What corrections are applied to wind tunnel data and why?

Wind tunnel corrections account for differences between tunnel and free flight conditions: Wall corrections adjust for blockage (solid and wake) that increases effective velocity, streamline curvature from walls affecting lift/pitching moment, and wall interference with tip vortices; Support interference corrections remove sting or strut effects; Reynolds number corrections scale data from tunnel to flight conditions; Mach number calibrations ensure accurate freestream conditions. Corrections can be 5-15% of measured forces. Modern facilities use adaptive walls or computational corrections for improved accuracy.