Accession Number:

ADA090356

Title:

Low Temperature X-Ray Diffraction Investigation of Embrittled Minimum Signature Chaparral Propellant

Descriptive Note:

Corporate Author:

ARMY MISSILE COMMAND REDSTONE ARSENAL AL PROPULSION DIRECTORATE

Personal Author(s):

• Alley, Bernard J.

Report Date:

1980-06-01

Pagination or Media Count:

14.0

Abstract:

The Army has been developing a minimum signature propellant motor for an improved CHAPARRAL air defense weapon system since 1975. As part of validation and qualification, the motor was subjected to a diurnal temperature cycling tests during FY78 to simulate field temperature storage conditions. The special cycling test consisted of 30 cycles of 24 hours each from 283 K 50 F to 347 k 165 F followed by 30 cycles of 24 hours each from 283 K to 219 K -65 F. Inspection of smokeless CHAPARRAL motors after 30 cold cycles revealed severe propellant grain cracking that, because of the increased burning surface, could result in catastrophic motor failure upon firing. This type of grain failure, with randomly located cracks, had not previously been found in other minimum signature propellants under development or in conventional double-base propellants used in Army tactical missiles. Because of the uniqueness and seriousness of the problem, and its potential impact on production of the CHAPARRAL minimum signature propellant motor, an intensive program was initiated jointly by the Army Propulsion Directorate and the propulsion contractor, Hercules Incorporated, to determine the cause of the grain failure and solve the problem. A number of possible failure mechanisms were proposed and investigated. The CHAPARRAL propellant involved in the grain failure is comprised of glycerol trinitrate nitroglycerine plasticizer a crosslinked binder of polyglycoladpate, nictrocellulose, and polycaprolactone a solid oxidizer and inorganic additives.

Descriptors:

• *LOW TEMPERATURE
• *X RAY DIFFRACTION
• *CYCLIC TESTS
• *DOUBLE BASE ROCKET PROPELLANTS
• *ROCKET PROPELLANT GRAINS
• FAILURE(MECHANICS)
• TNT
• SOLID PROPELLANT ROCKET ENGINES
• INORGANIC MATERIALS
• NITRATES
• SMOKELESS PROPELLANTS
• GLYCEROLS
• SOLID ROCKET PROPELLANT BINDERS
• CAPROLACTONES
• SOLID ROCKET OXIDIZERS
• STORAGE
• SURFACE TO AIR MISSILES
• ADDITIVES
• EMBRITTLEMENT
• SOLID ROCKET PROPELLANT PLASTICIZERS
• CRACKING(FRACTURING)

Subject Categories:

• Mechanics
• Solid Rocket Propellants

Distribution Statement:

APPROVED FOR PUBLIC RELEASE