December a series of the engine tests has been made to determine the operations and P-V power characteristics of the NALSEM-125 engine when varying pressures and temperatures of the working fluid. Some significant findings from an analysis of the early engine data are summarized below. 1. A transfer port of working gas between expansion and compression spaces may be an important factor to the gamma-type free piston design. Magnetic action of the linear alternator on the piston motion must also be considered in the dynamic design. 2. The NALSEM engine indicates the same tendency in thermodynamic performance as the conventional kinematic Stirling engines with a crank drive mechanism. Additionally more detailed engine analysis and modifications are required to optimize the thermodynamically and dynamically coupled operation. 3. The present test data may be useful to design a simple numerical code with both models of Schmidt cycle and forced dynamic oscillation for prediction of the engine performance. (Paper number IAF-ICOSP89-4-4.) 4-6. Solar Dynamic Power Supporting Development Activities for Space Station Freedom: An Overview and Accomplishments Daniel E. Sokolowski NASA Lewis Research Center, 21000 Brookpark Road, Cleveland, OH44135, USA. The Electrical Power System (EPS) for Space Station Freedom will initially consist of photovoltaic power modules up to a currently planned level of 75 kW. Beyond this level, solar dynamic power modules in units of 25 kW will be installed until a planned level of 325 kW is realized. While the EPS primary contractor is designing, developing, and testing hardware that will lead to the flight configuration, NASA Lewis Research Center (LeRC) continues to conduct and manage development activities both in-house and through contracts and grants. These activities support the prime contractors' and associated subcontractors' development of the solar dynamic power system components. These include a solar energy concentrator, receiver, power conversion unit, and heat radiator. This paper provides a brief history of the NASA LeRC solar dynamic power supporting development activities that began in 1984, an overview and important accomplishments to date of the major component hardware being developed, a discussion of the integration of the supporting development hardware with the prime contractor's activities, and a look at plans to meet future challenges. (Paper number IAF-ICOSP89-4-6.) 4-7. Preliminary Design and Testing of the Space Station Solar Dynamic Radiator for LEO Micrometeoroid and Debris Environment M. L. Fleming & R. W. Melin LTV Missiles and Electronics Group, Missiles Division, Dallas, Texas, USA. LTV is currently designing a single phase, pumped liquid Solar Dynamic Radiator for the Space Station Electrical Power System. Included in the system specification is a 0.95 probability requirement for the radiator to survive low earth orbit micrometeoroid and debris environment for ten years. The current design of the two redundant fluid paths in the radiator is provided protection by either structure or facesheets to break up particles when impacted. Two different penetration equations, in conjunction with the SP-8042 micrometeoroid environment and the JSC-2001 debris environment, are used to calculate the vulernability of each system component. Combining these component reliabilities yields the overall system reliability. This paper discusses the current status of the effort to apply the micrometeoroid and debris
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