Advances in computational methods are producing a need for accurate and detailed experimental results for test cases. At the same time economic trends force many of these experiments to be made in small wind tunnels. In some cases the small scale of the model does not provide enough space for the instrumentation and so the model must be distorted from the ideal shape. This paper is concerned with one aspect of this problem, that is, with the need to make wings thicker than required, either for strength or to provide volume for pressure tubes and other measuring devices. In particular the paper deals with the conditions under which the pressures measured on the flat surfaces of wings with bevelled or triangular cross-sections as shown in Figs. 1(b) and 1(c) are a good representation of the pressures which would be measured on the corresponding flat surface of thin wings (Fig. 1(a)). This problem has been touched on in a number of papers reporting experimental results but it does not appear to have been tackled systematically. The discussion of this paper is based on these earlier tests and on some new test results.