Introduction
The Aérospatiale Gazelle is a five-seat helicopter, commonly used for light transport, scouting and light attack duties. It is powered by a single turbine engine and was the first helicopter to feature a fenestron tail instead of a conventional tail rotor. It was designed by Sud Aviation, later Aérospatiale, and manufactured in France and the United Kingdom through a joint production agreement with Westland Aircraft. Further manufacturing under license was performed by SOKO in Yugoslavia and the Arab British Helicopter Company (ABHCO) in Egypt.
Since being introduced to service in 1973, the Gazelle has been procured and operated by a number of export customers. It has also participated in numerous conflicts around the world, including by Syria during the 1982 Lebanon War, by Rwanda during the Rwandan Civil War in the 1990s, and by numerous participants on both sides of the 1991 Gulf War. In French service, the Gazelle has been supplemented as an attack helicopter by the larger Eurocopter Tiger, but remains in use primarily as a scout helicopter.
Development
The Gazelle originated in a French Army requirement for a lightweight observation helicopter intended to replace the Aérospatiale Alouette III; early on in the aircraft's development, the decision was taken to enlarge the helicopter to enable greater versatility and make it more attractive for the export market. In 1966, Sud Aviation began working on a light observation helicopter to replace its Alouette II with seating for five people. The first prototype SA 340 flew for the first time on 7 April 1967, it initially flew with a conventional tail rotor taken from the Alouette II. The tail was replaced in early 1968 with the distinctive fenestron tail on the second prototype. Four SA 341 prototypes were flown, including one for British firm Westland Helicopters. On 6 August 1971, the first production Gazelle conducted its first flight. On 13 May 1967, a Gazelle demonstrated its speed capabilities when two separate world speed records were broken on a closed course, achieving speeds of 307 km/h over 3 kilometres and 292 km/h over 100 kilometres.
Early on, the Gazelle had attracted British interest, which would culminate in the issuing of a major joint development and production work share agreement between Aerospatiale and Westland. The deal, signed in February 1967, allowed the production in Britain of 292 Gazelles and 48 Aérospatiale Pumas ordered by the British armed forces; in return Aérospatiale was given a work share in the manufacturing programme for the 40 Westland Lynx naval helicopters for the French Navy. Additionally, Westland would have a 65% work share in the manufacturing, and be a joint partner to Aérospatiale on further refinements and upgrades to the Gazelle. Westland would produce a total of 262 Gazelles of various models, mainly for various branches of the British armed forces, Gazelles for the civil market were also produced.
It also served with all branches of the British armed forces—the Royal Air Force, Royal Navy (including in support of the Royal Marines) and the British Army in a variety of roles. Four versions of the Gazelle were used by the British forces. The SA 341D was designated Gazelle HT.3 in RAF service, equipped as a helicopter pilot trainer (hence HT). The SA 341E was used by the RAF for communications duties and VIP transport as the Gazelle HCC.4. The SA 341C was purchased as the Gazelle HT.2 pilot trainer for the Royal Navy; training variants have been replaced by the Squirrel HT1. The SA 341B was equipped to a specification for the Army Air Corps as the Gazelle AH.1 (from Army Helicopter Mark 1).
The Gazelle proved to be a commercial success, which led Aerospatiale to quickly develop and introduce the SA 341 Gazelle series, which was equipped with considerably more powerful engines. Licensed production of the type did not just take place in the UK, domestic manufacturing was also conducted by Egyptian firm ABHCO. Yugoslavian production by SOKO reportedly produced a total of 132 Gazelles. As the Gazelle became progressively older, newer combat helicopters were brought into service in the anti-tank role; thus those aircraft previously configured as attack helicopters were often re-purposed for other, secondary support duties, such as an Air Observation Post (AOP) for directing artillery fire, airborne forward air controller (ABFAC) to direct ground-attack aircraft, casualty evacuation, liaison, and communications relay missions.
Design
The Aérospatiale Gazelle is an agile, fast-moving helicopter, originally developed as a replacement to Aérospatiale's Alouette helicopter family. While some aspects of the Gazelle, such as its purpose and layout resembles the preceding Alouette, the Gazelle featured several important innovations. It was the first helicopter to carry a fenestron or fantail; this is a shrowded multi-blade anti-torque device housed internally upon the vertical surface of the Gazelle's tail, which replaces a conventional tail rotor entirely. The fenestron, while requiring a small increase in power at slow speeds, has advantages such as being considerably less vulnerable and low power requirements during cruise speeds, and has been described as "far more suitable for high-speed flight". The fenestron is likely to have been one of the key advances that allowed the Gazelle to become the world's fastest helicopter in its class.
The main rotor system had originally based upon the rigid rotor technology developed by Messerschmitt-Bölkow-Blohm for the MBB Bo 105; however, due to control problems experienced while at high speeds upon prototype aircraft, the rigid rotor was replaced with a semi-articulated one on production aircraft. The difficulties experienced with the early design of the main rotor was one of the factors contributing to the lengthy development time of the Gazelle. The individual rotor blades were crafted out of composite materials, primarily composed of fibreglass, and had been designed for an extremely long operational lifespan; composite rotor blades would become a common feature of later helicopters. The main rotor maintains a constant speed in normal flight, and is described as having a "wide range of tolerance" for auto-rotation.
The Gazelle is capable of transporting up to five passengers and up to 1,320 pounds of cargo on the underside cargo hook, or alternatively up to 1,100 pounds of freight in 80 cubic feet of internal space in the rear of the cabin. Armed variants would carry a 20mm nose-mounted cannon and up to four HOT (Haut subsonique Optiquement Téléguidé Tiré d'un Tube) wire-guided anti-tank missiles. Various optional equipment can be installed upon the Gazelle, such as fittings for engine noise suppression, 53 gallon ferry tanks, a rescue winch capable of lifting up to 390 pounds, emergency flotation gear, particle filter, high landing skids, cabin heater, adjustable landing lights, and engine anti-icing systems. While the Gazelle had been developed under a military-orientated design programme, following the type's entry to service increasing attention to the commercial market was paid as well. The type was marketed to civil customers; notably, civilian operator Vought Helicopters at one point had a fleet of at least 70 Gazelles. Civil-orientated Gazelles often included an external baggage access door mounted beneath the main cabin.
The Gazelle was the first helicopter to be adapted for single-pilot operations under instrument flight rules. An advanced duplex autopilot system was developed by Honeywell in order to allow the pilot to not be overworked during solo flights; the Gazelle was chosen as the platform to develop this capability as it was one of the faster and more stable helicopters in service at that point and had a reputation for being easy to fly. The docile flying abilities of the Gazelle are such that it has been reported as being capable of comfortably flying without its main hydraulic system operation at speeds of up to 100 knots. The flight controls are highly responsive; unusually, the Gazelle lacks a throttle or a trimming system. Hydraulic servo boosters are present on all flight control circuits to mitigate control difficulties in the event of equipment failure.
The Gazelle was designed to be easy to maintain, all bearings were life-rated without need for continuous application of lubrication and most fluid reservoirs to be rapidly inspected. The emphasis in the design stage of achieving minimal maintenance requirements contributed towards the helicopter's low running costs; many of the components were designed to have a service life in excess of 700 flying hours, and in some cases 1,200 flight hours, before requiring replacement. Due to the performance of many of the Gazelle's subsystems, features pioneered upon the Gazelle such as the fenestron would appear upon later Aerospatiale designs.
As the Gazelle continued to serve into the 21st century, several major modernization and upgrade programs were undertaken, commonly adding new avionics to increase the aircraft's capabilities. Aerotec group offered an overhaul package to existing operators, which comprised upgraded ballistic protection, night vision goggles, new munitions including rockets and machine guns, and 3D navigational displays; as of 2013, Egypt is said to be interested in upgrading their domestically-built Gazelles. QinetiQ developed a Direct Voice Input (DVI) system for the Gazelle, it has been installed and is operating on those aircraft used by the British Army Air Corps; the DVI system enables voice control over many aspects of the aircraft, lowering the demands placed upon the crew. In September 2011, QinetiQ and Northrop Grumman proposed outfitting former British Gazelles with autonomous flight management systems derived from the Northrop Grumman MQ-8 Fire Scout, converting them into unmanned aerial vehicles (UAV)s to meet a Royal Navy requirement for an unmanned maritime aerial platform.
United Kingdom
In 1973, 142 aircraft were on order by the UK, out of a then-intended fleet of 250. No. 660 Squadron AAC, based in Salamanca Barracks, Germany, was the first British Army unit to be equipped with Gazelles, entering operational service on 6 July 1974. The Gazelles, replacements for the Sioux, were assigned the roles of reconnaissance, troop deployment, direction of artillery fire, casualty evacuation and anti-tank operations. In August 1974, 30 were based at CFS Tern Hill for RAF helicopter training.
The Royal Navy's Gazelles entered service in December 1974 with 705 Naval Air Squadron, Culdrose, to provide all-through flying training in preparation for the Lynx's service entry. A total of 23 Gazelles were ordered for Culdrose. Army-owned AH.1s also entered service with the Commando Helicopter Force (CHF) of the Fleet Air Arm, where they operated as utility and reconnaissance helicopters in support of the Royal Marines. The 12 Gazelles for 3 Commando Brigade Air Squadron had entered service in 1975, by which time, there were 310 Gazelles on order for the British military.
Gazelles that had replaced the Siouxs in RAF Sek Kong towards the end of 1974 had been found unsuitable for Hong Kong and, by the end of 1975, had been returned to the UK. During its Cold War service period, the Army Gazelles flew over 660,000 hours and had over 1,000 modifications made to the aircraft. From the early 1980s, Army-operated Gazelles were fitted with the Gazelle Obvervation Aid, a gyro-stabilised sight to match their target finding capability with that of the Lynx.
The type was also frequently used to perform airborne patrols in Northern Ireland. On 17 February 1978, a British Army Gazelle crashed near Jonesborough, County Armagh, after coming under fire from the Provisional IRA during a ground skirmish.
During the Falklands War, the Gazelle played a valuable role operating from the flight decks of Royal Navy ships. Under a rapidly-performed crash programme specifically for the Falklands operation, Gazelles were fitted with 68mm SNEB rocket pods and various other optional equipment such as armour plating, flotation gear and folding blade mechanisms. Two Royal Marine Gazelles were shot down on the first day of the landings at San Carlos Water. In a high-profile incident of friendly fire on 6 June 1982, an Army Air Corps Gazelle was mistaken for a low-flying Argentine C-130 Hercules and was shot down by HMS Cardiff, a British Type 42 Destroyer.
The Gazelle also operated in a reconnaissance and liaison roles during the War in Afghanistan. In 2007, it was reported that, while many British helicopters had struggled with the conditions of the Afghan and Iraqi theatres, the Gazelle was the "best performing model" with roughly 80% being available for planned operations.
Various branches of the British military have operated Gazelles in other theatres, such as during the 1991 Gulf War against Iraq and in the 1999 intervention in Kosovo. While the type was originally intended to be retired in 2012, the Gazelle will continue to be operated in a policing capacity in Northern Ireland until 2018, at which point the Police Service of Northern Ireland is to have the assets to fill this role itself.
British Variants
SA 341B (Westland Gazelle AH.1)
Version built for the British Army; Featured the Astazou IIIN2 engine, capable of operating a nightsun searchlight, later fitted with radio location via ARC 340 radio and modified to fire 68mm SNEB rockets. First Westland-assembled version flown on 31 January 1972, this variant entered service on 6 July 1974. A total of 158 were produced. A small number were also operated by the Fleet Air Arm in support of the Royal Marines.
SA 341C (Westland Gazelle HT.2)
Training helicopter version built for British Fleet Air Arm; Features included the Astazou IIIN2 engine, a stability augmentation system and a hoist. First flown on 6 July 1972, this variant entered operational service on 10 December 1974. A total of 30 were produced.
SA 341D (Westland Gazelle HT.3)
Training helicopter version built for British Royal Air Force; Featuring the same engine and stability system as the 341C, this version was first delivered on 16 July 1973. A total of 14 were produced.
SA 341E (Westland Gazelle HCC.4)
Communications helicopter version built for British Royal Air Force; Only one example of this variant was produced.
Specifications (SA 341)
Crew: 2
Capacity: 3 Passengers
Length: 11.97 m (39 ft 0 in)
Main rotor diameter: 10.5 m (34 ft 6 in)
Height: 3.15 m (10 ft 3 in)
Main rotor area: 86.5 m2 (931 ft2)
Empty weight: 908 kg (2,002 lb)
Gross weight: 1,800 kg (3,970 lb)
Powerplant: 1 × Turbomeca Astazou IIIA turboshaft, 440 kW (590 hp)
Maximum speed: 310 km/h (193 mph)
Cruising speed: 264 km/h (164 mph)
Range: 670 km (416 miles)
Service ceiling: 5,000 m (16,405 ft)
Rate of climb: 9 m/s (1,770 ft/min)
