EY EY FSRaROY F es 2 FS 2> . Bs 1 & . i es a given measured value of AP/P,, the way in which the average sound velocity is defined is not particularly critical when only moderate accuracy is required since c varies by only 14 to 15 per cent between sea level and the tropopause. For the present purpose & is taken to be - (z) z-h [ret (A.3) where z is the altitude of the gauge and h is that of the bomb. This function has been computed from the meteorological data for each shot by aumerical integration. The effect of wind has been taken into consideration by adding to the average shock veloc- ity the average component of wind velocity, Wy, projected onto the line from shot to gauge (assumed to be along the flight path of the dropping aircraft). Since the wind component represents only a relatively small correction to the average shock velocity, the way in which the average is defined is not critical. In the present case the average has been computed by weighting the wind velocity in each small incrementin altitude in propostion to the time that would be taken by a sound wave in passing through the given increment of altitude. The numerical values used in the computation of slant ranges are tabulated in Tables A.l and A.2. Since this procedure for computing the slant ranye assumes rectilinear propagation from source to gauge, with the normal free-air decay of peak overpressure with distance, it is strictly applicable only to the direct shock in the reg‘on of regular reflection or to the case of a surface burst, where the direct and reflected shocks coincide from the start. However, at points that are not too close to the triple point and at distances large compered to the height of burst, the peak overpressure in the Mach stem does not appear to differ greatly from that which would result from a surface burst; therefore the present method should give a reasonably good approximation for the slant range in such cases also. Since the canisters that fell ii the Mach region on King shot were all far from the path of the triple point, the slant ranges computed Table A.1—AVERAGS SHOCK VELOCITY, MIKE SHOT ‘ ; F z Hi k Canister No. SP/P, V/t t, ft/sec V, {ft/sec Wp, ft/sec V+We 2 3 4 5 1 8 9 0.929 0.861 0.138 6.088 1.919 0.515 0.212 2.398 2.324 1.358 1.273 3.235 1.988 1,492 1118 1117 1114 1110 1128 1126 1127 2681 2596 1511 1413 3649 2238 1681 -17 —18 —22 -22 -17 ~19 —20 2664 2578 1489 1391 3632 2219 1661 10 11 0.0656 OAM 1.199 1.300 1120 1120 1456 ~21 -21 1322 12 0.0341 1.119 1113 £245 ~22 1223 1343 1435 from the travel times to these canisters are considered to be sufficiently accurate for the purpose of this report. In Project 1.1 of Operation Snapper, Shot No. 8, the slant ranges were deter’-‘ned both from travel times and by an electrcnic multiple-object tracking systém (MOTS). The percentage difference between the MOTS and travel-time ranges had a root-mean-square value of 3.6 per cent and an algebraic mean difference of 2.2 per cent, the travel-time ranges being the larger on the average. i Bed Sete DAraeaEeeeok \ 42 RESTRICTED DATA -i- SECURITY INFORMATION