Airbus to test laminar-flow wing sections on A340

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Airbus is working on experimental laminar-flow wing sections, which it aims to install on a company-owned A340-300 for test flights due to begin in 2014.

The 'Smart Fixed Wing Aircraft Integrated Technology Demonstrator' will involve the replacement of a 8.5m (27.8ft) section of the existing wing from the outboard engines to the wing-tip on both sides of the aircraft.

This project is part of Europe's 'Clean Sky' research programme and is being jointly pursued by the airframe, Saab and other partners.

The two wing sections on either side of the aircraft, MSN001, will be different in their structure and, potentially, material selection in order to determine the most suitable manufacturing principle.

Both will largely be made of carbonfibre-reinforced plastic (CFRP). However, the forward part of the starboard wing section will be produced as a single, integrated component comprising the composite surface, leading edge and interior structure, while the respective section on the port side is to be constructed out of individual surface and structural parts. This could include a metallic leading edge.

The laminar section of the experimental wing comprises the leading edge and upper surface approximately 60% along the chord length. The remaining part of the wing will not have laminar characteristics as the flight-control surfaces along the trailing edge - ailerons in case of the respective outer wing section - disrupt the airflow through their movement and gaps in the wing surface.

Theoretically, a laminar wing could reduce drag by up to 85% but the actual savings under real conditions will be lower as the final design would need to be a compromise between different competing constraints such as aerodynamic and structural requirements. The target is to develop and mature a wing with friction drag reduced by 25% compared with a conventional design.

Airbus programme leader Jens Koenig says the challenge is to find the optimal balance between an efficient, yet aerodynamically-robust wing.

Insects accumulating on the leading edge, for example, are a major irritation as they disturb the laminar airflow. The same is true for rivets, which complicates the assembly of the port wing from individual parts.