Winner: Eurocopter
Location: Paris, France
Achievement: Application of advanced noise-reduction technologies throughout the design of the low-noise EC 135 helicopter
THE AWARDS JUDGES decided that two entries in this year's Helicopters category stood out "head and shoulders" above the others. Those were from Eurocopter for the twin-engined EC 135 and McDonnell Douglas Helicopter Systems for its Longbow Apache.
Eurocopter was eventually chosen as winner for its work on making substantial cuts in the overall noise emissions on the EC 135 through use of advanced technologies. The Awards judges were impressed by the consistent application of noise-reduction techniques throughout the aircraft's design.
Noise emissions from the seven-place helicopter are well below the new limits set by the International Civil Aviation Organisation.
The aircraft's main rotor system is completely hingeless and bearingless, and was developed by Eurocopter Deutschland with the support of the German Ministry of Research and Technology.
The traditional rotor head has been eliminated. Its replacement has four aerodynamically optimised composite rotor blades, and features an integrated glass-fibre-composite flexbeam and control cuff, and a rotor shaft with blade attachment flange, which is a one-piece forging.
Hub components used in conventional systems, such as centrifugal force transmission elements, bearings and bearing sleeves, were eliminated and replaced by the flexbeam. The main rotor has no flap and lag hinges, as their functions are eliminated by stiffness tuning in the flexbeam.
The "Fenestron"-type shrouded tail fan was developed by Eurocopter France, and was selected to promote operating safety on the ground and protection against foreign-object damage in flight. It features an advanced configuration with improved aerodynamics, reduced noise, increased life-cycle and reduced operating costs.
To reduce noise levels further, unequal spacing of the rotor blades was introduced, resulting in a "phase-modulation" effect. The tail rotor and the bearingless main rotor feature variable rotor speeds to control noise levels at low altitudes and during take-off and landing.
Light-weight Kevlar/carbon-fibre composite components are used extensively throughout the airframe, accounting for 54% of the total weight, also reducing risk of corrosion.
The EC 135 is the first helicopter in the world to be simultaneously certificated with two engine types - the Turbom‚ca Arrius-2B and Pratt & Whitney Canada PW206B. Both engines include full-authority digital engine control devices to ensure the continuous optimisation of the engines, and the automatic adjustment of the rotor system to minimise noise emissions.
The aircraft also has a passive anti-resonance isolation system to minimise vibrations within the passenger cabin.
Finalist: McDonnell Douglas Helicopter Systems
Location: Mesa, Arizona, USA.
Achievement: Enhanced performance of the latest AH-64D Longbow Apache, which completed tough US Army education trials.
The McDonnell Douglas Helicopter Systems (MDHS) AH-64D Longbow Apache attack helicopter underwent a series of US Army gruelling trials in the first three months of 1995 which revealed just how far this new version had come from the baseline AH-64A.
The aircraft's performance proved exceptional. In the words of one of the Flight International Awards judges, the latest AH-64D is simply a "very impressive machine".
The US Army's Initial Operational Test and Evaluation (IOTE) programme ran at Fort Hunter-Liggett, California, until the end of March 1995. The operational tests pitted basleine AH-64A and modernised AH-64D Longbow Apaches against "advanced armour and air-defence threats" says MDHS. Army data show that the Longbow Apache is "six times more lethal and four times more survivable" than the AH-64A.
Although most IOTE data remain classified, unofficial US Army information suggests that other aspects of the Longbow Apache's performance during the field evaluation more than met expectations.
It was also noted that during the trials, all AH-64D "losses" occurred during the first half of the "force on force" phase, suggesting that pilots quickly learned how to use the new systems and refine their tactics.
MDHS maintains that the success of the AH-64D during the IOTE directly influenced the decisions of the UK and Dutch Governments to become the first international customers for the AH-64D Longbow Apache. These competitions were both strongly contested by Eurocopter, with the Tiger, and in the case of the UK also by the Bell Helicopter/GEC team, offering the Cobra Venom.
The IOTE was the culmination of a 70-month Army and industry engineering and manufacturing development programme designed to modernise the Apache.
This programme was focused on improving target acquisition, situational awareness, battle management, attack co-ordination and firepower functions.
Over the past decade, the aircraft has been heavily modified with advanced weapons, communications devices and sensors, to support the demanding needs of the digital battlefield.
The AH-64D is a fully integrated digital-weapon system which significantly increases mission effectiveness, day or night and in most weather conditions. The aircraft's avionics and electronics, including the Longbow fire-control radar system, which have led to its selection by the US Army were crucial in the decisions made by the Netherlands and the UK.
Source: Flight International
