GRA - Objectives & Status
Main goals for the GRA are to allow the reduction of CO2, NOx and noise emissions and contribute to the achievement of the ACARE 2020 environmental targets. These targets are the results of the introduction exclusively of new airframe technologies in the next generation green A/C. For example large improvement on environmental impact are expected in aerodynamics not only for drag reduction (laminar flow, turbulent skin friction) but also for noise reduction. An another important area is airframe weights, since the regional A/C has an empty weight (OEW) that is a larger fraction of the mission weight than other types of aircraft. OEW counts significantly on fuel consumption and therefore on emissions during all phases of the mission.
In summary the main top level GRA tasks are to demonstrate technologies for future regional aircraft aiming at the reduction of fuel consumption, pollution and external noise. These goals will be achieved by means of mature, validated and demonstrated technologies in the aerodynamics and acoustics (Low Noise domain), structures and materials (Low Weight domain), all electric aircraft architectures (All Electric domain), avionics architectures (Mission Trajectories Management domain).
Integration of these new technologies in advanced aircraft configurations interfacing the advanced green powerplants types (New Configurations domain) is the other fundamental pillar of GRA approach, together with the achievement of fully integrated technical solutions with other technical platforms (energy management, mission & trajectory managements from SGO, engines from SAGE and material and industrial processes from Eco-Design), and other important European Commission programs aimed to improve air transport system like SESAR.
GRA technological areas are structured as follows:
GRA1 - Low Weight Configuration (LWC)
GRA2 - Low Noise Configuration (LNC)
GRA3 - All Electric Aircraft (AEA)
GRA4 - Mission & Trajectory Management (MTM)
GRA5 - New Configuration (NC)
This structure is well reflecting its transversal nature by being organized in 5 domains, that in turn interface with the other JTI platforms.
The GRA1 Domain, which deals mostly with structures, after the down-selection process of the technologies matured in the first part of the program, will proceed through theoretical studies supported by advanced modeling tools and extensive small-medium size structural tests. Demonstration is envisaged on ground, on full scale representative assemblies of wing and fuselage sections, and in-flight, replacing selected components of an existing regional aircraft with the LWC developed advanced solutions.
The GRA2 Domain deals mostly with aerodynamics and aero-acoustics aspects. The down-selection process of the addressed technologies is planned to be carried out through large-scale wind-tunnel tests on A/C configurations models. Natural Laminar Flow will be investigated as main technology for drag reduction , in particular with respect to regional A/C applications, with a focus on new techniques for HLD devices both for low noise features and less impact on laminar wing. Small scale development tests up to larger scale will be used together with extensive application of CFD tools.
The GRA3 Domain, which deals mostly with systems, will explore the possibility to remove (bleed-less) or minimize the extraction of pneumatic power (from the engine) and the usage of hydraulic power. Indeed GRA3 foresees the development of relevant data through dedicated studies, simulations and tests, and a meaningful in-flight demonstration of some of the most critical sub-systems, e.g. the electric environmental control system (E-ECS), the ice protection system (E-WIPS), and some energy management (EM) concepts.
In the future important benefits, in terms of environmental impact, are envisaged from the evolution of GRA4 domain (Mission and Trajectory Management) for regional aircraft. The aim of this domain is to demonstrate optimized missions and trajectories tailored to the characteristics of regional aircraft.
MTM activities has been performed in the definition of regional aircraft high level requirements and MTM peculiar functionalities In fact, the following objectives have been achieved: definition of regional a/c requirements and MTM functionalities, definition of operational scenario and evaluation of safety aspects and definition of GRA flight simulator architecture.
In GRA5 domain comprehensive high level requirements (including power-plant) of a regional aircraft will be developed. Starting from that, a complete set of system engineering requirements and technical specifications will be derived and, trade-off studies will be performed for the assessment of the aircraft general architectures and performance that are the “best fit” with respect to the GRA environmental forecast. Studies will start from the reference configurations of modern regional aircraft flying in the year 2000 (take as reference aircrafts) and will then concentrate on the integration of the different types of advanced power-plant, fitting to regional aircraft high level requirements, and subsequently on the integration of the peculiar technologies developed in the other GRA domains.
Final demonstrations for Low Noise and New configuration domains will consist of a large scale aerodynamic and aero-acoustic wind tunnel test campaign that will assess the performance of the aircraft configuration selected at the end of the process.
In-flight testing of selected concepts/solutions will be also envisaged, tailored to the features and performance of the flight demonstrator.