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Viewing 70801 to 70830 of 107827
1990-09-01
Technical Paper
901761
Masaki Nakano, Toshifumi Hibi
Abstract This paper describes the results of an investigation into the controllability of a traction-drive type half toroidal CVT, built with traction-drive elements. One feature of this CVT is that it provides better power transmission efficiency at its rolling contact points than other traction-drive CVTs developed previously. Another feature is that ratio changes can be effected with only a slight power input. A third feature is that it does not require any special hydraulic system to engage the contact points of rolling elements because it is designed to generate engaging force spontaneously in proportion to the torque input. The first half of the paper presents an analysis of the shifting mechanism. The characteristics of ratio changes effected by slight displacements of the power rollers were analyzed theoretically. A simplified CVT model was then examined experimentally and found to provide good response characteristics.
1990-09-01
Technical Paper
901763
Hideo Nakamura, Hidehiro Minami, Toshimi Abo
Remarkable advances are being seen in automotive electronics nowadays. New concepts are being reported for next- generation control systems that provide vehicle performance which matches the driver's intentions and sensitivities. With these systems, inferences are made about the driver's perceptions and the driving environment, and the control parameters are adjusted automatically to achieve the drivability desired by individual drivers or for various driving conditions. This paper presents a control scheme that is intended to be a key technology of a total vehicle control system. The control scheme matches the axle torque characteristics resulting from accelerator inputs with those of the desired reference model, regardless of the original nonlinear characteristics of the mechanical components. The effectiveness of this method is shown by both computer simulation results and experimental data.
1990-09-01
Technical Paper
901762
Dugald Cameron, John Vorobel, Peter Resele, Richard Geno, Michael Adams, Bruce Donaldson
Abstract This paper presents the Chrysler 1991 Model Mini-Van All-Wheel-Drive (AWD) System. The AWD system is an enhanced traction system requiring no driver input or additional driving skills. It is transparent to the driver in that there is no perceived operating and/or handling difference relative to a front wheel driven vehicle. The system is aimed at safety and security in driving under all conditions. The paper further describes the design and development of the AWD vehicle system.
1990-09-01
Technical Paper
901750
H. Graefe, W. Krummheuer, V. Siejak
A computer program for the simulation of static deployment tests of airbags is introduced. The main output of the program is the pressure vs. time characteristic in the airbag. It also can be used for fine-tuning of the bag in accordance with the inflator characteristic by varying venthole area and fabric properties. This goes particularly for switching from coated to uncoated fabrics. The mass of gas, energy, temperature, and pressure is calculated at every time using the basic gas dynamic equations, inflator characteristic, seam leakage rate, opening pressure for the cover, fabric stretch, and suction of outside air into the bag. Special attention is given to the properties of uncoated fabrics. The air permeability of uncoated fabrics has been investigated extensively including the influence of thermal ageing. Some results of these tests are presented here in combination with steady state measurements of volume flow through airbags.
1990-09-01
Technical Paper
901759
H. J. Schoepf, G. Juergens
Since the introduction of the 4-speed automatic transmissions W4A040 in 1979 and W4A020 in 1981, more than 50% of Mercedes-Benz cars have been equipped with automatic transmissions. These transmissions have undergone continuous development since their introduction. Due to engine/transmission management, the kick-down shift points are electronically influenced, the shift comfort is improved partially by ignition timing manipulation. During the warm-up phase the shift points are raised via output signals from the electronic engine system to improve exhaust gas emissions. In this paper considerations are explained which resulted in supplementing the proven four-speed transmission with a five-speed transmission.
1990-09-01
Technical Paper
901746
Masami Aga, Hideki Kusunoki, Yukiharu Satoh, Ryouzou Saitoh, Masami Ito
This paper describes how the 2-degree-of-freedom control concept may be applied to an active front-and-rear steering control system. The configuration of the system is explained as is the manner in which the control strategy can be devised. Simulation and test results confirm that vehicle characteristics may be varied to achieve specific aims and that steering response and vehicle stability can be independently improved.
1990-09-01
Technical Paper
901748
Yuji Yokoya, Ryohei Kizu, Hiroshi Kawaguchi, Kaoru Ohashi, Hiroyuki Ohno
We adopted the active hydropneumatic suspension and the dual-mode 4WS system for the 1989 Toyota CELICA. The active control suspension system detects the vehicle state with various sensors to control the oil pressure in the hydraulic cylinder with the linear pressure control valve; controlling attitude, ride comfort, stability & controllability and three-level vehicle height. The 4WS system continuously changes the steering angle ratio between the front and rear wheel according to the vehicle speed, decreasing the minimum turning radius at a low speed by 0.5 m and improving the controllability at a medium speed and the stability at a high speed. In addition, we further improved the performance of each system by integrally controlling the active control suspension system and the 4WS system. Thus, we succeeded in improving the total performance of vehicle dynamics by adding ABS to these systems to control the vertical, lateral and longitudinal accelerations.
1990-09-01
Technical Paper
901749
C. S. O'Connor, M. K. Rao
The three dimensional crash victim simulation program, MADYMO 3D, was utilized to model the kinematics of a crash dummy. The crash dummy was modeled as a linkage system with a sliding contact between the pelvis and the lap belt to allow the simulation of submarining. For this study, submarining can be defined as the relative movement of the lap belt portion of an active or passive restraint system above the anterior superior iliac spine, ASIS, and onto the abdomen of the occupant. The results from the models were compared with results from generic rear seat HYGE sled tests. The results from the Hybrid II and Hybrid III dummy models were reasonably comparable to the sled test results. These dummy models were able to simulate the occurrence of submarining in the sled tests. The dummy models also were able to simulate trends in dummy accelerations once the times of submarining were matched.
1990-09-01
Technical Paper
901866
Seymour Salmirs, William H. Reed
A wind tunnel program examined front end modifications for Cab-Over-Engine tractors. A Design based on a wing airfoil was used to produce a wind weighted drag reduction of ten percent. The truck was considered to be a small aspect ratio “Wing” with a plane of symmetry on the road surface. The shape was able to achieve smooth flow at the vehicle side when the incoming flow was yawed from the truck's longitudinal axis. Drag measurements were made and tufts on the body and smoke off the body were observed. The wind tunnel results were supported by data obtained from a road test. Comments by operators currently driving equipped trucks tend to support the work and point to handling qualities advantages related to the design.
1990-09-01
Technical Paper
901860
Walter J. McGee
A wake up call has been placed for American Industry. Key major industrial deficiencies exist that threaten the implementation of the QUALITY processes. Corporate management is generally unaware of them. And the quality pundits have not recognized the magnitude of these problems within our nation's industries. The purpose of this report is to alert American business to the seriousness of this situation, and proposed national corrective action promoted by the National Standards Educators Association. Because unless checked, they will continue to impede the QUALITY objective and render the use of Statistical Process Control meaningless.
1990-09-01
Technical Paper
901857
John C. Vassberg, Kathleen B. Dailey, Douglas M. Friedman
Applications of and recent improvements to the AIRPLANE program (developed by Jameson and Baker) are presented. This unstructured-mesh Euler method is capable of solving the inviscid transonic flow about complex three-dimensional aircraft configurations. Preliminary validations for the ONERA-M6 wing are made with comparisons to test data and a structured-mesh Euler code. Geometric capabilities of the present method are illustrated with solutions about simple, semi-complex and extremely complex aerodynamic configurations. Post-processing techniques for unstructured-mesh solutions are also presented. Computational resources and manpower requirements are benchmarked for the ONERA-M6 wing and a generic MDC Tri-Jet transport; the computers utilized for this survey include CONVEX, CRAY, Hitachi and IBM.
1990-09-01
Technical Paper
901856
S. W. Singer, E. A. Mattson
A computational method based on a cell-centered, finite-volume spatial discretization and explicit time-stepping algorithm for solving the Euler and Navier-Stokes equations is used to simulate inviscid and viscous flow about configurations including a diverging nozzle, a 74 degree delta wing, and a Mach 6 Waverider. Solutions are obtained using patched multizone grids with both matching and different grid densities across zonal interfaces and are correlated with analytical solutions and experimental data. The computational results increase the confidence in applying Euler and Navier-Stokes solvers to the more complex mixed internal/external flows associated with complete aircraft configurations.
1990-09-01
Technical Paper
901855
Dong-Ho Lee, Oh-Hyun Rho, Chang-Joo Kim
A fast explicit multi-grid scheme proposed by NI has been applied to steady transonic flows around eight bladed SR-3 advanced turbo-prop. FVI(Finite Volume Integral) used in one step distribution formula was implemented more easily by representing Euler equations in cartesian coordinate system. One step distribution formula obtained from Lax-Wendroff type differencing were used only for coarse grid calculations without FVI, so the increase in computational work per iteration was about only 10% compared with 25% in full approximation scheme. And by using standard coarsening and straight injecton for restriction, no additional memory was needed. Artificial viscosity and boundary conditions were applied only in the finest grid level, so the efficiency of multi-grid scheme was nearly independent of them. About 60% saving in computing time was obtained with 4 levels of coarse grid.
1990-09-01
Technical Paper
901854
G. A. Miller, S. Agrawal
A computational analysis of the external flowfield about a fighter configuration was conducted to evaluate an Euler solver and to investigate a hybrid combination of an Euler solver and a panel method. The analysis demonstrated the usefulness of Computational Fluid Dynamics (CFD) as a configuration design tool. The configuration selected for the study involved complex flowfields for which substantial wind tunnel test data were available. The Euler code provided good estimates for the incremental effects of aileron deflections using both wing-alone and wing-fuselage modeling. In general, the addition of the fuselage to the wing-alone model improves estimates of the effects of leading edge and trailing edge flap deflections. Using a hybrid combination of Euler code results with incremental effects of the tails from a subsonic panel method provides good estimates of trimmed drag changes for small flap/aileron deflections.
1990-09-01
Technical Paper
901852
T. W. Purcell, C. J. Borland, E. N. Tinoco
Abstract A loosely coupled method for aeroelastic predictions of aircraft configurations is shown. This method couples an advanced structural analysis method with a CFD aerodynamics code in a modular fashion. This method can use almost any CFD code, so a validation of several such codes is shown to establish regions of validity for each code. Results from potential codes, an Euler code, and a Navier-Stokes code are shown in comparison with experiment. Viscous effects are included in most cases through a coupled boundary-layer solver or a turbulence model as appropriate.
1990-09-01
Technical Paper
901812
Ohyun Rho, Won Wook Kim, Chong Am Kim, Dong Ho Lee
The existing two-dimensional Euler code is extended to the three-dimensional flow problem in which the transonic flow around the double fin-body combinations was analysed. Ni's two-dimensional formulas are extended to the three-dimensional case and applied to the supersonic flow calculation over the double fin-body combinations. The numerical results have proved to be very accurate in predicting the pressure distribution and capturing the shock. The code extended to the three-dimensional flow analysis in the paper can be consequently used to estimate the aerodynamic characteristics of the complicated body.
1990-09-01
Technical Paper
901811
M. H. Lin, M. J. Sheu
A numerical method is developed to analyse the flow around an axisymmetric ogive-cylinder and an ellipsoid-cylinder bodies undergoing harmonic pitching motion in an uniform air free stream. The pressure distributions along the lengthwise and over the circumference of the body are calculated with fineness ratio of 3:1 at mean angle of incidence 0° and 5°. Results are presented for a range of frequency parameters and various mean angle of incidence in order to show the influence of the frequency parameter and the mean angle of incidence on the aerodynamic properties.
1990-09-01
Technical Paper
901810
Kevin W. Whitaker
A study was undertaken to improve the prediction of external (gas-to-blade) heat transfer coefficients in gas turbine engines. The study specifically investigated the effects of improved modeling of the eddy diffusivity of heat in the turbulence model. A two- dimensional boundary layer code, STAN5, was selected and modified by incorporating several different turbulent Prandtl number models. Results indicated that slight effects were attributable to the modified turbulence model. Boundary layer character (laminar, turbulent or transitioning) appeared to be much more significant.
1990-09-01
Technical Paper
901809
Clifford J. Obara, Paul M.H.W. Vijgen, Cynthia C. Lee, Michael S. Wusk
Correlation of in-flight boundary-layer transition experiments with linear boundary-layer stability theory contributes both to the validation of the numerical methods as well as the analysis of the measured transition process. Transition results obtained in a recent flight experiment, in which the extent of laminar flow and the transition process on the wing of a business-jet fitted with an instrumented glove section were determined, are analyzed. The experiment was conducted at freestream Mach numbers from 0.55 to 0.82, chord Reynolds numbers from 10 to 20x106, and leading-edge sweep angles of 17° to 20°. The growth of both Tollmien-Schlichting and crossflow instabilities are predicted using the en method for several flight conditions and the calculated “n-factors” at transition onset are correlated. Comparison of the measured dominant boundary-layer disturbance frequencies and the predicted unstable frequencies shows fair agreement for several of the flight conditions studied.
1990-09-01
Technical Paper
901808
Shen C. Lee, Chang R. Chen
Numerical solutions of the Reynolds-averaged Navier-Stokes equations were obtained with the two-equation K-ϵ turbulence model. Considering the low-Reynolds-number effect in the closed vicinity of a solid boundary, a stream function and vorticity method was developed to consider both the laminar and turbulent stresses throughout the two-dimensional, incompressible flowfield of any arbitrary geometry. At a low Reynolds number (Re = 30), the initially imposed disturbances around an airfoil are damped out; the flow is laminar. At a moderately high Reynolds number (Re = 1000), instability of laminar flow is obtained by exhibiting cyclic patterns in the stream function and vorticity distributions. Nevertheless, only laminar stress occurs in the entire flowfield. At a higher Reynolds number (Re = 106), turbulent stress, which is about three orders of magnitude larger than the laminar stress, occurs at a certain distance downstream of the leading edge and in the wake region.
1990-09-01
Technical Paper
901807
Michael J. Siclari, Paul Federico, Marc Mandel
A Computer Applications Laboratory (CAL) has been established at Grumman that is primarily concerned with the visualization of large sets of scientific data. The laboratory is a color graphics workstation environment and communications facility that allows scientists and engineers to quickly process and visualize large quantities of discrete data generated by an experiment or by a supercomputer numerical simulation. The graphical visualization capabilities are supported by in-house research into software development tailored to specific workstation hardware graphics. The CAL facility also serves as a site to the Numerical Aerodynamic Simulation (NAS) facility at NASA's Ames Research Center (ARC) allowing scientists, whose computer requirements involve massive physical memory, to access the CRAY-2.
1990-09-01
Technical Paper
901770
R. J. Meckstroth, R. Ahoor
: In the engineering design attempt to minimize customer complaints related to belt misalignment, a maximum belt pulley entry and pulley exit angle was chosen as a critical target for avoiding excessive belt wear and chirp noise. Calculating belt misalignment due to pulley misalignment from the perfect plane between two grooved pulleys is done using statistical stackup calculations in three dimensional space. This is usually done using available computer statistical simulation models and the most current component detail drawings. For backside pulleys (flat pulleys), such calculations can be performed only if the position of the belt as it contacts a backside pulley is known. Since the shape of the grooves no longer fixes the position of a belt at pulley entry point, the position of the belt at the backside pulley can not be determined by the position of the pulley groove.
1990-09-01
Technical Paper
901893
Kent Weber
Aerospace Planes are substantially different from both conventional aircraft and conventional rocket powered spacecraft and have a unique set of secondary power requirements. Although there are a wide variety of aerospace plane concepts incorporating both single and multiple stage to orbit, the various arrangements proposed have many common features. One of the primary common features unique to aerospace planes is the use of liquid hydrogen or liquid methane as the fuel. The cryogenic fuel storage temperature, while inconvenient from a fuel handling point of view, offers some synergistic cooling and power generation benefits unavailable to conventionally fueled aircraft. A second common, but unique, feature of aerospace planes is that the propulsion engines typically have no power extraction shafts, either because the propulsion engines are themselves shaftless (ramjets or scramjets), or because the core rotating parts are inaccessible (turboramjets, air turborockets).
1990-09-01
Technical Paper
901887
Karol Kerns
Research on operational use of data link technology as a means of exchanging information between aircraft and ground-based facilities has been underway for well over a decade. From this work, potentially useful data exist that remain largely unexploited for purposes of operational development. This paper reviews the simulation literature on data link communication between controllers and pilots to synthesize a base of useful, generalizable knowledge. General effects of the data link technology on the volume, speed, and timing of Air Traffic Control communications are analyzed for their operational significance. The analytic framework depicts data link effectiveness as interdependent with operational context, procedures and applications, and human interface design. Current research leaves many questions unanswered but consistently indicates that the combination of voice and data link communication outperforms either medium used by itself.
1990-09-01
Technical Paper
901888
Charles E. Knox, Charles H. Scanlon
Message exchange for air traffic control (ATC) purposes via data link offers the potential benefits of increasing the airspace system safety and efficiency. This is accomplished by reducing communication errors and relieving the overloaded ATC radio frequencies, which hamper efficient message exchanges during peak traffic periods in many busy terminal areas. However, the many uses and advantages of data link create additional questions concerning the interface among the human-users and the cockpit and ground systems. A flight test was conducted in the NASA Langley B-737 airplane to contrast flight operations using current voice communications with the use of data link for transmitting both strategic and tactical ATC clearances during a typical commercial airline flight from takeoff to landing. Commercial airplane pilots were used as test subjects.
1990-09-01
Technical Paper
901884
Michael C. Reynolds
Data link is the FAA's response to increases in air traffic communications. Data link can become a highly capable and quality tool for the National Airspace System (NAS) if a SYSTEMS CENTERED DESIGN APPROACH is taken. EVERY element must be carefully analyzed, designed and integrated as critical components of the NAS. Pilot performance in the NAS will be one of the keys to a quality system; tools must be provided that complement their experience, skills, and knowledge. The equipment must be ancillary to the pilots, not vice versa; equipment must be oriented towards solving problems without creating more or different kinds of problems.
1990-09-01
Technical Paper
901886
William H. Corwin, Hugo W. McCauley
Human factors issues related to the retrofit of data link in commercial transport aircraft are discussed. Topics that must be considered for data link implementation include, the loss of the “party line,” (i.e., the availability to all aircraft of information transmitted on a common voice frequency), and the “scheduling” of information to the flight crew. This paper focuses primarily on the human factors issues related to retrofit of Mode S. Retrofit is a difficult task because panel space accessible to flight crew members is limited. As with all cockpit equipment, data link implementation will have to comply with Federal Aviation Regulation 25.1523, which requires the manufacturer to address the conspicuity and ease of use of the data link device, and to assess the impact on crew workload.
1990-09-01
Technical Paper
901872
Jerry T. Dennis
The airline industry has yet to define a meaningful method for determining organizational fitness through internal analysis. Prior to deregulation, Airline Safety Departments and Programs were found in nearly every major and regional carrier. Today there are relatively few safety departments in comparison to pre deregulation. In addition, contemporary safety departments do not enjoy the same stature within the airlines; where department heads were formerly vice presidents, they are now directors or managers. Currently, the FAA is encouraging the industry to implement “Self Audit” programs based primarily on regulatory adherence. However, there is still no requirement or emphasis for a “Safety Department”. Additionally, there is no incentive for operators to establish a dynamic loss control or risk management program.
1990-09-01
Technical Paper
901873
Walter S. Coleman
The airlines, the Federal Aviation Administration and individual crewmembers have a shared responsibility, primarily through regulatory requirements, to ensure that the traveling public is provided with crewmembers who are fit to perform their duties.
1990-09-01
Technical Paper
901869
Robert J. Englar, David M. Schuster, Douglas A. Ford
Experimental investigations have been conducted to evaluate the aerodynamic performance and control of Unlimited-class hydroplanes racing at speeds exceeding 200 mph. These vehicles operate in very strong ground effect and may encounter unexpected disturbances such as wind gusts or waves, which can cause uncontrolled pitch-up and destruction. Specific test techniques have been developed in a modified subsonic wind tunnel to simulate these conditions, allow evaluation of the vehicle's aerodynamics and develop novel control surfaces. The paper presents details of these facilities and test techniques, associated wing-in-ground-effect tests, and characteristics of the pitching hydroplane as it transitions between in- and out-of-ground effect.