Measurement of transient loads on two models

Abstract

The T-38 wind tunnel is a blow down, intermittent-run type of wind tunnels. During model testing in the this type of wind tunnels, at Mach numbers higher than 2, transient loads which appear during the starting and stopping of the wind tunnel runs must be taken into consideration. These are the conditions when a model and the wind tunnel balance are exposed to large aerodynamic forces and moments. These combined loads can damage models and wind tunnel balances, and, for this reason, it is very important to determine them in advance for any particular model configuration so that an appropriate wind tunnel balance and materials for model manufacturing can be chosen. For that purpose there are graphs which give possibilities to estimate these loads. The graphs are based on experiments with a number of different models at Mach numbers higher than 2. This paper gives the measurements of transient loads on two more models and the results are compared with the already existing graphs. .