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Laminated Sidelights and Asymmetrical Windshields for Cars | This paper deals with new concepts for automotive glazing applications, with reference to weight reduction, improved security, and enhanced robustness: Laminated sidelights and asymmetrical windshields are considered. Main advantages are reviewed. Best designs are proposed considering the main functionalities of both products, particularly the mechanical properties required for automotive glazing. |
Evaluating the Intrusion Resistance of Installed Motor Vehicle Glazing | Intrusion resistant glazing increases the time and effort required to gain unauthorized entry to a motor vehicle. This paper presents the results from a series of tests designed to measure the performance of laminated intrusion resistant glazings as installed. These tests were conducted as part of a study to evaluate the performance of different polyvinyl butyral (PVB) interlayer thicknesses and adhesions for penetration resistance. Readers of this paper should gain a broad understanding of the performance of these glazings and their level of resistance. |
Interior Noise Analysis Based on Acoustic Excitation Tests at Low-Frequency Range | An experimental analysis is performed on structure-borne sound in the low-frequency range under 50 Hz by applying an acoustic excitation test to a fully trimmed vehicle. This analysis makes use of the structural-acoustic reciprocity technique in which the vibration distribution of the car body is measured while the vehicle is being acoustically excited by a loudspeaker placed at the position of a passenger's ear. This paper explains why the concept of reciprocity should be applied to the study of low-frequency structure-borne sound, and discusses the causes of road noise, a typical problem in structure-borne sound associated with passenger cars. |
Experimental Evaluation of Wind Noise Sources: A Case Study | Several of the authors have recently developed procedures to efficiently evaluate experimentally the relative contributions of various wind noise paths and sources. These procedures are described and, as a case study, results are provided for the noise in the interior of a production automobile subjected to wind tunnel airflow. The present measurements and analysis indicate that for the tested vehicle significant contributions to interior noise are provided by underbody and wheel well flows, radiation from the roof and seal aspiration. A significant tone associated with vortex shedding from the radio antenna was also noted. |
Empirical Noise Model for Power Train Noise in a Passenger Vehicle | Power train noise reaches the interior through structureborne paths and through airborne transmission of engine casing noise. To determine transfer functions from vibration to interior noise a shaker was attached at the engine attachment points, with the engine removed. A simple engine noise simulator, with loudspeaker cones on its faces, was placed in the engine compartment to measure airborne transfer functions to interior noise. Empirical noise estimates, based on the incoherent sum of contributions for individual source terms times the appropriate transfer function, compared remarkably well with measured levels obtained from dynomometer tests. Airborne transmission dominates above 1.5kHz. At lower frequencies engine casing radiation and vibration contributions are comparable. |
Analysis of Vehicle Pillar Cavity Foam Block Effect on Interior Noise Using SEA | Closed cell foam has been used for filling vehicle pillar cavities at select locations to block road noise transmitted through pillars. In the past, most pillar foam implementations in vehicle programs were driven by subjective improvements in interior sound. In this study road test results are used to correlate a detailed CAE (Computer-Aided Engineering) model based on the statistical energy analysis method. Noise reduction characteristics of pillar with a number of foam block fillings were then studied using the CAE model. The CAE models provided means to model and understand the mechanism of noise energy flow through pillar cavities. A number of insightful conclusions were obtained as result of the study. |
Perceptual Transfer Function for Automotive Sound Systems | Measurement of acoustic frequency response is extended to include aspects of speech and music perception in rooms. An apparatus is described that combines established and new techniques in a computer based measuring system. The resulting objective plot has a better correlation with subjective assessment than previous methods. The flexibility of the measurement platform encourages future development. |
All Olefinic Interiors-What Will It Take To Happen? | TPO is getting wider acceptance for automotive applications. An exterior application like a fascia is a very good example. Interiors are still a challenge due to many reasons including overall system cost. For interior applications, ?쏿ll-olefin??means it mainly consists of three materials: TPO skin, cross-linked olefinic-based foam and PP substrate. The driving force for TPO in Europe is mainly recyclability while in the USA, it is long-term durability. This paper describes the key limitations of the current TPO systems which are: poor grain retention of TPO skin, shrinkage in-consistency of the skin, high cost of priming (or other treatments) and painting of the skin, lower process window of the semi-crystalline TPO material during thermoforming or In-mold lamination / Low pressure molding, high cost of the foam, low tear strength of the foam for deep draw ratio etc. The paper shows the different ways of manufacturing the all olefinic parts which are: thermoforming over PP substrate, different Low pressure molding with in-mold lamination techniques, expanded PP foam process, slush molding etc. The limitations for each process and suggestions to overcome the disadvantages will be discussed to make all olefinic TPO interior parts viable and cost effective. The possibility of reducing the overall system cost will also be discussed such as: general information on formulation development to reduce the skin thickness for thermoforming, how to improve the properties of foam to reduce the thickness without affecting the formability and resiliency, value added recyclability of the skin/foam offal from production, and improving the paint efficiency etc. |
Frequency Domain Considerations in Vehicle Design for Optimal Structural Feel | A vehicle perceived to be solid and vibration free is said to have good ?쐓tructural feel?? Specification for vehicle design to achieve a good stuctural feel depends heavily on the management of resonant modes existing in the low frequency domain. These resonances include vehicle rigid body, chassis subsystem, body flexure and large component modes. A process to specify the placement of resonant modes in the low frequency domain is discussed. This process allocates blocks within the frequency domain for classes of resonant modes stated above. Segregation of these blocks of resonant modes in the frequency domain limits modal interaction, thereby minimizing sympathetic vibration. Additionally, known areas of human body sensitivity within this low frequency domain are stated. Lastly, known vibration inputs are identified. This process is cognizant of these inputs and avoids overlapping with the vehicle resonant modes to provide further insurance of minimal modal interaction. |
The Strategy of Accelerated Reliability Testing Development for Car Components | This paper analyzes the reasons why current accelerated reliability testing (ART) results for passenger cars often cannot give accurate information for sufficient reliability, fatigue, and durability evaluation and prediction in the field. Why does accelerated testing (AT) give often minimum benefits for companies that use it? The basic principles of strategy that can help to eliminate these reasons will be described. In order to execute this strategy the following will be shown: the full hierarchy of the car and its components in a connection and interaction with each other; how accelerated environmental testing can be improved if a simultaneous combination of basic environmental factors (temperature, humidity, pollution, radiation, etc.) will be used; how each of these factors can be simulated more accurately in the laboratory; how one can improve accelerated corrosion testing of the car components if one takes into account that it is a combination of chemical, mechanical, motion, etc. influences; how one can improve vibration testing if one takes into account that the car's vibration is complicated and acts simultaneously with the rotation of the wheels; etc. |
The Effects of Outlet Geometry on Automotive Demister Performance | The established method of clearing a misted car windshield or of maintaining a clear view under misting conditions is through the application of an air supply via jet outlets in the instrument panel. The ability of such arrangements to perform adequately is a function of the prevailing environmental conditions, the vehicle speed, the condition of the demist air source and the geometry and arrangement of the jet outlets. This paper presents experimental data obtained in a purpose built environmental chamber designed to accommodate simple rectangular jets impinging on a misted glass surface. The facility consists of three conditioned air sources applied to a test chamber designed to represent the external, internal and demist air flows. Mist conditions on the glass surface are determined using a novel technique employing a CCD camera acquiring grey scale images which are digitally analysed to generate mist detection, grading and clearing contour data. The test facility and mist analysis techniques are described. Transient jet performance is investigated in a parametric study that addresses the effects of jet aspect ratio, offset, impingement angle and mean volume flow rate on clearing performance. Results are presented in terms of parameters derived from the images recorded during the clearing process. These parameters include rate of clearing terms, breakthrough time and location of clearing centre relative to geometric impingement point. Steady state performance is presented for a number of representative geometries by examining the size of the clear area for a range of interior humidity levels. |
The Importance of Sealing Pass-Through Locations Via the Front of Dash Barrier Assembly | An improvement in a vehicle's front of dash barrier assembly's acoustical performance has in the past been addressed by both adding individual absorbers and increasing the overall weight of the dash sound barrier assembly. Depending upon the target market of the vehicle, adding mass may not be an option for improved acoustical performance. Understanding the value of an increase in vehicle mass and / or cost for a specific level of improved acoustical performance continues to plague both Original Equipment Manufacturer (OEM) Engineers and Purchasing representatives. This paper examines the importance of properly sealing the front of dash pass-through areas and offers recommendations which can improve the overall vehicle acoustical performance without the addition of cost and mass to the vehicle. It also examines how the acoustical performance of an engineering change can be determined and relates this performance to a Value Statement in an effort to assist the engineering community in judging the overall value of this engineering change. |
The Next Step in Acoustical Part Weight Reduction | Weight reduction with maintained part performance is a continuing trend throughout the automotive industry. Acoustical insulation parts (carpet underlay and dash insulators) are no exception. Several years ago, ICI Polyurethanes led the industry in establishing a molded density standard of 48 kg/m3. Although this is the current production standard, the technology drive is toward even lower weights. Recent technological demonstrations show that molded densities of 35-38 kg/m3 are achievable. In addition to removing weight, acoustical performance can be maintained with no deficiencies in physical characteristics. |
Acoustical Advantages of a New Polypropylene Absorbing Material | Sound absorption is one way to control noise in automotive passenger compartments. Fibrous or porous materials absorb sound in a cavity by dissipating energy associated with a propagating sound wave. The objective of this study was to evaluate the acoustic performance of a cotton fiber absorbing material in comparison to a new polypropylene fibrous material, called ECOSORB 짰. The acoustical evaluation was done using measurements of material properties along with sound pressure level from road testing of a fully-assembled vehicle. The new polypropylene fibrous material showed significant advantages over the cotton fiber materials in material properties testing and also in-vehicle measurements. In addition to the performance benefits, the polypropylene absorber provided weight savings over the cotton fiber material. |
Assessing the Performance of Electrically Heated Windshield | The safety and comfort aspects of passenger vehicles are significant sales argument and have become a topic of rising importance during the development process of a new vehicle. The objective of this study is to compare the performance of several current model vehicles, highlight the drawbacks of current defrosting/demisting systems and point the way to improved passive mechanisms. The investigation is experimental. The work presented is an experimental and numeric investigation of the clear-up pattern of a current vehicle fitted with an electrically heated windshield. Nottingham FDL climatic wind tunnel is used to perform the experimental tests. The clear up pattern developed utilising the vehicle defroster system is digitally captured and compared to the clear up pattern developed utilising the electrical heated windshield. Moreover, the clear up pattern developed using the vehicle defroster system is used to validate a computational model. The aim is to build a confidence on the relatively new developed numerical tools for phase change simulation. The design features of electrically heated windshields and the associated gadgets are briefly discussed. With the predicted shift to use 42V powernet, the market will require more vehicles to be installed with electrically heated windshields. The main benefit to the vehicle customer is the convenience of reducing the clear up times. |
Safety Performance of a Chemically Strengthened Windshield | Safety performance of an experimental windshield with a thin, chemically tempered inner pane is compared with the standard windshield and other experimental windshields. The chemically tempered windshield has a penetration velocity of 35 mph compared with 26 mph penetration velocity for the standard windshield and has lower peak head accelerations than other types used in the experiments. The windshield tested produces a bulge on impact, which decelerates the head over a long distance with low accelerations. The bulge or pocket is lined with particles that are less lacerative than the standard annealed glass. |
A Vibro-Acoustic Test System for Simulation of Saturn V Dynamic Launch Environment on Major Space Vehicle Structures | A description of the largest Acoustic and Vibration Test Facilities in existence for the simulation of major launch vehicle dynamic environment is given and the operational characteristics of both are discussed. Sinusoidal and random excitation techniques are described and unique vibration control methods presented. A comparison of the effects of vibration and acoustic excitation on major space vehicle structures is made. |
Causes of Significant Injuries in Nonfatal Traffic Accidents | The Vehicular Trauma Research Group of the UCLA School of Medicine is currently conducting intensive studies of selected traffic accidents. Data is presented from an analysis of the first 150 traffic accidents studied. The role of vehicular design, mechanical failure and the performance of the new 1966 windshield in injury causation are discussed and illustrative examples are presented. The importance of detailed studies of traffic accidents is stressed as a method of yielding information not readily available by other methods of study. This approach is mandatory to evaluate new and pending vehicular design modifications and may be the only method of detecting and assessing the role of mechanical failure in traffic accident causation. |
Ejection - The Leading Cause of Death in Automobile Accidents * | From on-scene investigations of 139 fatal automobile accidents during four years, it was found that of 177 persons killed, 48, or 27%, died by ejection, which is thus the leading cause of death. As would be expected, most (two-thirds) were ejected through opened doors; others were ejected through windshields, open convertible roofs, or door windows. From the investigations it is postulated that 80% of the ejection deaths would have been prevented had the ejectees worn seat belts. |
Passenger Protection from Front-End Impacts | Scientific methodology and engineering techniques were applied to a series of thirteen automobile collision experiments involving the front-end impact exposures of full-size passenger vehicles rear ending identical sedans. The purpose was to evaluate the relative protective merits of seat designs, steering columns, windshields, restraints and general interior surface design with respect to the many variables common to front-end impacts. The front-end collisions reported in this paper provide additional design data for protection of motorists from collision-injuries for the wide range of exposure speeds from 10 through 55 mph. |
Automotive Piston-Engine Noise And Its Reduction - A Literature Survey | This paper reviews the sources of externally radiated automotive piston engine and vehicle noise and describes them in detail. The effects of various design and operational characters on intensity and character of noise, noise measurement, and analysis and identifications procedures are given extensive examination. A summary of current research on the reduction of engine noise is presented. |
Basic Facts about Noise as Related to Aviation | NOISE has two aspects: (1) subjectively, it is any unwanted sound; (2) objectively, it is characterized by many variables. The subjective view is important in determining the response of people to aircraft noise and in establishing engineering design objectives for noise control. The engineering of noise control deals with the objective aspect in three parts: 1. The noise source ??characterized by its total noise power output and the distribution of this power with respect to frequency and space. 2. The path ??propagation in structures, through the air, and over terrain as influenced by properties of materials, geometry, meteorological conditions, and topography. 3. The received noise ??its sound level, frequency spectrum, time pattern, and other variables as required to correlate with the subjective response of man in the aircraft, on the line or in the community. |
Safety Glass Breakage by Motorists During Collisions | Five intersection-type collision experiments were conducted at 40 mph to provide data on several categories of collision performance. This paper presents the interactions of passenger heads with car windshields and side-glass. Instrumentation included 60 channels of force and acceleration data, supported by the photographic coverage of 40 cameras. Tri-axial accelerometers, mounted in anthropometric dummy heads and chests, and strain gauges bonded to windshields facilitated data collection on the relative collision performances of different types of safety glass. |
Accidental Motorist Ejection and Door Latching Systems | A general dissertation on the factors relating to accidental door opening, including: nomenclature, classification of the various types of loading of significance; description of five known causes of accidental door opening not associated with door latch strength; supporting evidence from full-scale collision research; photographic display of 1964 model door latches; review of the factors relating to the evaluation of door latch installation and three suggested test configurations to cover the most significant causes of accidental door opening. |
A Review of ACIR Findings | During a period of ten years, ACIR has amassed a large accident sample, drawn from a total of 28 states. Statistical analysis has aimed at (1) identification of leading injury sources and (2) statistical evaluation of car safety features. Studies show that ejection, the steering wheel, instrument panel, and the windshield are the four categories most often associated with car occupant injuries. Countermeasures include seat belts, safety door latches, recessed-hub steering wheels, and instrument panel padding. Studies have shown partial-to-substantial countermeasure effectiveness for seat belts, safety door latches, and instrument panel padding. Analysis of other safety devices is under way. |
Modern Concepts in Rapid Transit and the Use of Rubber Tires for Transit Vehicles | A resurgence of interest in rapid transit has resulted in a multiplicity of systems being proposed. Among these have been proposals to use guided rubber tired vehicles. The history and current status of development of a number of these systems is presented. The development of a new supported, dual track rubber tired system is described together with a review of operation and design considerations. Rolling resistance and acoustical factors are discussed and costs of several types of systems are compared. While rubber-tired systems are more costly than those having conventional steel wheels, special consideration of grades and community acceptance may justify their use. |
Tooling for Multiple Lead Applications of Electrical Discharge Machining | Multiple lead enables electrical discharge machining to compete as a production method with conventional machining methods, provided proper tooling is used. In this paper, the electrical discharge power supply, the machine, the work and electrode holding fixtures, the electrodes, and the dielectric are all considered as tools. Each has its individual function in obtaining an efficient EDM cut which is essential for multiple-lead operation. The power supply must be capable of producing discharges that are compatible with the electrodes and workpieces being used. Machines must furnish the servo function and auxiliary cycling equipment. Work and electrode holding fixtures must hold precision relationship between electrodes and workpieces as well as eliminate electrode vibration and direct dielectric flow. The electrodes must be suitable to the application, and because they are expendable, must be economically produced. The dielectric must be suitable to the application and must be adequately filtered and directed. |
General Approach to the FLUTTER PROBLEM | AGENERAL approach to the flutter problem is outlined, which can be used to investigate any mode of flutter of any structure provided the air-forces are known. The method can be used to investigate the possibility of flutter on such structures as airplane wings, tail surfaces, and bomb doors, aircraft propeller blades, vehicular bridges, buildings, and so on. With a well-known solution for the air-forces for two-dimensional flow over an airfoil with an aileron, equations have been derived which can be used to determine the flutter speed for the wing or tail surfaces of any conventional airplane. The use of still-air vibration tests in obtaining the structural friction of structures, and in checking a part of the flutter computations experimentally is indicated. Finally, to suggest the possibilities in the use of this method, a standardized procedure for its general application to aircraft flutter problems is outlined briefly. |
Heating, Ventilating, and Cooling of Passenger Cars | MANY question whether a complete job of air-conditioning passenger cars for all weather conditions can be done at a price which most car buyers care to pay and with assurance that dependable and acceptable results can be guaranteed, Mr. Chase reports in prefacing this paper, a comparative study of existing heating, ventilating, and cooling systems. Some 1939 and many more 1940 car models, he believes, yield greatly improved results in heating the entire car and ventilating it well with all windows closed, but, he points out, the design of such systems is still in a state of flux. Mr. Chase divides all currently available systems into four classifications for convenient discussion: (1) heating by recirculation only, ventilation incidental; (2) heating in which part of the air is recirculated and part taken from outside and can be heated before delivery; (3) heating in which all air passing through heater is taken from outside; (4) systems which include means for heating, cooling by refrigeration, and at least incidental circulation. The author describes and compares current systems in each of the classifications and comments on the problems, advantages and disadvantages involved in each of the designs. He includes also structural considerations, mentioning that, except for compressors, valves, and a few other somewhat special parts, most of the components of all these systems are produced largely from sheet metal or are die-cast in zinc alloy. |
DEFICIENCIES of CONVERTED PASSENGER AIRPLANES for CARGO TRANSPORT and OPERATING REQUIREMENTS | SHORTCOMINGS of the converted passenger plane are at least 10 in number, says Mr. Froesch, classifying them as follows: (1) floor slope and irregularity of floor at door causing concentration of load at that point; (2) floors too weak, requiring reinforcing; (3) doors too narrow for entrance of bulky loads; (4) no anchorage for load fasteners; (5) no provisions for cargo handler station; (6) hard to distribute load so as to give a satisfactory center-of-gravity location; (7) lavatory in the wrong place; (8) insufficient fire extinguisher protection; (9) door sill heights too variable; (10) circular or oval fuselage shape, which cannot be used effectively. A big problem is to get the rate down to the point where repeat business will follow. Eventually this might mean a 10 to 12짖 per mile rate under proper designing, Mr. Froesch declares. But, he says, size and capacity of the cargo plane cannot be predicted until a thorough analysis of the air express and freight market has been made. A density-volume ratio of 8 to 9 lb per cu ft can be used, Mr. Froesch says, as a design criterion in figuring size of compartment. He points out heating and ventilation aspects of the cargo compartment and explains desirability of having a small compartment for protection of valuables close to the cockpit. The airplane should also be designed so that preventive maintenance and service methods can be best applied. |
Passenger-Car Road Noise | THE authors introduce their paper by outlining the various sources of noise existing in the motor car, together with some of the suppression means. Noise measurement, test methods, and the mechanism of the transmission of forces generated by the contact between the tire and the road to the body and frame are discussed. The authors state that, since these forces produce motion and deflection of the body, they are responsible for the road noise, and conclude that the proper approach to a method for suppressing road noise is through the structural design of the vehicle. They suggest, in the main, the localizing of stress to stress members, the raising of the resonant frequencies of the structure, the detuning of the suspension system, the body, and the frame, together with some isolation at selected points. |
What Motor Cars Can Be | FUTURE motor-car development, Mr. Stout contends, will follow the functional art of bus and airplane development rather than motor-car precedents. The interior instead of the exterior, he believes, is the basic thing to be studied, pointing out that passenger room has been growing less and less. The car of the future, therefore, he predicts, will have an interior that extends out the full width of the car with no running boards, will have totally enclosed wheels, will have a unit frame and body, the engine in the rear, and either double or sliding doors. The effect of rear-engine construction on ride, bounce control, braking, and traction on muddy and icy roads is explained. New body materials, such as plastics, are looked for on future cars to insulate them from the radiant heat of the sun, especially for roofs. Mr. Stout sees light-weight air-cooled engines in future cars, weighing not over 3쩍 lb per hp. The possibilities of rubber springs are discussed. |
WOOD FOR AUTOMOBILE BODIES 1 | Shortage of the most desirable kinds of wood for automobile-body purposes has necessitated the substitution of second-choice woods having the essential required properties and the buying of stock for body parts in cut-up dimensions that conform in size with those now produced in the cutting-room. An investigation by the United States Forest Products Laboratory as to the species, kinds, grades, sizes and amounts used by the automotive industry shows that maple and elm comprise over one-half the total amount used and that ash and gum constitute one-half of the remainder. Although the quantity of ash used has not decreased, the increase in the production of medium and low-priced cars in the last few years bas caused a proportional increase in the demand for maple and elm. Classifying cars for purposes of analysis into four groups, small, medium, medium-large and large, the investigators found that the woods most used in small cars are hard and soft maple, elm, birch, beech, oak, gum and pine; that maple, elm and birch are used extensively in bodies of the medium and medium-large classes; and that ash predominates in the large cars, with hard maple as an alternative choice. Fifty-one per cent of the running-boards are made of pine, and 17 per cent are made of sound wormy oak. Oak, ash and elm are used for top-bows in the proportion of 92, 7 and 1. The grade of lumber used in bodies is very high, 40 per cent being firsts and seconds, and 49 per cent No. 1 common and selects. The problem of eliminating light or brash ash is important and, while there are no visual means by which tough and brash ash can be separated, the factors that afford a fairly reliable criterion of strength and toughness are density, rate of growth, proportion of summerwood and the original position of the wood in the tree. Seasoned ash that has good weight and is sound will have strength. Unseasoned ash, on the other hand, cannot be judged by weight. Little or no uniformity in size of corresponding parts was found among the various makes of body, although the majority fall within very narrow limits. Charts have been prepared showing the range and grouping of the sizes of several of the main body parts, such as the body and door pillars of closed bodies, the main side sills, the side roof-rails, the front and rear roof-rails and the rear belt-rails. The stock used in the larger bodies is of very high quality; in open bodies a few small defects are allowed; in smaller and lighter bodies the requirements are not so severe, a mixture of woods is used, and some defects, such as small sound knots, are allowed; in soft maple, elm and gum, considerable amounts of stain and dote are admitted. When the requirements are not exacting it would be possible to utilize sound low-grades; the use of clear stock where sound stock is sufficient introduces unwarranted expense and wastes material that might serve higher purposes. As the waste in cutting ranges from 20 to 50 per cent, it is evident that careful work at the saws may result in considerable saving. Other ways in which saving may be effected are the gluing-up of stock to get required sizes and a more general use of ready-cut small-dimension stock. As automobile builders are much interested in finding woods that may be substituted for those now in use, a table is given showing the specific gravity, strength, stiffness, shock-resisting ability and hardness of the principal species as compared with those of forest-grown white ash; and the advantages and disadvantages of first and second-growth timber, and such woods as ash, hard and soft maple, rock and white elm, birch, red and sap gum, oak and the softwoods are discussed. |
GLIMPSES OF BALLOON-TIRE PROGRESS | The balloon tire has run the gauntlet of skepticism and credulity and has received scientific and popular approval from engineers and car-owners. The reasons for its acceptance are satisfactory appearance, practicability and transportation comfort. Tire and rim sizes, masquerading for years under wrong dimensional markings, have caused immeasurable inconvenience. This condition resulted from poor standards or entire lack of standards supervision. A committee with backbone is needed to fix and to maintain standards. Rapid balloon-tire tread-wear depends on tread profile, pressure and movement. Increased inflation-pressure and a scientifically designed tread will reduce the rapidity of this wear. Tread-contact areas and pressures are pictured to explain the advantages of a properly designed tread, and to demonstrate that the casing carries an appreciable part of the tire load. Tread configuration should assure traction, flexibility, easy steering, and good wear and should be not too rugged. Tread surface should be largely non-skid for best all-year and all-highway service. The public is confused by diverse balloon-tire inflation-pressure tables offered by tire and vehicle makers. One standard table can and should be adopted for all balloon tires. Increasing the number of plies in a balloon tire increases the ease of entry of a puncturing object into the tread, but decreases the probability of complete penetration and actual deflation from puncture. Gradual loss of air from tires is due chiefly to diffusion through the tube rubber. The rate depends on daily mileage, road conditions and tube quality and thickness. Average diffusion amounts to from 1 to 5 lb. per week. Volume of noise in closed cars is no greater with balloon tires than with high-pressure tires, as indicated by audiometer measurements. Different cars show important differences in noise volume, due principally to differences in engines. Balloon tires are not a fundamental cause of shimmying. Improper balance between front-end units appears to offer the chief cause. There is no common remedy. More original and thorough research by experts in their particular fields is urged so that America will lead in the refinement as well as in the production of tires and automobiles. |
PYROXYLIN ENAMEL OVERCOMES FINISH FAILURES | Public demand for more durability in automobile finishes has led to new developments in finishing materials and methods through cooperation of finishing materials manufacturers and automobile builders. By experimentation it has been found that certain cellulose nitrate materials, when applied over suitable under-coats, dry quickly in the air by evaporation of the solvents and leave a film that is hard and tough. Its durability is many times greater than that of the most durable finishing-varnish and, as it has been discovered that sufficient luster can be produced by rubbing and polishing the unprotected cellulose-nitrate surface, one of the large automobile production plants adopted, in July, 1923, as its standard method of finishing, the use of such a finishing coat over primer and surfacer coats, obtaining the luster by polishing the cellulose-nitrate top-coat. A number of companies have now adopted this process. Certain finishing-material companies, having discovered how to increase the quantity of cellulose-nitrate in solution without increasing the viscosity, made possible its use for automobile finishing. The change from a varnish to a pyroxylin finishing-system seems simple but a cellulose-nitrate finishing-material is complex. A large number of gums and oils can be used to obtain the desired properties but considerable study is required to determine the kinds and the quantities to use. The softeners and the stabilizers may be part of the solvents but they have their own duties to perform. The solvents hold the cellulose nitrate in solution and their evaporation permits the film to be deposited and harden. The nature of the solvents greatly influences the character of the film. Not all pyroxylin materials have great durability. This is obtained only by using the proper basic materials, combined in the right proportion and applied in the correct way. The fundamental cause of the failure of finishes is the contraction of the top material while the underlying material is still moist. During exposure to rain or other dampness out of doors, the entire film absorbs moisture, swells and softens. When the sun comes out, the outer surface dries and contracts and, if the material is not sufficiently elastic to withstand the stresses, cracks develop. Durability can be increased by reducing the severity of these factors. By nature, the pyroxylin film is much less absorbent than the varnish film and the particles of pigment shade the materials beneath so that only the extreme outer surface is exposed to the sunlight. In time, the moisture and sunlight do, however, cause a type of failure known as ?쐁halking.??This effect is of such microscopic depth that it can be removed easily by washing with a mild abrasive or by polishing, thereby exposing a fresh surface, and in the case of a good cellulose-nitrate finish the washing or polishing can be repeated many times before any serious wearing away of the surface occurs. By mild polishing every few weeks, together with ordinary cleaning of the car, the finish can be kept with an appearance as good as it had on the showroom floor. The author describes the fundamental operations in finishing an automobile body with paints and varnishes, explaining the purposes of the different coatings and the filling and rubbing, and classifies the successive coatings in all finishing systems as (a) primer, (b) surfacer, (c) color and rubbing, and (d) finishing. To determine the cause of the rapid failure of finishes, test panels were exposed to the weather during different periods of the year and it was found that the length of life of varnishes depends greatly upon the season, varying with the amount of sunlight and heat, being shortest in summer and longest in winter. These tests also showed that the primer and surfacer coats were very durable but that the color and rubbing varnishes were of low durability, failing in from 1 to 5 weeks when unprotected by finishing varnish. The real reason for the short life of the ordinary automobile-finish was discovered to be the failure of the color and rubbing varnishes, which crack and take the finishing varnish with them. However, the finishing varnish is itself partially responsible for the failure of the color and the rubbing coats, because its film is easily scratched by grit and cleaning or by other mechanical injury, and failure of the underlying coat starts at these unprotected spots. The life of a varnish surface is shortened by regular polishing even if it is washed regularly only with water. A polish that is as nearly harmless as any is made of linseed oil mixed with enough turpentine to prevent the application of too heavy a film of oil. The life of ordinary production varnish-finishes can be doubled or quadrupled by the use of color and rubbing varnishes of high durability but they require a long time for air-drying and forced drying is likely to injure the color. |
HEADLIGHTS | Two points are cited as illustrating the difficulty of enforcing the present regulations, namely, (a) the variation in the angle of the headlight beam caused by the compression of the springs when the loading of the car is changed from no load to full load and (b) the variation of the tilting of the beam caused by the pitching of the car on an ordinary road, the effect being similar to that produced by flashes of lightning in a pitch-dark night. Denial is made of the author's alleged advocacy of diffused lighting and comparison is made of the distribution-curves obtained with frosted bulbs and those obtained with fairly good lamps conforming to the Society's specifications. Attention is called to three points in this comparison: (a) the light from the frosted bulb along the horizontal is only about 50 per cent of that available with a lamp conforming to the Society's specification, (b) the foot-candle illumination measured perpendicularly to the beam at various points on the surface of a level road is much less with the frosted bulb than with the lamp of the Society's specification, how much harm a bright illumination immediately in front of the car interferes with acuity of vision is a subject for additional research and (c) the light from the frosted bulb does not change appreciably for any angle through which the chassis is likely to move as a result of road shocks; consequently, when the frosted bulb is used, road shocks and spring vibration do not affect the eyes of an approaching driver. Sharp cut-off above the horizontal is considered in-advisable. The possibilities of non-symmetrical lighting, the author believes, are worth considering, and the results of some experiments are detailed. He expresses a preference for the use of two diffused lights as regular equipment and of a third lamp, adjusted according to the Society's specifications, so that the maximum candlepower would be horizontal. Reference is made to the test target in use by the Royal Automobile Club and to the results of tests made with it, but this method is said to be objectionable as a basis of specifications because it is tedious and the results depend largely upon the condition of the observer's eyes. Although measurements of all the imaginable functions of the human eye have apparently been made, such tests should be repeated under automobile-lighting conditions, for factors that previously may have been neglected in tests frequently become important when the conditions are changed. As the normal eye requires nearly 1 sec. to adjust itself to radically changed conditions of illumination, this period is dangerously long when a car is running at high speed. |
Automobile Bodies, from the Abstract Customer's Viewpoint | CONSTRUCTIVE criticism of automobile bodies as now built is given herein, based on experience gained in driving five-passenger sedan cars of many makes a total distance of nearly 10,000,000 miles in one year in tests at the General Motors Proving Ground. The fault finding, although humorously exaggerated, will be valuable if taken seriously, as it gives to all body designers and builders the benefit of testing experience that few companies are in a position to gain at first hand. The author treats his subject from the viewpoint of the abstract customer; that is, the automobile-purchasing public as a whole and as represened by the imaginary average man, who is assumed to have average stature and body structure and to drive all the different makes of car. Thus he is assumed to change from one to another make frequently, instead of becoming used to only one or two cars. Factors that influence the initial and the repeated purchase of a car are given in the order of their importance, and the index by which the customer measures the merit of the car is said to be the maximum satisfaction he has experienced with each individual characteristic in all the other cars he has driven. In other words, the best in all cars is his basis of comparison of the individual car and body, and he can be completely satisfied only if one car is as good in every respect as the best that has been found in any car for that particular feature. Standardization of fundamental dimensions based on the measurements of the average figure of all drivers is indicated as a need of primary importance. Strictures are laid on various bodies because of interference with vision in front and through the rear window, because of squeaks and rattles and many other details that, because they are constantly evident to eye or ear, are more annoying than faults of the chassis. No attempt is made, however, to set up specifications for a body that will give complete satisfaction to various classes of user. |
DAMPING IN SUSPENSIONS | THE various types of damping present in vehicle suspensions and their effect on the ride are discussed by Mr. O'Connor, who compares the characteristics of the various types of damping with the mathematically adaptable viscous damping. The ideal damper and the present-day practical approach are considered. The discussion is maintained on a nonmathematical plane throughout, as the author believes that the mathematics of vibration theory is ably covered in numerous texts on the subject. |
Stress Testing Methods in Body Structures | SINCE theoretical and empirical engineering formulas do not always apply to automobile body structure, reliance must be put on structural testing to supplement available information. In this paper the author presents a technique for complete car structural and road testing in conjunction with body tests for such purposes as: 1. Aiding development of experimental body designs. 2. Assisting in the standardization of quality control methods. 3. Solving special problems in fabrication. 4. Furthering the improvement of body-frame unit structural efficiency. 5. Investigating the use of new materials. 6. Determining safety factor of body. The search for adequate methods of determining the safety factor led to the development of the roll-over test. It is accomplished by towing a car so that the wheels on one side go up a ramp at a 15-deg angle, and at a speed of 50 mph. The car is rolled in such a manner that the windshield header receives the greatest impact. |
INSTRUMENTATION OF VIBRATION IN AN AUTOMOBILE BODY | A short movie will be shown indicating the cars being tested for shake on the road and in the laboratory, and some of the equipment will be seen in operation. Next, eight slides will be shown and a detailed description will be made of each slide. The major context will be to show: 1. The functional arrangement of the equipment. 2. The method of interpreting the data for a single point under shake conditions. 3. The method of obtaining curves for multiple point studies. 4. The solution for a general problem. |
TRENDS IN MODERN AIRCRAFT STRUCTURAL DESIGN | Although the Electra structure is based on past good practice, its higher performance and use of prop-jet engines have injected certain new situations of interest to structural engineers. Such items include the new CAA gust criteria, loads created by prop-jet engine failure, development of the ?쏯o-Hazard??windshield, engine nacelle design loads, wing loads when taxiing with full wing fuel, fail safe and fatigue, the use of large die forgings, and the bleed air duct system used for de-icing. |
PRINCIPLES OF NOISE REDUCTION | THIS paper explains a few of the basic principles of the character of sound and the mechanism of human hearing. The author describes some simple experiments which demonstrate the relationship between intensity and loudness and the nature of harmony. He also points out the difficulties of accurately analyzing sound electronically, and the resulting importance of combining the finest electronic equipment with sharp, attentive human faculties. Five basic ways to reduce noise and the mechanics of each are described. The effect of these methods on the work of the sound engineer is indicated. |
Acoustic Design and Performance of Turbojet Test Facilities | THE high noise level associated with turbojet testing creates two noise problems: 1. The reduction of noise in the neighborhood of the installation to an acceptable level. 2. The protection of operating personnel from excessive noise. Desirable sound levels are established and, on the basis of these levels, specifications are written for the acoustic treatment of the turbojet facilities. The acoustic treatment must not only be satisfactory from the point of view of noise reduction, but it must also be able to withstand the very rigorous operating conditions. High-temperature and high-velocity flow of gases through the exhaust stack makes for these rigorous conditions. Designs which meet these specifications are discussed in this paper, together with performance data obtained on these designs. |
Human Problems in Jet Air Transportation | THE human problem with jet aircraft begins even before take-off, the author points out, with discomfort and loss of efficiency from noise, and ground injuries on the field or in repair shops. In the air, although noise and vibration in the jet plane are less than with the reciprocating engine, human tolerance is matched against other extreme forces of acceleration, direction changes, temperature and pressure variations. Through detailed examination of what happens to passengers and crew in the many situations that can arise to challenge human limitations, the author shows why he believes there is need for closer cooperation between the biologist and the engineer, and for better education of crewmen in the effective use of their equipment and in their own physical limitations. |
SOUND and FUROR THE JET NOISE SUPPRESSION AGE | BEFORE an evaluation of suppressors can be made or before a sensible discussion of suppression goals can be carried on, terms, conditions, and possibilities must be understood. A five-number system for evaluating suppressors is proposed. Methods of jet noise suppression undergoing general development today include frequency shifting, jet spreading, and jet velocity reduction. Basic types of jet spreaders and velocity reducers are shown and ratings given. Combinations of types have resulted in increased suppression in many instances. |
Automobile Body Loads | SINCE passenger-car bodies cannot practically be designed to meet the abnormal stresses of collision, normally needed rigidity is a major design criterion for the modern body. Bodies must be stiff enough, the author points out, not to respond easily to the excitation caused by vibration of the unsprung mass of wheels and suspensions, but not too stiff to ride comfortably. Recent trends toward more glass area and lower body height have increased the importance of determining body loads and structural requirements. Discussed here are some of the ways in which these factors are investigated, and the results which have been achieved. |
LIGHTING THE MOTORBUS | General considerations that affect the attainment of adequate lighting are mentioned, it being stated that proper lighting of the interior of a motorbus is influenced by limitations peculiar to the service, such as vibration, scant headroom, a restricted energy supply and relatively large voltage-variations. Available types of bus-lighting equipment are analyzed as to their suitability, from six different standpoints that are stated. ?쏥lare??is defined and means of obviating it are suggested, inclusive of a discussion of desirable types of finish for the interior with regard to reflecting surfaces. The severe vibration produced by many motorbuses demands head-lamps of more rugged construction than that used for the headlighting of private cars. Eight essentials for motorbus head-lamps are specified. A very large percentage of the glare and poor illumination of the motor vehicles on the roads results from improper adjustment or the lack of any means for adjustment of the head-lamps. Tail-lamps, stop and direction signals, step-lamps, trouble-lamps, lights for the signs and marker-lights are discussed. Standard incandescent lamps are recommended for use. The most suitable type of electrical system for motorbus service is outlined briefly, consideration being given to the wiring needed to minimize voltage-drop, switches, lamp sockets, fuses, generator and voltage regulator. |
The Satellite Airport System and the Community | This paper presents an answer to the ground barrier problem. Studies have defined problems in the following areas: maximum terminal capacity, internal roadway systems, automobile parking, freeways and access roads, airfreight, and noise. To find solutions to the above problems, a satellite system of airports has been developed which will smooth out the interfaces with all other forms of transportation for people and commodities, and will disperse the volumes entering the system. In our satellite airport system studies, the Metroport, with short elevated runways capable of handling the new vertical and short take-off aircraft, has evolved. An elevated rail, and in some cases a subway system, travelling clear of ground congestion will be a vital link in the transportation network. The Los Angeles satellite airport concept is one of the best answers to bringing air transportation to all sections of the metropolitan areas. |
Canada's Role in the Second Decade of the Space Age ??Inner Space Supersonics | This paper, presented to all types of Canadian engineers, has as its objective the stimulation of their interest in the many problems yet unsolved in the aviation industry. The paper describes briefly the SST programs - the British/French ?쏞oncorde,??theUnitedStates ?쏝oeing2707??andtheU.S.S.R. ?쏷U-144.??Then various engineering problems such as sonic boom, sideline noise during takeoff, cosmic rays, fuel consumption, reliability, and airport requirements, are considered. Finally, ways to reduce ground time are examined. |
Passenger Car Ventilation by Design | Favorable ventilating systems in passenger cars and their influence on the rate of air flow in the passenger compartment are shown. One example shows the pressure distribution along the centerline of the body and the differences in the pressure between possible body air inlets and outlets which determine the rate of air flow with any particular ventilation system. Several ventilating methods are shown which satisfy the requirements of increased air flow, reduced noise level and defined air flow in passenger compartment, prevention of water entry, and elimination of drafts. In view of the increasing desire for a reduction of noise level inside the passenger compartment, the noise created by the wind when the windows are opened or when the doors and windows are insufficiently sealed should be eliminated by specific ventilation openings. |
Preliminary Studies of a Supersonic Business Jet | This paper discusses two possible designs, an unswept trapezoidal wing model and an essentially delta wing model for a 10 passenger Mach 2.2 Supersonic Business Jet. The studies are quite preliminary in nature and the result of team efforts in two different Senior Aerospace Vehicle Design courses at the Georgia Institute of Technology. The philosophy of the course and the selection of this particular aircraft as a project design are touched upon briefly. The body of the paper compares the two designs, and discusses in an elementary manner their aerodynamic performance, engines, and propulsion systems; some of the design details; cost; and probable noise level, including the sonic boom problem. They are not considered solution aircraft, but the designs are believed to be fairly representative of what the resulting aircraft would resemble. The work is continuing through re-cycling and optimization of the performance by computer techniques. |
Effects of The Super Sixty Series DC-8 on Airport Requirements | A welcome relief to airport runway, taxiway, gate position saturation, and air traffic congestion is offered by the new Super Sixty Series DC-8, which now carries twice as many passengers per flight. Airplane operators benefit from substantially lower direct operating costs per seat-mile and more efficient utilization of pilot manpower in an area of growing shortage. These airplanes have a special family of problems in common with earlier jets, including community annoyance caused by noise, runway strength limitations, and the requirement for an increase in terminal people and bag gage handling equipment. |
Design, Manufacture and Marketing of Cabs for Industrial and Agricultural Equipment | This paper reviews what has happened in the cab industry since earliest developments and defines the ?쐓tate-of-the-art??at the present time, pointing out areas of design, engineering, and marketing that should be investigated. Some of the new developments in cab design such as pressurization for dust elimination, air conditioning, and noise abatement are discussed. |
Automatic Light Aircraft Readiness Monitor | A study has been made of the feasibility of performing maintenance inspections on Army aircraft using automatic electrical methods. Sensing devices discussed are for vibration, temperature, pressure, liquid levels, interlocks, chip detectors, and engine speed. Evaluation of tests show that much work needs to be accomplished before electrical inspection is practically feasable. |
Evaluation of Automobile Body Design | The automobile body is a total environment. An evaluation of this environment should include consideration of: seats, vision, noise level, heating system, ease of entry, ease of maintenance, instrumentation, trunk space, exterior, and styling. These points and others are reported in an annual survey made by Popular Mechanics magazine. The owners' report is sent to drivers all over the country who evaluate their new cars on the basis of likes and dislikes. The tabulated results can be a guide of the engineer and stylist alike. |
Delivering the Mail with Diesels - The Post Office Department Looks at Diesel Engines | To determine to what extent diesel power should be introduced into the 60,000 truck postal fleet, a comprehensive evaluation-type study was undertaken by the Automotive Division of the Post Office Department. The study encompassed the complete range of truck sizes from the large 65,000 gcw tractor-trucks to the small 1/4-ton three wheel scooters. Considered in the evaluation were such factors as reliability, noise level, driver reaction and vehicle performance characteristics, in addition to the usual comparison of fuel consumption. Although the complete life cycle of the representative gasoline and diesel vehicles being studied is not complete, certain interim findings concerning vehicle performance and driver acceptance do support the trend to more general use of diesel powered vehicles. |
Sonic Boom Problems And Noise from High Performance Propulsion Systems | The development of aircraft noise consciousness in its relation to the environments of persons in the airplane and on the ground is discussed. Measures to control aircraft noise in both connections are presented. The significance of environmental noise in the development of the supersonic commercial transport is considered. |
Recommended Practices for Use in the Measurement and Evaluation of Aircraft Neighborhood Noise Levels | SAE Committee A-21, Aircraft Exterior Noise Measurements, was formed in 1961 to develop recommended practices for use in the evaluation of aircraft noise as it relates to airport neighborhood annoyance problems. The general areas of interest to the committee include the measurement, propagation, prediction and subjective rating of aircraft noise. This paper discusses the evaluation of aircraft neighborhood noise levels and describes the subjective measures by which comparisons can be made. Included in the discussion are the recommended practices adopted by SAE and those that are being studied by Committee A-21. |
RESILIENT MOUNTINGS for Passenger-Car Powerplants | THIS paper discusses the application of resilient mountings to passenger-car powerplants. Resilient mountings have a threefold purpose: 1. They isolate engine vibration and torque impulses from the rest of the vehicle. 2. They insulate the engine mass from incoming excitations due to road irregularities. 3. Nos. 1 and 2 must be accomplished without allowing the powerplant mass to get into synchronous vibration with any component of the vehicle. |
Conditions of the Perfect Windshield * | This paper deals with the question of how windshields must be constructed and installed in order to provide the highest degree of protection for passengers in a crash. Material characteristics and mounting methods of laminated safety glass are discussed from the viewpoint of actual conditions (internal automobile dimensions and possible head-to-glass impact velocity) and concrete performance data are given. A test specification is also proposed. |
Manned Spacecraft Structure Versus Unmanned Spacecraft Structure | The large difference between the total numbers of manned and unmanned spacecraft and their respective missions is discussed. The environmental and functional requirements having different effects on the two spacecraft types are described. The materials characteristics involved in those requirements and the resulting typical configurations are reviewed. It is concluded that vibration and pressurized gas containment have the outstanding influence on spacecraft structural systems. It is noted that new structural factors of safety have not been derived on the basis of any rational consideration of the design conditions for stability or pressure critical structure. |
Moisture Protection of Window Lift Motors | This is an evaluation and description of the methods and materials used to moisture proof window lift motors as applied inside automotive doors. An environmental test cabinet is described. The materials and methods were tested for their ability to seal, their resistance to abuse, their application to the motor housing, their resistance to lubrication, and their cost. The methods of moisture protection investigated were: drain holes, moisture proofing materials, and positioning. Considering all aspects, gasket seals between the motor frame and the housing proved to be a superior way to protect motors from water damage. |
United States Supersonic Transport Development Program - Sonic Boom and Noise Research | Performance objectives for the United States supersonic transport airplane provide for minimum sonic boom levels, and engine noise levels no greater than generated by current large subsonic jet aircraft. A national program of sonic boom research has been pursued by the NASA, DOD, and FAA. A National Academy of Sciences committee is now providing guidance and counsel for this effort. Major recent sonic boom flight research programs, which have yielded extensive data, were the study of public reaction to sonic boom in the Oklahoma City area last year and the structural response program recently concluded at the White Sands Missile Range, New Mexico. Findings in these two sonic boom programs are presented. Engine noise, which has received attention since the inception of supersonic transport research and under design contracts, may be less for the SST than for current large subsonic jets under most conditions. A discussion of this subject is presented. |
Road Noise Control for a Car with a Tray Construction on Chassis | This paper describes experiments to find the source of the road noise in automobiles and methods for correcting it. To find the major source of road noise, the time lag of the sound waves was measured. Characteristics of a tray frame construction car were found by comparing the vibration modes of its frame with those of body-frame and unit construction cars. As a result of experiments, it was found that the tray frame construction car combines desirable features of both body-frame and unit construction cars. |
AUTOMOBILE FINISHING-VARNISH | Annual Meeting and Detroit Section Paper - As the success or failure of the finish of an automobile depends largely on the finishing-varnish, a plea is made for more scientific analyses of the problems of automobile finishing and more care in selecting and applying a suitable varnish. The qualities to be desired in a finishing-varnish are divided into two classes: the shop qualities and the service qualities. The shop qualities include color, body or viscosity, working, flowing, setting, hardening, fullness and the safety of working. The service qualities, or those that enable the varnish to withstand the various conditions of use, include resistance to break-down under the chemical action of the actinic rays of sunlight, to the destructive action of moisture and the alkalis in mud and soap, to expansion and contraction, to vibration and to abrasion. The three most important factors in estimating the service-giving qualities of varnish are said to be elasticity, moisture-resistance and the film factor. Each of the various terms mentioned is carefully defined, analyzed and explained. Among the constants that must be determined, either for checking uniformity or for use as bases of tests, are the non-volatile content, which is the starting-point in the test for elasticity and in computing the film factor, or thickness of the dried film; the ash, the flash-point and the acid number. An empirical formula is derived by which the thickness of the dried film can be estimated with accuracy; and in a series of appendices the details are given concerning tests for the drying, the safety of working, non-volatile content, ash, flash-point and acid number; the Kauri reduction test; and tests for moisture and alkali resistance. |
SPRING-MOVEMENT AND VIBRATION STUDY OF CARS IN ACTION | Previous efforts to obtain comfortable riding-qualities for passenger-carrying automobiles are mentioned, and a device that combines a recording seismograph and a spring-action recorder is illustrated and described, since such a device is essential in conducting investigations of this character. Methods governing the use of the device when studying spring action and chassis vibration are outlined, and the results obtained are presented graphically and discussed. Several unique features characterize these tests and are worthy of consideration, not only because of the results obtained thereby but as being good illustrations of what can be accomplished by substituting unusual and perhaps spectacular methods in special instances for ordinary practice that has failed to produce some desired result. |
The Chassisless or Unit-Car Question | THE experience gained over a period of many years in the development of light-weight, high-strength structures is now finding its way into the bus industry. Investigation of present-day bus operations showed the need for a road vehicle that would carry the greatest possible payload of passengers with a smaller horsepower engine without dragging along a load of dead weight and useless structure that would eat up gasoline instead of miles. A motor coach is now available in which are incorporated aircraft materials, design, and construction features resulting in a vehicle that is approximately 1000 lb. lighter than the lightest conventional design with the same engine horsepower and seating accommodations. Motor-bus operators today can reduce costs by the use of light-weight equipment provided there is no sacrifice of strength and reliability. They must also meet the ever-increasing demands of the public for quietness, comfort, absence of vibration and engine odors - all of which can be accomplished by placing the engine in the rear which automatically gives a better distribution of weight than has heretofore been possible with the front-engine design. |
Cab-Over-Engine Trucks - Their Status and Advance in Design | DEPENDING upon the location of the front wheel, the door and step are placed either at the front or back of the cab. Some designs incorporate a protruding ?쐆ood??portion, whereas others extend the cab fully forward. The engine compartment is either immediately back of the radiator or under the cross seat. The floor and seat heights are relatively higher than in the conventional truck, and better visibility is obtained. The engine hood is well insulated for heat and sometimes for sound as well. Most powerplants are removable readily for major repairs although, in most instances, major maintenance operations can be done readily within the cab. Front axle treads have been increased in order to give greater stability on the road as well as to avoid an excessively large wheelhouse. The change in weight distribution has called for considerably more study on braking distribution. The shortened wheelbase requires a more accurate location of the fifth wheel in tractor-semi-trailer service; has emphasized the importance of the steering-angle conditions of the front axle; and has brought riding qualities to the fore. Specifications and dimensional data accompany the paper, as well as drawings of typical layouts showing the cab, engine, and front-axle relationships. |
AUTOMOBILE BODY DESIGN | The author first considers the style and arrangement of the seats, the position of the rear axle as affecting the rear kick-up in the chassis frame, and the position of the rear wheels as determining the distance from the back of the front seat to a point where the curve of the rear fender cuts across the top edge of the chassis frame. The location of the driver's seat and of the steering-wheel are next considered, the discussion then passing to the requirements that affect the height of the body, the width of the rear seat, and the general shape. The evolution of the windshield is reviewed and present practice stated. Structural changes are then considered in relation to the artistic requirements, as regards the various effects obtained by varying the size or location of such details as windows, doors, moldings, panels, pillars, belt lines, etc., and the general lines necessary to produce an effect in keeping with the character of the car. The design of the wings or fenders, the weight, producing effects of light construction, and the use of aluminum are also considered, the conclusion reached being that the design of the highest type of automobile body should always be based primarily upon a high degree of practicability. |
Automobile Engineering Progress | GENERAL DESIGN and detail mechanical developments that have been made in the last year and incorporated in automobile, truck and motorcoach models for 1932 are reviewed by the author, who also points out noticeable trends in a number of directions. He deals in order with the cars as a whole and with each major component, from the powerplant to the tires and body, as found in many leading makes. Decision of the industry not to announce the details of new models until the end of the year, at or immediately before the opening of the New York Automobile Show in January, interfered with the presentation at this time of a complete picture of all the improvements made in American motor-vehicles, but enough information is believed to be given to show the more important developments and the ways in which the automotive engineers have responded to the desire of the times for greater refinement and efficiency in automobiles. The improvements are reflected in better appearance; greater comfort; reduction of air resistance, noise and weight; insulation against heat from the engine; easier control; improved visibility; longer service life of some parts; avoidance of vapor lock; enhanced safety; increased operating economy; and simplified servicing in some cases. |
The Aircraft Trend in Body Design from the Aircraft Viewpoint | AIRCRAFT have taken more from automobile design than they have given, but they can now repay much of the obligation without necessarily transgressing the requirements of production economy and reasonable design stability. Some of these possibilities are: (1) Improved streamlining of necessary exposed parts, particularly underneath, and incorporation of other accessories in the general body lines. (2) Use of curved glass in the windshield and lightening of all window material. (3) Reduction of the frame to the status of an assembly unit, with structural significance only in combination with the body. (4) More effective distribution of flange material around the doors. (5) Lightening of skin by use of internal stiffeners, particularly on top. (6) Development of a smaller, more efficient radiator and lightening of various engine parts. Most important is the mental attitude behind the work. Phenomenal production economy has been attained because almost every man in the industry has concentrated on it. Worthwhile weight and drag reduction would result if even one competent man were assigned specifically to that duty. Lightening, with streamlining, is a beneficent cycle that permits still further lightening, resulting directly in substantial operating economies and, indirectly, in lower production cost. |
New Technique for Noise Reduction | GREAT simplification of understanding and unusual results in production often follow new approaches to old problems. When noise problems are stated in terms of the familiar physical units of pressure, velocity, weight, and stiffness, basic ideas are obtained which can be applied directly to practice. In this way, most of the mysteries and the contradictions of noise problems are eliminated. In their elements, noise problems involve only simple physical factors which are understood easily, and which can be measured with available equipment. Similarly, the solutions involve the straightforward application of known and definite engineering principles. Although simple in their elements, most practical noise problems are very complex because of their combinations. Often much ingenuity is required to measure the physical characteristics of the noise which determine the human impressions obtained from it. Such determinations can be made by proper modification of the attack and the measuring equipment, and are the key to successful noise reduction. This paper gives a classification of the various means of quieting, and outlines the technique of applying them to production. The viewpoint is quite different from that usually employed, and the practicability of the method is illustrated by examples of actual jobs. |
A Designer-Manufacturer Viewpoint of Transport-Aircraft Needs | ONE of the most essential points in the development of any airplane is the necessity for complete cooperation between the operator and the contractor in regard to necessary and desirable features to be incorporated, and this is particularly important for a commercial-transport airplane. This coordination was carried through to a remarkably efficient culmination in the development of the Douglas transport for T.W.A. Points discussed include arrangement of cabin and cockpit, seating facilities, upholstery, elimination of vibration, heating and ventilating, soundproofing, toilet facilities, lighting, vision and maintenance. The care with which all these practical considerations were worked out is discussed, and special emphasis is laid on the important points of soundproofing and maintenance in which a remarkable degree of perfection has been attained. This care and attention to details is well worthwhile and only in this manner can a really successful transport be designed incorporating all the technical and practical knowledge of the operator, manufacturer and other specialists who assist in perfecting the various installations. |
Relation of Headlamp Construction to Headlamp Roadway-Performance | HEADLAMP construction is presented in summarized form, twelve needful factors being stated by the authors. Accelerated mechanical tests, which are designed to give within a few days results of what may be expected to take place after several years of road service, are conducted in the Headlight Laboratory of the University of California. These are described and illustrated under the headings: Vibration, durability, moisture, dust and electrical insulation, and the results are stated. A few correlation tests are commented upon. Headlamp vibration is treated at length, together with an analysis of headlamp vibration-characteristics, and a differentiation is made between vibration due to the engine and that due to roadway shocks. Measurement of headlight glare upon the roadway was made by obtaining continuous records of the illumination of the driver's eye from opposing cars or other equipment, the apparatus used including a photoelectric cell mounted inside the windshield in a direct line with the driver's eyes, an amplifier specially designed to cover the range of illumination and an oscillograph for obtaining a photographic record. Partial results of these tests are given. The general conclusions reached are set forth in six divisions, the last being that 0.07 ft-candle at 100 ft. is indicated as a criterion of glare. |
Practical Noise Treatment of Automobile Bodies | THE noise problem in the automobile body is complex and encompassing due to the fact that no single angle of attack is either complete or by itself sufficient to produce the desired results. Such results must be in the final analysis appreciable to the passenger's ear. For practical purposes and to meet the requirements of the industry, the problem has been divided into two parts: (a) To secure better results or greater improvements, for the same cost or less, by finding the best materials suitable in the general body-insulation practices of today. (b) To secure a complete and well-balanced job, involving a broader application of materials found to be most practical and economical, or to develop unusual products possessing unusual properties and larger capacities to function properly under given conditions. The instruments and very thorough method used are just means to an end, as in other fields of research or experimentations in which so many here have played a part. Or we may say that he who rides and hears, may also ride and see what he hears, and what we see can readily be recorded accurately. |
Design Criteria for Turbomachinery Periodic Structures to Improve Tolerance to Inflow Distortion and Resonant Oscillatory Flows | The purpose of this paper is to discuss typical problems caused by pressure waves of large amplitude propagating in a circumferential direction in turbomachinery. Opportunities for design control of cascade resonance as a means of protecting turbomachinery from these pressure waves are presented. Some of the critical areas are compressor rear frame diffuser and main combustor instability, afterburner screech, shock wave flutter instability of high-pressure ratio, variable-geometry jet nozzles, compressor stall, compressor stage 1 blade fatigue failures, and labyrinth air seal fatigue failures caused by flexural vibration of the thin walls. |
Booster Engines for Commercial Airliners | This paper discusses some of the fundamental advantages of using a special booster engine (s) for augmenting the takeoff thrust of commercial transports. The additional thrust provided by this principal offers increased route segment versatility by providing a wider range of tradeoffs in the takeoff distance, payload, range, safety, and noise level patterns for a particular aircraft. It further describes the flexibility in configurations that this principle provides the manufacturer for a given model. Also discussed in general terms is how the limited flight envelope and short operating time required for booster engines can be used to effectively reduce the engine's weight and volume. |
Ford ?쏶??Frame | Since statistics indicate that front impact is the major accident type, Ford has been studying energy-absorbing structures for some time. Early designs such as the ?쐀all and tube??and ?쐒ail splitter??were discarded in favor of the ?쏶??frame. Details of the design approach and testing are given in this paper. Design objectives were increased effective collapse distance, compatibility with production practices, and maintenance of satisfactory noise, vibration, and harshness levels. Safety objectives are improved passenger compartment integrity and reduction of seat belt loads. Barrier crash tests at 30 mph (equivalent to collision into standing vehicle at 50 mph) were used to evaluate the design of the ?쏶??frame. Results of testing indicate that occupant restraint with seat belts, combined with front end structural improvements, offer the most promise for injury reduction during service front impact accidents. |
747 ENGINE INSTALLATION FEATURES | New approaches to problems such as noise, temperature control of accessories and equipment in the nacelle, as well as improved safety features, are necessary in a modern high by-pass engine installation. The means of supporting the engine, cowling design, and maintainability features combine to improve the state of the art that a more economic airplane will result. |
Producing a Quiet and Comfortable Cab | Farm tractor cab design with respect to quiet comfort and convenience is discussed. The areas of visibility, accessibility, environmental control, and noise suppression are investigated. Various approaches to accomplish optimum conditions in these areas are analyzed, components are evaluated, and design recommendations are made. |
Methods and Problems in Noise Reduction on High Speed Diesel Engines | This paper describes a newly constructed research facility which was specifically designed for noise reduction work on internal combustion engines. Various approaches for reducing engine noise are discussed, and a method which permits locating individual sources of structure-borne sound is reviewed. A measuring system for airborne sound, radiated from the engine surfaces, is described. Some new findings and new problems encountered in noise reduction work are discussed. |
Crash Research for Vehicle Safety | The Impact Sled, a full-scale laboratory facility which simulates vehicle accidents, has been in use at the General Motors Proving Ground since late 1962. This paper describes the facility and supporting instrumentation, and reviews some of the many types of tests that were run in the first year of operation. These range from tests of complete vehicles loaded with passenger dummies to tests of single components such as seat belts, seat adjusters, door locks, and windshields. This new research tool, which produces results comparable to those of the classical barrier impact test, has proved to be a valuable and versatile addition to the automotive testing facilities at the Proving Ground. |
Aerodynamic Effects on Automotive Components | The range of automotive components that are affected by air flow around the car is surveyed, with examples of the application of aerodynamic knowledge to brake and engine cooling, wind noise, dirt accumulation, wiper lift, body ventilation, and air leakage. Air pressure distribution patterns over an automobile are shown along with air flow visualization techniques. |
Recent Developments in Penetration Resistance of Windshield Glass | A twofold improvement in penetration resistance of laminated safety glass for use in vehicle windshields has been achieved. A new test procedure has been established which will provide better correlation of test conditions to accident conditions than present tests do. Present windshield material and the new safety glazings are compared. |
Airport Compatibility with the SST - Problems of Ground Support Equipment | The compatibility of a supersonic transport with 15 international United States civil airports is examined in the principal areas of: terminals, passenger handling, and ground support equipment; runway length and pavement strength; and airport and community noise. Some new support equipment and facilities will be required although they are considered to be evolutionary in nature rather than requiring radical departures from current design. Runways and pavement strengths are generally acceptable as they exist today. Noise, both in the terminal areas and in the surrounding community, is expected to be equivalent to, or less than that of contemporary subsonic jet transport aircraft. |
Automobile Driver Eye Position | This paper reports results of a driver eye position survey made to provide the automobile industry with standardized data on driver eye location. Coordinate anthropometric measurements of eye position and top of head were recorded on film by a special photogrammetric technique. Data were smoothed into elliptical tangent cutoff percentile contours referenced to car body inch-lines and to points on the manikin. Results revealed a new shape to the driver?셲 eye position zone, compared to the area outlined in SAE J906, Glazing Manual. |
Efficiency in the Use of Shop Space | The growth rate of motor common carriers of general commodities has been greatest from 1950??960. Being a service business, the increased facilities required, primarily the freight terminals and garage buildings, necessarily lagged behind the business being handled. Many factors must be considered before construction is begun. Planning necessarily includes geographical location, adequacy to handle the vehicles that will be assigned for maintenance, design of the building, and the extremely difficult matter of cost. The author?셲 concept of the most efficient garage building is that it be rectangular in shape, have a flat roof, parallel service bays of a standard width with corresponding power-operated overhead doors, space heaters of the self-contained type mounted overhead, storage space located on second floors, and all stationary shop equipment mounted overhead or under the floor. Most important though is the efficient use of all floor space. |
An Approach to the Isolation and Control of Vibration in Light Business Aircraft | This paper presents an approach utilized by a light business aircraft manufacturer in resolving vibrational problems. The discussion relates the principle sources of vibration; objective briefly explores the consideration of priority in the operational range of the aircraft. The approach phases--preventive measures, theoretical application, and practical application--are illustrated through an actual vibration problem solution. It is concluded that this approach has proved satisfactory and that the importance of the practical aspect cannot be underestimated. |
An Automotive Living Room on wheels | The family car of a not-too-distant tomorrow will be ?쏿n automotive living room on wheels.??An air-conditioned vehicle equipped with television for back-seat riders, pull-out tables for games or dining, vanity-table and clothes-storage compartments, seats that convert into luxuriously upholstered davenports, or serve as sleeping couches when the car's recessed window blinds are pulled down. The power plant and driving line will be simplified to one of three procedures: a front engine front drive, a rear engine rear drive, or a turbine or fuel cell all-wheel drive. The entire design will be based on the largest possible ?쐋iving room??mounted between the most reasonable wheelbase and without noticeable overhang. |
A Shipbuilder's Views on River Towboat Vibration | This paper discusses causes, prevention, and possible corrective measures for river towboat vibration. Also discussed is the problem of resolving the amount of vibration acceptable to both owners and builders before corrective action is indicated in a specific vessel. The author suggests that sufficient research into towboat vibration be accomplished to establish some numerical parameters that can be used as standards of acceptance for vibration limits. |
Wind Noise - A Practical Approach | The principle cause of objectionable wind noise in the modern automobile is small air leaks in certain critical areas. The aerodynamic shape is insignificant in overall wind noise. The critical areas in order of importance are: 1. Vent window and door to ?쏛??post sealing from the roof rail to about a foot below the beltline. 2. ?쏞??post area at beltline. 3. Upper rear of front door area. 4. All other areas from roof rail to a foot below the beltline. Conclusions reached after extensive testing show that wind noise can be eliminated by good sealing about the doors and windows. |
Vehicle Vertical Vibration and Tire Performance | In the first part of this paper methods recently developed for the study of the oscillations of running vehicles are described as well as two types of analysis. Some information about the apparatus used for recording and analysis are given. In the second part the results of the analysis of the vertical vibration of a car fitted with three types of tires running on various types of road at various speeds are presented and discussed. Finally, in the third part, the possible influences of tires on the vertical vibration of the vehicle are surveyed. The viscoelastic deformations of the tires cause middle frequency oscillations which are transmitted from the tires to the unsprung masses and to the car body. |
THE POSTWAR CAR AND THE A-BLAST?쫁HAT ARE THE ODDS? | WHAT would happen if an atomic bomb were to explode at noon tomorrow without warning of any kind? Would the automobile turn out to be a death trap for many of us or would it offer as much protection as the ordinary building? Would there be any advantage in having the car turned away from the center of the blast or to having the windows rolled down? Would it be safer to crouch down on the floor of the car at the first sign of an atomic explosion? Would it be safe to enter our cars as soon as the first effects of the explosion have subsided? Would the cars run? It was to find the answers to some of these questions that a group was invited to observe an experiment at the Nevada Proving Ground of the Atomic Energy Commission. This group - which became the SAE-FCDA Advisory Committee - wrote the accompanying report, which tells about the experiment and some of the things that were learned. A. L. Haynes of Ford is chairman of the committee. Other members are: R. B. Alexander of Packard, William Christensen of Nash-Kelvinator, V. B. Corey of Willys, N. F. Hadley of Chrysler, E. J. Martin and M. V. Muzzy of GMC, W. W. Smith of Studebaker, A. D. Wagner of Hudson, and R. C. Sackett of SAE, secretary. |
A TECHNIQUE FOR DETERMINING THE OCTANE NUMBER REQUIREMENTS OF COMMERCIAL VEHICLES | Despite the size and importance of the fleet market, refiners have little information on the antiknock requirements of commercial vehicles. Considerable interest has been displayed in obtaining reliable data in this area. Some road survey data have been obtained in the past; however, truck engines are more prone to high-speed knock due to today?셲 more sensitive fuels and higher governed speeds. Knock under these conditions is more damaging and cannot be heard due to the masking effect of the high level of vehicle noise on the road. A chassis dynamometer technique has been developed to overcome this noise barrier and thereby provide realistic octane requirement data. Data obtained with this technique on commercial-type fuels were used to construct what is described as an ?쐎ctane requirement map?? This map extends the usefulness of the data and is a unique and effective means of expressing octane requirements, particularly how requirements are related to the sensitivity of the fuel. The map is also used to describe a new concept in determining relative engine severity. |
Automobile Side-Impact Collisions, Series II | Engineering methodology and research techniques, applied to 12 intersection-type automobile collision experiments, provided data on four speeds of impact and on three positions of impact. Anthropometric dummy motorists provide collision force and kinematic data for several conditions of restraint. Advanced photographic equipment identify new approaches to solution of the motorist collision injury problem. Specific data include tri-axial acceleration patterns for motorist head and chest and for car passenger compartment; identification of many factors associated with door latch failure and motorist ejection; demonstration of protection provided by the shoulder strap and lap belt combination; preliminary findings on tempered side window glass breakage and related head impact accelerations; collision dynamics and why modern car design has reduced probability for intersection collision roll-over; car collision deformation, skid patterns, and cost to repair damages are given for these controlled exposures. Successful programming of collision transducer patterns for data reduction by 7090 computer also is described. |
SST Operations and Maintenance Considerations | The SST pilot will have at his command more automatic equipment and better readout and displays to control noise level near the airport, to program the climb for minimum sonic boom, and to operate the airplane to lower weather minimums than on any previous transport. Yet, Boeing believes the typical senior airline captain will make the transition without any difficulty. The SST mechanic will have new and larger facilities, will handle bigger and heavier equipment, will learn to maintain airplanes still hot with residual heat, and will learn to maintain and repair that new metal titanium. Yet, the mechanic will find the SST maintenance and repair the best planned and organized of any airplane program to date. |
The Body Engineer's Role in Automotive Aerodynamics | Aerodynamic streamlining is assuming greater importance with our sustained driving speeds on new expressways. Benefits of streamlining include reduced wind noise, reduced lift and better stability, improved acceleration at passing speeds, higher cruising and top speeds, better fuel economy, and reduced initial costs. Basic principles of aerodynamics for automobiles are presented. Application of these principles are discussed and depicted for different types of automobiles and a tractor-trailer unit. Tables, formulas, and examples are included. Trends show aerodynamics as a factor of increasing importance for the automobile. It is suggested that a joint training program be initiated for body engineers and aerodynamicists with classroom studies based on detail design problems. |
A New Look at the Aircraft Noise Problem | This paper presents an analysis of the airport community noise problem, based on the assumptions that some significant adjustments will be made to reduce the impact of aircraft noise on the community, and that these adjustments can be made in an atmosphere of cooperation among engine and airplane manufacturers, airline and airport operators, and communities. Such cooperation can make available combined know-how to arrive at adjustments that will cause minimum loss to all interested parties. |
Control of Double Images in Automobile Glass | This paper first examines the optical principles involved in the formation of double images so that glass may be evaluated for this property in the design stage of automobile windshields. It then describes a new instrument, the local curvature and wedge meter, which has proved to be useful in determining the extent to which each of the three factors of curvature, inclination, and wedge has contributed to the presence of double images. |
Silent Mercury Rankine Cycle Power System | A silent mercury Rankine cycle power system is under development at TRW for U. S. Army Mobility Command's Engineer Research and Development Laboratories, Fort Belvoir, Va. The 3 kwe SCAP (Silent Compact Auxiliary Power) system is a power generator unit designed for various hydrocarbon fuels. The main advantages are portability and the inaudibility at 100 ft with a low ambient noise level. The system consists of a mercury boiler, a high-speed mercury driven turboalternator pump unit, an aircooled mercury condenser, and necessary system controls. Since this system converts heat through a closed loop mercury Rankine cycle engine into useful electrical power, the design is adaptable to burning indigenous fuels. A complete 3 kw useful electrical output system burning hydrocarbon fuels will weigh 125 lb and have a fuel consumption of 6.35 lb/hr. |