xr Laboratory would not be required to stand any of the cost of procurement or modification,-© Headquarters, Task Croup 7.4, Provisional, assumed that the model would be available for use during PILGRIM, "Completely modified B-57D aircraft should be assigned to the organization for a minimum of four months before departure date for the Pacific Proving Ground," and officials listed the reasons for the four-month requirement, Colonel John S. Samuel, Commander, apparently did not know that the plane was not yet approved for use aS a Sampler, Additional arguments in favor of the B-57D came with the CHEROKEE Shot of Operation REDWING. During the shot, which was made at 5,000 feet altitude, the B-57B aircraft chalked up a near failure in obtaining samples. "The yield of the weapon is, therefore, known with less accuracy than might be desired," Dr Graves wrote to General Canterbury, "As a matter of direct observation," he continued, "very satisfactory samples probably could have been collected in a layer of bomb cloud which persisted at a 2,000 to 5,000 foot higher altitude than could be attained by the B-57B type airplane,"* Lo Using every opportunity to drive home the need for the B-57D, Colonel Thomas R, Waddleton of Headquarters, Air Research and Development Command, wrote to the Deputy Chief of Staff, Development, Air Force headquarters, "Their requirements still exist, and can most economically and efficiently be met by B-S7D aircraft, . . the requirements for the assignment of B-57D aircraft for AFSWO sampling is reaffirmed. Request priority action by “the B-S7D promised capabilities of as much as 8,000 feet additional altitude over that attainable by the B-57B, 252 SWEH-2-0034, 4 ( APwigHO . } wyte