Avionics

Abstract: Reliability analysis of fault-tolerant computer systems for critical applications is complicated by several factors. Systems designed to achieve high levels of reliability frequently employ high levels of redundancy, dynamic redundancy management, and complex fault and error recovery techniques. This paper describes dynamic fault-tree modeling techniques for handling these difficulties. Three advanced fault-tolerant computer systems are described: a fault-tolerant parallel processor, a mission avionics system, and a fault-tolerant hypercube. Fault-tree models for their analysis are presented. HARP (Hybrid Automated Reliability Predictor) is a software package developed at Duke University and NASA Langley Research Center that can solve those fault-tree models. >

Abstract: This volume offers the avionic systems engineer a fundamental exposition of the mechanization and error analysis of inertial navigation systems. While the material is applicable to spacecraft and undersea navigation, emphasis is placed upon terrestrial applications on or slightly above the earth's surface. As a result, practical considerations are geared toward those aircraft navigation systems of particular current interest. Extensive use is made of perturbation techniques to develop linearized system equations, whose solutions closely approximate those obtained by nonlinear differential equations. A unified error analysis technique is developed that is applicable to virtually all system configurations. The technique provides a greatly simplified method for comparing the performance of competing system configurations.

Abstract: The occurrence of single-event upset (SEU) in aircraft electronics has evolved from a series of interesting anecdotal incidents to accepted fact. A study completed in 1992 demonstrated that SEUs are real, that the measured in-flight rates correlate with the atmospheric neutron flux, and that the rates can be calculated using laboratory SEU data. Once avionics SEU was shown to be an actual effect, it had to be dealt with in avionics designs. The major concern is in random access memories (RAMs), both static (SRAMs) and dynamic (DRAMs), because these microelectronic devices contain the largest number of bits, but other parts, such as microprocessors, are also potentially susceptible to upset. In addition, other single-event effects (SEEs), specifically latch-up and burnout, can also be induced by atmospheric neutrons.

Abstract: Sustainability in the aviation industry calls for aircraft that are significantly quieter and more fuel efficient than today's fleet. Achieving this will require revolutionary new concepts, in particular, electric propulsion. Superconducting machines offer the only viable path to achieve the power densities needed in airborne applications. This paper outlines the main issues involved in using superconductors for aeropropulsion. We review our investigation of the feasibility of superconducting electric propulsion, which integrate for the first time, the multiple disciplines and areas of expertise needed to design electric aircraft. It is shown that superconductivity is clearly the enabling technology for the more efficient turbo-electric aircraft of the future.