SEcREt 2p” 0018933 cones in which a vacuum (23 inches of mercury), similar to the nearvacuum of the upper atmosphere, ‘had been induced. Examination of these assemblies after recovery showed that the vacuum remained when the - breathe hole was sealed, A total of 27 tests using 10 nose cone assemblies.were conducted over a 5-day period,. This work, plus further testing at the Cooper Development Corporation plant, indicated that certain points around the forward ball~ seal joint and the operating mechanism were susceptible to small leaks as the pressure difference between the interior and exterior of the diffuserfilter section increased, The neoprene boot, ‘which covered the operating mechanism, had proved to be particularly vulnerable during the Pacific firings and later tests, The reliability of the seal was increased a great deal by redesign of the boot, and only infrequent minute leaks were observed after installation of the improved boots. ‘These leaks were repaired as they occurred until the seal was tight enough to hold a pressure difference of 23 inches of mercury for 10 minutes, Following the successful drop tests, two flight test rounds were fired at NAMTC, Point Mugu, California, on 24 July. The nose cones for these rounds were modified to incorporate the improvements which had been made during the tests at Morris Dam, All programmer function times were 2s planned and both rounds were judged to be quite successful, Their trajec-