Published online by Cambridge University Press: 04 July 2016
Until a few years ago it was the practice to neglect lift interference on oscillatory model tests in high-speed subsonic wind tunnels, whatever the working section configuration. However, in 1960 Bratt and Wight discovered a large interference effect on the pitch damping derivative of an M-wing measured in the slotted working section of the 25 in x 20 in tunnel at the National Physical Laboratory. In 1964 Wight reviewed a number of oscillatory tests and showed that in many cases there were significant interference effects on both stiffness and damping derivatives when measured in slotted working sections.