Modernization of French Strategic Oceanic Force: Le Triomphant SSBN Now Fitted with M51 SLBM

Focus - Le Triomphant SSBN
Modernization of French Strategic Oceanic Force: Le Triomphant SSBN Now Fitted with M51 SLBM
On August 4, 2015, the French Navy (Marine Nationale) took over full responsibility and the effective command of ballistic missile submarine (SSBN) Le Triomphant (S616). This transfer of responsibility is an important milestone following the refit period started in May 2013 for maintenance, repairs, modernization and adaptation to the M51 new generation submarine launched ballistic missile (SLMB). Le Triomphant will now start some trials at sea before returning in the operational cycle.
An NH90 NFH Caiman transfers personnel on board French Navy Le Triomphant class SSBN.
An NH90 NFH Caiman transfers personnel on board French Navy Le Triomphant class SSBN.
Picture: V.Guyoton © Marine Nationale
Le Triomphant, head of the class commissioned in 1997, returned to the French Navy SSBN base of L'île Longue on April 14, 2015, following 20 months of work at the DCNS shipyard in Brest naval base. Work focused on the upgrade of the missile launch system. The SSBN is switching from the M45 SLBM to the new generation M51 SLBM. The submarine was also fitted with the new SYCOBS tactical combat system (a new combat management system common to Barracuda class SSN and the Le Triomphant class) and an overall more efficient navigation system (SGN-3E). Le Triomphant will also be able to deploy the F21 new generation heavyweight torpedo for self defense once procured by the French Navy. Finally, this periodic downtime was an important step for the Le Triomphant since this was her mid-life refit.

Collision with HMS Vanguard
In February 2009, Le Triomphant and Royal Navy SSBN HMS Vanguard "came into contact briefly" while underway underwater in the Gulf of Gascogne. The two SSBNs were damaged in the accident, but none reported damage to their nuclear facilities. The French and Royal Navy never elaborated on the exten of the damages but Le Triomphant would have bumped the side of the HMS Vanguard and would have ripped and slid the flank of the British SSBN. Both submarines joined their respective bases of L'île Longue and Faslane under escort. Le Triomphant was placed in dry dock to determine the extent of damage to the sonar dome, kiosk and dive bars. If anything this incident illustrates the extreme stealth of both classes of SSBNs. The US Navy, Marine Nationale and Royal Navy do not share the patrol areas of their SSBNs.
French New Generation SLBM M51. Picture: French MoD
French New Generation SLBM M51. Picture: French MoD
The M51 is the new generation intercontinental SLBM gradually replacing the M45 since 2010. Each missile carries six to ten independently targetable (MIRV or Multiple Independently targeted Reentry Vehicle) TN 75 thermonuclear warheads. TN 75 will be replaced with the new Tête nucléaire océanique (TNO or oceanic nuclear warhead) warheads starting this year (2015). These new warheads are reported to be maneuverable (MARV or Maneuverable Re-entry Vehicle) in order to avoid potential ballistic defenses. The TNO has a yield that is estimated to be greater than or equal to the yield of the TN 75 warhead, 150 kilotons of TNT (kt) with a CEP (circular error probability) of 150 meters. The warhead's design and functionality were validated through simulation, particularly with DAM's Tera 100 supercomputer, Megajoule laser, and radiographic equipment.

The three-stage engine of the M51 is directly derived from the solid propellant boosters of the Ariane 5 space rocket. Open source data indicates an M51 weight of 52,000 kg, a length of 12.0 m and a diameter of 2.3 m. M51 operational range is reported to be 8,000 to 10,000 km with a speed of Mach 25.

The first test launch of an M51 ballistic missile was successfully carried out at Centre d'essais de lancement de missiles (CELM) in Biscarosse, France, on November 9, 2006. The sixth missile test carried out on May 5, 2013, ended in failure.
Le Triomphant SSBN during refit at the DCNS submarine shipyard in Cherbourg.
Le Triomphant SSBN during refit at the DCNS shipyard in Brest naval base.
Le Triomphant is the second SSBN of the French Navy to be upgraded for M51 during the so-called "adaptation" refit. Le Vigilant (S618) , third ship of the class, had undergone the same transformation between 2010 and 2013. The next and last SSBN to benefit from this overhaul will be the Le Téméraire (S617) in 2016. Following this last refit, all four Le Triomphant class SSBNs will deploy the new M51 SLBM:
Le Terrible (S619), last ship of the class which was commissioned in 2010, was fitted with M51 capability from its construction.

These "adaptation" refits have no impact on the permanence at the sea of the strategic oceanic force (FOST) which is the backbone of the French deterrence strategy. The SSBNs refits are, however, an important step to modernize the FOST as part of the "Coelacanth program" and are necessary to ensure the credibility of the French deterrence.

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