Table 9—- RESULTS OF KING SHOT REDUCED TO 1 KT (RC) AT SEA LEV EL Station Distance to ground zero, Slant range, No. ft ft 617.01 617.02 617.03 617.04 617.05 617.06 617.07 617.08 612.02* 612.02f 6101.01 6101.02 6101.03 6101.04 Y 365.9 \%% 407.0 426.1 \Sb 461.9 546.4 \8* 574.9 Time of arrival, sec 0.095 0.117 0.172 667.0 787.5 908.0 1270 1869 6649 %-> 690.4 +462 807.5 30% 925.5 42% 1282 3 1877 2b 6651 0.235 0.307 0.384 0.636 1.094 5.118 417.0 662.1 904.7 1229 \34 453.6 2! 685.7 tel 922.1 Abo 1242 0.097 0.215 0.376 0.598 6649 2ub66s1 5.119 *Side-on baffle. s* + Pitot static tube. 7 CONCLUSIONS AND RECOMMENDATIONS Aside from the fact that no data were obtained at pressure levels greater than 20 psi on Mike shot, gauge and recorder failures did not pose any insurmountable problem so far as the over-all objectives of the program to measure air-blast pressures on Operation Ivy were concerned. As it turned out, the sensitivity of the Ampex recording system to acceleration did not seriously hamper analysis of the data received. Someof the difficulties were resolved between shots, and others are in the process of being corrected. Especial care should be exercised to eliminate the zero-drift characteristics of the Ampex recording system if it is to be used on future measurementsof this type. Analysis of the data from Mike and King shots led to the following conclusions: 1. Use of the cube root scaling law to scale distances and times of arrival appears to be valid for radiochemical yields as great as 10 Mt. 2. Overpressures from Mike shot are evidently in agreement with the assumptionthat the overpressures to be expected from a yield, W, burst at the surface of a perfect reflector, are the same as would be observed from a yield of 2W, burstin free air. 3. Pressures at distances equivalent to the height of the atmosphere are apparently attenuated considerably as a result of the effects of a nonhomogeneous atmosphere. 4. Agreement of the pressures from Mike and King shots with the isobars on the height- of-burst chart published in TM 23-200 is considered ample justification for extending the ap- plicability of this chart to y:elds of the order of 500 Kt. The correction factor used in conStructing the original isobars to take into account the thermal effect would seem to be quite valid as corroborated by the results obtained on the land blast line for King shot. 5. Although there was no evidence of the thermal effect on Mike shot, it is possible that a thermal effect would have been noted had the burst been entirely over land. On King shot a thermal effect was definitely observed in measurements made on the land line, but sharp rise times were obtained over water. 6. Findings regarding attenuation of positive impulse over land more or less 20Neleted./ 1 Kages SG They 60