PETER GRAY / YEOVIL
With an uprated power plant and enhanced avionics, the revamped AgustaWestland Super Lynx 300 has a lot to offer both in shipborne and battlefield roles
The Westland Lynx first flew 31 years ago, entering service in 1976 in naval and army versions. Now, with over 20 variants and almost 400 aircraft sold, the helicopter is again being developed for shipborne and battlefield operations. As capability has increased over the years it has become evident the original Rolls-Royce Gem turboshafts could not keep pace, particularly with the demand for hot-and-high performance from potential customers.
The latest Super Lynx 300 is powered by the LHTEC CTS800-4N, which offers a vast improvement in power over the Gem 42-1. Not only does the CTS800 introduce a single-engine 30s power limit, rated at 1,210kW (1,620hp), it also produces an average of 36% more power at all settings, in single- and twin-engine operation. The CTS800 also consumes less fuel than the Gem. While the Gem has an integral reduction gearbox to reduce shaft speeds and the CTS800 does not, meaning one had to be designed and incorporated, power-to-weight ratio is nevertheless impressive.
In addition to strengthening the main gearbox to take the additional torque, AgustaWestland's UK arm Westland Helicopters has upgraded the aircraft in other ways, increasing the airframe life from 7,000h to 10,000h, and maximum take-off weight from 4,425kg (9,730lb) to 5,330kg. The other major change is a glass cockpit to reduce crew workload and integrate systems, including those managed by the observer/tactical operator in the left-hand seat. Many of the design features have come from experience with the AgustaWestland EH101.
As with earlier Lynxes, the upgraded machine is flexible enough to carry out roles including anti-submarine and anti-surface warfare, over-the-horizon targeting, vessel replenishment, maritime patrol, search and rescue, armed attack, transport and even crop spraying, says Westland. The Super Lynx is designed to be a multirole helicopter and role changes have been made as rapid as possible, in most cases taking less than 40min.
Although the Super Lynx 300 is still under development, Flight International was invited to evaluate one of the two test aircraft. While one is a testbed for the engine, the aircraft we flew is being used to develop the avionics and is equipped with the new glass cockpit. Destined for the Royal Malaysian Navy, it is intended to operate from ship-decks so the two rear wheels are offset, there are no brakes and the helicopter cannot be taxied or perform running landings. The oleos can be locked to prevent movement when parked on a heaving deck.
Two flights were made with chief test pilot Colin Hague, who has been involved with the Lynx since its inception. For the first flight weather was poor, with a low cloudbase and visibility preventing proper evaluation of the aircraft in forward flight. But we were able to get airborne and cover all the hover manoeuvres, while flight-test engineer John Doherty was able to demonstrate some of the radar, forward-looking infrared (FLIR) and other features. Test programme restrictions limited the maximum take-off weight to 4,875kg and there were limits on the amount of power that could be pulled.
This is a functional rather than pretty aircraft. The stepped nose mounts the FLIR and 360° scan radar. The pitot head is at the front. Its design makes the airspeed indicator start from zero, unusual in a helicopter where the indicator normally shows only at higher airspeeds. The vertical speed indicator, being electrically powered, also gives an instant and accurate reading of climb/descent rate - useful for instrument flying.
This aircraft has an ice accretion indicator on the fuselage, visible to the pilot. The helicopter performs well in moderate icing conditions, Hague says, but only the engine intakes and pitot head are anti-iced.
Fixed fittings for the electrically powered winch fold away inside the cabin to reduce drag. Large sliding cabin doors allow easy installation of stretchers and other equipment. In a heavy landing, forces are absorbed by the undercarriage and belly. Crash attenuator seats are an optional extra.
The helicopter's most notable feature on the head is the shape of its main rotor blades, with their distinctive paddle-tips, designed to help combat the limitations of high-speed forward flight. The rotor hub is semi-rigid, which gives crisp handling, but probably a harder ride. Vibrations are suppressed by an absorber on the rotor head. For shipboard stowage, the rotor blades and tail can be folded. The fin is offset slightly to offload the tailrotor.
The right-hand pilot's seat was comfortable, although adjustment is limited to backwards and forwards - the pedals likewise. The outstanding impression is of simplicity in cockpit layout. Two Smiths Aerospace colour liquid-crystal displays (LCD) - called integrated display units by Westland - directly in front of the pilot contain essential flight and navigation information, plus whatever else is needed, such as a moving map or target data. The displays are interchangeable, so if one fails, the information is available on the other. Usually glass cockpits have three "get-home" standby instruments located out of the pilot's normal field of vision. In a welcome move, Westland has incorporated everything on to one instrument in the pilot's line of sight.
When Flight International flew the EH101, it criticised the use of strip gauges to indicate, for example, vertical speed. They occupy less space than conventional round dials, but the rate of change is harder to interpret and they all look the same. The essential flight instruments on the Super Lynx displays are round dials. Between the four LCDs are two flat-panel displays which show system parameters, fuel state and so on. The fuel system manages itself, simply providing the crew with a presentation of what is where.
The centre lower console contains two more side-by-side LCDs, part of the control display navigation units. The many radio combinations are managed from just one location. All the displays are surrounded by bezel-mounted buttons allowing the crew to select the information required.
Because the engines are digitally controlled, there are no throttles or manual speed selects, reducing cockpit clutter. Instead there is a simple engine management panel overhead with a twist knob for each engine with "stop", "ground idle" and "flight" settings. Ground power plugs into the left-hand side of the aircraft, out of pilot sight. There is no warning light, but if ground power is still plugged in, the aircraft battery will not come on line.
Hague, beginning overhead, set up the aircraft for the start without using the checklist, which can take several minutes to read. It was quick and efficient thanks to the clean layout. He selected "ground idle" and a cool, slow start followed. Starting the number one engine first brings on most accessories, such as hydraulic power to check the controls, but the blades do not turn. After some additional checks, the number two engine was started and the rotor wound up to 104%, where it stays throughout normal flight. In a hurry, both engines can be started in "flight".
Semi-rigid rotors are crisp to handle, but can cause pilot-induced oscillations. Having experienced this with the EH101, I relaxed before pulling up into the first hover and had no problems, being able to maintain an accurate and steady hover with minimal input. A glance at the instrument panel showed immediately how much power was being used and, importantly, how much was still in hand.
With only 5-10kt (9-18km/h) of wind, it was impossible to establish how the aircraft handles in stronger winds, but Hague says there are no difficult hover sectors. This will help when the task places the pilot out of wind.
With the aircraft trimmed out and controls released, the helicopter stayed more or less over the spot. Auto-hover will be available. Flying sideways and backwards to the proposed limits of 40kt showed there was still plenty of tailrotor pedal available, again a comfort to the pilot. Spot turns presented no problems, but Hague demonstrated the maximum 60°/s rate of turn in both directions. The ample tail-rotor control power was evident from this impressive demonstration, during which the horizon became a blur and sideways g could be felt.
The dual-channel automatic stabilisation equipment directly drives the control servos, unlike in other helicopters, where the inputs go to a mixing unit. While in the hover, Hague disengaged the system. I was able to continue an accurate hover with little extra effort. He then switched off the number one hydraulic system while in the hover.
Although there are two hydraulic systems (plus a hydraulic pump for dipping sonar on some machines), only the number one system powers tailrotor pitch change. Its loss also affects the collective lever, which immediately stiffened up, as did the pedals. However, I was able to maintain a fairly accurate hover and land.
While Hague held the aircraft in the hover, Doherty demonstrated the FLIR, radar and map/navigation facilities. The sensors will track a moving target, even one behind the aircraft, Doherty using a small joystick for this task. The FLIR's wide field-of-view and zoom capability are impressive, the navigation facilities of the highest order and the systems was well integrated and relatively simple to operate. Presentations offered to the crew are excellent.
We ran through malfunctions, such as generator failure and an engine fire drill, the only emergency that requires instant action. The fire presentation and subsequent actions are carefully designed to prevent shutting down a good engine. For simplicity, Westland has reduced the aural warnings to two, alerting the pilot that a red capsule has illuminated and the aircraft is at low level. In some helicopters, the multiplicity of aural warnings can be confusing to the pilot.
For the second flight, two weeks later, the weather was excellent, almost a standard-atmosphere day. Hague demonstrated a typical operational pilot's pre-flight inspection. This does not include opening any panels, but there are sufficient sight glasses, steps and handholds to see everything necessary and the procedure took just a few minutes.
Installed again in the pilot's right-hand seat, the airspeed indicator started to flicker after take-off as soon as we transitioned into forward flight. It burst into life at about 10kt. How accurate it is at this low speed is not known.
We levelled out at 2,000ft (600m), weight again restricted to 465kg below maximum. Pulling 100% torque, well below maximum continuous power, produced the normal maximum operating speed (Vno) of 150kt. Vno is 10% below the unpublished "never exceed" speed (Vne) of 165kt, but flight testing will take the Super Lynx to 10% beyond Vne -182kt - to ensure that no pilot will experience any control problems at high speed.
Vibration suppression is good, with no increase in the benign vibration levels at 150kt. Despite the aircraft's utilitarian appearance, it will cruise quite happily at 140kt and could cruise at 150kt if required, although fuel consumption and range would be affected. Rolling left to right to the sustained steep-turn limit of 45° and the transient limit of 60° at this weight and Vno there was no increase of vibration. Visibility into the steep turns is excellent.
Settling into a casual cruise of 120kt, Hague pulled back an engine to ground idle. There was a momentary loss of 1% rotor RPM, which then restored itself, and the relevant LCDs converted to single-engine power presentation. The cruise continued at 120kt.
While in the cruise, Hague lowered and raised the collective lever quickly, with and without the automatic stabilisation equipment (ASE) engaged. Rotor RPM fluctuated ±1% and attitude changed ±1°, a satisfying conclusion for a pilot in difficulties. Full ASE provides a hands-off aircraft ready to accept any pilot inputs. For example, height hold can be governed by barometric or radar altimeter.
After all this non-excitement, I turned, descended, climbed and generally enjoyed the countryside. The aircraft handles excellently, helped considerably by the transparent ASE. But even without stabilisation, the helicopter is docile. Without the ASE, Hague trimmed the aircraft for straight and level flight and took hands and feet off the controls. For a few seconds we flew on with no attitude change, then slowly waffled. This was at 80kt. Some helicopters in this situation will immediately go divergent, but not the Super Lynx.
Hague then demonstrated a positive g pull-up followed by a negative g pushover. The limits are quite modest, but again flight testing will ensure there are adequate buffer boundaries to protect the occupants should they inadvertently exceed them.
As we returned to Yeovil, Hague took out the number one hydraulics. In cruise flight there is hardly any difference in control feel. I elected for a flat approach with minimum inputs on the lever and pedal, the controls affected by the loss of hydraulics. I came to an accurate hover, held it, and settled gracefully on the grass.
Probably out of relief, and because the lever was stiff to move, I pushed it hard down to ensure the aircraft did not move. The rotor went into negative pitch and the engines spooled up. This is what happens when the Lynx lands on a moving ship - move the collective lever into the negative pitch range and 2,000kg of rotor downforce anchors the helicopter to the deck until the deck-lock harpoon engages.
The flight was completed with a circuit and very steep approach to a designated spot. Hague says the aircraft has never shown signs of vortex ring/settling with power, but nevertheless I restrained the low-speed steep approach to modest rates of descent, and the nose had to be yawed fairly hard to the left to get a good view of the intended landing spot. A vertical climb to 100ft and back produced no visibility problems. Hague completed the flight by roaring down the runway at high speed and pulling up to a vertical climb and graceful "wing over".
Compared with other helicopters I have flown, the Super Lynx is crew friendly. For a relatively small aircraft, it is packed with sophisticated, user-friendly equipment. The aircraft is a delight to handle and the automatic stabilisation, hydraulic and trim systems are well integrated.
The Super Lynx 300 is aimed at the intermediate maritime and multirole military helicopter markets. So far, eight naval and 16 battlefield helicopters have been ordered. Primary target areas are Asia, the Middle East and South America. The price depends on the equipment fitted, but in recent competitions the helicopter has been priced competitively against its main rivals, the Eurocopter AS565 Panther and Kaman SH-3G Super Seasprite, according to Westland.
Source: Flight International