Development of a Flexible Internal Element (FIE) for Aluminum Cased Ammunition
Technical research note 28 Jun 1973-30 Jun 1974
MORTON THIOKOL INC ELKTON MD ELKTON DIV
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It had been successfully demonstrated by Frankford Arsenal that a liquid Flexible Internal Element FIE injected into a case will prevent the catastrophic burn-through associated with aluminum case structural failure. The primary purpose of this study was to develop an FIE composition that could be preformed and perform at least equally to liquid FIE. This work was undertaken to establish a preformed FIE and an experimental fabrication process prior to manufacturing a quantity of 6.00 mm aluminum cases for the SAW program. For convenience, 5.56 mm cases were used before 6.00 mm cases were available. The Elkton Division of the Thiokol Corporation, Elkton, Maryland, was commissioned to conduct the study and prepare samples which were test fired and evaluated at Frankford Arsenal. A series of Flexible Internal Element FIE sealing cups were fabricated from several polysulfide formulations and test fired. Of the formulations tested, three types, identified as P10, P18, and P28, were effective in preventing erosion and flash, otherwise known as burn-through, in aluminum cased ammunition. Target properties of the sealing cup compositions were specific gravity greater than 1.04, a cost of less than .01cc, tensile strength greater than 300 psi, and elongation greater than 300 percent. The effectiveness demonstrated by samples of P10, P18, and particularly P28, has proven the feasibility of utilizing preformed polysulfide cups as a means of preventing burnthrough.
- Ammunition and Explosives