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Technical Paper

Thin Film Permeable Membranes for Inert Gas Generation

A new ultrathin-backed semipermeable membrane has been developed which shows considerable promise as a gas separator for engine bleed air to provide nitrogen-rich air for aircraft fuel tank inerting. The membrane is a silicone, polycarbonate copolymer of 1500 Å effective thickness, deposited on a reinforced porous backing. The selective removal of oxygen provides oxygen concentrations of less than 9% in the inerting gas. Small-scale testing demonstrated that the backed membranes are suitable in the aircraft environment. A system using such membranes avoids the logistic and service requirements of tanked liquid nitrogen.
Technical Paper

The Marine Gas Turbine for the 1990's and Beyond

This paper discusses the technology, components and systems incorporated in the design of the LM1600 I/CR marine gas turbine propulsion system as well as describing some of the novel and imaginative ways that the highly acclaimed F404 fighter aircraft engine has been modified and adapted to provide the nucleus for this sophisticated marine propulsion system. Specifically, the modifications to the compressors, the high and low pressure turbines and the power turbine design characteristics are described. The proven materials technology from the highly successful LM2500 marine gas turbine has been applied to this engine as well.
Technical Paper

Selection Factors for VTOL Powerplants

This paper presents the effect of certain powerplant characteristics which must be considered in selecting the engine for a VTOL airplane. Selection factors discussed include: power matching, disc loading, aircraft control provisions, weight trades, and transition. The interrelationship of propulsion and airplane characteristics are based on subsonic considerations with emphasis on VTOL rather than STOL. The discussion is applicable to engines for VTOL aircraft of 0.3 to 0.9 Mach number and of the fixed wing category. Powerplant selection for VTOL demands timely attention to many details not existing in conventional aircraft.
Technical Paper

SP-100 Thermoelectric Converter Technology Development

As part of the SP-100 Space Reactor Power System Program being undertaken for the U. S. Department of Energy, GE is developing a thermoelectric (T/E) power converter which utilizes reactor delivered heat and transforms it into usable electric power by purely static means. This converter is based to GE's product line of successful thermoelectric space power systems. The SP-100 power converter embodies the next generation improvement over the type of T/E converter successfully flown on the six U. S. space missions. That is, conduction coupling of T/E cell to both the heat source and the heat rejection elements. The current technology utilizes radiation coupling in these areas. The conduction coupling technique offers significant improvements in system specific power since it avoids the losses associated with parasitic ΔT's across the radiation gap between the heat source and the hot junction of the thermoelectric (T/E) cell.
Technical Paper

SP-100 Position Multiplexer and Analog Input Processor

This paper describes the design, implementation, and performance test results of an engineering model of the Position Multiplexer (MUX)-Analog Input Processor (AIP) System for the transmission and continuous measurements of Reflector Control Drive position in SP-100. The specially tailored MUX-AIP combination multiplexes the sensor signals and provides an increase in immunity from low frequency interference by translating the signals up to a higher frequency band. The modulated multiplexed signals are transmitted over a single twisted shielded cable pair from the reflector drives located near reactor to the AIP located at the power conditioning/system controller end of the space craft boom. There the signals are demultiplexed and processed by the AIP, eliminating the need for individual cables for each of the twelve position sensors across the boom.
Technical Paper

SP-100 Nuclear Subsystem Hardware and Testing

The term “SP-100” is synonymous with a set of technologies that can be utilized to provide long lifetime, reliable, safe space power over the range of kilowatts to megawatts [1] using a nuclear reactor as the heat source. This paper describes recent development progress in a number of technology areas such as fuel, materials, reactivity control mechanisms and sensors. Without exception, excellent technical progress is being accomplished in all areas under development to optimize spacecraft performance characteristics.
Technical Paper

SP-100 Early Flight Mission Designs

Early flight mission objectives can be met with a Space Reactor Power System (SRPS) using thermoelectric conversion in conjunction with fast spectrum, lithium-cooled reactors. This paper describes two system design options using thermoelectric technology to accommodate an early launch. In the first of these options, radiatively coupled Radioisotope Thermoelectric Generator (RTG) unicouples are adapted for use with a SP-100-type reactor heat source (Deane 1992). Unicouples have been widely used as the conversion technology in RTGs and have demonstrated the long-life characteristics necessary for a highly reliable SRPS (Hemler 1992). The thermoelectric leg height is optimized in conjunction with the heat rejection temperature to provide a mass optimum 6-kWe system configured for launch on a Delta II launch vehicle. The flight-demonstrated status of this conversion technology provides a high confidence that such a system can be designed, assembled, tested, and launched by 1996.
Technical Paper

New Turbofan Engines - F101 and TF34

The General Electric Company has recently been in the process of developing two new turbofan aircraft engines-the TF34 and the F101. The TF34 has been developed for the U.S. Navy's S-3A antisubmarine warfare aircraft and has been selected by Fairchild-Hiller for the U.S. Air Force A-10A; the F101 is being developed for the U.S. Air Force B-1 strategic bomber. Each of the new aircraft programs has the common requirement for subsonic endurance. The S-3A and A-10A requirements include subsonic operation only while the B-1 includes supersonic capability as well as subsonic. This basic mission-mix difference combined with major differences in engine/air vehicle installation features and different levels of technology applied due to the relative chronology in the respective development programs leads to contrasts in the design features of the major components of the engines.
Technical Paper

Initial Testing of a 250 KW Starter/Generator for Aircraft Applications

The work reported in this paper has been conducted by a team from GE-Aircraft Engines, GE-CR&D, and Sundstrand under a contract sponsored by the USAF, Wright Laboratories, WPAFB, Contract No. F33615-90-C-2052. The objective of this contract is to prove the feasibility of an Integral Starter/Generator (IS/G) through the preliminary design stage and demonstrate the starter/ generator technology in the externally mounted version utilizing switched reluctance machine technology. This paper will report on the progress for the EIS/G-system through the initial testing stage. Comparison of the finished hardware with the design results presented earlier will lead of the paper. This is followed by the discussion of the early testing results for the system testing. Recommendation on additional testing will be presented at the end of the paper.
Technical Paper

High Temperature Turbine Design Considerations

The major technological developments which have made possible the trend towards higher temperatures in modern aircraft gas turbine engines are discussed. The relative importance of manufacturing processes, material developments, cooling techniques, analytical design procedures, rupture and cyclic life considerations, and aerodynamic and mechanical design improvements are discussed along with illustrative examples and technical data. The need for a balanced design approach is stressed, and examples are given where trade-offs can be made. It is noted that the advances in aircraft engines during the last 10 years have been based on the evolution of sound engineering principles, extensive component and engine development, and careful consideration of the operational requirements rather than a tremendous breakthrough or revolutionary concept in any one area.
Technical Paper

Development of Hot-Isostatically Pressed and Forged P/M Rene 95 for Turbine Disc Application

Previous studies had demonstrated the economic and technical feasibility of producing high-quality forgings for aircraft turbine engine parts from hot-isostatically pressed (HIP) Rene 95 powder billets. The present program was aimed at developing a production practice for making HIP + forged turbine discs. The major goal was improved product fabricability and reliability with minimum cost. The program was conducted using argon atomized Rene 95 powder. Experimental studies were conducted to evaluate the effect of powder characteristics, HIP parameters, preform design, and forging conditions on forgeability, microstructure, and mechanical properties. The results of these studies were incorporated into a pilot production run in which 10 disc forgings were made and evaluated. The selected process involved the consolidation of -60 mesh powder to full density by hot-isostatic pressing at a temperature above the γ' solvus temperature.
Technical Paper

A New Reaction Control Approach for Sounding Rockets

This paper concerns a new technique designed to provide high performance reaction control systems for sounding rockets. Proportional control of differential thrust and simple adaptive control of thrust magnitude (based on the level of demanded thrust) is utilized. The control is being implemented with a combination of electronic and fluidic components for an Aerobee 150 sounding rocket payload whose goal is a pointing stability of 0.1 arc second.