The ARA Model Deformation Measurement System (MDM) is based around the hardware and software used within the ARA PIV system. The model is viewed by two SCMOS cameras from two different angles, a speckle pattern is applied to the model surface and images are captured wind-on and wind-off. Calibration is achieved using images captured of a calibration plate either before or after the run. These are then used in the post-processing to calculate the model shape before and during the run, allowing calulations of deflection and twist to be performed. Accuracy will vary depending upon set-up and calibrations but should typically be sub-millimetre.
ARA has also developed a Pressure Interpolation methodology which can be used to provide predictions of the model deformation based on the surface pressures recorded during the run.