenance, missile storage facilities, torpedo and antiship missiles stores, and workshops for 1,500-2,000 personel. The base was built from 1967 to 1970. Nearby, but out of the island are located the training and instruction center for SSBN crews with simulators, for constant training between alternated patrols at sea and initial training.

On 1 December 1971, Le Redoutable entered active service within the Strategic Oceanic Force (FOST) under command of captain Louzeau and equipped with sixteen M1 SLMBs. For the first fifteen years of French nuclear deterrence development (90 billion Francs) 12% went to the first SSBN, which operated in her patrols two crews for regular totation just as other SSBNs in order to maintain her presence, 135 men each (120 men, 15 officers), Blues and Reds, ensuring, when the last sub was delivered in 1985 that France had six SNLEs operational four at sea, three in their variable firing areas and one in transit, then two in maintenance, and possibly IPER (major overhaul).

On May 29, 1971, the first M1 launch at sea on Le Redoutable “Operation Onagre” was performed with an M1E while submerged. She started her first patrol on January 28, 1972 for 55 days. Towards the end of her caeer these were longer, up to 75 days at sea. In her long career however she was the only one not upgraded to the new M4 missile.

When sailing out, she was escorted until “dilution” (start of her underwater deployment) by a frigate and/or destroyers and a SSK or SSN (from 1986) and preceded by at least two Super Frelon ASW search helicopters, to avoid any trailing Soviet sub. France had no forward operating base unlike the US at La Rota, Spain or in Scotland. All trips are from and to Long Island, Brest.

In 20 years of service, she carried out 51 patrols, 3,469 days at sea, 83,500 hours underwater (11 years at sea, 10 underwater). She was withdrawn from active service on 13 December 1991, stricken on 24 July 1992. After removal of her ballistic missiles, she made a crew change in Dakar in April 1991, supported by the TCD Orage (Operation Jubarte), testing such operation far from base. This was the one and only such stopover in African in the history of French SSBNs.
On 7 October 1991, she returned to Cherbourg, not Brest, where her manufacturer, naval construction department, started the dismantling, over two years. In 1993, the reactor section was separated and stored for upcoming decades in a specially designed anti-seismic precinct in the Homet military zone, before final storage on an ANDRA3 site.

On 19 January 1996, the Ministry of Defence decided to donate the Redoutable to the Cherbourg Urban Community in order to create a local attraction for the future Cité de la Mer being built here. The conversion into a museum was carried out at the Cherbourg arsenal with an investment of 25 million francs financed by the MoD. It was believed the SSBN, stripped of anything confidential, would raise awareness in France on deterrence. To accommodate her, it was necessary to create a suitable dock, dug in the northern part in open air from June 1999. The dry dock is purely civilian and tailored, not capable of being flooded again and accomodate a tug as well as high above mean sea level. Entering it was complicated, at high tide in exceptional circumstances. The transfar was done on 4 July 2000, and she was beached on a line of tins until fuly stabilized over a few days, then the basin was close, with sheet piles dried out. She was open to the public on April 29, 2002. The nearby museum is dedicated to development of naval nuclear propulsion, underwater exploration and the Strategic Oceanic Force.

Le Terrible (S612) was the second nuclear-powered ballistic missile submarine of the French Navy, launched in Cherbourg on 12 December 1969, commissioned on 1 January 1973. For 23 years, was a part of the French nuclear deterrent force. She was the first upgraded to the M4 standard, after Inflexible, built for it.
She was decommissioned on 1 July 1996, replaced by the new SSBN “Le Triomphant”. Her nuclear unit was retired and she is currently awaited dismantling scheduled between 2018 and 2027 in Cherbourg by DCNS, Veolia and NEOM (Vinci) tasked to do the same with all remaining SSBN of Le Redoutable class.

Patrol details remains classifed but they followed always the same pattern:
Two crews take turns on board. When the red crew returns to its home port in Brest, it goes on leave for 5-6 weeks after 4-days handover to the blue crew and vive versa and underwent 6 weeks of (re)training on land before swapping in turn. Before taking turns, Blue crew is taking part of the SSBN’s reconditioning carried out between two patrols by DCAN (also some cleaning, minor repairs, gathering and checking supplies). The submarine leaves Brest accompanied by ships (see above) and dives as soon as it has sufficient depth or passed the Continental Shelf. She ensured her trail is lost by following a random trajectory, limiting her sound signature to a minimum at moderate speed. The position from there is only known by the commander, XO and navigators. She remained submerged until back from patrol (55-70 days). While deployed she gains an area to be concealed while remaining at a useful pre-determine missile distance from its potential targets. It went on these SSBNs from the Norwegian Sea to more open ocean.

Officer’s quarters

The SSBN also remains at all tim in one-way communication with the Presidency and Naval HQ. The crew is divided into three thirds for an effective 8-hours service, 8 for maintenance/troubleshooting, 8 R&R and sleep. In all seven watches of unequal length per 24-hour and in night phase, red lighting is on to mimick alternance. Family ties are allowed via, once a week a single message limited to a few dozen words, through the Commander’s censorship. The routine is cut by missile firing simulations, fire/water drills. For fire efficiency inertial units are always checked and recalibrated for always keeping an exact position.

The Foudroyant (S610) is the third SSBN of the Le Redoutable class, laid down in 1969, completed in 1974 and originally equipped with M1/M2/M20 missiles, but overhauled in 1990-1993, to the new M4 missile standard. She was the first equipped with a GPS designed by SAGEM. She was withdrawn from service and decommissioned on April 30, 1998. She is awaited its dismantling scheduled between 2018 and 2027 in Cherbourg by DCNS, Veolia and NEOM, the process started in September 2021 and endded by late 2022.

L’Indomptable (S613) was the 4th SSBN of the class, launched in 1971, starting her career in 1976 within the FOST. Like her sisters she was equipped with the M1/M2/M20 before her major overhaul from December 1987 to June 1989 to the M4 missiles and SM39 anti-ship missiles. She was the second equipped with a Global Navigation System from Sagem. Withdrawn from active service, she was decommissioned on April 6 2005 in Cherbourg, awaiting dismantling. The extraction of the reactor unit took place in 2015. Dismantling, was scheduled between 2018 and 2027 in Cherbourg and proceeded by DCNS, Veolia and NEOM from March 2020. On November 18, 2020, a fire broke out on the site, quickly brought under control. Work could resume in the afternoon. The process was completed in September 2021. She was was the subject of a documentary: “Sous-marin nucléaire: déconstruction XXL” (Ah! Production, RMC channel).

The Tonnant (Thunderer, S614) was a French SSBN, 5th of the Le Redoutable class and in service between 1980 and 1999. She was laid down on October 19, 1974, launched on September 17, 1977, commissioned on April 3, 1980, and signed in for the FOST, kept in sevrice for 19 years.
PM Pierre Mauroy spent two nights on 11-13 November 1981, during a visit to the facilities in Brest.
From 1 February 1985 to mid-April 1987 and 19 October 1987, she had a double overhaul, the “M4 overhaul” carried out in Cherbourg and core change (IPER), as well as updating other systems to stay in service in the 2000s.
On 14 May 1987, a gaping hole was found in her sail: The door and hinges had been torn off, the hull dented. This was attributed to whales at first and then the date matched a collision by the Concarneau trawler “La Jonque” which sank with all hands the same day off Ouessant.
In July 1994 and May 1999, Le Tonnant took part in “Pilou” exercises off the coast of Brest. She was to simulate the rescue of a submarine crew in distress using a US Navy DSRV, small rescue submarine of the Mystic-class for interoperability tests. She carried the DSRV which was connected to a submerged Agosta-class submarine, Bévéziers.
Tonnant was decommissioned on 16 December 1999, replaced by a Le Triomphant class SSBN. She awaited demolition in Cherbourg whuich was initiated on October 2016. After two years of preparation of the facilities in Cherbourg she was first submarine in class to be dismantled. The operation started on September 11, 2018 and lasted 18 months by Naval Group, with Veolia and Neom (Vinci, for asbestos removal). Nearly 87% of her mass was be recycled, including 1,500 tons of special steel, 2,000 tons of ferrous steel, 1,000 tons of non-ferrous steel, copper and stainless steel, and 800 tons of lead. The mass of asbestos waste is estimated at 210 tons and the operation was completed in March 2020.

The nuclear-powered ballistic missile submarine L’Inflexible is the last Redoutable-class built by France, hull number is Q264, visual designator is S615.
Decision to build her was made on April 20, 1974 but suspended in June 1976. The steel planned for her was diverted to the construction site of the Rubis nuclear attack submarine (S601).
The Defense Council of September 27, 1978 relaunched the project with specification to carry the M4 missile. This was registered in the 1977-1982 Military law.
She also benefited from a new design intended to increase her acoustic discretion. Hhull shapes were modified, a new rudder was designed. The propulsion and electrical plant were rafted and all elements placed in cushioned suspenders. The information processing system was also completely new, with high-powered pooled computers and digital communication. The tactical weapons system was also brand new and used for a new multifunction sonar and better manage the Exocet missiles. The global navigation system was also completely renewed, with the latest navigation and radiolocation equipment. This configuration became standard for the mid or late life main overhaul of her sisters via IPER.
Construction was carried out by assembling 50 tones prefabricated, pre-wired sections, all 11 metres in diameter. The assembly and “keel laying” started on 23 March 1980 under 7.5 million hours of work and approx. 600 million euros to 1985 Francs equivalent.

Inflexible entered service on 1 April 1985 and integrated into the Strategic Oceanic Force homeported at Ils Longue sub base, Brest and directly armed with M4 missiles. She performed many patrols between her two periods of major unavailability (IPER) lating for c72 months. She was modernized in 2000-2001 to receive the M45 missiles, first of her class, sharing the same capabilities as the Le Triomphant Class.
The Inflexible was withdrawn from service in January 2008, shortly before Terrible (Le Triomphant) entered service. Her nuclear unit was retired and she awaited dismantling, to be performed before 2027 in Cherbourg. Work started on January 23, 2023, lasted 16-18 months.

General Assessment

The construction of the first French SSBN really started ten years after De Gaulle came to power, which was moderate given the whole French deterrence program came from scratch. Construction went for almost two decades, from the first keel laying in 1967 to the last in service in 1985, enabling upgrades between the ships, until Inflexible, which became the template for upgrades ported to the others. Their new 80 HLES steel (high elastic limit weldable) allowed diving to 300 m in normal, peacetime use, and more than 700 in combat and was roomier than anything that came before with three decks and sections over a total area of ​​240 m2. Even wiht crew quarters limited to a 20m section at the front, the livability standards were much greater than on previous French submarines, with proper, individual berthing for all crew members insted of shared mats, and high standards in terms of air conditioning, internal spaces distribution, air recycling, water distillation, and internal paneling giving the impresion of cleaner, leaner interiors. Many aspects necessary for the life on board of a crew of 130 over two months in permanent submersion were taken in consideration. Immenses progresses were done in terms of living conditions via organization and methods in order to raise gradually the patrol time from 55 to 70 days.

For a first SSBN, they were relatively successful, albeit between their noise level and the first short ranged SLBMs they carried. The M1, M2 imposed dangerous launching areas, whereas the M20 and especially the M4 later gave a far more comfortable “reach”. Construction was not smooth sailing and without any informations on US SSBNs unlike Britain, France had to discover and solve many technical by itself. André Gempp chose a new steel allowing to reduce the mass by 20%, a derivative of WW2 armour plating, flexible, light, while being highly resistant but further modified by adding elements giving it the necessary mechanical and weldability qualities. During construction, calculations indicated at first thes needed to add 1,300 tons of ballast to be balanced, but as the project progresses and additions piles up, the margin became negative and the upper part of the hull neded to be trimmed down. All these boats were built with traditional methods, from the keel up, until the Inflexible, which was a sub-class of herself.

The Redoutable class ships proved to be reliable in service with only one patrol interrupted following an attack of appendicitis to a doctor than needed to he heliborned to the nearest hospital, and a fire in dismantling phase, quicky put down or a collision with a trawler. They remained in service from 20 and 29 years with at least 2-4 yearly patrols, for sixty on average given they had four years in overhaul. Indomptable had the record, as she carried out 125,000 hours underwater or 14 years.
General de Gaulle’s choice to developed a home-grown nuclear industry and deterrence strategy, independent from NATO or the United States, was a costly and risky endaevour that paid off. This created the foundations for a whole, high-end section of French industry with military and civilian applications (nuclear power plants and Ariane launchers) or dual (inertial systems, GPS, solid-propellant propulsion, special steels) which became pretty unique in Europe. The first SSBN was also a base on which to create a far better SSBN, skipping steps. Despite De Gaulle’s departure and later decease in 1970, his successors continued the deterrene program, even with a major political alternance in 1981. It was never questioned since, albeit its format had been reduced.

Succession: The Triomphant

In a sense, this class was a cold war project, initiated by Pdt. F. Miterrand of the new socialist majority. The project was named “SNLE-NG” and aimed to replace the first batch of four boats of Le Redoutable class to maintain six serviceable submarines, the second part being on the development of sucessor missiles, the M4 and then M51 to keep the last two of the class relevant until replaced in the 1990s.
The strategy of nuclear deterrence needed a replacement with new detection systems using low and very low frequency waves and the 1960s design which no longer fit modern silencing technologies.

The core objective was to design a new SSBN that would be “1000 times quieter and ten times more sensitive”. To escape detection she would have to dive deeper as well asn this required yet another new steel. The tonnage was recalculated and made a spactacular jump to 14,000 tonnes, notably to accomodate noise attenuation systems and carry a larger, new generation of missiles. To increase availability and interval between major refits it was decided to increase service tilme between major refits from 6 to 7.5 years. For names, the Navy was rather conservative and retook the tradition of XVIIIth ships of the line, with “Le Triomphant” (Triumpher”), planning yet again six units. However in 1989 the Berlin wall fell and in 1990-91 the USSR collapsed and the cold war ended. Suddenly there was not clear enemy against which maintaining a large SSBN fleet. It was decided to stick to a “minimum” of four (2 in place at sea, one in transit, one in refit). The same format was adopted by UK as well. Construction of Le Triomphant started 1986, delivery of the last one was delayed until 2010. The next generation (SNLE 3G) program was started in 2024, for a delivery expected FY2035 for the first one. No name had been assigned so far. They will have four decks and a displacement at least of 15,000 tonnes for 150m. There are also the option to reconfigure the actual Triomphant as cruise missile carriers (SSGNs) FY2035-40 instead of just recycling them.

Read More/Src

Books

Claude Huan et Jean Moulin, Les sous-marins français 1945-2000, Rennes, Marines éditions 16 février 2010
Christian Herrou, Warships : Navires de guerre: L’Union Européenne – European Union, Marines Editions 1997
Bernard Prézelin, Flottes de combat 2006 : Combats fleets of the world, Ouest-France, 2006, 1260 p.
Frédéric Stahl, « La Marine nationale 2004-2005, tome 2 », Navires & histoire, Lela Presse, no 2 HS,‎ 2006
Claude Huan et Jean Moulin, Les sous-marins français 1945-2000, Rennes, Marines éditions, 16 février 2010

Links

on fr.wikipedia.org/ excellent article
meretmarine.com/ cherbourg deconstruction old snle
opex360.com/ dga launched deconstruction Redoutable
archive.wikiwix.com/ meretmarine.com 1st underwater salvage in europe
senat.fr/questions/
seaforces.org/ Le-Redoutable-class.htm
netmarine.net/ tonnant/
netmarine.net/ indomptable
en.wikipedia.org/ Redoutable-class
dark-tourism.com le-redoutable
immortalwordsmith.co.uk le-redoutable/
seaforces.org/ Submarine/Le-Redoutable-class.htm
cmano-db.com/submarine

Videos

Model Kits

Several kits, from Polar Bear, Heller and L’arsenal or Grigorov

3D