Europe's Clean Sky joint technology initiative to reduce air transport’s environmental footprint continues to progress as various bits of demonstration equipment are coming closer to making first flights.
In Sweden, Saab has completed a natural-laminar-flow wing section, designed to reduce drag. Part of the Blade (Breakthrough Laminar Aircraft Demonstrator in Europe) flight demonstrator, it will soon arrive at Spain’s Aernnova for the assembly phase of the wing. Airbus plans eventually to install it on its A340-300 MSN001 flight-test aircraft.
Engineers designed the demonstrator to increase the length of the airflow that remains laminar (as opposed to turbulent) over the wing. Therefore, they must get rid of the fasteners that usually appear on the upper skin, ensuring optimal smoothness. A major contributor to reducing the number of fasteners involves attaching the leading edge to the rest of the wing skin. Rivets usually go through the skin, down to the substructure, explained Saab engineering manager Jonas Bohlin.
On Blade, Saab has integrated the leading edge with the spar and the stringers in a single, co-cured composite architecture. The points that attach the panel to the wing box form part of the underside of the wing skin. As a result, on the outer surface, no fastener or gap will disturb the flow. The carbon-fiber subassembly will form part of the left wing of the Blade flight demonstrator.
“We have also reduced weight and cost by using the latest knowledge in composite design and manufacturing,” said Dan Jangblad, Saab’s head of industrial products and services.
The technology, if applied to the entire wing, could bring an estimated 5- to 10 percent improvement in fuel burn.
Meanwhile, in Munich, MTU Aero Engines continues to run an advanced geared turbofan in a test cell. According to the company, it will “show the maturity of the newly developed technologies for low-weight constructions, designs and materials that will help increase the efficiency of future geared turbofans and at the same time reduce emissions and noise.” MTU’s efforts center on the low-pressure turbine, which runs faster in a geared turbofan than in a conventional engine. GKN Aerospace Engine Systems in Sweden developed and supplied the turbine exit case. The new technologies went into a PurePower PW1500G geared turbofan engine made available by Pratt & Whitney, which has taken the opportunity to test a new shaft.