Wind-tunnel tests of aeroelastically designed helicopter rotor models were conducted to obtain rotor aerodynamic performance and dynamic response data per-taining to two-bladed teetering rotors with a wider chord (1.47 m (58 in.)) and lower hover tip speed (195 m/s (640 ft/sec)) than currently employed on produc¬tion helicopters. The effects of a flapping hinge at 62 percent radius were also studied. Finally, the effects of changing tip mass on operating character¬istics of the rotor with-the outboard flapping hinge were examined. The models were tested at several shaft angles of attack for five advance ratios, 0.15, 0.25, 0.35, 0.40, and 0.45. For each combination of shaft angle and advance ratio, the rotor lift was varied over a wide range to include simulated maneu¬ver conditions.nAt each test condition, rotor aerodynamic performance and dynamic response data were obtained. From these tests, it was found that wide-chord rotors may be subject to large control forces. An outboard flapping hinge may be used to reduce beamwise bending moments over a significant part of the blade radius without significantly affecting the chordwise bending moments. Increasing the tip mass was found to be an effective tool in restraining the flapping motions of the blade outboard of the hinge. The criteria for selecting outboard hinge location and tip mass must also include consideration of the effects of these parameters on rotor blade natural frequency.
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