Context The requirement of a lower environmental impact during the aircraft lifetime coupled with a growing demand for passenger safety motivates extensive research into the design of new aircraft models As part of the E‐Fan project, the first 100% electric and all composite aircraft, the partners RESCOLL and Institut Pprime ISAE‐ENSMA designed and followed the realization of the wing. This composite wing, of so‐called classical Colomban architecture, has been validated by the General Directorate of Civil Aviation (DGAC) and has demonstrated that it was possible to create an electric tourism airplane, first step towards future big carriers using this technology.
NEOFAC PROJECT : Pika & Rescoll partnership for industrialization, manufacturing and certification of
removable composite sandwich wing for tourism aircraft
The NEOFAC Project As an extension of the E‐Fan project, SRC Rescoll (Bordeaux ‐ Rochefort) and Institut Pprime (ISAE‐ENSMA ‐ Poitiers) decided in 2015 to continue their research on the development of innovative aeronautical structures. This 100% stakeholder partnership in New Aquitaine is the source of the NEOFAC project, partially financed by European regional development funds (ERDF) for 50% of a global budget close to 500 K€. A collaboration joined in 2017 by the company Pika to ensure the industrialization and manufacture of the prototype and the validation part. "The NEOFAC project consisted in designing, manufacturing and testing a full‐scale prototype of a composite box wing made of composite materials for a passenger aircraft (FAR 23 aeronautical regulations). RESCOLL and ISAE ENSMA have carried out predictive simulations that permits to size the structure and realize an optimization going beyond the initial requirements for passenger aircraft and allowing to support the 12g imposed to obtain a DGAC certification in aerobatics. Mechanical tests on semi‐structures have been used to make digital models more reliable, to make them predictive and to achieve reliable virtual optimization, "explains Anne‐Sophie Andreani, project manager at Rescoll in Rochefort. The composite box wing is a well‐known structure since the 90s, but it was mainly used in fighter jets with very high technology manufacturing processes. "A removable wing with a caisson architecture is less common and we had to adapt to standard manufacturing methods to transfer this architecture to passenger aircraft," says Anne‐Sophie Andreani. The Bayonne company PIKA took up this challenge within the framework of the NEOFAC program by producing a demonstrator for the Paris Air Show and the test piece in a leadtime of 5 months. The composite box wing consists of a monobloc part composed by an hollow box with integrated spars on the entire span. This new architecture was made in one‐shot autoclave process. The advantage is to reduce the number of manufacturing steps, the number of tools, consumables, and therefore the manufacturing costs. The box wing has to support all external loads exerted on it. Compared to a wing having classical architecture, the loads are not mainly carried by the spars but are taken by the sandwich skins and the spars. By reducing the number of parts (ribs, spar), the bonding areas are reduced, which optimizes the mechanical performance of the wing. The variable thickness of the sandwich skins also provides better buckling strength without weight gain. Finally, the box wing has an additional rigidity (23%) in flexion without torsion phenomenon at the end of the wing and a loss of mass of 10% compared to the composite wing of conventional architecture.
The sizing and optimization calculations carried out by Rescoll and Pprime resulted in a complex multi‐material mapping that Pika had to sample and put in data to initiate the phase of industrialization. Composites stacking areas
Once this sampling was done, the 3D CAD of the wing could be made as a basis for the study and realization of the various tools: preforming, molding / baking, surfacing / trimming of the honeycomb.
In parallel, the prepregs cutting files and the Ply Books were made in order to ensure a precision level of +/‐ 1 mm in the positioning of the different layers and thus to best fit the definition of the calculated part.
A 2 meters length prototype wing was realized in order to validate the feasibility of the built‐in one‐shot and autoclave sandwich box process. The second objective of this demonstrator was to present the concept and the progress of the NEOFAC project at the Paris Air Show 2017 on the Rescoll stand.
"This first achievement allowed us to validate our industrial studies and to confirm the box wing process that was ambitious step with limited resources and short lead times," said Olivier Proust, Product Development Engineer at Pika.
Intrados Ply Book Leading Edge Spar Ply Book
‘’Le Bourget’’ Prototype NEOFAC Wing at Paris Air Show 2017
With the feedback from the Le Bourget wing, Pika has lauched the manufacture of the validation part using almost all the means available in its factory and by manufacturing some key tools itself in order to ensure 100% internalized manufacturing from material supply to CN fabric cutting, draping with laser assistance, autoclave cooking and 5‐axis machining.
Spars Lay up and Compaction Nomex HC degressive machining
In early November 2017, RESCOLL tested removable box wing at scale 1 in its static test lab according to the DGAC requirements. The test program has validated that the box wing is able to withstand the 12g (breaking it occurred at 13g), that is to say, 40% more than the wing designed as part of the project E ‐Fan. These full‐scale evaluations confirm the results obtained in advance by the predictive design carried out by RESCOLL and the Pprime Institut. "This technical success encourages us to continue our work of development and validation of innovative aeronautical structures" says Anne‐Sophie Andreani. "We are convinced that this technical success could lead to an industrial success as the feedback of product / process experience is promising. The areas of improvement and automation are numerous with the contribution of current technologies making a series version of the wing box quite credible industrially and commercially "announces Patrick Orhategaray (CEO of Pika). The NEOFAC II project, in preparation, will involve the creation of a full‐scale demonstrator, including the fuselage.
The NEOFAC Project : From predictive simulation to certification test
Specialist in cutting '' all materials '' for 15 years, Pika recently settled on Bayonne's Technocité in a new factory dedicated to its original business and integrating a new unit: Pika Composite which is positioned on the study and realization of composite semi-products (cuts, kits, mattresses, preforms) as well as high-performance finished parts for aeronautics, boating and industry. The company equipped with modern means to cut (with water jet, laser, vibrating knife and CNC milling) all types of soft and metallic materials in the Pika Tôlerie unit. As for the Composites workshop, it has state-of-the-art industrial facilities for the production of composite parts using RTM, infusion and pre-impregnated oven processes. In 2016, a 10 bar autoclave - 400 ° C and a large 5-axis machining machine were added to the list of industrial tools to go even further in the manufacture of complex parts made of composite materials. Contacts : Patrick Orhategaray, Gérôme Sonois Site : www.pika-sa.com
In the field of industrial applications of polymer materials: composites, resins, adhesives, coatings, ... Having its own means of analysis and characterization of the material to the structure, RESCOLL is able to conduct applied research and technological development studies in their entirety, ranging from the definition and characterization of materials, the development of point of the processes of implementation, until the qualification of the behavior of the samplings, parts and structures as well as the study of the long-term behavior (aging, fatigue, creep ...). RESCOLL puts at the service of SME / SMI and large industrial groups its expertise to define, qualify, validate or appraise their products, ensuring responsiveness and confidentiality. RESCOLL employs a hundred people at its two sites in Pessac (33) and Rochefort (17). Contacts : Anne-Sophie Andreani, Nicolas Vétel Site : www.rescoll.fr
The PPRIME Institute - UPR CNRS3346, is a UPR CNRS created in 2010 in partnership with ISAE-ENSMA and the University of Poitiers; it brings together 600 people. Its nationally and internationally recognized activities cover physics and materials mechanics, fluid and material mechanics, mechanical engineering and energetics. Within the Physics and Mechanics of Materials Department, research focuses specifically on the relationship between microstructure and defects present in the heart of materials with their physical and mechanical properties.
Scientific approaches are experimental as well as theoretical and numerical, they integrate multi-scale and multiphysics issues. In the fields of aeronautical transport, the general objectives are to control the service life of materials and structures used in extreme situations and the optimization of their microstructures.
Contacts : Jean-Claude Grandidier, Eric Lainé Site : www.pprime.fr
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