Investigation of the wear properties of a riblet paint structure on an airbus A300-600ST Beluga

While the application of drag reducing riblets on aircraft in the past was done by an adhesive film, a new promising technique was developed by the Fraunhofer Institute IFAM. The riblets are imprinted very precisely into the paint on the aircraft. To investigate the durability of such a riblet structure, free flight tests on an Airbus A300-600ST Beluga were performed. According to a specified time schedule, samples from the aircraft were taken. This riblet samples were prepared to measure the aerodynamic properties in an appropriate test facility, the DLR oil channel. The preparation of the test samples consists of several steps like moulding, casting, three dimensional surface measurements and a rapid prototyping technique. The sample preparation chain is evaluated by means of a common numerical method. Results of the experimental investigation show the influence of the wear during the flight tests on the riblet surface.