SAWE Technical Papers

@inproceedings{3246,

title = {3246. Predicted Production Costs for Advanced Aerospace Vehicles},

author = {Han P. Bao},

url = {https://www.sawe.org/product/paper-3246},

year  = {2002},

date = {2002-05-01},

booktitle = {61st Annual Conference, Virginia Beach, Virginia, May 18-22},

pages = {13},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virginia Beach, Virginia},

abstract = {For early design concepts, the conventional approach to cost would be some kind of parametric weight-based cost model. There is now ample evidence that this approach can be misleading and inaccurate. By the nature of its development, a parametric cost model requires historical data and is valid only if the new design is analogous to those based upon which the model was derived. Advanced aerospace vehicles have no historical production data and are nowhere near the vehicles of the past. Using an existing weight-based cost model would only lead to errors and distortions of the true production cost. 

This paper outlines the development of a process-based cost model in which the physical elements of the vehicle are costed according to a first-order dynamics model. This theoretical cost model, first advocated by early work at MIT, has been expanded to cover the basic structures of an advanced aerospace vehicle. Elemental costs based on the geometry of the design can be summed up to provide an overall estimation of the total production cost for a design configuration. This capability to directly link any design configuration to realistic cost estimation is a key requirement for high payoff MDO problems. 

Another important consideration in this paper is the handling of part or product complexity. Here the concept of cost modulus is introduced to take into account variability due to different materials, sizes, shapes, precision of fabrication and equipment requirements. A case study based on the preliminary analysis of the shape of a vehicle is presented to illustrate the approach for estimating its production cost. It is shown that changing the baseline ratio between pressurized area and non-pressurized area by as little as .5% would incur a cost variance of roughly 5% in cost (no linear relationship is implied) while using a weight-based cost model would result in no cost change because the overall weight of the vehicle remains practically the same. Ultimately the most important implication of the development of the proposed process-based cost model is that different design configurations can now be quickly related to their cost estimates in a seamless calculation process easily implemented on any spreadsheet tool.},

keywords = {11. Weight Engineering - Aircraft Estimation},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3113,

title = {3113. Composite Ejector Door Design Concept Evaluation for the HSCT Engine Nozzle},

author = {Russell and Foreman and Pauletti and Sauer and Courtney},

url = {https://www.sawe.org/product/paper-3113},

year  = {2001},

date = {2001-05-01},

booktitle = {60th Annual Conference, Arlington, Texas, May 19-23},

pages = {12},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Arlington, Texas},

abstract = {Weight savings requirements for the High Speed Civil Transport (HSCT) engine nozzle have motivated development of polymer matrix composite (PMC) and ceramic matrix composite (CMC) structural concepts for the nozzle secondary air ejector door. Initial trade studies of these concepts resulted in synthesis of a PMC sandwich door concept with CMC thermal protection system (TPS) as a promising candidate for further development. Thermal and structural analyses of this concept have been performed to permit a weight comparison with a baseline metallic door concept. A manufacturing plan has been developed to highlight producibility issues and support parametric cost estimating efforts. The final results show that the composite door concept has a modest weight advantage and a distinct cost disadvantage relative to the metallic concept. Risk mitigation and design recommendations have been developed to make the composite concept more attractive for future HSCT engine nozzle development efforts.},

keywords = {27. Weight Reduction - Materials},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3024,

title = {3024. An Unmanned Spacecraft Subsystem Cost Model for Advance Mission Planning},

author = {George Madrid},

url = {https://www.sawe.org/product/paper-3024},

year  = {2000},

date = {2000-06-01},

booktitle = {59th Annual Conference, St. Louis, Missouri, June 5-7},

pages = {18},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {St. Louis, Missouri},

abstract = {This paper reports on the development of a parametric cost model that is being built at JPL to estimate costs of future, deep space, robotic science missions. Because of the changes in the mission implementation process and technology changes, the model is being built in a dramatically different manner than past models which have had access to a data base that drew heavily on the correlation between mass and actual costs. Instead, the data base is based on the results of an interdisciplinary team of technical experts that make up the core team that assesses new proposals as they are being planned under the new business process being instituted at JPL. The model is then validated against actual mission costs as the projects are implemented. The discussion will provide a summary of this new process as it relates to the development of the model, some of the details of the model itself, and the status of its validation and plans for the future.},

keywords = {19. Weight Engineering - Spacecraft Estimation},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3003,

title = {3003. Evaluation of Equivalent Laminated Plate Solution (ELAPS) in HSCT Sizing},

author = {Steven Stone and Joseph Henderson and Mark Nazari and William Boyd and Bradley Becker and Kumar Bhatia and Gary Giles and Gregory Wrenn},

url = {https://www.sawe.org/product/paper-3003},

year  = {2000},

date = {2000-06-01},

booktitle = {59th Annual Conference, St. Louis, Missouri, June 5-7},

pages = {12},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {St. Louis, Missouri},

abstract = {The motivation for evaluating ELAPS was to determine its suitability as a quick and reliable tool for conceptual and early preliminary design. The expectation was that ELAPS would predict a better structural weight than parametric weight equations since its weight is determined from structural optimization with both strength and flutter constraints. An additional motivation was to eventually utilize the functional representation of ELAPS in shape optimization. Results from the current version of ELAPS were compared against Elfini. The comparisons included static displacements and stresses, natural vibration frequencies and mode shapes, strength optimization, flutter optimization, and simultaneous strength and flutter optimization. Elfini is a mature, well-understood, FEM tool with many years of development effort behind it. Although previous studies have proven the merits of ELAPS for preliminary structural analysis, little research has been accomplished to formally test an ELAPS based flutter optimization. Optimization with strength constraints worked well and provided final weights comparable to Elfini. But the flutter optimization, and simultaneous strength and flutter optimizations converged to significantly different weights. This could partly be attributable to analytical and model differences. There were differences of up to 10% in a few of the first 10 modal frequencies, primarily due to disagreement in stiffness for the HSCT uniform gauge wing. Thus, for ELAPS to provide an attractive option for structural sizing and shape optimization, there needs to be further investments in (1) improving ELAPS? static stiffness correlation with FEM?s, (2) developing an automated parametric input/output graphical interface for ELAPS, (3) improving the robustness of the ELAPS structural representation, (4) improving the computational efficiency of ELAPS and its associated optimization system, and (5) developing ELAPS flutter and shape optimization capabilities In some sense, it is unfair to compare ELAPS with mature FEM codes with years of development effort. However, unless significant improvement to ELAPS is made soon, it will be difficult for ELAPS to compete with the rapid automation of FEM codes for simplified analysis and design.},

keywords = {10. Weight Engineering - Aircraft Design},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2462,

title = {2462. Effect of Control Surface Balance on Flutter},

author = {M Scheulen},

url = {https://www.sawe.org/product/paper-2462},

year  = {1999},

date = {1999-05-01},

booktitle = {58th Annual Conference, San Jose, California, May 24-26},

pages = {16},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {San Jose, California},

abstract = {Mass properties' engineers often are concentrating on creating and maintaining the most accurate and current weight database possible on our aircraft or system. They tend to lose sight of why accurate weight data is important. While having accurate weight data is intrinsically valuable, it can have a major impact on design decisions and even on the viability of a design. Some systems are more sensitive to changes in weight and center of gravity than others. One of the critical elements in the design of aircraft is 'flutter modes'. Every moving body has vibration frequencies. It is important to avoid coupling frequency modes in the airplane components. This can have catastrophic results, including loss of property and lives. Excessive vibration can result in metal fatigue, even without catastrophic failure. It is important that accurate weight and balance data be available to design engineers early in a program. Many problems can be avoided if a potential flutter situation is identified early in a program. An important way the mass properties' engineer can assist in preventing flutter is by working closely with loads and flutter engineers to optimize the control surface balance. Parametric studies are run by loads and flutter engineers to determine the optimal balance weight and location to achieve no coupling of vibration modes. The mass properties' engineer needs to assure that the mass properties' data provided for future analyses reflects this optimal value and the system balance about its hinge line is within the limits established.},

keywords = {10. Weight Engineering - Aircraft Design},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2410,

title = {2410. Aircraft Structural Mass Property Prediction Using Conceptual-Level Structural Analysis},

author = {M G Sexstone},

url = {https://www.sawe.org/product/paper-2410},

year  = {1998},

date = {1998-05-01},

booktitle = {57th Annual Conference, Wichita, Kansas, May 18-20},

pages = {16},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Wichita, Kansas},

abstract = {This paper describes a methodology that extends the use of the Equivalent Laminated Plate Solution (ELAPS) structural analysis code from conceptual-level aircraft structural analysis to conceptual-level aircraft mass property analysis. Mass property analysis in aircraft structures has historically depended upon parametric weight equations at the conceptual design level and Finite Element Analysis (FEA) at the detailed design level. ELAPS allows for the modeling of detailed geometry, metallic and composite materials, and non-structural mass coupled with analytical structural sizing to produce high-fidelity mass property analyses representing fully configured vehicles early in the design process. This capability is especially valuable for unusual configuration and advanced concept development where existing parametric weight equations are not applicable and FEA is too time consuming for conceptual design. This paper contrasts the use of ELAPS relative to empirical weight equations and FEA. ELAPS modeling techniques are described and the ELAPS-based mass properly analysis process is detailed. Examples of mass property stochastic calculations produced during a recent systems study are provided This study involved the analysis of three remotely piloted aircraft required to carry scientific payloads to very high altitudes at subsonic speeds. Due to the extreme nature of this high-altitude flight regime, few existing vehicle designs are available for use in performance and weight prediction. ELAPS was employed within a concurrent engineering analysis process that simultaneously produces aerodynamic, structural, and static aeroelastic results for input to aircraft performance analyses. The ELAPS models produced for each concept were also used to provide stochastic analyses of wing structural mass properties. The results of this effort indicate that ELAPS is an efficient means to conduct multi-disciplinary trade studies at the conceptual design level.},

keywords = {23. Weight Engineering - Structural Estimation},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2406,

title = {2406. Advanced Fuselage Weight Estimation for the New Generation of Transport Aircraft},

author = {A Schmidt and M Lapple and R Kelm},

url = {https://www.sawe.org/product/paper-2406},

year  = {1997},

date = {1997-05-01},

booktitle = {56th Annual Conference, Bellevue, Washington, May 19-21},

pages = {48},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Bellevue, Washington},

abstract = {The airlines are forced to use efficient aircraft due to the hard competition in air traffic. Changes in the airline network, the limited number of slots and the growing rates of passenger and freight require aircraft with high transport performance. This leads to aircraft configurations with high passenger and freight capacities. The fuselage geometry for these types of aircraft can diverge from the conventional design. Also the ongoing studies for the second generation of supersonic aircraft show fuselage designs and physical effects of a new quality. Weight estimations for the resulting new fuselage shapes (e.g. double deck or area ruled configurations) are still a challenging task. Accurate weight prognosis without powerful software tools is becoming an almost hopeless goal. A precise and reliable fuselage weight estimation tool is basis for the assessment of the viability of a new aircraft and has therefore a direct influence on the project. Since the knowledge about the design in the pre-development phase is very limited the software has to include multidisciplinary interactions between loads, structure, and materials. This paper details the process of the fuselage weight estimation method used in the weights prognosis department at Daimler-Benz Aerospace Airbus. Based on simple input data the software creates a numeric 3-D model of the exposed fuselage surface. The position and size of cutouts can be defined by the program user. In the loads module the introduction of external forces and the calculation of internal loads (due to mass distributions of pay-load, systems and structure) are considered. Certification rules, manufacturing procedures, material/structural fatigue and flight/mission envelopes are taken into account. The structure weight calculation is based on classical theories for strength and stability. For the inclusion of the elastic behavior of the fuselage the structural deformation is calculated by the software. The software tool FAME-F (Fast and Advanced Mass Estimation of Fuselage) is described with emphasis on the multidisciplinary character of the computer approach. This approach allows for fast parametric studies and determination of sensitivities. The development of the software tool FAME-F shows how weight engineering can contribute to the essential reduction of aircraft developing time and costs.},

note = {L. R. 'Mike' Hackney Award},

keywords = {23. Weight Engineering - Structural Estimation, Mike Hackney Best Paper Award},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2322,

title = {2322. Artificial Intelligence and Parametric Cost Analysis},

author = {J J Gilliland},

url = {https://www.sawe.org/product/paper-2322},

year  = {1996},

date = {1996-06-01},

booktitle = {55th Annual Conference, Atlanta, Georgia, June 3-5},

pages = {11},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Atlanta, Georgia},

abstract = {The need for reliable parametric cost information in the early design stage is paramount in both the commercial and military aircraft industries. This cost information is typically used for establishment of market prices, design-to-cost targets and decision support for evaluation of bid decisions and proposals. Northrop Grumman' s Commercial Aircraft Division (CAD) has combined Artificial Intelligence techniques and Parametric Cost Analyses to provide our management the opportunity to make informed decisions regarding the cost of an aircraft or aircraft component in the concept development or requirements phase of a program. This paper is presented to show an overview of CAD's method of Artificial Intelligence and Parametric Analysis techniques already in use.},

keywords = {29. Weight Value-Of-Pound},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2286,

title = {2286. Benefits of Parametric Mechanical Design Weight Scaling Decks for Advanced Aircraft Turbomachinery},

author = {J W Rudder},

url = {https://www.sawe.org/product/paper-2286},

year  = {1995},

date = {1995-05-01},

booktitle = {54th Annual Conference, Huntsville, Alabama, May 22-24},

pages = {19},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Huntsville, Alabama},

abstract = {To allow rapid turnaround of weight prediction for advanced aircraft programs, there is a need to be able to down-select concepts with little or no design effort. This improvement comes from application of lessons learned from past deigns and an understanding of how the design is affected by changes in performance. The development of weight decks improve the Weapon System Contractor?s capability to estimate the propulsion system weight effects to meet their mission and performance requirements. The deck allows for a wide range of parameters to be addressed with less time and expense. It also expands the ability to evaluate near and far term technologies on a variety of engine baselines. This paper will discuss the requirements and structure of an Advanced Aircraft Turbomachinery Weight Scaling Parametric with the utilization of a Mechanical Design Routine that establishes the baselines. The following subjects will be discussed in detail to familiarize the reader with the methodology and benefits of Advanced Aircraft Turbomachinery Weight Scaling Decks. What is a Weight Parametric Deck? Mechanical Design Routine Scaling Factors and Switches Technology Methodology and Parametric Integration Effective Deck Flow Benefits to the Deck User and Developer Specific comparisons will be made to the current decks that are being used on advanced programs like JAST and STOVL. This will gave an actual program input/output and program structure as a reference tool.},

keywords = {25. Weight Engineering - System Estimation},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2225,

title = {2225. VTOL/SP, a Vertical Takeoff and Landing Vehicle Synthesis Program},

author = {P P Camacho and P W Scott},

url = {https://www.sawe.org/product/paper-2225},

year  = {1994},

date = {1994-05-01},

booktitle = {53rd Annual Conference, Long Beach, California, May 23-25},

pages = {9},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Long Beach, California},

abstract = {VTOL/SP is an MDC proprietary vehicle synthesis program developed specifically for vertical takeoff and conventional fixed-wing cruise aircraft. The method solves for the design optimization parameter (mission design gross weight) from a set of governing equations for the entire aircraft. It is set up to run interactively, so that solutions can be obtained quickly. The program has been used for parametric studies of the Advanced Technology Transport (ATT) and Special Operations Forces (SOF) aircraft. In-house trade studies are included to demonstrate the capabilities of the program.},

keywords = {11. Weight Engineering - Aircraft Estimation},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2218,

title = {2218. Non-Weight Based Cost Modeling},

author = {C J Meisl},

url = {https://www.sawe.org/product/paper-2218},

year  = {1994},

date = {1994-05-01},

booktitle = {53rd Annual Conference, Long Beach, California, May 23-25},

pages = {16},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Long Beach, California},

abstract = {This paper discusses the advantages of non-weight based cost models and uses launch vehicle rocket engine cost modeling as an example. Top level parametric cost models were generated for pump-fed liquid bipropellant booster and upper stage rocket engines in the 20 Klbs to 2000 Klbs thrust class. The models cover production and full scale development costs and are based on thorough engineering analysis, not regression analysis, using data from historical rocket engines, potential engine derivatives and proposed new engine concepts. The models depend on thermodynamic cycle, propellant type, thrust level, engine complexity, engine maturity and other design parameters. The models are simple cost estimating relationships (CERs) with a transparent rationale and an accuracy of 10 to 30%, depending on the engineering expertise used in the generation of the input variables. The format of the models and the rationale behind them are given in this paper. The cost models make use of adjective and objective parameters. For the adjective inputs, metric scales are given to convert them into numerical values. The adjective inputs require good engineering understanding of rocket engine design and manufacturing principles. Several programmatic and manufacturing process improvement factors are incorporated to extend the applicability of the historical data based cost models to new reusable or expendable advanced performance and/or to low cost engine concepts. The validity and reasonableness of the cost models were successfully checked against detailed cost data of the Space Transportation Main Engine (STME) and against current manufacturing and programmatic analysis results of new engines. A comparative (non-quantitative) evaluation of these new rocket engine cost models with existing weight based models such as TRANSCOST, PRICE-H predictions and a Tecolote Research Inc. originated model is also contained in the paper.},

keywords = {29. Weight Value-Of-Pound},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2156,

title = {2156. Cost and Weight: When More is Less, and Less is More},

author = {R L Webb},

url = {https://www.sawe.org/product/paper-2156},

year  = {1993},

date = {1993-05-01},

booktitle = {52nd Annual Conference, Biloxi, Mississippi, May 24-26},

pages = {18},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Biloxi, Mississippi},

abstract = {Physical characteristics associated with proposed new products are often used as a basis for estimating their cost. In the aerospace industry in particular, parametric cost analysis (as this method is commonly called) is mostly used to develop rough order of magnitude estimates of alternative new systems during the conceptual development phase of the life cycle. Mass properties (weight) in particular have traditionally demonstrated a relatively high positive correlation to cost and have been utilized in developing parametric estimates. While the correlation between weight and cost is generally recognized, it is often misunderstood. In today's cost-conscious environment, weight-based parametric cost analyses have come under criticism as a means for estimating and comparing alternative systems. The criticisms center on two primary reasons. First, the positive correlation (increasing weight increases cost) appears to negate cost reduction approaches which trade increased weight for reduced cost, such as increased margins or using less expensive materials and fabrication processes. Second, using Cost Estimating Relationships (CERs) based on historical data necessarily reflects the high cost of current standard business practices. Estimating new systems using cost models based on old systems tends to perpetuate the current high cost environment in a circular trap of self fulfilling prophecies. By itself, the estimating process leaves no room for the injection of cost reducing changes, or New Ways of Doing Business (NWDB). Much of the substance of these criticisms stems from a misunderstanding of the philosophy and proper application of weight-based estimating methods. Proper evaluations of such things as weight for cost trades can only be made when the alternatives are compared on an ''apples-to-apples,'' or equal level of performance basis. Changes in materials and processes change the basis of the relationship between weight and cost. Adjustments must be made to properly account for these changes. Estimates of the cost impacts of NWDB are most credibly made when a clear, traceable path from an historically based point of departure is drawn. Historically based CERs offer such a point of departure, which, when combined with innovative estimating techniques, can provide traceable, and thus credible, estimates incorporating NWDB. This paper describes ways in which parametric techniques can account for the trading of weight for cost and the introduction of NWDB. The techniques are illustrated with example applications of weight-based CERs used in a structures material selection trade study and the use of NWDB in the manufacturing process.},

keywords = {29. Weight Value-Of-Pound},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2117,

title = {2117. PAYCOS, a Multidisciplinary Sizing Code},

author = {L Edington},

url = {https://www.sawe.org/product/paper-2117},

year  = {1992},

date = {1992-05-01},

booktitle = {51st Annual Conference, Hartford, Connecticut, May 18-20},

pages = {24},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Hartford, Connnecticut},

abstract = {PAYCOS is a computer code developed at Lockheed Missiles and Space Company (LMSC) to rapidly perform concept sizing, concept evaluation, and associated trade studies for supersonic and hypersonic maneuvering vehicles. PAYCOS is a multidisciplinary analysis code that allows the engineer to determine the best geometric configuration for each design through parametric studies and mathematical optimization. This paper presents a general overview of the code, including a brief discussion of the approach used to develop it. The modular structure of the code is reviewed, and a brief discussion of each module is presented. Input data needed to run the code and output data supplied by it are discussed. The role of mathematical optimization in the solution process is discussed in some detail and examples of this process are presented. Finally, current modifications to the code are described along with potential future modifications and applications.},

keywords = {12. Weight Engineering - Computer Applications},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2110,

title = {2110. A-12 Structural Target Weight Distribution Using the Finite Element Model (FEM)},

author = {S J Zaidel},

url = {https://www.sawe.org/product/paper-2110},

year  = {1992},

date = {1992-05-01},

booktitle = {51st Annual Conference, Hartford, Connecticut, May 18-20},

pages = {13},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Hartford, Connnecticut},

abstract = {The distribution of parametric weight estimates into detail structural component (target) weights is a difficult and time consuming process. Traditional methods use a high percentage of historical data and are not very responsive to advanced structural concepts. More accurate procedures are needed to establish better credibility as well as identify potential overweight areas earlier in an aircraft program. Use of the Finite Element Model (FEM) in distributing structural target weights was applied for the first time at McDonnell Aircraft (MCAIR) on the A-12 Project. The FEM contained the level of detail necessary to establish major structure target weights for the unique aircraft design and also provided traceability back to the strength analyses. Weight factors were derived to adjust the baseline stiffness model to represent detailed target weights. Additionally, the FEM was used as a check on the structural subsection weight distribution between MCAIR and its A-12 partner General Dynamics. The methodology developed has benefited related R&D projects and other aircraft programs (including the F/A-18E/F) which are using the FEM as a weight estimation and control tool. NOTE: Due to the sensitive nature of information related to the A-12 program, this paper has omitted data considered classified or which may give a competitive edge to any of the teams involved in the AX program.},

keywords = {26. Weight Growth},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2046,

title = {2046. Aircraft Weight Confidence Assessment},

author = {M Anderson},

url = {https://www.sawe.org/product/paper-2046},

year  = {1991},

date = {1991-05-01},

booktitle = {50th Annual Conference, San Diego, California, May 20-22},

pages = {14},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {San Diego, California},

abstract = {The purpose of this paper is to present a technique that determines confidence levels of estimated weight data. The paper outlines a procedure and applies it to a fuel system weight breakdown. Using the fuel system example as a guide, determining confidence in an estimated aircraft weight could be found. The initial background and analysis for the method is presented with results of a confidence analysis using a ''bottoms-up'' system estimated weight. This method provides the foundation of a plan for tracking confidence of estimated aircraft weight throughout development Confidence levels can be updated continually and reviewed with management during design development. Design maturity is reflected in the possible variation of the itemized weight used in the models. By combining weight variations of each item and using simulation software, confidence levels for the total group weight can be determined. The paper concludes that confidence levels help set realistic goals, identify areas for possible weight reduction, and identify problem areas in parametric estimates or design/technology maturity.},

keywords = {21. Weight Engineering - Statistical Studies},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2001,

title = {2001. An Approach to Estimating the Cost Impacts of New Ways of Doing Business on the Recurring Cost Space Transportation System},

author = {R L Webb},

url = {https://www.sawe.org/product/paper-2001},

year  = {1991},

date = {1991-05-01},

booktitle = {50th Annual Conference, San Diego, California, May 20-22},

pages = {24},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {San Diego, California},

abstract = {Over the past several years the technical challenges associated with providing transportation to and from space have been met with ever greater efficiency. As space has become more accessible, attention has focused more and more on reducing its high cost. Proposed new space transportation systems such as the Advanced Launch System (ALS), NASP Derived Vehicle (NDV), Single Stage To Orbit (SSTO), and others, all have as a primary stated goal in some form a significant reduction in the recurring cost of providing space transportation on a routine basis. The reduced costs forecast for these new systems are generally projected to be achieved through the introduction of new technologies, different program structures and/or philosophies, or other innovations which deviate from the standard practices, or Business As Usual (BAU), currently employed in providing space transportation. In the initial concept development stages of programs such as these, it falls to the parametric cost analyst to attempt to forecast at a top level the potential magnitude of the recurring cost reductions to be achieved through the incorporation of these innovations, or ''New Ways of Doing Business'' (NWDB). The focus of this paper is to outline a methodology for estimating reductions in the recurring cost of space transportation systems resulting from the introduction of NWDB. The methodology described can be used as a means to develop a traceable, visible, and thus, credible top level estimate of the cost impacts resulting from the incorporation of specific NWDB in the operation of space transportation systems.},

keywords = {29. Weight Value-Of-Pound},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1993,

title = {1993. Parametric Equation Determination: A Relational Database Approach Using Dynamic Views},

author = {J D Munter},

url = {https://www.sawe.org/product/paper-1993},

year  = {1991},

date = {1991-05-01},

booktitle = {50th Annual Conference, San Diego, California, May 20-22},

pages = {13},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {San Diego, California},

abstract = {The process discussed in this paper utilizes INGRES relational database technology to efficiently store and retrieve data used in an engineering process. An INGRES 4GL user frame is used to organize the columns into the desired data sets (views) and to facilitate the engineering analysis. A 3GL ''C'' procedure is used to create the view. These database views may contain several columns from one table or they may contain columns from several tables. The views are created dynamically with the use of pop-up menus and cursor selections. The views are used for data retrieval and are stored for repeated use and/or editing. Advantages of this method over traditional methods are non-duplication of work and facilitated data handling. Additional advantages are the removal of the Database Administrator (DBA) from the ''view'' creation process and added flexibility for the user.},

keywords = {12. Weight Engineering - Computer Applications},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1974,

title = {1974. An Improved Methodology for Estimating Advanced Composite Airframe Weights During Conceptual and Preliminary Design},

author = {M A Jankowski},

url = {https://www.sawe.org/product/paper-1974},

year  = {1990},

date = {1990-05-01},

booktitle = {49th Annual Conference, Chandler, Arizona, May 14-16},

pages = {28},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Chandler, Arizona},

abstract = {Current projections indicate an increased application of advanced composites in next-generation aircraft. With the stringent requirements on improved performance of these aircraft, an early and accurate estimate of the composite e weight is needed for a timely assessment of their performance/mission capabilities. Also, in order to minimize weight driven problems during preliminary design, a more accurate method of estimating the weight of a composite and/or hybrid airframe is needed beginning with conceptual design level. With the emergence of ultra light weight composite utilizing high modulus/strength carbon fibers, the current data base lacks the support of existing aircraft utilizing such materials. As a result, the conventional weight estimation methods for composite airframes are based on parametric relationships, established from correlations of existing metallic aircraft weights, and adjusted by empirical ''Material Factors'' to account for the use of composites. A number of industry-wide studies have used weight ratio methodologies based on existing metallic structures to estimate the weight reductions associated with the use of composites. However, the highly directional/anisotropic properties of these materials lead to different behaviors of these materials in a number of failure modes. As a result, the existing weight ratio methods are invalid and need proper adjustments to account for the unique behavior of composite materials. A modified ''Weight Ratio Methodology'' that could accurately quantify the weight changes due to metal-to composite material substitutions will result in more rationally defined ''Material Factors.'' These rational ''Material Factors'' will allow the evaluation and development of more reliable and comprehensive parametric methods for estimating composite airframe weights of next-generation aircraft. This paper will discuss the development of ''Material Factors'' for a conventional graphite/epoxy system such as AS4/3501-6 as well as emerging high strength/modulus carbon fiber composites currently being evaluated in ''Ultra light weight Airframe'' studies.},

keywords = {11. Weight Engineering - Aircraft Estimation},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1966,

title = {1966. Landing Gear Weight Optimization Using Taguchi Analysis},

author = {R H Wille},

url = {https://www.sawe.org/product/paper-1966},

year  = {1990},

date = {1990-05-01},

booktitle = {49th Annual Conference, Chandler, Arizona, May 14-16},

pages = {24},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Chandler, Arizona},

abstract = {The Taguchi Method provides the weights engineer with an efficient, disciplined approach for determining the primary weight drivers and weight interactions of a parametric study. The Taguchi Method will be used to study several simultaneous geometric variations of an advanced landing gear to arrive at the lightest weight configuration. The Landing Gear Analytical Weight Estimation program (LANGE) will be used to analyze the unique experimental landing gear configurations selected by the Taguchi approach. LANGE is used in the MCAIR weights department as a tool for landing gear weight estimates and parametric studies. These estimates have proved to be accurate and sensitive to changes in geometry, materials, and loads. This paper briefly explains the Taguchi Method and illustrates the approach used in the weight optimization of an advanced landing gear. The results of this study will supply valuable information to the weights engineer and landing gear designers about weight effects from parametric variation of geometric features. In addition, it will illustrate how a preliminary landing gear design could be optimized by applying principles of the Taguchi Method to the analysis of the LANGE program.},

keywords = {11. Weight Engineering - Aircraft Estimation},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1913,

title = {1913. Aluminum Lithium for the F/A-18, Hornet 2000},

author = {J C Johnson},

url = {https://www.sawe.org/product/paper-1913},

year  = {1989},

date = {1989-05-01},

booktitle = {48th Annual Conference, Alexandria, Virginia, May 22-24},

pages = {38},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Alexandria, Virginia},

abstract = {The F/A-18 Hornet 2000, a derivative aircraft for the US Navy, entails a 20% increase in aircraft weight empty due to avionics systems upgrades, survivability improvements, increased wing size, and fuselage lengthening. Weight saving methods evaluated included substituting aluminum lithium for aluminum without detail part redesign. A prerequisite was that the material properties be at least as good as those of the material being replaced. Due to time constraints, a parametric weight increment had to be used for the configuration evaluations. However, as the Hornet 2000 study progressed, it became apparent that a detailed weight analysis was needed to increase confidence in this weight increment. This analysis included three phases. First, a material study determined what alloys, forms, and material properties of aluminum lithium were available. These material properties were compared to those of the aluminum alloys on the F/A-18. The next phase of the study involved merging data from a weight database and a drawing database to obtain a detailed listing of parts which could potentially be changed to aluminum lithium. Once this list was created, individual part weights were added to find a total weight to be converted. Potential weight savings, assuming current day and projected 1990 technology, were then derived using a 9% density reduction. Results of the 1990 technology weight savings were than extrapolated to a projected weight savings for Hornet 2000. The third phase of the study was to create a pictorial summary of the potential parts which could be changed to aluminum lithium based on 1990 technology.},

keywords = {27. Weight Reduction - Materials},

pubstate = {published},

tppubtype = {inproceedings}

}