A.2 LATER RESEARCH It is seen in Figures A.1 and A.2, illustrating the programing of the rocket and of the nose section, that the system is a complex one. "In the early stages of work on the rocket, prior to the field operation, it had been recognized that the chance of having 2 completely operational system ready for sampling the Hardtack clouds was small, because of the short length of time available for development and test firing. Nevertheless, it seemed possible that the remaining defects of a minor nature could be rectified in the field. The operational flights and tests already described show that significant progreas was made toward this objective. However, after the tests of 24 June, it became apparent that the cause of noge section leakage and other malfunctions could not be determined and corrected with facilities available at EPG. Further work, utilizing range and test installations in the United States, was essential to the attainment of a completely successful sampling system. Ac- cordingly, the rocket portion of Project 2.8 was terminated 27 June with the concurrence of the Chief, AFSWP, and the Division of Military Application, AEC. All unfired rounds were shipped to California. From July to December 1958, the Cooper Development Corp. tested the rockets from the EPG to investigate possible modes of entry of water into the sampling heads (Reference 69). Three nose sections identical to those flown in the final EPG rounds were subjected to environmental tests at North American Aviation Co. during July. The tests included lowtemperature cycle, vibration, and acceleration. For the low-temperature tests, the forward and aft seals were closed, and the programer and its container were removed. Thermocouples were placed on the O-rings of the forward and aft seals. The assembly was brought to room temperature (75° F), and the cold chamber was stabilized at ~65° F. The nose section was placed in the cold chamber and allowed to stand for 5 minutes. At the end of that time, the forward seal O-ring temperature was ~—10° F. The nose section was removed from the cold chamber and allowed to remain at room temperature for 4 minutes, then completely submerged in water for 1 minute and allowed to float at its normal level for 4 minutes. When the section was removed from the water and disassembled, it was found that no leakage had occurred. The nose section used for the vibration test was a complete flight-ready assembly except that the skin around the diffuser had been removed. The acceleration load was maintained at 5 g’s while the vibration frequency was varied from 3 to 2,000 cps. The dwell time at each resonant frequency was 1 minute. The vibration was applied first in the plane parallel to the longitudinal centerline of the assembly, then in the plane perpendicular to the centerline. No failures occurred. For the acceleration tests, a flight-ready nose section assembly was separated into two sections at the filter joint. Both sections were placed on a spin table in the deceleration plane, and the Toad was raised to 50 g’s and held there for 1 minute. No failures occurred. The sections were then placed in the acceleration plane, and the load was again increased to 50 g’s and maintained at that level for 1 minute. The programer started its functions at approximately 15 g’s, continued to operate properly, and nofailures occurred. The test was then repeated using the nose section that had been vibration tested, and the results were the same. The four tests showed that the sampling cone design was entirely compatible with the anticipated environmental conditions. Beginning 17 July, further testing of possible sources of leakage in the nose sections was conducted at the Morris Dam Small Caliber Range, Azusa, California, which is a 56