Submarine missile carriers are the backbone of France's strategic nuclear forces.
One of the most effective components of the French nuclear dyad are nuclear submarines armed with ballistic missiles. rockets. Therefore, the French leadership has always strived to maintain their combat readiness at the level of modern requirements for naval underwater nuclear systems. weapons.
The French government announced its intention to create a nuclear-powered nuclear force in 1955. To reduce the timeframe, the launch vehicle and its missile armament were developed simultaneously. Work proceeded in parallel. In 1962, a commission was established to coordinate the efforts of seven bureaus developing the system's components: the submarine nuclear reactor (SNRP), the ship-launched ballistic missile (SLBM), the hull steel for the submarines, and the general shipboard and specialized systems of the future SSBN.
The primary challenge was the nuclear backing for the nuclear weapons and submarine launch vehicle programs. Lacking facilities to produce their own enriched U-235, French physicists began developing a nuclear reactor operating on low-enriched fuel. At the same time, work was underway to create a French nuclear bomb. In 1959, France succeeded in purchasing 440 kg of highly enriched U-235 from the United States, and just a year later, in 1960, it detonated a nuclear device of its own design in the Sahara Desert.
By the time construction of the nuclear-powered submarine—a nuclear weapons carrier—began, a uranium enrichment plant was built in Pierrelatte. This solved the problem of supplying the submarines under construction with nuclear fuel. The keel of the first French SSBN of the Redoutable class was laid in Cherbourg in March 1964.
Unlike the American SSBNs, the Redoutable-class submarines were designed without a prototype. They were the first French SSNs and later became the prototype for the Ruby-class multipurpose SSNs.
Redoutable
All Redoutable-class SSBNs were built at the Direction des Constructions Navales (DCN) shipyard in Cherbourg.
The submarine is interesting because, unlike the American SSBN Lafayette, it had seven compartments instead of six. For safety, the nuclear power plant was housed in a separate compartment.
The boats were built using a mixed architectural and structural design: a 2-hull set over the bow and sixth compartments, and a 1,5-hull set over the rest.
The main power plant was a GEC Alsthom PWR K15 pressurized water reactor with forced circulation coolant and a thermal output of 150 MW. The reactor was designed and manufactured in France without the participation of any foreign companies.
A distinctive feature of the Redoutable was the absence of a "reduction gear"—the main turbo-gear unit (GTZ). The boat had an electric propulsion system, with the electric propulsion motor (EPM) powered by independent steam-turbine generators.
This design eliminated low-frequency noise from the gas turbine engine and ensured quiet operation over a wide speed range. This design was subsequently implemented on all French submarines. It has now gained worldwide recognition in submarine construction.
Backup power was provided by four 850 kW diesel generators and a battery. The diesel-electric power plant could give the submarine a cruising range of up to five thousand nautical miles.
The bow contained two retractable thrusters (RT), which provided the ship with maneuverability at low speeds and when mooring.
At various stages, the Redoutable-class SSBNs were armed with M1, M2, M20, and M4 SLBMs. The final boat in the series, the Inflexible (S 615), was armed with M45 missiles.
Information: The M1 Mersol SLBM is a two-stage, solid-fuel missile weighing 18 tons with a single-warhead MR-41 warhead with a yield of 0,5 megatons and an inertial guidance system. The launch weight is 18 tons, and the firing range is 2600 km. The CEP is approximately 2300–3200 m. Since 1969, it has been installed on the first two SSBNs, the Redoutable and the Terible.
S. Ketonov wrote about the missile weapons of the French missile carriers in an article France modernizes submarine-launched nuclear missileLet me remind you of some points from stories missile weapons of French SSBNs.
In 1974, the M2 SLBM entered service, featuring a lightweight second stage (steel replaced with fiberglass), improved propellant, new avionics, and a TN-60 warhead. Its range was up to 3200 km. The CEP was reduced to 2000 m. However, only one ship, the Foudroyant (S 610) Thunderer, was armed with the M2, which entered service in June 1974.
In 1976 on fleet The M20 was delivered with the TN-61 warhead, which differed from the TN-60 in its reduced weight and improved resistance to nuclear blast damage. Its CEP was reduced to 900 m, and the warhead yield was increased to 1,0 Mt. The SLBM's storage and launch system was similar to the American Mk 21, but the silo was larger in diameter. The missile was fired by compressed air stored in cylinders in the submarine's hold.
The missiles could be launched from depths of 15-20 meters, as well as from the surface. This allowed for combat duty at base. By 1981, five SSBNs had been re-armed with M20 missiles.
In 1985, the M4 SLBM entered service. It was a three-stage, solid-fuel missile weighing 36,2 tons. Its first stage was made of steel, while the second and third stages were made of Kevlar. The missile carried a MIRV-type reentry vehicle with six TN-70 independently targetable warheads (MIRVs) with a yield of 150 kilotons each.
The M4 cost the French 37 billion francs. It became the first French second-generation SLBM capable of engaging multiple targets simultaneously. Its launch range increased to 4000 miles, and its kill zone was approximately 20,000 square kilometers. At the same time, the warhead's CEP (6 x 150 kt) was reduced to 400-450 meters by installing a three-axis gyrostabilized platform. (The warhead's deployment zone was 80 x 240 km.) The missile carried an air defense system and was capable of penetrating enemy missile defense systems.
The M4 storage and launch system replicated the Mk 35 system for the Trident 2 SLBM. The missile locking mounts inside the launch tube were replaced with several obturator rings. The top of the tube was sealed with a special domed membrane made of asbestos-reinforced phenolic resin. The missile was launched using a vapor-gas mixture from a PAD. The launch depth increased to 25 meters (compared to 20 meters for the M20). The ability to fire from the surface was retained. Launch preparation time was 20 minutes, and the interval between launches was 15-20 seconds (according to other sources, 60 seconds).
The M4 SLBM had two modifications: the M4/TN-70 and M4/TN-71. The M4/TN-70 had a range of 4000 km, while the M4/TN-71 had a range of over 5000 km. The increased range was due to new fuel and a reduced warhead weight. The last SSBN, the Inflexible (S 615), carried the M4/TN-70. As new SLBMs were produced, the boats were upgraded to M4/TN-71 missiles. This procedure cost the French Navy an additional 14,5 billion francs.
French SSBNs underwent repairs every two to three years, with their nuclear reactor cores refueled and modernized every five years. Two submarines (Tonnan and Foudroyant) were modernized at the Cherbourg shipyard, and the other two (Indomfable and Terible) in Brest. The work lasted approximately 30 months, and labor costs were only 20% less than for a new submarine.
Further improvements to the missile armament of French SSBNs led to the development in October 1996 of the three-stage M45-class SLBM (weight – 35 tons; length – 11,05 m; diameter – 1,93 m; range – 6000 km; CEP approximately 350 m). Warheads: 1-6 TN-75 warheads of 100 kt each, with a warhead deployment zone of 150 x 350 km. High target engagement accuracy was ensured by an INS with computer-controlled payload.
The M45's first stage was made of steel, the second of fiberglass (using a winding method), and the third of US-produced Kevlar-49. The warhead contained lightweight, high-speed, stealthy, independently targetable warheads with enhanced resistance to nuclear blast damage. The SSBN Inflexible (the last submarine in the series) was refitted to carry M45 missiles.
In 2004, the French Ministry of Defense announced plans to replace the M45 with the M51 missile by 2010. However, the last M45 missile was only retired in 2016. Following the modernization, all Triomphant-class SSBNs use the M51 missile.
The tactical weapons of the Redoutable-class SSBNs included SM-39 Exocet anti-ship missiles and ECAN F17 mod 2 remote-controlled torpedoes or ECAN L5 mod 3 homing torpedoes. American and British SSBNs did not carry anti-ship missiles at that time.
Another feature was the ability to fire torpedo tubes while the ship was maneuvering at high speeds. The submarine could safely discard defective weapons. Two of the four torpedo tubes were equipped with a pneumatic piston with a telescopic rod, which pushed the defective torpedo overboard. This system was installed on all subsequent French submarines.
The Redoutable-class SSBNs had an interesting approach to operating them. Each hull was assigned two operational crews ("blue" and "red") and one technical crew ("green"). The operational crew consisted of 15 officers, 102 non-commissioned officers, and 18 (!) sailors. All were professional contract soldiers, ensuring a high level of maintenance and operation of the equipment.
This allowed the SSBN Redoutable to serve for 7000 days, 3500 of which were spent at sea on combat patrol, including 3458 days submerged, completing 58 combat missions with an average duration of 59 days each. ("Nevsky Bastion." A. Karpenko).
Triomphan-class SSBNs are a new step towards improving the nuclear forces
The new generation of French SSBNs and the replacement for the first six French Redoutable-class strategic missile submarines are the Triomphant-class missile submarines – a series of four French nuclear-powered strategic submarines built between 1989 and 2009.
Photo of a boat on the slipway
They were built under the Strategic Nuclear Forces Development Program for 1987-2010. Six missile carriers were planned. Design of the new SSBN began in 1982. The new project continued the targeted development of the ship's entire systems. Seven teams of scientists, designers, and engineers worked to develop the most effective technical solutions. The ship and its systems were designed for the new M5 SLBM, which had been developed in parallel with the carrier since 1980.
The collapse of the USSR and the subsequent easing of international tensions, as well as delays in missile development, forced adjustments to the submarine series' construction. The order was limited to four submarines. Due to the unavailability of the new missile, the first Triumphan-class SSBNs had to be equipped with the M45 SLBM, essentially a major upgrade of the M4 missile.
It was equipped with a TN-75 warhead with six independently targetable warheads (MIRVs) with a yield of 100 kt each and a firing range of up to 5300 km.
Taking the Trident II SLBM as a reference, French designers based the new M5 on the same weight and dimensions, which influenced the dimensions of the new missile's launch vehicle. This explains the slight difference in the design and hull dimensions between the Triomphant-class SSBN and the American Ohio-class SSBN. (For example, the Triomphant's hull diameter is only 31 mm smaller than that of the Ohio.)
Triumphant
Some tactical and technical characteristics:
- Main dimensions: length – 138 m; width – 12,5 m; draft – 10,6 m
- Displacement: surface -- 12,640 tons; underwater -- 14,335 tons
- Speed: surface – 12 knots; underwater – 25 knots
- Diving depth: working – 380 (250-350) m; maximum – 487,5 m
- Propulsion plant: nuclear power plant - K15 water-cooled reciprocating turbine with a thermal capacity of 150 MW; propulsion motor with a capacity of 41,500 hp, auxiliary diesel engines with a capacity of 1225 hp; one propeller shaft, fixed-pitch propeller in a jet nozzle
- Armament:
missile: 16 silos for M51 type SLBMs; 8 Exocet SM39 cruise missiles launched from torpedo tubes
torpedo: 4 bow 533 mm TA (ammunition - 10 torpedoes L5 mod. 3 and F17)
- Autonomy: 90 days.
The designers based the combat qualities of the new SSBN on the military's requirement to ensure its low visibility, maximum quietness, and stealth.
Understanding that the main source of noise on submarines is the power and propulsion systems, their improvement was given priority attention.
By the time the Triomphant was laid down, the shipbuilders had a K-15 nuclear VVR, which had proven itself on the previous generation of missile carriers. The same nuclear reactor was installed on the Charles de Gaulle missile carrier.
The K-15 VVR featured natural circulation of the primary coolant, eliminating the need for a primary circuit centrifugal pump. This significantly reduced the noise level of the steam generator and increased its operational reliability. The steam generators were housed in the reactor core and formed a single unit with the reactor vessel. This made the reactor more compact.
The modular steam turbine unit (STU) had two independent turbogenerators (ATGs) with their own condensers. The generators were mounted on a single shock-absorbing platform. This reduced noise and vibration from the units. Noise and vibration-isolating plates made of rubber or polymers were used to isolate residual noise.
A low-speed, low-noise fixed-pitch propeller is housed in a guide nozzle that shields propeller noise.
To reduce hydrodynamic noise, the hull contours were computer-modeled to maintain the laminar flow around the hull and protruding parts of the ship. The contours of the missile bank and the enclosures for the retractable devices were modified. The forward hydroplanes were raised to the upper edge of the oval control surface. The bow is now elliptical rather than stem-shaped.
In a number of systems, rolling bearings were replaced with plain bearings. This resulted in a noise reduction of half that of the Redoutable-class SSBNs.
The use of a new grade of 100 HLES steel with a yield strength of up to 1000 MPa allowed the Triumphan's operational diving depth to be increased to 380 m, which also improved stealth and increased the submarine's maximum quiet speed to 20 knots.
As a result, the implementation of measures to reduce the acoustic signature of the Triomphant SSBN made it possible to build a submarine that is quieter than the American Ohio-class, previously considered the quietest SSN in the world.
SSBN "Triumfan"
Triomphan-class SSBNs have a single-hull design with a streamlined hull and missile berth (superstructure). The submarine's missile compartment, rather than the control center, was used as the submarine's center of gravity. The distance between the missile silos, located in two missile sections, was increased. Between the sections, stations housing the missile control system instruments and auxiliary mechanisms were placed. This design was used only on Triomphan-class SSBNs.
Design features
Structurally, the submarine is divided into four compartments, with spherical bulkheads within each compartment. This is unique in modern shipbuilding.
The submarine's pressure hull is cylindrical (with a main diameter of 12,5 meters), with elliptical truncated cones at the ends. The ends are topped with torispherical bulkheads of relatively small diameter.
The forward compartment houses the anti-ship missile and torpedo armament, the central post with combat posts and radio-television equipment, as well as the crew quarters and cabins.
The second compartment contains the SLBM silos. They are arranged in two sections, with the missile control system's combat stations and auxiliary mechanisms located between them.
The third compartment contains the reactor and the steam generating unit (SPU).
The fourth compartment contains a steam turbine unit (STU), two ATGs and a hydroelectric motor on a shaft line with a drive to a water jet propulsion unit.
The central gastrointestinal tract is located in the permeable extremities (bow and stern).
The bow of the hull contains a thruster.
Four 553 mm TA are welded into the bow bulkhead symmetrically to the longitudinal axis and at an angle to the centerline of the ship.
The main spherical antenna of the sonar system (DUUX-80) is located in the extended nose section, well removed from the pressure hull. Isolating screens are also installed here to create favorable operating conditions for the sonar system. The nose antenna fairing is made of fiberglass-reinforced plastic.
The stern end ends with a cruciform tail with depth and direction rudders, and a Pump-Jet type water jet propulsion unit.
The horizontal stabilizers are equipped with chucks at the ends. The vertical rudder blade is insulated. The British used the same design on their future Dreadnought-class SSBN.
The second, no less significant task that the SSBN creators had to solve was to achieve an advantage in the detection range of enemy anti-submarine forces by the submarine's hydroacoustic means before they detected the missile carrier.
The Triomphant became the first French submarine to be equipped with a fully-fledged sonar system (SAS), which significantly increased the crew's situational awareness and the submarine's combat capabilities.
The missile carriers are equipped with the DMUX-80 sonar system, which includes:
- active-passive GAS DUUV 23 (nose spherical antenna);
- DUUX-5 GAS with six on-board antennas;
- LF passive (noise direction-finding) GAS DSUV-62 with a flexible extended towed antenna 100 m long and 10 cm in diameter;
- GAS DMUX-33 -- reconnaissance station and detection of hydroacoustic signals (working GAS of surface ships/submarines and homing heads of anti-submarine torpedoes).
The last missile carrier was equipped with a UMS-300 sonar system from the Thales company.
The boat's own noise level was recorded by the noise monitoring system of the boat (QSUA-A), consisting of approximately 40 hydrophone sensors and accelerometers.
The press has noted that the new sonar system can detect the Virginia-class stealth submarine at a range of up to 50 km, whereas the typical detection range for such submarines is no more than 10 km. However, this claim is questionable due to the submerged collision between the SSBN Triomphant and the British SSBN Vanguard, which occurred in the Atlantic on the night of February 4, 2009.
During the collision, the Vanguard sustained damage to the hull near the starboard missile compartment, with noticeable dents and scratches appearing on the hull. The submarine surfaced at the observation point and was towed to its base in Scotland. The Triumphan damaged the lower segment of its sonar dome under the bow. However, it managed to submerge and reach the Brest naval base under its own power.
The Triumphan-class missile carriers have a single ship-wide information system that combines all data on the ship's condition, its systems and weapons, as well as the external situation.
The submarine is equipped with a SYCOBS (Systeme de Combat pour Barracuda et SSBN) combat information and control system. It provides combat data to the automatic combat control system (ACCS), the core of which is the SET (System d'Exploitation Tactique) tactical system. Here, the data is processed and displayed in the most informative form on situational awareness displays, as well as transmitted to the ship's commander in the form of visual and audible signals, voice messages, and recommendations.
The wheelhouse contains an antenna post with a TV camera and an IR station, a navigation (NVTs detection) radar DRUA-33 and a set of tools EW ARUR-13 (as part of the DR-4000U and DR-3000U stations from Thales).
The submarine is equipped with a comprehensive communications system, including a satellite system (Syracuse II), and has several types of antennas (buoy, loop, whip, and loop). It also has periscopes: a SFIM L commander's periscope and an MRA-2 anti-aircraft periscope.
All French SSBNs are based at Ile Longue, near Brest, in a permanent base built specifically for them. All routine maintenance and repairs are also carried out here. Also located near the piers are a missile storage facility, assembly workshops, and workshops for preparing them for combat use.
The command of the strategic ocean forces of the fleet is constantly working to equip SSBNs with the latest weapons.
Thus, on October 28, 2025, the Naval News publication informed its readers:
The French submarine-launched ballistic missile M51.3 has entered service.
In other words, it has been accepted into service. It was also reported that the M51.3 has a range of 6000 miles and a speed of Mach 25. It is capable of carrying 6-10 TNO-2 warheads with a yield of 100 kilotons each. It also boasts enhanced accuracy and the ability to penetrate enemy missile defense systems.
The high combat performance of French SSBNs has earned the highest praise from military experts. Many of the technical solutions used in their construction have been adopted by shipbuilders from the world's leading naval powers.
What is planned to replace the Triumfans?
The SNLE 3G (Sous-Marin Nuclear Power Plant) project, a third-generation SSBN, is being developed to replace the Triomphant-class SSBNs. The program is being implemented under the direction of the French Ministry of the Armed Forces' Directorate General of Armaments (DGA), with the participation of Naval Group (design and construction) and Technic Atome (nuclear reactor development and supply). It was reported that the submarine will be equipped with a new K22 nuclear reactor with a thermal capacity of 220 MW.
This is a highly labor-intensive project. French experts estimate that the design phase consumed approximately 15 million man-hours, and the construction of each submarine will require at least 20 million man-hours. Over the next 30 years, the program will consume up to 100 million hours of work, including the design and construction of infrastructure facilities and the ships themselves.
As of 2021, observers estimated the cost of the SNLE 3G program at approximately €40 billion. However, the French Ministry of the Armed Forces stated that it was too early to provide a precise estimate at that time. The supply chain alone will involve approximately 200 companies and 3000 people. The main contractor is Naval Group, which is collaborating with Technic Atome.
Key Features of SNLE 3G
- Main dimensions: length – 150 m; width – 13 m; draft – 11 m
- Displacement: surface – (n/d); underwater – 15,000 t
- Speed: surface – 12 knots; underwater – 25 knots
- Diving depth: working – 400 (380) m; maximum – about 480 m
- Power plant: nuclear power plant – PWR type K 22 with a thermal capacity of 220 MW; propulsion motor, auxiliary power plant, one propeller shaft, water jet propulsion unit
- Armament:
missile: 16 silos for M51.3/M51.4 SLBMs (6-10 TNO-2 warheads each with a yield of 100 kt); 8 Exocet SM39/Naval-Scalp cruise missiles launched from torpedo tubes;
torpedo: 4 bow 533-mm TA (ammunition - 10 F21 torpedoes)
In the future, it may be equipped with future cruise and anti-ship missiles (FCASW).
- Crew: about 100 people
- Autonomy: up to 100 days.
Other features include improved acoustic and magnetic shielding to reduce signature, enhanced enemy detection capabilities through high-tech sensors, improved hydrodynamics and maneuverability.
It is also planned to use an X-shaped stern empennage and a water jet propulsion system, as on the Suffren-class submarines.
On March 20, 2024, the first steel cutting ceremony for the lead submarine's pressure hull took place at the Naval Group shipyard in Cherbourg.
Assembly of sections of the first third-generation SSBN was planned to begin in late 2026 – early 2027, and launching to take place in the early 2030s.
The lead SSBN is scheduled to enter service no earlier than 2035. Subsequent submarines are to be delivered at five-year intervals. The final, fourth submarine, is scheduled to be commissioned in 2050.
A total of four submarines are planned for construction—the same number as the Triomphan class. The replacement of the existing SSBNs is scheduled to begin between 2035 and the 2050s. Meanwhile, the remaining Triomphans will undergo modernization, incorporating selected technologies developed for the SNLE 3G. This will allow new technical solutions and weapons to be tested in naval conditions, not just on the test rigs and ranges of the manufacturers.
The new submarine's specifications have not been officially disclosed. However, Naval News claims that its design will be similar to the Triomphant-class SSNs, but the SNLE-3G will be larger: its hull length will be approximately 150 meters, almost 10 meters longer than the current strategic submarines, and its submerged displacement will exceed 15 tons. The crew will number 110. Each submarine will be capable of carrying 16 SLBMs. The submarines will be equipped with four torpedo tubes with a total of 18 anti-ship missiles and torpedo tubes.
Achieving maximum stealth for missile carriers and ensuring their advantage in detection range remain the primary objectives, as the main condition for victory in a duel with enemy anti-submarine forces.
The new sonar system for the SNLE 3G is being developed by Thales Group under a 42-month contract awarded by the military in 2012. The sonar system incorporates a powerful digital-based signal processor and new algorithms for processing data received from the next-generation onboard and forward-facing sonars, as well as from the towed linear array (ALRO) antenna, which uses optical technology.
Some features of the new HAC for SNLE 3G
It is known that the bow of the submarine is completely dedicated to the hydroacoustic dome, which implies the use of a very large conformal hydroacoustic array in the bow of the SSBN.
The aft section is designed to accommodate a center section for the towed system, which has been under development since 2016. Between the upper rudders of the X-shaped tail, there is a small vertical fin used for deploying and retrieving the flexible, extended towed ALRO sonar antenna. Its parameters will remain the same: length – 100 m, diameter – 10 cm.
The ALICIA system, designed for comprehensive analysis, localization, identification, classification, and notification of detected targets, will be mounted along the ship's sides. It optimizes operator workload and assists in decision-making. Artificial intelligence systems are expected to be used to process the large volume of information.
The possibility of the future sonar system to detect and classify low-frequency hydroacoustic signals ULF (Ultra-Low Frequency) with a frequency of 0,3–3,0 kHz is also noted.
The new sonar system is expected to be deployed gradually. The first units and versions of the systems will be installed on second-generation SSBNs (SNLE 2G) starting in 2025. They will be installed on third-generation submarines (SNLE 3G) during their construction, having already undergone testing and refinement on operational submarines. Thus, by 2035, the plan is to have a sonar system free of any "teething problems."
To reduce its visibility, the SSBN hull will be completely lined with anechoic tiles, which are designed to absorb the locating pulses of active sonars, as well as dampen the lower sounds emitted by the submarine itself.
It is expected that with the implementation of all the innovations, the noise level of the French third-generation SSBNs will be lower than the noise level of the ocean.
It is impossible to achieve the stated combat characteristics without implementing the latest advances in electronics, control systems, and artificial intelligence systems.
According to Naval Group, the ship's integrated control system includes approximately 100,000 high-tech electronic devices, as well as hundreds of cables and circuits using fiber optic technology. The ship's integrated control system is expected to be AI-based.
The SSBN basing, logistics, and combat support systems are well-established and do not require significant changes. Like their predecessors, the third-generation missile submarines will be based on the Ile Long Peninsula.
They will conduct combat patrols primarily in the North Atlantic to minimize the risk of detection. These patrols will last two to three months.
The SSBN deployment system involves their rotation: one boat on combat patrol, the second at sea practicing combat training tasks or in a state of short-term readiness for deployment, and the other two undergoing technical maintenance.
The new submarines are expected to form the core of the Fifth Republic's strategic nuclear deterrent forces and remain in service until 2080-2090. Given the current Élysée Palace administration's course of confrontation with the Russian Federation, these SSBNs could pose a real threat to the national interests and security of our country and the Union State of Belarus and Russia in the future. This will require additional efforts to mitigate the threats posed by French missile-carrying submarines and the implementation of an effective system to counter threats emanating from the ocean depths.
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