SAWE Technical Papers

@inproceedings{3811,

title = {3811. Parametric Weight Substantiation And Uncertainty Quantification For Aircraft Design},

author = {Andy Walker},

url = {https://www.sawe.org/product/3811-parametric-weight-substantiation-and-uncertainty-quantification-for-aircraft-design/},

year  = {2024},

date = {2024-05-22},

booktitle = {83rd International Conference, virtual (2024)},

pages = {46},

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

organization = {SAWE},

abstract = {Creating and substantiating weight estimation methods for future aircraft design has been completed using open-source data. Legacy best-practices were explored in corelating weight estimating relationships for configurations relating to manned fighters, carrier-based fighters, jet transports, business jets, military intelligence/ surveillance/ reconnaissance (ISR), and general aviation. Statistical methods were used to validate that each parametric method follows a normal, Gaussian distribution. This paper also makes some novel observations regarding statistical weight regressions, including: the fallacy of removing data points in regressions, the good and bad side of adding weight growth margins, employing detailed vs coarse weight method calibration factors, and how legacy aircraft validation helps in the big picture but hurts in the details.},

keywords = {Aircraft, Other Engineering},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3795,

title = {3795. Aerostructural Weight Estimation for a Transonic Truss-Braced Wing Using the Higher-Fidelity Conceptual Design and Structural Optimization Tool},

author = {Zachary Windous and Jesse R. Quinlan},

url = {https://www.sawe.org/product/paper-3795},

year  = {2023},

date = {2023-05-20},

urldate = {2023-05-20},

booktitle = {82nd Annual Conference, Cocoa Beach, Florida},

pages = {11},

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

address = {Cocoa Beach, Florida},

abstract = {Continued development and enhancements of the Higher-fidelity Conceptual Design and structural optimization (HCDstruct) tool have been driven largely by advanced aircraft concepts of interest to NASA. While previous versions of HCDstruct were limited to hybrid wing body (HWB) and generalized tube and wing (TW) aircraft concepts, the latest version of HCDstruct supports the analysis of Truss-Braced Wing (TBW) aircraft concepts, enabling users to model both high and low wing configurations as well as strut and jury geometries parametrically. Additionally, new methods for modeling advanced composite materials within HCDstruct have been implemented. These recent tool enhancements were demonstrated for an independent assessment of the NASA/Boeing SUGAR Phase VI Mach 0.8 Transonic Truss-Braced Wing (TTBW) concept.},

keywords = {Aircraft},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3709,

title = {3709. A Wing Weight Estimation Method Based on Wing-box Beam Design},

author = {Lu Bai and Zhi Deng and Xintan Zhang and Ming Xia and Jianli Wang},

url = {https://www.sawe.org/product/paper-3709},

year  = {2020},

date = {2020-07-01},

urldate = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {12},

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

address = {Virtual Conference},

abstract = {In this paper, a wing weight estimation method for transport aircraft is presented. By establishing related computational framework, a wing-box model is developed based on wing-box beam design, from where a wing weight estimation method is derived. The key steps of this work include parametric modeling based on structural model simplification, aerodynamic study, finite element method, and aeroelastic analysis. The influence of the mounted pylon has been considered for the wing-box sizing. This method has been validated using data of two different transport aircrafts, which shows that this method is robust and efficient. Outcome of this paper could be rapidly integrated in the conceptual design phase.},

keywords = {11. Weight Engineering - Aircraft Estimation, 23. Weight Engineering - Structural Estimation},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3739,

title = {3739. Rotorcraft Mass Assessment in an Integrated Design Framework},

author = {Dominik B. Schwinn and Peter Weiand},

url = {https://www.sawe.org/product/paper-3739},

year  = {2020},

date = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {15},

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

address = {Virtual Conference},

abstract = {Mass estimation is an essential discipline in the design process of aeronautical vehicles. The maximum take-off mass determines most other design parameters and should therefore be estimated sufficiently precise from the beginning. In the conceptual design phase fast analyses are required in order to allow trade-off studies. In general, this phase is dominated by the use of analytical and statistical methods. At the end of this design stage, a basic external layout has been elaborated and basic design parameters have been determined.During the subsequent preliminary design stage, physics based higher fidelity methods are applied to further elaborate the design and to establish an internal configuration. The constantly increasing computational power allows comparably fast analyses in this design stage that may alter the configuration established in the conceptual design stage.Particular challenges in this design approach arise with unconventional configurations, such as compound rotorcraft, or with different propulsion systems to be integrated, for instance electric or hybrid systems, because of a lack of sufficient statistical data.The German Aerospace Center (DLR) has established the integrated design environment IRIS (Integrated Rotorcraft Initial Sizing) to allow an assessment of virtual rotorcraft configurations. It covers the conceptual and parts of the preliminary design stage and uses the data model CPACS (Common Parametric Aircraft Configuration Schema) for the parametric rotorcraft description.Component masses in IRIS are estimated using various statistical methods during the conceptual design stage. Finite Element (FE) methods are applied in the preliminary design phase to allow a more precise estimation of the structural mass which may influence the maximum take-off mass and therefore the performance characteristics calculated in the conceptual design stage.This paper introduces the design environment IRIS, and in particular the PANDORA framework (Parametric Numerical Design and Optimization Routines for Aircraft) which is used for the statistical estimation of the rotorcraft component masses and the structural sizing process to determine the fuselage mass.},

keywords = {10. Weight Engineering - Aircraft Design, 21. Weight Engineering - Statistical Studies, 24. Weight Engineering - System Design},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3729,

title = {3729. Application of SAWE Course 'Developing Basic Parametric Methods' to Nacelle Weight Estimating},

author = {Doug Fisher},

url = {https://www.sawe.org/product/paper-3729},

year  = {2019},

date = {2019-05-01},

booktitle = {78th Annual Conference, Norfolk, VA},

pages = {17},

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

address = {Norfolk, Virginia},

abstract = {This paper details how the learning contained in SAWE course 'Developing Basic Parametric Methods' was applied at Collins Aerospace for estimating nacelle weights of new commercial and business jet aircraft. Collins has decades of experience developing nacelles and a large database of historical weight data, but has not effectively leveraged that data into better weight estimating tools. Learning from this course was applied to develop improved methods of estimating the weight of nacelles for new product proposals. This has allowed us to not only provide better weight estimates but also better understand the limits of our data and estimating methods.},

keywords = {10. Weight Engineering - Aircraft Design, 11. Weight Engineering - Aircraft Estimation, 21. Weight Engineering - Statistical Studies},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3716,

title = {3716. A Methodology of Determining Parametric Equations from Data with a Worked Example},

author = {David Laurence Hansch},

url = {https://www.sawe.org/product/paper-3716},

year  = {2019},

date = {2019-05-01},

booktitle = {78th Annual Conference, Norfolk, VA},

pages = {25},

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

address = {Norfolk, Virginia},

abstract = {The method of using multiple regression to determine parametric weight equations is discussed. A worked example based on 1930s to 1940s US submarines is given. In an appendix, the resulting equations are used for comparative naval architecture with contemporary British and German designs.},

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

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3687,

title = {3687. An Updated Initial Parametric Weight Equation Compendium},

author = {David Hansch},

url = {https://www.sawe.org/product/paper-3687},

year  = {2017},

date = {2017-05-01},

booktitle = {76th Annual Conference, Montreal, Canada},

pages = {50},

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

address = {Montreal, Canada},

abstract = {When developing the initial weight estimate for a new vessel, the weight engineer or naval architect can produce his or her estimate either by scaling from a known, similar vessel, or by taking the weights of each portion of the vessel from parametric equations or by some combination of these two methods. The preferred source of a parent vessel to scale from or the data from which a parametric equation is derived is the past vessels designed by the naval architect's own firm; however, sometimes the firm may not have suitable designs in its portfolio to base a new design weight estimate upon. This paper seeks to collect as many previously published parametric weight equations for as wide a collection of vessel types as possible in order to provide a convenient reference for the times the naval architect's own data is insufficient to complete a weight estimate.This paper is not intended to be the definitive source of parametric weight equations, rather, the goal is to collect a critical mass of equations across the range of vessel types to start the conversation on the relative merits of the various equations and hopefully elicit new up-to-date equations from others. Ideally discussers will add equations based on their own data in addition to discussing the merits of those collected here. The end goal is the production of a SNAME T&R Bulletin, however much additional validation, updating and discussion is required to take the current paper to the point where it could be considered as a true draft for such a bulletin.In all cases, the reader is encouraged to consult the original source and attempt independent validation before using any of the equations collected herein.},

keywords = {Marine},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3660,

title = {3660. Development of a Conceptual Flight Vehicle Design Weight Estimation Method Library},

author = {Andy Walker},

url = {https://www.sawe.org/product/paper-3660},

year  = {2016},

date = {2016-05-01},

booktitle = {75th Annual Conference, Denver, Colorado},

pages = {171},

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

address = {Denver, Colorado},

abstract = {The state of the art in estimating the volumetric size and mass of flight vehicles is held today by an elite group of engineers in the Aerospace Conceptual Design Industry. This is not a skill readily accessible or taught in academia. To estimate flight vehicle mass properties, many aerospace engineering students are encouraged to read the latest design textbooks, learn how to use a few basic statistical equations, and plunge into the details of parametric mass properties analysis. Specifications for and a prototype of a standardized engineering 'tool-box' of conceptual and preliminary design weight estimation methods were developed to manage the growing and ever-changing body of weight estimation knowledge. This also bridges the gap in Mass Properties education for aerospace engineering students. The Weight Method Library will also be used as a living document for use by future aerospace students. This 'tool-box' consists of a weight estimation method bibliography containing unclassified, open -source literature for conceptual and preliminary flight vehicle design phases. Transport aircraft validation cases have been applied to each entry in the AVD Weight Method Library in order to provide a sense of context and applicability to each method. The weight methodology validation results indicate consensus and agreement of the individual methods. This generic specification of a method library will be applicable for use by other disciplines within the AVD Lab, Post- Graduate design labs, or engineering design professionals.},

note = {Mike HackneyBest Paper Award - 2016},

keywords = {10. Weight Engineering - Aircraft Design, 11. Weight Engineering - Aircraft Estimation, Mike Hackney Best Paper Award},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3633,

title = {3633. Methods Used for Tracking, Validating, and Reporting the Weight of Operating Space Items (OSI) and Storeroom Items (SRI)},

author = {R. Alan Bird},

url = {https://www.sawe.org/product/paper-3633},

year  = {2015},

date = {2015-05-01},

booktitle = {74th Annual Conference, Alexandria, Virginia},

pages = {19},

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

address = {Alexandria, Virginia},

abstract = {Many times, items are listed as 'Items to Deduct' during the Deadweight Survey, which, according to the Expanded Ship Work Breakdown Structure (ESWBS), are actually part of Lightship. Due to misconceptions and/or errors, the Deadweight Survey is not accurate when compared to the Mass Properties Reports. The largest confusion is with the definition of Operating Space Items (OSI), Storeroom Items (SRI), and General Use Consumable List (GUCL) items. Another issue is that OSI is most often completely missed in the early stages of a weight estimate and those items are also among the most challenging to get accurate weight values for. Weighing of these items is difficult as these are generally small items and have a high risk of being pilfered or 0damaged, and are therefore not loaded out until delivery. Although arriving late in the weight estimating schedule, getting accurate weights for the 'little things' that make the ship work will benefit the Deadweight Survey / Inclining Experiment, and will also yield valuable data for future parametrically generated weight estimates. This paper shows one method used to accurately capture the weight and the locations on the ships where these items will be.},

keywords = {Marine},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3615,

title = {3615. Application Of A Flexible Wing Modeling And Physical Mass Estimation System For Early Aircraft Design Stages},

author = {Felix Dorbath},

url = {https://www.sawe.org/product/paper-3615},

year  = {2014},

date = {2014-05-01},

booktitle = {73rd Annual Conference, Long Beach, California},

pages = {23},

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

address = {Long Beach, California},

abstract = {State-of-the-art models in preliminary wing design apply physics-based methods for primary structures while using empirical correlations for secondary structures. Using those methods, a detailed optimization such as e.g. rear spar positions or flap size is only possible within a limited design space. Novel structural concepts such as multi-spar flap layouts or the introduction of composite materials cannot be analyzed using statistical methods and require extended higher level structural modeling. 

Therefore, a flexible wing modeling and physical mass estimation system for early aircraft design stages is developed - the WINGmass system. The core of the interdisciplinary tool chain is a central model generator that automatically generates all analysis models from the DLR aircraft data format CPACS (Common Parametric Aircraft Configuration Scheme). For the automatic model generation, a large amount of engineering rules are implemented in the model generator, to reduce the amount of required input parameters and therefore to relieve the aircraft designer. Besides the multi-model generator, the tool chain consist of a structural finite element model (incl. wing primary structures, flaps, flap tracks, ailerons, engine pylon and landing gear), a structural sizing algorithm and loads models for aerodynamic, fuel, landing gear and engine loads. 

The wing mass estimation system is calibrated against real mass values of the wing primary structures and the trailing edge devices of the Airbus A320 and A340-200. The results of the calibrated tool chain are compared to the masses of the primary structures of the B747-100 and the aluminum baseline version of the MD-90-40X. The calibration factors for composite primary structures are derived from the composite version of the MD-90-40X. 

Finally, the benefits of the extended physics-based modeling and the application of the WINGmass system in an interdisciplinary aircraft design environment are shown in an aircraft design study. The objective of this study is to compute the optimal wing shape in terms of mission fuel as a function of the take-off field length. Therefore, a parameter variation of the wing and flap geometry is performed, the engine scaled correspondingly and the mission fuel evaluated.},

keywords = {10. Weight Engineering - Aircraft Design, 23. Weight Engineering - Structural Estimation},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3598,

title = {3598. Improving Structural Weight Estimation of Novel Aircraft Configurations to Enhance Flying Quality Analysis},

author = {Seyyedeh Maryam Moghadasi and Ali Elham and Mark Voskuijl},

url = {https://www.sawe.org/product/paper-3598},

year  = {2013},

date = {2013-05-01},

booktitle = {72nd Annual Conference, St. Louis, Missouri},

pages = {18},

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

address = {Saint Louis, Missouri},

abstract = {Structural weight estimation of novel aircraft configurations, such as a box-wing aircraft, in the conceptual and preliminary design phase is a challenge due to a lack of statistical data. Most of the aircraft performance and handling qualities parameters are strongly influenced by the aircraft weight and inertia. Therefore an accurate weight estimation method is required. The application of existing (statistical) weight estimation methods provides a rather inaccurate and weak estimation for this novel configuration. An alternative is the use of higher fidelity weight estimation methods, which use more physics based calculations and less statistical estimations. 

A novel design framework with various disciplines is developed. In this framework, a parametric aircraft model, a weight estimation method, aerodynamic analysis and flight mechanics analysis are coupled to perform a fully automated design process. The various modules of this design framework create a decision making system so that the aerodynamic and weight estimations for handling quality measurements can take place with high fidelity for different aircraft category during the preliminary and conceptual design process. 

It is demonstrated that the design parameters of the PrP300 are closely coupled and a delicate balance has to be found between the design parameters in order to have adequate handling qualities throughout the flight envelope. Such a trade- off is most likely very difficult, if not impossible to conduct by hand. 

The proposed framework is therefore a powerful tool to support the aircraft design activities and to investigate the handling qualities of an (unconventional) aircraft already in the early design stages. This can lead to a less error design and consequently decrease the cost due to additional design work and extra wind tunnel and flight testing.},

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

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3579,

title = {3579. An Empirical Aero Gas Turbine Preliminary Weight Estimation Method Based On Artificial Neural Networks},

author = {P. Lolis and B. Arumugam Shanmugasundaram and V. Sethi and P. Pilidis},

url = {https://www.sawe.org/product/paper-3579},

year  = {2012},

date = {2012-05-01},

booktitle = {71st Annual Conference, Bad Gögging, Germany},

pages = {12},

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

address = {Bad Gögging, Germany},

abstract = {During the last years the number of parameters involved in the design and selection of an aero engine has greatly increased, making the decision for the most suitable aircraft engine at the preliminary design stage a challenging task. To cope with these requirements multi-disciplinary parametric tools, that perform Techno-economic and Environmental Risk Analysis (TERA) and trade-off studies have been introduced. These tools integrate several packages that model different aspects of the engine, aircraft and mission at the preliminary design stage. One of those is the preliminary weight estimation module, necessary for the aircraft performance, but also for the engine optimisation studies. 

Existing aero gas turbine preliminary weight estimation methods that are publicly available either fail to achieve the necessary accuracy or are complex and time consuming. Moreover, these methods are based on engine databases that are more than 30 years old, rendering them outdated and untrustworthy for recent engines. Therefore, there is a need for a new, more accurate, simple and fast method. 

The ability of empirical methods to better capture aspects that cannot be modelled easily, combined with the availability of data for the whole aero engine weight, led to the development of a new method based on an aero gas turbine database. Take-off thrust, overall pressure ratio, by-pass ratio and year of entry into service are the four key variables influencing the engine weight that were selected for the present study. To analyse the available data Artificial Neural Networks (ANNs) were selected as the most suitable tool, due to their ability to model effectively complex patterns and relations. 

This paper includes an analysis of several possible feedforward backpropagation ANN configurations and their comparison based on accuracy, simplicity and calculation time with the two hidden layer emerging as the most suitable configuration. However, the error achieved is higher than the indicated limit of ~10% for engine optimisation studies. Therefore several improvements are suggested for expansion of the database and alternative configurations that will help reduce the calculated error.},

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

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3562,

title = {3562. Parametric Estimation Of Anchor Handling / Towing Winches},

author = {Stein Bjòrhovde and Runar Aasen},

url = {https://www.sawe.org/product/paper-3562},

year  = {2012},

date = {2012-05-01},

booktitle = {71st Annual Conference, Bad Gögging, Germany},

pages = {13},

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

address = {Bad Gögging, Germany},

abstract = {Anchor Handling Tug vessels (AHT) are ships built to handle anchors for oil rigs, in addition to towing the platforms into position and in some cases operate as Emergency Rescue and Recovery Vessel (ERRV). Compared to ordinary offshore supply vessels, AHTs are characterized by large winches for towing and anchor handling, open stern for landing of anchors and a large bollard pull. 

The winch packages for anchor handling tug vessels are large and heavy constructions with weight that varies from 150 to 900 tonnes and may represent as much as 15% of the lightship weight for the vessel. In addition to significant weight, it also influences a lot on the vertical center of gravity (VCG) og thereby the stability of the ship. Also the longitudinal center of gravity (LCG) is significantly influenced by the layout and positioning of this equipment. 

Experience shows that it might be difficult to identify reliable weight and center of gravity (CoG) for this special made equipment from fabricators and suppliers in an early design phase. Based on this we want to study which parameters are relevant for estimating weight and CoG for anchor handling / towing winches, and how these parameters can be combined in mathematical formulas that can be used in regression based estimation. 

The advantage of using regression is among others the quantification of uncertainty (standard deviation) related to each specific estimation method and thereby the possibility to decide which methods that are the most precise, and to evaluate whether parametric estimation can be used at all. An evaluation of the uncertainty requirements will be performed as well. 

Stein Bjòrhovde is one of the founders and head of development of BAS Engineering. Mr. Bjòrhovde has a Master of Science Degree in Ship Design, and has been developing the weight engineering software ShipWeight since 1993. He has also been involved in development of other weight control software, in addition to being a consultant doing weight estimation and monitoring in the offshore industry. He has more than 15 years experience in weight estimation of new ship designs for several Norwegian and international ship designers and yards. 

Runar Aasen is one of the founders and technical sales manager of BAS Engineering, a SAWE corporate member. Mr. Aasen has a Master of Science Degree in Ship Design, has been extensively involved in the development of weight engineering software and user support for the last fourteen years, and became a SAWE Fellow Member in 2006. Since 1996, BAS Engineering has provided ship designers and builders around the world with naval architecture and mass properties support. BAS Engineering's ShipWeight software entered the US market for the first time in 1998 and has since been adapted by major US shipyards and designers.},

keywords = {25. Weight Engineering - System Estimation, 35. Weight Engineering - Offshore},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3547,

title = {3547. Implementation of a Tool Chain for Extended Physics-Based Wing Mass Estimation in Early Design Stages},

author = {Felix Dorbath and Björn Nagel and Volker Gollnick},

url = {https://www.sawe.org/product/paper-3547},

year  = {2012},

date = {2012-05-01},

booktitle = {71st Annual Conference, Bad Gögging, Germany},

pages = {21},

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

address = {Bad Gögging, Germany},

abstract = {The state-of-the-art methods in preliminary wing design are using models employing physics-based methods for primary structures while using empirical correlations for secondary structures. Using those methods, detailed optimization as e.g. rear spar positions or flap size is only possible within a limited design space. Novel structural concepts such as multi-spar flap layouts or the introduction of composite materials cannot be analyzed using statistical methods and require extended higher level structural modeling. Therefore an interdisciplinary tool chain is developed for extended physics-based wing mass estimation. The tool chain consists of the following components: one central model generator, a structural finite element model, a structural sizing algorithm and loads models for aerodynamic, fuel, landing gear and engine loads. The structural finite element wing model consists of the following main parts: wing box, fixed trailing edge devices, movable trailing edge devices, spoilers, landing gears and engine pylons. The model generator is able to create several different kinds of track kinematics, covering most of the track types used in state-of-the-art aircrafts. To make the complexity of the model generation process feasible for one aircraft designer, a knowledge based approach is chosen. Therefore the central model generator requires a minimum set of easy-to- understand input parameters. This enables the aircraft designer to focus on the design and not on calculating input parameters. To include the tool chain in a wider multidisciplinary aircraft design environment, the aircraft parameterization CPACS (Common Parametric Aircraft Configuration Scheme) is used as central data model for input and output. The developed tool chain is implemented as flexible as possible to enable the designer to analyze also novel structural concepts or wing configurations. On wing configurational level, the tool chain can handle most types of different wing concepts, such as e.g. blended wing bodies, strut-braced wings and box wings. On the structural concepts side, the tool chain is able to handle various different rib and spar layouts and different materials (incl. composites).},

note = {Mike Hackney Best Paper Award},

keywords = {10. Weight Engineering - Aircraft Design, 23. Weight Engineering - Structural Estimation, Mike Hackney Best Paper Award},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3505,

title = {3505. Early~Stage~Weight~and~Cog~Estimation~Using~Parametric Formulas~and~Regression~on~Historical~Data},

author = {Runar Aasen and STEIN BJORHOVDE},

url = {https://www.sawe.org/product/paper-3505},

year  = {2010},

date = {2010-05-01},

booktitle = {69th Annual Conference, Virginia Beach, Virginia},

pages = {35},

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

address = {Virginia Beach, Virginia},

abstract = {Estimation~ of~ weight~ and~ center~ of~ gravity~ is~ an~ essential~ task~ in~ the~ design~ phase~ of~ a~ vessel,~ and~ the~ 

quality~ of~ this~ work~ will~ be~ crucial~ for~ the~ success~ of~ the~ project.~ It~ is~ important~ to~ have~ the~ best~ possible~ 

estimate~ for~ total~ lightship~ weight,~ but~ when~ it~ comes~ to~ construction~ and~ installation~ there~ will~ be~ a~ 

demand~ for~ detailed~ budgets.~ A~ certain~ detail~ level~ for~ the~ weight~ budget~ will~ also~ make~ it~ easier~ to~ find~ 

the~reasons~for~any~deviations~that~may~occur~during~the~monitoring~phase.~ 

The~ use~ of~ parametric~ estimation~ based~ on~ several~ reference~ ships~ and~ regression~ lines~ has~ traditionally~ 

been~ characterized~ as~ too~ demanding,~ because~ of~ time~ demands~ as~ well~ as~ complexity.~ This~ article~ will~ 

describe~ some~ assumptions~ and~ methods~ that~ make~ it~ possible~ and~ preferable~ to~ use~ parametric~ 

estimation~ on~ a~ regular~ basis~ when~ designing~ and~ building~ a~ ship,~ either~ by~ the~ use~ of~ built-in~ formulas~ 

and~ graphs~ found~ in~ spreadsheets,~ or~ by~ the~ use~ of~ database~ related~ weight~ control~ systems~ like~ 

ShipWeight.~ This~ article~ will~ discuss~ topics~ like~ breakdown~ structures,~ methods,~ selection~ of~ coefficients,~ 

selection~ of~ detail~ level,~ reporting~ and~ exporting~ of~ results,~ together~ with~ design~ changes~ and~ re- 

estimation.},

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

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3432,

title = {3432. Weight Estimation of a Two-Seat Turboshaft Equipped Helicopter Transmission Drive System},

author = {Frank Buysschaert and Dimitri Vanbellinghen and Patrick Hendrick},

url = {https://www.sawe.org/product/paper-3432},

year  = {2007},

date = {2007-05-01},

booktitle = {66th Annual Conference, Madrid, Spain},

pages = {38},

publisher = {Society of Allied Weight Engineers},

address = {Madrid, Spain},

organization = {Society of Allied Weight Engineers},

abstract = {A Belgian industrial company, Winner scs, supported by the Walloon Region, has charged our service at the Free University of Brussels (ULB) to design a two seat helicopter powered by a small kerosene-fueled turboshaft engine based on their previous piston driven single seat helicopter. The helicopter is intended to be used mainly for training purposes but also for leisure flight. It would be certified in the CNSK category issued by the French DGAC. The final product must be a low cost option for potential helicopter customers. In order to reduce cost and complexity, the transmission system of the helicopter needs to be very simple and robust. Its weight should be minimized for optimum helicopter performance without compromising safety. This paper describes the considered transmission system architecture and elucidates its weight estimation with the several aspects involved. Since the helicopter design parameters are continuously evolving, a parametric approach will be used throughout this paper.},

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

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3422,

title = {3422. Weight Prediction of UAV Structures and Subsystems Using Parametric Design Methods},

author = {Mario Zimmerman},

url = {https://www.sawe.org/product/paper-3422},

year  = {2007},

date = {2007-05-01},

booktitle = {66th Annual Conference, Madrid, Spain},

pages = {25},

publisher = {Society of Allied Weight Engineers},

address = {Madrid, Spain},

organization = {Society of Allied Weight Engineers},

abstract = {For larger UAVs with more than 500 kg MTOM, technologies and assembly methods similar to man-carrying systems are used. These allow the use of known preliminary design methods according to Raymer, Roskam, or Stinton. In the case of smaller vehicles, the use of empiric equations made for man-carrying systems, most of the time, cause significant errors due to unscale-effects. Among other effects, this is based on a smaller decrease in size of connecting elements when decreasing overall part dimensions. Bonds of ribs with the outer skin can make up to 50% of the mass at small sizes. At reduced dimensions, breakouts for mass reduction cannot be made, which causes an unproportional mass increase of small parts. Since these problems appear in a similar way in nearly all parts of a UAV structure, a calculation using equations based on statistics for larger structures is no longer applicable. In order to accomplish a reasonable preliminary design of small UAV systems, the possibility of a preliminary design method by using a complete parameterization will be presented. Parameterization, in this case, means the computation and respective sizing of all system components with some key values and a number of model-changing parameters. Numerous structural elements as well as a large number of subsystems (e.g., starter and alternator-systems, reduction gear, retractable undercarriage, recovery system, etc.) were built as parametric models. The level of detail is set to a very high value, in fact down to the smallest shim, in order to take into account all unscale effects. These complex models were analyzed by a systematic variation of different parameters to get simplified mass-estimation equations which are now available for the mass prediction of small UAVs, including the effect of integrating different subsystems.},

keywords = {33. Unmanned Vehicles, 34. Advanced Design},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3418,

title = {3418. Virtual Engineering Models for Aircraft Structure Weight Estimation},

author = {Kim Oltmann},

url = {https://www.sawe.org/product/paper-3418},

year  = {2007},

date = {2007-05-01},

booktitle = {66th Annual Conference, Madrid, Spain},

pages = {15},

publisher = {Society of Allied Weight Engineers},

address = {Madrid, Spain},

organization = {Society of Allied Weight Engineers},

abstract = {This paper describes an engineering model to enable a multidisciplinary design team to address a wider range of complex design issues much earlier than is common today. The virtual engineering model is dedicated to simulate arbitrary structural layouts that incorporate the finite element method into preliminary aircraft design. Moreover, it provides a more accurate geometrical representation of the entire aircraft, both outer surfaces and structural topology, early in the design process. This aircraft modeling will enable interdisciplinary teams to involve more structural and manufacturing requirements so that their effect on weight and cost is known much earlier, gathering higher design fidelity. The goal has been to develop modeling methods using the parametric-associative approach that will take into account designer inputs throughout agreed parameter interfaces; and it does not require extensive modeling effort several times. To test the herein presented model in an enterprise environment, different use cases on component and assembly level were conducted while satisfying typical aircraft design requirements from a configuration and a structural point of view. The results further indicate that the virtual engineering model could provide decisive advantage in terms of time required to find an appropriate component design, a reliable common data source distributed to all incorporated disciplines, and design fidelity. It also indicates that the much earlier involvement of virtual engineering models in a conceptual design process provides major interdisciplinary interfaces so that all design information are obviously shared by avoiding risk that might appear when several data transformations have to be executed.},

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

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3409,

title = {3409. Landing Gear Mass Prediction. A Combined Analytic and Parametric Approach},

author = {Adrian Harrison and Sidney Smith and Edward Kay and Evangelos Vekris},

url = {https://www.sawe.org/product/paper-3409},

year  = {2007},

date = {2007-05-01},

booktitle = {66th Annual Conference, Madrid, Spain},

pages = {20},

publisher = {Society of Allied Weight Engineers},

address = {Madrid, Spain},

organization = {Society of Allied Weight Engineers},

abstract = {Current parametric methods for landing gear mass prediction are based on relationships derived from existing aircraft and landing gear mass data. They can provide good results using minimal input and effort, although the resulting mass predictions are inherently linked to the design assumptions of legacy aircraft. Also, the methods cannot be used to perform trade studies that would be useful at early stages of the aircraft design process (e.g., landing gear mass vs. shock-absorber stroke, or vs. material choice). Analytic methods attempt to approximate the landing gear design process by calculating loads to size initial structural concepts. They require more detailed data than parametric methods and simplified structures are assumed that can exclude some important details. Also, it is difficult to predict robust values of overall gear weight from an idealized structural weight synthesized by this process. However, analytic methods can be used to perform early trade studies. This paper reviews the progress towards a combined analytic and parametric method that employs the benefits of both approaches. The analysis process starts from a set of data that would typically be available at early stages of the design process and uses an iterative sequence that aims to provide reliable predictions of landing gear mass. The method attempts to simulate the landing gear design process in enough detail to provide an early concept phase mass prediction.},

keywords = {22. Weight Engineering - Structural Design, 23. Weight Engineering - Structural Estimation},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3303,

title = {3303. Evolutionary Feature Based Weight Prediction},

author = {Anna Baker and Douglas Smith},

url = {https://www.sawe.org/product/paper-3303},

year  = {2003},

date = {2003-05-01},

booktitle = {62nd Annual Conference, New Haven, Connecticut},

pages = {23},

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

address = {New Haven, Connecticut},

abstract = {Many weight prediction methods operate ?analytically,? deriving an ideal structural weight, and then accounting for non-optimum structural penalties using a factoring approach. 

This paper presents an alternative weight prediction philosophy that combines elements of traditional mass accounting with estimated sizing data to produce detailed and accurate weights; the component weight is calculated from a set of detailed parameters using a simplified traditional accounting method. These detailed parameters describe the predicted design of the particular component in its entirety, identifying and sizing all features. 

The large number of detailed parameters required would normally preclude the use of this method during the early project phases ? where weight prediction is most valuable. However, these detailed parameters can be obtained using their respective driving parameters. A generative design approach allows the prediction of relevant features. Using parametric relationships based upon initial load estimates enables the prediction of detailed sizing. 

The result is a versatile method which can be implemented at any stage of a project to generate predicted weights. The resulting weights contain correct causality for ideal structural weight and simultaneously integrate weight resulting from manufacturing constraints and other design considerations. 

Other benefits of this method include being able to identify the true weight drivers of a component and ascertain the weight impact of particular design alterations and manufacturing methods.},

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

pubstate = {published},

tppubtype = {inproceedings}

}