The Department of Defense (DOD) is seeking proposals for the topic of "High ISP Controllable Solid Propellant" as part of their Small Business Technology Transfer (STTR) Phase I program. The research topic falls under the Missile Defense Agency branch. The objective of this solicitation is to develop high-slope solid propellants with higher specific impulse (Isp) than current state-of-the-art propellants for use with controllable solid propellant rockets. The burn rate of propellants is an exponential function of chamber pressure, and propellants with high exponent values are commonly called high slope propellants. The desired propellants should maximize specific impulse while achieving high burn rate exponents at a wide range of pressures. Reduced smoke propellants are preferred over smoky propellants due to factors such as communications interference and high melting point by-products. The applications for this technology include throttling axial motors and divert and attitude control systems.

In Phase I, proposers are required to develop a class 1.3 propellant optimized for high specific impulse, burn rate exponents greater than 0.7, and stable combustion at a wide range of pressures. Physical demonstration of actual burn rates at multiple pressures is necessary, and low fidelity burn rate measurements like strand burning are acceptable. Phase II involves determining the burn rate of the propellant through small scale motor burn rate testing and demonstrating repeatable production using scalable methods. The proposed propellant must have a shelf-life of more than 20 years and be able to survive storage in temperatures as low as -40 °C.

In Phase III, the selected proposer will partner with a controllable solid propellant thruster manufacturer to test the propellant. The burn rate of the propellant must be reproducible at ambient temperature with a variation of less than 10% at specified pressures. Additionally, the effect of initial motor temperature on the burn rate must be determined. The project duration and funding specifics are not provided in the document. For more information and to submit proposals, interested parties can visit the DOD STTR website.