The occurrence of self-excited vibrations of an elastic aircraft flying faster than a certain critical airspeed is called 'flutter'. The subject of this publication is the improvement of the current procedures for the demonstration of freedom from flutter of gliders during flight vibration tests. After an analysis of the state of the art of flight vibration test techniques, the problems especially occurring during tests of gliders are investigated and judged. Special glider suited test equipment is developed to meet the problems resulting from excitation by hand. The equipment consists of an exciter system and a measurement system. It allows for a well defined excitation of the glider in order to extract the system parameters relevant for flutter safety from the measured response. Two exciters usually connected to the wings produce aerodynamic forces by means of a small additional rectangular vane pitching about its quarter chord. The exciters are synchronised by a control unit to allow for the symmetric or antisymmetric excitation of the aeroplane. The effects of the test equipment and the test procedures on the critical airspeed prediction are investigated using two-dimensional simulations, finite element calculations and flutter calculations for a finite element model representative for gliders. Flight vibration tests with three different aircraft are carried out in order to support the theoretical results. Recommendations for the future development of flight vibration testing of gliders are derived from the findings. This investigation improves the flight flutter test technique of gliders based on scientific investigations and so improves their safety.


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    Titel :

    Ein Beitrag zur Überprüfung der Flattersicherheit von Segelflugzeugen durch instrumentierte Flugschwingversuche


    Weitere Titelangaben:

    A contribution to review the safety of gliders against flutter by instrument based in-flight vibrational tests


    Beteiligte:
    Brendes, G. (Autor:in)

    Erschienen in:

    Erscheinungsdatum :

    2001


    Format / Umfang :

    167 Seiten, 96 Bilder, 1 Tabelle, 122 Quellen




    Medientyp :

    Hochschulschrift


    Format :

    Print


    Sprache :

    Deutsch