engines were down rated by ABMA from 150,000 pounds to 135,000 pounds because the turbopump was not satisfactory. NAA was already in the process of modifying this unit, and two pumps were subjected to prolonged tests with satisfactory results. However, because of the critical supply of these engines, the first JUPITER missiles had to fly with the lower thrust units. In fact, while procuring the first four flyable units, the situation was far from being satisfactory to ABMA. For one thing, procurement had to be effected through WDD, which caused an undue administrative workload. Then, the uncovering of the technical design deficiencies created a severe problem in assuring the timely delivery of spare parts and modification kits. One problem had, in turn, created another. NAA was supposed to have been able to ship the missiles completely modified to ABMA in January 1957, but it was several months after that. Engine modifications of late 1956 and 1957, however, appeared to be quite successful. This was aptly demonstrated in one instance during a static test at NAA, when a unintended overrun to 195,000 pounds of thrust happened. The turbopump and the thrust chamber did not show any damage 77 . From time to time, however, technical problems, including the turbopump, did crop up. Another major propulsion system problem concerned propellant sloshing. This condition was uncovered during the firing of JUPITER IB, the second JUPITER missile fired. After a normal liftoff and up to 70 seconds, the flight program was normal, but then oscillations in pitch and yaw began to build up and the missile disintegrated at 93 seconds. Heavy instrumentation immediately located the difficulty, and data showed _____________________________

(77) Ibid.; JUP Prog Rept for Apr 57, undated; JUP Prog Rpt for Aug 57, 6 Sep 57, Hist Off files.