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Monday, 24 June 2013 09:39
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Focus - Naval Technology

 
 
 
A3SM: A True Game Changer for Submarine Self Defence against Threats from the Sky
 
Text and interview by Xavier Vavasseur

As part of the Paris Air Show Navy Recognition was invited by DCNS to visit their factory located near Angoulême in southwestern France. The 260 year old site used to manufacture guns for the "French Royal Navy". It now specializes in the production of submarine equipment such as torpedo tubes and torpedo handling systems. It is also the place where the FREMM frigates' vertical launch systems are produced. The focus of the visit however was the A3SM, a new anti-air defence weapon system for submarine currently under development by DCNS and MBDA.
     
Representatives from both DCNS and MBDA gave us exclusive details on the A3SM project during our visit of the DCNS factory in Ruelle near Angoulême, southwestern France.
     
A3SM stands for Arme Anti-Aérienne pour Sous Marins (literally Anti-Air Weapon for Submarines). The project was first unveiled during Euronaval 2012 and it actually consists in two versions: a Mast version and an Underwater Vehicle version.

A3SM: What needs does it fulfill?
Today, submarines have no way to defend themselves against air threats. Submarine forces worldwide have an increasing need to operate close to shores in shallow waters. (As an example during the campaign in Libya, submarines were conducting intelligence missions close to shores). In such situation submarines are an easy target for helicopters and maritime patrol aircraft (MPA). When detected in shallow waters, there is no possibility for the submarine to escape, contrary to deep sea where they can employ various tactics and disappear. Up until now, submarines were harmless against air threats, while significantly cheaper and less complex naval platform like small Fast Attack Craft (FAC) may be fitted with a SAM solution.

It is this gap that DCNS and MBDA are looking to fill. The doctrine of use is not for the submarine to attack first. The submarine will keep trying to escape when faced with an air threat as it has always been the case. However the submarine will shoot it down if escape is not possible.

This fast reaction scenario leaves little time to react therefore calls for ready to fire, fire and forget weapons at all time.
     
A3SM weapon systems may be fitted on the full range of DCNS Submarines
A3SM weapon systems may be fitted on the full range of DCNS Submarines
     
A3SM: How does it work?
For target designation, the submarine crew needs some of the following data from the target: its bearing, its range, its speed or its course. When submerged the crew will use acoustic detection to acquire this data. If faced with a helicopter with dipping sonar, the crew will get its bearing, its speed (virtually 0) and its approximate altitude which is enough aquire the target with accuracy. If faced with an MPA, the crew will know a threat is in the area. If the submarine is detected it will employ tactics to go to periscope depth and acquire the MPA with its optronics systems.

This is all consistent with current submarine missions: When a helicopter dips its sonar, its behavior is considered aggressive by the submarine. Same thing when a MPA detects the submarine thanks to its active sonobuoys.

DCNS offers two solutions to give the choice to its customers. The mast version has shorter range but doesn't impact the maximum payload of the submarine. It is the suggested choice for smaller platforms such as the Andrasta which has provision for only 6 weapons. The mast version would actually increase the payload of Andrasta.
     
The underwater vehicle version comprises a torpedo-like capsule (the VSM) containing a medium-range (20 km) Mica missile that is tube-launchable at any depth. The capsule is similar to the type developed for submarine-launched SM 39 Exocet anti-ship missiles, a proven system which exists for 35 years now. The missile is based on VL Mica (launched from surface vessels) which has already been procured by several navies.
A3SM Underwater Vehicle Version with Mica IR
Image: MBDA/DCNS
     
A3SM Underwater Vehicle Version:
The underwater vehicle version comprises a torpedo-like capsule (the VSM) containing a medium-range (20 km) Mica missile that is tube-launchable at any depth. The capsule is similar to the type developed for submarine-launched SM 39 Exocet anti-ship missiles, a proven system which exists for 35 years now. The missile is based on VL Mica (launched from surface vessels) which has already been procured by several navies. MICA covers Beyond Visual Range situations offering additionally 2 guidance systems with its 2 interoperable seekers:
• RF MICA with radar seeker providing all weather shoot-up / shoot down capability
• IR MICA with dual waveband imaging infrared seeker
VL Mica has a range of up to 20 Km and reaches speeds in excess of Mach 3. A3SM underwater vehicle version with Mica missile can be considered a medium range solution to be deployed when submerged.

For submarine launch, MBDA selected the IR version because of the characteristics of the threats: Helicopters and MPAs have low Doppler signature and IR is a better match against these types of targets. The 12 Kg warhead of the Mica guarantees a "full kill" capability against both types. Fitted with thrust vectoring, Mica has very high maneuverability (proven against anti-ship missiles) which leaves little to no escape opportunities for slow moving targets such as ASW helicopters and MPAs. The thrust vectoring of Mica allows it to be fired when the submarine is cruising away from the threat. In addition the VSM (torpedo-like capsule holding the Mica) is powered by a rocket engine and has the ability to maneuver underwater, meaning the Mica may attack its target from any angles and catch the helicopter or MPA crew off guard.

The VSM was adapted to provide the same launch environment as when a VL Mica is launched from a vertical launch system. All the other steps (launch from the submarine, underwater step, breach of the surface and air step) remain exactly the same as for the SM39 therefore are already validated. MBDA basically merged 2 existing concepts into a single one: SM39 + VL Mica. The only modifications are found inside the VSM. Some adaptation work was conducted to fir the Mica which is a smaller missile than Exocet. The other focus is behavior at the launch: Mica accelerates very quickly therefore exhaust gas management is different.
     
The mast version comprises a missile housing (that remains watertight throughout the submarine’s operating range and down to maximum diving depth) mounted on a hoistable mast and containing three short-range MBDA Mistral 2 missiles that can be fired from periscope depth. DCNS is in charge of developing the launching system. Mistral 2 is a lightweight, fully digital, heat seeking missile with a maximum range of 6.5 Km and maximum speed of Mach 2.5. An Infra-Red camera from SAGEM is fitted in the missile housing to act as optronic aiming sight. A3SM Mast version with Mistral missile can be considered a short range solution to be deployed from periscope depth.
A3SM mast version comes with a missile housing containing 3 Mistral missiles and an IR camera
     
A3SM Mast Version:
The mast version comprises a missile housing (that remains watertight throughout the submarine’s operating range and down to maximum diving depth) mounted on a hoistable mast and containing three short-range MBDA Mistral 2 missiles that can be fired from periscope depth. DCNS is in charge of developing the launching system. Mistral 2 is a lightweight, fully digital, heat seeking missile with a maximum range of 6.5 Km and maximum speed of Mach 2.5. An Infra-Red camera from SAGEM is fitted in the missile housing to act as optronic aiming sight. A3SM Mast version with Mistral missile can be considered a short range solution to be deployed from periscope depth.

Contrary to Mica missile, the Mistral requires to be locked on target before launch. The Mistral's homing guidance with an infra-red seeker is reported to be the best solution against helicopters and MPAs. A3SM mast version may shoot on the move and in any directions which is an important feature as reaction time is key for self defence. Thanks to its compact nature (less than 20 Kg, less than 2 meters) three Mistrals can be fitted in the mast. When back in port, the whole canister may be replaced by a new one. Loading of the Mistrals in the canister occur in a dedicated facility.

Mistral is fitted on most vessels of the French Navy, from the aircraft carrier to patrol boats. It has shown its capability against many types of targets: anti-ship missiles, helicopters and fast jets. MBDA has extensive experience integrating the Mistral on many platform and launchers (fixed, vehicles, helicopters, ships...) and see no difference in integrating the Mistral to the DCNS launcher. DCNS goal with the existing mast prototype is to qualify the movement of the canister

A3SM: A Game changer
DCNS and MBDA insist there is no missile development required as both missiles are already proven solution, which significantly reduces risk and cost. Both versions will be fully integrated with Subtics combat systems.

DCNS and MBDA already submitted offers to several potential customers and stand ready to finalize the development once they get a contract. They estimate it could take as little as 2 to 3 years between contract signature and IOC.

A3SM weapon systems for submarines can be considered a game changer because the rules of anti--submarine warfare are indeed about to change. While submarines will certainly not start conducting anti--helicopter or anti-MPAs patrols, they will soon have means to take action and defend themselves in case of absolute necessity while in the past ASW helicopters and MPAs could keep on engaging a detected submarine over and over again without fear of retaliation. A3SM will act as deterrence for submarines and keep ASW helicopters and MPAs at bay in the near future.
     
 
As part of the Paris Air Show Navy Recognition was invited by DCNS to visit their factory located near Angoulême in southwestern France. The site specializes in the production of submarine equipment such as torpedo tubes and torpedo handling systems. It is also the place where the FREMM frigates' vertical launch systems are produced. The focus of the visit however was the A3SM, a new anti-air defence weapon system for submarine currently under development by DCNS and MBDA.
 
------------------------- FLASH NEWS -------------------------
NAVAIR awarded a $3.643 billion multi-year procurement contract to Northrop Grumman Corp. on June 30 for 25 E-2D Advanced Hawkeye aircraft. NAVAIR awarded a $3.643 billion multi-year procurement contract to Northrop Grumman Corp. on June 30 for 25 E-2D Advanced Hawkeye aircraft.
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