%0 Conference Paper %B 2020 SAWE Tech Fair %D 2020 %T 3739. Rotorcraft Mass Assessment in an Integrated Design Framework %A Schwinn, Dominik B. %A Peter Weiand %K 10. Weight Engineering - Aircraft Design %K 21. Weight Engineering - Statistical Studies %K 24. Weight Engineering - System Design %X

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.

 

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%2 15 %3 20 %4 SAWE3730 %0 Conference Paper %B 2020 SAWE Tech Fair %D 2020 %T 3741. Finding the Balance Between Accuracy and Practicality in Deadweight Survey %A MacFarlane, Colin %A Bucci, Manuela %K 08. Weighing %K 13. Weight Engineering - Marine %K 21. Weight Engineering - Statistical Studies %K 35. Weight Engineering - Offshore %X

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.

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%2 15 %3 20 %4 SAWE3730 %0 Conference Paper %B 2020 SAWE Tech Fair %D 2020 %T 3743. FVA30: Application of Probabilistic Mass Estimation Methods to the Design of a Touring Motor Glider %A M. Konersmann %A M. Schmidt %A S. Neveling %A M. Scholjegerdes %A F. Diekmann %A T. Moxter %A Miguel Nuño %K 11. Weight Engineering - Aircraft Estimation %K 21. Weight Engineering - Statistical Studies %K Student Papers %X

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.

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%2 15 %3 20 %4 SAWE3730 %0 Conference Paper %B 2020 SAWE Tech Fair %D 2020 %T 3749. One Fits All? A Comparison of Weight Estimation Methods for Preliminary Aircraft Design %A Arthur Kluender %A Andreas Gobbin %K 11. Weight Engineering - Aircraft Estimation %K 21. Weight Engineering - Statistical Studies %K Student Papers %X

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.

 

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%2 15 %3 20 %4 SAWE3730 %0 Conference Paper %B 78th Annual Conference, Norfolk, VA %D 2019 %T 3710. Application of the Law of Propagation of Uncertainties to a Weight and CG %A Emmett, Anjie %K 15. Weight Engineering - Missile Estimation %K 21. Weight Engineering - Statistical Studies %X

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.

%B 78th Annual Conference, Norfolk, VA %I Society of Allied Weight Engineers, Inc. %C Norfolk, Virginia %P 49 %8 05/2019 %U https://www.sawe.org/papers/3710/buy %L 15, 21 %1 Non-Member Price: $20.00; Member Price: $15.00 %2 15 %3 20 %4 SAWE3710 %0 Conference Paper %B 78th Annual Conference, Norfolk, VA %D 2019 %T 3716. A Methodology of Determining Parametric Equations from Data with a Worked Example %A Hansch, David Laurence %K 21. Weight Engineering - Statistical Studies %X

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.

%B 78th Annual Conference, Norfolk, VA %I Society of Allied Weight Engineers, Inc. %C Norfolk, Virginia %P 25 %8 05/2019 %U https://www.sawe.org/papers/3716/buy %L 21 %1 Non-Member Price: $20.00; Member Price: $15.00 %2 15 %3 20 %4 SAWE3716 %0 Conference Paper %B 78th Annual Conference, Norfolk, VA %D 2019 %T 3717. Evaluating a CoG Envelope Using a Probabilistic Approach %A Hundl, Robert J. %K 13. Weight Engineering - Marine %K 21. Weight Engineering - Statistical Studies %K 35. Weight Engineering - Offshore %X

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.

%B 78th Annual Conference, Norfolk, VA %I Society of Allied Weight Engineers, Inc. %C Norfolk, Virginia %P 15 %8 05/2019 %U https://www.sawe.org/papers/3717/buy %L 13, 21, 35 %1 Non-Member Price: $20.00; Member Price: $15.00 %2 15 %3 20 %4 SAWE3717 %0 Conference Paper %B 78th Annual Conference, Norfolk, VA %D 2019 %T 3718. Center of Buoyancy and Center of Gravity Measurement of a Submersible Vehicle %A Blair, James %K 13. Weight Engineering - Marine %K 21. Weight Engineering - Statistical Studies %X

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.

%B 78th Annual Conference, Norfolk, VA %I Society of Allied Weight Engineers, Inc. %C Norfolk, Virginia %P 16 %8 05/2019 %U https://www.sawe.org/papers/3718/buy %9 13. Weight Engineering - Marine ; 21. Weight Engineering - Statistical Studies %L 13, 21 %1 Non-Member Price: $20.00; Member Price: $15.00 %2 15 %3 20 %4 SAWE3718 %0 Conference Paper %B 78th Annual Conference, Norfolk, VA %D 2019 %T 3719. Modernising Ship Stability: Lightship Evolution Diagnostics with In-Service Stability %A Bucci, Manuela %A MacFarlane, Colin %K 13. Weight Engineering - Marine %K 21. Weight Engineering - Statistical Studies %X

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.

%B 78th Annual Conference, Norfolk, VA %I Society of Allied Weight Engineers, Inc. %C Norfolk, Virginia %P 24 %8 05/2019 %U https://www.sawe.org/papers/3719/buy %L 13, 21 %1 Non-Member Price: $20.00; Member Price: $15.00 %2 15 %3 20 %4 SAWE3719 %0 Conference Paper %B 78th Annual Conference, Norfolk, VA %D 2019 %T 3720. A Practical and Proactive Way of Managing Weight & Center of Gravity Uncertainty Using the Successive Principle %A Aasen, Runar %K 21. Weight Engineering - Statistical Studies %X

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.

%B 78th Annual Conference, Norfolk, VA %I Society of Allied Weight Engineers, Inc. %C Norfolk, Virginia %P 18 %8 05/2019 %U https://www.sawe.org/papers/3720/buy %L 21 %1 Non-Member Price: $20.00; Member Price: $15.00 %2 15 %3 20 %4 SAWE3720 %0 Conference Paper %B 78th Annual Conference, Norfolk, VA %D 2019 %T 3729. Application of SAWE Course “Developing Basic Parametric Methods” to Nacelle Weight Estimating %A Fisher, Doug %K 10. Weight Engineering - Aircraft Design %K 11. Weight Engineering - Aircraft Estimation %K 21. Weight Engineering - Statistical Studies %X

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.

%B 78th Annual Conference, Norfolk, VA %I Society of Allied Weight Engineers, Inc. %C Norfolk, Virginia %P 17 %8 05/2019 %U https://www.sawe.org/papers/3729/buy %L 10, 11, 21 %1 Non-Member Price: $20.00; Member Price: $15.00 %2 15 %3 20 %4 SAWE3729 %0 Conference Paper %B 77th Annual Conference, Irving, Texas %D 2018 %T 3699. The Health of Mass Properties Engineering in Aerospace, Marine, Offshore, Land Vehicles and Allied Industries – Results of a 2018 Industry Survey %A Stephenson, Clint %A Boze, William %K 16. Weight Engineering - Organization %K 21. Weight Engineering - Statistical Studies %X

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.

%B 77th Annual Conference, Irving, Texas %I Society of Allied Weight Engineers, Inc. %C Irving, Texas %P 81 %8 05/2018 %U https://www.sawe.org/papers/3699/buy %1 Non-Member Price: $20.00; Member Price: $15.00 Members: First 10 product downloads are Free. %2 15 %3 20 %4 SAWE3699 %0 Conference Paper %B 77th Annual Conference, Irving, Texas %D 2018 %T 3701. Mass Properties in Support of Class Analysis (a.k.a. MP End of Days) %A Roy, Ricardo %K 15. Weight Engineering - Missile Estimation %K 19. Weight Engineering - Spacecraft Estimation %K 21. Weight Engineering - Statistical Studies %X

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.

%B 77th Annual Conference, Irving, Texas %I Society of Allied Weight Engineers, Inc. %C Irving, Texas %P 18 %8 05/2018 %U https://www.sawe.org/papers/3701/buy %1 Non-Member Price: $20.00; Member Price: $15.00 Members: First 10 product downloads are Free. %2 15 %3 20 %4 SAWE3701 %0 Conference Paper %B 76th Annual Conference, Montreal, Canada %D 2017 %T 3675. Weight Management During Engineering Development - 2016 Sawe Survey Results %A Fisher, Doug %K 16. Weight Engineering - Organization %K 21. Weight Engineering - Statistical Studies %X

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 design

35 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.

%B 76th Annual Conference, Montreal, Canada %I Society of Allied Weight Engineers, Inc. %C Montreal, Canada %P 28 %8 05/2017 %U https://www.sawe.org/papers/3675/buy %1 Non-Member Price: $20.00; Member Price: $15.00 Members: First 10 product downloads are Free. %2 15 %3 20 %4 SAWE3675 %0 Conference Paper %B 76th Annual Conference, Montreal, Canada %D 2017 %T 3686. Statistical Mass Properties Predictions for a Production Program %A Roy, Ricardo %K 21. Weight Engineering - Statistical Studies %X

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.

%B 76th Annual Conference, Montreal, Canada %I Society of Allied Weight Engineers, Inc. %C Montreal, Canada %P 12 %8 05/2017 %U https://www.sawe.org/papers/3686/buy %1 Non-Member Price: $20.00; Member Price: $15.00 Members: First 10 product downloads are Free. %2 15 %3 20 %4 SAWE3686 %0 Conference Paper %B 76th Annual Conference, Montreal, Canada %D 2017 %T 3688. Uncertainty Analysis Applied to Two Historic Inclining Experiments %A Hansch, David %K 21. Weight Engineering - Statistical Studies %X

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.

%B 76th Annual Conference, Montreal, Canada %I Society of Allied Weight Engineers, Inc. %C Montreal, Canada %P 55 %8 05/2017 %U https://www.sawe.org/papers/3688/buy %1 Non-Member Price: $27.50; Member Price: $20.62 Members: First 10 product downloads are Free. %2 20.62 %3 27.5 %4 SAWE3688 %0 Conference Paper %B 76th Annual Conference, Montreal, Canada %D 2017 %T 3693. A Random Method for Picking Module Stowage Solutions for Barges %A Robert Hundl %K 13. Weight Engineering - Marine %K 21. Weight Engineering - Statistical Studies %K 35. Weight Engineering - Offshore %X

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.

%B 76th Annual Conference, Montreal, Canada %I Society of Allied Weight Engineers, Inc. %C Montreal, Canada %P 15 %8 05/2017 %U https://www.sawe.org/papers/3693/buy %1 Non-Member Price: $20.00; Member Price: $15.00 Members: First 10 product downloads are Free. %2 15 %3 20 %4 SAWE3693 %0 Conference Paper %B 71st Annual Conference, Bad Gögging, Germany %D 2012 %T 3570. Center of Mass Uncertainty Coordinate Transformation %A Nakai, J H %A Tsai, Wen %K 03. Center Of Gravity %K 21. Weight Engineering - Statistical Studies %X 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. %B 71st Annual Conference, Bad Gögging, Germany %I Society of Allied Weight Engineers, Inc. %C Bad Gögging, Germany %P 73 %8 05/2012 %U https://www.sawe.org/papers/3570/buy %1 Non-Member Price: $36.50; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 36.5 %4 SAWE3570 %0 Conference Paper %B 69th Annual Conference, Virginia Beach, Virginia %D 2010 %T 3493. An Expanded Study of SAWE Paper 3468 - Quantifying Uncertainty and Risk in Vehicle Mass Properties Throughout the Design Development Phase %A Boze, William %A Heaney, Elizabeth %K 17. Weight Engineering - Procedures %K 21. Weight Engineering - Statistical Studies %K 24. Weight Engineering - System Design %X 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. %B 69th Annual Conference, Virginia Beach, Virginia %I Society of Allied Weight Engineers, Inc. %C Virginia Beach, Virginia %P 10 %8 05/2010 %U https://www.sawe.org/papers/3493/buy %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE3493 %0 Conference Paper %B 69th Annual Conference, Virginia Beach, Virginia %D 2010 %T 3505. Early Stage Weight and Cog Estimation Using Parametric Formulas and Regression on Historical Data %A Aasen, Runar %A BJORHOVDE, STEIN %K 13. Weight Engineering - Marine %K 21. Weight Engineering - Statistical Studies %X 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. %B 69th Annual Conference, Virginia Beach, Virginia %I Society of Allied Weight Engineers, Inc. %C Virginia Beach, Virginia %P 35 %8 05/2010 %U https://www.sawe.org/papers/3505/buy %L 3497 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE3505 %0 Conference Paper %B 69th Annual Conference, Virginia Beach, Virginia %D 2010 %T 3511. The Use of Inferential Statistics in Ships’ Stability Analysis %A COOLEY, MELISSA %A DIGGS, MICHAEL %A Hansch, David %K 13. Weight Engineering - Marine %K 21. Weight Engineering - Statistical Studies %X A deterministic approach is traditionally performed for damage stability analysis on Navy ships, while commercial, ABS accredited, ships use Safety of Life At Sea (SOLAS) and International Maritime Organization (IMO) probability studies. SOLAS and IMO analyses provide an attained subdivision index, but do not allow the designer to determine the actual KG value required to survive damage a certain percentage of the time. In a deterministic approach one would have to analyze all cases to determine the passing percentage. The use of inferential statistics will allow one to determine the KG required for a ship to survive damage a certain percentage of time, or the percentage of cases that will meet the analyzed stability criteria at a particular KG, without having to analyze every damage case, and provides more detail than an attained subdivision index, as with SOLAS and IMO requirements. %B 69th Annual Conference, Virginia Beach, Virginia %I Society of Allied Weight Engineers, Inc. %C Virginia Beach, Virginia %P 17 %8 05/2010 %U https://www.sawe.org/papers/3511/buy %L 3497 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE3511 %0 Conference Paper %B 68th Annual Conference, Wichita, Kansas %D 2009 %T 3468. Quantifying Uncertainty and Risk in Vehicle Mass Properties Throughout the Design Development Phase %A Boze, William %A Hester, Patrick %K 21. Weight Engineering - Statistical Studies %K Mike Hackney Best Paper Award %X

In the acquisition of any new vehicle program, whether it be a marine, space, aircraft or ground transportation vehicle, there is the need throughout the life-cycle development phases to periodically assess the level of uncertainty and risk in the estimated or calculated prediction of the delivered vehicle mass properties characteristics (such as weight, center of gravity, or mass moment of inertia). Published industry standards for control of mass properties characteristics identify the components necessary for a desired outcome, yet occasionally there is a vehicle acquisition program which falls short of that desired mark. There can be many causes for this occurrence, and the causes can even appear within a program having a robust mass properties control plan. The focus of this research is on the unpredictability in the uncertainty of the reported values and associated risks, and the application of a hybrid approach to quantify that uncertainty and risk. Using current mass properties control techniques integrated with management science risk analysis approaches, the process is evaluated on an existing vehicle acquisition program covering a span of several years.

%B 68th Annual Conference, Wichita, Kansas %C Wichita, Kansas %P 17 %8 5/16/2009 %U https://www.sawe.org/papers/3468/buy %9 21. Weight Engineering - Statistical Studies %M 3436 %L 21 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE3468 %0 Conference Paper %B 68th Annual Conference, Wichita, Kansas %D 2009 %T 3474. U.S. Fighter Aircraft Design, Weight And Performance Trends %A Dudley M Cate %K 10. Weight Engineering - Aircraft Design %K 21. Weight Engineering - Statistical Studies %X Weight engineers struggle with aircraft weight because it is so critically important to aircraft performance. Nowhere is this truer than for fighter aircraft. The U.S. has been operating fighters since 1917 and designing them since almost that long ago. This paper presents three sets of information for U.S. fighters: the first set consists of quantitative trends versus time for some top-level design, weight and performance parameters for U.S. fighters. The parameters addressed include ones commonly cited in aircraft histories (max speed, combat ceiling, initial climb rate) plus others such as weight empty fraction, fuel fraction, wing loading and power- and thrust-to-weight ratios. The second set of information is the results of searches for correlations between design parameters (e.g., wing loading) and performance parameters (e.g., climb rate). The third set consists of brief descriptions and assessments of the requirements, technologies, design, performance and operational suitability of each of the fifty-odd aircraft in the database. %B 68th Annual Conference, Wichita, Kansas %C Wichita, Kansas %P 95 %8 5/16/2009 %U https://www.sawe.org/papers/3474/buy %9 10. Weight Engineering - Aircraft Design; 11. Weight Engineering - Aircraft Design ; 21. Weight Engineering - Statistical Studies %M 3436 %L 10;11;21 %1 Non-Member Price: $47.50; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 47.5 %4 SAWE3474 %0 Conference Paper %B 68th Annual Conference, Wichita, Kansas %D 2009 %T 3477. The Health of Mass Properties Engineering in the Marine Industries %A Tellet, David %K 13. Weight Engineering - Marine %K 21. Weight Engineering - Statistical Studies %K 30. Miscellaneous %X

A survey on the health of mass properties engineering in the marine field was conducted using the Internet to gather demographic, job satisfaction, industry health, and SAWE specific data. The survey consisted of 20 multiple choice, ranking, and fill-in questions. This paper presents the summary of the data received (139 respondents) for each question and examines some correlations between age, employers, expected attrition, and membership in the SAWE. Selected narrative answers are shown in the body of the paper with all text responses included in the Appendix.

%B 68th Annual Conference, Wichita, Kansas %C Wichita, Kansas %P 58 %8 5/16/2009 %U https://www.sawe.org/papers/3477/buy %9 13. Weight Engineering - Marine ; 21. Weight Engineering - Statistical Studies ; 30. Miscellaneous %M 3436 %L 13 ; 21 ; 30 %1 Non-Member Price: $29.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 29 %4 SAWE3477 %0 Conference Paper %B 68th Annual Conference, Wichita, Kansas %D 2009 %T 3478. Weight Report Sanity Checks using Information Graphics %A Tellet, David %K 13. Weight Engineering - Marine %K 21. Weight Engineering - Statistical Studies %X

This paper presents methods of performing “sanity checks” on weight reports using un-traditional information graphics. The paper discusses using bubble plots and treemaps to look at three digit weights by group and three digit weights by weight maturity levels. Comparisons of pie charts with dotcharts are discussed along with other statistical graphics such as triangle plots, stars plots, and sparklines, all of which can be used to identify potential problem areas and can be used to compare one quarterly weight report with another. The use of animated graphics is briefly discussed with regard to quickly identifying trends.

%B 68th Annual Conference, Wichita, Kansas %C Wichita, Kansas %P 23 %8 5/16/2009 %U https://www.sawe.org/papers/3478/buy %9 13. Weight Engineering - Marine ; 21. Weight Engineering - Statistical Studies %M 3436 %L 13 ; 21 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE3478 %0 Conference Paper %B 67th Annual Conference, Seattle, Washington %D 2008 %T 3455. Submarine Lead and Margin Attrition %A Tellet, David %K 13. Weight Engineering - Marine %K 21. Weight Engineering - Statistical Studies %X

The selection of service life margins for a submarine has a direct impact on the design and on acquisition and operational costs because this margin is carried as actual lead ballast. Past studies carried out by NAVSEA have attempted to use lead attrition and margin lead attrition data from previous submarine classes to determine optimum ranges for service life margin. This paper documents and updates the data used in those studies and examines the data in terms of means, standard deviations, and confidence bounds around linearly fitted models of the data. The differences among the submarine classes is noted and an attempt is made to improve the fitted models by the removal of outliers. Based on the historical data and the analysis in the paper, a recommended range for service life margin for conventional attack submarines is given to be between 2.00% and 3.25% of light ship weight.

%B 67th Annual Conference, Seattle, Washington %C Seattle, Washington %P 26 %8 5/19/2008 %U https://www.sawe.org/papers/3455/buy %9 13. Weight Engineering - Marine; 21. Weight Engineering - Statistical Studies %M 3455 %L 13; 21 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE3455 %0 Conference Paper %B 64th Annual Conference, Annapolis, Maryland %D 2005 %T 3360. Are You Sure? - Uncertainty in Mass Properties Engineering %A Zimmerman, Robert L. %A Nakai %K 12. Weight Engineering - Computer Applications %K 21. Weight Engineering - Statistical Studies %K Mike Hackney Best Paper Award %X

The Mass Property Engineer?s role in the engineering organization is ultimately to report the mass properties of the organization?s vehicle, so that the vehicle?s performance can be characterized. It is insufficient merely to report the mass properties as a discrete entity ? the characterization of performance requires the possible variations of the vehicle?s mass properties also be determined and reported by the Mass Property Engineer to the team. Mass Property Engineers have an expectation, based on precision computerized drafting and manufacturing equipment, electronic mass property tallying, and high accuracy measurement equipment, that the reported mass properties will be very close to the vehicle?s actual mass properties. This paper will unveil the proposition that the carefully determined mass properties reported by the Mass Properties group has far greater dispersions about the reported values than that expectation. The paper is divided into three parts. Part One expands on basic statistical concepts required to determine mass property parameter dispersions. Part Two derives the algorithms necessary to determine overall vehicle mass property uncertainties. Part Three illustrates Parts One and Two using an example, and produces some representative computer code to implement the algorithms.

%B 64th Annual Conference, Annapolis, Maryland %I Society of Allied Weight Engineers, Inc. %C Annapolis, Maryland %P 36 %8 5/14/05 %G eng %U https://www.sawe.org/papers/3360/buy %9 12. WEIGHT ENGINEERING - COMPUTER APPLICATIONS; 21. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 3360 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE3360 %0 Conference Paper %B 64th Annual Conference, Annapolis, Maryland %D 2005 %T 3379. Mass Properties Using Statistical Techniques %A Biggs, Brent %K 21. Weight Engineering - Statistical Studies %X Over the past 15 or so years, Mass Properties analysis techniques have used the same basic philosophy for calculations. The prediction of mass through a program life cycle can be calculated by adding contingency to a basic mass calculation. As the program matures, this contingency decreases until the program is completed. The contingency schedule is based on a statistical analysis of historical data gathered from the satellite industry. The mass growth tends to follow a standard bell curve. By applying the mean of historical mass growth, statistically there is a 50% chance being under the allocation. The single prediction does not provide insight into the uncertainty of that value. A simple method using the distribution of the historical mass growth to provide a prediction would offer that insight. This prediction, applied at the part level, is presented in statistical terms, easily understood by anyone with a technical background. %B 64th Annual Conference, Annapolis, Maryland %I Society of Allied Weight Engineers, Inc. %C Annapolis, Maryland %P 26 %8 5/14/05 %G eng %U https://www.sawe.org/papers/3379/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 3379 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE3379 %0 Conference Paper %B 61st Annual Conference, Virginia Beach, Virginia, May 18-22 %D 2002 %T 3236. Measurement Uncertainty Analysis for Metrologist %A Bagley, J. L. %K 21. Weight Engineering - Statistical Studies %X Measurements are made in virtually every industrialized process and many of our daily personal activities. Whether you are fueling your car or determining the mass of a pressurized vessel, measurements lie at the heart of your process. How well we make those measurements and how accurately we assess how well they are made can have a major impact on the process outcome. This paper will discuss the analysis of measurement uncertainty used in metrology laboratories, and will expound upon the presentation [3] by the author at the SAWE Regional Meeting in Virginia Beach in November, 2001. The methodology is based upon the ISO Guide to the Expression of Uncertainty in Measurement [4], known affectionately as "The GUM." The goal is to provide a brief functional overview of the analysis and a detailed example. The presentation draws from the techniques taught at Tidewater Community College in the Metrology Specializations under the Associate in Applied Science Degrees in Industrial Engineering Technology and Electronics Technology. %B 61st Annual Conference, Virginia Beach, Virginia, May 18-22 %I Society of Allied Weight Engineers, Inc. %C Virginia Beach, Virginia %P 20 %8 5/18/02 %G eng %U https://www.sawe.org/papers/3236/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 3236 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE3236 %0 Conference Paper %B 61st Annual Conference, Virginia Beach, Virginia, May 18-22 %D 2002 %T 3271. Wing Mass Estimation for Trainer and Fighter Aircrafts in the Predesign Phase based on more than 100 build Aircrafts in th %A Sellner, Werner %K 21. Weight Engineering - Statistical Studies %X The task is to transfer knowledge on data to the next aircraft designer generation Solution of the Task in three steps 1) First Diagram in 1963 2) Database of 50 build Aircraft reached in the year 1972-1977 3) Database of more than 100 International Aircraft and US Aircraft reached in 2002. 1) In 1963 one diagram was found with aircrafts of the 2nd World War Period. In 1964 a collection of mass estimation procedures and mass relevant data of different international aircraft was started. Comparison of issued mass estimation formulas and equations with a common approved data file. Problem of comparison of mass data of aircraft a) International mass standards US UK France Germany USSR b) Company philosophies c) Used Mass Standards on European Fighter and Helicopter programs Solution of the task a) Comparison of international mass standards b) Transfer the aircraft mass data of a common mass standard. We decided to work with the most worldwide used Mil-Std-1374A c) Comparison of all available formulas with 50 build aircrafts d) Development of a new formula in the year 1972/1977 e) Continuing data collecting of international aircrafts f) In the year 2002 data on the 100 aircraft was reached Summary Formulas for ? Total A/C-File ? Split in Trainer/Fighter ? Different periods, different technology, etc. %B 61st Annual Conference, Virginia Beach, Virginia, May 18-22 %I Society of Allied Weight Engineers, Inc. %C Virginia Beach, Virginia %P 112 %8 5/18/02 %G eng %U https://www.sawe.org/papers/3271/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 3271 %1 Non-Member Price: $56.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 56 %4 SAWE3271 %0 Conference Paper %B 56th Annual Conference, Bellevue, Washington, May 19-21 %D 1997 %T 2349. A Light Look at a Comparison Between Empty Aircraft, Actual and Estimated Weights, for Two Time Periods: 1943-1969 & 1970 %A Nagy, B %K 21. Weight Engineering - Statistical Studies %X A Light Look at a Comparison Between Empty Aircraft, Actual and Estimated Weights for Two Time Periods: 1943-1969 & 1970-l988. The purpose of this study is to determine if differences in the accuracy of the state of the art in estimating and achieving aircraft weight empty exists for two periods. Using two tests: the Wilcoxon and means comparison, it was determined that a low probability exists that the two samples are different. Therefore, it is likely that there has not been a change in the accuracy of the state of the art, statistically speaking. %B 56th Annual Conference, Bellevue, Washington, May 19-21 %I Society of Allied Weight Engineers, Inc. %C Bellevue, Washington %P 20 %8 5/19/97 %G eng %U https://www.sawe.org/papers/2349/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 2349 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE2349 %0 Conference Paper %B 50th Annual Conference, San Diego, California, May 20-22 %D 1991 %T 1990. Average ""Passenger and Hand Baggage Weight Survey"" %A Vassilladis, J %K 21. Weight Engineering - Statistical Studies %X For many years (until the mid 80's) Olympic Airways used average standard weight figures for passengers and hand baggage recommended by IATA's Airport Handling Manual, AHM 530 as follows: Adults (M/F): 75 kg, Children (2-12 y.): 35 kg., Infants (below 2y.): 10 kg. After the withdrawing of said standard figures from AHM and the recommendation to the airlines of establishing more realistic figures complying with national regulations and passenger and routes peculiarities, our company proceeded with the weighing procedure described in IATA's AL-IM 53 1. After extended and time consuming statistics, due to several obstacles which we had to confront both at stations abroad and Athens, the results indicated and verified that the real ""passenger and hand baggage"" weights were in many cases higher than the figures actually used. In cases of restricted maxima weights and conditions on limit with the actual weights, this extra weight in the cabin may provoke dangerous conditions, i.e., flight safety and aircraft performance characteristics may be adversely affected. After the results of our study, our intention now is to establish new revised figures corresponding to actual conditions experienced, with the proper approval by the management and the Greek CAA. %B 50th Annual Conference, San Diego, California, May 20-22 %I Society of Allied Weight Engineers, Inc. %C San Diego, California %P 12 %8 5/20/91 %G eng %U https://www.sawe.org/papers/1990/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 1990 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE1990 %0 Conference Paper %B 50th Annual Conference, San Diego, California, May 20-22 %D 1991 %T 2046. Aircraft Weight Confidence Assessment %A Anderson, M %K 21. Weight Engineering - Statistical Studies %X 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. %B 50th Annual Conference, San Diego, California, May 20-22 %I Society of Allied Weight Engineers, Inc. %C San Diego, California %P 14 %8 5/20/91 %G eng %U https://www.sawe.org/papers/2046/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 2046 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE2046 %0 Conference Paper %B 44th Annual Conference, Arlington, Texas, May 20-22 %D 1985 %T 1660. Wing Aspect Ratio Optimization Problems for Transport Turbojet Airplanes %A Gili, P A %K 21. Weight Engineering - Statistical Studies %X The paper concerns the conceptual design phase: definition of the airplane configuration according to the standard requirements. The aim is the optimization of the payload and of fuel consumption which are fundamental elements in the design of a transport airplane. These are required in relation to the external configuration in order to define an optimum wing aspect ratio value. In detail, the work starts out from Breguet's formula, modified for jet airplanes, and develops it as a function of the different parameters. Calculations were performed for different cruising height values, selected from the flight levels usually utilized. The solutions are given as functions of the range, of the cruise flight attitude and of the cruise height. A simple formula is introduced in the flight performance equations for estimating the wing weight. Obviously, for the purposes of this optimization, the fuel consumption during the climb must be taken into account; this evaluation was performed using an energetic method. The computation program consists of a matrix of the variables and parameters, and determines the variation of each one with respect to the others. The results are presented in the form of diagrams and all quantities are represented as variables or parameters. This method, which is a development of that already proposed by the authors for turboprop airplanes, is very easy to use and permits the optimum solution for economy utilization to be found. This situation is determined by certain values for payload and fuel consumption. The external configuration of the airplane may be defined in this way following the most suitable criterion: optimization of the payload, or optimization of the fuel consumption. %B 44th Annual Conference, Arlington, Texas, May 20-22 %I Society of Allied Weight Engineers, Inc. %C Arlington, Texas %P 26 %8 5/20/85 %G eng %U https://www.sawe.org/papers/1660/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 1660 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE1660 %0 Conference Paper %B 44th Annual Conference, Arlington, Texas, May 20-22 %D 1985 %T 1661. Weight Assessment of Electronic Boxes %A Hartley, L A %K 21. Weight Engineering - Statistical Studies %X Prediction and assessment of weights of electronic boxes on a new aircraft are enigmas for aerospace avionics designers and weight engineers. Confidence in box level weight is important for several reasons. Airframe designers must know the maximum weight of each electronic box to be able to provide adequate support structure. System engineers must be confident in the total system weight to evaluate system performance. In addition, cost and weight are often dependent such that an increase in weight will be accompanied by an increase in cost, and all too often the initial weights of electronic boxes are underestimated. This paper does not provide a solution to this problem. It does not provide universal empirical weight relationships to performance parameters. Nor does it describe unique or clever circuit or packaging designs that result in phenomenal weight reductions. It does provide a statistical basis for evaluating weights or electronic boxes, at various times throughout program development, using simple parameters which are universally available. In other words, it provides substantiation for what has usually been "a gut feel based on experience." %B 44th Annual Conference, Arlington, Texas, May 20-22 %I Society of Allied Weight Engineers, Inc. %C Arlington, Texas %P 37 %8 5/20/85 %G eng %U https://www.sawe.org/papers/1661/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 1661 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE1661 %0 Conference Paper %B 37th Annual Conference, Munich, West Germany, May 8-10 %D 1978 %T 1226. Weight Assessment of Electronic Boxes %A Hartley, L A %K 21. Weight Engineering - Statistical Studies %X Prediction and assessment of weights of electronic boxes on a new aircraft are enigmas for aerospace avionics designers and weight engineers. Confidence in box level weight is important for several reasons. Airframe designers must know the maximum weight of each electronic box to be able to provide adequate support structure. System engineers must be confident in the total system weight to evaluate system performance. In addition, cost and weight are often dependent such that an increase in weight will be accompanied by an increase in cost, and all too often the initial weights of electronic boxes are underestimated. This paper does not provide a solution to this problem. It does not provide universal empirical weight relationships to performance parameters. Nor does it describe unique or clever circuit or packaging designs that result in phenomenal weight reductions. What it does is provide a statistical basis for evaluating weights of electronic boxes, at various times throughout program development, using simple parameters which are universally available. In other words, it provides substantiation for what has usually been" a gut feel based on experience." Fortunately, the Offensive and Defensive System avionics developed for the B-1 bomber program do provide a sufficiently large data base to allow development of a statistical basis for evaluating electronic box weights. The data base includes six different functional groups of boxes and represents packaging designs of more than twenty major United States avionics suppliers. In addition, system weight quality histories of the major segments of the Offensive System Group (OSG) avionics and Defensive System Group (DSG) avionics are provided to show the development of the quality of the system level weight estimate. Nomenclature used on the B-1 Avionics program to refer to a distinct electronic box is the term Line Replaceable Unit (LRU). The term LRU is used throughout this paper to denote an electronic box or other distinct hardware entity. %B 37th Annual Conference, Munich, West Germany, May 8-10 %I Society of Allied Weight Engineers, Inc. %C Munich, West Germany %P 28 %8 5/9/78 %G eng %U https://www.sawe.org/papers/1226/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 1226 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE1226 %0 Conference Paper %B 37th Annual Conference, Munich, West Germany, May 8-10 %D 1978 %T 1265. Weight Uncertainty Analysis for Space Shuttle Reinforced Carbon-Carbon %A Henson, J H %A Staton, R N %K 21. Weight Engineering - Statistical Studies %X A new material, Reinforced Carbon-Carbon (RCC), recently developed by Vought for application to the Space Shuttle has presented some unique problems to the Weight Engineer. Density of the material is changed during each of the several production processes. Weight changes during processes are closely monitored and used as a quality control tool. A technique has been developed which uses this preliminary weight data to predict final part weights and tolerance bands on predicted totals. This development has allowed accurate prediction of final weights and early reduction of contingency weight. This paper provides a brief description of the RCC material and process, a description of the analysis techniques used a listing of the computer routine developed for application of the techniques, and results of the analysis. %B 37th Annual Conference, Munich, West Germany, May 8-10 %I Society of Allied Weight Engineers, Inc. %C Munich, West Germany %P 43 %8 5/9/78 %G eng %U https://www.sawe.org/papers/1265/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 1265 %1 Non-Member Price: $21.50; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 21.5 %4 SAWE1265 %0 Conference Paper %B 29th Annual Conference, Washington, D. C., May 4-6 %D 1970 %T 849. Space Shuttle Payload Sensitivities %A Oman, B H %A French, M L %K 21. Weight Engineering - Statistical Studies %X The fundamental purpose of the space shuttle program is to develop a low-cost, economical space transportation system. The current concept to achieve this goal is a two-stage, fully reusable launch system. Payload for a typical mission is 40,000 lb, with a gross liftoff weight of 3. 5 million lb. Careful vehicle optimization will be required to achieve this capability. The low payload fraction causes the payload to be very sensitive to most parameters. Management needs accurate payload sensitivity data in order to make rational design decisions. This presentation shows the sensitivity of space shuttle payload to various parameters, based on a configuration recently investigated by the Convair division of General Dynamics. The main tool used in obtaining sensitivity data for this configuration is the Convair Space Shuttle Synthesis (CVSSS) program, a combined trajectory and weight/sizing computer program that has been in use for several years. One conclusion that can be drawn from the sensitivity data is that a great deal more effort can be invested to reduce weight in the orbiter than in the booster. Another is that engine reliability would have to be relatively low in order to justify the weight penalties or providing engine-out operational capability for the orbiter. %B 29th Annual Conference, Washington, D. C., May 4-6 %I Society of Allied Weight Engineers, Inc. %C Washington, DC %P 19 %8 5/4/70 %G eng %U https://www.sawe.org/papers/0849/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 0849 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE0849 %0 Conference Paper %B 28th Annual Conference, San Francisco, California, May 5-8 %D 1969 %T 791. Rational Weight Estimation Based on Statistical Data %A Ahl, W H %K 21. Weight Engineering - Statistical Studies %X Weight engineering includes three phases of weight determination: estimation, calculation, and measurement. To some weight engineers, estimation is the most important and the most challenging of these three. There has been, are, and will be many estimation methods. Many methods are empirical and some are analytical in nature. This paper discusses a method that is in between empiricism and analysis, and considers it superior to both in many practical respects. This method will be ·referred to as "REBOS", from the title of this paper. REBOS is based on actual weight data of complete vehicles, standardized functional weight coding, weights sub-divided to the degree that weight parameters will be combined uniquely for each of the sub-divisions, and rationally derived parameter combinations which have a linear relationship with weight. The equations resulting from the weight-parameter linear relationships become usable individually for the weight estimation of sub-divisions, and collectively for the weight estimation of major functions and total vehicle. A weight assessment is incomplete until vehicle balance and size adequacy are examined. REBOS includes these considerations, plus moments and products of inertia, since few additional parameters are required to include these latter properties. To indicate REBOS accuracy, standard deviations are computed for estimated functional group and vehicle weights, as well as for estimated vehicle balance and inertias, based on the sample data used. Also, estimated size adequacy indications are summarized for the sample data used. The application of REBOS is practical only when a digital computer is used. Depending on the complexity of the vehicle and the accuracy of the results desired, from 100 to 300 equations must be solved, using a similar quantity of parameters. Average computer time will be from 3 to 15 seconds, depending on the program and the computer used. Empirical methods are considered unconvincing in appearance and proven to be unreliable for extrapolation. Analytical methods are best used for subdivision weight comparisons, but are too complex for total vehicle estimates. REBOS is based on rationality, and purposely uses only readily available parameters so that accuracy tests can be made relatively easy, using additional actual samples as they become available. REBOS can be used for absolute as well as comparative assessment or estimation. Finally, in order to ensure the user's constant understanding and control of the program, unnecessary subdivision of weight elements and inclusion of minor parameters in REBOS is to be avoided. A trade-off between program complexity and output accuracy should always be a consideration. %B 28th Annual Conference, San Francisco, California, May 5-8 %I Society of Allied Weight Engineers, Inc. %C San Francisco, California %P 39 %8 5/5/69 %G eng %U https://www.sawe.org/papers/0791/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 0791 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE0791 %0 Conference Paper %B 27th Annual Conference, New Orleans, Louisiana, May 13-16 %D 1968 %T 661. Best Estimate Method of Determining Space Vehicle Ignition and Cutoff Masses %A Lenning, J J %K 21. Weight Engineering - Statistical Studies %X This paper presents a new method of determining a best estimate of vehicle ignition and cutoff masses which was developed for use in the Saturn program. The text covers the derivation of basic principles and applications to the Saturn S-IVB Stage flight evaluation. The best estimate method is a statistical analysis of independent mass measurement systems combined to arrive at the most probable value for ignition mass and cutoff mass and their respective accuracies. The analysis is essentially a three-dimensional, statistical analysis, developing a joint probability density function from which a solution is determined. This method was developed to utilize the data produced by each measurement system in its purest form. Some measurement systems provide a unique value for ignition mass and cutoff mass. Other measurement systems, such as engine propellant consumption analysis and trajectory reconstruction, inherently provide a linear relationship between ignition and cutoff mass. The best estimate method combines the unique values with these linear relationships to compute the most probable values for ignition andc utoff mass. This technique provides the optimum statistical evaluation of flight-vehicle ignition and cutoff mass by constraining each measurement system to its intrinsic evaluation capability. %B 27th Annual Conference, New Orleans, Louisiana, May 13-16 %I Society of Allied Weight Engineers, Inc. %C New Orleans, Louisiana %P 32 %8 5/13/68 %G eng %U https://www.sawe.org/papers/0661/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 0661 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE0661 %0 Conference Paper %B 27th Annual Conference, New Orleans, Louisiana, May 13-16 %D 1968 %T 691. Confidence Problems in Performance Prediction %A Blake, J T %K 21. Weight Engineering - Statistical Studies %X Test programs for large systems rarely provide enough performance data points to allow prediction of performance guarantee confidence, utilizing statistical techniques developed for academic uses. The system engineer, however, often has enough data for an engineering/management type confidence guarantee. The systems performance data are developed from subsystem characteristics numbers by using a system simulation. Confidence curves for system numbers can be developed by a Mone Carlo of subsystem data distributions. There are problems, however, in the practical applicaiton of this technique. These include an inability to construct an ideal sytem model, and problems in obtaining suitable input data for the model. Each of these problems is considered in detail. The conclusion is drawn that relatively small (say 20) data points per subsystem characteristic is adequate for sytem use; and tht theoretical distribution derived from test data should, in general, not be used for system simulation. %B 27th Annual Conference, New Orleans, Louisiana, May 13-16 %I Society of Allied Weight Engineers, Inc. %C New Orleans, Louisiana %P 25 %8 5/13/68 %G eng %U https://www.sawe.org/papers/0691/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 0691 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE0691 %0 Conference Paper %B 27th Annual Conference, New Orleans, Louisiana, May 13-16 %D 1968 %T 694. Mass Properties Uncertainty Analysis of Aerospace Vehicle Hardware %A Fessenden, R %A Morgan, J J %A Windham, J N %K 21. Weight Engineering - Statistical Studies %X Weight engineering has progressed as an analytical displine to now answer not only the question of how much but also the question of within what tolerance. The purpose of this paper is to dissect the latter question and arrive at a rational approach to the Uncertainty Analyses of Aerospace Verhical Hardware. The basis for the discussion must be built around a consistent set of definitions which are as follows: (a) Nominal Weight - The most probably weight based upon the specific requirements and criteria. It includes contingency for in-scope design development changes. Specific allowances for "growth" are included to the extent specified inthe requirements and criteria. (b) Contingency - That weight which must be added to an estimate to account for lack of detail in the system and/or the type of method used to make the estimate. (c) Growth - Changes in weight due to revisions in requirements and criteria, or concept, and/or solution of major unanticipated development problems. (d) Uncertainty - The variation of weight (or other mass property) about the nominal due to routine but random nature of design development problems, manufacturing tolerances, and natual variations of possible design approaches. Each of the above definitions sets apart a separate subtechnology, however, these subtechnologies cannot be worked as completely separate areas of interest for each has a definite interface with the other. Industry-wide adoption of and adherence to these definitions would allow a base from which future work in the areas of Uncertainty, Growth, Contingency and Weight prediction could build. This paper presents a statistical analysis of all mass properties as related to the definition of Uncertainty above, while being aware of the interrelationships of Nominal Weight, Contingency and Growth. Element uncertainties are established by one of two methods: 1) design analyzed components are evaluated by the historical pattern of components of similar design development, 2) semi-analytical estimates as developed in the weight prediction work are evaluated by a standard statistical method, the standard deviation assuming a normal distribution. (Note how this ties to the job of estimating nominal weights.) Sufficient data has been gathered to use the method on two McDonnell Douglas Corp. programs with satisfactory success. The major problem areas are: a) exact definitions on element size to meet the criterion of independent errors, b) obtaining more historical data to insure consideraiton of all error sources, and c) the presentation of the rather complex technical data in a clear and concise manner to obtain management acceptance. %B 27th Annual Conference, New Orleans, Louisiana, May 13-16 %I Society of Allied Weight Engineers, Inc. %C New Orleans, Louisiana %P 23 %8 5/13/68 %G eng %U https://www.sawe.org/papers/0694/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 0694 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE0694 %0 Conference Paper %B 27th Annual Conference, New Orleans, Louisiana, May 13-16 %D 1968 %T 722. A Method for Determining Probability Distributions for Mass Properties of Systems %A Bond, F C %K 21. Weight Engineering - Statistical Studies %X An analysis is performed to develop expressions for the statistical parameters of system mass properties. It is assumed that the component weights, center of gravity and inertias have known probability distributions. The general forms of the density functions generated are deduced from the calculus of probability whenever applicable. Means and variances of the system mass properties are computed from linear functions of the statistical parameters of the components. The input random variables may be distributed according to any probability law or combination of probability laws for which the moments are known. From conceptual design to detailed specification drawings, the probability laws governing mass properties estimate change. This method may be utilized at any point in the life cycle of system design as it is independent of the particular forms of the distribution used as input. %B 27th Annual Conference, New Orleans, Louisiana, May 13-16 %I Society of Allied Weight Engineers, Inc. %C New Orleans, Louisiana %P 45 %8 5/13/68 %G eng %U https://www.sawe.org/papers/0722/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 0722 %1 Non-Member Price: $22.50; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 22.5 %4 SAWE0722 %0 Conference Paper %B 27th Annual Conference, New Orleans, Louisiana, May 13-16 %D 1968 %T 723. Uncertainty Analysis Plan %A Fisher, D C %K 21. Weight Engineering - Statistical Studies %X This paper discusses a plan for developing a meaningful approach to analyzing mass property uncertainties for each phase of an aerospace vehicle life. Users of a mass property uncertainty analysis are identified. How the application of these values by the users impact vehicle performance and cost is illustrated as a basis for establishing requirements for a meaningful uncertainty analysis technique. Arguments are developed to illustrate the need for acceptance of a universal method and the need for cooperation of the weight engineers throughout industry to develop the method of mass property uncertainty analysis. %B 27th Annual Conference, New Orleans, Louisiana, May 13-16 %I Society of Allied Weight Engineers, Inc. %C New Orleans, Louisiana %P 9 %8 5/13/68 %G eng %U https://www.sawe.org/papers/0723/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 0723 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE0723 %0 Conference Paper %B 26th Annual Conference, Boston, Massachusetts, May 1-4 %D 1967 %T 596. Estimating Cost During Advanced Design by the Use of Weight Analysis %A House, J O %K 21. Weight Engineering - Statistical Studies %X Development cost and material requirements have commonly been based upon the predicted weight of aerospace vehicle components during the advance design phase. These analyses have proven in later reviews to reflect significant accuracy. This approach has been extended to employ a more intensive use of the advance design weight analysis in combination with previous engineering analyses. The approach was tested for its application to advance phase costing of vehicle subsystems and, further, the engineering, development, and qualification testing components of the total cost. The evaluation of several programs reflects a consistent analogy between the vehicle weights and component costs. Provided sufficient accuracy is obtained in the advanced weight analysis, the resulting cost analysis can exhibit a greater degree of confidence. The related cost factors concerning the component material, reliability requirements, method by which the component is to be obtained, etc., must not be reduced in importance. The accuracy of the initial cost analysis is a function of adequate utilization of all available data of each cost factor. In this manner the disadvantage of performing cost analysis on a new type vehicle, as previously experienced with spacecraft systems, is reduced to an acceptable level. The scope of this paper is to introduce the extended use of the advance design weight analysis data in the initial vehicle cost predictions. Reports from previous programs of similar nature (booster vehicles, surface-to-air missiles, short or extended duration spacecraft, etc.) are used to verily the usefulness of this approach. How well the cost factors of a vehicle subsystem repeat between programs can be simplified by further reducing the level of the subsystem groups considered during the analysis. The advance design weight analysis may reveal very little indication of the engineering, development, and testing cost if no reference to a similar vehicle is available. This condition can be rectified by a correlation of the weight analysis with that of a non-similar vehicle for a more detailed component comparison. While the subsystems as a whole may be completely incompatible, a comparison of the components or subsystem groups will likely show a high degree of conformity. It is with this level of hardware that a large percentage of the component costs of the new design can be accurately determined. The ratio of weight of a subsystem attributed to each material, operating function, and method of fabrication should serve as a bias in the comparison between vehicles. A weight breakdown by material is an accepted standard to the mechanics of component pricing. The function that the component is to perform, the expected operating life, and the operating environment provide excellent criteria for rating similar components for comparison of weight and cost. %B 26th Annual Conference, Boston, Massachusetts, May 1-4 %I Society of Allied Weight Engineers, Inc. %C Boston, Massachusetts %P 26 %8 5/1/67 %G eng %U https://www.sawe.org/papers/0596/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 0596 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE0596 %0 Conference Paper %B 26th Annual Conference, Boston, Massachusetts, May 1-4 %D 1967 %T 598. Prediction of Mass Properties for Solid Rocket Motors %A Sivard, L D %K 21. Weight Engineering - Statistical Studies %X The success of a solid rocket motor program often hinges on the Mass Properties Engineer’s ability to accurately predict mass properties from initial design drawings. The mean average (nominal) weight and the weight variation about the nominal of the total motor, propellant, and the expended inerts, are generally the most critical of the mass properties. Costly redesigns and schedule slips can result from the failure to accurately predict these values. Prediction accuracies (calculated versus actual) of within 0.5% for both the nominal values and the variations have been achieved by Aerojet-General. Two sources of information which are often overlooked have been found to be essential in obtaining and maintaining this accuracy. The first is the utilization of historical data from previous programs, and the second is the close coordination and communication between weights personnel and other program personnel. Historical data from past programs are utilized in the prediction of the variables which must be determined for each motor component. The total variations are then derived by a statistical summation. Effective communication and coordination are greatly enhanced by participation of the weights personnel in design review meetings and by documentation controls, including: the specifying of maximum weight on drawings (for items where control of the dispersion is necessary); the receipt and monitoring of all actual weight records; the preparation and publication of Loading Data Reports required for each motor log prior to acceptance by the customer, and the requirement for a weights activity signoff before a drawing or revision is released. %B 26th Annual Conference, Boston, Massachusetts, May 1-4 %I Society of Allied Weight Engineers, Inc. %C Boston, Massachusetts %P 18 %8 5/1/67 %G eng %U https://www.sawe.org/papers/0598/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 0598 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE0598 %0 Conference Paper %B 26th Annual Conference, Boston, Massachusetts, May 1-4 %D 1967 %T 630. Application of Nomograms to Weight and Balance Analysis %A Mandl, J F %K 21. Weight Engineering - Statistical Studies %X During all phases of Weight Engineering, there are situations in which the weight engineer needs an immediate answer to a numerical problem. Some problems can be most rapidly solved by the use of nomograms. This paper presents several practical nomograms for the Weight Engineer. The word “nomography” from nomos, the Greek word for law, refers to the graphical representation of mathematical laws or relationships. The nomograms presented in this paper are the simple alignment type, which require only the use of a straightedge to solve the problem. The nomograms shown, and their manner of construction, are the following: 1. The Nose Gear Reaction of an aircraft for various Gross Weights and C.G.’s. 2. The C.G. change to a vehicle due to: a. relocating a weight within a vehicle b. adding (or removing) a weight to a vehicle. 3. The radius of gyration of a system, for any gross weight and moment of inertia. 4. The moment of inertia change to a system as a result of adding (or removing) a weight to the system. 5. The Tip—back angle of an airplane for various horizontal and vertical C.G.’s. The construction of nomograms is not difficult, when basic principles are understood. Weight engineers with specialized activities can construct nomograms for their particular needs. This paper makes available to the weight engineer another tool, the Nomogram, to help him get the job done more efficiently. %B 26th Annual Conference, Boston, Massachusetts, May 1-4 %I Society of Allied Weight Engineers, Inc. %C Boston, Massachusetts %P 25 %8 5/1/67 %G eng %U https://www.sawe.org/papers/0630/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 0630 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE0630 %0 Conference Paper %B 25th Annual Conference, San Diego, California, May 2-5 %D 1966 %T 529. Statistical Methods in Weight Engineering %A Manners, R D %K 21. Weight Engineering - Statistical Studies %X Statistical methods are becoming increasingly important in many area of weight engineering. As weight requirements on missiles, space vehicles, and aircraft become more complex, so must the analytical tools we use to predict and control their weight and balance. Statistics are frequently used to provide a measure of the accuracy of weight prediction equations and to determine the weight and balance variations of batches of vehicles or components. It is important that any use of statistics in engineering be based on a thorough understanding of the basic statistical principles. This paper has been written to introduce these principles to weights engineers, consequently, the emphasis is on the various applications of statistics in weight engineering. The concepts of populations, samples, and distributions are discussed in detail. Other sections deal with the calculation of probabilities, confidence intervals, and tolerance limits. Techniques are discussed for measuring the accuracy of weight estimating methods. The paper concludes with some remarks on the accuracy of arithmetical calculations and with a suggested bibliography for further reading. A special feature of this paper is the inclusion of all tables necessary for the employment of the various techniques discussed. %B 25th Annual Conference, San Diego, California, May 2-5 %I Society of Allied Weight Engineers, Inc. %C San Diego, California %P 53 %8 5/2/66 %G eng %U https://www.sawe.org/papers/0529/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 0529 %1 Non-Member Price: $26.50; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 26.5 %4 SAWE0529 %0 Conference Paper %B 22nd National Conference, St. Louis, Missouri, April 29 - May 2 %D 1963 %T 366. Extended Usage of Statistics in the Weight Problem Areas %A Vezeau, W A %K 21. Weight Engineering - Statistical Studies %X This paper was presented at the Twenty-second Annual National Conference of the Society of Aeronautical Weight Engineers at St. Louis, Missouri, April 29-May 1, 1963. Some practical applications of statistics will be made upon two sets of weights of an actual rocket. Various estimation problems will be presented as well as testing of hypotheses results. These will involve both parametric and non-parametric methods. Tolerance results are compared with tentative quality control limits. Some suggested extensions of statistical applications such as analysis of variance techniques and tools of Operation Research are presented. %B 22nd National Conference, St. Louis, Missouri, April 29 - May 2 %I Society of Allied Weight Engineers, Inc. %C St. Louis, Missouri %P 24 %8 5/29/63 %G eng %U https://www.sawe.org/papers/0366/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 0366 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE0366 %0 Conference Paper %B 21st National Conference, Seattle, Washington, May 14-17 %D 1962 %T 311. Statistics in Weight Engineering %A Saltzman, D R %K 21. Weight Engineering - Statistical Studies %X This paper was presented at the Twenty-first Annual National Conference of the Society of Aeronautical Weight Engineers at Seattle, Washington, May 14-17, 1962. The importance of statistics in weight engineering lies in its increase of the potential of the individual as an engineer. This comes as a result of prompt and realistic solutions to problems of a particular type and by more efficient use of practical experience. In statistics, data are classified and manipulated so that valuable inferences may be drawn about random variables. The pattern of distribution of these “unpredictable events” is of primary importance. Engineering, the practical application of scientific principles with resulting random fluctuations, especially in the empirical aspects of manufacturing, measuring and testing, is especially susceptible to the methods of statistics. %B 21st National Conference, Seattle, Washington, May 14-17 %I Society of Allied Weight Engineers, Inc. %C Seattle, Washington %P 23 %8 5/14/62 %G eng %U https://www.sawe.org/papers/0311/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 0311 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE0311 %0 Conference Paper %B 13th National Conference, Baltimore, Maryland, May 10-13 %D 1954 %T 99. Statistical Constants in Predicting Equations %A Tysver, J B %K 21. Weight Engineering - Statistical Studies %X A linear predicting equation is presented for which the coefficients are obtained by minimizing the sum of the squares of the percentage errors. Comparison with the ordinary least-squares regression equation (based on actual errors) shows that the two equations can yield substantially different estimates when the range of the variables in the sample to be fitted is large. If percentage errors are more important to the experimenter than actual errors, and if the range of variables is large, the predicting equation presented in this paper is preferable to the ordinary regression equation. %B 13th National Conference, Baltimore, Maryland, May 10-13 %I Society of Allied Weight Engineers, Inc. %C Baltimore, Maryland %P 20 %8 5/10/54 %G eng %U https://www.sawe.org/papers/0099/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 0099 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE0099 %0 Conference Paper %B 10th National Conference, St. Louis, Missouri, May 21-24 %D 1951 %T 59. Application of Statistics to Vendor Casting Weights %A Kunznick, G A %K 21. Weight Engineering - Statistical Studies %X The manufacturing of aircraft castings is usually subcontracted to vendor companies who work from furnished engineering drawings which include dimensions and tolerances for making the parts. Since the weight analyst assumes that the vendor will, on the average, manufacture these castings to the nominal dimensions, his calculations are made on this basis. From past experience, it has usually been found that a comparison of the actual casting weights as received from the vendor and the calculated castings weights based on engineering drawings are seldom in close agreement. The difference between actual and calculated weights are due mostly to the complexity of the parts which does not permit an accurate weight analysis, and to vendor manufacturing techniques. However, since most casting drawings do permit an accurate analysis of the weight, two questions present themselves: (a) Is there a significant difference between the nominal weights of castings as calculated from engineering drawings and the actual weight of castings as received from the vendors? (b) Do some vendors produce lighter weight castings than others? The purpose of this paper is to show how a solution to this problem may be obtained with the use of statistical methods. The data and conclusions shown herein, although obtained from a real case, are for example purposes and for this reason may or may not be representative of industry experience. %B 10th National Conference, St. Louis, Missouri, May 21-24 %I Society of Allied Weight Engineers, Inc. %C St. Louis, Missouri %P 6 %8 5/21/51 %G eng %U https://www.sawe.org/papers/0059/buy %9 21.0. WEIGHT ENGINEERING - STATISTICAL STUDIES %M 0059 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE0059