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Technical Paper

21st Century Aircraft Potable Water Systems

1999-10-19
1999-01-5556
Aircraft potable (drinking) water systems haven’t changed significantly in the last half-century. These systems consist of cylindrical water tanks pressurized by bleed air from the jet engines, with insulated stainless steel distribution lines. What has changed recently is the increase in the possibility of aircraft picking up contaminated drinking water at foreign and domestic stops. Customer awareness of these problems has also changed - to the point where having reliable drinking water is now a competitive issue among airlines. Old style potable water systems that are used on modern aircraft are high maintenance and exacerbate the growth of microbes because the water is static much of the time. The integrity of some pressurized water tanks are also a concern after years of use. Cost-effective mechanical and biological solutions exist that can significantly reduce the amount of chemicals added and provide good potable water.
Technical Paper

4000 F Oxidation Resistant Thermal Protection Materials

1966-02-01
660659
Coated refractory metals, coated and alloyed graphites, hafnium-tantalum alloys, refractory borides, and stabilized zirconias are considered for the 3600–4000 F high-velocity air environment. Only refractory borides and stabilized zirconias are indicated as offering long duration and reuse capabilities for such high-temperature utilization. Iridium, as coatings on substrates of either graphites or refractory metals, appears attractive for shorter times (less than 1 hr). Environmental evaluation and the need for a theoretical framework to enable the prediction of performance data for such materials are indicated to be major problems facing users and suppliers.
Technical Paper

4000–5000 R Temperature Surveys in Mach 0.2–0.6 Hydrocarbon Hot Gas Streams

1963-01-01
630367
This paper discusses five different methods for measuring the gas stream temperature from a burner using a hydrocarbon fuel, air, and oxygen. Tests were made with a single shielded BeO probe, a bare wire iridium -- 60% rhodium/iridium couple, a tantalum triple shielded platinum -- 10% rhodium/platinum thermocouple, the sodium line reversed technique, and a watercooled total enthalpy probe. The most serviceable system proved to be the bare wire iridium -- 60% rhodium/iridium couple, particularly for carrying out stream surveys where relative, rather than true temperatures, are of primary concern. More study is needed to establish a system for determining the true stream temperature.
Technical Paper

50 to 100-Ah Lithium Ion Cells for Aircraft and Spacecraft Applications

1997-06-18
971230
As a part of a program jointly supported by the USAF and Canada's Department of National Defense, BlueStar is developing large (50 to 100-Ah)lithium ion cells for aircraft and spacecraft applications. Presently, 20-Ah cells are being developed as the first stage of the scale-up process and the design of these cells involves several tradeoffs related to the specific nature of this application. This paper will present the design of this first generation cell in the context of these tradeoffs as well as presenting the results of the performance and life testing of these cells.
Standard

8000 psi Hydraulic Systems: Experience and Test Results

1994-09-01
HISTORICAL
AIR4002
Shortly after World War II, as aircraft became more sophisticated and power-assist, flight-control functions became a requirement, hydraulic system operating pressures rose from the 1000 psi level to the 3000 psi level found on most aircraft today. Since then, 4000 psi systems have been developed for the U.S. Air Force XB-70 and B-1 bombers and a number of European aircraft including the tornado multirole combat aircraft and the Concorde supersonic transport. The V-22 Osprey incorporates a 5000 psi hydraulic system. The power levels of military aircraft hydraulic systems have continued to rise. This is primarily due to higher aerodynamic loading, combined with the increased hydraulic functions and operations of each new aircraft. At the same time, aircraft structures and wings have been getting smaller and thinner as mission requirements expand. Thus, internal physical space available for plumbing and components continues to decrease.
Standard

8000 psi Hydraulic Systems: Experience and Test Results

2012-11-15
CURRENT
AIR4002A
Shortly after World War II, as aircraft became more sophisticated and power-assist, flight-control functions became a requirement, hydraulic system operating pressures rose from the 1000 psi level to the 3000 psi level found on most aircraft today. Since then, 4000 psi systems have been developed for the U.S. Air Force XB-70 and B-1 bombers and a number of European aircraft including the tornado multirole combat aircraft and the Concorde supersonic transport. The V-22 Osprey incorporates a 5000 psi hydraulic system. The power levels of military aircraft hydraulic systems have continued to rise. This is primarily due to higher aerodynamic loading, combined with the increased hydraulic functions and operations of each new aircraft. At the same time, aircraft structures and wings have been getting smaller and thinner as mission requirements expand. Thus, internal physical space available for plumbing and components continues to decrease.
Technical Paper

90 Ah Dependent Pressure Vessel (DPV) Nickel Hydrogen Battery Qualification Test Results

1999-08-02
1999-01-2590
In 1995, the Naval Research Laboratory (NRL) began a program to investigate whether a 90 Ah dependent pressure vessel (DPV) NiH2 battery pack could be a lower volume replacement for a 90 Ah NiH2 IPV spacecraft battery. Nickel Hydrogen (NiH2) dependent pressure vessel (DPV) battery cells are presumed to offer all the features of the NiH2 IPV battery cell with considerably less volume. To achieve this reduction in volume, the DPV cell utilizes a canteen shaped pressure vessel with reduced thickness wall, flat sides and curved ends. The cells can be packaged similar to prismatic nickel cadmium battery cells. Moreover, like NiCd cells, a fully charged DPV cell must rely upon an adjacent battery cell or structure for support and to maintain pressure vessel integrity. Seventeen 90 Ah NiH2 DPV cells were delivered to NR in 1998 for qualification tests. An eleven-cell half battery pack was manufactured and tested to validate the advantages of the DPV design.
Technical Paper

A Compact High Intensity Cooler (CHIC)

1983-07-11
831127
A unique heat exchanger has been developed with potential applications for cooling high power density electronics and perhaps high energy laser mirrors. The device was designed to absorb heat fluxes of approximately 50 w/cm2 (158,000 Btu/hr.ft2) with a low thermal resistance, a high surface temperature uniformity and very low hydraulic pumping power. A stack of thin copper orifice plates and spacers was bonded together and arranged to provide liquid jet impingement heat transfer on successive plates. This configuration resulted in effective heat transfer coefficients, based on the prime surface, of about 85,000 w/m2 °C (15,000 Btu/hr.ft2 °F) and 1.8 watts (.002 HP) hydraulic power with liquid Freon 11 as coolant.
Technical Paper

A Comparison of Fatigue Test Techniques for Gas Turbine Oils - (Report of the CRC-Aviation Bearing Fatigue Panel of the Group on Gas Turbine Lubrication)

1968-02-01
680322
A number of specimen life performance tests were conducted on three test lubricants selected to demonstrate their gross ranking capabilities. The results indicated that the test rigs should be used only for gross ranking. A large difference in magnitude of life values were obtained even though agreement in gross ranking was obtained by three out of the five participating laboratories. Further testing is recommended under preselected test conditions and lubricants.
Technical Paper

A Comparison of Numerical Techniques for the Study of Lightning Indirect Effects

2001-09-11
2001-01-2894
A comparison of various numerical tools and techniques was performed for calculating the lightning indirect effects to composite structures and internal systems. This paper is a summary of the initial comparison results. Detailed results of each technique considered are given in additional separate papers presented during this conference. The modeling considered current distributions over and within composite surfaces and the coupling of current and voltages to internal systems such as wire bundle cables and hydraulic and fuel tubes. The models were compared to each other and to measured data from low level swept continuous wave (LLCW) tests performed on two test fixtures. Other features of the codes such as run time, ease of use, computer requirements, availability of documentation and technical support, etc. are compared as well.
Technical Paper

A Comparison of Root Module Designs Relative to Wheat Growth and Development: Defining the Requirements for a Space Based Plant Culture System

2000-07-10
2000-01-2508
Wheat plants were grown at water potentials in the root zone of -0.4, -3.0, and -5.0 kPa in root modules with various porous membranes through which the nutrient solution was delivered. Root modules contained plants grown during 49 days on different types of porous membranes: ceramic porous tubes with diameters of 10 mm or 22 mm, a porous titanium plate, in a compartment with a porous ceramic tube in perlite and in a 2.5 cm layer of perlite which covered a porous titanium plate. Root modules containing perlite showed much higher dry mass plants in yield than plants in root modules without perlite. A drop in water potential resulted in growth inhibition in all of the modules, especially in the tests without perlite. Design characteristics of the modules significantly affected the root distribution volume. These results may provide additional information in the design of root modules for future space plant growth chambers.
Technical Paper

A Comparison of the Prediction of Lightning Indirect Effects Using 2-D Analytical Tools with Measured Data from Two Composite Test Fixtures

2001-09-11
2001-01-2904
A comparison was done of the prediction capabilities for lightning indirect effects of two two-dimensional (2-D) computer codes using two graphite structural test fixtures. The two codes evaluated were an internal Boeing Method-of-Moments code and a commercially available Boundary Element method code. The codes were compared against each other and against test data. The purpose was to evaluate the prediction capabilities of both codes for use in predicting lightning indirect effects on internal components of graphite structure. Since 2-D codes are much easier to use than 3-D codes, they could be widely used in trade studies and design evaluations for lightning indirect effects protection of composite aircraft. The first code, REDIST, is a Method-of-Moments code developed in the 1980’s for use on the B-2. The REDIST code has short run times and is somewhat easier to use than the second code that was investigated.
Technical Paper

A Comparison of the Technical Properties of Arc Sprayed Versus Plasma Sprayed Nickel-5 Aluminum

1992-04-01
920931
Nickel-5 Aluminum (95 % Nickel-5 % Aluminum) is widely used in the aircraft engine industry. The excellent adhesive and cohesive strength of the coating, oxidation resistance and machinability make it an ideal material as both a bond coat for subsequent topcoats and as a build up material for dimensional restoration of worn or mismachined components. Plasma spraying has traditionally been the thermal spray process used to apply nickel aluminum, and the technical properties and performance characteristics are well documented. More recently, wire arc sprayed nickel aluminum is becoming widely used as an alternative to plasma spraying due to higher bond strengths, reproducibility, better machinability and more favorable economics. This paper presents the results of a testing program designed to compare the technical properties of arc sprayed versus plasma sprayed Nickel-5 Aluminum coatings.
Technical Paper

A Cooling System for the EAPU Shuttle Upgrade

2001-07-09
2001-01-2152
The Shuttle orbiter currently uses hydrazine-powered APU’s for powering its hydraulic system pumps. To enhance vehicle safety and reliability, NASA is pursuing an APU upgrade where the hydrazine-powered turbine is replaced by an electric motor pump and battery power supply. This EAPU (Electric APU) upgrade presents several thermal control challenges, most notably the new requirement for moderate temperature control of high-power electronics at 132 °F (55.6 °C). This paper describes how the existing Water Spray Boiler (WSB), which currently cools the hydraulic fluid and APU lubrication oil, is being modified to provide EAPU thermal management.
Technical Paper

A Corrosion Inhibiting Coating for Structural Airframe Fasteners

1973-02-01
730902
Corrosion problems associated with using titanium fasteners to assemble aluminum airframe structures are reviewed. Data are presented describing the effectiveness of metallic platings and an aluminum filled organic based coating on fasteners to render the titanium-aluminum electrochemical couple inoperative. The aluminum enriched organic coating known as Hi-Kote 1 is shown to be more effective in minimizing corrosive attack on aluminum airframe structure in both saline and acidic environments. The effectiveness of Hi-Kote 1 in corrosion-fatigue tests of fastened aluminum structure is also reported.
Journal Article

A Coupled Eulerian Lagrangian Finite Element Model of Drilling Titanium and Aluminium Alloys

2016-09-27
2016-01-2126
Despite the increasing use of carbon fibre reinforced plastic (CFRP) composites, titanium and aluminium alloys still constitute a significant proportion of modern civil aircraft structures, which are primarily assembled via mechanical joining techniques. Drilling of fastening holes is therefore a critical operation, which has to meet stringent geometric tolerance and integrity criteria. The paper details the development of a three-dimensional (3D) finite element (FE) model for drilling aerospace grade aluminium (AA7010-T7451 and AA2024-T351) and titanium (Ti-6Al-4V) alloys. The FE simulation employed a Coupled Eulerian Lagrangian (CEL) technique. The cutting tool was modelled according to a Lagrangian formulation in which the mesh follows the material displacement while the workpiece was represented by a non-translating and material deformation independent Eulerian mesh.
Technical Paper

A DISCUSSION OF SOME RECENT DEVELOPMENTS IN AIRCRAFT ENGINE OIL FILTRATION

1957-01-01
570233
An important current engineering problem in the aviation field involves the providing of increasingly effective lubricating oil filtration for today's more advanced aircraft engines. The critical demands of the higher powered reciprocating engines and the new gas turbine engines, together with the strong desire to reduce aircraft operating and maintenance costs require considerable refinement and improvement in oil filtration methods. This paper discusses some recent developments in scavenge oil filtration and describes a basic, new filter design.
Technical Paper

A Fastener Analysis Addressing Various Types of Misfit and Its Damage Life Calculations

2013-09-17
2013-01-2312
In a fastening system when there is a small misalignment of the holes, the holes are enlarged to align the axes and a next size fastener is used to fit the joint. But when the misalignment is large then the enlargement need to be proportionally large. In this case a bushing is press fit onto the hole to handle the fastening. If we press fit a bushing, it generates residual stresses in the panel. These residual stresses reduce the damage life of the components on which the bushings were press fit. In the aircraft engine nacelle components the damage life is very critical in various failure conditions such as fan blade out condition, wind milling and bird strike. It increases the flight time in these events. Here four different case studies were considered to study the damage life of the aircraft components made of Aluminum or composite material.
Technical Paper

A Feed-Back Thermal Regulation System for the Columbus Free Flyer Battery Section

1991-07-01
911409
The BSTCA (Battery Section Thermal Control Assembly) is a module of the Columbus MTFF (Man Tended Free Flyer). Electrical power required during eclipse periods, is made available from six nickel hydrogen batteries. A sophisticated multi-radiator configuration, with a hybrid heat pipe network, has evolved. Autonomous control of the assembly heat rejection capability has been achieved by a integrated network of LTHP's (Liquid Trap Heat Pipes) and CCHP's (Constant Conductance Heat Pipes) under the control of a conventional HCU (Heater Control Unit). The process of design selection and verification is discussed, for the BSTCA, with a detailed LTHP component presentation.
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