"Velocity measurement." . . "Separated flow." . . "Unsteady flow." . . "Velocity distribution." . . . . . . . . . . "Unsteady velocity measurements taken behind a model helicopter rotor hub in forward flight" . "Unsteady velocity measurements taken behind a model helicopter rotor hub in forward flight"@en . . . . . . . . . . . . . . . . . . . . . "Helicopters." . . . . "Turbulence effects." . . "Wind tunnel tests." . . "Aerodynamic configurations." . . "Horizontal flight." . .