The operational envelope that constrains the landing of a helicopter on a ship at sea is normally developed by expensive first-of-class flight trials. This paper describes the development of an experimentally-based simulation method that is intended to complement flight testing and mitigate its cost. The basis of the methodology lies with establishing correlations of unsteady aerodynamic fuselage loads with pilot workload, assessed for cases where airwake turbulence is chiefly responsible for the workload. With these correlations, contours of unsteady fuselage loading can assist with the definition of the helicopter's operational envelope. An experiment was conducted to measure the unsteady aerodynamic fuselage loads in a wind tunnel. In this investigation, the fuselage of a helicopter was immersed in both the downwash of a spinning main rotor and in the airwake of a frigate. Measurements of unsteady side and drag force, and yawing moment were made over a combination of wind directions, speeds, and hover positions. The results indicate that a spinning main rotor generating appropriate levels of thrust is a necessary feature of the wind-tunnel simulation. Generally the unsteady loading increases with the additional influence of main rotor downwash compared to the baseline, rotorless case. Specifically, in comparison to the rotorless case unsteady loading at low hover over the flight deck was found to increase to the levels of unsteadiness that exist at high hover, and the variation of unsteady loading with wind speed is changed by the interaction of the ship airwake and rotor downwash. In most cases, the wind tunnel data are shown to correlate well with flight-test derived operational limits.
Wind tunnel testing of a helicopter fuselage and rotor in a ship airwake
Windkanal-Simulation eines Helikopters im Windschatten eines Schiffs
Journal of the American Helicopter Society ; 50 , 4 ; 326-337
2005
12 Seiten, 15 Bilder, 13 Quellen
Aufsatz (Zeitschrift)
Englisch
Arbeitsbelastung , Betriebsbereich , Flugsimulation , Flugzeugrumpf , Hubschrauber , instationäre Strömung , Landung , Luftströmung , manuelle Steuerung , Nachlaufströmung , Rotor (Drehflügel) , Schiff , Schweben , Windbelastung , Windkanalprüfung , Strömungsrichtung , Windgeschwindigkeit , dynamische Belastung , Modellversuch
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