RAN Helicopters

RAN Helicopters

by Anthony Haigh
This essay was a distinguished entry in the 2002 Naval Officers Club Literary Prize competition.
 
Considering the relatively short time it has been around, the development of the Australian naval helicopter as a maritime weapons system has been impressive. Over a fifty-year period, and through nine different types, it has developed from a simple utility platform to a sophisticated strike aircraft.

sycamore
Where it all began, the 1953 Bristol Sycamore HR Mk 50.

 That development obviously owes much to the technological advances that have been made since 1953 when the RAN’s first helicopters were delivered: piston engines have given way to jets; rotor blades are now made from light but strong composite materials, as opposed to metal; navigation is managed by computers, that take their information from satellites, inertial units and radar; and the computer itself represents a huge advance. But the development is also testament to Australia’s willingness to respond to the changing face of maritime warfare. From the ‘flat-top’ aircraft carrier traditionally associated with naval aviation to the modem frigate operating one or two helicopters, the Australian Fleet Air Arm has moved with the times.

A short history

Australian naval aviation had been in existence for some time, in various forms, before the introduction of helicopters. Australians flew in World War I with the Royal Navy Air Service, and in the early 1920s the RAN built its first ‘aircraft carrier’: HMAS Albatross, a seaplane carrier. However, the successes enjoyed by Royal Navy and United States Navy aircraft carriers during World War II convinced Australia to form its own Fleet Air Arm, based around two aircraft carriers.

The carriers were British Majestic Class light fleet carriers: HMA Ships Sydney and Melbourne (laid down as HM Ships Terrible and Majestic respectively). Sydney was acquired in December 1948 but at this time several advances were being made in the field of carrier design: notably, the angled flight deck and the mirror landing system.

It was decided to incorporate these features into Melbourne, making her the first operational carrier in the world to embody them. However, the modernisations delayed her delivery until May 1956 and, to bridge the gap, the UK offered HMS Vengeance on loan. Sydney became a Fast Troop Transport and Vengeance was commissioned into the RAN as HMAS Vengeance. On her arrival in Australia she carried our first helicopter, the Bristol Sycamore.

The early years: Utility, Search and Rescue, Hydrographic

From the point of view of appeal and employability, the strengths of the helicopter have traditionally rested in its ability to hover, to take off and land vertically in relatively small and minimally prepared areas, to winch personnel and stores, and to carry equipment as an underslung load. Conversely, its weaknesses have been its slowness, its relatively short range, and its vulnerability to hostile fire. Consequently, in the early days, the effort directed towards the development of offensive weapon systems for fixed wing aircraft was not given to the humble helicopter.

Helicopters have, therefore, traditionally played a support role. Search and Rescue (SAR) has always been a task; however, this has often been reduced to purely rescue, with the search component being performed by fixed wing aircraft with their greater range and endurance. The ability to land in the grounds of, or very close to, hospitals makes it ideal for Medical Evacuation. Stores transfer, either by winch or underslung load, has likewise been a common helicopter task.

These, then, were the roles of the Bristol Sycamore, one of the earliest production helicopters, its first flight being 24 July 1947. It was sturdy and reliable, attributes proved with the British armed forces in various parts of the world, often in harsh and difficult conditions. The RAN operated 13: three Mk 50s and ten Mk 51s. The first batch were delivered aboard HMAS Vengeance, the second aboard HMAS Melbourne.

The helicopter performed well for its era, although it may now seem modest when compared with modem ones. Its Alvis Leonides 73 nine cylinder radial engine, of 550 horsepower, achieved a cruising speed of 90 knots (166 km/h) with a range of 285 nautical miles (527 km). It had a crew of two, carried three passengers or two stretchers, and weighed 5600 Ibs (2540 Kg) fully loaded.

Bell UH-lB Iroquois

The Iroquois, affectionately known as ‘the Huey’, is probably the most recognised helicopter in the world. Indeed, for some people it epitomises ‘the helicopter’. The powerful ‘thump’ of its rotor blades signals its approach from miles away and evokes visions of Vietnam newsreels for anyone old enough to have lived through the time. Several versions were built but the RAN operated the ‘Bravo’ model, although Navy aircrew flew other models in Vietnam, both with the RAAF and American forces.

During its RAN service, the Iroquois operated in the same roles as its predecessor but with an additional training role. It was, however, much more modem. Rather than the piston engine of the Sycamore, it was powered by the Lycoming T53-L-11 turboshaft, which delivered 1100 horsepower, exactly twice that of the Alvis. It had much the same performance figures but was heavier at 8500 Ibs (3856 Kg) gross weight. Although the ‘Huey’ did operate at sea on occasions, it was more commonly seen ashore, providing a continuation/transition training role for new navy helicopter pilots.

hu-1bwasp
The Huey UH-1B Iroquois (left) and Scout were the RAN’s first turbo-powered helicopters.

 Two light utility helicopters operated from HMAS Moresby, in support other hydrographic operations. The Westland Scout flew from the vessel from 1963 until 1973 until replaced by the Bell 206B (Kiowa). Both aircraft were employed ferrying personnel and equipment between the ship and shore camps.

The aircraft carrier provided the RAN with the capability to strike an enemy using fixed wing aircraft at greater ranges than would otherwise have been possible. However, it demanded an effective means of self-protection from submarines, a major threat at the time.

The effectiveness of the submarine had been well proven in World Wars I and II, and the USSR was now building up an incredibly large fleet of them. Anti-submarine warfare (ASW) was therefore afforded considerable importance. One of the more effective means of countering the submarine threat was the ‘dipping’ sonar equipped helicopter.


Westland Wessex 31A and 31B

The Wessex began life as the Sikorsky S-58. Westland built them under licence, replacing the original piston engine with a turboshaft (jet) and adding a dipping sonar and torpedoes. The Australian variant was the Mk 31 A, which was upgraded in 1969 to the Mk 3 IB. Normally, these aircraft were employed in pairs, in search sectors ahead of the carrier. They were very effective ASW helicopters and provided sterling service until 1975, when replaced by the Sea King.

wessex 31b
The Australian-converted Wessex 31B variant.

 The Sea King was also a licence-built Sikorsky. The design was changed to allow greater independence during operations, in line with RN philosophy rather then that of the USN, which preferred to maintain tighter control. The Australian model had more powerful engines and a six bladed tail rotor for operations in hotter climes.

Improved sonar and data link

The Sea King was equipped with a doppler radar navigation system, coupled to a large search radar display, providing accurate and reliable navigation information. This system also provided a means of controlling other helicopters to any desired position or to an accurate weapon release point. The doppler radar was also coupled to the aircraft flight control system enabling automatic transition from forward flight to the hover, providing a very safe and effective means of performing what is a potentially dangerous evolution at night or during bad weather.

The aircraft could carry two torpedoes; however, with its improved sonar and a datalink system it also had the alternative of transmitting sonar information to a ship which could then launch an Ikara torpedo-carrying missile. With an endurance on-station of four hours, the Sea King Mk 50 represented a considerable advance in helicopter anti-submarine operations.

sea kingseahawk
The Westland Sea King (left, photo LSPH K. Bristow) and Sikorsky S-70B-2 Seahawk proved to be highly proficient anti-submarine aircraft.

In addition to providing an improved ASW capability the Sea King also represented an important step in the development of the helicopter in Australian naval aviation, the additional role of surface surveillance. Previously undertaken by fixed wing aircraft, either land or carrier based, the Sea King’s four and a half hour transit endurance, navigation fit and radar enabled it to search many miles ahead of the carrier group. If two aircraft were used, stationed 80 miles apart and flying 200 miles down the group’s intended track, an impressive 40 000 square miles of ocean could be radar searched. These were early days, though, and the Sea King was never seriously utilised in this role.

Role development and the demise of the carrier

The early 1980s were not good years for the Fleet Air Arm. True, they began optimistically enough with Australia considering acquiring the British carrier, HMS Invincible. There was even some talk of buying the Harrier. However, the Falklands War caused the UK to rethink its decision to dispose of the vessel and an offer by the Australian government not to take her was quickly and gratefully accepted. Additionally, Melbourne‘s subsequent retirement in 1982 resulted in the retirement of the majority of its fixed wing aircraft. The decade that had started so promisingly had now suddenly crashed and burned. However, this event steered naval aviation down a different path and the next few years would see it rise, phoenix like, from the ashes.

The choice of the RAN’s next ASW helicopter had been discussed for several years. This was not a simple business of examining those helicopters currently ‘on the market’ that had the most impressive performance: the helicopter that could fly faster, longer, more economically and carry more torpedoes. Several other factors also had to be considered: which aircraft would be the cheapest and easiest to maintain, have the most potential for development over the period of its expected life, and provide most Australian industry involvement in manufacture and support. Several influences affected the selection process and it was far from simple.

Primarily ASW

It was accepted that the primary role of the helicopter would be ASW, but a fundamental consideration was whether to fit it with a dipping sonar or with sonobuoys and an acoustic processor. Each system has its advantages and disadvantages depending on whether the target is nuclear- or conventionally-powered.

Nuclear submarines were, during this period, becoming more common. The advantage enjoyed by a nuclear boat over its conventionally powered contemporary is its ability to stay below the surface for long periods and to travel at much faster speeds. A single dipping helicopter could not hope to achieve, let alone maintain, tracking information on a nuclear submarine: it would take two, sometimes three. Nuclear submarines were also noisy, being relatively easily detected by sonobuoys. Against the nuclear submarine threat, sonobuoys and an acoustic processor was the way to go.

On the other hand, conventional submarines, always considerably quieter than their nuclear contemporaries, were also now enjoying the advantage of advanced battery design. They could now go for periods measured in days, as opposed to hours (dependent on operating speed) before needing to re-charge their batteries. This allowed them to get into position ahead of a force of ships long before those ships arrived, a distinct advantage for the submarine captain. Previously, he had had to worry about charging his batteries prior to gaining a good attack position in order to ensure he had sufficient charge to make his escape.

This, of course, increased his vulnerability to detection. Now he could lie in wait well ahead of the force, confident that he could carry out his attack and still have ample charge remaining to creep away quietly. In this situation the dipping helicopter had the better chance of detecting the submarine than the sonobuoy equipped aircraft. Sonobuoys are ineffective against a conventional submarine that is lying in wait and making no noise at all, and they are little more so against one that is creeping quietly away making no more than two or three knots. Against conventional submarines, the dipping sonar tended to have the edge over the acoustic processor.

Small ship operations

A further factor to influence the choice of helicopter was the demise of the carrier. From 1982 onwards, the RAN would be operating its helicopters from ‘small’ ships: that is, vessels of about four to five thousand tonnes, compared with Melbourne at about 19,000 tonnes. Operating from a frigate, there would be less need, if any, for the screening operations so necessary with the carrier. Frigates were more likely to operate in pairs, or as part of a large force containing units from other countries. The days of the ‘escort force’ (aircraft carrier, supply vessel, escort destroyers and frigates) protecting a fleet of merchant ships, was considered a thing of the past.

In summary, the decision was taken to select a helicopter which could perform a broader range of tasks than the role dedicated aircraft of the previous era. The Sikorsky S-70B-2 Seahawk was selected but delivery would not be possible for some years.

The Squirrel was originally acquired in 1984 as an interim embarked helicopter for the FFG, really for the purpose of allowing the RAN to build up some experience in small ship embarked operations. The aircraft is a small, single engine civilian helicopter. It is fitted with skids, rather than wheels, and is not really designed for shipboard use. However, this little machine served brilliantly at sea, including operations during and after the Gulf War.

squirrel
The Aerospatiale Squirrel

 The body is largely constructed of composite material, earning it the nickname ‘plastic fantastic’; yet, this fact also made it extremely difficult to detect on radar. Although it had no detection equipment itself, other than the eyes of the crew, it was surprisingly effective at finding surface contacts. Furthermore, due to the ability and initiative of its crews, it could provide targeting information well within the acquisition parameters of the ship’s Harpoon missile. The Squirrel was probably the RAN’s first serious use of a helicopter for surveillance and targeting operations. Its most valuable contribution, however, was to provide experience for aircrews and ships’ crews in working together.

Gulf War

When called on to respond to the Gulf War, the RAN was able to provide three Squirrels and two Seahawks for immediate embarkation in three ships, fully confident in their collective ability to operate safely and efficiently together – which, of course, they did!

The S-70B-2 Seahawk is one of the most advanced ASW helicopters in the world. However, being a very flexible aircraft, it also performs well in the role of anti-shipping surveillance and targeting. It is powerful and fast and is capable of operating independently at extended ranges.

It can carry two ASW torpedoes and its role equipment includes radar, sonobuoy processor and a magnetic anomaly detector. A current update program will enhance the aircraft by adding an infrared detection system and an electronic protection system. The latter will provide warning against other radars and approaching missiles, and will initiate the dispensing of threat adaptive countermeasures. The Seahawk is a modern weapon system and an extremely capable asset. Yet, for all its attributes, the Australian version still does not provide a platform from which an anti-surface weapon can be launched.

seasprite
Kaman SH-2G(A) Super Seasprite.
 

The Kaman SH-2G(A) Super Seasprite is one step in the evolutionary journey of the Australian naval helicopter. Expected to enter naval service in 2005, it is a most sophisticated aircraft. Its primary role is to be Surface Warfare and it is equipped with an impressive assortment of sensors. These include: radar, with doppler based inverted synthetic aperture processing technique to enable discrimination and classification of small targets; an infrared detection system; an electronic protection system, including radar and missile warning and a threat adaptive countermeasures dispenser; and a data link communications system.

The Super Seasprite also carries the Kongsberg Penguin III guided missile making it the first Australian naval helicopter to have the capability to attack a surface target and inflict significant damage. This is an important development in Australian maritime warfare. The RAN again has the means of attacking an enemy ship while keeping its own ships at a safe range, and with its self defence systems the SH-2G(A) has a high probability of survival.

Conclusion

The last 50 years have seen the Australian naval helicopter progress through various stages of development to its current status as a maritime strike platform. The Sycamore and the ‘Huey’ fulfilled a utility role: providing rescue for downed fixed wing aircrew; delivering stores, equipment and personnel; and, of course, the continuation training role that every aircraft must perform.

The Wessex pioneered an era of the Australian naval helicopter as a true weapon system. Naturally, as with all helicopters, it was still called upon to perform the ‘traditional’ helicopter tasks, but it was also now called upon to contribute tactically in the ASW theatre. It could search and locate submarines, and more importantly, it could attack. The Sea King continued this trend, with increased accuracy and independence. It also introduced to the RAN the ability of the helicopter to operate independently, and to perform surface surveillance, although this was still in its infancy so far helicopters were concerned.

 The Squirrel and the Seahawk introduced the era of small ships’ flights operating from frigates and providing ‘over the horizon targeting’. The latest aircraft, the Super Seasprite, will provide the RAN with a platform which can search, locate and attack enemy ships with a high degree of accuracy and survivability. With such an impressive development, one wonders what the next 50 years will bring.