Since any penetration time was directly proportional to the in-cloud exposure and since suitable proportional corrections could be made for different sampling altitudes and airspeeds, curves were used to determine quickly either sampling capability or required in-cloud exposure. It was assumed, for example, that sampling missions were to be planned within a limit of 3.9 roentgens total radiation exposure using F-8lG aircraft for two nuclear explosions having predicted yields such that the sampling altitude was determined to be 35,000 feet. Typical requirements were as follows: (a) For the first explosion each sample should contain on the average, an amount of material (FE) equivalent to 1 x 107° kilotons, (b) For the second device the smallest sample size should average 1x107" kilotons and this amount should be exceeded if possible. (c) For each explosion should be expected differences in the amount collected by individual aircraft from that required if these differences were within the probable relative error, Since the probable sampling altitude assumed was that used for the F-8)G curve, it could be used directly to determine the in-cloud exposures required for these missions, At the two-hour "optimm" penetration time, simple proportion indicated that 0.175 roentgen was required to collect the sample for the first test while 1.75 roentgens was required to obtain the minimum amount desired in the second explosion, The total in-cloud exposure for both missions was the sum of these exposures or 1,925 roentgens, 3 210 AFWi/ito SWEH-2~0034 yo ewe