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This paper discusses the possible impact of the FM tape recorder and servo-hydraulic actuators on the testing of automotive structures. The use of tape recorders and automatic data reduction systems will permit more accurate definition of service conditions and properly “set-the-stage” for laboratory testing. Servo-hydraulic strokers should encourage better laboratory simulation because of their great flexibility. Test set-up time is reduced, fixtures can be simplified and load control is more precise. Simultaneous multiple inputs can be controlled as to amplitude and phase relationships.

The Douglas Aircraft Co. has been involved in testing the Saturn S-IV stage at the Sacramento Test Center for the past two years. The propulsion system for the S-IV stage consists of six Pratt & Whitney Aircraft Co. rocket engines specifically designed for high-altitude start and operation. During static firing tests of this engine at sea level, a steam jet ejector in combination with a diffuser is used to simulate altitude conditions. The intent of this paper is to examine the performance of this altitude simulation system, and to discuss the problems encountered in making it operational.

The FASTI system (Fast Access to Systems Technical Information) is a computer oriented methodology of pinpointing system malfunctions. This technique is based on integrated system simulation and analysis, documentation of generated malfunction isolation data, rapid retrieval of these data for a specific problem, and solution at the point of use. The simulation technique also develops many types of data applicable to various engineering diciplines and critical technical management areas. Although the peripheral benefits are significant, most important is that malfunction isolation data are rapidly available when needed to avoid catastrophic consequences and keep recovery time to a minimum.

This paper describes theoretical analyses performed on cylindrical and spherical propellant tanks to establish the basis for selection of the proper mode (electric and magnetic field configurations) of operation of the cavity. Extensive experimental investigations were then conducted. Scale models were constructed and loaded under conditions simulating zero gravity and applied accelerations with typical fuels such as hydrazine and unsymmetrical dimethyl hydrazine. The results of these measurements have verified the theoretical predications and have established the basic feasibility of this radio frequency technique.

New concepts for submarine propulsion plants are continuously being presented to the Navy for review and possible application. An analytical method is now being used to determine the effect of powerplant weight and thermal efficiency on the cruising radius, speed, and vessel displacement. A mathematical model representing the propulsion plant and vessel hull was prepared and, by means of a digital computer, the effects of varying several design parameters were studied. By comparing the predicted performance of several types of powerplants with the results of the computer study, it is possible to select those which justify further development for Navy use.

The Dynamic Simulator facility provides operational simulation of the complete navigation subsystem for the present Polaris class submarines as well as major portions of subsequent classes. The simulation utilizes general purpose analog computer equipment in conjunction with realistic and operative displays and controls to represent the overall operational conditions of the subsystem. This facility is used to analyze interactions, transients, and steady-state performance levels which otherwise could not be readily studied, and to train navigation personnel by presenting realistic displays of system performance.

The terms “reliability” and “reliability design” have emerged as popular words to describe a discipline for minimizing failures or operating difficulties in complex mechanisms or systems. Little recognition has been given to past or traditional engineering practices which have been evolved to achieve this objective along with the primary one of fulfilling a specific operational need. The purpose of the following discussion is to describe in non-academic terms how a rather high degree of reliability has been achieved in developing military airframe structures, the difficulties and inaccuracies associated therewith, and some aspirations for the future. It is not intended for structural designers and fatigue specialists who should be better informed on the technical procedures involved than the writer.

The use of plastic scale models to determine metal stress in automotive equipment is an increasingly important consideration from the standpoint of saved time and reduced costs and space requirements. The Chrysler Corp. has developed a plastic model technique that provedes good correlation with full scale results. Its development and application are described.

Design features of the XV-5A lift fan V/STOL airplane combine uniquely to give it the speed performance of a jet in conventional flight and the take-off and landing capability of a helicopter. The simulation program represents three main functions in the aircraft development cycle: mathematical models optimize the flight control system design; an actual control system replaces its mathematical counterpart; simulation enables the test pilot to become completely familiar with cockpit controls and handling. Flight simulation faithfully represents aircraft dynamics and presents a realistic visual display of position and motion of the aircraft with respect to the earth.

The design, construction, and typical application of a portable, passive element network analyzer is described. This device was designed for use in the simulation, analysis and design of complex aerospace systems. When programmed, this analyzer becomes an electrical model of a physical system rather than a computer for the solution of mathematical models which represent a physical system. The advantages of this design are its small size, economy, and availability of all programming elements on a single compact unit. An example problem is also described to illustrate the typical application of the network analyzer in the solution of engineering problems.

Introduction of the exhaust heat exchanger and variable geometry turbine add to the complexity of the gas turbine control problem, necessitating the use of analog simulation methods for control analysis. Simulation from basic thermodynamic equations results in excessive analog equipment requirements and loss of accuracy because of the large number of algebraic operations. This paper describes a simplified method that makes maximum use of steady-state data obtainable from a digital computer program. Comparison of equipment requirements and cost of conducting a typical study by two methods of simulation are presented.

The use of computer-based mathematical models to simulate space logistics operations provides the program planner and systems engineer with information needed in selecting the flight transportation system, the mission profile, the scope of the space activities supported, funding requirements, and schedules. Monte Carlo techniques are used in implementing the simulation model. An example involving the furnishing of logistics to an extraterrestrial base is introduced. The inputs to the model are discussed, and typical results are shown.

The study of an acceleration sensing fuel control system for gas turbine engines using a small analog computer is presented. The transfer function technique is utilized in simulating the system which permitted a study of the system performance using a minimum of computer components. An actual engine was run using an electrical analog of the control developed on the computer. A system stability map (plot of maximum stable proportional gain versus maximum stable integral gain) is presented comparing calculated, computer, and actual engine results. The advantages of using the analog computer for control system analysis are illustrated.

This paper is concerned with an adjustable scale model capable of tracing maneuverability patterns of trailer trains. The transient kinematic paths of a multiple unit carrier of train configuration consisting of ten cargo units provided with conventional two wheel steering, conventional four wheel steering, and modified four wheel steering with a steering ratio and delayed steering action are investigated and discussed.

A comprehensive cycle analysis has been developed for four-stroke spark-ignited engines from which the indicated performance of a single cylinder engine was computed with a reasonable degree of accuracy. The step-wise cycle calculations were made using a digital computer. This analysis took into account mixture composition, dissociation, combustion chamber shape (including spark plug location), flame propagation, heat transfer, piston motion, engine speed, spark advance, manifold pressure and temperature, and exhaust pressure. A correlation between the calculated and experimental performance is reported for one engine at a particular operating point. The calculated pressure-time diagram was in good agreement with the experimental one in many respects. The calculated peak pressure was 10 per cent lower and the thermal efficiency 0.8 per cent higher than the measured values. Thus this calculational procedure represents a significant improvement over constant volume cycle approximations.

This paper presents an approach to the design optimization of a conventional landing gear system for a supersonic transport, from a structural loads standpoint. Frequency analysis considerations are related to the computer simulated response of the nonlinear gear-airframe interacting system. Variations of gear stroke are made to examine the coupling between the gear and the airplane structural response. Results of the method are shown and implications for fatigue and service life predictions are illustrated by example.

This detailed analysis of the Otto cycle considers the effects of dissociation, finite reaction kinetics, and irreversibilities such as heat transfer and mechanical friction on cycle performance and efficiency, and provides a highly flexible tool for investigating the complex relationships among engine variables. This mathematical model and the accompanying computer program offer a substantial computational advantage over the previous methods that employ charts and graphs and require a large amount of manual calculations. Also, the ability of this scheme to consider the effects of heat transfer and other irreversibilities considerably increases the value of the results.

Recent attention has been given to the use of computers for analyzing the Otto engine cycle. This paper describes the application of the IBM 7090 computer to the ideal Otto cycle, discussing (1) the general problem and overall approach taken, (2) required expressions to describe the processes taking place so that the properties of the material at each state can be determined, and (3) the actual method of computation employed.

Many systems that can be simulated on an analog computer can best be analyzed with the aid of statistical processes. This paper is concerned with: 1. Reasons for the statistical approach. 2. Various types of statistically defined inputs, including “white noise.” 3. Statistical analysis of the outputs, using analog computer techniques. The analysis of automotive suspension systems using stochastic processes is discussed as an example of this type of approach.

A method of developing a mathematical model of power-plants to simulate engine-governor, or servo systems on a d-c analog or digital differential analyzer is presented. Based on experimental data, the steady-state output of a powerplant is defined as a function of two variables. The dynamics is defined, and the steady-state performance is corrected for response and inertia effects. The resulting mathematical model is discussed with respect to computer applications, instrumentation, and techniques for compiling empirical data needed. Another application is monitoring performance of farm tractors, industrial equipment, and/or automotive systems under field operating conditions. The mathematical model is simulated by an analogous circuit of components that may be inconspicuously mounted on the powerplant in question.