Dassault has taken the next step in digital design and manufacturing with its Catia software and Falcon 7X business jet
Visitors to Dassault Aviation's Falcon 7X development centre at its Paris headquarters are treated to an experience they may associate more with childhood than with the creation of a new business jet.
In the new Virtual Reality Centre (VRC) they are handed a pair of specially developed spectacles with which to view the Falcon 7X design in all its aspects. The result is dramatic, as the images spring from the 6m (19.7ft)-wide screen in the 30-seat VRC and become three-dimensional. The effect creates a natural urge to duck as the digitally created image is rotated and appears to penetrate the viewing area.
The VRC is but one component in a new design process that Dassault has introduced for the Falcon 7X, which it claims will reduce assembly time for the business jet by 30%. "This aircraft is not just new. It's 100% new," says senior vice-president, civil aircraft, Olivier Villa. The Falcon 7X design process is the result of an "industrial revolution", he says.
Development of the all-new Falcon 7X is taking advantage of years of experience with the Catia computer-aided design software, developed in-house by Dassault and now the industry benchmark for three-dimensional product definition.
Catia allowed engineers for the first time to navigate through the intricacies of a design displayed digitally on a computer screen. Product visualisation was improved at a stroke, while time previously spent producing new drawings whenever a design change was introduced was drastically reduced. New ideas could be tried out before major configuration decisions were made.
Now the sister company that created Catia, Dassault Systemes, has taken the obvious next step by linking the design and manufacturing processes, so that for the first time the digital model of the aircraft contains sufficient information for it to be used also for production. Information contained in Catia, and its associated Delmia and Enovia product data management software packages, provides all of the detail necessary for manufacture. "Essentially, we have eliminated the production engineering phase," says Villa.
For the Falcon 7X, Dassault has created a digital mock-up of the aircraft, eliminating the time-consuming and expensive creation of a physical version. In the VRC, engineers can thread their way through the design, viewing components, wiring, tubing and even rivets and electrical connectors, down to the finest detail.
The database contains a 100% definition of every part, which means the relationship between them can be ascertained long before they are assembled into the whole machine. "It means we can be absolutely certain, for example, that all of the holes will fit when we assemble panels to brackets and fittings," says Falcon 7X programme director Vincent Oldrati. "So we can validate the entire manufacturing process very early on. We can design tooling, and we can work out maintenance aspects at the beginning rather than at the end of the design."
In a further move that has totally changed its relationships with suppliers, Dassault has created a "virtual plateau" at its St Cloud, Paris headquarters, linking all of the major subcontractors with the Falcon 7X digital database. For the preliminary design phase, all were physically present at St Cloud. "At its peak, the physical plateau bought together 400 people from 27 companies and seven countries. Then they went home to work together on our unique, shared database," says Oldrati.
Suppliers are connected in real time via a France Telecom-supplied permanent datalink, and design issues are settled in "virtual meetings" centred at St Cloud. "It's the first time this has ever been done," says Villa. "There's no comparison with the past, when often incomplete data was released early, to save time. This had to be updated later. Now, all changes are in real time."
The network includes not only Dassault's own factories, but those of foreign suppliers such as Pratt & Whitney Canada, which is developing the PW307A turbofan to power the trijet Falcon 7X.
Definition of the Falcon 7X was achieved a record 16 months before the first flight, planned for the second quarter of 2005. The resulting database contains more than 100,000 3D models including brackets, ducting, wires and equipment as well as more than 300,000 fasteners.
The digital design process used a "virtual lofting" technique to create the 3D layout of the Falcon 7X. "We produce a first iteration taking the 3D aerodynamic analysis of the aircraft into account," says J‚r"me Camps, design office engineer. "Then we derive a simple finite-element model to check the overall design. Next, we cut virtual sections through the fuselage to give an idea of load flowpaths." In parallel, a preliminary systems layout is prepared. "Then it's all coupled together. We understand the balance of the aircraft from a very early stage. We have to be able to ensure that key junctions are properly sized and dimensioned. So every structural element is designed in parallel with systems, tubing, wiring, fuel and so on." The result is that the first few weeks of the design process resolves difficult issues such as equipment space allocation, which can too often be left until later, when changes - if they are possible at that stage - cost more time and money.
The new design system was first used on the Dassault Rafale multirole fighter and on the Falcon 2000 business jet. "But on the Falcon 7X we've pushed it much further," says Camps. "Now we do comprehensive design, manufacture, ergonomics and maintenance, all from the same database. When you have a well-organised database you can use it for everything. It becomes the central tool for all departments. Anyone in the company can select anything and check it against a product tree, using a user-friendly navigation system."
The central database is also used to create the tooling for parts manufacture and for generating assembly jigs, and creates 3D digital mannequins to check the ease with which pilots can use the cockpit and mechanics can access service areas.
Access to the system has to be controlled, to prevent "unlawful" updates. "Policing is done with a control management system," says Edouard Datin, programme engineer. "We never change anything unless it is written down on paper and passed to a commission. In the virtual plateau phase we control everything, even the bolts. This is the first time we've had really accurate control management at the beginning of the programme, from the first click on a mouse. Everyone is aware of what is happening."
A dedicated team supervises the complete design, checks compatibility and validates any changes that are made. "We spend many, many hours looking for clashes. There are a lot of examples of not seeing clashes in two dimensions that we have seen in three dimensions," says Camps. "If there's a clash a report is issued so that all are aware of it. It's usually resolved within 48 hours. That's a huge advance."
Robert de Rocquigny, vice-president operations in charge of Falcon production, says: "We're launching the Falcon 7X as a full production aircraft from day one. We intend to have more than 15 basic aircraft ready by certification and for deliveries to begin immediately after. The Falcon 7X is a major step forward in completion time. We have to be smart enough to do it quicker. At present, completion takes between three and five months. I want it to be less than three, both for economy and flexibility."
Dassault's completion centre at Little Rock, Arkansas has full access to the digital mock-up, greatly easing the task of customising the interior to suit individual needs, some of which are "quite specific", says de Rocquigny. "We share the model of the interior and cockpit to speed the customisation process," he adds. "Then we know the parts will be manufactured correctly, because they're part of the database." This includes "wet" parts such as the toilet and galley plumbing, which, because of Little Rock's access to the central database, can be designed from the outset for mounting in locations not used by anything else. "We take their requirements in from day one and give them the attachment points. They get everything they need to design and produce their interior because it is all specified and prepared. At present it has to be adjusted for every aircraft, which can be a nightmare," says de Rocquigny.
Delivery of the first Falcon 7X fuselage to Merignac for final assembly is due by 14 July, completing the company's fastest-ever design-to-production cycle for an airframe. "It is possible because everything fits perfectly from day one," says de Rocquigny. "Before it took between 10 and 30 airframes to get it right. This meant that documentation was different for every aircraft. Now they're identical. The holes drilled at our Seclin [Lille] factory fit perfectly with those drilled at Merignac. There is no more adjustment or trimming of parts. No-one has ever done this before."
The need for massive jigs to hold major components in position during assembly has virtually disappeared because they fit together so accurately. De Rocquigny compares it with assembling a Meccano model. The panels that make up the wing box, for example, have pre-drilled holes that match up perfectly during assembly, eliminating the need for a rigid mounting jig. "It took months before. Now it takes less than a month," he adds. Assembly of the lower fuselage from detailed parts began on 1 February and was complete by the end of April - half as long as before. The same applied to the wing, which will be delivered in mid-September for attachment to the fuselage. "We were very relieved it went so well. All we had to do was to check the results," says de Rocquigny.
The tools used to manufacture the airframe have also advanced, further improving productivity. For the wing, the main billets for the upper and lower panels are machined vertically, which makes them easier to work and quicker to mount and dismount. "The time it takes has been cut by a factor of three," says Christian Slagmulder, industrial programme manager at Seclin.
JULIAN MOXON / PARIS
Source: Flight International