Greater than the sum of its parts

Mike Richardson


discovers why Bombardier Aerospace Belfast's efforts to reduce the total number of CSeries wing components and simplify the assembly process of its composite wing development programme will be good news for its airline customers' operating efficiency and environmental footprint.

With almost 40 years' experience in the composites arena, Bombardier Aerospace Belfast is playing a major role in a number of national and European R&D programmes, including the Next Generation Composite Wing (NGCW) programme aimed at producing cleaner, more efficient and environmentally friendly aircraft of the future.

The Belfast facility is now also responsible for the design, development, certification and manufacture of the CSeries carbon composite outer wing, including the control surfaces, as well as the integration of the wing systems. The primary structural components, which are the integrally stiffened upper and lower skin panels and the spars, will be manufactured using Bombardier's Resin Transfer Infusion (RTI) process – a truly innovative and major step forward in the evolution of advanced composites technology developed in its R&D labs in Belfast, and which includes the construction and testing of a full-scale, three-quarter span demonstrator wing.

RTI is a hybrid of Resin Transfer Moulding (RTM) and autoclave processing and is a patented process developed solely by the Belfast operation. It involves the use of dry fabrics to create the structure and then injecting resin into the structure once it is placed in the autoclave. This results in material savings and reduced cycle times.

Winged wonders

Typically, the construction of a traditional metallic wing panel will comprise several panels joined by conventional fasteners, whilst the wing skins themselves are often complex subassemblies made of many panels with the stringers and stiffeners attached to the wing skin panels separately. Compare this to the CSeries' advanced carbon fibre wing panels, which consist of large panels fabricated as a single piece with the stringers and stiffeners integrated within the wing skin and you can see why there is a great deal of interest and activity surrounding the wing development programme.

“The use of advanced carbon fibre composites for the construction of the wing is fundamental to what we are doing at Belfast; particularly with the resin transfer infusion technology,” explains Bombardier Aerospace, Belfast's director of design engineering and technology development, Gavin Campbell. “This is an innovative technology and delivers a number of benefits; one of which is that it helps reduce airframe weight to make a direct contribution to both fuel burn and operating efficiency. It also helps reduce the environmental impact of the aircraft, because the less fuel you burn, the less CO

₂

and NO

_X

emissions there will be as a result. These are the factors that have influenced the choice of the CSeries' material system. Other benefits to the customer include reduced inspection and maintenance activities due to the corrosion-free properties of the materials.”

Good news all round

Bombardier Aerospace, Belfast currently has two dedicated composite manufacturing facilities in Dunmurry and Newtownabbey. Associated plant includes six inert gas autoclaves, automatic tape layer, computerised nesting and automated cutting, automated honeycomb reticulation and robotic adhesive spraying, laser projection, 5-axis CNC trimming with integrated flexible tooling, waterjet trimming, and advanced shopfloor management systems to ensure optimum use of materials manpower and autoclave utilisation.

Meanwhile, construction is under way on the new composite manufacturing facility required to produce the CSeries wings. As part of the £520 million investment in the CSeries programme in Belfast, the new factory will feature state-of-the-art infrastructure and will house all of the highly specialised, manufacturing equipment for the RTI advanced composites process.

The CSeries investment is the largest ever single inward investment in Northern Ireland, and will sustain more than 800 jobs at peak production. In addition, it will benefit many suppliers, subcontractors and other service firms.

“The spin-off benefits in regions of the UK, throughout Europe and worldwide are significant,” continues Campbell. “Bombardier Belfast currently has around 900 approved suppliers throughout the UK and Ireland, and some of these will be engaged on the CSeries programme either directly through Bombardier, or via some of our supply chain partners.”

As with the rest of the CSeries programme, Campbell confirms that the wing development programme is progressing on schedule and will meet all its expectations. Bombardier continues to build on its experience of composites technology and is currently making bold strides towards testing and proving out the design, as well as the manufacturing and assembly processes relating to the RTI technique. This requires producing a pre-production wing demonstrator on which it will replicate every possible combination of the most severe loading that the wing will ever experience in service.

“So far, we're delighted with the quality of all the RTI wing components we've made to date for the demonstrator programme, and are confident that the RTI process is an excellent method of manufacturing very large and complex one-piece composite structures,” he says. “Many of our Belfast engineers see this as the realisation of the next logical step in the path of technological development, and there has been a real and personal engagement with the programme and the technical demands it requires. There is certainly a great buzz of excitement around this programme.”

The design and production of the advanced composite wings will significantly progress Belfast's capabilities and skills, enabling the company to move up the value chain and compete successfully in the future international marketplace, as well as adding to the UK's strategic interests in this area.

Looking to the future, Bombardier wants to advance the application of new joining methods that will help reduce an aircraft's bill of materials and simplify the manufacture and assembly process. It is also investigating more weight reductions and performance improvements to provide further end of service benefits.

“Our ongoing R&D strategy starts by looking at the high level objectives - whether they are the environmental step changes the entire industry is searching for at the moment or the lifecycle cost benefits that will flow directly through to our customers,” he concludes. “Bombardier is already moving beyond CSeries to look at further developments in these and other technologies that will be applied to future generations of aircraft designs.”

www.bombardier.com