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High ISP Controllable Solid Propellant

Description:

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Hypersonics; Advanced Materials

 

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

 

OBJECTIVE: Develop high-slope solid propellants with higher specific impulse (Isp) than state of the art for use with controllable solid propellant rockets.

 

DESCRIPTION: As controllable solid rocket material technologies advance, high-slope propellants with higher specific impulse can be developed to maximize the performance of thrusters.  The burn rate of propellants is an exponential function of chamber pressure.  Because the burn rate as a function of pressure is normally graphed on a log-log plot where the burn rate would be linear, propellants with high exponent values are commonly called high slope propellants.  This topic seeks new propellants or improvements to existing propellant formulations to maximize specific impulse while achieving high burn rate exponents at a wide range of pressures.  Additional factors to consider are communications interference and high melting point by-products that may solidify on motor components during operation.  For these reasons, reduced smoke propellants typically trade more favorably than smoky propellants.  Desired applications include throttling axial motors and divert and attitude control systems.

 

PHASE I: Develop a class 1.3 propellant optimized for high specific impulse, burn rate exponents greater than 0.7, and stable combustion at wide range of pressures.  Proposers may demonstrate the combustion temperature and specific impulse of the proposed propellant by analysis, but must physically demonstrate actual burn rates at multiple pressures.  Low fidelity burn rate measurements like strand burning are acceptable for Phase I.  A propellant whose combustion gas composition minimizes partial pressures of oxidizing species like oxygen and water is desired but not required.  Partnership with a propulsion system manufacturer would help significantly to guide Phase I goals for desired pressure ranges, combustion temperatures, and other values.

 

PHASE II: Determine the burn rate of the propellant developed in Phase I through small scale motor burn rate testing for the pressures tested in Phase I.  Demonstrate repeatable production of propellant or ingredients using scalable production methods.  The proposed propellant must have a shelf-life of more than 20 years as determined by aging data.  Thermal structural analysis, testing, or a combination of both must demonstrate that the proposed propellant can survive storage in temperatures as low as -40 °C.

 

PHASE III DUAL USE APPLICATIONS: Partner with a controllable solid propellant thruster manufacturer to test the propellant. Demonstrate that the burn rate of the proposed propellant is reproducible at ambient temperature with a variation less than 10% at the pressures specified by a manufacturer. During Phase III the effect of initial motor temperature on the burn rate of the propellant must be determined.

 

REFERENCES:

  1. G. P. Sutton and O. Biblarz, Rocket Propulsion Elements, New York: Wiley, 2001.
  2. A. E. Oberth, Principles of Solid Propellant Development, Fair Oaks, 1986.
  3. R. L. Lou and A. Katsakian, Fast-Burning Rate/High Slope Propellant Technology Program, AD0514877

 

KEYWORDS: propellant; controllable solid propulsion; specific impulse

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