The Martlet missile – the Wildcat helicopter gets its claws

In May 2020 the first successful firings of the Martlet (Lightweight Multi-role Missile) were made from a Wildcat helicopter. Are we look at the development of this weapon and the new airborne anti-surface capability this will give the Royal Navy.

Background

In response to the growing threat from manned and unmanned small craft swarms, especially in the Arabian Gulf, the RN issued a requirement for the Future Anti Surface Guided Weapon(Light) (FASGW(L)) in 2008. This was part of the programme to replace the Sea Skua light anti-ship missile in service with the Lynx helicopter (1982-2017). The FASGW(H) (Heavy) requirement is being met by the Anglo-French Sea Venom missile manufactured by MBDA (which we will examine in a future article).

Thales first made their Lightweight Multi-role Missile concept public in 2007 and was well placed when it was selected to meet the FASGW(L) requirement. The LMM is based on the airframe of the Starburst MANPAD missile, formerly used by the British Army. Startreak has subsequently replaced Starbust in Army service and much of the technology of the newer missile has also been incorporated.


In April 2011 Thales was awarded an initial production contract by the MoD to develop a laser beam-riding version of the LMM. The initial test-firing demonstration took place in 2014 and a second £48 million contract was placed for the manufacture of 1,000 missiles. Thales’ Belfast plant produces the weapon which has sustained at least 60 jobs. Doubtless, many people have worked hard on the project but it will have taken over 10 years to get this relatively simple and already-developed weapon to the front line.

Despite its purchase primarily for airborne use, Martlet was first tested at sea by the RN mounted on a modified 30mm canon. In June 2019 a successful trial was carried out on board HMS Sutherland but to date, there has been no official confirmation about whether the shipboard mounts will go into operational service.

  • Conducting trials with the new weapon wings and inert missiles in order to test aircraft handling characteristics, Yeovil, December 2019 (Photo: ©Kevin Wills)

  • At least 3 Royal Navy Wildcats have been involved in the trials programme – tail numbers ZZ415, ZZ378 and ZZ513. (Photo: ©Kevin Wills)

  • December 2019 (Photo: ©Kevin Wills).

  • 2020 flight trials of the empty Weapon Wing. The wing is set at a high angle of attack so as to be most efficient during the slight nose-down attitude adopted by helicopters at high speed. (Photo: ©Mark Youd)

  • Full frontal with completed grey-painted weapon wing and live missiles ready for test-firing – May 2020.

  • The considerable wing area can be appreciated when viewed from the rear.

  • The leading edge of the weapons wing has been removed to access wiring. (Photo: ©Mark Youd)

The first live firing of the Martlet was conducted at the Manorbier Range in Pembrokeshire during ground trials in March 2019. Six telemetry rounds, fully integrated with the L3 Wescam laser guidance turret were fired, hitting simulated small boat targets at about 4.5Km.

Between 27th April and 21st May 2020, the first airborne trials were made at the MoD’s Aberporth Range off the Welsh coast. The DE&S’ Lightweight and Medium Attack Systems (LMAS) Team and Wildcat Delivery Team were able to conduct the trials despite being subject to COVID-19 restrictions. The firing was recorded by high-resolution cameras mounted on the Wildcat and chase aircraft for later analysis.

 

The first stage rocket motor burns for just 0.3 seconds with the efflux passing safely behind the aircraft. The missile is accelerated well clear of the aircraft before the second stage ignites. Unusually for a guided missile, it spins on its axis in flight.

Martlet is fired from a hermetically sealed pannier which can be stored for up to 15 years without maintenance. Being so light, it can be loaded by hand onto the Wildcat without specialist handling equipment. There is no launch recoil and the slim and aerodynamic body allows rapid acceleration to Mach 1.5 to reach small targets up to 8km away. The warhead consists of a dual-effect shaped charge and pre-fragmented blast warhead. One of three different fusing modes can be selected, depending on the target, either on impact, at a specific height or delayed action.

Martlet is guided using a semi-active control line of sight (SACLOS) laser beam riding. Before an engagement, the observer in the Wildcat places a laser pointer on the target using stabilised the EO camera and automatic target tracker (ATT). An Active Laser Generation Unit (ALGU) transmits a coded low-power beam from the Wescam MX-15Di turret on the nose of the Wildcat. Once launched, two receivers mounted on the missile’s tail detect the laser energy and maintain lock on the target. The system would appear to be only able to engage a single target at a time but each missile should eliminate a target within at seconds. Laser guidance is virtually immune from jamming and countermeasures. Martlet is a modular missile and could be fitted with an infrared seeker head module which would give a ‘fire and forget’ capability and increase the rate of firing. It is also possible swap out the warhead module for different kind of blast effects.


Theoretically, Martlet also has an air-air capability although avoid, rather than engage is usually the best policy for helicopters confronted with hostile aircraft. It can also potentially be used overland for ground suppression missions or to attack soft-skinned vehicles.

Martlet-Missile-Diagram-2

The weapon wing

Leonardo was awarded a £90M contract in 2014 to develop a weapon wing and then test and integrate both FASGW Light and Heavy missiles onto the Wildcat helicopter (which entered service in 2015). All 28 of the RN’s aircraft will be fitted with wiring and mounts, although the weapon wings can easily be removed when not required. It is unclear how many sets of wings will be supplied in total.

Leonardo published the first images of a basic non-aerodynamic weapon carrier design in early 2018 although it has subsequently been refined and considerably. The new aluminium and carbon-fibre composite wings generate up to 360kg of aerodynamic lift on each side of the helicopter in forward flight which helps reduce the additional drag and fuel requirement when carrying the weapons. Flight trials began on 2 July 2019 from Yeovil, initially in clean configuration and different speeds and altitude to determine effects on the aircraft’s performance.

The wing is considerably more aerodynamic than the ‘common weapon carrier’ fitted on the Lynx and has 4 hardpoints. This enables the Wildcat to carry either 20 Martlet (in four five-round panniers), 10 Martlets (in two five-round panniers) with 2 Sea Venom missiles or just 4 Sea Venoms. It remains to be seen whether the mixed armament will be carried operationally or ever be a justified tactical requirement. The attack profiles and intended targets for the weapons being very different. (The Lynx could carry a mix of Sea Skuas and Sting Ray torpedoes but this was never an operational requirement).

The Martlet lives up to its LMM name at just 13kg and a full set of 20 would be a load of around 260kg. The 120Kg Sea Venoms are a much heavier and would add 480Kg of weight if four are mounted. At high speed, the lift generated by the wing will more than offset the weight of the stores, reducing fuel use and stress on the rotor head. Inevitably the drag of external weapons will affect manoeuvrability, speed and range to some extent but Wildcat was designed from the outset with modern power-dense engines with margin for extra loads and ‘hot and high’ operating.

  • “Bruiser loose” – the first stage of the rocket motor has already fired very briefly, accelerating the missile away.

  • Stills from the ground-based test-firing conducted in March 2019. (Left) the front fins that steer the missile pop up from slots immediately after launch. (Right) The tail fins can be seen still fully folded as the missile emerges from the pannier.

  • The opposite angle.

  • Note the additional wiring for the 4 high-speed cameras fitted to the aircraft to record the launch.

  • The Wescam MX-15Di EO/IR turret on the Wildcat’s nose transmits a coded laser beam that guides the Martlet on to the target.

  • The mixed weapon load with heavier Sea Venom carried on the outer pylons. (Photo: Leonardo)

  • Initial flight test with dummy missiles in conventional anti-ship mode, carrying four Sea Venom (Photo: Leonardo)

  • Rotary wing aircraft are crucial to the protection of the future carrier strike group. This Leonardo image depicts the Wildcat on anti-surface duties while the Merlin provides ASW protection (Although it would be unlikely to use dipping sonar this close to the carrier!)

Tactical conundrums

When Martlet Initial Operating Capability is declared in 2021 there will still be much work to do. Sea Venom is due to enter service in early 2022 but Full Operating Capability for both elements of FASGW will not be until 2024. Development of standard operating procedures, tactical doctrine and full air and ground crew training with the new weapons will take another 3 years.

Martlet will give the RN much better capability, particularly against swarm attacks but as a new type of weapon in service, there are many questions to resolve. In high threat areas, a Martlet-armed Wildcat may be held at readiness on deck to respond to situations that could develop rapidly. For the frigates and destroyers, the embarked helicopter has a multitude of other tasks including surveillance, anti-submarine warfare and general transport duties. When the weapon wing is fitted there is no space for the pintle mount for the .50Cal M3M heavy machine gun which may be a more flexible and appropriate weapon in some circumstances. The Type 45 destroyers and Type 26 frigates will have hangar space for two Wildcats and it may make sense to have one Marlet/Sea Venom-equipped Wildcat ready for anti-surface duties backed by a second aircraft for other tasks. When operating with the Carrier Strike Group it will be interesting to see if Wildcats operate directly from the carriers or are carried by the escorts that form the defensive cordon around the carrier.

A fleet of small boats could behave apparently quite innocently, only switching to a mass attack at the last moment before a helicopter has time to get airborne. Iranian boats frequently harass or sail very close to coalition warships in the Gulf and despite being easy meat for Martlet or 30mm cannon, commanders are always working hard not to escalate this ‘grey zone’ conflict into a shooting war. While the helicopter has the advantage of speed, manoeuvrability, a good view and the ability to engage enemies at a much safer distance from the ship, the ship-mounted Martlet makes good sense as another layer of close defence. As a weapon primarily designed to counter asymmetric threats, the most challenging issue for the Martlet-armed Wildcat crew may be rules of engagement and the split-second decisions about whether to release weapons or not.