The M.I.T.-Wright Brothers WIND TUNNEL and its Operating Equipment 410128
WITH the M.I.T.-Wright Brothers wind tunnel and balance system, Prof. Markham explains, it is possible to obtain measurements very rapidly on a complete airplane model from which the coefficients for all six components can be plotted with a minimum of calculation. It is usually possible, he continues, to mount the model so that the point representing the center of gravity of the airplane is on the balance axis, a feature which increases the accuracy of the results and the simplicity of the calculations.
This balance system was designed to fulfill the following general specifications: It had to be compact for the pressure-type tunnel in which it operates requires that the shell surrounding the test section be kept to a minimum diameter; it should be arranged so that measurements of all six components could be made remotely and that angular settings of the model in pitch and yaw could be made from a remote station. It was required further that each component be measured independently and totally so as to simplify and shorten the numerical calculations.
The test section was made an ellipse in order to obtain as large a span-wise dimension as possible for a given test-section area. It is then possible without requiring extra power, to test a model with a larger span in an elliptical tunnel than in a tunnel of circular cross-section of the same area at the same speed.