1. Four B-36 aircraft. (a) Two B36 Featherweights for obtaining high altitude particulate and gas samples. (>) One B~36D for measuring blast, gust, and thermal effects on aircraft in flight. (c) One RB-36 for the primary purpose of aircraft control and secondary purpose of photography. 2. Fifteen F-84G aircraft for particulate and gas sampling. 3. Three C-54 aircraft for photography. 4. Seven H-19 helicopters for certain ground sampling recovery and general logistic support. In October, some consideration was still being give to the possibility of utilizing the B-57 as a sampler aircraft during CASTLE. Following more study of that aircraft's capabilities, CTG 7.4 outlined several reasons why it would not be practical for use. The aircraft had developed an eight~cycle buffet at .72 Mach; it still wallowed considerably at altitude; its ceiling was 48,600 feet which was well below the required altitude for sampling; cer- tain engine difficulties had been experienced; it had limited range, making flight from the West Coast to Hawaii impossible; and, finally, mission-required modifications would be difficult to effect. In view of the above all thought of using the B-57 in CASTLE was abandoned unless further tests proved more successful. A companion problem to that above was the one of flight safety. 93