Targeting a 5% cut in an aeroplane’s CO2 emissions by reducing wing friction, Airbus has successfully completed the maiden flight of its A340 laminar-flow “BLADE” test demonstrator aircraft. BLADE stands for “Breakthrough Laminar Aircraft Demonstrator in Europe” and is part of an EU-sponsored Clean Sky project to improve aviation’s ecological footprint.
The Airbus A340 used for the test — dubbed “Flight Lab” because it is the first aircraft in the world to combine a transonic laminar wing profile with a true internal primary structure — took off from the Tarbes aerodrome in southern France and flew for just over three and a half hours before landing at Airbus’ facilities in Toulouse Blagnac.
On the outside, the aircraft is fitted with two representative transonic laminar outer-wings that are intended to reduce wing friction by 50%; while inside the cabin a highly complex specialist flight-test-instrumentation (FTI) station has been installed.
The maiden flight marks the start of an Airbus programme to explore the wing’s characteristics in flight, according to Flight-Test Engineer Philippe Seve: “We began by opening the flight envelope to check that the aircraft was handled correctly. We achieved our objective to fly at the design Mach number, at a reasonable altitude and check everything was fine. We also checked that the FTI was working as expected, to identify further fine-tuning for the next flights.”
The highly modified A340-300 test-bed aircraft has been developed over the course of 16 months by an Airbus team in Tarbes, with the support of numerous industrial partners across Europe.
Initially, a small team of 10 specially trained pilots, test engineers and flight test engineers had prepared for the milestone for several months, spending time in a simulator and familiarising themselves with the FTI systems to be installed on the Airbus flight-test aircraft. In all some 70 people performed the FTI installation inside the aircraft, while teams from Bremen, Germany, and Broughton, UK, worked on the outer wings, with a team from Stade Germany, installing a pod containing infrared cameras on the fin.
Breaking new ground for Airbus, the wings feature hundreds of points to measure the waviness of the surface, which will help Airbus’ engineers ascertain its influence on the laminarity. Other “firsts” are the use of infrared cameras inside the pod to measure wing temperature and an acoustic generator that measures the influence of acoustics on laminarity. In addition, there is also an innovative reflectometry system, which measures overall deformation in real-time during flight.
A key goal of Blade is to be able to measure the tolerances and imperfections, which can be present and still sustain laminarity. To this end, Airbus will simulate every type of imperfection in a controlled manner, so that at the end of the campaign the tolerances for building a laminar wing will be fully known. The flight Lab will perform around 150 flight hours in the coming months.