The Department of Defense, specifically the Navy, is seeking innovative proposals for the development of an adaptive bypass valve for Solid Fuel Ramjet (SFRJ) missiles as part of the SBIR program. The objective is to research, design, and prototype a state-of-the-art airflow bypass valve that can precisely control airflow between the inlet and combustor, thereby enhancing thrust control and combustion efficiency in supersonic flight. This technology is critical for advancing missile capabilities and may have dual-use applications in space exploration. The solicitation is currently in pre-release, with an open date of April 23, 2025, and a close date of May 21, 2025. Interested parties can find more information and submit proposals through the official SBIR website.

## Description

Ramjets are ideally suited for supersonic flight within the atmosphere. Among the different ramjet configurations, the Solid Fuel Ramjet (SFRJ) is the simplest and safest design with the highest density-specific impulse. However, the uncontrollability of the combustion process in the SFRJ engine is still the main challenge in this technology. Complex issues include engine unstart, fuel regression complexity, and flame extinction. This SBIR topic is soliciting innovative proposals for researching, designing, and prototyping a state-of-the-art airflow bypass valve between the inlet and the combustor in supersonic SFRJ missiles. The electromechanical valve precisely controls the airflow in the combustion system by splitting the inlet airflow into the combustor stream and the annular bypass duct stream around the combustor. Bypassing air around the fuel grain is a promising technique to regulate thrust and improve combustion efficiency. The feasibility of this technique is supported by preliminary development of this adaptive valve. The high-speed precision actuator of this valve adjusts the size of the valve opening in response to a signal from a separate control system unit which is not part of this topic. An adaptive valve would control the amount of airflow by positioning at any degree of opening from bypass ratios of zero to the maximum permissible while maintaining ramjet ignition. The modular design of the valve is highly recommended as it promotes its integration on current and future missile systems. If electrical power is required, an independent power supply is preferred. A successful proposal will address these four areas: bypass valve design, actuator design, internal airflow efficiency, and power management. This proposed research project is expected to lead to a state-of-the-art device that will advance supersonic missile technologies and defense capabilities. Current Specification: <ul><li> Mach range: 2-5</li><li> Altitude: 3-70 Kft msl </li><li> Temperature: Up to 2000 F </li><li> Pressure: Up to 400 psi</li><li> Weight: Low for missile </li><li> Power: Independent Battery (if required)</li><li> Materials: Any</li></ul>

## Objective

Research and design a state-of-the-art airflow bypass valve between the inlet and the combustor in a solid fuel ramjet missile to control the amount of airflow by positioning at any degree of opening from off to on and on to off, thus allowing the control of thrust, resulting in potential range extension.

## Phase I

Develop innovative approaches to design an adaptive bypass valve, actuator, and power supply for implementation on an SFRJ missile system. Prepare a Phase II plan.

## Phase II

Build and prototype a state-of-the art bypass valve and demonstrate its performance. Mature the transitioning technology during this interim technology maturity phase, depending on the Acquisition Program Office (PMA) requirements.

## Phase III: Dual Use Applications

Integrate the Phase II-developed bypass valve prototype on a supersonic SFRJ missile system and flight test the complete system. Transtion the integrated technology to acquisition programs.Dual uses of the developed technology may include space explorations, martian ramjets, and interstellar ramjets.

Adaptive Bypass Valve for Solid Fuel Ramjet Missile

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