Search Results

During the NASA/FAA Tailplane Icing Program, pilot evaluations of aircraft flying qualities were conducted with various ice shapes attached to the horizontal tailplane of the NASA Twin Otter Icing Research Aircraft. Initially, only NASA pilots conducted these evaluations, assessing the differences in longitudinal flight characteristics between the baseline or clean aircraft, and the aircraft configured with an Ice Contaminated Tailplane (ICT). Longitudinal tests included Constant Airspeed Flap Transitions, Constant Airspeed Thrust Transitions, zero-G Pushovers, Repeat Elevator Doublets, and, Simulated Approach and Go-Around tasks. Later in the program, guest pilots from government and industry were invited to fly the NASAT win Otter configured with a single full-span artificial ice shape attached to the leading edge of the horizontal tailplane.

The catastrophic decline of general aviation in the early1980’s – exemplified by the rapid fall in sales of single engine piston powered models – is old news. But as the industry, emboldened by legislative relief in product liability, now embarks on revitalization it is worth revisiting its history to see if there are any lessons for today. To an economist that history (starting post WWII) would include the impact of the evolving national economy on the industry and the contribution of “products” competing for the composite intercity travel and leisure markets in terms of price and changing tastes. Economists prefer statistical evidence to draw conclusions, and that has been gathered for addressing the specific competition with the airline industry as well as the market ceiling for general aviation airplanes. Quantitative, but non-statistical, evaluation of alternative ways of “flying” for recreation was also done. The results are not encouraging.

This paper describes the design and development of the Beech AT-10 multi-engine pilot transitional trainer. It also covers the use of the AT-10 as a research aircraft.

This paper provides a retrospective of the aerodynamics of the Bell P-39 Airacobra and the Bell P-63 Kingcobra. Design details and information obtained from several drag reduction investigations conducted on these aircraft are presented. Additionally, results from a modern Computational Fluid Dynamics analysis of these aircraft are shown.

A number of considerations must be addressed to properly install a propeller on an aircraft. These considerations consist of a number of technical and regulatory requirements. Propeller installations vary in complexity depending on the number and type of engines and propeller-related systems involved. Addressing the technical and regulatory requirements with prior FAA agreement will maximize the efficiency of the propeller installation development and approval process.

Improved safety standards are becoming a focus of the aerospace industry. In particular, standards for occupant protection have been changed to include dynamic seat testing and occupant injury assessment. Methods to model these situations are evolving. A method of modeling an occupant on a crew seat during a sled test is presented. This method combines a rigid body occupant model with a finite element model of the crew seat structure. Validation to sled test results obtained with the model is also presented. Modeling dynamic events with MADYMO software has been proven to be efficient and accurate in many aerospace and automotive applications. Using this tool, a model was developed to investigate how modeling can be used efficiently to provide guidance in crashworthy design. Both finite element methods (FEM) and multibody techniques were used to create a detailed model of a typical aircraft crew seat.

Results of a case study in which an unusual liner wear pattern is seen to form within the cylinders of a large marine diesel engine are presented. Analysis of the wear patterns and the wear surfaces are also presented which reveal that the maximum wear corresponds to regions on the liner where “varnish” or “lacquer” films appear to build up from decomposition products of the fuel and lubricants employed. Possible reasons for such wear and film formation are discussed, and compared with frictional and thermal analyses of the ring-liner contacts under operating conditions, with and without the presence of lacquer films. Preliminary results suggest that such films can act as insulation layers to frictionally generated heat between rings and liner, and if allowed to become thick enough can lead to scuffing.

In spite of being a popular topic in technical publications, scuffing between a piston ring face and the cylinder liner is an extremely unpredictable and hard-to-reproduce phenomenon that significantly decreases engine performance. The scuffing phenomenon described as the transfer of cylinder liner particles to piston ring surfaces due to inadequate lubrication and high temperature at top dead center could significantly decrease engine performance. The mechanism of scuffing origin and subsequent catastrophic seizure usually is evaluated by coefficient of friction measurements. The purpose of this paper is (1) to examine the usefulness of acoustic emission RMS measurements generated during testing that results from the friction between piston ring and cylinder liner segments and (2) to establish the relationship between such signals and different levels of the scuffing phenomenon.

The goals of this NASA Phase II SBIR program were to develop design methodology to improve occupant survivability in small composite airplanes. Current technology small airplanes absorb crash energy primarily in the cabin structure. The current study tried to increase strength of the occupant compartment and design energy absorbing structure outside the passenger compartment. Dynamics of the crash event were analyzed using a PC version of DYNA3D. Four full scale tests in two crash scenarios were conducted at the NASA Impact Dynamics Test Facility with test parameters set to allow direct comparison with prior NASA/FAA tests. Results indicate that occupant survivability can be improved with moderate weight penalty.

The effective implementation of a lean supply chain, focusing on the key issues that ensure success. These include the ‘softer’ issues of involving logistics thinking in pre-production activities that have now become as important as the traditional ‘hard’ issues surrounding product delivery.

Engine design and tribology engineers are constantly challenged to develop advanced products with reduced weight, reduced friction, longer life, and higher engine operating temperatures. The resulting engine systems must also meet more demanding emissions and fuel economy targets. Advanced energy-conserving lubricants and surface coatings are concurrently evolving to meet the needs of new engine materials. Because of the enormous cost and time associated with engine testing, much interest is being focused on the development of representative and repeatable bench tests for evaluation of engine materials and lubricants. The authors have developed a bench test employing reciprocating motion for evaluating friction and energy-conserving characteristics of lubricants.

This paper presents an overview of techniques for measuring friction using bench tests and fired engines. The test methods discussed have been developed to provide efficient, yet realistic, assessments of new component designs, materials, and lubricants for in-cylinder and overall engine applications. A Cameron-Plint Friction and Wear Tester was modified to permit ring-in-piston-groove movement by the test specimen, and used to evaluate a number of cylinder bore coatings for friction and wear performance. In a second study, it was used to evaluate the energy conserving characteristics of several engine lubricant formulations. Results were consistent with engine and vehicle testing, and were correlated with measured fuel economy performance. The Instantaneous IMEP Method for measuring in-cylinder frictional forces was extended to higher engine speeds and to modern, low-friction engine designs.

Members of supply chains face many conflicts between the efficient operation of the individual unit and the demands of membership in the supply chain. What is good for the Link isn't always good for the Chain. This paper addresses the conflicts and suggests sharing both risks and profits as a breakthrough solution that integrates tactics (the method of operations of the link) with strategy (the method of operations of the chain). Additional elements necessary to achieve the success are also discussed.

Best Practices in the Design and Deployment of Light Reconfigurable Assembly Systems Raul Fernandez Automation & Robotics Research Institute Romano Patrick Universidad Panamericana ABSTRACT The development of the Standard Assembly Cell (SAC) stands as one of the significant recent efforts to bring cost-justified automation in the area of light and medium electromechanical assembly to the defense aerospace industry. Supported both by a body of academic and industrial research and by the availability of infrastructure hardware off-the-shelf, the SAC is a commercial reality already under adoption within missile manufacturing. Drawing on the experience developing a prototype SAC for the automated assembly of inertial navigation components, sponsored by DARPA’s Affordable Multi- Missile Manufacturing program, this paper presents a compilation of selected physical and conceptual strategies - best practices - aimed at facilitating the continued deployment of this technology.

The C-17 program began its journey implementing supplier lean initiatives with the support of the United States Air Force (USAF) Systems Program Office (SPO). This paper includes the process the C-17 Supplier Lean Implementation Team uses to implement lean principles throughout the supply chain. The flow of a supplier lean event is explained including the education, value stream mapping, deployment strategy and execution of the plan. Also shared are integration activities with Lean Manufacturing and Lean Engineering.

Logistics, information exchange, and people all influence the capability and contribution to profits of the supply chain. Understanding how to analyze the current state, and set a strategy to achieve the desired end state is critical to success in the market place. This paper will focus primarily on the acquisition of components for a manufacturing/assembly operation. However, the principles and processes described can be applied to other segments of the chain, such as from the manufacturer to the customer, or to other components of manufacturing such as maintenance, repair and operating (MRO) supplies.

The increasing drive for productivity improvements and consistent part dimensionality in aerospace structures has lead to the advent of machined monolithic parts. High speed machining technology employed affords the manufacture of thin-walled parts from single billets of material, resulting in the removal of approximately 85% of the initial workpiece material. With thin-walled monolithic parts come the increased propensity for workpiece distortion and few arresting mechanisms for crack propagation, largely due to potentially unfavorable residual stress states. These imposed states of stress can be a result of the machining conditions used (e.g., feeds, speeds and cutter geometry). A general method is presented to model the residual stress state induced by metal cutting operations which takes into account workpiece thermo-mechanical properties, cutter geometry and process parameters. In this paper the model is specifically applied to Al7050.

As the performance and capabilities of the next generations of Military Aircraft structures are developed to higher levels, the manufacturing processes required to produce the airframe components are faced with increasing challenges such as increased component complexity and difficult raw materials for machining. The machining costs on materials such as Titanium have traditionally demanded high cutting tool consumable costs and slow machining cycle times. Similarly, the high wear of the cutting tools restricts the cutting process capabilities and as such produces a high requirement for manual finishing operations. This paper highlights the business drivers and the route that BAE SYSTEMS took in developing a consistent and reliable machining process for Titanium. Through focussing upon the aspects that have the greatest impact upon process costs, the development programme has delivered savings in excess of 60% in terms of both consumable costs and machining cycle time reductions.

The design tool developed addresses the need for timely and interactive manufacturing cost estimation early in product and process design. The particular context treated is finish turning of titanium. A collection of simple physical models of the most relevant phenomena are combined in a computer program. Model simplicity enables rapid delivery of results in the form of cutter temperature, force, and wear predictions. Knowledge of the specific nature of titanium machining is included. Cutter wear predictions agree well with experimental data. Process conditions and cutter geometry that result in minimum direct cost can be provided on time scales that are a fraction of the time to actually machine the part. This design tool is most appropriate for cost estimation of jobs in which cutters and/or machining time are a significant part of manufacturing cost.

The paper has two main goals. Firstly, it emphasizes the importance of including a legacy CAD data conversion system into a collaborative virtual prototyping (CVP) environment. 2D legacy data is of great intellectual value to the designer as reference data for designing new parts. Therefore, a legacy conversion system will help the user model parts more efficiently than by starting from scratch. This paper will then discuss a feature extraction system (FES) as a potential solution. This FES has the ability to automatically convert 2D legacy data into a variety of part formats and representations in a feature-based form, where the feature-based model representation provides more essential semantic data to designers and analysis. Secondly, this paper will describe how this feature extraction system can be inserted and interfaced into a CVP environment. There are several aspects to this task. Firstly, identifying a suitable architecture to use as the basic CVP infrastructure.