AW101 (EH101) Merlin |
|
---|---|
Royal Air Force Merlin HC3, 2008 | |
Role | ASW & medium-lift transport / Utility helicopter |
Manufacturer | AgustaWestland |
First flight | 9 October 1987 |
Introduction | 2000 |
Status | In production, in service |
Primary users | Royal Navy Royal Air Force Italian Navy Danish Air Force |
Produced | 1990s-present |
Unit cost | US$21 million (2009) |
Variants | AgustaWestland CH-149 Cormorant Lockheed Martin VH-71 Kestrel |
The AgustaWestland AW101, marketed as the EH101 prior to June 2007, is a medium-lift helicopter for military applications but also marketed for civil use. The helicopter was developed as a joint venture between Westland Helicopters in the UK and Agusta in Italy (now merged as AgustaWestland), primarily to replace the older Sikorsky Sea King in roles such as the medium-sized transport and anti-submarine warfare. The aircraft is manufactured at the AgustaWestland factories in Yeovil, England and Vergiate, Italy.
The AW-101 first flew in 9 October 1987, and entered service in 2000. It is currently in operation with various nations, such as Denmark, Italy, Japan, Portugal and the United Kingdom. Significant derivatives so far have been the Canadian AgustaWestland CH-149 Cormorant and the now-cancelled American Lockheed Martin VH-71 Kestrel. The name Merlin is used for aircraft in service with the British, Danish and Portuguese militaries.[1][2]
Contents |
In Spring 1977, the UK Ministry of Defence issued a requirement for an anti-submarine warfare (ASW) helicopter to replace the Royal Navy's Westland Sea Kings, which was becoming increasing inadequate in the face of Soviet submarine advances. In response to the launch of the Navy's Sea King Replacement iniative, Westland Helicopters put together a proposal, designated WG.34, for a three-engined helicopter of broadly similiar dimensions to the Sea King; the WG.34 was to feature a greater autonomy and range than its predercessor.[3] At the same time, Itay's navy, the Marina Militare, was also considering the replacement of its fleet of Sea Kings built by the Italian company Agusta; Westland and Agusta soon began talks regarding joint development of a successor helicopter.[4]
Agust and Westland finalised an agreement to work on the project together, and formed a jointly-owned new company, EH Industries Limited (EHI), to persue the development and marketing of the new helicopter to potential operators. On 12 June 1981, the UK government confirmed its participation in the project, allocated an initial budget of £20 million to develop nine pre-series examples.[5] A major agreement, which secured funding for the majority of the EH101's development program, was signed by both the British and Italian governments in 1984.[6] At the 1985 Paris Air Show at Le Bourget, Agusta showed a mock-up of a utility version of the new helicopter, leading to a more generalised design that could be customised to meet the needs of various civilian or military customers. On 9 October 1987, the first prototype helicopter took flight for the first time.[7]
In 1987, at a time where the EH101's future was not yet certain, as neither Britain or Italy had placed orders for production aircraft yet,[8] but the fledgling helicopter was to find itself at the center of a major political battle overseas. In Canada, the Conservative-led government was planning to acquire up to 43 EH101s to replace their current fleet of aging search and rescue and anti-submarine warfare helicopters.[9] The EH101's third engine and increased independence from naval platforms compared favourably to helicopters such as the Sikorsky Seahawk, and its additional range and de-icing capability were seen as vital for North Atlantic operations.[10]
With the end of the Cold War in 1991, Canada faced a reduced threat to its security, in light of which extensive military procurements such as the EH101 appeared excessive and unnecessary.[11] The issue began a topic of heated political debate over alledged costs of the procurement verses life extensions of existing Sikorsky CH-124 Sea King and Boeing Vertol CH-113 Labrador helicopters - such estimates widely fluctated in favour of either option.[12][13] Ultimately, the proposed acquisition was aborted by the new Liberal government in 1993.[14][15] The political arguements over the EH101 has been viewed as one of the major factors in the landslide 1993 electoral defeat of the Canadian government.[16]
In 1997, in light of the declining condition of its helicopter fleet, Canada launched the Canadian Search and Rescue Helicopter competition, which was won by the EH101, designated CH-149 Cormorant in Canadian service.[17] In 2004, the EH101 was entered into another Canadian competition to replace the Sea King fleet, however the Sikorsky CH-148 Cyclone was selected instead.[18]
Flight testing came to a halt following the crash of the second preproduction aircraft on 21 January 1993, testing resumed six months later. On 6 June 1993, the first EH101 outfitted with the Rolls-Royce/Turbomeca RTM322 turboshaft engine flew.[19] Also in 1993, it was revealed that the United States Marine Corps had conducted a study into the EH101 as a fallback option to the ambitious tiltrotor Bell-Boeing V-22 Osprey.[19]
In February 1995, Britain made its first order for the production EH101, ordering a total of 22 helicopters;[20] Italy also placed an order for 16 EH101s in October 1995.[21] In 1997, deliveries to the RAF of production EH101s began.[22] Westland and Agusta merged together to form AgustaWestland International Limited in July 2000.[23][24] Consiquently, the need for EHI to exist as a separate entity evaporated; in June 2007, the EH101 was re-branded as the AW101.[25]
In 2002, Westland made an unsolicited and unsuccessful offer to the MoD, proposing an enhanced variant of the Merlin intended to satify the UK's demand for additional lift capacity.[26] In 2005, a team of AgustaWestland and Lockheed Martin were selected as the winners of the US VXX competition to provide a replacement fleet to serve the President's Marine One helicopter.[27] The US presidential helicopter was designated VH-71 Kestrel, but the contract was eventually cancelled in June 2009 as opposition grew over signficant cost overruns.[28]
As of April 2009, more than 180 AW101s have been sold, which have accumulated a combined total of 170,000 flying hours.[29]
The AW101 Merlin follows a conventional design layout, but makes use of advanced technologies such as the design of the rotor blades, avionics systems, and the extensive use of composite materials.[30] The fuselage structure is modular and comprises of a aluminium-lithium alloy, designed to be both light and damage-resistant.[31] The active vibration control of structural response (ACSR) system employs vibration-canceling equipment with the intention to reduce stress on the airframe. The AW101 is rated to operate in temperatures ranging from −40 to +50 °C, and its tyres permit operating from soft or rough terrain.
The cockpit is fitted with armoured seats for the crew, and can withstand an impact velocity of over 10 m/s. Dual flight controls are provided, though the AW101 can be flown by a single person. The pilot's instrument displays include six full colour high-definition screens and an optional mission display; a digital map or forward-looking infrared (FLIR) display can also be installed.[32]
The military version of the AW101 is powered by either three Rolls-Royce/Turbomeca RTM322 turboshafts used by the UK, Japan, Denmark and Portugal; or three 1,491 kW General Electric CT7-6 turboshafts in Italy, Canada, and Japan. The Rolls-Royce RTM322 engine was specifically designed for the AW101,[33] and was later used in other helicopters such as the WAH-64 Apache.[34] Each engine is supplied by a separate 1,074 litre (276 US Gallon, 230 Imperial Gallon) self-sealing fuel tank using dual booster pumps. Optional fourth and fifth tank can be added to act as a reservoir supply, topping up the main tanks during flight, increasing range or endurance, as can airborne refuelling.[35]
The engines power an 18.59 metre diameter five-bladed main rotor. The rotor blades are constructed from carbon/glass with nomex honeycomb and rohacell foam, edged with titanium alloy. The shaping of the main rotor blades is derived from the BERP rotor blades first used on the Westland Lynx, improving aerodynamic efficiency at the blade tips and reducing the noise signature.[36] Improved BERP IV rotors have since been developed, increasing maximum takeoff weight.[29]
Computer control of the engines via the aircraft EECU's (electronic engine control unit) allows the AW101 to hover reliably in winds of over 80 km/h. Engine inlet particle separator systems provide protection when operating in sandy environments; a small apparent-secondary exhaust pipe on each engine is actually the exhaust for a rotary separator removing grit from the air intake.
The AW101's navigation system includes a GPS receiver and inertial navigation system, VHF omnidirectional radio range (VOR) instrument landing system (ILS), TACAN, and automatic direction finding. The Mk 1 and Mk 3 are equipped with a Doppler velocity system (DVS) for when the exclusive use of the conventional pitot pressure instruments might be unreliable for gauging accurate airspeed. The AW101 is equipped with helicopter management, avionics and mission systems linked by two MIL-STD-1553B multiplex and ARINC 429 databuses. A Smiths Industries OMI 20 SEP automatic flight control system provides dual redundant digital control, giving autostabilisation and four-axis autopilot operation.
Most variants of the AW101 are equipped with self-defence systems, such as chaff and flare dispensers, directed infrared countermeasures (infrared jammers), ESM (electronic support measures, in the form of RF heads), and a laser detection and warning system.[37] A chin-mounted forward looking infrared (FLIR) imaging sensor has been fitted to some variants.[38]
Two hardpoints are present on the underside of the airframe, on which the HM Mk1 model can carry four Sting Ray torpedoes or Mk 11 Mod 3 depth charges. The UK is considering equipping the Royal Navy's Merlins with the Future Anti-Surface Guided Weapon.[39] The Mk1, Mk3 and 3a variants can mount general purpose machine guns (GPMGs) in up to 5 locations in the main cabin pointing out of door and window apertures. AgustaWestland has been examining the intergration of additional ground-attack weapons, including rockets.[29]
The AW101's fuselage has a volume of 31.91 cubic metres (1,127 cu ft) and the cargo compartment is 6.5 metres (21 ft) in length, 2.3 metres (7 ft 7 in) wide and 1.91 metres (6 ft 3 in) high. The military version of the AW101 can accommodate up to 24 seated or 45 standing combat troops and their equipment. Alternative loads include a medical team and 16 stretchers, and cargo pallets.[40]
The cabin floor and rear ramp are fitted with flush tie-down points, a semi-automatic cargo release unit (SACRU). The ramp, 1.91 by 2.3 metres (6 ft 3 in × 7 ft 7 in), can take a 3,050-kilogram (6,700 lb) load, allowing it to carry vehicles such as Land Rovers.[41] A cargo hook under the fuselage can carry external loads of 5,440 kilograms (12,000 lb) via the use of a SACRU.[42] A rescue hoist and a hover trim controller are fitted at the cargo door.
The RN's final order was for 44 ASW machines, originally designated Merlin HAS.1 but soon changed to Merlin HM1. The first fully operational Merlin was delivered on 17 May 1997, entering service on 2 June 2000. All aircraft were delivered by the end of 2002, and are operated by four Fleet Air Arm squadrons, all based at RNAS Culdrose in Cornwall: 814 NAS, 820 NAS, 824 NAS and 829 NAS. 700 NAS was the Merlin Operational Evaluation Unit from 2000 to 2008.
In March 2004, RN Merlins were grounded following an incident at RNAS Culdrose when the tail rotor failed on one of them. Investigations revealed that this was due to tail rotor hub manufacturing defects.[43] Flights resumed the following year.
The Merlin HM1 has been cleared to operate from the Royal Navy's aircraft carriers, amphibious assault ships, Type 23 frigates and a number of RFA vessels including the Fort Victoria class. It is to equip the Type 45 destroyers. A Capability Sustainment Programme is currently in place to upgrade 30 aircraft to the Merlin HM2 standard. This will include a new mission system and digital cockpit. It had been planned to include the remaining 8 airframes but this has now been dropped for financial reasons while alternative roles were sought for these aircraft.[44]
The UK had long considered the Merlin as a replacement for the Sea King ASaC7 in the airborne early warning (AEW) role.[45] On 15 December 2009, the UK announced plans to move RAF Merlin HC3s and HC3As to the Commando Helicopter Force. The Merlins would replace 'junglie' Sea King HC4 helicopters.[46] The Sea King is also to be replaced in the SAR role, resulting in its retirement by 2016. Then the Navy will operate the Lynx Wildcat and Merlin, the RAF operating Puma and Chinook, and Army operating Lynx Wildcat and Apache.[46]
The Lynx helicopter has been seen as a useful complement to the newer Merlins. However in 1995 it was decided to phase out Lynx for an all-Merlin fleet in maritime use.[47] It is intended that 846 NAS reforms with ex-RAF Merlin HC3s in 2015. They would be followed by 845 NAS operating the fully navalised Merlin HC4 in 2017.[48]
Royal Navy Merlins have seen action in the Caribbean, on counter-narcotics and hurricane support duties. They have also been active in Iraq, providing support to British and coalition troops on the ground, as well as maritime security duties in the North Persian Gulf.
RAF ordered 22 transport helicopters designated Merlin HC3, the first of which entered service with No. 28 Squadron RAF, based at RAF Benson, in January 2001. The type is equipped with extended-range fuel tanks and is capable of air-to-air refueling; however, due to the lack of a suitable UK tanker aircraft, this capability has not been cleared for use. It also differs from the Royal Navy version by having double-wheel main landing gear, whereas the RN version only has a single wheel on each of the main gears.
Depth maintenance of Merlin HC3 is carried out at the Merlin Depth Maintenance Facility at RNAS Culdrose.[49] The first operational deployment was to the Balkans in early 2003. They were deployed to southern Iraq as part of Operation Telic until July 2009 when British Forces withdrew from Iraq.
To alleviate a shortfall in operational helicopters and to allow Merlins to be deployed in Afghanistan, the British Ministry of Defence acquired six DMRH AW101s from Denmark in 2007, which were assigned to the RAF with the designation Merlin HC3A.[50] As part of the deal, the Ministry of Defence ordered six new-build replacements for the Royal Danish Air Force. In December 2007, a second Merlin squadron, No. 78 Squadron was formed at Benson.[51] Five Merlin Mk3s are operating in Afghanistan in 2010; their initial deployment was criticised as they allegedly lack Kevlar armour,[52] the aircraft are now fully fitted with ballistic protection armour supplied by Permali Gloucester Limited.[53]
In 1997, the Italian government ordered 20 EH101 helicopters with four options for the Italian Navy. These EH101s included 10 anti-surface and anti-submarine (ASW) versions, 4 early-warning (AEW) versions, 4 utility versions, and 4 Amphibious Support Helicopter (ASH) versions.[54]
The first Italian Navy production helicopter (MM81480) was first flown on 4 October 1999 and was officially presented to the press on 6 December 1999 at the Agusta factory. Deliveries started in 2001 and were completed by 2006. Italian EH101s operate from a variety of ships, including aircraft carriers and amphibious assault ships. The 9th ASW helicopter was delivered on August 2009.
The AW101 was also chosen for CSAR program; the Aeronautica Militare (Air Force) has a requirement for up to 12 AW101s to replace HH-3F helicopters with delivery from 2014.[55]
The Italian navy deployed three AW101s to Afghanistan in 2010, flying them in transport and utility roles.[56]
In 2001, the Royal Danish Air Force announced the purchase of eight EH101s for SAR duties and six tactical troop transports.[57] The last of the 14 EH101s was delivered 1 March 2007 and the first SAR EH101s became operational in late April 2007. The Danish Mk 512s have a MTOW of 15,600 kg.
In 2007, the British Ministry of Defence acquired the six troop transport AW101s from Denmark to alleviate a shortfall in British operational helicopters. In exchange, the British government ordered six new-build helicopters from AgustaWestland as replacements for the Royal Danish Air Force.
On 28 January 2008, one Danish AW101 broke the drive shaft from one engine to the gear box and made an emergency landing at Billund Airport. Following this incident the Danish fleet was grounded as a safety precaution. The incident provoked national debate about the future of the EH101 in Danish service and whether it made sense to acquire different helicopters, since the EH101 had very low availability of roughly 30% due to mechanical issues. AgustaWestland in turn blamed the Danes for ordering spare parts very late and not keeping enough staff to properly service the helicopters.[58] In April 2008, RDAF reported considerable improvements in operational availability of over 50%, citing improved service from AW (speedy delivery of spare parts) and increased proficiency of ground crews as responsible. Number 6 replacement for the helicopters taken over by British RAF was delivered January 20th 2010.
The Portuguese Air Force has operated Merlins since 24 February 2005 to conduct transport, search and rescue, and maritime surveillance missions. The 12 aircraft began to gradually replace the Aérospatiale Puma that previously conducted these missions. The aircraft were purchased at a cost of €446.[59]
The main role of the Portuguese AW101 is search and rescue in Portugal's maritime zone. AW101s are on constant alert at three bases: Montijo (near Lisbon), Lajes Field, Azores and Porto Santo Island.
The Japan Maritime Self-Defense Force ordered 14 aircraft in 2003 to use in both the airborne mine countermeasures (AMCM) and transport roles.[60] The AW101 was modified by Kawasaki Heavy Industries, and the Japan Defense Agency designated the model MCH-101. Characteristics of this model were automated folding of the rotor and tail, and an active anti-vibration system.[61]
AgustaWestland, Kawasaki and Marubeni entered a general agreement in 2002. Kawasaki began assembly of the CH-101 and the MCH-101 in 2003. The MEXT uses the CH-101 on its Antarctic transportation missions. Kawasaki began licensed production of the Rolls-Royce/Turbomeca RTM322 turboshaft engines in 2005.[62] The first MCH-101 was delivered to the Self-Defense Force on March 3, 2006.[60][61]
The MCH-101 and CH-101 will replace the MH-53E (S-80-M-1) for AMCM, and the Sikorsky S-61 in a support role for Japanese Antarctic observation missions.[63] AgustaWestland received an order for 14 MCH-101 and CH-101, and another 12 aircraft will be assembled by Kawasaki in Japan.[64] Under agreement between Marubeni and AgustaWestland, a spare parts depot was established in Japan to provide support for its MCH-101 and CH-101 fleet.[65]
There has been a considerable demand for the AW101; which has kept a continuous queue of customers for over five years.[66]
Norway has expressed an interest in the AW101 as a candidate for the Norwegian All Weather Search and Rescue Helicopter (NAWSARH) programme, that is planned to replace the Westland Sea King Mk.43B of the Royal Norwegian Air Force in 2015.[67] The other candidates for the NAWSARH contract of 10-12 helicopters are Bell Boeing V-22 Osprey, Eurocopter EC225, NHIndustries NH-90 and Sikorsky S-92.[68] Iceland also cooperates with Norway in this programme and is interested in 3-4 helicopters to replace its fleet of Super Puma helicopters.[69]
South Korea has recognised the need to modernise their airborne mine countermeasures (AMCM) maritime helicopter fleet, and the AW101 is one of the helicopters being studied for the role.[70]
In November 2007, Algeria signed a contract for six AW101 helicopters.[71] This is one of several deals that may potentially follow according to the MOD.[72]
AgustaWestland has developed a luxury variant of the AW101, the AW101 VVIP (Very Very Important Person, i.e. a head of state), targeted at business and VIP customers.[73] As of April 2009, 15% of all AW101s sold have been for VIP purposes.[29]
The United States Marine Corps began acquiring the AW101 as the intended replacement of its fleet of Marine One helicopters, used by the President and other key political figures, under the VXX program; designated VH-71, this aircraft was heavily customised with specialised equipment and defensive systems.[74] However, on 6 April 2009, the VH-71 was abruptly terminated when funding was withdrawn.[75] AgustaWestland teamed up with Boeing in 2010 to enter the AW101 in the restarted VXX.[76]
Other customers have emerged for the VIP variant; a Saudi Arabian order was placed in 2009.[29] In April 2009, India ordered 12 AW101 to serve as executive transport helicopters for the Indian President and Prime Minister.[77][78] The AW101 was selected after competing against the Sikorsky S-92 in field trials in 2008. One particular requirement was that the helicopter have a high tail boom, to allow most ground vehicles to come close to the helicopter's rear exit, for reduced threat exposure.[79]
Data from Jane's All The World's Aircraft 2003–2004[95]
General characteristics
Performance
Armament
Avionics
|
|
|