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This paper describes the results of the first step of a planned development program to produce a family of split path hydro-mechanical transmissions for military applications. The HMT-250 hydromechanical transmission has given superior performance, unlimited ability to change ratio without affecting service life, and a control system with the advantages of variable ratio. The control system and testing programs are described in detail.

An organic Rankine Bottoming cycle added to Diesel engines used for long-haul trucks has the potential of improving their peak fuel economy by up to 15% over a typical duty cycle. General Electric has developed a multi-vane rotary expander which has a measured isentropic brake efficiency of 80+% over a wide range of speed and power levels with organic working fluids. High cycle efficiency for design and off-design conditions is achieved with the multi-vane expander. The potential advantages of the multi-vane expander for the Diesel engine bottoming cycle include the elimination of a high speed gear box and the potential for over 80% isentropic engine efficiency. The multi-vane expander is a ruggedly built component running at Diesel engine speed. This paper describes the design and evaluation of a nominal 40 HP multi-vane expander for this application.

Alternative engine concepts to the advanced high bypass turbofan which have promise of reducing energy consumption including regenerative cycles and other engines with heat exchangers, unconventional engine arrangements such as geared fan engines, and high disc loading turboprops. After initial screening, several concepts were selected for a systematic evaluation of the merits of each relative to a high bypass turbofan based on advanced technology consistent with the mid 1980's time period. Both mission fuel and direct operating cost for typical long range transport missions were considered in the evaluation.

EXPERIMENTAL RESULTS are presented for the effects of water in #2 diesel fuel emulsion on engine performance and combustion for a two cylinder laboratory engine of GE-7FDL series diesel engine parameters. Smoke, NOx, and CO emissions were decreased as the water amount in fuel was increased. At the maximum tested amount of about 30% water, smoke reading was reduced by half (Bosch number) and NOx reduced by 50% at full load. Fuel consumption can be lowered somewhat by adding water also. The potential of fuel savings is about 1-2%. it is more at the lower intake pressure notch 5 load than notch 8 load with higher intake pressure. Both emissions reduction and fuel saving were realized at the expense of increased engine running roughness.

Previous studies had demonstrated the economic and technical feasibility of producing high-quality forgings for aircraft turbine engine parts from hot-isostatically pressed (HIP) Rene 95 powder billets. The present program was aimed at developing a production practice for making HIP + forged turbine discs. The major goal was improved product fabricability and reliability with minimum cost. The program was conducted using argon atomized Rene 95 powder. Experimental studies were conducted to evaluate the effect of powder characteristics, HIP parameters, preform design, and forging conditions on forgeability, microstructure, and mechanical properties. The results of these studies were incorporated into a pilot production run in which 10 disc forgings were made and evaluated. The selected process involved the consolidation of -60 mesh powder to full density by hot-isostatic pressing at a temperature above the γ' solvus temperature.

The advantages of infinitely variable ratio steering and propulsion for track laying vehicles are well known. Studies and demonstrator programs in the past decade have indicated that the hydromechanical transmission has the most promise of providing infinitely variable ratio for military vehicles. In 1966 the Army launched a program to develop the hydromechanical transmission to “production ready” status. This paper describes that program, the transmission selected, and some of the problems encountered in the transition from the demonstrator stage to one of readiness for military application.

THE problem of this study was: 1. Can a method of analysis be found which adequately predicts the heat-transfer and cyl-wall temperature phenomena in diesel engines? 2. Are there criteria for the design of diesel engine cyl that give the limits of reliable practice as found in typical diesels? Such a method of analysis is detailed in this paper. Design criteria were also found which appear applicable to broad classes of diesel engines. It was determined that the method was useful in prediction of the thermodynamic performance of a diesel insofar as the influence of cyl heat transfer on efficiency, power, and cooling load were predictable.

THE CONCEPT of an electric motor mounted inside the rim of a large wheel provides several advantages: flexibility, weight and cost reductions, and adaptability to established operating and maintenance patterns. A heavy-duty traction motor drive has been designed that eliminates the need for mechanical drive lines, differentials, and hydraulic torque converters. This paper describes the gear train, lubrication system, brakes, and ventilation of such a drive. Also discussed is the engine-generator set for an electric wheel motor.*

Installation considerations for high bypass engines in the range of 5-10 are examined. An engine and installation concept for the high bypass is described. Installation considerations discussed include the effects of nacelle shape, wing proximity, inlets, thrust reversers, and accessory location. It is pointed out that the high bypass engine may offer the flexibility to design the ideal aerodynamic installation without compromise by installation requirements.

Measurement of dimensional characteristics of airfoil parts is primarily a manual, labor intensive operation. It employs a wide variety of gages that vary from very expensive optical comparitors to inexpensive pin gages. An automatic non-contacting inspection gage capable of measuring most dimensional characteristics would be cost effective, simplify inspection operations, consolidate a number of gages into one, and improve overall inspection reliability by minimizing human involvement. This paper presents the results of the design and development of a demonstrator semi-automatic laser gage dimensional inspection system that addresses this problem.

This paper describes how the SP-100 Space Reactor Power System (SRPS) can be tailored to meet the specific requirements for a lunar surface power system to meet the needs of the consolidation and utilization phases outlined in the 90-day NASA SEI study report. This same basic power system can also be configured to obtain the low specific masses needed to enable robotic interplanetary science missions employing Nuclear Electric Propulsion (NEP). In both cases it is shown that the SP-100 SRPS can meet the specific requirements. For interplanetary NEP missions, performance upgrades currently being developed in the area of light weight radiators and improved thermoelectric material are assumed to be technology ready in the year 2000 time frame. For lunar applications, some system rearrangement and enclosure of critical components are necessary modifications to the present baseline design.

A new silicone rubber formed-in-place gasketing concept has been developed which has greatly reduced the incidence of warranty oil leaks in engine and drive train components. This concept utilizes a combination of joint configuration and unique cured properties of the silicone formed-in-place gasketing material to achieve leak-free performance over the life of the component.

All of the properties of the materials used in the design, analysis, and manufacture of jet engines are listed in the seven-volume Material Properties Handbook. Keeping these volumes of curves up-to-date has been a constant challenge, but recently work began to replace the old system of printed volumes with a computerized record that can be accessed from virtually anywhere. This paper is a status report on the project.

The General Electric Company has recently been in the process of developing two new turbofan aircraft engines-the TF34 and the F101. The TF34 has been developed for the U.S. Navy's S-3A antisubmarine warfare aircraft and has been selected by Fairchild-Hiller for the U.S. Air Force A-10A; the F101 is being developed for the U.S. Air Force B-1 strategic bomber. Each of the new aircraft programs has the common requirement for subsonic endurance. The S-3A and A-10A requirements include subsonic operation only while the B-1 includes supersonic capability as well as subsonic. This basic mission-mix difference combined with major differences in engine/air vehicle installation features and different levels of technology applied due to the relative chronology in the respective development programs leads to contrasts in the design features of the major components of the engines.

The problems and choices in the design of an advanced subsonic transport turbofan for reduced noise and improved aircraft performance are examined in this paper. The effects of bypass ratio, fan pressure ratio, and fan tip speed on jet noise, fan noise, and acoustic treatment suppression are described. The results do not indicate a clear optimum bypass ratio considering the effects upon installed engine performance and weight as well as acoustic performance. Low fan tip speed designs with the associated high aerodynamic loading are compared to high tip speed low loading designs. Other factors affecting noise such as the installation and other noise sources are discussed. The long duct installation is indicated to have potential advantages over the short duct separate flow installation. The problem of assuring that growth models of an engine also have low noise is discussed.

THE “Orion” gas-generator turbocompound engine consists of a supercharged, regenerative aircooled, 2-stroke-cycle opposed-piston diesel engine driving two centrifugal compressors. One of these compressors is for combustion air with fine air filtration, while the other is for cylinder cooling with much less filtration. The gas-generator engine has a bore of 4¼-in. diameter and a stroke of 5⅞ in. × 2. The engine turns at 2340 rpm, and the combustion air compressor turns at 37,000 rpm while the cooling air compressor turns 17,000 rpm. The cylinder is cooled with air at nearly the supercharge level and at an equivalent temperature because this air later does work on the turbine. The cooling airflow is about 3½ times the combustion airflow. These two airstreams join in a plenum chamber downstream from the engine, and the mixture temperature is about 500 F. This hot gas stream then goes to the power turbine, which is mechanically free of the gas generator.

The analysis of exhaust gas is becoming an increasingly important tool in determination of the performance of high temperature combustion systems. Previous methods involving the collection of gas samples in sampling tubes, followed by subsequent laboratory analysis, have been laborious and time consuming. A new on-line gas analysis system has been put into service, which makes a complete analysis every 30 sec directly at the test site. The system involves the use of five process gas chromatographs to measure oxygen, nitrogen, carbon dioxide, carbon monoxide, and hydrogen, plus a hydrocarbon analyzer to determine unburned hydrocarbons. These measurements in conjunction with other operating data permit the calculation of overall combustor performance, as well as identification of local point-by-point conditions at the combustor exit.

The principal design features of the NASA QCSEE UnderThe-Wing and Over-The-Wing powered lift propulsion systems are given. In the UTW engine, these include noise reduction features, a variable pitch low pressure ratio fan, a fan drive reduction gear, an advanced core and low pressure turbine with a low pollution combustor, a digital control, and advanced composite construction for the inlet, fan frame, fan exhaust duct, and variable area fan exhaust nozzle. The OTW engine is similar but has higher fan pressure and a fixed pitch fan. Both engines are scheduled to be fabricated and tested starting in 1976.

An acceleration of metal replacement to reinforce thermoplastic composites is positioned to impact the transportation markets through a joint venture between PPG Industries and GE Plastics, called AZDEL, Inc. The strength of both companies' strong technological base in glass and engineering thermoplastic resins is the key. The resulting long continuous glass thermoplastic composites have high strength to weight ratios, provide tough durable products, facilitate combining functions in design, and because of its high speed manufacturing processes, is cost effective. In addition, these materials can be post fabricated during the assembly phase, easily repaired and conveniently recycled. Value added secondary operations for both the captive or custom molders provide another avenue for cost reductions.

Reliability can be improved by the careful definition of the mechanical properties of engineering materials. Methods to define these properties for design functions by the use of statistics and probability concepts are presented. In addition, methods will be presented for quantitatively measuring the effects of specification screening on the improved properties of the acceptable materials. By selection of the proper design allowables based on required failure rate, reliability can be designed into components using the techniques discussed and illustrated.