Safe and Flexible Propulsion Technologies for Kinetic Energy Boost Phase Intercept Applications
Summary:
Combustion Propulsion & Ballistic Technology Corporation (CPBT; State College, PA) is developing a gel-based bi-propellant rocket propulsion system that enables greater safety, controllability, and energy management. CPBT was funded by MDA with an SBIR Phase I contract to develop a propulsion system that can be used in the kinetic energy (KE) interceptor and divert and attitude control system (DACS).
Technology Description:
CPBT's bi-propellant system consists of a fuel-rich gel propellant and an oxidizer-rich liquid propellant, which mix on command and are ignited by a pyrogen discharge jet. The company is making the system safer by storing the propellants separately; they are thus not as volatile as current solid propellants, which contain premixed fuel and oxidizer ingredients. Reactant materials stored individually are more stable and less likely to ignite by accident.
CPBT's system enables energy management-control of the flow rate and energy release rate of the propellants as they enter the rocket engine to burn. The gelled fuel is atomized-changed from continuous liquid-like phase to discrete droplet phase-making it easier to burn. Energy management involves using real-time digital controllers to throttle the flow and energy release rates of the propellant. The reservoir tanks are pressurized to force the propellants through valve openings. The system can also adjust how much of each propellant is used by controlling the feed pressures. In contrast, a solid propellant system, being premixed, has a burn rate that cannot be effectively controlled, unless the combustor chamber pressure is altered.
The nature of CPBT's system also enables the use of more environmentally friendly propellant materials. For example, hydrogen peroxide (H2O2), which contains the same elements as water-hydrogen and oxygen-and creates steam when burned, is also being used as a potent oxidizer. Solid propellants cannot use liquid oxidizers of any kind (including hydrogen peroxide) because the oxidizing material must bind to the solid fuel; more toxic, crystalline oxidizers are used instead. Solid propellant materials, ammonium perchlorate (AP) for example, are crystalline particles that function as oxidizers and contain chlorine. When burned with fuel-rich components, like hydrocarbon fuel, ammonium perchlorate can generate hydrogen chloride leading to acid rain. The propellants to be selected in CPBT's system can be tailored to operate within the temperature range of the military's interest between -60 and 70ºC.
CPBT is also adding metallized, nano-sized powders of boron or aluminum to the fuel-rich propellant. The powders generate a substantial amount of heat when they oxidize, in turn heating the propellant products to high temperatures. Metallized powders have four functions. First, the powders' high heat of oxidation raises the flame temperature, therefore increasing the propulsive energy of the propellant. Second, the powders increase the density of the propellant which makes the density impulse higher. Third, the nanopowders enable the propellant to become a gel, making it less likely to spill. Finally, the nanopowders increase the safety of the rocket by dampening instabilities in its combustion performance. This is possible because the products of metal combustion form condensed phase particles that absorb pressure fluctuations in the combustor.
MDA Origins:
CPBT was awarded an MDA SBIR Phase I contract to develop the gel-based bi-propellant propulsion system. MDA is interested in the technology for its divert and attitude control system and its kinetic energy interceptor. MDA is interested in high Isp propellants and energy management capability. Energy management uses a sensor-feedback computer controller to regulate the flow and energy release rates of the propellant, which in turn controls the thrust profile of the missile. The flow rate can be adjusted to control the fuel-to-oxidizer ratio. If inertia will keep the missile on course, the propellant can be shut off until needed again, allowing an extended range of flight. When necessary, the flow rate also can be increased to accelerate or change the orientation or course of the missile.
Spinoff Applications:
Many companies will be interested in using high-performance bi-propellants for various commercial applications such as next-generation payload insertion, on-orbit propulsion system for satellites, underwater propulsion systems, or a gas generator for an aerospace onboard power system. CPBT has discussed next-generation space payload insertion and on-orbit propulsion systems for satellites with several large commercial companies.
Commercialization:
CPBT has a subcontract with Pennsylvania State University for performing bi-propellant combustion and propulsion characterization studies at Penn State's High Pressure Combustion Laboratory. CPBT is planning to design and develop a large-scale rocket engine, in conjunction with several commercial companies, for potential MDA's interceptor application. Furthermore, CPBT has also been invited to write a proposal for a Phase II SBIR program from MDA, which will be used to finish the testing and development of the bi-propellant system with demonstrations of controllable thrust profile.
Once the system is developed, CPBT plans to distribute it through licensing agreements and services. CPBT will assist companies with deciding which propellant materials will meet their needs and developing the system specific to their particular application.
Company Profile:
CPBT specializes in propulsion technologies and development of new propellants with high propulsive performance. Additional projects include studying the effects of nano-size particles on the burn rate of solid propellants and designing hybrid rocket motors that use gaseous or liquid oxidizers to burn with solid fuels. CPBT recently finished the formulation of several solid fuels that offer significantly higher combustion rates and specific impulses than conventional hydroxyl-terminated polybutadiene fuels.
Contact Information:
Dr. Kenneth K. Kuo
Combustion Propulsion & Ballistic Technology Corporation
1217 Smithfield Street
State College, PA 16801
Tel:(834) 238-6989
Fax:(834) 238-4189
email: CPBT@mindspring.com
Web Site:
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