Thiokol Corporation

Cordant Technologies Inc.

Ronald W Nelson

Larry W Poulter

Robert B Smalley, Jr

Marvin C Hawkins

Merylin B Lovett

Elizabeth K Bonderson

The present invention concerns an erosion resistant, low signature liner for solid propellant rocket motors and rocket motors having such a low signature liner. The liner combustion products in the exhaust plume have low visibility in the IR and visible light spectra which is essential for use in low signature solid propellant rocket motors. The liner also forms an in-situ protective layer at elevated temperatures for enhanced erosion resistance. These erosion resistant properties eliminate the need for supplemental case insulation which would contribute additional smoke and combustion products to the exhaust plume as well as add additional costs and inert weight to the motor.

Erosion resistant-low signature liner for solid propellant rocket motors

A robust polyurethane liner is disclosed for solid propellant rocket motors which is insensitive to large variations in stoichiometry, exhibits increased cohesive strength and, when used in combination with a unique two coat (wet coat) liner process described below, modifies the ballistic properties of the adjacent interfacial propellant layer. The liner compositions include a polymeric binder having a plurality of reactive hydroxyl functional groups and a curing agent having a plurality of reactive isocyanate functional groups. The quantity of binder and curing agent is selected such that the NCO/OH ratio is in the range from 1.5 to 4.5. Diisocyanate curing agents are particularly useful. A bonding agent, such as a polyfunctional aziridine compound, is typically present in the liner composition in an amount ranging from about 3% to about 5%, by weight. An oligomer catalyst is included in the liner composition in an amount ranging from about 15% to about 50%, by weight. Diammonium phosphate ((NH.sub.4).sub.2 HPO.sub.4) functions as an oligomer catalyst and as a ballistic modifier to inhibit propellant burn rate when the liner is cured concurrently with the propellant. A colorant, such as rhodamine B, may optionally be included to assist in determining coverage or thickness of the liner coating.

Robust propellant liner and interfacial propellant burn rate control

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Brigham City, UT, United States of America

Ronald W Nelson