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This paper presents the results of two static tests of structures in use on certificated aircraft and a description of finite element models of these structures. Comparisons of the results of the static tests and the predictions of the finite element analyses are given. Problems encountered in the development of the finite element models are presented, and solutions to these problems are discussed. Implementation, applications, and functional aspects of finite element analysis are also discussed. This paper does not cover the basic mathematical development of finite analysis, nor dynamic analysis applications.

This paper describes a rational basis for making tradeoff decisions on cost and weight for structures made of various materials. Unit cost and empty weight data have been gathered for a variety of consumer products and of aircraft. As examples illustrating potential applications of filamentary composites, the cost/weight tradeoff ratios were calculated for three typical aircraft structural components: a landing-gear cantilever-spring strut, an I-beam, and a shear panel. In addition, weight analyses of fuselage structures were made for designs using a variety of materials and these structural concepts: monocoque, sandwich, and ring-and-stringer-stiffened cylinders. With the cost reductions anticipated in the next three or four years for graphite and boron filamentary composites, fiber composites hold considerable promise for general-aviation aircraft.

This paper presents a brief review of some of the contributing factors in design for fatigue and fracture of advanced composite materials. Consideration is given to the roles which the fiber and matrix have in the static, fatigue, and fracture response of laminated composites. The statistical aspects of failure are also discussed.

A successful short-haul transport must satisfy customer and marketplace requirements and be attractive economically. This paper examines the marketplace in the late 1970 time period to determine the payload-range and other performance requirements for a wide-bodied twin-jet transport. Environmental and operating cost targets are established, and the size of the market is estimated. An “optimal” design is then described which essentially represents the best possible airplane using the technology available in the time period best suited to the customer and marketplace requirements. Design data are presented that show the sensitivities of the design to some of the primary configuration variables. Certain design compromises are considered that have to do with airframe commonality with the manufacturer's other transports.

Since the advent of jet freighter aircraft in the 1960s, a great deal of attention has been placed on the future of air freight and particularly on the aircraft that will carry it. Studies for the “ultimate” optimized air freighter have been many and varied. Concepts have generally been market oriented, aircraft oriented, or ground systems oriented. The base for these studies has been so broad that a set of requirements for a new generation of freighter aircraft and supporting ground systems has not been finalized, and the development funds therefore have not been allocated. This paper discusses some of the possible aircraft and ground systems concepts that might satisfy the future market, the parametric and specific studies that led to these concepts, and the economic constraints that will have to be overcome if the true market potential of air freight is ever to be realized.

The A300B is a wide-body, twin-engined aircraft developed jointly by leading aviation companies throughout Europe and the United States. It has been built for the major intra-European route structures and the short-haul route networks of North America. Engineering of the aircraft maximizes reliability and economy on the exacting short-range operations. The first A300B off the line flew on Oct. 28, 1972, just 3-1/2 years after go-ahead, and by the end of 1972 had flown 98 h. During 1973, that first airplane will be joined in flight testing by three others, in a program leading to certification by the end of 1973. Initial deliveries to airlines will be made early in 1974.

This account of the development of the Concorde and its eventual manufacture is highlighted by the cooperative efforts of two dissimilar countries, brought together by a singular vision and united by a determination to create a practicable design of a mass-transport aircraft. The innumerable problems encountered cannot be completely covered in this capsule history, but the overall review given here presents a new approach toward solving the economic troubles of the air transportation industry, which may possibly be affected by impractical competitive practices.

This paper discusses the design objectives of and a development cycle for a second-generation supersonic transport (SST). The environmental impact of technological advancement and the rapidly changing economic market produce a wide divergence of possible programs for the 1985 time period. Areas of technological advancement that can move in the direction of the second-generation design objectives will be included. Some of these advances require development of a methodology to be able to reduce the technical risk of application to a commercial SST and some require exploratory development.

This paper assesses the impact of meeting the environmental requirements for reduced noise and air pollution on the cost and technical design considerations for engines to power the next generation of commercial transport aircraft. Engine candidates studied are in the advanced (new) design class as well as derivatives of existing high-bypass turbofan engines which offer attractive total cost of ownership features. The elements of operating cost are analyzed for the effect of the engine on aircraft economics, with special attention being given to operating cost differences between new engines and those derived from current in-service high-bypass engines.

The use of wax-crystal modifiers for improving low-temperature operability of diesel fuel has not been possible in the United States because the large crystals could not penetrate the very fine porosity of fuel filters. The development of new, extremely potent additive packages has solved this problem by reducing the size of the crystals precipitated in the diesel fuel. The smaller size allows them to pass through the fine filters of auto-diesel equipment at temperatures well below the cloud point, even under extreme field conditions. On the basis of successful testing of additive-treated diesel fuel, cloud point can no longer be considered as an indication of operability limit in auto-diesel equipment. It is desirable, therefore, to develop a laboratory flow test that predicts the field performance of diesel fuels-flow improved or not-and accept it as the basis for a new operability guideline for diesel fuel equipment.

The emission index (grams of species per kilogram of fuel) field within a regenerative turbine combustor has been mapped using a water-cooled sampling probe. The probe employed a choked orifice to simultaneously determine the local temperature. Derived from measurements are: air-fuel ratio, combustion efficiency, average fuel velocity and fuel distribution factor. Methods of averaging the discrete data are developed. A comparison of the data obtained when the combustor was operated on each of two fuels revealed that the use of methanol leads to lower nitric oxide but higher carbon monoxide emission than does the use of diesel fuel.

This paper presents the results of a parameter variation study conducted on typical single- and double-articulated vehicles using the AVDS II computer simulation model. The vehicle dynamic responses and driver steering and braking response demands during 12 ft wide lane-change maneuvers are determined for varying discrete values of maneuver length vehicle velocity, road-tire friction coefficient, fifth-wheel damping, vehicle geometry (fifth-wheel location), and vehicle loading. Effects of brake unbalance and aerodynamic loads on vehicle responses are also evaluated.

Analytical-experimental studies were conducted on a tractor-semitrailer vehicle performing prescribed lane-change maneuvers. This paper shows the validation of the Articulated Vehicle Dynamics Simulation model (AVDS II) with full-scale tractor-semitrailer field tests. Experimental data on the tractor trajectory and braking were used as computer input, and the simulation model response results were compared with the vehicle responses from the experimental tests on a time-transient basis. Analytical-experimental validation is shown for varied vehicle speeds and braking during maneuvers.

The advent of turbine power for commercial vehicles raises the question of how best to convert the promised weight saving into an equivalent increase in payload. The practical importance of the method adopted to maintain maximum axle load limits, in the case of truck tractors, lies in the profound effects on ride of the wide changes possible in the dynamic index. This paper reviews the basic principles of weight distribution effects on vehicle ride to bring out the quantitative significance of the dynamic index. This criterion is then applied to the prediction of the consequences to riding quality of any combination of fifth-wheel offset and wheelbase, at constant axle loads. General equations are derived and their use is illustrated for the case of a typical tractor, with assumed powerplant weight reductions up to 2000 lb. The principal conclusions are: 1. Axle loads should be maintained by using the shortest possible wheelbase combined with slight increases in fifth-wheel offset. 2.

After-injection is the introduction of additional fuel to the combustion chamber after the end of the main injection. It is a persistent diesel fuel injection problem which usually results in reduced engine power and economy and increased emissions. After-injection is caused by uncontrolled pressure transients at the injector after the opening of the pump spill port. These pressure transients are related to the wave propagation phenomena in the high-pressure pipeline connecting the pump and injector. Use of experimental trial-and-error methods in attempts to control this phenomenon has met with limited success. The analytical control method described in another paper is used to determine design means by which after-injection may be controlled. Further investigation and evaluation of two design changes which release the injection system excess elastic energy in a controlled manner are considered herein. One design change is the addition of a control valve in the pump delivery chamber.

The increasing requirements imposed on diesel engine manufacturers have required the study of fuel injection system faults and the development of means to eliminate them. Until now, improved injection system characteristics have been obtained by experimental trial-and-error procedures. These procedures, however, have proved to be inconvenient, tedious, and have had limited success in eliminating system faults such as after-injection. This is mainly because the transient nature of the injection process requires a more thorough study of the system time-varying parameters. In this paper the residual transients which cause after-injection are analytically investigated. The control of these transients required specification of some system parameter. The rapidly varying nature of the system pressures and flows prevented the use of these variables as control parameters.

The simulated calculation of a fuel injection system is now possible by the use of a computer. However, this calculation does not seem completely satisfactory. In the conventional methods of calculation, separate calculation equations must be used when a void (the absence of oil) occurs in the injection system. Furthermore, the boundary condition equations applied at both ends of a high-pressure pipe were believed to be inadequate. In this paper, several improvements are attempted. A quantity that varies from positive to negative value is used as the fundamental variable in the calculations. Also, experiments were made using a test apparatus with a transparent boundary part for both observation and measurement. Moreover, incorporating the fundamental variable, the boundary condition equations were made applicable both to the state of compression and a void condition.

Comparison is made between the transient response of a medium-speed, turbocharged diesel engine subjected to sudden load changes on a test bed and the response of a computer simulation model of the engine. Brief details are given of the simulation techniques involved and the data required to set up the model. Despite close agreement of model and engine steady-state results over the whole normal operating range, the transient responses of the model were initially found to be much faster than the test-bed responses. It is shown that the most important factor causing this difference is the lack of knowledge of the combustion at low air-fuel ratios and hence prediction of engine exhaust temperature during transient operation. Good agreement was obtained when this was modified.

One of the methods for improving the transient response of a turbocharged diesel engine is to accelerate the turbocharger by injecting air onto the impeller of the compressor. This paper describes experiments carried out on a turbocharger test rig in which air was injected through nozzles at the rotor tip of the centrifugal compressor; performance characteristics are presented. Results from these tests were then used to modify a digital simulation model of a medium-speed turbocharged diesel engine so that air injection could be applied at the onset of a load. Calculations show the predicted improvement in response of the system to step-load changes.

Although the flow through the poppet valves of the four-stroke cycle engine and piston valves and rotary valves of the two-stroke cycle engine is unsteady, because of the periodic area change of the flow passage of the valves, the flow characteristics of these valves is usually evaluated by steady-flow conditions. The author experimented with flow characteristics under steady and unsteady conditions by using a rotary valve, in order to specify the difference between them and to identify the factors that effect this difference. According to the results obtained, inertia of the mass of the fluid in the flow passage of the valve is the most important factor in creating this difference of flow between them. A theoretical analysis of this inertia was found useful in predicting the effect of various parameters on flow through the passage of the valve under an unsteady condition.