The study is devoted to measurements of heat flux with an external high speed gas flow around the axisymmetric model. Sensors based on bismuth anisotropic thermoelements were used. Experiments were carried out using Big  Shock Tube. The models used for experiments were the combinations of a cone with an opening angle of 60 degrees and a cylinder. The models with heat flux sensors were placed in the outer section of the flat supersonic nozzle. The results were compared with theoretical estimates made using the effective length method. The data obtained demonstrate the applicability of sensors in gas-dynamic experiments with test times about 1 ms.