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Viewing 70801 to 70830 of 109896
1991-09-01
Technical Paper
912144
Bruce T. Clough
Abstract Recent concerns about the susceptibility of digital flight control systems (DFCS) to electromagnetic interference (EMI) have lead to testing a representative DFCS for upset from possible carrier signal modulations.
1991-09-01
Technical Paper
912140
Harry W. Orlady
Advanced technology aircraft were a major advance in air transport. They are the aircraft of our immediate future. Training for these aircraft is extremely important. It furnishes the interface between the manufacturer, the operator, and the pilot. It is very expensive. Neither the manufacturers, the airlines, nor the independent training organizations can afford to do it poorly. Historically, most changes in training and in airline flight operations have been evolutionary, not revolutionary. However, there have been some truly generic changes and in the past few years at least two new training concepts -- LOFT and CRM. Several issues associated with the training and operation of advanced technology aircraft have been clarified since their inauguration.
1991-09-01
Technical Paper
912173
Ed Taylor, Don Croke, Eric Speck
The simplicity, reliability, and weight reduction potential promised by high voltage direct current (HVDC) electrical power systems has enticed aircraft developers to propose the use of such systems in modified form for advanced aircraft. However, HVDC systems have not been flown on any military or commercial aircraft and little has been done to independently validate the tradeoffs made and to analyze the impact a HVDC system will have on Naval aviation and its support. To rectify this, the Naval Air Systems Command established a working group consisting of Defense Department activities concerned with aircraft electrical power research and development, testing, avionics development, logistics, and safety. The working group was free to examine all aspects of the development, implementation, and use of HVDC aircraft power systems.
1991-09-01
Technical Paper
912162
D. Collard
A survey of the CONCORDE supersonic transport aircraft programme has been made, starting from initial studies in the late 1950's and ending with the proposed developed type B version. The survey covers the aspects for which aerospatiale in France was responsible, with only a minimum of reference to BRITISH AEROSPACE items, covered in another paper. Much knowledge can be drawn from the study of the technical development of this unique aircraft and it is hoped that this paper will help pass this knowledge on.
1991-09-01
Technical Paper
912157
Pamela A. Davis, Veloria J. Martinson, Thomas J. Yager, Sandy M. Stubbs
Preliminary results from testing of 26 X 6.6 radial-belted and bias-ply aircraft tires at NASA Langley's Aircraft Landing Dynamics Facility (ALDF) are reviewed. These tire tests are part of a larger, on going joint NASA/FAA/Industry Surface Traction and Radial Tire (START) Program involving three different tire sizes. The 26 X 6.6 tire size evaluation includes cornering performance tests throughout the aircraft ground operational speed range for both dry and wet runway surfaces. Static test results to define 26 X 6.6 tire vertical stiffness properties are also presented and discussed.
1991-09-01
Technical Paper
912155
Peter C. Vorum
Ground operations over rough surfaces and/or debris strewn taxiways and runways may result in cut damage to the tires. Cut progression during continued flight operations has not been seriously studied. This report will follow a group of Type VII Extra High Pressure tires which were damaged by running them over a debris strewn test bed, then run through alternating taxi-takeoff and landing-taxi tests on the 3.05 meter (120 inch) dynamometer in the Landing Gear Development Facility at Wright-Patterson Air Force Base. Only 1.3 - 23% of the debris struck by these tires resulted in cuts. While testing on the dynamometer, the cut depth grew rapidly until it reached the outer carcass ply, then slowed. The test group included new and recapped bias ply, and prototype radial main landing gear tires. This paper will summarize the tire tests and offer recommendations for future evaluation of the tires and materials.
1991-09-01
Technical Paper
912177
Colin Rodgers, Jack Shekleton
Future fighters will require more compact, lighter weight, small gas turbine auxiliary power units (APUs) capable of faster starting, and operation, up to altitudes of 50,000 ft. The US Air Force is currently supporting an Advanced Components Auxiliary Power Unit (ACAPU) research program to demonstrate the technologies that will be required to accomplish projected secondary power requirements for these advanced fighters. The requirements of the ACAPU Program represent a challenging task requiring significant technical advancements over the current state-of-the-art, prominent among which are: Small high heat release high altitude airbreathing combustors. High temperature monolithic ceramic and metallic small turbines. Capability to operate, and transition from non-airbreathing to airbreathing modes. This paper discusses these challenging requirements and establishes technology paths to match and exceed the required goals.
1991-09-01
Technical Paper
912183
R.E. Niggemann, S. Peecher, G.I. Rozman
Abstract Sundstrand has been investigating 270-Vdc/hybrid 115-Vac electrical power generating systems (EPGS) technology in preparation for meeting the electrical power generating system (EPGS) requirements for future aircraft (1). Systems such as the one being investigated are likely to be suitable for the More-Electric Aircraft (MEA) concepts presently under industry and military study. The present Sundstrand single-channel testbed is being further expanded to better understand the electrical system performance characteristics and power quality requirements of an MEA in which traditional mechanical subsystems are replaced by those of a “more-electric” nature. This paper presents the most recent Sundstrand 270-Vdc system transient performance data, and describes the modifications being made to the 270-Vdc/hybrid 115-Vac testbed.
1991-09-01
Technical Paper
912186
Michael J. Cronin
This paper describes the technologies pursuant to more electric aircraft. The title “More Electric Aircraft” is an appropriate appellation to describe the inexorable trend towards the use of more electrics in future advanced military and commercial aircraft. This trend is sponsored and supported by the U.S. Air Force/WRDC, USN/NADC and NASA. Most recently, the Department of the Air Force issued a solicitation with the acronym MADMEL: Power Management and Distribution for More Electric Aircraft. This is a major multi-year program which includes a MADMEL ground demonstrator and flight testing of electric technologies that will replace the several multiple power sources now resident in current aircraft.
1991-09-01
Technical Paper
912184
I.S. Mehdi, R.N. Johnson, W.J. Hastings
Boeing has designed and built an unmanned experimental Autonomously Piloted Vehicle called Condor, which has successfully flown. The flight control surfaces are operated using four basic types of electromechanical actuators (EMAs). A common controller design is used to operate all EMAs. This airplane utilizes only electrical secondary power to operate all the subsystems in the vehicle. So it is truly an “All Electric” airplane. This paper describes the Condor flight control actuation, propulsion control actuation, and electrical power generation and distribution systems. Each propulsion system is controlled by a single full authority digital Control Electronics Unit (CEU) with electrical actuators. A separate electronic Ignition Control Unit (ICU) drives the spark plugs, processes camshaft position sensors, and sends speed signals to the CEU and the mission computer.
1991-09-01
Technical Paper
912185
Edward J. Woods
Abstract The Boeing Company is investigating a High Speed Civil Transport (HSCT) aircraft which will transport 300 passengers at speeds up to Mach 2.4. Such a high speed, high altitude aircraft presents unique environmental and safety requirements. The aircraft electrical power system configuration must provide the required redundancy and reliability necessary to supply power for fly-by-wire flight control buses as well as other aircraft loads. Emergency power backup must be considered for various power failure conditions. This paper presents some of the issues affecting the electrical power system design, and some of the possible solutions which will be considered.
1991-09-01
Technical Paper
912216
C.F. Barth
A wide variety of manufacturing operations are utilized to fabricate the complete spectrum of components necessary for contemporary aircraft. Compounding the challenges inherent in utilizing these diverse manufacturing operations are the stringent quality, weight, and cost requirements for flight critical hardware. The industry maintains continuing efforts to meet these challenges with innovations in both component design as well as manufacturing technologies. The Jet Die Division of Barnes Aerospace Group, as a supplier of fabricated components to the aerospace industry, has participated in continued development of related manufacturing technologies. This paper addresses a specific advance in fabrication technology that will have wide applications for both airframe and engine requirements. Inherent with any advances in manufacturing technology are the emergence of new challenges to maximum utilization of that technology.
1991-09-01
Technical Paper
912219
Hyunik Yang, Daivd A. Hoeltzel
Abstract An approach for the automatic generation and refinement of three dimensional finite element meshes subdivided by rigid body movable subdomains has been developed. A combination of computational geometry and geometric modeling techniques have been employed to implement parametric computer-aided design based on the finite element method. To demonstrate the utility of this approach to parametric redesign, a series of meshes that model a hip joint prosthesis and a reciprocating internal combustion engine have been generated.
1991-09-01
Technical Paper
912212
Richard Johnson
The continued safe operation of the U.S. commercial airplane fleet will depend upon the ability to anticipate required adjustments in the inspection and maintenance activities to compensate for the “aging” process. Increasing numbers of aircraft are exceeding their economic design life--the age at which they have historically been retired from major airline service. Presumably, commercial aircraft are designed for “infinite life with proper maintenance.” But public confidence in operators abilities to properly maintain older aircraft significantly diminished following the widely publicized failure of the Aloha Airlines Boeing 737 fuselage in 1988. The FAA established the National Aging Aircraft Research Program to address this diminished public confidence in the airlines' ability to properly maintain their older aircraft.
1991-09-01
Technical Paper
912225
Steve Last, Martin Alder
The Airbus A320 has an autothrust system which is unique among transport aircraft in not having feedback movement provided to the pilots' thrust levers. There has been some controversy in the airline world over the operational aspects of this system. As British Airways was one of the earliest operators of the type, a survey was conducted to determine the views of line pilots as to the advantages and disadvantages of the system compared with conventional moving levers. This paper contains the results of that survey. It was concluded that the A320 design provides advantages in respect to engagement and selection of rated power settings, and that movement provides better disengagement and information on system function. BA concludes that from a Flight Operations perspective a future system should consider providing movement between the idle and climb power positions, whilst retaining the A320 thrust setting and engagement “detents” technique.
1991-09-01
Technical Paper
912232
Nikos Mills, Todd Lawson, Jan Roskam
The design and recovery considerations are presented for a staged supersonic transport (SSST). It is shown that the SSST offers economic benefits over the conventional SST. The SSST benefits from the ability to “optimize” the design for minimum drag during supersonic cruise without the penalties of: landing gear, extensive flaps for landing, and the meeting of FAR 36 noise requirements. The recovery considerations are also presented to validate the SSST concept.
1991-09-01
Technical Paper
912222
Charles O. Masters
Deicing and anti-icing of aircraft prior to flight in hazardous precipitation including snow, freezing rain, freezing drizzle and other conditions conducive to aircraft surface icing has become the main method for removing and preventing the freezing of contaminants on aircraft wings, control surfaces and other critical components. In turn the Federal Aviation Administration (FAA) has promulgated requirements that endorse a “Clean Aircraft Concept” for aircraft that operate under the various Federal Aviation Regulations. Recent advances in aircraft deicing and anti-icing methodologies, materials, equipments and procedures have fostered the need for a review and possible updating of FAA advisory and regulatory materials and other information on the subject. This paper discusses, in general, ongoing efforts to enhance aviation safety relative to aircraft ground deicing and anti-icing, and related ground operations in hazardous weather conditions conducive to aircraft icing.
1991-09-01
Technical Paper
912224
Richard G. Hill, Constantine P. Sarkos, Timothy R. Marker
This paper outlines a program that could ultimately lead to design standards for an onboard aircraft cabin water spray system to suppress postcrash fires. A brief summary of the program and the status of current activities is presented. The latter includes full-scale effectiveness tests, a study of possible problems arising from the inadvertent (or intentional) discharge of the system, and computation of the potential benefits (lives saved) from the mandatory requirement of such a system. The bulk of the paper describes the results of full-scale tests under several postcrash fire scenarios to measure the increased survival rate when using a water spray system. It is shown that a water spray system may provide passengers 2 to 3 minutes of additional time to escape under certain postcrash fire scenarios.
1991-09-01
Technical Paper
911994
Masahiko Onda, Yasushi Morikawa
A novel type of airships or a powered LTA aircraft has been proposed, which is designed with a rather conventionally shaped hull and with conventional thrusters and is not made as a control configured vehicle(CCV) nor utilized any sophisticated control mechanism. None of control surfaces are installed but couples of stabilizers equipped to the aft hull, and without any active control tricks the vehicle holds its stability and realizes enhanced maneuverability performances. This newly conceived type model is named as ‘ACROSTAT’. This airship can ascent and descent vertically, and can perform somersaults, spiral flights, and rotates around its C.G. as the center of the movement. The paper deals with the structural design concept of the model, design data and the attitude control principle.
1991-09-01
Technical Paper
912003
Kozo Fujii, Yoshiaki Tamura
Newly developed zonal method using the interface scheme based on the Fortified Navier-Stokes concept is applied to steady and unsteady flow problems. Two computational results are shown as application examples to unsteady flow problems. One problem is a train moving into a tunnel and the other problem is a blast wave propagation. These problem require the accuracy enhancement and the problem adaptability, both of which are important obstacles of the current CFD technology. The computed result indicates that the present method alleviates the difficulty with simple modification of the existing codes. Steady flow problems include supersonic intake flow simulation and three dimensional simulation of the complex body configuration. The results indicate that the present method alleviate the difficulty of the simulation of complex flow configuration.
1991-09-01
Technical Paper
911995
Shohei Niwa, Masayuki Suzuki
Abstract Making use of advantages of ducted fan, i.e. compactness and approachability, ducted fan VTOL can be used for many purposes, such as construction and servicing of the tall structures, rescue, etc.. In this paper the development of a working platform which utilizes the ducted fan VTOL concept is tried. Two types of ducted fan VTOL research models are developed. One is driven by electric motors and the other by an engine. The aim of the development is to investigate the ability of the ducted fan VTOL as a platform for working tasks at a high position. One of the most important problems for the development of the working platform in air is the development of control system which enable precision hovering. In this paper mainly the automatic flight control system for ducted fan VTOL is investigated and the control problems are studied which will arise when the VTOL is utilized as a working platform.
1991-09-01
Technical Paper
912006
Gary Trippensee
The X-29A forward-swept wing flight research aircraft flight envelope was expanded to 66°-angle of attack in 1990. This work was accomplished at the NASA Dryden Flight Research Facility in Edwards, California, using Grumman aircraft and United States Air Force personnel assistance. The flight envelope expansion was accomplished through a carefully planned buildup approach using the number 2 X-29 aircraft and a well documented high-angle-of-attack database established from wind-tunnel results, radio controlled subscale drop model results, and from previous X-29 aircraft number 1 flight data below 22.5°-angle of attack. Following the flight envelope expansion, a military utility evaluation was conducted to investigate the tactical utility of the X-29 configurations at high-angle-of-attack, slow-speed flight conditions.
1991-09-01
Technical Paper
912010
Hirotoshi Fujieda, Hitoshi Takahashi, Yoshit Miyamoto, Junichi Miyashita, Kenji Sakai, Yoshio Morita
“ASKA” developed by National Aerospace Laboratory (NAL) is a quiet, short take-off and landing (QSTOL) research aircraft adopting upper surface blowing (USB) concept as a powered high lift system. To achieving sufficient STOL performance by augmenting stall angle of attack and roll control power, blowing BLC technique was applied to the outboard leading edges and ailerons.Supplied high pressure air to save the BLC piping space,the BLC system which was fit for use of high pressure air was developed. The BLC system, in which BLC air is discharged by a series of discrete jets from small drilled holes (0.8 ∼ 3.0 mm in diameter) arranged in a raw, is one of the unique features of the aircraft. In this paper, the summaries of aerodynamic development of the BLC system are described except for the air piping system.
1991-09-01
Technical Paper
912005
David J. Moorhouse, James A. Laughrey
The STOL and Maneuver Technology Demonstrator (S/MTD) Program has validated a set of technologies that give a supersonic fighter all-weather Short Takeoff and Landing (STOL) performance while also enhancing up-and-away maneuverability. Significant reductions in both takeoff and landing distances, compared with the unmodified F-15, have been measured. The additional pitch control power of thrust vectoring has been demonstrated up to 30° angle of attack. The effectiveness of up-and-away reversing has been identified. First, major flight test results are presented and then lessons learned from this integration program are discussed.
1991-09-01
Technical Paper
912008
Tuncer Cebeci, John E. King
Abstract An interactive boundary-layer method is described for computing three-dimensional transonic flows on wing/body configurations. The method combines Euler solutions with viscous flow solutions obtained from an inverse boundary-layer method with an interaction law based on the extension of the Hilbert integral formulation used for two-dimensional flows. Depending on the complexity of the flowfield, two versions of Keller's box scheme are used, the regular box scheme in regions of positive crossflow and no separation, and the characteristic box scheme in regions of negative crossflow and flow separation. Preliminary calculations performed for a modern transport wing show good agreement with experimental data and indicate that wing/body configurations in transonic flows can be analyzed with good accuracy with this method at substantial savings of computer time.
1991-09-01
Technical Paper
912021
Junichi Miyakawa, Takeshi Ohnuki, Nobuhiko Kamiya
Forward swept wing (FSW) is known to have excellent performance relative to aft swept wing. The practical application, however, has been limited due to its structural divergence characteristics. The current progress in materials, especially anisotropic composites has opened up new future for FSW. This paper describes design study of FSW for transonic transport looking for high drag divergence performance. Inverse code is applied to FSW aerodynamic design to achieve isobar design concept. The performance is verified by transonic wind tunnel test. The paper also mentions the development of aero-structural integrated design tool, a combination of aerodynamic analysis code and structural analysis code, which is essential to FSW wing development.
1991-09-01
Technical Paper
912020
Jangsoo Choi, Yoshiyuki Sugiyama
The aerodynamic characteristics around a wing tip are investigated with a first order panel method. The geometry chosen for the study is a rectangular wing of aspect ratio 8.43,with RAF6 airfoil of 10% thickness ratio. The panel method gives similar aerodynamic characteristics to experimental ones even near the tip, such as a dominant suction pressure distribution present near the trailing edge around the tip, and the increase in the local lift and drag at the very narrow region of the tip. These properties are caused by the strong spanwise velocity component around the wing tip, the inviscid effects of which are described in detail, with respect to pressure coefficient, local lift and drag coefficients, downwash, and vorticity on the wing.
1991-09-01
Technical Paper
912033
Richard A. Peal
Abstract Technology has been the key to advancements in commercial transport airplane avionic systems over the past several decades. These advancements have included discrete operational improvements to existing functions and the addition of new airborne functions with the goal of improving economics, maintenance, and safety of flight. Technology in the 1990s will support new functions as well as multifunction integration. For commercial transport avionics it will bring economic, performance, maintenance, and safety benefits that have never before been achievable. Standardization, chip-level redundancy, modularization, and fault-tolerant designs will revolutionize the basic concepts for system design. Until now, most efforts to develop and apply technology advancements were carried on in a “federated” system atmosphere where even major functions of the total system were designed and developed without considering interfacing system functions.
1991-09-01
Technical Paper
912024
Osamu Muragishi, Seiji Nishio
Liquid reservation and liquid-gas separation system is an important factor in a thermal control system and an environmental control system of spacecraft. A surface tension tank is one of the important device in the system. A functional model and partial models were fabricated and their behavior verification tests were conducted under the microgravity. The experiment was conducted in NASA KC-135 reduced gravity plane in 1991 January. Expelling function was verified with a functional model. The tank has channels with fine mesh screen and expels liquid only. The expelled distilled water is returned into the tank again, the ratio of liquid to gas is kept constant, and the flow rate of the discharged water is a parameter. The liquid behavior was recorded on video tape and acceleration data was recorded on a data recorder.
1991-09-01
Technical Paper
912044
Shigeru Aso, Shouzo Maekawa, Masanori Hayashi
For the fundamental study of aerodynamic heating of winged vehicle and space planes in hypersonic flow the detailed structure of three-dimensional shock wave/turbulent boundary layer interaction region induced by sweptback sharp fins are investigated carefully by oil flow technique and pressure distribution. The major objectives of the present study are to study the effects of the shape of the leading edge of the fin to the flow fields on the body and to study the effect of the sweep angle of the leading edge of the fin to the interaction region. Also aerodynamic heating phenomena in the flow fields are investigated by using a new technique. For the measurements a new method of measuring heat flux developed by the present authors are used. The new method is based on a new type of thin-film heat transfer gauge with high spatial resolution and fast response.