While vortex ring state (VRS) is a much-publicized phenomenon, its boundaries have not been well understood, nor have they been accurately verified and documented, until recently. Substantial analysis and laboratory testing has attempted to determine VRS boundaries, with widely varying results. Some researchers hypothesize that VRS is entered whenever a hovering rotor begins to descend. However, flight test results on a variety of helicopters indicate that VRS doesn't significantly impact rotor response and aircraft control until the relative vertical velocity of the rotor equals approximately one-third to one-half of the hover-induced velocity predicted by the simple momentum theory. At these descent rates, the deterioration of the formerly well-defined wake slipstream yields a variety of progressively worsening characteristics, beginning with high vibrations, thrust fluctuations, and eventually leading to degraded thrust control and cyclic control. This paper presents an extensive flight test program that has been conducted to evaluate the effects of Vortex Ring State (VRS) on the V-22. Since there was no existing flight data on tiltrotors with respect to VRS, a methodical buildup approach was used during the test program. Over a three year period, the V-22 Integrated Test Team (ITT) conducted progressive flights of the V-22 deep into fully developed VRS. Initial testing involved defining the static, or, steady state VRS boundary. During this test phase, aircraft controllability well beyond typical operational limits and a consistently effective recovery technique were demonstrated. Subsequent testing demonstrated dynamic maneuvers that penetrated the steady-state VRS boundary by first expanding to aggressive single axis maneuvers, and then progressing to multi-axis maneuvers. Test results show that the V-22 provides increased sink-rate margin for avoiding VRS, when compared to conventional helicopters.


    Zugriff

    Zugriff über TIB

    Verfügbarkeit in meiner Bibliothek prüfen


    Exportieren, teilen und zitieren



    Titel :

    V-22 low-speed/high rate of descent (HROD) test results


    Weitere Titelangaben:

    V-22 Flugversuchsergebnisse für Langsamflug bei großen Sinkraten


    Beteiligte:
    Kisor, Ron (Autor:in) / Blyth, Robert (Autor:in)

    Erschienen in:

    Erscheinungsdatum :

    2004


    Format / Umfang :

    23 Seiten, 21 Bilder, 2 Tabellen, 27 Quellen


    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch




    Descent Advisor preliminary field test

    Green, Steven / Vivona, Robert / Sanford, Beverly | AIAA | 1995


    Descent Advisor Preliminary Field Test

    S. M. Green / R. A. Vivona / B. Sanford | NTIS | 1995


    Simulation Test Of Descent Advisor

    Davis, Thomas J. / Green, Steven M. | NTRS | 1991


    High-Speed, High-Temperature Finger Seal Test Results

    Proctor, M.P. | Online Contents | 2004


    Descent advisor preliminary field test

    Green, Steven M. / Vivona, Robert A. / Sanford, Beverly | NTRS | 1995