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During the past several years the problem of wake turbulence has received considerable attention. As a result of research programs sponsored by the Federal Government and private industry, the hazard of wake turbulence to light aircraft has been well documented. In this paper it is emphasized that relatively large aircraft can also be susceptible to vortices generated by large jet transports. This conclusion is based upon a review of accident records and the results from a computer simulation of the aircraft-vortex interaction. The computer simulation consists of the equations of motion with six degrees of freedom as well as control input by the pilot. Procedures are recommended for avoiding dangerous vortex encounters.

This paper explores some methods for circumventing the difficulties in interpretation of skid and traction tests caused by variations in speed, water depth, and road surface. Testing data are analyzed with a new approach using a graph of peak coefficient against slide coefficient. These analyses show that the tire and surface do not change greatly in basic frictional response as test speed changes. However, changes in coefficient do occur on most wet surfaces as the test speed is varied. Data indicate this to be the result of changes in the percentage of the tire penetrating the water film to reach the road surface. Data obtained under nearly identical conditions on different days vary. Least variation occurs in the low-speed peak coefficients, the slide coefficients, and the sum of these coefficients obtained either on dry surfaces or on surfaces wet with very thin water films.

The Experimental Safety Vehicle powertrain and fuel system developed by General Motors in compliance with Contract DOT-OS-00095 with the U.S. Department of Transportation include several special features: a low engine accessory package to meet the front visibility down angle of 8 degrees, engine and transmission mounting for retention at high decelerations, a light aluminum engine, an over-the-rear-axle fuel tank, and a unique evaporative emission fuel pipe routing. A comprehensive test program was planned and final testing to validate contract specifications was conducted.

Business aircraft-a nongeneric term to certification authorities-are being given increased attention by national and international bodies concerned with noise reduction. This paper reviews the efforts of these groups from a regulatory standpoint. The status of domestic requirements in the United States and abroad is presented. Technical procedures of promulgated and proposed standards are discussed. Business aircraft are separated into turbojet-powered and propeller-driven categories, and each is presented in terms of recent certification experience. The relationship between domestic certification programs and those of the International Civil Aviation Organization, and between domestic and foreign programs are presented. Finally, a brief look is taken into the future for the efficacy of business aircraft noise certification programs.

A program, under the sponsorship of the U.S. Air Force Aero Propulsion Laboratory, is now under way to provide the computational tools necessary to predict noise signatures for small turbopropulsion engines and to design attenuation equipment as required to meet specific low-noise goals. The 24 month program, scheduled for completion in August 1973, involves the analysis of turbine engine noise prediction and attenuation methods, as well as the experimental verification of these analyses with full-scale hardware. This paper reviews the methodology development phases and examines acoustical data from bare and attenuated engine tests.

The world's largest mining end dump truck, the Vcon 3006, utilizes several innovations to raise vehicle performance limitations significantly and to increase the productivity/operating cost. Its capability of hauling 250 tons on eight 36.00 X 51 tires with equal load distribution and reduced load variations at increased ton mph values is provided by a walking beam frame and four independently suspended oscillating bogeys on liquid spring suspension struts. Individually powered wheels with single tires provide exceptional traction and reduce tire scrubbing in turns to a minimum. The improvement of tire life that this vehicle concept demonstrates is of major importance to the utilization of large trucks. Its 3000 hp diesel locomotive engine provides a low fuel consumption, high performance, and reliability unmatched for a vehicle in this class.

Some of the characteristics of traffic accidents involving small cars in Europe are reviewed. A classification procedure is suggested whereby crashes may be categorized by their equivalent test in the laboratory. A sample of accidents is used to illustrate this procedure and the collision characteristics. The limited relevance of the distributed frontal barrier test to real world accidents is shown. Examples of particular features which produce injury are illustrated by cases. Three-point belts are discussed, and some injuries associated with poor positioning are illustrated. Small car steering assembly design is mentioned because field experience suggests that actual function of the steering assemblies in crashes is still not optimal. Problems of seat deformation and mounting failures in relation to injury patterns are discussed briefly, and the crash performance of glass reinforced plastics is mentioned.

The Pneumatic Spring Subcommittee of the SAE Spring Committee recently updated the information report J511a relating to Pneumatic Spring Terminology for the SAE Handbook. It is also in the final stages of writing a Manual on the Principles and Application of Pneumatic Springs (HS J42). This paper is a review of that manual. It outlines basic principles, types, applications, special cases, and associated equipment. It will also apprise suspension engineers of the general capabilities and limitations of pneumatic springs. The production of these springs is also covered.

Temperature requirements of 1800-2000 F impose a near-ceramic approach to the application catalysts for auto emission control, and the unit structure or monolith substrate is discussed in terms of its specific requirements. Surface modification to include high-surface-area coatings for optimum dispersion of active components is of primary consideration. In addition, progress is reported on some of the approaches to the problem of blending normal catalyst properties for low-temperature activity with the ceramic requirements and high-temperature exposure. Performance data from laboratory experiments and FTP-CVS evaluation tests are discussed in relation to contact time, material transport, geometric configuration, and aging. Physical durability, which is influenced by inherent structural properties of the monolith, must be capable of coping with extreme demands created by the continuously changing conditions within the catalytic unit.

The design analysis for a variable rate spring has been simplified by using an example which is symmetrical. In order for the variable rate spring to produce the desired ride qualities, specifications must establish rate curves-load and load height for the first, and also for the second, stages. Variable rate springs have the potential of improved ride quality over a wide load range, provided an adequate total deflection can be accommodated on the vehicle and the springs are designed correctly, with specifications which include control for manufacturing to obtain desired spring rates.

In the faceted reflector design for automotive lamps, the reflector is divided into easy-to-fabricate, circular cylindrical segments (facets) in a manner such that the reflector alone produces the beam pattern. The prescription for the facets is developed with the aid of computer programs which simulate the images from each facet and “build up” the desired light pattern mathematically, thus eliminating the normal “cut-and-try” experimental buildup. The design procedure was applied to a fog lamp with a 55 W quartz-halogen bulb and several prototypes have been constructed. The broad beam pattern from these lamps is most suitable for driving in a fog and the lamp with a clear lens offers styling flexibility. The faceted reflector concept can also be applied to headlamps, driving lamps, and signal lamps.

This paper serves as an introduction to the technology of alumina catalyst supports and relates physical and chemical properties of aluminas to the critical properties of finished catalysts. Although the emphasis here is upon the design of particulate catalyst supports, the treatment is sufficiently broad to be applicable in part to the use of aluminas in other ways, such as for coatings on other substrates. The information presented will be of greatest interest to those directly involved in catalyst development and manufacture, representing the viewpoint of a supplier of raw materials and formed alumina substrates to the catalyst industry. However, it may also appeal to those wishing to develop a further background on catalyst properties and gain some understanding of the limitations of feasible design of catalysts, which, in turn, often depends upon the flexibility and limitations of the catalyst support employed.

Particulate catalysts, consisting of porous solid particles, have been under intensive development for the control of automotive emissions. Such catalysts contain base metal and/or noble metal active components dispersed on high surface area alumina supports. Consideration is given to the physical and chemical properties of both supports and catalysts, and to the relationship between some of these properties and catalytic performance. It has been found that low bulk density and the presence of macroporosity improve conversion efficiency. At high temperatures, transformation of the support from a high surface area alumina to crystalline alpha alumina causes shrinkage, a deterioration of mechanical properties, and catalyst deactivation. Support interactions with certain activity promoters accelerate this adverse transformation. Stabilizers have been found that repress the alpha alumina transformation. Base metal catalysts are extremely sensitive to sulfur poisoning.

Dynamic analysis of the resonant beam machine is presented. Equations typically used to determine the dynamic properties of a rubber product are derived from a simplified model. A complex mathematical model representing a more realistic parametric system identification is formulated. Using the complex model as standard, the errors in the results from the simplified model are identified quantitatively, and it is shown they can be considerable. The sensitivity of the errors to the system parameter variations is also shown. These machine errors may be virtually eliminated by measuring the transmitted force and displacement across the sample.

This paper describes a method for determining the dynamic properties of rubber compounds through the use of a dedicated mini-computer. Topics under discussion include the application of the Fast Fourier transform and its inverse as a rapid method of determining an array of nonlinear coefficients that describe the component force vectors. A discussion of the controlling algorithms in the determination of the dynamic spring rate, nonlinear damping coefficients, and hysteretic energy absorption through the implementation of the Fast Fourier transform is presented. The advantages of this method include relatively low cost, fast results, and simplicity of operation. The implementation of the mini-computer toward this application opens a new field for developing compounds with low damping coefficients where present methods of measurement may not yield consistent results. Test efficiency, repeatability, and reduction of development costs are the principal advantages.

With the increasing emphasis on the dynamic performance of elastomer mounts, the rubber manufacturer has been required to develop, produce, and control elastomer mounts with more versatility and precision than ever before. To accomplish this, the rubber manufacturer has become more involved with dynamic testing and dynamic performance while working closer with the automotive industry on cooperative engineering programs and correlation testing. This paper will discuss the manufacturer's role in preproduction engineering programs and requirements, production control of mounts, and control related correlation.

The search for greater accuracy and precision in the measurement of dynamic properties of elastomeric components used in the automotive industry is a never-ending endeavor. This paper considers the statistical approach to designed experiments for evaluation of individual test machine repeatability and test machine differences. The approach is a discussion of the “Analysis of Variance” (ANOVA) technique and the mechanics of solution. The accuracy and precision variables are then applied to the technique for analysis. Included are the results of a precision error experiment conducted at General Tire and a round-robin test program, which was conducted through the joint ASTM-SAE Technical Committees on Automotive Rubber (TCAR Section 11.65B), both using the ANOVA statistical approach. The MTS 830 employing the transmitted force test method was used in the round-robin.

An instrumentation system is described which provides on-line computation and direct readout of C and K. The system relies on the measurement of force and displacement or velocity across the sample and is independent of the type of test machine. Errors introduced by unwanted phase shift in any instrumentation system are discussed. This is overcome in this measurement system by phase compensation. Calibration of the system is described in which an overall system accuracy can be determined independent of test machine or rubber sample. This system has been specifically designed for measurement of dynamic properties of rubber and provides the operator with direct readout of C and K scaled to engineering units, thereby reducing potential operator error.

The purpose of this paper is to show the development of the Dynamic Rubber Test Machine as an engineering and production (quality control) tool from the standpoint of a machine supplier. Problems encountered in the design, fabrication, preshipment checkout, and installation of equipment into customer's facilities are discussed. Correlation of equipment is explored as it relates to the dynamic spring rate and the damping constant of elastomer products. Certain techniques and hardware adaptations have aided in improving the repeatability of tests of the resonant beam system. The information given is not intended to be all inclusive, but as a report of the work in this field to date.

With the goal of reducing the high current peaks which occur in lead-acid batteries used for electric vehicles, a new power train incorporating an inertial storage device coupled to a continuously running electric motor has been designed. The power train consists in part of an electric motor designed for efficient operation over a narrow speed range. Once activated, the motor runs continuously even though the automobile is stopped; during the rest periods the motor stores energy in a kinetic device which acts as an energy load leveler. Such an electric motor-inertia hybrid power train has several advantages: high-power output capability, all mechanical regenerative braking, extended battery life, increased electric motor efficiency, and elimination of expensive solid-state motor controllers.