A proposal to introduce a multi-role 35mm gun system into the RAN could broaden capabilities and provide potential commonality with the ground-based air defence requirement being sought under Project Land 19 Phase 7B.
Julian Kerr | Sydney
This would, however, require a major change to the status quo, and the acceptance by Navy of the benefits to be derived from a sophisticated gun system in a calibre with which it is not familiar in the Australian environment.
Current RAN smaller-calibre weaponry is a mixed bag; 30mm cannon on the Huon class minehunters, 25mm cannon on the Canberra class Landing Helicopter Docks and Armidale class patrol craft, 12.7mm machineguns on the LHDs, Anzac class frigates and Armidales, and the 20mm Phalanx close-in weapon system (CIWS) on the three remaining Adelaide class frigates.
Phalanx deployment from existing inventory, upgraded to the latest Block 1B Baseline 2 configuration, is set to increase. One mount will be installed on each of the three Hobart class air warfare destroyers, three on each of the LHDs, one on the Landing Ship Dock HMAS Choules, and one each on the two auxiliary oiler and replenishment vessels now under construction in Spain.
Two additional mounts are to be procured at a later date to inform the self-defence capability requirements for the nine Future Frigates to be constructed under Project Sea 5000.
Nevertheless Rheinmetall Defence believes its 35mm Millennium Gun and its cutting-edge technology is well-suited to provide a broader and more effective combined anti-surface and anti-air defensive capability both to the 12 Offshore Patrol Vessels (OPV) to be acquired under Project Sea 1180, and to the Future Frigates.
As such the company – which describes the Millennium Gun as the world’s most advanced medium-calibre naval gun system – confirms it has been in discussion with the three contenders for each project, with Defence’s Capability and Sustainment Group (CASG), and with Navy.
(Right) RAN sailor LSET Stephanie Horswood maintains the Phalanx CIWS while deployed aboard guided missile frigate HMAS Melbourne. Credit: Defence
Under the normal Comparative Evaluation Process (CEP), Defence sets functional requirements and in the case of Sea 1180 this is thought to include a gun of between 30-40mm calibre, for which each tenderer offers a range of solutions.
According to Rheinmetall, the Millennium Gun meets and exceeds the requirements for the OPV, particularly in the littoral environment. It also offers advanced capability for an inner-layer close-in weapon system for Future Frigate as well as potential self-defence upgrades for other platforms.
In an anti-surface role, the Millennium Gun using programmable ammunition meets US Navy requirements for countering a multi-axis threat from multiple, fast-inshore attack craft, the company states. Using high explosive rounds, it also satisfies the requirements for the constabulary function.
In an anti-air role, the gun can engage the entire spectrum of air threats, ranging from low-radar cross section anti-ship missiles to fast-attack aircraft and helicopters. Additionally, the company says, it can easily defeat challenging low, slow and small threats posed by unmanned aerial vehicles, and can also provide Counter-Rocket and Mortar (C-RAM) defence in harbour.
Essentially, the anti-air capabilities claimed in the maritime role reflect the likely requirements for Land 19 Phase 7B, albeit as part of a multi-gun system. If necessary, the non-penetrating ISO mount configuration allows a gun to be removed from its host ship and deployed as part of a ground-based air defence system in an asset protection role such as harbour defence.
An on-mount ballistics and fire control computer enables the Millennium Gun to be set up to receive track data from any current or future electro-optical or radar tracking sensor, allowing the gun to be controlled from a basic remote-control weapon station.
Using this raw data, the computer calculates the optimum aim point for highest hit probability out to an effective range of about 5,000 metres, utilising the gun’s 1,000 rounds-per-minute rate of fire and Rheinmetall Ahead programmable airburst ammunition.
The initial muzzle velocity of each round is measured after firing but prior to leaving the barrel. This information is fed back into the gun’s data processing system prior to programming the round, thus adding realtime muzzle velocity compensation to the ballistic computation, ensuring accurate time of flight to the aim point.
During a two-microsecond programming window which opens at the exit of the barrel, time of flight data is then transferred inductively to the fuse, after which the round can not be jammed or the programmed time of flight disrupted.
A short burst of Ahead rounds produces a dense cloud of tungsten spin-stabilised, hard-edged cylindrical sub-projectiles which are released in an 11-degree cone focussed on the target’s trajectory. Ahead rounds can also be fired in non-fused mode, in which they behave like frangible rounds on impact and are able to penetrate and destroy hard targets.
“This might be overkill for a UAV at relatively short ranges but if the next thing thrown at you is a multimillion dollar high speed shipkilling standoff weapon, you’ve still got a single weapon system that can deal with that threat,” Tim Pickford, general manager Business Development for Rheinmetall Defence Australia said to ADM.
“So the first benefit is mission flexibility, using the same weapon and the same calibre and providing more operational options to government, particularly with the OPVs.
“Secondly, commonality can solve a multiple of logistics problems – you’ve got common carrier and cartridge systems with different warheads or applicators that can be tailored for individual threats, common application handling systems, and common storage requirements.
“And when you start to invest significantly in a single capability or single calibre you can start to work in detail with the Original Equipment Manufacturer to optimise that capability for a very wide set of tactical applications.”
Adrian Smith, managing director of Adelaide-based Rheinmetall Electronics, sees the Millennium Gun as a likely contender to replace the Phalanx CIWS in Australia and elsewhere.
“Phalanx was great in its time and it’s an easy option, but it lacks multi-mission capability against the spectrum of modern threats,” he said.
“It activates at a low range which was perfect for a sub-sonic threat which was what it was designed for, but it’s quite scary taking on a modern, agile, high-speed threat at that sort of range (ED: Phalanx’s effective range is classified, but is widely reported as being around 1,500 metres).
“The calibre doesn’t produce enough kinetic energy, and it’s not an option for upgrading.”
The gun mount also has the potential to incorporate a high-energy laser capability that has been demonstrated successfully at sea and on land
Comparing the 35mm Millennium Gun to the multirole 40mm Bofors 40 Mk 4 naval gun, Smith said the 35mm system had more than three times the rate of fire, an on-mount magazine with two and a half times the combined capacity of the Bofors on-mount and intermediate magazine, and Ahead round sub-munitions with more than 18 times the kinetic energy of those in Bofors programmable 3P ammunition.
A future development plan for the Millennium Gun includes its own organic search, track and fire control radar capability. The gun mount also has the potential to incorporate a high-energy laser capability that has been demonstrated successfully at sea and on land, Smith noted.
The Millenium Gun is in service on two classes of ships in the Royal Danish Navy. It has also been supplied to Navantia for a number of international customers.
Damen are presently finalising the delivery of Sigma-class frigates for the Indonesian Navy, each of which includes a Millennium Gun. The gun is also the effector in the German Army’s C-RAM MANTIS (Modular Automatic and Network Capable Targeting and Interception System).
This article first appeared in the March 2017 edition of ADM.