SAWE Technical Papers

@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{3741,

title = {3741. Finding the Balance Between Accuracy and Practicality in Deadweight Survey},

author = {Colin MacFarlane and Manuela Bucci},

url = {https://www.sawe.org/product/paper-3741},

year  = {2020},

date = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {24},

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

address = {Virtual Conference},

abstract = {Deadweight audits are exercises required to calculate the vessel lightweight by deduction from the actual ship weight. Depending on the size of the vessel, they can take a few hours to several days. Minimising the duration of the exercise should be prioritised since accuracy of the result is connected to avoidance of changes in the recorded vessel's configuration during the audit. This leads to a compromise between precision and the accuracy that can be achieved: estimating the weight of the deadweight based on experience is the quickest method, weighing everything with calibrated scales is the most precise. An intermediate solution is to find the deadweight partly with estimates, partly with weighing.Experience with all three of these methods showed that accuracy can be achieved even if relatively poor resolution is accepted, if some precautions are taken when recording the weights.This paper presents three study cases and the calculation of uncertainty in the deadweight that derived from the different approaches. The uncertainty and the time spent to complete the audit are used to define an efficiency estimator to rate the deadweight audit.The conclusion is a method to upgrade data recording that allows production of a more meaningful result.},

keywords = {08. Weighing, 13. Weight Engineering - Marine, 21. Weight Engineering - Statistical Studies, 35. Weight Engineering - Offshore},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3743,

title = {3743. FVA30: Application of Probabilistic Mass Estimation Methods to the Design of a Touring Motor Glider},

author = {M. Konersmann and M. Schmidt and S. Neveling and M. Scholjegerdes and F. Diekmann and T. Moxter and Miguel Nuño},

url = {https://www.sawe.org/product/paper-3743},

year  = {2020},

date = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {16},

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

address = {Virtual Conference},

abstract = {In early design phases the mass and position of many aircraft components is uncertain. So, it is not possible to accurately calculate key aircraft parameters such as the total mass and center of gravity. A possible approach to deal with these uncertainties is using pessimistic and optimistic estimations for every component. This approach considers only the boundary values and can therefore lead to very conservative decisions. To reduce the uncertainty of the calculations and get a better estimation of the expected mass properties probabilistic mass estimation methods can be used.The FVA 30 is a hybrid electric motorglider being developed by students at the Flugwissenschaftliche Vereinigung Aachen (FVA). The configuration of the prototype features two electric engines in the V-tail unit and is therefore especially sensitive to mass changes. In this paper the usage of probabilistic mass estimation and propagation methods to design the FVA 30 is presented. Several methods to estimate probability distributions of different components are described. The propagation of uncertainties is calculated using Monte Carlo simulations with random sampling. At last, the probabilistic calculation results are discussed and compared with the ones using a deterministic method.},

keywords = {11. Weight Engineering - Aircraft Estimation, 21. Weight Engineering - Statistical Studies, Student Papers},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3749,

title = {3749. One Fits All? A Comparison of Weight Estimation Methods for Preliminary Aircraft Design},

author = {Arthur Kluender and Andreas Gobbin},

url = {https://www.sawe.org/product/paper-3749},

year  = {2020},

date = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {17},

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

address = {Virtual Conference},

abstract = {Is there any compelling way to precisely determine the major masses of an aircraft in preliminary design stages? If so, do the results match the real airplane weight properties, when it is built? This paper presents a comprehensive overview of commonly used approaches, highlighting their individual (dis)advantages and eligibility for typical transport missions. The study evaluates widely used, of-the-book-methods for weight estimation and searches for the most accurate approach among them. Each method is applied to determine the masses of four different aircraft, each of them representing a typical aircraft category. The results are put in relation to the real masses, extracted from the corresponding manufacturers manual. In addition, an extended and modified method, already existing and being used at the Department for Aircraft Design and Lightweight Structures at the Technical University of Berlin, is included in the study and tested for its reliability. The overall objective of this paper is to evaluate, whether there is a method that precisely calculates all relevant masses or else, which one delivers the most accurate results for various aircraft types. In order to differentiate even further, the set of required input parameters is considered. In early design phases, typically only a few of those are known. Hence, a method that leads to accurate results with minimal input is favorable for preliminary design. The study indicates that none of the methods covers all the aircraft types. However, tendencies show that some approaches suit certain aircraft types better than others. Most of them provide satisfactory results for an average, jet-engine propelled, single aisle, medium range aircraft in conventional twinjet configuration. Regarding more unusual configurations, for example with turboprop engines, the outcome differs noticeably. Also, for long range aircraft, only a few methods produce realistic numbers. According to this exploration, guidelines on when to use which method are provided. This is followed by an outlook, giving recommendations on the development of new methods. Ultimately, a suggestion on how to consider new technologies and implement them into existing methods of weight estimation is given.},

keywords = {11. Weight Engineering - Aircraft Estimation, 21. Weight Engineering - Statistical Studies, Student Papers},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3710,

title = {3710. Application of the Law of Propagation of Uncertainties to a Weight and CG},

author = {Anjie Emmett},

url = {https://www.sawe.org/product/paper-3710},

year  = {2019},

date = {2019-05-01},

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

pages = {49},

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

address = {Norfolk, Virginia},

abstract = {In order to quantify potential errors in a measurement system, the uncertainties of all measurement sources must be combined to generate a total system uncertainty. This quantified measurement system uncertainty may be used as a decision-making tool to determine the required accuracy of measurement devices such as load cells, scales, and laser trackers.For NASA's Ascent Abort 2 (AA-2) Flight Test, such an uncertainty quantification was performed to ensure that the Ground Support Equipment (GSE) designed to measure the mass and center of gravity (CG) of a Crew Module (CM) would meet the accuracy requirements set forth by the program. The uncertainties of the load cells used were combined with the laser tracker system's positional uncertainty to determine the overall measurement system uncertainty, which met program requirements.},

keywords = {15. Weight Engineering - Missile 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{3717,

title = {3717. Evaluating a CoG Envelope Using a Probabilistic Approach},

author = {Robert J. Hundl},

url = {https://www.sawe.org/product/paper-3717},

year  = {2019},

date = {2019-05-01},

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

pages = {15},

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

address = {Norfolk, Virginia},

abstract = {In the Energy and Chemicals Construction Industry, many onshore projects are using modular construction. This type of construction requires that the modules be transported from the fabrication yard to the project site. The fabrication yard may be distant from the project site, thus requiring a combination of ocean transportation and land transportation. To verify the design, the structural analysis uses a given design weight limit and center of gravity (CoG) envelope for the various modes of transportation. The size of the CoG envelope can influence the strengthening requirements for the structure during the transportation phases. CoG envelopes are typically set as a percentage of the module length and width. In special cases, a probabilistic approach could be used to reduce the typical CoG envelope size for reducing the amount of strengthening requirements while also quantifying the risk to the project for reducing the size of the CoG envelope.},

keywords = {13. Weight Engineering - Marine, 21. Weight Engineering - Statistical Studies, 35. Weight Engineering - Offshore},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3718,

title = {3718. Center of Buoyancy and Center of Gravity Measurement of a Submersible Vehicle},

author = {James Blair},

url = {https://www.sawe.org/product/paper-3718},

year  = {2019},

date = {2019-05-01},

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

pages = {16},

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

address = {Norfolk, Virginia},

abstract = {Stability of submersible vehicles is dependent on the relationship between the center of gravity and center of buoyancy locations on the object. Improper relationships between the two can reduce performance and adversely affect the mission goals of the vehicle. Measuring these values can reveal variations from the designed values that may have been introduced during the manufacturing or assembly process. These values can also change in modular submersible vehicles which allow swapping or modifying components based on the needs of their mission. Errors associated with an improper relationship may not arise until sea testing, which may lead to the need for vehicle disassembly in order to shift or change ballast weights of the submersible.This paper examines a measurement system designed to measure the center of gravity and the center of buoyancy of a submersible object using a hanging weight and center of gravity instrument. The method demonstrated is applicable for vehicles ranging from a few pounds to upwards of 15 tons. With proper fixturing, the machine is capable of measuring center of buoyancy and center of gravity in all 3 axes, which can help determine lateral, longitudinal, and directional stability of a part. This paper outlines a process for measuring submersible vehicles (with negative or slightly positive buoyancy) to determine weight, buoyant force, center of gravity, and center of buoyancy.},

keywords = {13. Weight Engineering - Marine, 21. Weight Engineering - Statistical Studies},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3719,

title = {3719. Modernising Ship Stability: Lightship Evolution Diagnostics with In-Service Stability},

author = {Manuela Bucci and Colin MacFarlane},

url = {https://www.sawe.org/product/paper-3719},

year  = {2019},

date = {2019-05-01},

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

pages = {24},

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

address = {Norfolk, Virginia},

abstract = {Lightship mass and center of gravity are the basis for assessing ship regulatory stability and the maximum payload that the ship can load results from this assessment. Knowing the ship mass and centre of gravity is therefore of utmost importance for both commercial and safety reasons.It is known that, over time, both these quantity change. At present, changes in the lightship are addressed by five-yearly audits that may lead to an inclining experiment - the traditional way to measure ship mass and centre of gravity. The time gaps are filled with estimates based on weight control which can be shown to be a 'random walk' process. This means that, temporarily, undetected worsening of the ship stability might occur.Draught measurement provides immediate feedback of the accuracy of the estimate of weight change, provided draught sensors are adequately maintained. Evidence of change in the vertical position of the lightship center of gravity is not, however, obvious.In-service stability measurements, integrated into the vessel's operational routine, directly estimate the vessel VCG and can diagnose changes in the lightship vertical moment using statistical process control techniques. Changes in the progression of mean values of Deadweight and Lightship vertical moment are used instead of records of weight changes to build a model of ship stability over time with uncertainty on the mean value decreasing with increasing number of measurements. Weight control remains important to characterize the changes and discrepancies from the loading program can be used to identify sensor failures, defective estimates of cargo deadweight and Lightship changes.This paper briefly reviews conventional techniques (referring to previous Conference papers). It then discusses attempts to perform conventional inclinings at sea and the difficulties in obtaining precision, before setting out the methods of in-service stability assessment, techniques for analysis of the results and finally the control limits that can be used to trigger further investigation. The technology is suitable for autonomous vessels.},

keywords = {13. Weight Engineering - Marine, 21. Weight Engineering - Statistical Studies},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3720,

title = {3720. A Practical and Proactive Way of Managing Weight & Center of Gravity Uncertainty Using the Successive Principle},

author = {Runar Aasen},

url = {https://www.sawe.org/product/paper-3720},

year  = {2019},

date = {2019-05-01},

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

pages = {18},

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

address = {Norfolk, Virginia},

abstract = {One of the challenges in mass properties is how to handle the uncertainty in an early stage estimate of weight and center of gravity (CG) and its impact throughout the life of the project. Risk is sometimes defined as the product of consequence multiplied by uncertainty, and for many shipbuilding projects the consequence of missing the mark on either the weight or CG can be dramatic. That makes reducing uncertainty essential to avoiding a high-risk project.Dr. Steen Lichtenberg started as early as the 1970's to develop a method for proactive management of uncertainty using the successive principle. The method is a practical way to manage opportunities and risk. The underlying philosophy states that realism in forecasts requires a qualitative phase as well as a quantitative phase. In the qualitative phase, an analysis group of people should be established, while the quantitative phase should establish a basic structure of main items, followed by a systematic detailing process and an action plan.While the method typically handles uncertainties related to the economics of large projects, this paper will look at how the principles and processes involved can be applied to the weight and CG challenges during ship design and construction. A general introduction to the successive principle will be given, the basic applications will be presented, and discussions and examples of use cases will be included. The goal is to add another tool to the toolbox of the weight engineer to help secure successful projects.},

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

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{3699,

title = {3699. The Health of Mass Properties Engineering in Aerospace, Marine, Offshore, Land Vehicles and Allied Industries - Results of a 2018 Industry Survey},

author = {Clint Stephenson and William Boze},

url = {https://www.sawe.org/product/paper-3699},

year  = {2018},

date = {2018-05-01},

booktitle = {77th Annual Conference, Irving, Texas},

pages = {81},

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

address = {Irving, Texas},

abstract = {At the 76th International Society of Allied Weight Engineers (SAWE) conference in Montreal, Canada, the president-elect of the society gave a presentation entitled 'The Mass Properties Discipline - Risk and Opportunity'. This presentation provided a perception of the health of the mass properties discipline based on limited published material, most of it over a decade old. In order to substantiate or disprove the conjecture made in that 2017 presentation, the authors devised and conducted a mass properties engineering industry survey in 2018, the results of which are presented in this paper. Similar to the aforementioned presentation, the ultimate objective of this effort is to stimulate increased collaboration between Academia, SAWE Company Members and Corporate Partners, society members, and the SAWE Executive Board towards a common objective in addressing the current risk and opportunities.},

keywords = {16. Weight Engineering - Organization, 21. Weight Engineering - Statistical Studies},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3701,

title = {3701. Mass Properties in Support of Class Analysis (a.k.a. MP End of Days)},

author = {Ricardo Roy},

url = {https://www.sawe.org/product/paper-3701},

year  = {2018},

date = {2018-05-01},

booktitle = {77th Annual Conference, Irving, Texas},

pages = {18},

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

address = {Irving, Texas},

abstract = {You receive the following Program Office Request: In lieu of mission specific analysis, it is dictated to you that Class Analysis be instituted to lower overall program cost. There may be other methods to address this request but this paper addresses one process that provided mass properties in support of program 'Class Analysis'. To get started, a definition of Class Analysis is prudent. Class Analysis is any single study that incorporates all conceived configurations of a vehicle from mass properties (MP) perspective and the MP uncertainties associated with them.The main purpose is to provide a range of mass properties with a high likelihood that the current and future fleet elements will not exceed them.This process is based on simulated aerospace hardware data and does not reflect any specific line of vehicles. Additionally, the same process may be applied to non-aerospace production programs. All that is required is a good history of launch vehicle segments along with mass properties and uncertainties for each segment. Ten (10) years of history is ideal, but a smaller term is acceptable knowing that risk may be incurred. A segment is defined as any portion of the launch vehicle that may get jettisoned during the launch cycle. A robust verification process to validate that the assumed variables are still compliant is also a must.This analysis will not only be performed by the mass properties group but also by all the downstream users (Guidance, Flight Mechanics, Separation, Structures, Ground Ops ...etc.). Mass Properties is the initial cog in a long string of analysis that will be scrutinized. This being said, the mass properties group must not operate in a vacuum, but coordinate with these downstream users to access the effects of your assumptions. All data units herein will be presented as: Mass (M) = pounds-mass (lbm); Center of Mass (CM) = inches (in) or stations; and Moment and Product of Inertias (MOI and POI) = slug-foot2 (sl-ft2). Inertias will be in respect to the CM. A positive integral definition will be used for POI.},

keywords = {15. Weight Engineering - Missile Estimation, 19. Weight Engineering - Spacecraft Estimation, 21. Weight Engineering - Statistical Studies},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3675,

title = {3675. Weight Management During Engineering Development - 2016 Sawe Survey Results},

author = {Doug Fisher},

url = {https://www.sawe.org/product/paper-3675},

year  = {2017},

date = {2017-05-01},

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

pages = {28},

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

address = {Montreal, Canada},

abstract = {This is the report of a survey on product weight management during engineering development. The objective is to understand the size, organization and influence of weight engineering teams on a product's engineering development. The survey was given to members of SAWE (the International Society of Allied Weight Engineers) in the aircraft, spacecraft, marine and land vehicle industries during the 2016 international conference. Data was gathered on:* Weight engineering staff size, experience and documented work instructions* Engineering team reporting structure and responsibility for product weight* Weight goals and weight reduction activities during product development and their impact on the project* The weight engineering focals' influence on the product design35 responses were received, representing the full range of targeted industries, with most respondents from the aircraft and marine industries. Small (fewer than 100 engineers), medium (100 to 500) and large organizations (more than 500 engineers) are represented.Limited by such a small data set, analysis focused on broad trends and relationships. Common themes are small, aging weight engineering staffs and poor documentation of work instructions, which could hinder knowledge transfer to the next generation. The person the weight engineers report to may not be responsible for meeting the development project weight goal, possibly diluting 'ownership' of the weight. Most respondents accept a weight challenge in their projects which may require weight reduction activity to achieve, even when they don't have a complete understanding of weight risks. Despite challenging weight goals and weight reduction activities, most respondents indicate the weight engineer has little or no influence on the product design.},

keywords = {16. Weight Engineering - Organization, 21. Weight Engineering - Statistical Studies},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3686,

title = {3686. Statistical Mass Properties Predictions for a Production Program},

author = {Ricardo Roy},

url = {https://www.sawe.org/product/paper-3686},

year  = {2017},

date = {2017-05-01},

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

pages = {12},

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

address = {Montreal, Canada},

abstract = {This paper provides a process/methodology for predicting mass properties for a production program. The ANSA/AAIA S-120A Standard (Reference $#$1) is highly recommended for developmental articles and may be too conservative for production programs. The S-120A Standard addresses mass predictions using growth as primary criteria for predicting mass. This paper eliminates growth which uses the Growth Depletion Schedules (see Table 1 for an example), and introduces mass bias (MB) which is based on the statistical differences between the predicted mass and its final Tested and Guaranteed (TAG) values over a history of vehicles.This paper is based on aerospace experiences; however, it is generic enough where it can be applied to any non-aerospace hardware line. Where any multiple lift point process is used to verify Center of Mass (CM), the Center of Mass Bias (CMB) may also be calculated and is addressed herein. This process/methodology may also be applied to Moments and Products of Inertia if a verification process is in place to quantify them.To implement this process/methodology, all that is required is a robust verification plan and a database that is current. All data will be presented in pound-mass.},

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

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3688,

title = {3688. Uncertainty Analysis Applied to Two Historic Inclining Experiments},

author = {David Hansch},

url = {https://www.sawe.org/product/paper-3688},

year  = {2017},

date = {2017-05-01},

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

pages = {55},

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

address = {Montreal, Canada},

abstract = {Uncertainty analyses were performed on the inclining experiments of two historic passenger liners to determine the drivers of the lightship weight and KG uncertainty. These analyses were further used to determine potential areas to improve the experimental uncertainty as well as areas of the test that can be relaxed without significantly reducing the certainty of the test results. The largest driver in the uncertainty of lightship KG was found to be the uncertainty in displacement as inclined. It is recommended that whenever possible a wedges method of displacement correction be employed to minimize the uncertainty of the test. The wedges method based on actual keel deflection is ideal, but even the parabolic wedges method offers a significant advantage over the 3/4 hog or sag correction method.},

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

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3693,

title = {3693. A Random Method for Picking Module Stowage Solutions for Barges},

author = {Robert Hundl},

url = {https://www.sawe.org/product/paper-3693},

year  = {2017},

date = {2017-05-01},

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

pages = {15},

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

address = {Montreal, Canada},

abstract = {In the Oil & Gas Construction Industry, many onshore projects are using modular construction. This type of construction requires that the modules be transported from the fabrication yard to the project site. The fabrication yard may be distant from the project site, thus requiring ocean transportation. Modules can come in many different sizes, shapes, and weights. Some very large modules require a dedicated barge. However, frequently multiple modules can be placed upon a single barge. Determining module groups for barges can be difficult and time consuming. Figure 1 shows several different types of modules on barges.Determining the type of barge to use, the number needed, and the length of service time can be a daunting logistical task. Costs involved with securing barges and engineering services from barge companies are in the millions of dollars. To complicate matters, barges typically require long lead times. Determining what type of barge or the appropriate 'mix' of barges to use can help reduce the cost of the project.This paper will demonstrate a method to easily solve for a group solution through the use of a random number generator and grading the resultant solutions. This method can easily be applied to other types of problems and industries when it is necessary to pick groups to solve the problem.},

keywords = {13. Weight Engineering - Marine, 21. Weight Engineering - Statistical Studies, 35. Weight Engineering - Offshore},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3570,

title = {3570. Center of Mass Uncertainty Coordinate Transformation},

author = {J H Nakai and Wen Tsai},

url = {https://www.sawe.org/product/paper-3570},

year  = {2012},

date = {2012-05-01},

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

pages = {73},

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

address = {Bad Gögging, Germany},

abstract = {The center of mass (CM) is the mean location of all the system mass, and is typically expressed as a vector in a selected coordinate system. When combining CM data defined in multiple coordinate systems, coordinate transformations are performed using well-known vector transformation algorithms to bring data into a common coordinate system for summation or comparison. CM uncertainties (also known as dispersions) are typically expressed as a set of plus (+) and minus (-) values around the nominal value. CM uncertainties may be visualized as a volume of possible CM locations surrounding the mean value. Uncertainty coordinate transformation is not a well-defined process because it involves transforming boundaries of a volumetric region without a defined shape. There is currently no standard, well-documented method for transforming the coordinates of CM uncertainties. This situation has resulted in CM uncertainty data being handled inconsistently and incorrectly when coordinate transformations are applied. This paper proposes methods and algorithms for performing coordinate transformations on CM uncertainty data, and describes the pros and cons of the various approaches.},

keywords = {03. Center Of Gravity, 21. Weight Engineering - Statistical Studies},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3493,

title = {3493. An Expanded Study of SAWE Paper 3468 - Quantifying Uncertainty and Risk in Vehicle Mass Properties Throughout the Design Development Phase},

author = {William Boze and Elizabeth Heaney},

url = {https://www.sawe.org/product/paper-3493},

year  = {2010},

date = {2010-05-01},

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

pages = {10},

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

address = {Virginia Beach, Virginia},

abstract = {SAWE Paper No. 3468 (Boze & Hester, 2009) demonstrated 

that uncertainty and risk can be quantified by coupling a 

Monte Carlo simulation using Microsoft Excel, mass 

properties data, a work breakdown structure, uncertainty 

categories, and derived probability distributions. The risk can 

be assessed by evaluating the probability of occurrence, the 

standard deviation, and the coefficient of variation resulting 

from randomly varying the mass properties variable within an 

uncertainty category's probability distribution. 

The original paper demonstrated this approach using data 

collected over an 18 month period on an existing ship 

acquisition program. The purpose of this paper is to broaden 

the range of mass properties data used in the same simulation 

model to a five year design acquisition life cycle in order to 

gain increased insight into the use of this method. New 

observations will be drawn as to the required number of 

simulation runs, the various measures of risk, affects on risk of 

physical platform changes to satisfy performance requirement 

changes, as well as disclosing improved graphic methods for 

displaying some risk data.},

keywords = {17. Weight Engineering - Procedures, 21. Weight Engineering - Statistical Studies, 24. Weight Engineering - System Design},

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 = {13. Weight Engineering - Marine, 21. Weight Engineering - Statistical Studies},

pubstate = {published},

tppubtype = {inproceedings}

}