Bottom drag measurements in experimental wind tunnel tests

The paper presents the results of wind tunnel tests aimed at determining the model bottom drag in the case of rocket model tests. The balance measurement technique of the rocket model fixed in the wind tunnel test section by the rear sting was discussed. The model was equipped with the two parallel boosters. Based on the wind tunnel test of the rocket twin model the values of the bottom pressure was determined for tested Mach numbers. An algorithm of wind tunnel corrections was shown, which allowed the total drag determination in a case of the rocket active or passive rocket flight. The test results showed the necessity of the bottom drag measurements in wind tunnel tests.