The Agusta-Westland EH101 & NH Industries NH90

v2.0.1 / 01 jan 03 / greg goebel / public domain

* As aerospace development programs have become more complicated and expensive over the last decades, countries have increasing pooled their resources to share program costs. Helicopters have been part of this trend, resulting in international programs to develop the Agusta-Westland "EH101" and the NH Industries "NH90". These are state of the art rotorcraft, intended for transport, maritime warfare, and search and rescue roles.

This document provides a short overview of the EH101 and NH90.



* In the late 1970s, confronted with hundreds of Soviet attack submarines that threatened the sea lanes connecting Europe to America in time of war, the British Royal Navy (RN) and the Marina Militaire Italiane (MMI / Italian Navy) formulated a requirement for an advanced antisubmarine warfare (ASW) helicopter, to replace the Sikorsky-Agusta-Westland Sea King then in service for this role.

Westland of Britain's initial studies for a "Sea King Replacement (SKR)" were given the designation "WG.34". Basic requirements were for a helicopter that was more compact than the Sea King, but had a greater lift capability, and of course general improvements in operational performance and maintainability.

Discussions between Westland and Agusta of Italy on the SKR quickly resulted in the formation in June 1980 of a joint company named "European Helicopter (EH) Industries", with its headquarters in London, to develop the new helicopter, which was designated "EH101". Work was apportioned between the two parent companies to give them roughly equal shares without duplication.

As design studies progressed, it was decided that transport versions should be developed as well. Ultimately, a number of different EH101 variants were proposed:

A full-scale mockup of the EH101 was displayed at the Paris Air Show in 1985. A single ground test airframe called the "Iron Bird" and a total of nine flying preproduction prototypes ("PP"s) were built:

Initial production orders for the EH101 took place in 1991, with civil certification for the UK, Italy, and US following in 1994.

* The EH101 emerged as an attractive, sleek helicopter of generally conventional configuration, with a main rotor and a tail rotor. It features a five-blade main rotor with paddles on the end of the blades, a four-blade tail rotor, and retractable undercarriage. It is powered by three turboshaft engines, with the engine type depending on the variant. The rotors are made of composite materials, while the fuselage is made of honeycomb lithium-aluminum alloy, with composite paneling. The tail boom folds forward, except in variants with a rear loading ramp.

The EH101 has an emergency floatation system using helium-inflated polyethylene-kevlar floats, as well as anti-icing features such as sideways-facing turbine inlets, provided because icing was a severe problem with the Sea King. The EH101 has a single-point pressure refueling system that allows the aircraft to be "topped off" in a few minutes.

* Development of the EH101 was protracted, for a number of reasons:

In July 2000, EH Industries was replaced by a full merger of Agusta and Westland, known simply as "Agusta-Westland", and the EH101 is now properly referred to as the "Agusta-Westland EH101".



* The two British EH101 variants are the Royal Navy's "Merlin HM.1" ASW helicopter and the Royal Air Force's (RAF) "Merlin HC.3" combat transport. Both are powered by three Rolls-Royce Turbomeca RTM322-01/8 or RTM332-02/8 turboshaft engines with 1,575 shaft kilowatts (2,100 shaft horsepower) for takeoff.

The Merlin HM.1 is an impressive aircraft, but its development has not been smooth. The procurement plan ran well over budget and was more than five years behind schedule. However, aircrews were enthusiastic when they received the new helicopter, praising it as "simple to handle, extremely capable, and agile."

They were very impressed with its avionics and particularly its autopilot system. The Merlin's "Joint Tactical Information Display System (JTIDS)" data link capability is a particular plus, allowing operators to access "floods of data", and the helicopter is highly maintainable.

   _____________________   _________________   ___________________
   spec                    metric              english
   _____________________   _________________   ___________________

   fuselage length         19.5 meters         64 feet
   length (with rotor)     22.8 meters         74 feet 9 inches
   height (with rotor)     6.65 meters         21 feet 10 inches
   main rotor diameter     18.6 meters         61 feet

   empty weight:           10,500 kilograms    23,150 pounds
   maximum speed:          309 KPH             192 MPH / 167 KT
   cruise speed:           278 KPH             173 MPH / 150 KT
   service ceiling:        4,575 meters        15,000 feet
   _____________________   _________________   ___________________

The Merlin HM.1 carries a pilot, copilot-observer, and two electronics systems operators. The helicopter's electronics suite, integrated by Lockheed Martin UK, provides formidable combat capabilities. The suite includes an active Thomson Marconi dipping sonar that is so powerful that two HM.1s can effectively monitor the entire English channel for submarine activity. The HM.1 also carries a suite of various types of sonobuoys, packed in two rotary stores stations in the rear of the cabin.

The Merlin carries a Blue Kestrel 5000 radar on the underside of the fuselage that provides 360-degree coverage and guidance capability for antiship missiles. An Orange Reaper (Racal Kestrel) electronic support measures (ESM) system uses six antennas to detect, locate, and identify about 2,000 different types of emitters.

Sensor data is processed, fused, and displayed by the Common Control Unit processor, which interfaces to the pilot, co-pilot, and to electronic systems operators in the cabin. The data is displayed overlaid on digital maps of the seabed. The HM.1 carries a set of radios fitted for encrypted communications. The only armament qualified so far for the Merlin HM.1 is the Marconi Stingray torpedo, with the helicopter carrying up to four, but EH101 mockups were displayed with Exocet antiship missiles and it is very likely that other weapons, such as the Sea Skua antiship missile, will be qualified as well.

The Royal Navy has 44 Merlin HM.1s on order. The type is to be operated off Type 23 Duke-class frigates, Invincible-class carriers, and other RN combat vessels. The first production aircraft flew on 6 December 1995, and the first fitted with operational avionics flew on 14 January 1997.

A flight trials unit was formed as Number 700M Squadron on 1 December 1998. Number 824 Naval Air Squadron was formed for training in June 2000. The first frontline Merlin squadron, Number 814, was commissioned in late 2001, to be followed by Number 820 and Number 829 Squadron.

* The RAF Merlin HC.3 can accommodate 30 troops, sixteen stretchers, or other loads of similar size. The first HC.3 flew on 24 December 1998. Initial operating capability was achieved in the summer of 2000, with the type going into service with RAF Number 28 and Number 72 Squadrons.

The RAF's Merlin HC.3 transport is less sophisticated than the HM.1, and has not suffered as much from development problems. The HC.3 differs from the HM.1 in having a rear-fuselage loading ramp, and of course does not have the complicated ASW avionics fit of the HM.1.

However, the HC.3 is well-fitted for combat operations, with kit suggesting that it will be used for combat search and rescue (CSAR) or special operations missions. The HC.3 has a comprehensive electronics countermeasures (ECM) suite, the cockpit is designed to be compatible with night-vision goggles, and a forward-looking infrared (FLIR) imager can be fitted in the nose. A mid-air refueling probe can be installed as well, and there are pintles for mounting machine guns.

The British government is also considering a possible requirement for a Support Amphibious Battlefield Rotorcraft, which may lead to more EH101 orders from the UK.



* The three MMI variants of the EH101 are powered by three General Electric (GE) T700-GE-T6A engines with 1,530 shaft kilowatts (2,040 shaft horsepower) for takeoff. Italy has ordered sixteen EH101s, with the first flying on 6 December 1999, and final delivery scheduled for 2004.

The three variants include:

Agusta-Westland believes that Italy may order more EH101s, as the original requirement was for 36 aircraft.

* The Canadians were the next major buyer of the EH101, in the form of the "AW520 Cormorant" search and rescue (SAR) variant. The original Canadian request, issued in 1993, was for 43 aircraft, including the CH-148 Petrel ASW variant and CH-149 Chimo SAR variant, but this was cancelled when the Canadian Liberal Party came to power in 1993. However, the need for SAR helicopters for North Atlantic rescue operations remained outstanding, and 15 Cormorants were ordered in 1998 for the SAR role.

The Cormorant is based on the civil version of the EH101 as a cost-saving measure, and has a rear loading ramp and a rescue winch. The first Cormorant took to the air on 31 May 2000 at the Agusta plant in Italy, and was flown across the Atlantic in early 2001 for service with the 442 Transport & Rescue Squadron at Comox in British Columbia. Five of the Cormorants will be sent there in total, initially for operational training, while the other ten will be split up between 413 Squadron at Greenwood, Nova Scotia, and 103 Squadron at Gander, Newfoundland.

The Canadians are also considering replacement of their shipborne Sea King helicopters, with a potential order for 30 new aircraft, essentially another pass at the same requirement that the CH-148 Petrel had been supposed to fill a decade earlier.



* Civilian models of the EH101 are powered by GE CT7-6 engines with 1,440 shaft kilowatts (1,920 shaft horsepower) for takeoff. There have been no sales of the Heliliner, which like the Merlin HC.3 can accommodate 30 passengers, but a single Series 510 was sold to the Tokyo Metropolitan Police Agency, with service entry in March 1999.

By mid-2000, Agusta-Westland had orders and commitments for close to 100 helicopters. Sales then went slow, compounded by a global economic slowdown that began at the end of 2000, but picked up with a number of new orders:



* The NH90 began life in the early 1980s as a European multinational development program for a new multi-purpose transport and naval helicopter, intended to replace the Bell UH-1 Huey, Aerospatiale Puma, Westland Lynx, and Sikorsky Sea King. The program was formally initiated in August 1992, with the participation of France, Germany, Italy, and the Netherlands.

The NH Industries consortium is headquartered in Aix-en-Provence in France, with the work done by Agusta-Westland, Eurocopter France, Eurocopter Germany, and Fokker Aviation in the Netherlands. The first three manufacturers have a little over a 30% share each, while Fokker's share is about 5%. Norway became a "risk-sharing partner" of Eurocopter France in 1994. Portugal joined the group in June 2001, and has a 1.5% workshare.

The NH90 is of conventional appearance, with a main / tail rotor configuration and tricycle retractable landing gear. The default powerplants are two Rolls-Royce / Turbomeca RTM 322-01/9 turboshafts with a maximum rating of 1,575 shaft kilowatts (2,100 shaft horsepower) each, although the Italians have specified General Electric T700-T6E turboshafts with 1,530 shaft kilowatts (2,040 shaft horsepower) each, and other users may specify this fit as well.

Both types of engines have full authority digital engine control (FADEC). The power transmission system has a maximum rating of 2,560 kilowatts (3,413 horsepower), so the engines will not be run at maximum power unless one fails. The NH90 is also fitted with an auxiliary power unit (APU) for self-starting and ground operation.

The main rotor system uses four composite blades with flared tips and a titanium hub. The tail rotor is of similar configuration. The machine's crashworthy airframe is built mostly of composite materials. There is a large sliding door on both sides of the machine, and crew exit doors on both sides of the cockpit.

The NH90 is designed for survivability, reliability, and ease of maintenance. It has an automatic fire detection and extinguisher system; crash resistant, self-sealing fuel tanks; a dual redundant hydraulic system; and dual redundant MILSTD 1553B data buses. It has built in monitoring and diagnostic systems.

The machine's glass cockpit has five 20 by 20 centimeter (8 by 8 inch) color flat panel displays. The NH90 can be optionally fitted with a FLIR turret in the nose, as well as defensive countermeasures aids.

* The NH90 is being offered in two different forms, the "NATO Frigate Helicopter (NFH)" and the "Tactical Transport Helicopter (TTH)".

The NFH is intended for ASW and maritime surface warfare, though it can be used for SAR and transport roles in a pinch. It has an automatic rotor and tail folding system, plus a combat avionics suite, including a 360 degree search radar in a drum under the fuselage, magnetic anomaly detector, dipping sonar or sonobuoys, emitter location system, and a "Link 11" datalink system.

The NFH can carry up to 700 kilograms (1,545 pounds) of stores, including antiship missiles, homing torpedoes, and air to air missiles. Standard crew is pilot, copilot, and one or two systems operators. The pilot wears a Thales helmet-mounted sight system.

The TTH lacks the offensive avionics systems of the NFH, though it is fitted with weather radar. It has infrared exhaust suppressors; armored crew seats; a cable cutter; a night vision goggle compatible cockpit; and an optional rear loading ramp. Standard crew is pilot and copilot, with a payload capacity of 20 troops, 12 stretchers, a light tactical vehicle, or 2,500 kilograms (5,500 pounds) of cargo. The TTH can be fitted with defensive armament.

   _____________________   _________________   _______________________
   spec                    metric              english
   _____________________   _________________   _______________________

   main rotor diameter     16.3 meters         53 feet 6 inches
   tail rotor diameter     3.2 meters          10 feet 6 inches
   fuselage length         15.88 meters        52 feet 1 inch
   footprint length        19.56 meters        64 feet 2 inches
   height (tail rotor)     5.44 meters         17 feet 10 inches

   empty weight            6,800 kilograms     14,995 pounds
   max loaded weight       10,000 kilograms    22,000 pounds

   max cruise speed        260 KPH             160 MPH / 140 KT
   service ceiling         6,000 meters        19,700 feet
   range                   880 kilometers      550 MI / 475 NMI
   _____________________   _________________   _______________________

   The TTH has a smaller empty weight of 5,400 kilograms (11,900 pounds)
   and a higher cruise speed of 290 KPH (180 MPH).

Five NH90 prototypes were built:

Initial production delivery, of a TTH machine to Germany, is expected in the spring of 2004.



* A total of 253 NH90s are to be built for the four original partner organizations, including 160 TTHs and 93 NFHs. Italy has ordered 116, Germany 80, France 27, the Netherlands 20, and Portugal 10. The partners also have 55 options, and are planning further buys for a total of 297 machines.

The NH-90 won its first substantial foreign order in 2000. Sweden, Finland, Norway, and Denmark issued a joint request for a new "Nordic Standard Helicopter" and evaluated machines from most of the major helicopter manufacturers. The Danes dropped of the group and, as mentioned above, selected the EH101 as they felt they needed a larger machine for the SAR role, but the other three nations chose the NH-90:

In late 2002, the Greek Army ordered 42 NH-90s, towards a possible total of 60. This award makes Greece the ninth country to buy the NH-90. The machines will presumably be TTHs, but details and schedules have not yet been announced as contract work is still underway.

Agusta-Westland's participation in the NH90 program means the company is competing with itself to a degree with the EH101, but the EH101 is a larger machine and fits into a somewhat different niche.



* Sources include:

The EH101 and NH90 files in the FLUG-REVUE database was used as well.

* Revision history:

   v1.0   / 01 nov 00 / gvg
   v1.0.1 / 01 nov 01 / gvg / Minor cosmetic update.
   v2.0.0 / 01 jun 02 / gvg / Added NH90 materials.
   v2.0.1 / 01 jan 03 / gvg / Portugal EH101 order, Greek NH-90 order.