Seasprite v Lynx the Battle of the Navy Helos

Kaman studied offering both intermeshing main rotor and conventional helicopter designs to meet the requirement. A conventional single main rotor configuration was selected for higher speed performance and to cut down on required deck space. Other design features were a single General Electric T58 turboshaft, a top speed over 140kt (260km/h), a comprehensive IFR instrument suite for bad weather flight and Kaman’s trademark servo flaps on the main rotor blades which give stability in poor weather.

The prototype Seasprite first flew in June 1959 and deliveries of production UH-2As began in December 1962. Some 190 were built through to the mid 1960s and several saw service in Vietnam providing SAR coverage.

Meanwhile the UH-2’s good speed also impressed the US Army, who for a time planned to order an armed development of the Seasprite designated the H-2 Tomahawk as an interim helicopter gunship. It would have featured two miniguns in the nose, a roof mounted sight and stub wings for rockets and other stores.

To improve power and survivability on combat SAR missions the Seasprite gained a second T58 engine. A UH-2 was modified with a second T58 in March 1965, while the prototype twin engined UH-2C Seasprite first flew the following year. Six armed and armoured HH-2Cs were built in addition to 67 unarmoured standard configuration HH-2Cs.

The H-2 was later selected as the basis for the US Navy’s LAMPS (Light Airborne Multi-Purpose System) frigate based anti submarine warfare helicopter in October 1970. Twenty Seasprites were originally converted to LAMPS I SH-2D configuration fitted with a Litton search radar, removable sonobuoy launcher and a towed MAD (magnetic anomaly detector) bird carried on the starboard fuselage pylon.

From May 1973 Kaman converted 88 Seasprites (almost all surviving UH-2s and SH-2D airframes) to SH-2F standard, fitted with uprated engines, a Canadian Marconi search radar and a towed MAD. In addition, at the US Navy’s request, Kaman reopened the Seasprite production line in the early 1980s to build an additional 54 SH-2Fs.

SH-2Fs flew in the Persian Gulf extensively during the Iran/Iraq War during the 1980s, while SH-2Fs also served from US warships during the Gulf War, providing important tactical situation information by flying anti ship surveillance and targeting and mine hunting missions. The last US Navy SH-2Fs were retired in 1994.

The latest version of the Seasprite is the SH-2G Super Seasprite, which is currently in service with two US Navy Reserves squadrons. It is on this aircraft that Kaman’s offering to Australia, the SH-2G(A), is based.

The SH-2G was developed from the mid 1980s as a result of the US Navy’s decision to keep its Knox class frigates in service through to 2015. Rather than refit the Knox ships with a strengthened flightdeck to handle the heavier Sikorsky Seahawk, which was ruled out on cost grounds, the US Navy instead elected to upgrade the Seasprite to provide the ships with an advanced ASW helicopter.

What resulted was essentially an all new helicopter in the Seasprite’s basic shell, with $US500m spent on development. Most obvious of the changes was the new engine selection, two General Electric T700-GE-401 turboshafts, each generating 1723shp (1285kW), giving impressive power reserves and true single engine performance. They offer 30% more power than the SH-2F’s T58s for the same max takeoff weight and also increase the mission time through improved fuel consumption (20% better than the T58). With the new engines came a new transmission, which features a demonstrated 30 minute oil out operating capability.

Apart from the engines, the Super Seasprite gained a new avionics suite built around a MIL STD 1553B databus including a 99 channel UYS-503 acoustic processor, although cockpit displays are conventional rather than glass and the radar remained the LN-66 as on the SH-2F.

Kaman says that when it was redesigning the Seasprite it was able to incorporate the lessons the US Navy had learned with the Seahawk program into its aircraft. A full scale fatigue test confirmed the Super Seasprite had a guaranteed 10,000 hour service life, with the potential for a further 10,000 hours.

The prototype YSH-2G first flew in April 1985. Six new build SH-2Gs were subsequently delivered in the early 1990s, followed by 18 remanufactured SH-2Fs. The US Navy’s plans for a large fleet of Super Seasprites to equip Knox class frigates were dashed when funding cuts forced the early retirement of that class of ship. This left the US Navy with two Reserve squadrons of Super Seasprites to fly off older Oliver Hazard Perry Class (FFG class) frigates which are not equipped with the RAST recovery system and so cannot embark Seahawks, and other small deck ships.

The US Navy’s move not to upgrade further SH-2Fs to SH-2G standard opened the door for Kaman to pursue export opportunities with the upgraded Seasprite, taking advantage of its ability to rebuild ex US Navy SH-2Fs currently in storage at the Davis Monthan Air Force Base in the Arizona desert to as new condition.

Kaman’s first export success came with Egypt’s order for 10 remanufactured SH-2Gs fitted with an AlliedSignal AQS-18 dipping sonar. Current sales interest lies with supplying naval helicopters for Australia, New Zealand and Malaysia.

For the Australian competition Kaman has developed the SH-2G(A), which is based on the basic Super Seasprite but with a number of changes to meet the RAN’s specifications. The biggest and most important change is the two crew cockpit and the ITAS – Integrated Tactical Avionics System. The ITAS is being designed and developed by Litton and features four large colour multifunction displays – two for each crew member – presenting aircraft and sensor information, plus HOCAS (hands on collective and stick) controls for the pilot and automated data processing, all linked via the 1553B databus.

Kaman recognises that the two crew requirement is the most demanding of the RAN’s specification and, through Litton in particular, is expending considerable resources on this area of its bid. Kaman points out that with the engine and airframe unchanged from the SH-2G, it can focus its efforts on this area of the aircraft. If Kaman is selected it will work with RAN flightcrews to finalise the layout of the centre console so it is laid out specifically how the crews like it.

Other key requirements of the bid are the radar and weapon system. Kaman has a base specification it is proposing against the bid, while at the same time saying it is prepared to mix and match the radar, weapons, Flir and ESM system should the RAN request a different system to Kaman’s proposal.

Kaman’s SH-2G(A) as it currently stands would be fitted with the Telephonics APS-143 radar and Hughes AAQ-16 Flir and would be armed with the Kongsberg Penguin ASM.

Kaman is also offering the Seasprite with GE T700-GE-401C turboshafts, the slightly more powerful variant of the T700 which powers the Seahawk and Black Hawk, thus offering commonality with Australia’s large S-70 fleet. Also offered to the RAN as an option are composite main blades in place of the Seasprite’s standard aluminium spar and glass honeycomb units. Benefits would include a 15,000hr fatigue life and improved damaged resistance and easier repairability.

Kaman has extensive experience with composite blades, having designed and then built more than 500 for the US Army’s AH-1S Cobra attack helicopters. A composite blade equipped SH-2G first flew last July.

Kaman originally proposed rebuilding ex US Navy SH-2Fs to meet the RAN requirement, however, at the Navy’s request, the company is now offering completely new build aircraft as an option as well. New build helicopters have also been offered to New Zealand (New Zealand was originally planning to announce its selection of the helicopter for its Anzac and Leander frigates last April, however this decision has been deferred and had not been announced at the time of writing).

Kaman’s partners on its Australian Seasprite bid comprises avionics supplier Litton, engine manufacturer General Electric, Transfield who has project management and ship/aircraft integration responsibilities (Transfield builds the Anzac frigates at Williamstown in Melbourne), Safe Air of New Zealand who will assemble any Australian (and New Zealand) SH-2Gs and also perform aircraft maintenance and overhaul, SMA with responsibility for logistics analysis, training and documentation and supply support, and CSC, in charge of systems engineering, software development and support design, manufacture and support of the training system.

In addition, Kaman has pledged that, should it win further international Seasprite orders in addition to an Australian order, Safe Air would undertake final assembly as part of its efforts to fulfil Australian Industry Involvement commitments (contractors are free to place work with Australian or New Zealand companies to meet AII requirements).

The production schedule for the SH-2G(A) if Kaman is awarded the RAN contract would see a first flight in October 1998, missile testing in April 1999 and final acceptance by the Navy in October 2000.

Westland Super Lynx

The Lynx dates back to the late 1960s when Westland was working on its WG.13 design for a ship based naval helicopter for the Royal Navy.

The WG.13 was one of three helicopter designs covered by the 1967 Anglo/French helicopter production deal, the others being the Aerospatiale Gazelle and Puma. Under this deal the British bought French built Pumas and Gazelles (with some British production content) and the French Navy ordered Westland built Lynxes (as the WG.13 had become), with Aerospatiale (now Eurocopter) responsible for 30% of Lynx production.

The first of 13 prototype Lynxes flew for the first time on March 21 1971, while the first Lynx HAS.2 for the Royal Navy had its first flight in February 1976.

The Lynx was designed from the outset for operations from small and medium sized naval vessels. Design requirements were for a two crew, twin engine helicopter for a number of roles, primarily anti submarine warfare and anti surface warfare. The new helicopter needed to be manoeuvrable, able to operate from ship decks in high sea states and winds and have advanced deck handling characteristics.

Lynx design characteristics include the forged titanium main rotor hub, key to the manoeuvrability, and outward facing main undercarriage legs for good on deck manoeuvrability. The Lynx is able to turn around 360° on deck allowing it to launch and recover independent of the ship’s heading (ie the ship does not have turn into the wind to launch the helicopter) and can launch and land in winds up to 55kt (102km/h). Another Lynx feature is that the downward main rotor thrust can safely hold the helicopter on the ship’s deck until it is secured. The constant ride height undercarriage allows safe rearming and refuelling while the rotors are running.

The folding tail and main rotor minimises the hangar space needed to accommodate the Lynx, an important consideration on smaller vessels. Power was from two Rolls-Royce Gem turboshafts.

The Royal Navy’s Lynx HAS.2, with Ferranti Seaspray radar and dunking sonar, was followed by the HAS.3 which introduced uprated Gem 42-1 turboshafts and an improved GEC-Marconi Seaspray radar. Most export Lynx have been of a similar standard to the HAS.2 or HAS.3. Operators include France, Germany, Brazil, Denmark, the Netherlands, Nigeria, Pakistan and Norway.

The Lynx was also selected by the British Army for use as a battlefield transport and anti tank attack helicopter. While the Lynx was designed from the outset for naval missions the British Army was attracted to the helicopter by its excellent manoeuvrability and large cabin. The three British Army Lynx models are the initial AH.1, the upgraded AH.7 and the AH.9 with wheel undercarriage rather than skids and the composite main rotor blade. AH.1s and AH.7s have been armed with TOW anti tank missiles for the anti armour role (in fact the AH.7’s anti armour role is to be taken over by Westland built WAH-64D Apaches).

The Royal Navy’s current standard Lynx is the HAS.8. The HAS.8 introduced composite main rotor blades with swept tips (for improved speed and aerodynamic efficiency), further uprated engines, improved ESM and a nose mounted GEC Sea Owl thermal imager. The tail rotor on the HAS.8 also turns in the reverse direction. The HAS.8 also features the Racal RAMS 4000 central tactical system which processes sensor data and presents it on a multifunction CRT display.

A lack of funding meant the RN had to drop plans to fit the HAS.8 with a 360° coverage Seaspray radar and a rear mounted internal MAD (magnetic anomaly detector). The RN intends to operate its Lynx HAS.8s through to 2020.

The export Super Lynx is based on the HAS.8 and so far has sold to South Korea and Portugal. New Zealand is being offered a Lynx to a similar standard to the HAS.8/Super Lynx. A New Zealand Lynx would feature the Seaspray 3000 radar and the GEC multirole turret.

The RAN Super Lynx is based upon the HAS.8/Super Lynx but is another generational improvement with several major enhancements to the engines, avionics and sensors.

The engines for the RAN Super Lynx are two LHTEC (Light Helicopter Turbine Engine Company) CTS800 turboshafts. The CTS800 is the commercial version of the T800, an all new engine developed by a teaming of Allison and AlliedSignal which will power the US Army’s Sikorsky/Boeing RAH-66 Comanche reconnaissance helicopter. It received US Army Qualification and US FAA civil certification in 1993. Compared with the Gem it replaces, the CTS800 offers significantly improved fuel consumption, reliability, improved spool up times, better engine out performance and greater power reserves for operations in hot and high conditions.

Westland is currently working on the qualification of the Lynx with the CTS800, although a CTS800 powered Lynx first flew back in September 1991, with flight testing continuing into 1992. With this experience behind it Westland expects few problems in integrating and qualifying the new engine/airframe combination.

Westland is offering the Lynx to the RAN with two radar options – the GEC Blue Kestrel 6500 which has been developed for the Royal Navy’s EH 101 Merlin, and the Israeli Elta 2022, which has also been selected as the radar for the RAAF’s AP-3 Orion upgrade, and thus would offer commonality benefits, and is offering the GEC Sky Guardian and Electronica ESM suites and the BAeA Flir with the GEC multirole turret as an option.

Westland’s missile options for the RAN Super Lynx are the British Aerospace Improved Sea Skua, with the Italian OTO Melara Marte Mk 2 (which has been developed for the NH 90) offered as an option. Westland ruled out offering the Kongsberg Penguin due to its size and the Hughes Maverick as it is rail launched, with problems including launch height and speed restrictions and possible problems with the missile’s exhaust plume and heat as it passed the sensitive nose and radar section of the helicopter.

An Australian Lynx would be the first Lynx with a glass cockpit. Westland’s cockpit design for the Lynx is based on its experience with the EH 101 and is built around four colour multifunction displays, with two smaller displays for the engines and ancillaries, and two control/display units, one each for the pilot and tacco.

The cockpit displays are the front end of the Lynx’s Tactical Processor and Display System, which is designed for automated processing, fusion and presentation of data from the Lynx’s sensor suite and information sent via datalink from the home ship and other defence platforms. The digital avionics system is built on a dual redundant MIL STD 1553B databus.

Westland’s partners in its RAN Super Lynx bid are British Aerospace Australia (BAeA and AWADI were both partners in their own rights before the former’s acquisition of the latter) and Air New Zealand Engineering Services.

Should the RAN select the Lynx, BAeA would undertake final assembly, perform in service maintenance, support the Sea Skua missile (if it is selected), support the TPDS software, undertake aircrew and maintenance crew training, provide and maintain the Operational Flight Trainer, and support some selected avionics systems.

Air New Zealand Engineering Services would have responsibility for the maintenance and repair of the engines and some dynamic components, provide inventory management services, and build ground support and special to type equipment.

Westland also plans to establish a Helicopter Design Centre in Sydney which would act as a coordinating body for the Westland led team’s activity, provide the RAN with a single point of contact, and be a management centre for maintenance, any design changes, inventory management and training.

Conclusion

In some ways the Seasprite and Lynx are quite different aircraft – the American Seasprite is big and powerful, the British Lynx is smaller and agile. However, more likely to have a strong influence on the Navy’s final decision is the sensor suite, ESM and weapon offered, and how all the data from these systems is collated and presented to the two crew members.

If all goes to schedule the RAN should select the winning tender for the Anzac helicopter project by year’s end, with service entry in 2000. Whatever aircraft is selected, the RAN’s demanding project specifications should see it ending up with the most capable intermediate surveillance and anti ship helicopter that can be developed, short of an all new aircraft.