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A brief summary is presented of general fatigue characteristics of low-shear transfer aircraft joints and discussion of some improved fastening systems for providing fatigue and sealing redundancy of these joints.

The Navy is currently in the second phase of a program to develop a supersonic turbojet engine for tactical missile applications. The engines have been designed for a single mission only and for lowest possible cost. Three companies (AiResearch, Curtiss-Wright, and Pratt & Whitney Aircraft) are under contract to fabricate and test the critical components of their respective engine designs. Each engine is described with emphasis on its low cost design features and fabrication techniques. The overall program status and available results of the current critical component phase are presented. Design requirements and problems unique to expendable turbine engine development are also discussed.

The maturing air transportation industry is finding profitability to be increasingly elusive. The cost of maintaining aircraft has a substantial impact on profitability. It is incumbent on aircraft and system designers to minimize the cost of maintaining those aircraft to maximize profitability. Choosing mature components and systems that have demonstrated reliability, are familiar to maintenance personnel, and for which spare inventory exists, is an effective technique for minimizing maintenance costs of a new aircraft. This paper discusses examples of such applications and describes the values that can result.

A new approach to estimating manufacturing cost at the part level is described. This method is based on material specifications, weights, and other material parameters. The parts price estimating model is explained in terms of the data base, which includes such items as labor cost, material cost, manufacturing cost, material specification, part form, and weights. The model is then developed according to the type of input data available.

When United Aircraft Corp.'s JT15D engine was first considered for potential high-altitude, low flight speed, long-endurance RPV applications by the U.S. Air Force, the questions were: 1. Will the engine run at these altitudes? 2. Can it deliver the required thrust? 3. Can it deliver the required power extraction? 4. What is the specific fuel consumption? 5. What oil system modifications are needed? 6. What is the optimum control system? 7. Are there other unknowns? A JT15D-4 turbofan engine, with only minor modifications which were easily incorporated into engines coming off the production line, proved more than adequate to achieve predicted endurance goals and measured performance.

This paper describes the recent and successful features of the intensive program at Detroit Diesel Allison, Division of GMC, to control the costs of advanced military aircraft gas turbine engines in line with the costs of current production engines and of those produced during the past several years. We have been attempting to incorporate highly advanced technology into our new products, while at the same time holding the costs in line with older technology products. In many instances, we have been able to use the advanced technology to lower costs at the same time that weight and performance are improved. There are examples of this in aerodynamics, mechanical design, and materials and processes.

The 1500 SHP T700 Engine is being developed for the U.S. Army UTTAS and AAH Helicopters. Prototype engines have been running well since testing began early in 1973. Qualification is expected in early 1976. Engine history and current details, design features, program milestones and possible future developments are reviewed. The unique T700 design will achieve unusually high levels of reliability and maintainability.

The exhaust from a high bypass ratio turbofan engine, passing over the upper surface of a wing and trailing edge flap system, can be deflected by the Coanda effect to create both deflected thrust and supercirculation. This technique, known as “upper surface blowing,” has been applied to the U.S. Air Force/Boeing YC-14 advanced medium STOL transport airplane. Laboratory and wind tunnel tests have shown very efficient turning of the jet flow, large values of supercirculation, and excellent boundary layer control of the external flow on the upper surface of the wing. This combination creates a powered lift system having unusual efficiency and versatility.

The YC-15 will be the first aircraft to employ the externally blown flap (EBF)-powered lift system. Since the success of the aircraft to a large extent is dependent on the proper functioning of this system, considerable effort is going into its design. The present paper discusses some of the fundamental aerodynamic considerations which led to the selection of the specific flap configuration and presents resulting aerodynamic characteristics. Structural design criteria for the system and methods of analysis are covered, as are details of the flap-actuating system and structure.

The LTS 101 has been designed to meet the requirements of low cost, high performance, and simplicity in a powerplant suitable for a variety of applications in the 600 shp class. This paper discusses the parametric cycle studies that led to integration of the LTS 101 aerodynamic components to achieve these goals, and presents results of full engine prototype tests. Design features that contribute to the low cost of ownership are described.

The Space Shuttle Main Engine is a reusable, high-performance rocket engine being developed by the Rocketdyne Div. of Rockwell International to satisfy the operational requirements of the Space Shuttle Orbiter Vehicle. The design incorporates a hydraulically actuated, closed-loop servosystem controlled and monitored by a programmable electronic digital controller. The controller accepts vehicle commands for the various engine operational phases, positions the appropriate valves, monitors the engine for the required performance precisions and conditions, and provides redundancy management.

The Space Shuttle Orbiter vehicle employs two earth storable bipropellant propulsion subsystems to provide orbit maneuvering and vehicle attitude control. Respectively, these are the Orbit Maneuvering Subsystem (OMS) and the Reaction Control Subsystem (RCS). The OMS provides the velocity increments necessary to achieve final insertion of the vehicle into earth orbit, to perform orbital changes, and to de-orbit the vehicle. The OMS is made up of two normally independent propulsion subsystems in removable pods. Each contains a 6000 lb. thrust rocket engine, propellant tankage, and necessary feed and control componentry. The propellant capacity of 24,721 lbs. for both pods provide a nominal 1000 ft/sec velocity increment. In addition, a supplementary propellant supply, the cargo bay kit, boosts the all-up delta V capability to 2500 ft/sec.

This paper presents the metric program approach taken by the Boeing Aerospace Co. in the design and fabrication of the PHM hydrofoil ship. The program approach was to maintain a strict metric base line allowing exceptions only where extensive qualifications, schedule impact, costs, and reductions of performance were imposed by a metric design. The program metric implementation plan is described. A discussion is provided of the metric problems encountered and the solutions evolved. The PHM ship evolves as a hybrid design where the structural design is metric and some of its operating systems are inch designs. An analogy is made relating the approach to more sophisticated aerospace-type programs as spacecraft, aircraft, etc. The analysis is made on the basis of a need for additional aerospace quality engineering metric standards in order to produce a complete metric design.

The Heavy Lift Helicopter (HLH) is the airborne component of a container ship and helicopter logistics system. The U.S. Army initiated a program for development of advanced-technology components (ATC) for the HLH in June 1971 to reduce the risk associated with future procurement of an air vehicle. The components now under development by Boeing Vertol include the rotor and drive systems, flight-control system, and cargo-handling system. In addition, Boeing Vertol selected and procured representative HLH engines for use on an integrated rotor- and drive-system test rig. The HLH program has now been extended to include construction and flight-test demonstration of an austere prototype aircraft to evaluate the ATC components in a dynamic environment.

Computer graphics has become the bridge between the computer and the designer. McDonnell Douglas' CADD system was originally developed for parts layout and solutions to geometry problems, and this restriction was maintained until recently so development could be controlled. Now, with the maturing of the system, several disciplines are converting the computer graphics design package to their special applications. Recent advances in computer graphics software have been adapted to advanced design. The integration of these disciplines has required a number of changes in design techniques in order to evolve and evaluate a conceptual configuration. However, the time savings alone will allow advanced design teams to define and analyze more configurations earlier in the design cycle, resulting in much greater design visibility and with greater accuracy.

The general characteristics of flutter problems affecting the structural design of both subsonic and supersonic transport aircraft are discussed in relation to configuration constraints resulting from mission performance and environmental impact requirements. Combined analytical and experimental approaches employed in the assessment and solution of these problems are outlined. Included are discussions of the extensive application of automated procedures in the use of high-speed digital computers for flutter analysis and the dependence on highly sophisticated wind tunnel flutter model construction techniques to provide reliable experimental data. Illustrations of the application of design techniques to supersonic and subsonic aircraft are presented.

Machinery maintenance programs based on vibration trend monitoring have been successfully used in several applications. In essence, these programs rely on the interpretation of changing machinery vibration patterns to diagnose developing defects and subsequently define a relative condition index. This information, along with other operating parameters and constraints, is then used to draw up meaningful maintenance schedules. This paper, after a brief review of the vibration monitoring programs in use by the Sea Element of the Canadian Armed Forces, discusses the operational problems that arise in the definition of a vibration health monitoring program for a 750 kW gas turbine generator. It describes in detail the rationale for selecting the location of points where measurements should be made and lists the mechanical components which influence the vibration pattern at each station.

Recent advances in the design and development of motion simulators, visual display systems, artifical force producers, and computer capability have enhanced the effectiveness of ground-based simulators in the design process. At Northrop, a systematic improvement in simulator subsystems has resulted in the existence of the Northrop Large Amplitude Three-Axis Flight Simulator which has 6 degrees of freedom. The simulator is a significant tool in the design of flight control systems, particularly in today's environment where the aerospace industry is attempting to extend the performance envelopes of its products through the use of nonconventional configurations and radical flight control system concepts. Some examples are presented in this paper to demonstrate the contribution that the Northrop Large Amplitude Three-Axis Flight Simulator is making in the YF-17 program to the solution of current flight control system problems that are not soluble by analytical techniques.

Predominant features of sound signatures can be related back to operational events occurring within components both for normal and failure mode operations. Engineering analysis permits establishment of quantized go, no-go, or caution parameters necessary to make readiness assessment decisions. The “Structure Borne Acoustics” test technique presented in this paper has outstanding potential for this work. Reliability includes accurate detection and diagnosis of the maximum number of faults, with an absolute minimum false alarm rate. Jet engine-bearing monitoring is one example of successful application.

A technique is discussed for generating diagnostic information from the vibration signature of machinery in the high-frequency range (up to 100 kHz). The signal generation mechanism is discussed, as well as the diagnostically significant characteristics of the data and a method of extracting this information. Two specific cases are presented utilizing the techniques to illustrate its suitability for many of the common problems encountered in machinery.