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Viewing 70801 to 70830 of 108026
1990-09-01
Technical Paper
901986
Alain Fourrier, Jean-Alain Jouan
HUREL-DUBOIS patented a new concept of thrust reverser in 1981 known as “the door forward reverser”. It gives numerous advantages over the conventional cascade reverser, and in particular is inherently lighter. The extensive use of advanced materials has allowed a highly competitive weight to be achieved. This paper describes the work currently under way for the pivoting door reverser for the ROLLS-ROYCE Trent engine and covers: Thrust Reverser door structure predominantly in composite. Acoustic treatment with composite sandwich. IFS design with carbon bismaleimide material This reverser will be used on MD11 and Airbus A330 aircraft.
1990-09-01
Technical Paper
901987
Jerry T. Callaghan, Robert H. Liebeck
In response to the NASA query, “Is there an aerodynamic renaissance for the long-haul transport?” a study was performed using both evolutionary and revolutionary airplane design concepts. The airplanes that resulted from both concepts offered performance improvements over existing transport airplanes which support a definite “yes” to the NASA question.
1990-09-01
Technical Paper
901988
Robert M. Kulfan
There is a significant potential for improvements in cruise aerodynamic efficiency of supersonic aircraft through improved design methodology, friction drag reduction, innovative design and the use of favorable interference concepts. The use of favorable aerodynamics concepts such as supersonic biplanes, ring wing, parasol wing and caret wings for the design of a small supersonic aircraft is discussed. The parasol wing concept is shown to offer the greatest potential for improvements in lift/drag ratio relative to a conventional design. However, the best aerodynamic concept is very dependent on the design Mach number, and on the airplane component size relationships. Optimized nacelle installations for a High Speed Civil Transport, HSCT, have aerodynamic interference effects similar to the parasol wing concept.
1990-09-01
Technical Paper
902018
Viggo Lofsgaard
This paper seeks to highlight some of the problems related to deregulation of the airline industry as seen by a major European airline. While deregulation hit the U.S. industry fast and hard, the European operators could enjoy a more slowly emerging relaxation of the traditional tight government control. Nevertheless, the increased competition encountered on the European arena the last ten years has called for decisive action and revised strategies in order to survive. On the basis of the U.S. experience and the general trend in Europe particularly, Scandinavian Airlines (SAS) set out to reorganize the structure of the company and adopt new strategies for the future. In order to anticipate the different markets emerging, SAS established clear quality priorities. Thereafter the company specified standards and goals for some defined strategic operational areas.
1990-09-01
Technical Paper
902016
Cheng-Ching Chi
The characteristics and capabilities of a recently qualified 5.08-cm (2.0-in.) diameter rotary actuator are discussed in this paper. This newly developed actuator has the smallest diameter of any rotary actuator currently used in an aircraft flight control system. This actuator is a part of the leading edge flap actuation system developed for a new thin-wing fighter. The unit has accumulated 17,500 equivalent flight hours in laboratory endurance testing and is currently being flight-tested.
1990-09-01
Technical Paper
902005
C. W. Anderson, Charles R. McClinton, R. Wayne Guy
America's entrée in the world of hypersonics is spearheaded by the National Aero-Space Plane program. Although the concept of hypersonic flight at speeds above Mach 6 has been investigated before in many countries, the efforts begun in the 1960's in the United States did not result in a major new capability. Many valid principles were examined, a good data base was developed, but a demonstration was not pursued with the priorities assigned to the space program at that time. During the 1970's, our hypersonic effort dwindled to a few dedicated research efforts which refined propulsion, aerodynamics, and computational fluid dynamics principles. To make real progress in the 1980's, and beyond, a focus and a rekindled effort was needed. The National Aero-Space Plane program provides that focus of activities.
1990-09-01
Technical Paper
902004
R. I. Scoville, M. J. Maxwell
Abstract This paper presents the results of an investigation to improve design/analysis techniques for aircraft hydraulic systems. A design/analysis tool was developed by integrating control-surface commands and loads obtained from Aircraft Dynamic Simulator Software (ADSS) with an enhanced version of the HYdraulic TRansient ANalysis (HYTRAN) program. Control-surface commands and loads from an ADSS simulation of a selected maneuver were used as dynamic input to the HYTRAN program so that the hydraulic system response could be predicted throughout the maneuver. Predicted hydraulic system pressures and control-surface positions from the HYTRAN simulation of the maneuver were compared to flight-test data and were found to be in excellent agreement. The successful coalescence of the two independent software programs gives engineers a concurrent design/analysis tool that can be used to optimize hydraulic system designs during the very early stages of design.
1990-09-01
Technical Paper
902003
Brian J. Bang, James G. Draxler
This paper describes a dynamic aircraft hydraulic system simulator model. This model uses a flexible approach that accounts for flight control loads, system stiffness, line losses, internal leakage at individual valve packages, pump compensator response, and power input to engine-driven pumps at various engine rpm. The model integrates performance of the flight controls, hydraulics, and power sources allowing accurate simulation of the airplane.
1990-09-01
Technical Paper
902002
Paul G. Stringer
: Human error remains as the major cause/factor identified in both civil and military helicopter accident reports. This paper identifies some opportunities for improving helicopter operational performance and reduce human error accidents based on critical event analysis of accident reports and associated operational requirements. Analysis identified areas where the pilot was overloaded and information available to the pilot was inadequate for the particular situation. These results suggest several areas where the task demands could be made more compatible with the pilot capabilities for improved performance, fewer errors, and timely decisions in critical situations. Two areas addressed are power/flight performance management and obstacle avoidance. This information can be useful in developing helicopter automation and electronic display systems that improve safety and mission reliability.
1990-09-01
Technical Paper
901997
James G. Draxler
As most modern large commercial transport aircraft use fully hydraulic powered flight controls, the loss of all hydraulic power is a catastrophic event. Loss of all hydraulics may be caused by either external or internal events. These are rare in occurrence and sometimes difficult to predict. Available options for preventing total hydraulic loss fall into two categories: system installation/redundancy options and system shutoff devices. This paper discusses the advantages and limitations of each approach and how they differ depending on whether they are applied to a new airplane or are used to retrofit older airplanes.
1990-09-01
Technical Paper
902024
Ron Livecchi, Ron Bartels
Flight and engine controls for advanced development aircraft are required to be more ballistically tolerant, lighter, thermally resistant and EMI/EMP resistant than conventional controls. The two technologies identified as a prime paths to achieve these goals are composite materials and fiber optics - the composites will provide improved ballistic survivability, increased thermal resistance and reduced component weight; the fiber optics will provide lighter system weight and improved EMI/EMP resistance. As a portion of a major ongoing IR&D effort, Moog has developed a servoactuator that uses these technologies. Materials and fiber optics development has produced a light weight, conventional temperature actuator. The control valve used in the demonstration hardware is Moog's small direct drive valve (DDV). We do have conventional electrohydraulic servovalves (EHSV) that are optically powered.
1990-09-01
Technical Paper
902022
R.M. (Fred) Klaass, Mark M. Harris, David N. Marsh
This paper describes the design of an advanced emergency power system meeting future More-Electric aircraft demands for starting at 50,000 feet (16,000 meters) and acceleration to full power in two seconds. This rapid starting requirement stems from the need for uninterrupted electric control power in the event of main engine shutdown at high altitude. Key to developing this power system is a flexible-cycle (flex-cycle) combustor. The combustor, with other shared auxiliary power unit (APU) components, constitutes an Integrated Power Unit (IPU). The IPU, gearbox, and stored energy components form the aircraft secondary power system. The flex-cycle combustor design accommodates a high exit temperature, a rapid temperature rise, and a high heat-release rate. High combustor performance is achieved with thermal barrier coatings, effusion cooling, and air-assist atomizers. The flex-cycle combustor design, IPU starting analysis, and proposed development test plan are discussed.
1990-09-01
Technical Paper
902021
Hal Sprogis
Five years ago, a new experiment in passenger air transportation for Atlantic Ocean crossings was introduced. It was given the acronym known as ETOPS and involves the development of passenger aircraft having only two-engines utilized for flights over such critical routes. The essence of the concern generated in this study is summarized by the safety analysis of Dr. Robert Besco, who states, “ETOPS is troublesome because the failure of only one system on an aircraft [In this case an engine] should not cause that aircraft to have to operate under emergency conditions.” Previously, a major cornerstone of civil aviation safety was the concept of providing multiple engine redundancy with a minimum of three-engines required for such critical flights.
1990-09-01
Technical Paper
901680
Rick P. Tortomasi
Abstract The hydraulic industry has come to understand the importance of proper filtration. The other half of contamination, that is prevention, still needs to be improved. Research has provided the facts, now industry must implement the hardware to put prevention into practice.
1990-09-01
Technical Paper
901708
Hiroshi Nagase, Yoshihisa Harata, Mitsuharu Takigawa, Keiji Aoki, Shinichiro Tanaka, Tokuta Inoue
Electronic Control Units (ECUs) for automobiles are usually composed of a main single-chip microcomputer and peripheral circuits with some standard and/or custom ICs. The peripheral circuits vary with the kinds of control or models of automobiles. When the peripheral circuits are replaced with a single-chip microcomputer, the ECU becomes compact and low in cost. This is because the ECU is constructed with only two LSIs and can be used for various kinds of control and various models of automobiles only by changing the program of the microcomputer. The microcomputer, however, requires many I/O functions and high reliability. We have developed a new 4-bit microcomputer suitable for these requirements. The new microcomputer has two remarkable features. One is powerful I/O functions such as high speed I/O, serial I/O, parallel I/O, analog I/O, and default output that is generated in place of the calculated output by the main CPU when it fails.
1990-09-01
Technical Paper
901719
Patrick Torossian, Daniel Lanphear
Abstract Module Thermal Analysis (MTA) is a program to evaluate and compare the thermal characteristics of various transistor and IC package positions in the Electronic Engine Control (EEC-IV) module. The design engineer can select transistor and IC wattages and their locations on the new EEC-IV housing. After the design engineer has chosen and located the devices on the MTA module housing, the program creates an input file which is submitted to a finite element analysis program called ANSYS. This is done through DIGITAL's ALL-IN-1 menu-driven interface which also includes a custom library of devices and wattage combinations to choose from. ANSYS uses the wattage information to determine IC die temperatures of all the devices and generates a color plot showing the temperature isotherms throughout the module. The die temperature output analysis is returned to ALL-IN-1 and stored with the corresponding module layout, which correlates the housing die temperature to each device.
1990-09-01
Technical Paper
901722
Marion Lineberry, Cynthia Martin
Abstract Applications in electronic mapping are gaining in popularity because of the increased availability of both digital roadmap databases and sophisticated graphics processing capabilities. Based on this technology and using information provided by vehicle navigation and traffic reporting systems, we've developed an automated navigation system, called the Driver's Assistant, that plans and schedules routes for vehicles travelling on city streets. Texas Instruments initiated the Driver's Assistant program to develop the required technology to meet the needs of customers building automotive electronics systems. This paper summarizes the progress of the Driver's Assistant program toward achieving two objectives: (1) feasibility of real-time route planning, dynamic replanning, and route scheduling using very large digital road maps (2) compatibility with both portable, digital traffic reporting and automotive navigation systems.
1990-09-01
Technical Paper
901725
Kenji Kaida, Nagayoshi Matsubara, Chikaaki Minai, Yoshiro Hayashi, Ryuichi Masuda, Minoru Uozumi
This paper describes a technology and its application to V8 type closed deck aluminum cylinder blocks for the LEXUS LS400. The low pressure casting method is generally used for the manufacture of high quality aluminum blocks with the closed deck shape. The method is. however, not suitable for mass production due to its low productivity. The newly developed casting method is a kind of differential pressure type casting method such as the low pressure casting method. The characteristic feature of this new method is to suck up the molten metal and to feed it into a die. Since the air in such a die is easily exhausted by this method. the efficiency of feeding molten metal into a die is positively improved. Owing to this new technology, high quality closed deck aluminum blocks can be manufactured with high productivity.
1990-09-01
Technical Paper
901660
S. A. Lukowski, P. W. Claar, R. A. Fiedler
An analytical study of the directional behavior of a tractor-semitrailer vehicle with steered trailer axles is discussed. The model was used to determine the influence of design parameters and steering inputs on the directional behavior of the tractor-semitrailer combination with steered trailer axles. Results obtained from the computer simulation study indicated that the maneuverability of an articulated vehicle with steered trailer axles was improved. The influence of fifth-wheel location with respect to tractor cg on the vehicle directional behavior in a steady-state turning maneuver was also investigated. Fifth-wheel locations near the tractor cg were most effective in reducing the angles of sideslip and articulation.
1990-09-01
Technical Paper
901663
J.W. Adams, R.A. Stein, G.F. Leydorf, M.J. Schrader
Abstract Two-stroke cycle direct injection engines can achieve adequate stability at idle with stratified combustion at very lean overall air-fuel ratio, but exhaust temperature is very low. A rotary valve system was designed to spill charge from the cylinder into the intake tract during the compression stroke, in order to allow stable operation at lower engine delivery ratio and thereby increase exhaust temperature. Reduction of the engine delivery ratio was not achieved due to the poor scavenging characteristics of the swirl liners used, which resulted in high content of exhaust residual gas in the spill recirculation flow. Although the concept objective of higher exhaust temperature was not realized, the results indicate that the concept may be feasible if high purity of the spill recirculation flow can be achieved in conjunction with high trapping efficiency.
1990-09-01
Technical Paper
901666
Robert J. Kee, Gordon P. Blair, Roy Douglas
This paper describes an experimental comparison of loop and cross scavenged single-cylinder research engines. The cross scavenged engines have employed the QUB type deflector piston. The initial results show that the QUB cross scavenged engine exhibited inferior performance characteristics. Utilizing the QUB single cycle test rig, a study of the QUB cross scavenging system has shown that the bore-to-stroke ratio significantly influences the scavenging behaviour; reduction of the bore-to-stroke ratio from over-square values gave improved characteristics. On the basis of this finding, a new cross scavenged cylinder barrel was designed. In a subsequent series of dynamometer tests, improvements in power, fuel economy and emission characteristics were recorded for the new cylinder. These improved results approximate closely to those recorded for the loop scavenged engine and are considerably superior to those of the original cross scavenged cylinder.
1990-09-01
Technical Paper
901667
R. Fleck
The importance of exhaust system design for three cylinder two-stroke engines is demonstrated using a thermodynamic model developed at The Queen's University of Belfast. The influence of the major exhaust parameters on wide open throttle power and bmep is investigated. In addition, the potential benefits of reed valve induction over piston port induction at low engine speeds are demonstrated for one particular engine configuration.
1990-09-01
Technical Paper
901668
R. Fleck
A thermodynamic model developed at The Queen's University of Belfast is used to demonstrate the importance of exhaust system design for four cylinder two-stroke engines. The investigation considers two exhaust layouts for in-line engines and also a V or opposed piston layout. The influence of the major exhaust parameters on wide open throttle power and bmep is investigated.
1990-09-01
Technical Paper
901675
Douglas A. Bargiel
A new sweeper/scrubber was developed by Clarke, American-Lincoln to fill a product need for a mid-size scrubber and take advantage of an all electric design. This paper discusses the design and features of the Model 6200 Sweeper/Scrubber.
1990-09-01
Technical Paper
901678
John G. Eleftherakis
The analysis and description of field generated containment in fluid systems (hydraulic or lubricating oil, fuels, water, etc.) continues to be one of the best indicators of system “health.” The monitoring of the contaminant provides an effective health measure by accurate determination of the contributing factors to system degradation. These include solid particles, water, additive depletion, and a host of resultant synergistic effects such as sludges, gels, etc. Their are many options available for field fluid analysis. Five specific analyses have been found to provide an extensive description of field contaminants. They are particle counting, gravimetric level analysis, proton induced X-ray emission (PIXE) analysis, ferrographic wear debris analysis, and water content analysis. Thorough descriptions of this procedures is provided with detailed application considerations.
1990-09-01
Technical Paper
901679
Gabriel Silva
This paper is concerned with the synergistic effects of pump wear modes. The objective is to investigate the wear produced by cavitation, adhesion, abrasion, and corrosion and to verify a proposed model of the synergistic pump wear process. The approach followed includes identification of the combined effects of different wear modes (synergisms) in a pump and the development of a synergistic wear model that includes pump operating and environmental conditions as trigger factors of wear modes. An experimental program was designed to evaluate the cavitation, adhesion, and corrosion wear effects in conjunction with the abrasive wear produced in a pump by measuring wear debris, particle size and gravimetric levels of fluid. The generation of wear was traced to different pump locations. The results obtained here suggest that improved pump design and longer pump service life can be obtained when synergisms between failure modes are properly understood.
1990-09-01
Technical Paper
901787
Christopher D. Williams
An evolutionary extension of military aircraft Built-In-Test has been developed for armament systems. This extension, Wrap-Around-Test shows promise in replacing conventional support equipment currently used to test aircraft interfaces prior to weapons loading and during system maintenance. Wrap-Around-Test offers the ability to verify weapon system integrity at a reduced cost, improved operational readiness and enhanced ergonomics.
1990-09-01
Technical Paper
901768
William B. Ribbens, Giorgio Rizzoni
Abstract The integrity of the exhaust emission system in a passenger vehicle can best be maintained by monitoring its performance continuously on board the vehicle. It is with the intent of monitoring emission system performance that the California Air Resources Board has proposed regulations which will require vehicles to be equipped with on-board monitoring systems. These proposed regulations are known as OBDII and will probably be followed by similar Federal EPA regulations.This paper discusses a method of monitoring engine misfire as part of the OBDII requirements for passenger vehicle on-board diagnostics. The method is relatively inexpensive in that it uses an existing sensor for measuring instantaneous crankshaft angular position, and utilizes electronic signal processing which can be implemented in relatively inexpensive custom integrated circuits.
1990-09-01
Technical Paper
901789
Larry J. Herrig
Abstract Many environmental/reliability test requirements are specified for electronic equipment on military/commercial applications. The utilization of the fatigue relationship in MIL-STD-810 can be used to compare the severity of the various tests and aid in the effective evaluation of such requirements.
1990-09-01
Technical Paper
901788
Richard Rawlings
Abstract There is evidence that for some types of aircraft electronics equipment, reliability and development growth testing (RDGT) is very effective. However, it has been a slow and difficult process to achieve. The accumulation of vibration damage and wear suffered by electronic equipment test articles during RDGT is a function of the input vibration (random) levels and test durations. Dependence only on design specification requirement input vibration levels and durations to determine RDGT test parameters can lead to excessive overtest. It has been found that excessive accumulations can result from unexpectedly high nonlinear responses. The test article qualification vibration specification requirement levels and durations are also often pivotal in determining the RDGT vibration input level. This approach can lead to rapid overtest where long-duration vibration exposure occurs, such as in RDGT.