NAG Library Algorithms Provide Numerics for Helicopter Design & Analysis

Aerospace Case Study

NAG Library Algorithms Provide Numerics for Helicopter Design & Analysis

Case Study Background

Leonardo SpA, formerly known as Finmeccanica is an Italian multinational company specialising in aerospace, defence and security. Centred in Rome, it is located at 180 sites worldwide. The company is organised into the divisions: Helicopters, Aircraft, Aerostructures, Electronics, Security and Information Systems.

The Helicopters division is based on the former independent companies Agusta and Westland. It performs research, design, development, production, customer support, pilot training and marketing of the company’s extensive range of modern helicopters for the commercial, public service, and security and defence markets. The plants are physically located in Italy, the UK, Poland and the US.

Requirement – flexible, compatible and tested numerical routines

The Helicopter Division endeavours to constantly expand the capability and performance of its products, and to integrate the latest technology into its programmes, creating, through research and development, a modern and technologically advanced range of rotorcraft. Because of this Leonardo continually invest in advanced computer software. Although some of the company’s work utilises proprietary software, for example, in the areas of computational fluid dynamics or finite difference methods, because of its unique requirements it has been necessary to develop its own numerical code for the design, analysis and modelling of helicopter behaviour. Much of the code is written in Fortran, in conjunction with Unix scripts, and currently there are several hundred programs consisting of the order of 3 million lines of code, created and developed by both engineers and IT specialists, often by multiple contributors in parallel or sequentially over time.

Solution – calling on NAG Library numerical routines into existing software

The software is complex and often ground breaking. With this in mind, and to avoid re-inventing the wheel, the program developers access, with complete confidence, a large library of routines that offer a wide range of numerical and statistical routines. Leonardo Helicopters’ internally-developed code calls NAG Library routines for the following tasks:

  • Manipulating matrices: required commonly throughout the programs. These are often simple operations such as multiplication or inversion, the need for matrix handling being due to many tasks requiring simultaneous calculations to determine the effects of forces and moments working in and around the x-, y- and z-axes. However, there are also requirements to provide specific tasks such as
    • solution of simultaneous linear equations;
    • calculation of eigenvalues and eigenvectors, particularly when determining envelopes;
  • Locating zeros of polynomials and continuous functions, as a sub-task within larger algorithms;
  • Solving simple ordinary and partial differential equations;
  • Applying the Fourier transform or its inverse to a discretised signal. This is particularly important in noise and electrical analysis, where it is common to translate signals between time and frequency domains before analysis;
  • Interpolation;
  • Linear regression;
  • Curve and surface fitting;
  • Curve and surface smoothing;
  • Sorting or ranking vectors or rows or columns of matrices.
BERP blade on AW101

Conclusion – NAG delivers major benefits to Leonardo through the NAG Library

Much of the code developed by Leonardo Helicopters’ in-house team is written specifically for analysing helicopter behaviour, and therefore requires specialist knowledge in designing algorithms and code. This process is greatly assisted by accessing NAG Library routines which, due to their longstanding widespread use throughout industry, the team place full confidence in. Because of the precise and detailed specification of the NAG Library over a range of areas, they can apply the routines to all aspects of the design and analysis process across each aircraft in the extensive range of helicopters described below. This is a major benefit to Leonardo.

Software Application Detail

Some of the tasks tackled by this software are:

  • Designing helicopter airframes;
  • Predicting and analysing airloads and moments;
  • Designing helicopter rotors and rotor blades, including the revolutionary BERP blade which has been designed and manufactured at Westland Helicopters;
  • Predicting and analysing aerodynamic performance;
  • Predicting and analysing aeroacoustic behaviour, i.e. the noise, heard on the ground, which is created by the interaction of each rotor blade with the air and wakes of the other blades on the rotor;
  • Predicting and analysing vibratory noise, i.e. the noise, heard inside the aircraft, which is generated by vibration of the airframe;
  • Predicting and analysing stress across the aircraft;
  • Predicting and analysing envelopes or limits which can be borne by the aircraft;
  • Examining the effects of electrical units and their corresponding interference;
  • Preparing input data for use in proprietary software packages;
  • Analysing results produced by proprietary software packages.

More about Leonardo Helicopters

Aircraft produced by the company include:

  • Korea Navy AW159 in anti-submarine role
    AW101 combining the most advanced technologies, safety by design, mission systems and leading-edge manufacturing, provides a proven multi-role platform for combat search and rescue, search and rescue, utility and troop transport, amphibious lift, anti-submarine and anti-surface vessel roles, as well as Heads of State and VVIP operators;
  • AW119 is the most spacious and powerful light single-engine helicopter for a wide range of missions;
  • AW139 is a new-generation intermediate twin-engine helicopter employed worldwide in challenging operations in multi-mission applications. A military variant also exists;
  • AW149 is the latest generation medium category helicopter designed to provide versatile battlefield support;
  • AW159 is the latest-generation multi-role, military helicopter, designed from concept to operate in the harshest maritime environments of high sea state and associated deck motion conditions. With its advanced avionics, tactical processor and powerful sensors, it provides the crew with excellent tactical awareness and the ability to quickly locate and identify targets, be they naval or land based. The AW159 is an evolution of the highly successful, battle-proven Lynx in operation with 15 nations. Designed and built in Yeovil, the twin engine AW159/Lynx primarily serves anti-submarine and surface vessel roles as well as search and rescue, battlefield utility and anti-armour. The Lynx still holds the official world helicopter airspeed record;
  • AW169 is the latest-generation 4.6 tonnes twin-turbine helicopter, featuring class-leading performance for versatile capability in the most demanding operating conditions. A military variant also exists;
  • AW189 is the latest-generation, high performance 8.3 tonne twin-engine helicopter, providing a versatile, affordable, multirole platform;
  • GrandNew is the premium light twin helicopter, enhanced with the latest global navigation satellite system for all weather operations;
  • NH90 is a medium-lift, multi-role military helicopter resulting from an extensive European collaboration programme developed from NATO Staff Requirements;
  • SW-4 is a light, single-engine multi-mission helicopter, designed to operate in day and night for operational and training purposes;
  • AW609 TiltRotor is a hybrid aircraft combining the benefits of a helicopter and a fixed-wing aircraft, providing new levels of performance, safety, reliability and affordability. It takes off and lands vertically but flies above adverse weather conditions in a pressurised cabin at twice the speed and range of typical helicopters.
AW609 in forward flight and hover modes