ACEE composite structures technology

Toppics addressed include: advanced composites on Boeing commercial aircraft; composite wing durability; damage tolerance technology development; heavily loaded wing panel design; and pressure containment and damage tolerance in fuselages

A multi-perspective dynamic feature concept in adaptive NC machining of complex freeform surfaces

This paper presents a new concept of feature for freeform surface machining that defines the changes in feature status during real manufacturing situations which have not been sufficiently addressed by current international standards and previous research in feature technology. These changes are multi-perspective, including (i) changes in depth-of-cut: the geometry of a feature in the depth-of-cut direction changes during different machining operations such as roughing, semi-finishing and finishing; (ii) changes across the surface: a surface may be divided into different machining regions (effectively sub-features) for the selection of appropriate manufacturing methods for each region such as different cutting tools, parameters, set-ups or machine tools; and (iii) changes in resources or manufacturing capabilities may require the re-planning of depth-of-cuts, division of machining regions and manufacturing operations (machines, tools, set-ups and parameters). Adding the above dynamic information to the part information models in current CAD systems (which only represent the final state of parts) would significantly improve the accuracy, efficiency and timeliness of manufacturing planning and optimisation, especially for the integrated NC machining planning for complex freeform surfaces. A case study in an aircraft manufacturing company will be included in this paper

Optimization of compliant adaptive structures in the design of a morphing droop nose

A design procedure for the synthesis of active camber morphing wing devices is proposed. A topology optimization initially defines the internal structure that is further enhanced by structural size and shape optimizations, and these optimizations are based on the distributed compliance concept. The size optimization enables the adaption of the topology solution to other materials and geometries while refining the topology solution to improve the shape quality of the skin deformation. Then, the structural shape optimization enables the reduction of the stress peaks inside the compliant structure and the finalization of the details to obtain a solution that is closer to the manufacturing process stage. The proposed methodology is used in the design of an adaptive droop nose to be installed on a reference regional aircraft, and two different design applications are considered. The first application is the validation of the procedure at the full scale level using a superelastic material for the internal structure. The second application is the design of a corresponding 3D-printed prototype, in which both geometry and material changes are considered, for experimental validation. The results show satisfactory shape quality and the achievement of structural feasibility. The experimental functional test of the scaled prototype demonstrates the effectiveness of the adopted morphing solution

Application of advanced technologies to small, short-haul aircraft

The results of a preliminary design study which investigates the use of selected advanced technologies to achieve low cost design for small (50-passenger), short haul (50 to 1000 mile) transports are reported. The largest single item in the cost of manufacturing an airplane of this type is labor. A careful examination of advanced technology to airframe structure was performed since one of the most labor-intensive parts of the airplane is structures. Also, preliminary investigation of advanced aerodynamics flight controls, ride control and gust load alleviation systems, aircraft systems and turbo-prop propulsion systems was performed. The most beneficial advanced technology examined was bonded aluminum primary structure. The use of this structure in large wing panels and body sections resulted in a greatly reduced number of parts and fasteners and therefore, labor hours. The resultant cost of assembled airplane structure was reduced by 40% and the total airplane manufacturing cost by 16% - a major cost reduction. With further development, test verification and optimization appreciable weight saving is also achievable. Other advanced technology items which showed significant gains are as follows: (1) advanced turboprop-reduced block fuel by 15.30% depending on range; (2) configuration revisions (vee-tail)-empennage cost reduction of 25%; (3) leading-edge flap addition-weight reduction of 2500 pounds

Aircraft wing structure benchmark: cantilever vs. braced wing configurations

Dissertação de mestrado integrado em Mechanical EngineeringThis thesis presents a comprehensive analysis of aircraft wing structures, specifically comparing cantilever and braced wing configurations across a range of aspect ratios. The study employs Hypermesh, a powerful finite element analysis tool, which is a standard software in the aeronautical industry, to investigate the structural performance of these two wing designs. The objective is to provide recommendations for the use of wing braces in different aspect ratio scenarios, using the Cessna 408 Skycourier as a reference aircraft model for the finite element model (FEM). This work encompasses five different aspect ratios, ranging from 9.8 to 13.8, with incremental steps of one unit. Two critical analyses, SOL101 static analysis and SOL105 buckling analysis, are conducted to assess the structural integrity and stability of both cantilever and braced wing configurations. Through these analyses, the study examines factors such as stress distribution, maximum stress, and critical buckling loads. Also, it includes a connection angle study, to define the angle range for a sized brace. By comparing the performance of cantilevered and braced wing configurations with different aspect ratios, it was shown that the braced wing configuration is more advantageous for the class of aircraft CS 23, particularly in terms of structural weight. This represents a weight saving of around 35%, corroborating previous studies, which translate into greater range, greater payload capacity and lower operating costs.Esta tese apresenta uma análise exaustiva das estruturas das asas de aeronaves, comparando especificamente as configurações de asas em cantilever e com tirantes numa série de razão de aspecto de asa. O estudo utiliza o Hypermesh, uma poderosa ferramenta de análise de elementos finitos, que é um software padrão na indústria aeronáutica, para investigar o desempenho estrutural destas duas configurações de asa. O objetivo é fornecer recomendações para a utilização de tirantes de asa em diferentes cenários de razão de aspeto, utilizando o Cessna 408 Skycourier como modelo de aeronave de referência para o modelo de elementos finitos (FEM). Este trabalho abrange cinco razões de aspeto diferentes, variando de 9,8 a 13,8, com passos incrementais de uma unidade. São efectuadas duas análises críticas, a análise estática SOL101 e a análise de encurvadura SOL105, para avaliar a integridade estrutural e a estabilidade das configurações de asa em cantilever e com tirantes. Através destas análises, o estudo examina factores como a distribuição de tensões, a tensão máxima e as cargas de encurvadura críticas. Inclui também um estudo do ângulo de ligação, para definir a gama de ângulos para um tirante dimensionado. Ao comparar o desempenho das asas em cantilever e com tirantes com diferentes rácios de aspeto, foi demonstrado que a configuração com tirantes é mais vantajosa para a categoria de aeronaves da classe CS-23, designadamente em termos de peso estrutural. Isto representa uma poupança de peso na ordem dos 35%, corroborando os estudos anteriormente realizados, que se traduzem num maior alcance, maior capacidade de carga útil e menores custos operacionais

Space shuttle: Structural integrity and assessment study

A study program was conducted to determine the nondestructive evaluation (NDE) requirements and to develop a preliminary nondestructive evaluation manual for the entire space shuttle vehicle. The rationale and guidelines for structural analysis and NDE requirements development are discussed. Recommendations for development of NDE technology for the orbiter thermal protection system and certain structural components are included. Recommendations to accomplish additional goals toward space shuttle inspection are presented

Technology for large space systems: A special bibliography with indexes (supplement 03)

A bibliography containing 217 abstracts addressing the technology for large space systems is presented. State of the art and advanced concepts concerning interactive analysis and design, structural concepts, control systems, electronics, advanced materials, assembly concepts, propulsion, solar power satellite systems, and flight experiments are represented

An Analytical Study for Subsonic Oblique Wing Transport Concept

The oblique wing concept has been investigated for subsonic transport application for a cruise Mach number of 0.95. Three different mission applications were considered and the concept analyzed against the selected mission requirements. Configuration studies determined the best area of applicability to be a commercial passenger transport mission. The critical parameter for the oblique wing concept was found to be aspect ratio which was limited to a value of 6.0 due to aeroelastic divergence. Comparison of the concept final configuration was made with fixed winged configurations designed to cruise at Mach 0.85 and 0.95. The crossover Mach number for the oblique wing concept was found to be Mach 0.91 for takeoff gross weight and direct operating cost. Benefits include reduced takeoff distance, installed thrust and mission block fuel and improved community noise characteristics. The variable geometry feature enables the final configuration to increase range by 10% at Mach 0.712 and to increase endurance by as much as 44%

Aerodynamics, Stability and Control of the 1903 Wright Flyer

The Los Angeles Chapter of the American Institute of Aero and Astronautics is building two replicas of the 1903 Wright Flyer airplane; one to wind-tunnel test and display, and a modified one to fly. As part of this project the aerodynamic characteristics of the Flyer are being analyzed by modern wind-tunnel and analytical techniques. Tnis paper describes the Wright Flyer Project, and compares key results from small-scale wind-tunnel tests and from vortex-lattice computations for this multi-biplane canard configuration. Analyses of the stability and control properties are summarized and their implications for closed-loop control by a pilot are derived using quasilinear pilot-vehicle analysis and illustrated by simulation time histories. It is concluded that, although the Wrights were very knowledgeable and ingenious with respect to aircraft controls and their interactions (e.g., the good effects of their wing-warp-to-rudder linkage are validated), they were largely ignorant of dynamic stability considerations. The paper shows that the 1903 Flyer was readily controllable about all axes but was intrinsically unstable in pitch and roll, and it could barely be stabilized by a skilled pilot