  This paper presents a large 6~m x 3~m aperture 7200 MEMS microphone array.
The array is designed so that sub-arrays with optimized point spread functions
can be used for beamforming and thus, enable the research of source directivity
in wind tunnel facilities. The total array consists of modular 800 microphone
panels, each consisting of four unique PCB board designs. This modular
architecture allows for the time-synchronized measurement of an arbitrary
number of panels and thus, aperture size and total number of sensors. The
panels can be installed without a gap so that the array's microphone pattern
avoids high sidelobes in the point spread function. The array's capabilities
are evaluated on a 1:9.5 airframe half model in an open wind tunnel at DNW-NWB.
The total source emission is quantified and the directivity is evaluated with
beamforming. Additional far-field microphones are employed to validate the
results.
