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Understanding the friction behavior of brake lining materials is fundamental to the ability to predict brake system performance. Of particular interest to the aviation community, where carbon/carbon composite heatsinks are commonly used, is the aircraft response at deceleration onset. There are two performance measures defining brake system performance at braking onset: deceleration onset rate and system response time. The latter is strictly a function of the brake system hydraulics and is not affected by brake lining friction. The former performance measure is a function of both system hydraulics and brake lining friction. Previously to the work herein, carbon heatsink friction was thought to be unpredictable at braking onset. That being the case, a predictive capability for deceleration onset rate was not previously undertaken. This meant that assessment of this performance measure waited until aircraft taxi tests were performed.

The Boeing F/A-18 E/F Program Wing Team, Lean Organization and Phantom Works have partnered to develop a “state of the art” lean production system for the Outer Wing that represents an evolutionary change in aircraft design and assembly methodology. This project is focused on improving quality, cycle and cost performance through the implementation of lean principles, technology integration and process improvements. This paper will discuss the approach taken to reach the end state objectives and the technologies and processes being developed to support it. Items to be discussed include lean principles and practices, new tooling concepts, improved part assembly techniques, advanced drilling systems, process flow enhancements and part handling/part delivery systems.

Traditional thermal design criteria for avionics equipment are reviewed. Several studies have recently been conducted on the F-15 to assess accuracy of these design criteria. An overview of the study approach and results are presented. Specific topics investigated include: emergency cooling air provisions, cold start-up, hot start-up, normal and transient bay temperatures, and altitude design. The results indicate that many existing design criteria are overly conservative. The study findings suggest that reform of the existing thermal specification process is needed. Many of these reforms are applicable to the general aerospace industry and may result in significant acquisition cost savings as a result of the trend toward usage of commercial electronic parts. The reforms suggested include a new performance based thermal specification approach that increases emphasis on aircraft usage and frequency of occurrence. New transient design criteria are also recommended.

Aircraft manufacturing in the 21st century sees a future much different to that seen one and two decades before. Manufacturers of both military and commercial aircraft are challenged to become Lean, Agile and Flexible. As progress is slowly made toward introducing advanced assembly systems into production, the overall cost of automation is now more closely scrutinized. After spending tens of millions of dollars on large automated systems with deep foundations, many manufacturers find themselves locked into high cost manufacturing systems that have specific, inflexible configurations. This kind of scenario has caused a shift in the attitude of airframe assemblers, to go back to basics. Lean manufacturing is seen as a way to build aircraft with very low investment in equipment and tools. Today's advanced systems developers do understand the need for more affordable assembly systems.

A successful methodology was developed at Boeing Company to investigate hot-gas ingestion in vertical take-off and landing aircraft. It involves sub-scale model testing using specialized test facilities and test techniques. The baseline characteristics of hot-gas ingestion (HGI) and the performance of various HGI reduction techniques were qualitatively evaluated in the Boeing Hover Research Facility. Potential HGI reduction devices were then further tested at scaled pressures and temperatures in HGI facilities at NASA Lewis, Rolls Royce and British Aerospace. One of the successful HGI reduction devices was flight tested. This paper describes the application of Boeing HGI reduction methodology to three specific aircraft configurations.

The evolution of a manufacturing organization toward “Lean” manufacturing does not necessarily come cheaply or quickly. It is the experience at Boeing that technology and different visions can dramatically impact the evolutionary process-consuming great amounts of time and resources. The Boeing of Spokane case study, where aircraft floor panels are manufactured1, is but one of several case studies that suggests moving to “Lean” manufacturing is usually done in large steps, not small ones. These initial steps can be costly unless the systems (equipment and workforce) are flexible. Workforce flexibility is dependent on the attitude in the workforce as both touch and support labor move from their comfort zone to try new approaches and job descriptions. The workforce must be properly motivated to make the change. The equipment must also be flexible in adapting to new line layouts, product mixes, and process change or large cost penalties will be incurred.

A new process has been developed to cold work fastener holes on commercial aircraft flap tracks fabricated of 4340M steel. The process consists of pressing a high strength solid mandrel through a previously prepared hole in a defined manner. This process exhibits high tool life, low overall cost and eliminates the necessity for a final ream operation.

Flight testing of aircraft under natural icing conditions can be extremely tedious, time consuming, costly, and somewhat risky. However, such testing has been required to demonstrate the effectiveness of anti-icing systems and to certify new aircraft models. To reduce the need for extensive flight testing, Boeing has built a new icing tunnel that has the capability for developing ice shapes and evaluating anti-icing features on full scale sections of critical parts of the aircraft. The icing tunnel was made by modifying an existing 5 ft by 8 ft Boeing Wind Tunnel to add icing capabilities. This paper describes the design specifications, the tunnel capabilities, and the major equipment systems and presents the results of the tunnel calibration relative to the specified requirements.

Passengers and flight attendants often notice a haze of smoke under the overhead stowage bins in aircraft cabins when cigarette smoking is allowed. As normally operated, the ventilation system in Boeing 737/757 aircraft does not rapidly remove this smoke haze. Air ionization systems from three vendors were tested in a 10 foot long Boeing 737/757 cabin test section with a cruise condition ventilation rate and two cigarette smoking rates to assess their effectiveness in removing smoke haze from the local breathing areas of passengers and flight attendants. Smoke particulate densities were monitored at five breathing areas and at an exit grill in the test section. All of the ionization systems significantly increased the rate of smoke removal after smoking had stopped, increasing the removal rate by about 25%. None of the systems showed a statistically significant reduction of smoke levels at the individual monitoring points while cigarettes were being smoked.

A loosely coupled method for aeroelastic predictions of aircraft configurations is shown. This method couples an advanced structural analysis method with a CFD aerodynamics code in a modular fashion. This method can use almost any CFD code, so a validation of several such codes is shown to establish regions of validity for each code. Results from potential codes, an Euler code, and a Navier-Stokes code are shown in comparison with experiment. Viscous effects are included in most cases through a coupled boundary-layer solver or a turbulence model as appropriate.

This paper addresses the question of whether automation is being used in the proper applications in aircraft in order to maximize aircraft capabilities and make the most of human performance capacity. It is believed that the aircraft designers, while employing automation, have given due regard to the pilot's role as operator and manager of the aircraft. There does, however, seem to be valid concern for the human element in certain aspects of the air traffic control system.

The new 757/767 transports will be the first Boeing Commercial aircraft to commit advanced graphite composite material to initial production. Composite materials, mainly fiberglass in an epoxy matrix, have been used in Boeing military and commercial aircraft in ever increasing amounts for the past twenty (plus) years. Recently, the state-of-the-art of Advanced Composites (graphite and graphite/Kevlar hybrids in an epoxy matrix) progressed to the level that it could be committed to full-scale production. This production commitment resulted in a multi-year, multi-million dollar development program. This was to assure technical and production readiness, and product reliability to meet the stringent performance and safety standards of modern commercial transport.

The experimental procedure employed to define the natural modes of vibration of the 747 Shuttle Carrier Aircraft and Space Shuttle Orbiter mated configuration is described. A discussion of test results and comparison to structural analysis results is also included. Random transient signals were used as inputs to electromagnetic shakers to provide excitation to the mated vehicle test configuration. Acceleration signals were processed via the Fast Fourier Transform algorithm. Magnitude and phase transfer functions were formed and processed to produce modal frequencies, damping, and modal displacements.

Recent applications of numerical optimization to the design of advanced airfoils for transonic aircraft have shown that low-drag sections can be developed for a given design Mach number without an accompanying drag increase at lower Mach numbers. This is achieved by imposing a constraint on the drag coefficient at an off-design Mach number while the drag at the design Mach number is the objective function. Such a procedure doubles the computation time over that for single design-point problems, but the final result is worth the increased cost of computation. The ability to treat such multiple design-point problems by numerical optimization has been enhanced by the development of improved airfoil shape functions. Such functions permit a considerable increase in the range of profiles attainable during the optimization process.

High maintenance costs of the three 40,000 lb. thrust class aircraft engines manufactured by Pratt and Whitney, General Electric, and Rolls-Royce are discussed. Primary emphasis is on existing engine problems which contribute to high shop visit rate. Maintenance cost in terms of monetary value is not discussed. Concludes that increased emphasis on total life cycle durability is necessary by the engine manufacturers. Recommends higher level of priority be given durability in design and analysis, pre-production proof-of-design testing, and engine program management.

NASA, in cooperation with the FAA, is evaluating the two-segment approach as a routine procedure for reducing aircraft noise. The program calls for separate flight evaluations using a 727 and a DC-8, and an extrapolation of these results to determine the adaptability of the technique to the rest of the fleet. After a review of the total program, this paper presents (i) the profile and procedures developed and the noise reduction achievable, (ii) the vortex characteristics behind an aircraft on a two-segment path, and (iii) cost estimates for retrofitting aircraft with two-segment avionics.

Recent noise technology advancements have provided an increased understanding of true engine noise “floor” levels. This has led to changes in necessary engine cycle requirements for low-noise commercial airplanes. Updated prediction techniques for the core and jet noise sources are described, and lining technology improvements are reviewed. The need for further work in the core noise area is emphasized. The impact of these noise technology revisions on the best engine cycle for obtaining low noise is presented. It is concluded that engines with lower bypass ratios than previously anticipated may be acceptable.

This paper is an overview of the status of lift fan transport technology. Selected results of recently completed NASA in-house and contractual research investigations are included within the general areas of lift fan transport design: propulsion, acoustics, integrated propulsion/airframe/aircraft control systems, piloted moving-base simulation, and aircraft aerodynamics. On-going NASA lift fan transport research is briefly summarized, and a possible next step in the overall program is suggested.

This paper addresses the three questions: “Is V/STOL capability economically viable for business aircraft, and if so, how does the viability depend on the aircraft concept?”; “How is a V/STOL concept chosen to match a given mission, and what are some of the promising V/STOL concepts for future business aircraft?”; and “What unique operational requirements are likely to be imposed on users of future V/STOL business aircraft?” A cost-benefit analysis is presented which indicates that a VTOL business aircraft would be more viable economically than a contemporary turbine-powered business aircraft. The combinations of traveler's time value and trip distance for which each aircraft dominates is shown. A discussion is presented on the significance of disc loading as it relates to V/STOL concept application. Preliminary design configuration studies for three different business-aircraft-sized V/STOLs, using three concepts covering a range of disc loading, are presented as examples.

The joint development of an augmentor wing jet STOL research aircraft by NASA and the Canadian Government Department of Industry, Trade, and Commerce has progressed to the point that the design of the modifications to the de Havilland C-8A Buffalo are complete and the engines are being tested. The predicted performance shows that the airplane will be able to take off and land in less than 1500 ft. Simulation studies indicate that the handling qualities of the airplane, with stability augmentation, will be acceptable for STOL research missions.