GKN Aerospace's ASPIRE program targets next-gen composite wing manufacturing technologies

Somewhere in GKN Aerospace’s (Bristol, U.K.) Global Technology Centre, there is a composite technician hand-rolling carbon fiber prepreg into what are known as noodles. These are individual sections nearly a meter long, shaped into a slender, triangular cross-section to become a deltoid filler that occupies the three-way radius joint where a composite spar or rib mates with the skin it’s stiffening. The technique, for all its precision, is not meaningfully different from what it was 30 years ago.

“The manual aspects of fabricating the noodles and other composite aerospace parts carry a weight in production far beyond the obvious,” says Tony Lloyd, GKN Aerospace principal composite research engineer and ASPIRE technical lead. “A next-generation single-aisle [NGSA] aircraft will require between 1,000 and 2,000 meters of these noodles per airframe. If Airbus reaches its stated production ambition of between 60 and 100 single-aisle aircraft per month, hand-rolling becomes a genuine bottleneck as a single anachronism that holds back an otherwise advancing manufacturing system.”

The noodle, in other words, is a symptom. The underlying condition is the composite aerospace industry’s persistent dependency on manufacturing approaches conceived in a different production era — where fiber layups are locked into the classic 0°/±45°/90° quasi-isotropic conventions, autoclave pressure vessels are required for curing and manual preforming is necessary for geometries that automated deposition cannot easily reach. These defaults have produced extraordinary structures. They have also reached the practical limit of what they can offer in terms of production rate, structural weight and embodied carbon for the next generation of narrowbody aircraft.

This is the problem ASPIRE (Advanced Structural with Product Integrated AiRframE) was established to address. Launched in May 2025 and running through April 2028, the £12 million program is led by GKN Aerospace and partly funded through the U.K.’s Aerospace Technology Institute (ATI, Bedfordshire), Innovate UK (Swindon) and Department for Business and Trade (London). Its five specialist partners — iCOMAT (Bristol, U.K.), Carbon ThreeSixty (Chippenham, U.K.), Lineat Composites (Chepstow, U.K.), Pentaxia (Derby, U.K.) and the University of Bath (Bath, U.K.) — each address a specific failure mode in the current composites manufacturing paradigm. What makes ASPIRE unusual is that all five technologies are being deployed simultaneously, against the same structural geometry, and tested under the same conditions so the cumulative effect can be measured rather than estimated.

Three variants, one test campaign

The structural backbone of ASPIRE is a set of three full-scale composite wingtip variants, all derived from the folding wingtip geometry that Airbus (Toulouse, France) expects to feature on its next single-aisle aircraft. This is a design that extends the total effective wingspan by approximately 10 meters while allowing the tip to fold for airport gate compatibility. Airbus has provided baseline load cases and geometric guidance while GKN Aerospace holds design authority for the ASPIRE project. All three variants will be structurally tested to ultimate load at GKN’s Isle of Wight test facilities, the standard aerospace certification threshold representing 1.5X the maximum in-service load, with results expected in late 2027 and early 2028.

Variant 1 is a bonded assembly using more traditional build and design methods currently seen in aerospace but with an optimized structural architecture specifically for bonding. The method for bonding draws on the outputs of MaBOND, a parallel U.K. program led by GKN, that is advancing automated bonding methods for primary structures. Bonded construction reduces fastener count and part complexity and, if it passes ultimate load testing in a primary structure context, meaningfully advances the regulatory acceptance of bonded joints in single-aisle aircraft.

Variant 2 represents the current state of the art. It is a quasi-isotropic co-infused resin transfer molding (RTM) structure built using automated preform deposition, digital twin integration and GKN Aerospace’s SmaRTM processing. This variant is believed to be the best available today using the automated RTM cell developed through the preceding ASCEND program (read CW’s “ASCEND program completion”). Pentaxia’s JouleTool self-heated mold is integrated at this stage, providing low-energy, self-heated tooling for automated 3D preforming of the wingtip skins.

Variant 3 is where the existing rulebook is set aside. Nonstandard fiber angles, enabled by iCOMAT’s rapid tow shearing (RTS) technology, replace the quasi-isotropic default in the skins and spars. Low-energy dry fiber forming feeds GKN’s SmaRTM process. Carbon ThreeSixty’s stitched deltoid noodles manufactured from recycled carbon fiber (rCF) aligned through Lineat’s aligned fiber forming technology (AFFT) process replaces the hand-rolled fillers. The University of Bath’s probabilistic analysis tools provide the structural design confidence that will be needed before any of this approaches a production aircraft.

Alongside the three wingtips, ASPIRE is developing an optimized wing movable in the form of a notional flap demonstrator. The flap advances fast-cure thermoset prepreg-manufactured structures with RTS-optimized skins, tailored fiber placed (TFP) brackets and low-energy, out-of-autoclave (OOA) curing molds, with a key program milestone being the achievement of TRL 6 for fast-cure thermoset press-cured composite ribs. This builds directly on GKN Aerospace’s experience producing A350 flaps at its Munich, Germany facility.

Stitching the noodle

Carbon ThreeSixty brings more than 6 years of dry fiber TFP preform manufacturing experience to the deltoid noodle challenge. In TFP, which is essentially computer-controlled fiber embroidery onto a backing layer, the machine deposits fiber tow along a user-defined path, stitch-fixing it to the substrate and building up a near-net-shape preform without the cutting waste of conventional ply-based methods. The process has been proven across a wide range of structural preform geometries. For the ASPIRE project, the deltoid noodle introduces a specific new constraint where three knife-edge vertices converge toward a near-zero radius, each of which must be filled completely and held dimensionally through the infusion cycle.

“In previous applications, we’ve been doing all sorts of different shapes but not trying to go down to that kind of knife edge,” notes Carbon ThreeSixty’s technical lead, Sarthak Mahapatra. “What’s different in ASPIRE is achieving a stable, precise fill of the deltoid corners in a format that stays dimensionally consistent right through to injection.” The company has filed a patent on the resulting manufacturing approach, which it views as foundational to broader TFP noodle applications across the aerospace supply chain.

The fiber for those noodles comes from Lineat, a University of Bristol spinout producing AFFT tape made from a short fiber material in which rCF has been re-aligned along a common axis using a proprietary fluid dynamics process. To understand what makes this difficult, consider the analogy of papermaking: paper mills disperse fibers into a random, isotropic slurry precisely to produce a uniform sheet. Lineat’s process does the opposite, driving alignment in a suspension of carbon fibers between 4 and 10 millimeters long and just 7 micrometers in diameter, producing a unidirectional (UD)-like tape from a discontinuous feedstock.

“The difference between a fiber being aligned and unaligned affects the whole specification and property of that material,” says Gary Owen, Lineat’s commercial director. “Understanding those fluid dynamics at a 7-micron scale, knowing how the shape of a droplet hitting a plate affects the flow, knowing how each variable interacts and validating the alignment of the material — that’s where the real complexity is.”

The resulting AFFT aligned fiber tape is stabilized with an acrylic binder, compatible with standard thermoset and thermoplastic matrix systems. Lineat’s pilot line can produce 1,000 meters of 100-millimeter-wide tape per day that scales substantially when the tape is reformatted to noodle-feed width.

Critically, the AFFT tape retains approximately 80% of the stiffness of virgin UD carbon fiber, and for the noodle application, that figure is specification. A noodle should not transfer primary loads between structural elements; its function is void filling and local compressive stiffness at the radius joint. A continuous fiber running the full noodle length would intercept structural loads in the joint unpredictably, complicating the design of the spar geometry around it. Lineat’s short, aligned fiber architecture prevents that load path by design while still providing the stiffness needed to resist void collapse under infusion pressure.

The same AFFT tape may carry a second function in ASPIRE. Pentaxia is currently investigating whether Lineat’s recycled discontinuous fiber could serve as the heating element within its self-heated JouleTool molds. Carbon fiber is conductive, which makes it an attractive candidate for joule heating, but standard UD carbon fiber has low electrical resistance, demanding high currents at tool scale to generate sufficient heat. The short fiber breaks inherent in Lineat’s aligned discontinuous tape introduce resistance discontinuities throughout, increasing total resistance and reducing the current requirement. It is an unplanned synthesis between two partner technologies, and one that could simplify the company’s JouleTool’s electrical architecture considerably.

Steering the design

ICOMAT’s RTS technology (read CW’s “Industrializing rapid tape shearing for high-rate, 3D composite structures”) places fiber tows at nonstandard angles by shearing the tow width rather than bending the tow path. This eliminates the gaps and overlaps that conventional automated fiber placement (AFP) introduces above approximately ±30° from the primary deposition axis, and delivers a continuous, defect-free fiber architecture at orientations that AFP cannot achieve. The result is a vastly expanded design space, so rather than selecting from the three standard angle families, a designer working with RTS can specify any in-plane fiber direction at any point on the laminate surface.

For the ASPIRE wingtip skins and spars, this creates two simultaneous opportunities. Structurally, fibers can be continuously routed around access panel cutouts and geometric discontinuities, maintaining uninterrupted load paths where quasi-isotropic laminates would rely on local reinforcement overlays. In terms of manufacturability, pre-optimized fiber steering can counteract the wrinkling modes that develop when a flat laminate is drawn over a complex tool surface during forming, reducing defect initiation without adding post-cure rework. For the flap, iCOMAT’s team is addressing a more demanding geometry, where GKN Aerospace’s engineers self-identified a waffle-pattern internal structure which has a corrugated topology with frequent tight-radius folds as a forming challenge that conventional AFP could not resolve. RTS is being applied to define the fiber paths that enable that structure to be formed cleanly from a flat preform.

“There’s no easy way of designing variable-angle laminates using classic engineering rules,” explains Olivia Stodieck, iCOMAT’s director of composites engineering. “You need optimization algorithms that can handle the complexity, and then you need to communicate the design intent in a form your manufacturing partner can integrate directly into their tools.” A dedicated ASPIRE work package is building that integration layer linking iCOMAT’s RTS design and simulation environment with GKN Aerospace’s structural analysis tools so that fiber angle optimization and structural verification happen in a shared digital space, rather than sequentially across an interface.

The University of Bath provides the analytical foundation to give confidence in the nonstandard angle composite designs. Professors Richard Butler and David Williams lead Bath’s contribution, drawing on a 15-year structural research partnership with GKN Aerospace that has involved more than 20 Ph.D.s, an EPSRC program grant (CERTEST) on composite certification and now an EPSRC prosperity partnership (ZENITH). Bath is developing analytical and numerical methods to take advantage of the design freedom given by nonstandard fiber angle composite laminates. These methods, in areas such as formability, damage tolerance, aeroelasticity and noodle performance, will provide input to the design process of wingtip Variant 3. The aim is to gain a deeper understanding of how these nonstandard angle laminates can be used most effectively to reduce weight while retaining performance and manufacturability. There is also a need to provide a route to increased use of analysis-based certification for these laminates.

“Because you’re freeing up the design space, it will be impossible to test all permutations,” says Butler. “The challenge is creating confidence in the analysis method so that it can become a tool for certification and something regulators can accept as a valid basis for approval without requiring a test campaign that could never be completed.”

The University of Bath has already engaged both the Federal Aviation Administration (FAA) and European Union Aviation Safety Agency (EASA) in early discussions about analysis-led certification pathways for nonstandard angle composites. ASPIRE Variant 3’s structural test results will be the first primary structure validation data those conversations can draw on.

Cutting the energy bill

Autoclave curing is the energy-dominant step in composite wing manufacture, and for components at wing-structure scale, it is also the scheduling bottleneck. Pentaxia’s JouleTool addresses both by embedding resistive heating elements directly within the composite mold tool, allowing it to generate and apply cure heat from a standard electrical supply without the pressure vessel. The tool heats the part from the tool face outward rather than from the ambient atmosphere inward as it’s the most efficient direction thermally.

Pentaxia has been developing JouleTool through approximately 5 years of internal and commercial programs, and has demonstrated 80-90% energy savings compared to autoclave processing for large composite components. ASPIRE is the program that will take the technology to TRL 6 in an aerospace-scale, aerospace-quality manufacturing context. The primary deliverable is a lower wingtip skin preforming tool approximately 4 meters long × 1.5-2 meters wide, instrumented for RTM binder activation at 120°C, with a stretch objective of achieving 180°C cure for the advanced prepreg materials being used in the flap skins — around the thermal threshold for full prepreg consolidation and the most demanding condition the technology will face in a composite application.

“Our aim is that someone can give us their surface geometry and we can make a JouleTool package that suits their cure schedule and their component requirements,” says James Smith, business manager at Pentaxia. “The control unit has to be as familiar as an autoclave controller and enable automated cure input, scheduling and running.” The ASPIRE program control unit produces a digital twin output compatible with GKN Aerospace’s automated cell, making the JouleTool a native node in the digital manufacturing environment and enabling the real-time process monitoring that aerospace quality systems demand.

The heating element design itself remains in active development. Copper veil, which is the conventional material approach for internal heating, is effective but adds an extraneous material system within the composite tooling stack. UD carbon fiber as a heating element offers material consistency but generates low resistance, demanding high currents at tooling scale. The Lineat AFFT tape route would introduce a material that is already qualified within the program, provides tuneable resistance through fiber length and alignment density, and carries a sustainability benefit through its recycled feedstock. The ASPIRE program will determine which route offers the most robust engineering solution.

Demonstration to test 

The value of testing all three wingtip variants to ultimate load, rather than to a sub-scale coupon program or finite element predictions alone, is that the aerospace industry only has one currency for certification: physical evidence at relevant scale. All three variants are built to the same Airbus-derived geometry and tested under the same load cases. The weight differential between variants will be measured directly. More significantly, if the University of Bath’s probabilistic analysis tools correctly predict the structural behavior of Variant 3, ASPIRE will have demonstrated a route to certify nonstandard angle composite structures that the current regulatory framework does not yet accommodate.

ASPIRE follows the ASCEND program, which concluded in March 2025 and established the manufacturing infrastructure of automated RTM cells, high-rate prepreg systems, digital twins and sustainability frameworks on which several ASPIRE technologies are directly built. Where ASCEND asked how to produce composite structures faster and more consistently, ASPIRE asks what a genuinely reconceived structure looks like when those production capabilities are already in place. The two programs are sequential arguments in the same case: that the U.K. composites industry has the knowledge, the supply chain and the physical evidence to lead the next generation of commercial aircraft structures.  

“We’re not just trying to make things a bit lighter or a bit cheaper,” says GKN’s Lloyd. “We want to show that if you think differently about composites, if you use different design rules, recycled materials and better tooling, and then you test it the same way you’d test anything going on an aircraft, then you can achieve genuine benefit. Numbers on paper don’t move the aerospace industry. Test data does.”

By April 2028, ASPIRE will have produced the three ultimate load tested wingtip structures and an advanced movable wing, all built using technologies that today’s design and certification standards do not fully describe. That gap between what the tests will have shown and what the rulebooks currently allow is precisely what this program is designed to bridge.