These images show the noise field of a propeller or rotor at incidence. The field is calculated using a similar method to that developed for propellers in forward flight. The plots show pressure in the rotor plane for a conventional propeller at takeoff (angle of attack 20 degrees) and a helicopter rotor (angle of attack 85 degrees). In both cases, the flight Mach number Mfl=0.2 and the tip rotational Mach number Mtip=0.8. A paper describing the method has been submitted to the Journal of Sound and Vibration
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| Mtip=0.8, Mfl=0.2, incidence 20 degrees | Mtip=0.8, Mfl=0.2, incidence 85 degrees |
This figure shows the field around a rotor with tip Mach number 1.5 in a flow (from bottom to top of the figure) of Mach number 0.2
