High Fidelity MDO Process Development and Application to Fighter Strike Conceptual Design

Empirical sizing guidelines such as tail volume coefficients have long been used in the early aircraft design phases for sizing stabilizers, resulting in conservatively stable aircraft. While successful, this results in increased empty weight, reduced performance, and greater procurement and operational cost relative to an aircraft with optimally sized surfaces. Including flight dynamics in the conceptual design process allows the design to move away from empirical methods while implementing modern control techniques. A challenge of flight dynamics and control is the numerous design variables, which are changing fluidly throughout the conceptual design process, required to evaluate the system response to some disturbance. This research focuses on addressing that challenge not by implementing higher order tools, such as computational fluid dynamics, but instead by linking the lower order tools typically used within the conceptual design process so each discipline feeds into the other. In thisresearch, flight dynamics and control was incorporated into the conceptual design process along with the traditional disciplines of vehicle sizing, weight estimation, aerodynamics, and performance. For the controller, a linear quadratic regulator structure with constant gains has been specified to reduce the user input. Coupling all the disciplines in the conceptual design phase allows the aircraft designer to explore larger design spaces where stabilizers are sized according to dynamic response constraints rather than historical static margin and volume coefficient guidelines.

A case is made that introducing CAD-based geometry prematurely in the aircraft design process actually hinders multidisciplinary design. Consequently, a design process which allows a designer to quickly build and analyze aerospace configurations without CAD or computational meshing specialists is proposed. This allows higher fidelity analyses to be applied at conceptual design and decreases the turnaround time for trade studies and optimizations. The basic premise of conceptual geometry modeling is presented and discussed. Key features and capabilities which are essential for a successful geometry modeler are identified. Desktop Aeronautics' conceptual geometry modeler, RAGE, is described, with emphasis on recent progress and advances in the tool. A preliminary graphical-user-interface is presented along with an application programming interface. Extensibility of the RAGE modeler is discussed along with the importance of this feature. The applicability of RAGE to simple trade studies is demonstrated in an example problem. The precision of the RAGE modeler is also demonstrated on a complex aircraft design. Future plans for the geometry modeler are also discussed. I. Background In the conceptual phase of aircraft design, there is often a wide range of geometric configurations that the designer wishes to consider, analyze, and assess. A designer’s intuition and creativity are crucial to a successful conceptual design, yet are easily inhibited by the modeling and analysis process itself, particularly if high-fidelity analysis is warranted. If the time between inception and assessment of a candidate design is relatively long, a designer may be forced to limit the number of concepts considered. New data revealed in a design iteration may suggest or require significant changes to the geometry configuration. Since the majority of considered design configurations will eventually be discarded, an ideal conceptual design process should involve a highly efficient and easy to use geometry modeler. Significant changes should be allowed without tedious re-work of the geometry model. Exporting the model for analysis should require little effort and have the capability to be automated. Therefore, any modeling application used in this process should be flexible and not restrict the designer’s choice of user interface, analysis method, and design optimization environment. Most current design processes in the aerospace industry rely heavily on computer-aided-design (CAD) applications. As a general design tool, CAD is a powerful geometry modeler capable of precisely representing practically any shape. Unfortunately, this generality is realized at the cost of requiring specialized training to efficiently and effectively use the software. Also, a CAD model is often not easily modified, especially if significant re-work of the geometry is necessary. This can lead to the premature freeze of an aircraft design due to employing excessively high-fidelity geometry modeling too early in the design process. Parametric CAD modeling could address this issue, but creating a well-designed parametric CAD model is difficult. Not only does it require an extremely skilled operator, but also the designer must have some insight into what parameterization may ultimately be desired. Modifying a parametric CAD model is often more difficult than modifying a conventional CAD model. Significant changes, such as adding or removing cross-sections, may invalidate the parameterization in some cases. In most organizations, CAD modeling (whether it be parametric or conventional) is often assigned to a dedicated CAD specialist. Since the conceptual designer is usually not a CAD specialist, the latter must communicate his design intent to the former, often using sketches, dimensions, and word of mouth. When the CAD specialist interprets the sketches, any part or detail not precisely defined usually requires judgment and artistic license. This interpretation may result in loss of design intent and indeterminate iteration between the CAD specialist and designer to obtain a satisfactory result. Because this process is iterative, CAD operators often must recreate similar geometry

The major concern in the architecture, engineering, and construction (AEC) industry is time, cost, and quality. The design for industrial building project usually complex, particularly in a field of mechanical and piping process due to the large involvement of project stakeholders. The case company, which is the specialist supplier of industrial piping solution in Thailand, reported the issue of redesigns regarding to their poor project management of conceptual design process in construction project that effect to their work performance and customer satisfaction. Thus, the purpose of this study was to improve the process of conceptual design using project management concept to reduce the number of redesign in the conceptual design phase for storm drainage design projects. The new conceptual design process was introduced in 4 stages-Initialization, Identification, Translation, and Specification. These stages were clearly defined their input, process (with project management plans, tools and techniques such as checklist, tree diagram, 3D model system and expert judgment), and output.
 
 This was validated with 30 pilot projects of storm drainage design in factories and warehouses. The results revealed that, the total number of redesign was reduced from 102 to 24 under the satisfied of company?s KPI. In addition, the total cost of redesign was decreased form THB 1,326,000 to THB 31,200. Furthermore, the total design time from the start to finish the specification output was reduced from 327 days to 212 days. Therefore, the proposed solution was proved to be practical and fully implemented by the company.

Genetics-based design is an effective approach to develop novel products for conceptual design. It could reduce innovation blindness by providing logically structured procedure. However, the major challenge of genetics-based engineering method is that how to identify what information is genetic information and how to use it in a conceptual design process. To solve this problem, this article proposes a conceptual design method driven by product genes. First, a functional expansion model is established based on analyzing the conceptual design process. Second, to respectively compare the functions and structure schemes in the model to biological traits and proteins, a product gene definition composed of behaviors and attributes is put forward. Then, a modeling and coding method of product genes is given analogous to that of biological genes. Third, operation technologies of product genes are analyzed, including breakdown, crossover, recombination, transcription, and translation. Based on this, a conceptual design method driven by product genes is advanced. Finally, an example shows that this method is able to extract key information of products and gives a method of how to use the information in a conceptual design process. Moreover, structure schemes obtained through this method are of high feasibility and have more possibilities of innovation.

The objective of this research project is the development of a second generation in-duct sorbent injection technology as a cost-effective compliance option for the 1990 Clean Air Act Amendments. Research focused on the Advanced Coolside Process, which has shown the potential of exceeding the performance targets of 90% SO{sub 2} removal and 60% sorbent utilization. In Task 5, Conceptual Process Design and Economic Evaluation, the economics of the CONSOL Advanced Coolside Process as a Clean Air Act compliance option were evaluated. A conceptual process design for full-scale, coal-fired applications is described. Advanced Coolside is compared to conventional Limestone Forced Oxidation (LSFO) wet FGD technology. The process economics for coal sulfur levels ranging from 1.0% to 3.5% (as-received) and plant sizes ranging from 160 to 512 gross MW were investigated, In addition, the economics of on-site versus off-site lime hydration and the cost sensitivity to delivered pebble lime and hydrate prices are investigated, Advanced in-duct sorbent injection enjoys a capital and levelized cost advantage relative to LSFO in all cases examined in this study. As a result of this study and others made during this contract, the following conclusions can be made: (1) The capital cost of Advanced Coolside is 55% to 60% less than that of LSFO and varies slightly depending on coal sulfur content and plant size. (2) The total levelized SO{sub 2} control cost advantage relative to LSFO varies from 15% to 35% over the range of coal sulfur contents and plant sizes evaluated. This cost advantage is sensitive to sorbent transportation charges. As a result, the economics are site-specific. (3) The experimental optimizations based on interim economic analyses were the key to capital and levelized cost reductions.

An expert system for the conceptual design of bridges

In current day’s Unmanned Aerial Vehicle (UAV) are widely used in every field, almost from military till the commercial purpose. Usage of UAV has decreased the burden on the human, where the manpower and risks during critical conditions (war fields) are reduced. Therefore the demand for the development of the unmanned aerial Vehicle is high. Interpreting the conceptual design data of UAV is difficult because of lack of availability of their data sheets. This paper is addressed to develop a conceptual design process of high-performance UAV, which carries a maximum payload of about 300kg and can travel for the maximum range 900km/hrs. For about 50 hours of maximum endurance. Where these three parameters are considered as the main requirements. By drawing constraint diagram, feasible design space for the aircraft was frozen; using which initial sizing of the wing, wing airfoil selection, and a suitable power-plant selection was done. Fuselage design was carried out looking at the available literature on the existing aircrafts. Propeller design was done to match the thrust requirements obtained from the constraint diagram. Empennage design was done to achieve the desired static margin of the aircraft. This process completes the conceptual design of UAV, where designed aircraft meets the requirement. The outcome of this paper enhances the understanding of the conceptual design process for the academicians as well as the researchers.

Design cognition research aims to investigate the cognitive mechanisms and thought processes of human designers. In previous research, the cognitive activity of experienced and inexperienced designers has been compared in order to identify design strategies leading to design creativity. However, it is still unknown whether the design strategies applied are effective and whether the design processes are efficiently improved. In this paper, cognitive efficiency, describing how designers optimize mental resources to achieve creativity in conceptual design processes, was directly measured by the mental effort of designers and the creativity level of design outcomes. The results showed that the experienced designers generated more design concepts with higher quality and variety than did the inexperienced designers. The cognitive efficiency measures indicated that design expertise contributed to improving cognitive efficiency scores of quality. In addition, the systematic design method used by some designers was found to be related to high cognitive efficiency. It can be seen that the evaluation of cognitive efficiency has practical applications for designer training, design methodology evaluation, and design process improvement.

After the analysis of design process of mechanical products, the paper pointed out that the structure design is the key of the connection between conceptual design and detail design process. The paper introduced a method that based on conceptual information knowledge unit for structure design of products. It defined knowledge unit and structure unit, and encapsulation of conceptual information into knowledge (structure) unit to realize the information interconnection and drive mechanism from conceptual design to structure design thus making knowledge structure unit become the main carrier representing product design knowledge; expressed design rules and design knowledge based on knowledge units to establish knowledge library of product design; and then expressed different mechanic structure through combination and variation of knowledge (structure) units during the design process to realize product design; finally, analyzed the structure features of multi-cavity injection mold systems (from 1-cavity mold to multi-cavity mold), and expressed the mold structure by knowledge units, based on which the method of multi-cavity plastic injection mold system design was realized.

Computer-aided conceptual design (CACD) aims to increase efficiency and quality of design work but with little essential progress due to the gap between abstract concept and detailed structure. In order to tackle the problem concerned with conceptual design process and automation, this paper introduces the concept of functional surface as the information carrier to link together product function and structure and describes a product genetic model to represent and organize product information. Functional surface is used to formalize the product gene, a varied-length coding scheme for functional surface and product gene is proposed, and the design process model for conceptual design is established based on product gene. Finally, a prototype system for CACD is introduced to demonstrate how a product can be designed based on the proposed model.

Conceptual design traditionally is accomplished with the lowest fidelity tools available to the design engineer augmented with high fidelity aerodynamics. However decisions made during this relatively short period of time have a very large impact on the life-cycle cost and performance of an aircraft. Historically a configuration and associated outer mold line for a design is selected without considering all the relevant technologies, multi-disciplinary interactions or all the single disciplines that will have an impact on the vehicle. Most methods are focused primarily on the aerodynamics with very low fidelity empirical methods applied to the other disciplines. This paper focuses on a method of bringing multiphysics based analysis forward, into the conceptual design process. The paper will discuss improving the design process to keep more than a single configuration in consideration until they have been evaluated with higher fidelity multi-disciplinary tools. Finally the paper will introduce a new rapid model generation tool being developed within the Air Force Research Lab. The rapid model generator generates aeroelastic models for MSC Nastran, ASTROS and ZAERO. It supports drag prediction from AWAVE for supersonic wave drag and other tools to estimate viscous drag at zero lift conditions. Additionally aerodynamic models for rigid vortex lattice methods are generated to estimate drag polars for use in performance calculations.

<div class="section abstract"><div class="htmlview paragraph">Current transport aircraft are mature systems, thus require increased fidelity at the beginning of the design process to allow further optimization. Furthermore, a desire exists to explore unconventional aircraft configurations at the conceptual level. This has motivated the development of a tool which effectively manages the trade-off between high-fidelity levels, flexibility and short turn-around times. This paper presents a CATIA V5-based parametric aircraft geometry modeler developed by Bombardier Aerospace. The aim of the tool is to provide consistent high-fidelity geometric data early in the conceptual aircraft design process.</div><div class="htmlview paragraph">The intended near-term use of the modeler is two-fold: during the early design phase, the modeler computes geometric data such as areas, volumes, ESDU aircraft parameters, etc. In the competitive analysis domain, the tool provides a high-quality three-dimensional model with manageable effort. In both cases, the engineer is presented with a fully parametric three-dimensional CATIA V5 aircraft model. In the medium-term, use by expert departments is envisioned. </div><div class="htmlview paragraph">Moreover, the geometrical data extracted from CATALIST can be saved into a standard database and fed to various analysis codes to compute aircraft performance characteristics. As aircraft models are in native CATIA V5 format, this fits seamlessly into the established design process at Bombardier Aerospace. Additionally, this approach allows critical analyses to be performed earlier in the conceptual design phase.</div><div class="htmlview paragraph">Aircraft exterior and interior modules are in use today along with systems modules and a basic structural representation. An overview of the key features of the tool is presented along with sample applications. Tool usability and modeling quality have been extensively validated with selected regional aircraft and business jets from Bombardier.</div></div>

Additive Manufacturing (AM) brought new design freedom and possibilities that enable design and manufacturing of products with new forms and functionalities. To utilise these possibilities a new design approach emerged, Design for Additive Manufacturing (DfAM), that contains methods and tools for supporting AM oriented design process. Designers working with AM are aware of the need to apply DfAM and AM possibilities in conceptual design phase where they have the most significant influence on product architecture and form but are facing a lack of suitable DfAM approaches for early design phases. Therefore, the presented research is investigating possibilities of storing and representing AM knowledge in the form of design principles to be used in the conceptual design phase. The paper proposes conceiving of Design Principles for Additive Manufacturing repository where formalised AM knowledge is stored in the form of design principles and structured based on function criteria. In the paper, various elements of design principle representation are discussed, as well as their role in the conceptual design process.

Advanced technologies such as Active Flow Control (AFC) offer the potential to revolutionize next generation aircraft design through enhancing aircraft maneuver, control, and operation. DARPA’s CRANE (Control of Revolutionary Aircraft with Novel Effectors) program seeks to incorporate AFC into an aircraft design, then build and fly an X-Plane to demonstrate the potential capabilities and benefits of AFC technology. As a performer in the Phase and Phase 1 programs, Lockheed Martin has made significant progress on the development of a full-scale, tailless aircraft with an integrated AFC system to enable unique maneuvers without the use of conventional control surfaces. The Lockheed Martin-led team developed an approach that consisted of four key activities. 1. Design Library. Developing a multi-variate aerodynamic database (design library) for Active Flow Control. This was an offline process using CFD tools and significant HPC computing resources to model the complex aerodynamics and boundary layer affects associated with AFC. Response Surface Models were developed to integrate the aerodynamic effects of AFC into the Conceptual Design Process. 2. Conceptual Design Methods. Developing new methods and tools that would properly account for the effects of AFC. This included updating Stability and Control models to determine control power required and control power available, updating flight control model simulations for implementation of AFC, updated MDAO models to incorporate the changes to aero, propulsion, mass properties, and updating Operations Analysis models to model new maneuvers and behaviors achievable with AFC. These new methods were used in conducting trade studies for the design of the AFC system, the propulsion system, and the air vehicle. 3. RPV Verification. Performing test activities that help verify and calibrate our analytical methods, as well as reducing key risks. Multiple wind tunnel tests were conducted to validate the numerical simulations and gather data to capture the forces and moments generated by the various fluidic effectors on the vehicle. A subscale, dynamically scaled RPV (Remotely Piloted Vehicle) with integrated AFC was built and flown to gather additional data on aspects of interest such as flight controls and control authority, while serving as risk reduction for the larger scale X-Plane. 4. X-Plane Design. Complete the design of an AFC-enabled X-Plane. The X-Plane will serve as validation of our methods as well as demonstrate the potential for AFC to enable new and compelling mission capabilities. The work in Phase 1 matures the X-Plane design in preparation for a Preliminary Design Review. This presentation will provide an overview of the Lockheed Martin team’s progress, while highlighting challenges, solutions developed, and lessons learned under the DARPA CRANE program.

In order to reduce the risks and uncertainties in conceptual design of submarine rescue vehicle (SRV), the paper proposed a risk-based conceptual design method, which consisted of three focus areas: problem setup, risk assessment, risk mitigation and decision support. Conventional risk assessment tools (e.g. probability risk assessment) were not suited for initial design because of lack of data, and a safety analysis model using fuzzy-logic approach employing fuzzy IF-THEN rules was introduced to carry out risk analysis in conceptual design. Subsequently, it was investigated that the main risky factors which influenced system risk in initial design were technology level of SRV, safety of SRV, task complexity, investment and repayment. And then a risk analysis model for submarine rescue vehicle was introduced. Lastly a case was studied to demonstrate the application of the model, and the results showed that it was an effective way to reduce the risks and uncertainties in conceptual design process.