Search Results

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.

Due to rising under-the-hood temperatures and the trend in industry in general for longer life products, the long-term heat resistance of elastomeric materials is generating considerable interest. This paper reviews some of the compounding techniques necessary to develop the best long-term heat resistant epichlorohydrin compounds. The long-term (1000 hrs.) aging resistance of these materials will be compared to more conventional materials such as CR, NBR, CSM and EPDM compounds. Also blends such as Acrylate/Epichlorohydrin and Epichlorohydrin/Chlorobutyl will be reviewed as ways to obtain a balance of heat resistance and cost.

Butadiene-acrylonitrile copolymers have been the preferred general purpose oil and fuel resistant elastomers in automotive, aircraft and industrial product applications for over 30 years. The need for improved service performance to meet more severe and/or newly emerging service requirements has prompted a number of studies to improve the performance of these polymers. This work has led to the development of a family of new and unique polymerization bound antioxidant stabilized nitrile rubbers which have outstanding heat resistance characteristics. These new rubbers also retain their age resistance qualities after exposure to oils or fuels which can extract the protective antioxidants from conventional nitrile rubbers thereby contributing to early failure of parts in service.

The stresses arising in a vehicle structural part during the operation period could be divided into three essential components. The extreme values of these components and their distribution function may be derived. Using appropriate crack propagation functions one can define the momentary service strength of the structure and the damage-function. On the basis of the new fracture model presented, the life distribution can be interpreted unambiguously. By using certain assumptions, the deverage value and the scatter of the life can be derived. The new fracture model allows the several fracture types, like static, pure dynamic, pure fatigue, and general fractures to be treated on the same basis.

A case study describes a fatigue damage analysis of a light truck frame. The objective of the analysis is to determine whether an existing frame design can safely accept a ten percent increase in load. The analysis, completed in less than a month, incorporates an experimental stress-strain analysis, proving ground test data and experimentally determined properties of the frame material. Three common methods of damage analysis and a relatively new procedure are compared and the advantages of the new method are demonstrated.

Fly-By-Wire offers the designer flexibility in mechanizing the manual flight control system and makes possible potential CCV performance benefits because more complex functions can be implemented. The full potential of FBW and CCV can only be achieved by incorporating these concepts in the initial design phase of a new airplane. Greater benefits are obtained in several areas when applying FBW and CCV simultaneously.

An exploratory definition study has been conducted for an Advanced Fighter Digital Flight Control System. The principal objective was to derive and evaluate custom multimode control laws, related displays, and multichannel digital fly-by-wire implementation schemes for advanced Air Force and Navy fighters. Study results show that a triplex flight control system provides the lowest weight, the best maintainability, and the lowest cost of the candidate configurations considered. Results also indicate that mission-oriented flight control laws integrated with compatible displays and controllers can provide enhanced mission effectiveness and reduced pilot workload. It is recommended that the concepts analyzed and simulated during this definition study be implemented and evaluated by flight testing.

The design and operation of highway trucks in Europe is subject to legislation which is more detailed and restrictive than in the United States. The operating environment and consequently the market preferences frequently differ from those in North America. This paper discusses the important European legislation and marketing factors affecting truck design and describes the major features of a new range of heavy duty trucks designed primarily for operation in Europe. Some of the differences between European and North American highway trucks are also reviewed.

Approaches to the development of improved high temperature engine materials are reviewed. Emphasis is placed on emerging materials technologies and their potential benefits to aircraft gas turbine engines. Advances in materials processing technology are considered also, with emphasis on areas of potential cost reduction. This review also examines a changing approach to the selection of turbine engine materials technologies for future development. This changing approach places greater emphasis on the overall economic benefits to the aircraft system rather than improved engine performance.

A discussion regarding experiences with integrally-cast compressor and turbine components during fabrication and testing of four engine assemblies of a small (29 cm (11½ in.) maximum diameter) experimental turbojet engine design for an expendable application is presented. Various operations such as metal removal, welding, and re-shaping of these components were performed in preparation of fulls-cale engine tests. Engines with these components have been operated for a total of 157 hours at engine speeds as high as 38, 000 rpm and at turbine inlet temperatures as high as 1256 K (1800° F).