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The method is presented which enables a prediction of vehicular performance relative to a specified physical environment. The discussion centers around the parameters which are required to specify the vehicle, the driver, and the environment together with the computational procedure used to estimate vehicular mobility in terms of these parameters. Analog and digital simulation results are presented for wheeled and tracked vehicles respectively.

A very large increase in the ratio of digital computer capabilities (memory capacity and operating speed) to computer cost is forecast in the next decade. This paper considers a number of aspects of the design, construction and use of modern digital flight and space trainers with the thought of exploitation of presently unobtainable computer capacity to maximize simulator usefulness and to minimize total simulator costs. New methods of visual and radar simulation made feasible only through the use of super computers are discussed.

This paper describes a device for the control of critical speeds consisting basically of a squeeze film oil damper between two non-rotating parts in parallel with a flexible bearing support. A mathematical model of the vibratory system is developed showing the existence of two different critical speeds as a function of damping. From the model, response of the system is predicted. A critical speed test rig was designed and fabricated and a test program was conducted. Results of the experimental investigation confirm the applicability of the model and the use of the device as a critical speed control. Further testing is reported on the effect of various design parameters on damping, and a simple method of varying the damping on the test stand during engine operation is shown. The results of the investigation were applied to the design of a similar device for a multistage compressor which was successfully operated with low amplitude throughout the speed range.

A new EVA/IVA simulation technique in which a servo-driven/computer-controlled simulator provides motion to the astronaut equivalent to that experienced in a zerog environment is described. The instrumentation systems required to generate the necessary input data to the analog computer, programed with the EVA/IVA dynamic equations, are discussed. The instrumentation consists of a load cell array to sense the forces and moments applied to the spacecraft by the astronaut during orbital activity and a unique limb motion sensor that continuously measures the astronaut's limb positions. The design considerations for the simulator are presented, and various space missions conducted on the simulator, with primary emphasis on EVA, are discussed.

Advanced space vehicle planning is analyzed from the economic approach to decision making. Optimum cost of program is found to drop with time despite rising launch traffic. Mathematical models are constructed with parameters based on earlier launch vehicle data. Effects of discounting on optimum investment are presented.

A physical model capable of credible simulation of human trauma is badly needed in automobile safety research. Development of such a model has been limited, not only by lack of biological and engineering data, but by lack of a coherent, sequential plan of attack on the problem. Such a plan, based upon the systems approach, is offered. The plan has two major phases. The first phase includes qualitative analysis, hypothetic modelling, and program planning; the second provides for emperic research, system modlling, and design, fabrication, and test of a physical model.

AN ELEVEN-DEGREE-of-freedom nonlinear mathematical model of an automobile traversing a variety of irregular terrain features and encountering a variety of roadside obstacles has been formulated and programmed for a digital computer. The primary objective of the described research has been to develop analytical means of evaluating existing and proposed roadside energy conversion systems. However, the developed computer simulation also has potential applications in the reconstruction of single vehicle accidents and in studies of the driving task at the upper limits of vehicle control. A unique feature is the simulation of combined cornering and ride motions. In its present form, the computer program includes open-loop evasive maneuvers. The results of a review of single vehicle accident statistics and measurements of structural load-deformation properties of automobiles, performed within this research program, are both presented.

This paper discusses reliability prediction, modeling and analysis activities which are taking place in the Apollo program, after first giving a brief summary of the program itself. Reliability modeling and analysis of a typical manned Apollo mission are discussed through an example, the switch selector in the S-IVB stage of the Saturn V launch vehicle. Benefits and limitations of the analytical approach are given. It is concluded that prediction activities have benefited the Apollo program, and they have been most useful as consistent tools for designers where complete communication is maintained between engineers performing the analyses and those engaged in designing and testing the hardware.

This paper describes a new mathematical model developed to account for nonlinearities between vehicles and tires. Lateral and vertical stiffnesses of tires are investigated because they have basic influences on the behavior of the car in sudden and severe maneuvers. The new procedure allows operational simulation and simplifies analyses of cars with different types of tires and suspensions. This is demonstrated by comparing vehicles fitted with a basic tire, a tire with larger lateral stiffness, and a tire with larger cornering stiffness. Calculations show the damping effect of lateral stiffness and the need for increasing both cornering and lateral stiffnesses.

The handling behavior of an automobile towing a full-size travel trailer at high speed is studied analytically. A computer simulation of the system indicates the proper range of design and load parameters for best handling quality and illustrates the effect of some hitch design parameters. Associated analysis provides supplementary insight into the factors affecting stability of automobile-trailer combinations.

The kinematics of rear-end collisions based on published acceleration pulses of actual car-to-car collisions (10 and 23 mph) were reproduced on a crash simulator using anthropomorphic dummies, human cadavers, and a volunteer. Comparison of the responses of subjects without head support were based on the reactions developed at the base of the skull (occipital condyles). The cadavers gave responses which were representative of persons unaware of an impending collision. The responses of both dummies used were not comparable with those of the cadavers or volunteer, or to each other. An index based on voluntary human tolerance limits to statically applied head loads was developed and used to determine the severity of the simulations for the unsupported head cases. Results indicated that head torque rather than neck shear or axial forces is the major factor in producing neck injury.

Studies were performed to determine which environments are germane to simulation during structural verification tests on future aerospace vehicles. Missions of proposed orbital and space vehicles and associated environmental conditions are defined. Effects of both natural and induced environments on structures are discussed and those necessary for simulation are presented. Results conclude that critical environmental conditions are experienced during exit from and entry into the earth's atmosphere. For the most part, the effects of the space environment are relatively insignificant on vehicular structures. Present environmental structural testing capabilities for orbital and space vehicles are presented and future development needs predicted.

Problems in environmental testing of orbiting and space vehicle structures are primarily caused by the limitations of the ground test facilities in providing adequate simulation of the operational environment. This paper will give an account of the specialized environmental simulation techniques developed and the analysis methods used to supplement the facility capabilities for the environmental test program of the Lunar Excursion Module (LEM).

New powerplants must be evaluated on the ability of the engine to provide increased customer profits. Mathematical simulation is an effective method of speeding this evaluation process. Results show the design requirements for a competitive turbine engine. Tradeoffs are shown between the high cost, sophisticated turbine engines with high thermal efficiencies and lower cost turbines with low efficiencies.

The evaluation of commercial vehicle brake system balance is a complex analytical task. Tractor-trailer combinations frequently include different brake designs on different axles, which have widely varying characteristics. In addition, variations in brake parameters such as pressure, response times, linings, and heat transfer under various operating conditions add to the complexity of analyzing the brake system. This paper describes a mathematical model of the vehicle brake system and a program for a digital computer to solve the mathematical expressions. Using the computer to simulate dynamic brake system operation, current designs can be evaluated rapidly for effectiveness and possible improvement, and future designs can be analyzed prior to expensive prototype fabrication.

A program of research was conducted to examine the validity of a digital computer simulation of an automobile occupant during a frontal, head-on collision. The simulation is designed to permit a detailed study of the effects of several types of restraint systems on occupant responses in a confined compartment, where injury-producing contact forces occur. The effects on occupant responses produced by the positions, orientations, and load-deflection properties of contacted interior surfaces are also simulated. This progress report covers one phase of a CAL long-range program of development of simulation techniques for study of occupant/vehicle and vehicle/obstacle collision responses. Detailed comparisons are presented of responses from instrumented sled tests and corresponding computed responses from the simulation. The comparisons include forces in restraint belts and on contacted surfaces, accelerations of the dummy, and the detailed kinematics of the dummy itself.

Three different methods of testing mobility systems of lunar surface vehicles (LSV’s) under simulated lunar gravity conditions and the types of mobility test articles (MTA’s) required for such tests are discussed. A proposed outline for an LSV mobility test program is given which is based on three types of MTA’s. These MTA’s are: a Block I, with a linear scale of 1:1 and a mass scale of 1:6; a Block II, which is essentially the MTA Block I ballasted to its full mass; and a Block III, which has a small linear scale and a mass scale corresponding to the applicable model scaling laws. The MTA Block II requires the use of a lunar gravity simulator; several types of such a simulator are being discussed.

The exact model rules for lunar vehicles whose performance on the moon has to be tested on earth are derived. A true picture of lunar performance can be obtained by taking highspeed motion pictures of a 1/6-scale model. The experimental restrictions imposed by exact model rules can be relieved by resorting to approximated similarity to get away from the linear scale factor of 1/6. Examples are given for a full-scale model.

In order to resolve some of the many variables associated with lunar surface vehicle design and to evaluate early analyses and assumptions, an operating model vehicle was constructed and tested over a wide range of surface conditions. The resulting test data permitted making preliminary performance comparisons of 4, 6, and 8-wheel, split-track and full-track vehicles, and predictions of prototype performance. The conflicting requirements imposed by the variable mission and surface conditions stress the necessity for an adaptable or flexible locomotion system. Common wheel or track systems which employ fixed relationships with the ground cannot provide the combination of reliability, efficiency, traction, stability, and maneuverability so important to lunar missions.