<div class="htmlview paragraph">Government agencies and industries are presently in search of new approaches to lightweight, high-strength solid rocket motor cases. Republic Aviation Corporation has been investigating the suitability of high-strength steel bonded cases based on metal design allowables up to 350,000 psi. To accomplish this end, various structural adhesives were evaluated, process techniques were developed, and motor case scale models were built and tested.</div> <div class="htmlview paragraph">Tests have shown that conventional adhesives can function in a solid rocket motor case in which the metal adherent is stressed to 250,000 psi. To improve this value even further, the adhesive should be designed so that its shear modulus varies along the bonded joint. A varying shear modulus adhesive was prepared and tested on a 6-in. overlap and compared to a constant shear modulus adhesive. The former showed, at failure, a 25% higher load carrying capability under similar conditions of test.</div>