were quite distorted and non-ideal in character, as shown {n Figure 2.2. All of these gage stations were located near the edge of the water, except for the measurement on Shot 6 which was preceded by some 600 feet of blast travel over an island surface; the latter record showed only a slightly rounded wave form with a peak dynamic pressure in good agreement with that value computed from the measured overpressure. For those dynaric pressures measured near the edge of the water, it was assumed that the blast wave picked up water droplets which contributed to the disturbed appearance of the wave form and that water is not an ideal surface. The primary objective in taking dymamic-pressure measurements was 2 study of the pressure-time records to check the theoretical relation between dynamic pressure and TABLE 2.3 COMPARISON OF MEASURED AND CALCULATED VALUES OF DYNAMIC PRESSURE —" , Type of Gage pat pat pai 6 S/R* Pitot static im 168.0 138.0 0.83 6 S/R® Pitot statlo 32.8 19.6 23.5 1.20 4 é B/R®° Pitot static Diff pree q Drag q 4.3 23.2 23.3 11.7 10.7 11.7 138.0t 1.00 1.21 6 6 8/R* Pitot static Pitot statio 22.4 10.2 10.4 1.00 4 @ 6 8/R* Pitot statio S8/R* Pitot static 3/R°* Pitot statio 20.0 19.0 16.8 8.17 78 6.08 9.20 8.8 8.6 1.138 1.37 0.92 4 Of pres q 14.46 4.3 7.0t 1.83 4 Drag q 148 43 7St 1.74 3 3 3/R* Pitot static U/R* Pitot static 1.31 046 1.1 0.77 0.84 1.67 5 3 3 S/R* Pitot static S/R* Pitot static Caloaetns 10.7 21.0 8.8 7.62 443 3.20 3.28 0.34 0.25 sonmred Ratio of Measured q to Calculated q Sho: L3.3t 8.5 0.47 0.60 1.24 0.96 1.38 2.00 “S/R refers to salf~recording mechanica) gages of Project 1.2b (BRL). Al) other gages are electronic gages employed by Project 1.3 (BC). t Maximum value of q which fs indicated here ocourred at a later time than maximum value of Ap. overpressure. From a somewhat-limited quantity of data, it was found that the relation did not hold where the path of the blast wave approaching the gage station was over a water surface. Table 2.2 shows a comparison of measured and calculated values of dynamic pressure. 2.3.8 Dynamic Pressure ag a Damage Parameter. Jeeps were used as representative models to investigate further the role of dynamic pressure as the damage parameter to consider for drag-sensitive targets. Participation was planned for two shots, one of which was cancelled; actual participation was accomplished on Shots 3 and 6. The low yield of Shot 3 gave low dynamic pressures and consequent light damageto vehicles. Satisfactory damage—-light to severe -—was attained on Shct 6. The limited data obtained were not conclusive enough to permit an evaluation of dynamic pressure as a damage parameter to be applied to the jeep as a drag-~-sensitive target. The response of such a target depends on the loading, which is a function of both dynamic pressure and duration. The results obtained did not allow a separation of the effect of the one damage parameter from that of the other. Furthermore, it was not possible to determine specific levels of dynamic pressure for different degrees of damage. Consequently, it was difficult to justify the cube-roct 25