Investigation of Performance Degradation of M446 Fuze Expelling Charge for 2.75-Inch Rocket with M259 WP Warhead.
ARMY ARMAMENT RESEARCH AND DEVELOPMENT COMMAND ABERDEEN PROVING GROUND MD CHEMICAL SYSTEMS LAB
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An investigative test was conducted at National Space Technology Laboratories NSTL, Mississippi, from 15 April to 27 April 1979 to provide data on the physical and chemical characteristics of the M446 expelling charge employed in the M259 WP warhead of the 2.75-inch rocket. Numerous warhead malfunctions were recorded during local and proving ground tests. These malfunctions were attributed to incomplete canister ejection from the warhead which resulted in poor smokescreen development. The tests at NSTL compared two lots of expelling charges made to the same drawing 5 years apart. New expelling charges functioned satisfactorily whereas, the old charges performed marginally to poorly. Closed-bomb tests provided convincing data that performance degradation could be expected with shelf life. The new charges developed pressure three times as fast as the old charges although peak levels were not drastically different. Because of the poor consistency of pressure development, high standard deviations resulted. Thus significant differences between the means of old charges and new charges existed at the 0.10 level of significance using the Students t-distribution for comparison of means. Test for moisture content and affinity for water were conducted. These tests showed that the charge composition, probably due to the percentage of black powder, was susceptible to water pickup while also containing an appreciable amount of moisture as received in containers specified hermetically sealed. The moisture content aided poor functioning performance. It is recommended that a new composition be developed for the expelling charge which does not degrade with time nor is susceptible to moisture.
- Guided Missile Warheads and Fuzes