MICHAEL PHELAN / PARIS
Computer-aided design of aircraft is taking on a new dimension with Dassault's 7X business jet with supplies connected through a "virtual plateau"
Computer-aided design software has been around for more than two decades and pervades nearly every aspect of modern aircraft development. With packages such as Dassault Systèmes' Catia accepted by engineers and integrated into design processes, one could argue that the main benefits of such systems have been realised - a less paper-based work environment and the ability to view rapidly the effects of local changes across the entire design.
But developers of new suites of design-management software believe there is scope for far more wide-reaching process-management software in aircraft design and manufacturing.
Dassault Systèmes is among the developers leading the charge and some of its products' more innovative features are being used by its sister company Dassault Aviation in designing its trijet Falcon 7X business jet. The 10,550km (5,700nm)-range 7X is set to become Dassault's flagship when it enters service in 2006. It features the same cabin cross-section as the venerable Falcon 900 family, but with a 2.45m (8ft) fuselage stretch, a new wing for M0.9 maximum operating speed, fly-by-wire controls and a new "intuitive" cockpit featuring large 360mm graphical displays.
When preliminary design of Dassault's latest business jet began in September 2001, the company set up a design "plateau" at its Saint-Cloud, France, design office. In its first phase, which lasted until September last year, the plateau consisted of about 380 technical and engineering staff co-located in one large office contributing to a single virtual 3D design model, complete with systems, wiring and structure.
Bernard Dimoyat, Dassault Aviation engineering vice-president of the Falcon 7X joint design team, explains that only about 40% of the personnel were Dassault employees. "We had representatives from more than 20 risk-sharing partner suppliers included in the team," he says.
For the detailed design phase, which began last September, Dassault is managing a "virtual plateau" design office. Essentially the same in function as the preliminary design plateau, during this phase the suppliers have moved back to their home bases and submit and receive design updates over a secure shared computer link. "Once we entered the current design phase, we just had too many people to fit in our original plateau," says Dimoyat, "but there's very little difference in the way we work now."
Dimoyat believes the set-up is superior to previous Catia-only digital models because of the amount of information the users can access. "This is the first time that we can exchange the full context of the design, the full bill of materials [BOM]," he says. "Each seat has a Catia workstation and a PC so users can access the written documents as well as the design models." Users working on various components or systems have tailored access permissions that allow them to see all information relevant to their work, including that generated by other suppliers for neighbouring components or interfaces. "All files are updated twice each week and put into the system for all to see," he adds.
Dassault is using Enovia-VPM (virtual product modelling) for technical data management and Delmia for production, maintenance planning and life-cycle management. The three software packages form part of the 3D PLM (product life management) product, which is marketed by Dassault Systèmes and IBM. Delmia aims to anticipate product behaviour and manufacturing operations. By modelling the future behaviour of products, the risk of product failure, production inefficiency or market mismatches are reduced, says Dassault. The management of the most up-to-date data configuration is handled by Documentum, a content management tool.
Production views have been added to the 7X digital modelling capability last year, and the product support views are now being added. "With several contextual views of the same parts available from a single master BOM, we know we are all working from the one standard BOM at any given time," says Dimoyat.
The ultimate success of the virtual plateau depends on the subscription of Dassault's risk-sharing suppliers and their trust in placing proprietary data at its mercy. Dassault Systèmes is selling the virtual plateau-enabling hardware and software to the 7X partners who wish to participate.
Virtual sale
Dimoyat says that, following a pilot deployment of the virtual plateau with French structural supplier Latécoère last year, the first package was bought from Dassault Systèmes at year-end. "We have about 10 partners fully subscribed to their local areas and interfaces, out of about 21 involved in the programme," he says. "Those 10 account for most of the design, and each month we're adding more [subscribed partners]," he adds.
The main virtual plateau models are held on computer servers at Saint-Cloud, but each partner receives smaller versions of the data relevant to themselves, for hosting local systems on their own "virtual plateau package", if required. This is especially useful if jobs are being performed on large models, when it is better to make the changes to "local" versions and then upload the completed job to Saint-Cloud at a later date. A virtual private network with a data transfer speed of between 512Kb/s and 2Mb/s connects all the partners.
Another innovative feature of Dassault's design set-up is the 3D virtual reality centre (VRC) at Saint-Cloud, which allows engineers to view lifesize models of the aircraft. Viewers wear special light-polarising glasses to achieve the illusion of a 3D image, and can view the model from any perspective at any scale. Colour-coding allows easy recognition of different systems, and the tool can be used to determine equipment accessibility and troubleshoot spatial interference.
Dimoyat is enthusiastic about the way the virtual plateau philosophy has functioned, and is sure it will be the preferred design method for future programmes.
"While it's difficult to compare this programme to our last 'from scratch' design [the Falcon 2000 in the early 1990s], certainly we have shortened the time for preliminary and detail design," he says. "For me, the major difference is we're gaining maximum benefit from the way data is exchanged and managed." Dimoyat emphasises the importance of the word "exchange" to highlight a difference compared to past practices. "The partners deliver information to Dassault twice each week, but we also send out all of our updated data with the same frequency," he says.
The 7X detail design phase is coming to a close for some components, with manufacturing launched on some long lead-time items. High-speed windtunnel testing is ongoing, with low-speed tunnel testing in the coming weeks. First flight is set for 2005, with service entry the following year.
Source: Flight International
