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The single point excitation procedure employed to experimentally determine the natural modes of the Space Shuttle Main Propulsion Test Article (MPTA) installed in the static firing test stand at the National Space Technology Laboratory is described. Test techniques, equipment, and associated software are described and a comparison to math model results is included. Three single point hydraulic exciters were individually used to apply random excitation forces to the MPTA thrust structure supporting the main engines. Resulting accelerations and force signals were processed with mini-computer test equipment to determine resonant frequencies, mode shapes, and damping values below 50 Hz. Two configurations, one involving empty H2 and LOX tanks and the other involving 40% full LOX tank and feed lines, were tested. Results were obtained with minimum Main Propulsion Test schedule impact and at minimum cost.

A comparison of the performance of modern modal data analysis methods on test data from the Voyager Jupiter/Saturn payload is presented. Four different test/data-analysis combinations are compared--multiple-point sine excitation tests, single-point random-excitation tests using two different techniques of manipulating Fourier transform data, and a time-domain method for analyzing random data. Results indicate that all four methods can give comparable results. Of the four, the time-domain approach detects more modes in the test data and, at the same time, shows the greatest promise for reducing the time and cost of modal testing.

This paper describes the current options for performing modal tests of spacecraft structures. Excitation options include sine dwell, sine sweep, fast sine sweep (chirp), random, initial velocity (impulse), initial displacement (twang), and ambient. Mode detection and modal tuning are discussed. Several methods of modal characterization are examined. These include tuned dwell, tuned sweep, curvefitting to frequency-response data, and time-domain analysis. Comparision of the various options are made on the basis of practical and theoretical observations as well as results of comparative tests performed on a simple structure.

Procedure of rule making in Japan, inspection for new vehicles and vehicles in use are explained. Also introduced is the abstract of Japanese Safety Regulation, Inspection Standard and Type Test Standard. Japanese Automobile Standard Organization and its brake standards is explained, mainly for commercial vehicles. Various regulations and standards are compared to show relative severity and diversion in the idea. Trend in Japanese truck, bus, trailers and their brakes were surveyed with few examples of foundation brake and components.

The design of heavy trucks with respect to the ride comfort poses two classical problems. One is the articulated vehicle problem and the other is the “jumping ride” problem caused by elastic vibrations of the frame. The two problems have been identified in field investigations. The vibration isolating system of a truck has been analysed by means of mathematical simulation. Mathematical models of different sizes have been used to examine the influence of different parameters. The damping, cab suspension and frame vibration are discussed in detail. Efforts to optimize the system have been made. These results and the results from measurements, such as impedance tests and road tests, have been applied in the development of a COE heavy truck family. The final judgement of the ride comfort of these trucks is also presented.

A full-scale vehicle testing program which emphasizes experimental determination of the rollover stability of double-bottom tanker configurations is discussed. The testing program is presented in the context of the total research program which included yaw plane and roll plane analytical studies. The baseline Michigan double-bottom tanker is found to have exceptionally low rollover stability in emergency evasive maneuvers. Vehicle modifications are described which improve stability by a factor of two. Test vehicle loading, anti-rollover outriggers, instrumentation, and modification hardware are discussed specifically. Results of dynamic handling tests and low-speed maneuverability tests are presented. Conclusions regarding the stability of individual vehicle configurations as well as overall fleet safety are reached.

Due to the high incidence of rollover in the accident experience with Michigan double-bottom tankers, a special study of rollover dynamics was included in the ad hoc study of those vehicles at The University of Michigan. A dynamic model of the vehicle in the roll plane was formulated for study of roll motions under arbitrary lateral force input time histories. The roll response and limit manuever capabilities predicted by the model were compared against that of actual vehicles and good agreement was obtained. The model was used to predict the relative rollover thresholds of the double-bottom tanker and other alternative tanker configurations for comparison to that of other commercial vehicles in a selected double lane-change maneuver. The model confirmed that double-bottom tankers of the current design exhibit a low rollover threshold in comparison to other commercial vehicles; and that certain design changes proposed as a retrofit would effectively eliminate that disparity.

A linear mathematical model is developed for studying the directional response and yaw stability of many-axled, multi-articulated tanker trucks. Analytical results obtained from the model provide an understanding of (1) the factors leading to unstable lateral responses of double tankers when only the rear compartment of the rear (pup) trailer is loaded and (2) the likelihood of rollover of the pup trailer in obstacle-avoidance maneuvers on the highway. Rigidizing the connection at the pintle hook is found to improve the directional performance of the double tanker.

Three transfer case models to improve the fuel economy of four wheel drive vehicles have been designed and developed for production. Improved economy is obtained by (1) minimizing churning and friction losses for highway made two wheel drive operation, (2) minimizing the weight of the transfer case assembly, and (3) providing low range transfer case ratios compatible with the lower numerical axle ratios demanded for highway fuel economy.

CAFE (Corporate Average Fuel Economy) requirements were authorized for both “Cars” and “Light Trucks” as a result of the “Energy Policy and Conservation Act” of 1975. This paper addresses the methods by which fuel economy may be increased by design efficiency of Light Trucks in consideration of legislated goals and considers aerodynamic and road load improvements, weight reduction, powertrain selection, and optimization. In selecting the optimum fuel efficient design, adequate consideration must be given to emissions, structural durability, performance constraints, and consumer acceptance and not to forget manufacturing constraints and lead time considerations.

This paper will discuss four wheel drive vehicles of today and tomorrow. It offers those in the light truck industry an awareness of fuel economy challenges and an insight into meeting them. Broad in scope, the text touches on many areas of relevance to vehicle fuel economy. It is concerned with the drive systems of four wheel drive vehicles from the light truck industry and written in the qualitative rather than quantitative style. First, a definition of four-by-four vehicles is provided and then the explanation of the drive systems they use. Next, the paper will cover: 1) Changes in the four-by-four market; 2) the effect of federal regulation on four wheel drive vehicle manufacturers; 3) an overview of E.P.A. fuel economy testing; 4) suggestions for reducing vehicle fuel consumption; and 5) a prototype of a fuel-efficient four wheel drive vehicle.

A numerical method has been developed to solve the steady three dimensional Reynolds-averaged Navier-Stokes equations by successive approximations. The method is applicable to rotors of axial or radial compressors and turbines. Viscous flow fields were calculated in the blading passages of an axial supersonic compressor cascade, a radial impeller and a backswept impeller. Pressure measurements on the cascade blades agreed with corresponding computations. Radial impeller calculations showed suction blade separation, while backswept calculations indicated shroud separation. This paper describes the numerical method in detail, with results presented as numerical examples.

The unique character of Naval Aviation is evident in the aircraft carrier and low level overwater operations. The Navy's training system embraces this uniqueness as well as the more familiar aspects of flying in preparing both fledgling and experienced pilots to step into the fleet cockpits. The system has evolved over many years from a generalist approach to one of more specialized expertise. The process of primary weapons system design and procurement is now recognizing the necessity for early consideration of training requirements. Recent developments forecast an emerging system designed from the ground up for pilot training.

It is known that capacitance-sensing, rotor-blade-tip-clearance measurement systems suffer from a strong dependency on probe tip temperature and humidity. A novel in-place recalibration technique partly overcomes this problem through a simple modification of the electronics that permits a scale factor correction. The technique is used to reduce the errors in a commercial system by more than 50 percent up to a temperature of 370° C (700° F). A probe design is proposed to further raise the maximum temperature capability of the measurement system.

Four studies investigating the effectiveness of flight simulation training are presented. They were selected on the basis that they illustrate the training effectiveness methodology currently employed, and that they demonstrate the potential value of simulation training. These four efforts address: (1) the training effectiveness of platform motion; (2) the relative effectiveness of alternate visual systems; (3) the effectiveness of generalized surface attack training; and, (4) the effectiveness of A-10 simulation training. These studies are discussed in terms of implications regarding required levels of fidelity as well as the potential value of the training.

This paper discusses the resources that must be considered when determining the costs of pilot training systems. Material presented here is based on the authors' experience in estimating the cost of current and advanced Pilot Training Systems. The paper examines how system requirements, such as number of students, attrition rates, course syllabi, and maintenance concepts impact training system personnel and equipment cost. The discussion also shows the sensitivity of pilot training cost to variations in training system requirements and hardware characteristics.

Evolved from a research tool, the first of a family of very-low-cost part-task training devices is now being developed and will shortly enter an evaluation phase. Key to the low system cost is use of a minicomputer and graphics display in a small, stand-alone cabinet. Training features are concentrated in software, stored in a library of diskettes. Low cost and portability of systems should lead to wider availability of refresher training and consequent increases in readiness and safety.

The US Army's Aviation Training Research and Development Program is discussed in this paper. An overview of the research program concept is presented, with special emphasis on the behavioral research required to enhance aircrew performance. The overview is followed by discussions of representative research in the areas of tactical flight training, flight simulation, and aviator selection and assignment. The discussions emphasize the user orientation of the research and development and project the advanced techniques and trends in training and equipment.

The operational and economic environments associated with agricultural aircraft have dictated several changes to basic turbine engine installation procedures. As the ingestion of chemicals can cause rapid distress in the engine hot section, intake systems are proposed. Aircraft missions are analyzed, and the effect of high cycle time on major rotating components explained. In addition, with jet fuel seldom available at remote fields, alternates such as diesel and gasoline - together with their limitations - are dealt with. Operational data is reviewed, recent studies and developments outlined, and the future of the gas turbine engine in agricultural aircraft discussed.

Aircrew Performance Measurement is emerging from a research venture into the realms of developing technology. Initially the technology is being developed for the quantitative assessment of undergraduate pilots flying skills as they transition from training airplanes to the more sophisticated operational types. The universal approach to the system development will enable similar equipment and mechanizations to be used on all airplane types and furthermore to the quantitative measurement of aircrews for certification renewal purposes.