Search Results

The purpose of this paper is to introduce the DYNALIST (Dynamics of Articulated Linear Systems) computer program and demonstrate its application to rail-vehicle systems. The program is available through the U. S. Department of Transportation, Transportation Systems Center, and offers general modeling and computational tools for linear analysis in the frequency domain based on modal superposition. The paper describes the lateral dynamic analysis of a passenger-type vehicle including calculations for sinusoidal, periodic and stationary random rail irregularities. A transient response capability is also demonstrated. Approximate results based on modal truncation are compared to exact solutions.

The linear induction motor research vehicle (LIMRV) recently set a world speed record of 255.7 mph for steel-wheel-on-steel-rail vehicles during a series of test runs conducted on the 6.2 mile-long experimental track at the Transportation Test Center, Pueblo, Colorado. This paper presents performance data on LIMRV dynamics associated with acceleration, steady-state operation, and braking, as recorded during these tests. Actual test results are compared with analytical predictions. Difficulties encountered are discussed and their solutions described.

Current gas turbine fuel controls for unmanned applications usually employ electronic computation controlling a basic fuel handling package. Several possible fuel handling systems are discussed, and examples of a simple target drone control and more complex cruise missile control are described in some detail. Finally, some comments are made on likely future trends in electronic computer design.

Experimental results are used to explore the physical mechanism of lift augmentation and the drag due to lift, and to show the inadequacies of the Taylor-Spence thin jet model of the jet flap. In the jet-flapped wing-fuselage configuration, 3D effects, particularly due to the wing-fuselage interference, are shown to have major effects on the performance of the jet flap. At large sweeps the 3D vortical nature of the shock-induced separation is shown to also play a dominant role.

Jet flaps, because of their propulsive lift characteristics, have the theoretical potential to improve fighter aircraft performance. Studies have shown that to achieve these improvements afterburning jet flaps are required. The benefits gained are primarily at high lift coefficients; consequently, there is a significant interaction between the jet flap effects and the wing aerodynamics. In order to integrate the jet flap into fighter designs, short afterburners are necessary. Titanium sandwich construction appears to be the best structural concept for a jet flap.

A wide variety of potentially useful and effective airbreathing aircraft have been postulated to operate at speeds in excess of Mach 3.0 by NASA and the USAF. These systems include hydrogen-fueled transports of interest for very long ranges and airbreathing launch vehicles which are aircraft-type first stage candidates for future space shuttle systems. Other high speed airbreathing systems for possible future military applications include advanced reconnaissance and figher/interceptor type aircraft and strategic systems. This paper presents (1) a chronology of Air Force technical activity on future propulsion concepts, (2) a status report on NASA research on scramjet technology for future systems which may require speeds above Mach 5, and (3) a description of a research vehicle by which advanced propulsion technology and other technologies related to high speed can be demonstrated.

The TRW Low NOx Burner was conceived and developed utilizing the substantial technical expertise acquired during development and production of combustion systems for rocket engines and auxiliary power units. The Low NOx Burner is based upon hydraulic and injection principles derived from the design of the Lunar Excursion Module lander rocket engine. This engine required high combustion intensities, turndown ratios and manned flight reliability. Using these basic principles, TRW has patented, developed and commercialized power burners which have demonstrated reduced pollutant levels and high thermal efficiencies. Gas, light and heavy oil burners firing over a 2 to 55 MBtu/hr have been developed and field tested. The TRW activity has also been expanded into demonstration programs to demonstrate similar performances and low emission levels in utility type boilers.

A study was made of desirable advanced fighter technologies for integration into a demonstrator aircraft which would be used to evaluate combat effectiveness. The demonstrator aircraft configuration development is traced, and its physical and performance characteristics are summarized. The technologies incorporated are described and their performance characteristics and benefits are discussed and substantiated by applicable wind tunnel or manned simulation results. Key technologies include: advanced aerodynamic configuration, advanced structural concepts; integrated maneuvering nozzle, variable incidence outer wing panel, variable camber, chin fin, multi-mode digital fly-by-wire control system, integrated fire fire control system, and high acceleration crew station.

The paper presents some of the problems encountered when advanced technology hardware and/or software are made a part of an ongoing system such as the B-1 bomber. The introduction of diffusion bonded Titanium, superplastically formed parts and the use of boron reinforced longerons are three examples of new technological applications of hardware. The requirement to conduct a fracture mechanics control program, the new computer program to determine the combination of the fatigue effects and fracture behavior and a new flutter optimization methodology are three other examples of new applications of software to a military aircraft. The paper treats each example to show why it was adopted, the pressing need to make it work in the real world outside the laboratory and some of the problems of using the new technology which were not anticipated.

The Advanced Fighter Technology Integration (AFTI) program was conceived to provide the mechanism for orderly transfer of Air Force technology programs into operational systems. This paper presents the results of the McDonnell Aircraft Phase I AFTI study, which involved identification of high-payoff, mature technologies, the integration of these technologies into effective operational configurations, the design of manned demonstrator aircraft, and the validation of a selected concept through wind tunnel tests and manned simulation. The Phase I study verified the program premise that fighter/attack aircraft with greatly improved effectiveness are achievable with recently emerged technologies, if these technologies are integrated during the conceptual phase so that they literally shape the vehicle. The Vectored Lift Fighter (VLF) is such a concept, employing new flight and control modes.

The technology requirements for new subsonic transport engines which might go into service in the mid 80's are discussed with the emphasis placed upon improving energy consumption and aircraft economics. A typical advanced turbofan engine is described. Effects of variations in major cycle parameters on fuel usage and direct operating cost (DOC) of advanced aircraft designed for 0.8 Mach no. are shown. The impact of specific engine design and technology features including component aerodynamic and mechanical improvements, high temperature materials and cooling, composites, and advanced nacelle designs is also shown and related to the technology advances required.

The concerns for limited availability of petroleum based fuels and the upward cost spiral of oil has resulted in great interest in fuel consumption in the aviation sector of transportation. NASA has conducted studies to identify and accelerate the development of promising advanced technologies appropriate for achieving fuel conservative aircraft for the next generation of commercial transports. Several advanced technologies in the airframe and propulsion disciplines have been identified by NASA, with the turboprop being one of these. Two decades of turboprop technology advances are discussed along with their application to a Prop-Fan propulsion system for modern high-speed commercial aircraft. The Prop-Fan propulsion system features a small diameter, multibladed propulsor geared to an advanced gas turbine engine.

Air Force design criteria have been published for the pressurized hydrant fueling system, and the philosophy and operation of a typical system is described. The use of non-corrosive pipeline materials and the internal coating of storage tanks have contributed significantly to maintaining a high level of quality for aviation fuels. Experience with the use of fiberglass reinforced plastic pipe is discussed.

Variable Cycle Engines being studied for advanced commercial supersonic transports show potential for significant environmental and economic improvements relative to 1st generation SST engines. The two most promising concepts are: a Variable Stream Control Engine and a Variable Cycle Engine with a rear flow-control valve. Each concept utilizes variable components and separate burners to provide independent temperature and velocity control for two coannular flow streams. Unique fuel control techniques are combined with cycle characteristics that provide low fuel consumption, similar to a turbojet engine, for supersonic operation. This is accomplished while retaining the good subsonic performance features of a turbofan engine. A two-stream coannular nozzle shows potential to reduce jet noise to below FAR Part 36 without suppressors. Advanced burner concepts have the potential for significant reductions in exhaust emissions.

A noise measuring program during the running of flat-track races for 750-cc, four-stroke, twin-cylinder competition motorcycles showed that the noise measured under actual track conditions correlated fairly well with the American Motorcycle Association's (AMA) 4,000-rpm static test method of predicting noise. Equations are presented that, if substantiated, can be used to accurately forecast from the AMA static test results the noise levels that will be generated during such events. The motorcycles, equipped with mufflers, projected significantly fewer decibels into the local community than local officials had deemed objectionable. However, the racing cyclists and their pit crews experienced noise levels loud enough to cause permanent irreversible hearing damage.

New OSHA requirements regarding the use of VCM (vinyl chloride monomer) have been found to present specific problems with certain sampling methods and analytical procedures. This report will attempt to define some of these problem areas.

Two recently developed sheet products offer material cost savings opportunities of approximately $2.50 per typical car with catalytic conversion system. Galvalume sheet steel, an aluminum-zinc alloy coated sheet, has been used successfully for grass shields replacing type 1 aluminum coated sheet at an approximate savings of 25¢/lb. Chromized sheet, which has a diffused layer of ferritic stainless steel on both surfaces of a special low carbon sheet, is suggested as a substitute for 400 Series Stainless Steel at a material cost benefit of approximately 15¢/lb. Exhaust inlet tubes and convertor shells of Chromized have been successfully tested.

It is recognized that stratified charge combustion in a spark ignited internal combustion engine can produce improved fuel economy. A historical summary of many significant patents and articles is given pertaining to the 3-valve form of this engine combustion principle. The present social need of reducing exhaust emissions, and the renewed goal of improving fuel economy, makes this engine form one practical approach to the “clean engine” being sought for vehicular use. It uses a rich prechamber charge to provide the proper stratification. The prechamber can vary considerably in size depending upon the goals sought and the engine application. A basic requirement is that the fuel-air equivalence ratios of the charges in the two combustion chambers are within certain limited ranges to achieve proper optimization. The ratios should be 15% rich for the prechamber and 15 to 30% lean for the main chamber at the moment of ignition.

Fantastic changes are taking place in our use of resources and in our life style. The industries that supply raw materials are being bombarded by demands. All are interrelated, and to fix one problem aggravates another. This paper discusses solutions to these problems, solutions which will require more material substitution for a given application. These solutions will require our technological society and government regulations to adjust to new systems to find an adequate resolution.

Simplified curves and equations are developed that can be used to predict the vibration level of a supporting structure from the action of the various vibration sources of a slider-crank mechanism. Using a chain saw as an example, the vibration levels from each major vibration source are presented goether with the vibration level with various isolation stiffnesses as presently used in practice. The vibration levels are reviewed to determine the design parameters necessary to meet a 0.5 “g” specification, and a novel isolation concept is presented together with actual vibration spectrums.