The Natural Laminar Flow (NLF) aerofoil is a potential key technology for the next generation of aircraft, improving aerodynamic performance, and thus reducing drag, and hence emissions. Achieving these reductions would be a significant step towards reaching the ACARE goals for 2020, including a 50% reduction in CO2 emissions and an 80% reduction in NOx emissions.
The requirements of a Natural laminar flow wing differ significantly from a conventional turbulent wing, requiring changes to both the architecture of the wing, the aerofoil definition and the detailed design and manufacturing concepts. The performance of a natural laminar flow wing requires very tight surface roughness and waviness tolerances and contamination free surfaces in the areas where laminar flow is to be maintained. NLF wings also require alternative Leading Edge (LE) moveable concepts, novel LE/Wingbox joints, and slender LE sections.
In Phase 1 of the Ground Based Structure and Systems Demonstrator (GBSSD) programme, the problem of how to achieve an aerodynamic surface of sufficient quality to support natural laminar flow had been addressed by GKN.
Phase 2 was being undertaken by GKN and involved the detailed design of the fully integrated LE zone and forms the basis for the further development of the concepts for the GBSSD.
Phase 3 involved the manufacture of all selected features, components and sub-systems that enabled the several functions of the LE assembly and sub-systems to be demonstrated. These features were supplied to Clean Sky to support the assembly of a 4.5m spanwise section of leading edge installation, including components and sub-systems. The demonstrator aimed to validate that the Phase 2 LE design can be manufactured in realistic high rate and repeatable conditions appropriate to a civil short range aircraft to the required level of aerodynamic surface quality to achieve laminar flow.
The GBSSD3 program was an ongoing area of research aimed at developing the capability and understanding of Natural Laminar Flow (NLF) for the next generation of civil aircraft. It is undertaken in support of the Smart Fixed Wing Aircraft (SFWA) program to mature a NLF technology stream for a future short range transport aircraft and is intended to support the TRL process by the design, manufacture, test and demonstration of an integrated NLF wing leading edge assembly, as a Ground Based Demonstrator (GBD).
The NLF aerofoil coupled with improved aero-smoothness, offers higher efficiencies in aerodynamic performance and a reduction in drag, contributing to an overall increase in an aircraft’s efficiency. This in turn allowed for potential reductions in aircraft emissions by reducing fuel burn. Achieving these reductions were a significant step towards reaching the ACARE goals for 2020, including a 50% reduction in CO2 emissions and an 80% reduction in NO emissions.
The requirements of a NLF wing differ significantly from a conventional turbulent wing, requiring changes to the architecture of the wing, the aerofoil definition, the detailed design concepts and manufacturing processes. The aerodynamic performance of a natural laminar flow wing is highly dependent on meeting very high aero-smoothness tolerances including steps and gaps, surface roughness and surface waviness tolerances, in the regions where laminar flow is to be maintained.