Supporting system interference on aerodynamic characteristics of an aircraft model in a low-speed wind tunnel

Many kinds of support system, such as tail support system, external/balance support system, side wall support system and wing tip support system are used for wind tunnel testing. The difference between the flow around the test model and the flow around the real aircraft is caused by the support system and results in a difference between aerodynamic characteristics of the test article and the actual one and is referred to as support interference. Support interference is one of the important topics of aerodynamic testing since it can have significant influence on the accuracy of the test data. The support system and support interference become one of the main investigation areas of experiment aerodynamics. The results of experimental investigation of the influence of model support on the determination of aerodynamic coefficients of a wind tunnel model are presented. A discussion is given of the forms of interference occurring in the low speed wind tunnel of the Military Technical Institute due to the model support system. Two types of model attachments, bent sting and external/balance model support are considered. The magnitude of interference on the test results is given. The main interference is on the pitching moment coefficient Cm. The computational results of the interference-free aerodynamic coefficients of a Training Aircraft Model are also given and compared to experimental data. A procedure for eliminating the undesired effect of interference of the model support system on the test results is presented.