Use of Heat Input to Infer Wear in the M188E2 Propelling Charge
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
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Gun barrel wear technology advanced during the past decade with the advent of wear sensors or imbedded thermocouples to estimate wear of large caliber guns by firing a small number of rounds in contrast to standard wear tests in which many rounds are expended. The wear screening techniques have been chiefly applied to unraveling the mysteries of additives. The Test and Evaluation Command TECOM and the Army Materiel Systems Agency AMSAA proposed using thermocouples and a wear test simultaneously in the M188E2 product improvement program. Pullover measurements and heat input measurements disagreed. This seemed surprising in view of the past experience with the thermal sensors in the 155-MM XM201E2 program. It was decided to review the 8- inch M188E2 wear test relying on stargauge measurements rather than the less accurate pullover measurements. This report describes the thermal techniques, their use in the design of the 155-mm XM201 series of charges, and the results of the heat inputs and wear measurements in the 8-inch M188E2 product improvement program. The conclusions reached were as follows a. Pullover and stargauge measurements made during the M188E2 wear testing differ by 0.08 mm to 0.23 mm 3 mils to 9 mils. b. The stargauge measurements suggest that the M188E2 wear test cannot distinguish whether the Zone 9 charge is more erosive than the Zone 8 charge. c. The 500 round wear test for the M188E2 charge sheds no more light on the relative wear between the M188E1 and M188E2 charges than the heat input tests. It is incorrect to view the 188E2 test as evidence for the failure of the thermal sensing technique to assess relative erosivity between propelling charges.
- Ammunition and Explosives