AO we < (HURON) Project 11.2 - Sampling ~ H. F, Plank Sampling for os shot was essentially routine and proceeded as outl in Program 11's Standard Cloud Sampling Mission Plans for REDWING, H. F. Pla 16 April 1956, 11740FE, page 29. Two F-84G aircraft were used in loose trai formation in place of the single B-57B sampler at the lowest altitude previo specified so that a special glass fiber filter paper could be tested. Becau of its lower resistance to air flow with the fiber glass material, the alpha rr) cellulose filter paper in the other filter unit collected 3.8 times more, debris. bom 1 A special effort was made to reduce cross-contamination from the preced shotein the allowed 24 hour period so that the radiochemical analysga@pents oi would not be compromised. The preceding shot was a — device, A compromise procedure for decontaminating the B-57B filter units consi of removing the valve sections, scrub-washing their exposed surfaces and tho the diffuser section while disassembled. The unit was washed and rinsed twi more after the valve section was re-assembled. Any cross-contanination whic be seen in the samples must come from the fallout which occurred during clea operations. Although numerous cumlo-nimbus clouds and considerable cirrus were pre during and after shot time, the cloud was sufficiently visible for the recon sance aircraft to determine that the altitude of the active stem was appraci 17,000 feet and for the highest aircraft to determine that the top of the ma cloud was approximately 52,000 feet indicated pressure altitude, pien100E Ga RE - 36 orn Sampling w