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Article

2050 aircraft engine designs go radical, part 1

2018-10-23
The search for ever-lower emission technology for future generations of aircraft engines is actively progressing on both sides of the Atlantic. Tucked away on a modest-size stand at this year’s Farnborough International Airshow was a highly varied collection of unconventional engine technology displays – a clear indication of radical innovation already being investigated as a part of Ultimate, the European Horizon 2020 research and innovation project.
Article

2050 aircraft engine designs go radical, part 2

2018-10-24
In part two of a two-part series, Richard Gardner discusses various aerospace propulsion innovations and continued work by aerospace engineers and scientists to advance aircraft engine technologies to increase efficiency and lower emissions.
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

A COMPARISON OF TURBINES FOR TURBOJET ENGINES AND SPACE POWERPLANTS

1963-01-01
630113
The characteristics of turbines for turbojet and space power plant applications are compared on the basis of power requirement trends, working fluids, materials, and system requirements. The differences in Brayton and Rankine cycles, the requirements of the cycles imposed on turbines, and typical losses inherent in present low power space turbines are discussed. A comparison is made of representative present and future turbines for turbojet and space power applications. Future large space turbines will parallel the performance and design techniques of high performance gas turbines. Some of the design techniques of steam turbines can also be used because of experience with wet vapor and long endurance. The future goals and problem areas of turbojet and space turbines are shown.
Technical Paper

A Comparative Study of a Multi-Gas Generator Fan to a Turbofan Engine on a Vertical Takeoff and Landing Personal Air Vehicle

2006-08-30
2006-01-2435
This paper attempts to assess the benefits of a unique distributed propulsion concept, known as the Multi-Gas Generator Fan (MGGF) system, over conventional turbofan engines on civilian vertical takeoff and landing (VTOL) applications. The MGGF-based system has shown the potential to address the fundamental technical challenge in designing a VTOL aircraft: the significant mismatch between the power requirements at lift-off/hover and cruise. Vehicle-level performance and sizing studies were implemented using the Grumman Design 698 tilt-nacelle V/STOL aircraft as a notional personal air vehicle (PAV), subjected to hypothetical single engine failure (SEF) emergency landing requirements and PAV mission requirements.
Journal Article

A Continuing Investigation of Diurnal and Location Trends in an Ice Crystal Icing Engine Event Database

2019-06-10
2019-01-1964
Due to ongoing efforts by the aviation industry, much has been learned over the last several years regarding jet engine power loss and compressor damage events caused by the ingestion of high concentrations of ice crystal particles into the core flow path. Boeing has created and maintained a database of such ice crystal icing (ICI) events to aid in analysis and further study of this phenomenon. This article provides a general update on statistics derived from the Boeing event database, and provides more details on specific event clusters of interest. A series of three flight campaigns have, over the past five years, collected in-situ data in deep convective clouds that will be used for the assessment of the new FAA CFR Part 33 ice crystal environmental envelope Appendix D, and the equivalent EASA CS-25 Appendix P.
Technical Paper

A Control Concept Combining the Best of the Current Hydromechanical and Electronic Technologies

1974-02-01
740380
The AiResearch TFE731-2 Turbofan Engine Control system was created out of a recognition of engine and aircraft operating requirements in which a free weighting of candidate control components and logic was made. From this free design iteration process, which considered both conventional and advanced concepts of control, the control described in this paper has evolved and has fulfilled the in-flight operating requirements of the engine.
Standard

A GUIDE TO AIRCRAFT TURBINE ENGINE VIBRATION MONITORING SYSTEMS

1992-03-10
HISTORICAL
AIR1839A
This Aerospace Information Report (AIR) is a general overview of typical airborne vibration monitoring (AVM) systems with an emphasis on system hardware design considerations. It describes AVM systems currently in use. The purpose of this AIR is to provide information and guidance for the selection, installation, and use of AVM systems and their elements. This AIR is not intended as a legal document but only as a technical guide.
Standard

A Guide to Aircraft Turbine Engine Vibration Monitoring Systems

2015-12-20
CURRENT
ARP1839
This Aerospace Recommended Practice (ARP) is a general overview of typical airborne engine vibration monitoring (EVM) systems applicable to fixed or rotary wing aircraft applications, with an emphasis on system design considerations. It describes EVM systems currently in use and future trends in EVM development. The broader scope of Health and Usage Monitoring Systems, (HUMS) is covered in SAE documents AS5391, AS5392, AS5393, AS5394, AS5395, AIR4174. This ARP also contains the essential elements of AS8054 which remain relevant and which have not been incorporated into Original Equipment Manufacturers (OEM) specifications.
Standard

A Guide to Aircraft Turbine Engine Vibration Monitoring Systems

2001-07-01
HISTORICAL
AIR1839B
This SAE Aerospace Information Report (AIR) is a general overview of typical airborne engine vibration monitoring (EVM) systems with an emphasis on system design considerations. It describes EVM systems currently in use and future trends in EVM development.
Standard

A Guide to Aircraft Turbine Engine Vibration Monitoring Systems

2008-02-16
HISTORICAL
AIR1839C
This Aerospace Information Report (AIR) is a general overview of typical airborne engine vibration monitoring (EVM) systems applicable to fixed or rotary wing aircraft applications, with an emphasis on system design considerations. It describes EVM systems currently in use and future trends in EVM development. The broader scope of Health and Usage Monitoring Systems, (HUMS ) is covered in SAE documents AS5391, AS5392, AS5393, AS5394, AS5395, AIR4174.
Technical Paper

A High Efficiency Fuselage Propeller (”Fusefan”) for Subsonic Aircraft

1999-10-19
1999-01-5569
This report proposes a new high efficiency “fuselage fan” concept of aircraft propulsion for subsonic airplanes also noted as “fusefan” (FF). The fusefan concept consists of one or two rings of swept blades rotating around the fuselage. This variable pitch fan has an important advantage in comparison with currently used turbofan engines: it dramatically increases the cross-sectional bypass area of the propulsion system by 3-5 times. As shown in the paper this propeller has an efficiency in cruise flight of 9-16% more than the current turbofan propulsion system. It also provides a large increase in static thrust (40-75%), which in turn decreases takeoff distance about 30-45%, and has a clean wing aerodynamically due to the absence of nacelles. An analysis of the benefits of the fuselage fan compared with the Advanced Turboprop Propeller (ATP) and propfan “Unducted Fan” (UDF) shows that for equal disk loading the “fuselage fan” has the following advantages: 1.
Technical Paper

A Look at the MIL-L-23699 (WEP) Lubricants

1965-02-01
650816
Laboratory, component, and engine tests have been conducted by the General Electric Co. to evaluate the various lubricant properties important to the J79 jet engine. Such properties as elastomer volume swell, oxidation-corrosion, coking characteristics, and lubricity were evaluated. The effects of these various properties on engine performance and how the laboratory results relate to the component results and engine test results are discussed.
Standard

A MEANS OF TESTING TURBOJET ENGINE STARTER PERFORMANCE

1963-11-01
HISTORICAL
ARP715
This Recommended Practice covers a means of determining the performance acceptability of new production or overhauled starters that will be used for cranking turbine engines and is intended for use where torque measuring equipment is not available or desirable. This method determines acceptability of the overall performance of the starter on a flywheel test stand, rather than the performance at specific speed conditions. It allows a slight variation of output torque outside specified limits, as long as the overall performance is up to standard.
Standard

A Methodology for Assessing Inlet Swirl Distortion

2010-10-25
CURRENT
AIR5686
This Aerospace Information Report (AIR) addresses the subject of aircraft inlet-swirl distortion. A structured methodology for characterizing steady-state swirl distortion in terms of swirl descriptors and for correlating the swirl descriptors with loss in stability pressure ratio is presented. The methodology is to be considered in conjunction with other SAE inlet distortion methodologies. In particular, the combined effects of swirl and total-pressure distortion on stability margin are considered. However, dynamic swirl, i.e., time-variant swirl, is not considered. The implementation of the swirl assessment methodology is shown through both computational and experimental examples. Different types of swirl distortion encountered in various engine installations and operations are described, and case studies which highlight the impact of swirl on engine stability are provided. Supplemental material is included in the appendices.
Technical Paper

A Model for Time Varying and Interfering Stress-Strength Probability Density Distributions with Consideration for Failure Incidence and Property Degradation

1964-01-01
640616
The Reliability prediction approaches which are commonly used to estimate the Reliability of complex electronic devices are shown not to apply to the structural elements of the highly stressed parts of such mechanical devices as turbojet engines. The paper introduces the fundamental relationships of computing the probability of failure from interfering and compatible stress-strength probability functions as the most promising approach to the Reliability analysis of structural elements. The changes of the probability density functions with time as a result of failure incidence probability and strength degradation are analyzed and described. The effect of these changes on the probability of failure in the sense of a force of mortality function are introduced and a digital computer approach to the solution of the analytical complexities is described. Preliminary results from this computerized approach to structural Reliability analysis are given.
Technical Paper

A New High Bypass Fan for General Aviation

1980-04-01
800602
A small, high bypass turbofan engine, suitable for use in general aviation aircraft, was designed, built and tested. Key features of the engine include low noise, low exhaust emissions and high propulsive efficiency. Testing was conducted with a simulated flight nacelle. Exhaust emissions were measured and the noise data taken was used to predict sideline, takeoff and approach noise levels.
Technical Paper

A New Maintenance Tool For Aircraft

1962-01-01
620445
The application to aircraft power plants of a well proven laboratory control program previously applied to terrestrial bound power plants will be discussed. The program incorporates physical tests and spectrometric analyses of lubricants and a new technique using spectrometric analyses of jet turbine engine exhaust deposits. Examples of the successful application of the program by the maintenance forces concerned with reciprocating engines and jet engines will be given.
Technical Paper

A Novel and Simple Model for Preliminary Aircraft Parameters Selection Using Turbofan Engine Database

2004-11-16
2004-01-3399
Aircraft engine selection is an important part of both the design process of a new aircraft and the re-powering of an existing aircraft. This paper is a step further on Svoboda's [1] turbofan engine database as a preliminary design tool, aiming at a novel and simple tool for turbofan engine selection during the preliminary aircraft parameters definition, as well as at evaluating current configurations and identifying future trends for the turbofan engines.
Technical Paper

A Probabilistic Evaluation of Turbofan Engine Cycle Parameters for a Mach 1.8 Interceptor Aircraft

2003-09-08
2003-01-3056
A supersonic engine for a high Mach interceptor mission is modeled, and the requirements for the engine at different flight conditions are discussed. These include low fuel consumption at a non-afterburning supersonic dash Mach number for interception, and high thrust, both afterburning and non-afterburning, at a high subsonic Mach number for combat engagement. In addition, the engine should have low frontal area and low weight for a given sea level thrust rating. For the design point, the sea level static, standard day non-afterburning thrust is fixed at 20,000 lbs. The primary independent parameters varied in the study are fan pressure ratio, overall pressure ratio, turbine inlet temperature, throttle ratio, and extraction ratio. A design of experiments (DoE) is set up to vary the independent parameters to produce a meta-model for engine performance, geometry and weight.
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