Comparison of Force Measurements in the HEG and T4 Shock Tunnels

The stress-wave force balance, which was developed in the T4 facility, was tested in the HEG shock tunnel. This balance is able to measure forces in sub-millisecond test times. In order to obtain a direct comparison the same model and balance were used in both facilities. The drag on a sharp cone with a 15 degree half angle was investigated for different test conditions which covered a range of 60 to 380 N total drag in T4 and 50 to 105 N in HEG. The measured drag was compared to theoretically predicted results and was found to be within the measurement accuracy of about 10% in T4. In HEG the level was somewhat higher at about 12%. It is concluded that the force balance is also capable of measuring forces in HEG to a similar level of accurac