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Light weight airframe structures through combination with high performance materials

Periodic Reporting for period 2 - LightAir (Light weight airframe structures through combination with high performance materials)

Período documentado: 2019-11-01 hasta 2020-11-30

The new rotorcraft architecture developed by the Topic Manager and which will be demonstrated under FRC IADP aims at demonstrating that the compound rotorcraft configuration implementing and combining cutting-edge technologies as from the current Clean Sky Programme opens up new mobility roles that neither conventional helicopters nor fixed wing aircraft can currently cover in a way sustainable for both the operators and the industry.

The project will ultimately substantiate the possibility to combine in an advanced rotorcraft the high cruise speed, low fuel consumption and gas emission, low community noise impact, and productivity for operators. A large scale flightworthy demonstrator embodying the new European compound rotorcraft architecture will be designed, integrated and flight tested.

Innovation target is to achieve a weight reduction of about 15% for general airframe parts (monolithic and sandwich) and particularly shell structures like side shells, tailboom, horizontal and vertical stabilizer and the wings. Some of these shell structures, like the tailboom and wings have
mainly stiffness driven designs, were materials with higher stiffness increase directly the performance. By a combination of the standard structural materials with new high performance materials in the relevant areas, a weight saving potential is obvious.

The general objective of the LightAir project is to perform a complete characterization of three new materials proposed in the call (adhesive, composite and honeycomb) as well as to account for the scatter of material properties using statistical analysis to obtain design allowables.
To achieve the main objective several partial sub-objectives were defined. These sub-objectives are listed below along with a brief description of the work done during the reporting period towards its achievement.
• Manufacturing of coupons, elements and details according to aeronautical standards.
• Determination of design allowables from mechanical and physical characterization tests of coupons and elements.
• Implementation of new experimental techniques, at industrial scale, to obtain translaminar fracture properties of the composite, and complete constitutive traction separation laws (cohesive laws) under different environmental conditions
• Analysis of sub-structural details and implementation of new instrumentation techniques to reduce the number of specimens
• Statistical analysis of design allowables, and implementation of Bootstrapping to reduce the number of samples.
A Qualification Test Plan to characterize the new materials has been defined and discussed. It covers 3 levels of testing of the building block approach, from coupons to structural details.

The design and manufacturing of specimens for the 3 levels of testing (coupons, details and elements) is fulfilled. The design and manufacturing of the test rigs to perform the different testing campaigns is also finished.

The qualification test campaign is finished fulfilling the initial objectives. Apart from carrying the widespread characterization tests, the testing campaign includes the generation of new test procedures based on test standards and new test methodologies, the preparation of data reduction methods and calculations, and the validation and approval of these data reduction methodologies and the design and manufacturing of specific test fixtures and rigs. The aforementioned activities have been discussed and revised by the Topic Manager (TM), and fully completed.

A full material card data of the new materials (CFRP laminate, adhesive and honeycomb) together with a complete card of the design allowables have been provided to the Topic Manager. A discussion of the result is also provided to help to the TM in the decision of the implementation of the new materials into the new rotorcraft prototype.

All the manufacturing and test data has been collected into the TM server. A data management plan, which links the information provided by each partner has been created and stored into the TM server.

The partial and final results of the project have been disseminated and communicated through different platforms: a project webpage, news and press release by each of the project partners, CORDIS platform, etc. Internally, a project logo, document and presentation templates have been created. To overcome the pandemic restrictions that have affected the attendance to industrial and research conferences, the consortium is currently preparing scientific publications to be submitted to external peer-review journals. It is expected to submit them within one year after the end of the project.
A comprehensive understanding of the mechanical behaviour of the new materials evaluated has been reached.

LightAir project has designed and performed a material qualification campaign and performance assessment that will contribute to (i) have a better understanding of three mainly used materials in an airframe structure and to (ii) improve design allowables with respect to existing materials. A direct impact from these two contributions is a significant drop in the weight of the rotorcraft structure. The weight reduction is directly related to the efficiency of the aircraft, therefore reducing fuel consumption, operational costs, power requirements and the level of emissions.

From a certification point of view, the qualification of new materials and seting up their manufacturing process will launch the technology to TRL9 in short time, which will reduce the time to market of the new materials evaluated in this project.
Specimen manufacturing
Project logo
Specimen testing