SAWE Technical Papers

@inproceedings{3020,

title = {3020. Measuring Mass Properties of Aircraft Control Surfaces},

author = {Richard Boynton},

url = {https://www.sawe.org/product/paper-3020},

year  = {2000},

date = {2000-06-01},

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

pages = {63},

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

address = {St. Louis, Missouri},

abstract = {Flutter is of great concern to any pilot, since excessive flutter has caused a number of aircraft to lose control and crash. Although any surface on an aircraft which is exposed to airflow can experience flutter, the most common type of flutter involves the control surfaces such as ailerons, elevators, and rudders. The mass properties of these control surfaces are very critical and have to be measured with great care to make certain that flutter is minimized. Many mass properties engineers ignore product of inertia when measuring control surfaces. We suspect that these engineers will be surprised to discover that the product of inertia unbalance of the control surface can be the key element in eliminating flutter, and that it is vital to measure this quantity.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2454,

title = {2454. Mass Properties Measurement Errors Which Could Have Been Easily Avoided},

author = {Richard Boynton},

url = {https://www.sawe.org/product/paper-2454},

year  = {1999},

date = {1999-05-01},

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

pages = {15},

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

address = {San Jose, California},

abstract = {This paper contains a description of actual case histories of instances where a mass properties measurement error has occurred which could have been avoided (no names mentioned!). Some of these errors resulted from fundamental defects in the procedure; others resulted from very subtle effects which would have been hard to anticipate. And others are painfully obvious, once you realize the problem. However, the fact that these errors occurred emphasizes the need to have a check list, and to have a person who is knowledgeable in mass properties supervising the measurement. The purpose in publishing this history of real errors is to help you avoid these pitfalls. Many of us have made these mistakes (sometimes more than once). We hope that persons reading this paper will supply additional examples to the author, so that I can publish a sequel to this in the future.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2444,

title = {2444. Mass Properties Measurement Handbook},

author = {Richard Boynton and K Wiener},

url = {https://www.sawe.org/product/paper-2444},

year  = {1998},

date = {1998-05-01},

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

pages = {55},

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

address = {Wichita, Kansas},

abstract = {There has been some discussion at recent SAWE International Conferences regarding the creation of a SAWE sponsored mass properties seminar, with the ultimate goal being the certification of Mass Properties Engineers by the SAWE. This paper presents a review of the methods used to measure Center of Gravity Location, Moment of Inertia, Product of Inertia, and Weight. The authors have attempted to discuss all the elements of mass properties measurement, so that this paper can be used as a textbook. This will be condensed and edited at a later date for incorporation into the SAWE Weight Engineering Handbook. Much of the material in this paper has been gleaned from previous papers written by the senior staff engineers at Space Electronics (Boynton, Wiener, and Bell). We have provided a bibliography at the end of this paper which references some of these papers, so that readers wishing to delve further into these subjects can obtain information on mathematical derivations of error sources, etc.},

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

keywords = {03. Center Of Gravity, Mike Hackney Best Paper Award},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2352,

title = {2352. Hidden Errors in Turbine Blade Moment Measurement and How to Avoid Them},

author = {Richard Boynton},

url = {https://www.sawe.org/product/paper-2352},

year  = {1997},

date = {1997-05-01},

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

pages = {26},

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

address = {Bellevue, Washington},

abstract = {By first measuring the static moment of the individual blades and then sorting them into the ideal order, jet engine manufacturers have found that they can greatly reduce the time and effort required to balance the rotor of an engine. More recently a new concept has emerged: if a computer record is kept of the moment of every blade in every engine manufactured, then a damaged blade can be replaced with one of identical moment without the need to disassemble the engine and rebalance the rotor. This saves both money and time, but it places new demands on the accuracy of the moment measurement. If blade moments are in error, then the engine will be unbalanced, resulting in premature wear, or possibly a fatal accident. The concept of blade replacement by matching blade moment requires that the blade be measured with a high degree of accuracy. For example, a 35 pound fan blade might have nominal moment of 17,000 oz-inch and need to be balanced to within 0.5 oz-inch. This represents a required measurement accuracy of 0.003 % of value! Space Electronics manufactures instruments to measure turbine blade moment (these instruments are often called ''moment weight scales''). Our instruments use a new technology which is as much as 40 times more accurate than the conventional knife-edge and load-cell technology that has been employed for the last 30 years. As a result, the moment measurement error of our instruments can be considered insignificant. This has led us to more clearly identify other sources of measurement error which appear to be widespread throughout the industry. The problems show up in two ways: (1) a blade is replaced in the field with one of supposedly identical moment, and the engine is then found to be unbalanced ; (2) a set of blades is measured at Plant A and then sent to Plant B for installation in the engine. If the blades are remeasured at Plant B before they are installed, the data differs from the original set of measurements. However, it often isn't just a simple change in scale factor (i.e. the blades aren't just 0.5% higher in moment at Plant B). There are several factors involved, resulting in what appears to be random differences. I believe I have identified the sources of these errors. This paper identifies each type of error, and gives recommendations for their elimination.},

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

keywords = {03. Center Of Gravity, Mike Hackney Best Paper Award},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2354,

title = {2354. Field Review Measurement of Stores (FRMS) Project Eglin Air Force Base, Florida},

author = {G Evans and A Fitchett},

url = {https://www.sawe.org/product/paper-2354},

year  = {1997},

date = {1997-05-01},

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

pages = {16},

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

address = {Bellevue, Washington},

abstract = {This paper discusses the Field Review Measurement of Stores (FRMS) Project. The FRMS project measures live stores at various worldwide sites. This project is an on- going effort to improve the current database of the mass and physical properties of stores. The data acquired will replace the historical or calculated store mass properties values previously based on manufacturing specification and random samples from production runs. Specifically, this paper addresses the method for collecting meaningful data on stores and store components, the equipment involved, sample/site selection, store selection, measurement parameter definition, measurement operations, program and financial management issues. Finally, comments regarding the production phase of the FRMS project are included.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2296,

title = {2296. Center of Gravity Determination by Video Photogrammetry},

author = {G L Glick and P C Gustafson},

url = {https://www.sawe.org/product/paper-2296},

year  = {1996},

date = {1996-06-01},

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

pages = {10},

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

address = {Atlanta, Georgia},

abstract = {Photogrammetric techniques have been used for industrial measurement for more than a decade. This technique involves the collection of images (either film or digital) from geometrically varied positions. Two dimensional measurements of discrete, identifiable points on the images can then be reduced analytically to three-dimensional coordinates. These coordinates can be determined to an accuracy range of: 1 : 100,000 (0.001'' RMS over a 100'' Length) 1 : l ,000,000 (0.001'' RMS over a 1000'' Length) The application of photogrammetry has been quite varied, ranging from ship building to precision antenna alignment. The three-dimensional coordinates can be analyzed to determine, for example, angular or translational displacement, surface conformance to design, and/or many other alignment and quality assurance tasks. In the manufacture of satellites such as the Space Test Experiment Platform (STEP) Mission 4, video photogrammetric techniques have been applied in an effort to satisfy requirements related to the satellite's mass properties. Specifically discussed in this paper is the combination of photogrammetry with a classic approach to center of gravity (c.g.) determination to achieve rapid, high precision results. In an effort to characterize the satellite's light weight and semi-flexible deployed wings, it is necessary to make mass properties and shape measurements of each wing. Each wing is suspended by a single support cable at an attach point. Targets on the wing and the cable are measured photogrammetrically. This process is repeated for other attach points on the same wing. The data is then analyzed to determine the c.g. of that wing. A robotic video photogrammetric system is used to speed the acquisition of the data (e.g. - a single attach point measurement set is completed in less than 2 minutes). The c.g. was determined in three dimensions to an accuracy on the order of (0.010'' RMS for a 8' by 4' multi-paneled wing, which is well within the specified requirements. Photogrammetric techniques and analysis will also be applied to measure wing/spacecraft alignment, to determine required trim weights and adjustments, and finally to determine the product moment of inertia of the spacecraft.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2329,

title = {2329. Method for Balancing VTOL/STOVL Aircraft},

author = {K Sanders},

url = {https://www.sawe.org/product/paper-2329},

year  = {1996},

date = {1996-06-01},

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

pages = {31},

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

address = {Atlanta, Georgia},

abstract = {A closed-solution balance procedure for the preliminary design of VTOL/STOVL aircraft is presented. The effects of various propulsion concepts on balance and aerodynamic configuration are discussed. It is shown that for a CG location, specified in percentage of MAC, the problem reduces to solving two simultaneous linear equations for the required engine and wing locations, respectively. In contrast, when the CG location is implicitly expressed in terms of longitudinal stability and horizontal tail size parameters, the equations will be non-linear. As opposed to trial-and-error, the present procedure directly exposes the influence of all pertinent design variables, thus providing the designer with valuable and time-saving insights to arrive at a balanced configuration. A table depicts fourteen basic VTOL concepts. Of' these, balance equations are derived and discussed for five ''lift/cruise'' types and for one fan-in-wing type. For any other V/STOVL concept, the pertinent equations can be easily set up, and as many component weight terms added as the case may require. A constant-bleed hover reaction control systems (RCS) is discussed in appendix A. Spreadsheet examples of the procedure are given in appendix B for a Lift+Lift/Cruise, and in appendix C for a fan-in-wing design. * An outline of this paper was given in SWR-7 at the society's First Annual Southwestern Regional Meeting, 11 October 1974. The subject was a key element in preliminary design studies for the Sea Control Ship VFA, conducted at the former Advanced Aircraft Systems Program Office of the Naval Weapons Center, China Lake, in the 1972-1975 period. The author was then head of the Aircraft/RPV Predesign and Advanced Technology Branch. Interest in the current JAST development program prompted this formalized and expanded issue.},

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

keywords = {03. Center Of Gravity, Mike Hackney Best Paper Award},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2244,

title = {2244. New Moment Balance Machine for Turbine Blade Measurement},

author = {Richard Boynton and K Wiener},

url = {https://www.sawe.org/product/paper-2244},

year  = {1995},

date = {1995-05-01},

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

pages = {17},

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

address = {Huntsville, Alabama},

abstract = {Balance is a major factor in determining the reliability and service life of turbine rotors used in jet engines or power plants. The task of balancing a completed rotor can be greatly simplified if the individual blades are first measured and sorted according to static unbalance moment. They are then assembled in the rotor in such a way as to compensate for hub unbalance, resulting in an assembly that is approximately balanced. Final balance is then done on a horizontal spin balance machine. Space Electronic has designed a special static balance machine to measure turbine blade moment. Previously this task has been accomplished using knife edge and load cell technology that was developed in the 1950?s. Our machine combines force rebalance with flexure pivots to result in sensitivity and accuracy that is at least 20 times better than the existing state of the art. This paper discusses the various steps in the process of balancing a turbine rotor. the new Space Electronics machine is described in detail. Fixturing is a limiting factor in blade moment measurement. We discuss some of the problems and propose some novel solutions.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2280,

title = {2280. Development of Alternate Forward C.G. Limits for Improved Takeoff Performance},

author = {L Gillman},

url = {https://www.sawe.org/product/paper-2280},

year  = {1995},

date = {1995-05-01},

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

pages = {13},

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

address = {Huntsville, Alabama},

abstract = {Alternate forward Center of Gravity limits can be used to improve aircraft performance. In the past, this type of performance improvement has been limited to a unique alternate forward CG for a given model. The paper discusses a proposal to the FAA that resulted in a new policy, allowing the use of multiple customer selected alternate CGs for improved takeoff performance. The paper emphasizes the Weight Engineering aspects of the FAA policy. The existing use of loading systems is first reviewed. The use of curtailments to the certified limits for developing the operational limits is discussed. The discussions with the FAA are summarized, and the resulting policy allowing revised use of alternate CGs is discussed. The certification and operational criteria that were specified by the FAA for use with the multiple alternate CGs are covered. Specific application of the policy to the 767-300 is shown through examples of the Weight and Balance Manual, Airplane Flight Manual, and a generic loading system.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2192,

title = {2192. A Non-Contacting Vertical Alignment System for Mass Properties Measuring Instruments},

author = {G H James III and J E Suazo and R C Varga},

url = {https://www.sawe.org/product/paper-2192},

year  = {1994},

date = {1994-05-01},

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

pages = {38},

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

address = {Long Beach, California},

abstract = {Sandia National Laboratories recently had a need to balance and measure the mass properties of several large, lightweight objects. These objects were too compliant and asymmetric for traditional alignment procedures using contact sensors. Therefore, a non-contact system for alignment of these test objects was developed. Since a well defined geometric axis was not available for these test objects, a reference axis was defined using two planes through the test object. At the bottom plane, noncontacting laser triangulation sensors measure the variation of the surface of the object and a best-fit circle is calculated. The reference axis is defined to pass through the center of this circle at the bottom plane and through the center of a reference target at the top plane. Digital video analysis is used to calculate angular orientation and reference target motion during a slow rotation of the test object. The top and bottom plane offsets of the reference axis from the balancing machine spin axis and the required corrective adjustments are then calculated. This new procedure requires two to three iterations to converge to the final alignment and can be accomplished in less than two hours. The current implementation can align objects to less than .001 inches at the two planes with final requested adjustments of a few ten-thousands of an inch. This procedure also measures several hundred data points around the circumference of the test object, instead of the standard four contact measurements. This allows the procedure to be more robust, since the object does not have to be perfectly symmetric. Also, the increased automation shortens the operator learning curve and lessens the chance of operator error. And finally, since all calculations are performed in software, a record of the measurements and alignment parameters are available for later reference. The hardware and processes developed for non-contact alignment open up a new realm for balancing and testing of very large and lightweight test objects.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2232,

title = {2232. Determination of the Manager's Reserve Guideline for the Space Shuttle Xo Center of Gravity},

author = {Robert Hundl},

url = {https://www.sawe.org/product/paper-2232},

year  = {1994},

date = {1994-05-01},

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

pages = {29},

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

address = {Long Beach, California},

abstract = {The space shuttle's Xo center of gravity (CG) requires a major consideration when designing the descent phase of a mission. The space shuttle's forward Xo CG Limit during descent at Mach 3.5 is 1079.0'' (27.4066 m) for Return To Launch Site (RTLS) and 1076.7'' (27.34818 m) for Nominal, Transoceanic Abort Landing (TAL), Abort Once Around (AOA), and Non-Deploy scenarios. Recently, forward Xo CG shifts a few months before launch have required late 'fixes'' to be made. These ''fixes'' often require rework, reverification, and/or overtime which increase costs and may take available resources away from other missions. Current payload manifesting at various milestones have made the flights Xo CG at or very near the forward limit. To aid managers when manifesting additional items on a flight, historical and current flight mass properties data were analyzed to determine if a guideline could be established. This guideline would be based upon potential impacts of unknowns following a particular milestone. The establishment of this guideline should provide managers an adequate tool for minimizing late 'fixes'' while maximizing the space shuttle's carrying capabilities. During the latter stages of a mission's flow, the Xo CG was usually found to move forward. The last chance to manifest payloads occurs at the Flight Planning and Stowage Review (FPSR). This meeting precedes a critical milestone for flight design. A 0.5'' (0.0127 m) margin at this time was determined to be adequate for most flights while allowing maximum manifesting capability. On the average, primary payload mixes for future flights are projected to have a more forward combined Xo CG than past flights; thus, this guideline will become an important tool for managing a flight and reducing program costs.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2163,

title = {2163. Aircraft Weight and Center of Gravity Scatter Band at Delivery},

author = {B Huber},

url = {https://www.sawe.org/product/paper-2163},

year  = {1993},

date = {1993-05-01},

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

pages = {36},

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

address = {Biloxi, Mississippi},

abstract = {The airlines are sometimes surprised and want to know why, at delivery, considerable differences occur in weight and center of gravity since the aircraft configuration definition has not changed. For example 400 to 500 kg differences have been observed on two A310s with an empty weight of about 80,000 kg at delivery. The analysis of the weight and center of gravity scatter for delivered aircraft has been made for all A310 and A320 aircraft delivered until the beginning of 1993, which cumulated in about 200 A310s and 400 A320s. The reasons for this scatter have been identified and quantified. Four reasons which explain generally the results of the statistical analysis made on A310 and A320 have been found to be of major concern : OEW determination Aircraft definition difference Variations in manufacturing Aircraft condition, which explain generally the results of the statistical analysis made on A310 and A320.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2174,

title = {2174. Measuring Mass Properties of the Brilliant Pebbles Satellite},

author = {Richard Boynton},

url = {https://www.sawe.org/product/paper-2174},

year  = {1993},

date = {1993-05-01},

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

pages = {24},

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

address = {Biloxi, Mississippi},

abstract = {Small kinetic energy ''Kill Vehicle'' satellites have very limited fuel capacity and consequently have tight mass properties specifications. To further complicate the measurement problem, these satellites do not have precision hard points or a smooth outer surface. This paper includes a brief overview of the Brilliant Pebbles program, with discussion of the unclassified aspects of the flight. It also presents the very complex measurement sequence which was required. Fixturing error is minimized by mounting the satellite in a precision cylindrical cage, determining its position in the cage using a coordinate measuring machine, and finally using a work reversal concept to eliminate the effects of fixture misalignment.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1989,

title = {1989. Aircraft Weighing: A Focal Point in Mass Properties Engineering},

author = {B Huber},

url = {https://www.sawe.org/product/paper-1989},

year  = {1991},

date = {1991-05-01},

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

pages = {58},

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

address = {San Diego, California},

abstract = {Due to the size and weight of the new members of the Airbus family, the A330/A340, and the increasing number of aircraft being delivered, Aerospatiale was forced to build a new weighing facility in Toulouse. Based on the excellent results obtained with mechanical scales installed for the Concorde, a similar equipment has been chosen, offering increased possibilities and better precision. The scale mechanism is installed in a ''basement'' with platforms level to the floor. It is a stationary installation, the aircraft is rolled on the platforms and is weighed on wheels. The purpose of this paper is to discuss 1) the installation, characteristics, and capabilities, 2) the French Regulation applied to weighing instruments, 3) the scale accuracy, 4) the results on aircraft weight and balance determination and precision, and 5) the delivery aircraft weighing and weighing report. Furthermore emphasis is given to the advantages for delivery aircraft weighings. The time for weighings is reduced to a minimum (less than 10 minutes compared to two hours for a weighing with mobile electronic ramps and six hours with load cells on jacks). It is easy to operate -not more than two operating personnel are required. The installation is always operational, nothing has to be moved or to be adjusted (no reconfiguration for various wheel combinations). The installation has outstanding accuracy and reliability.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2023,

title = {2023. Is a Spacecraft's Orbit Determined by A) Its Center of Mass Or B) Its Center of Gravity},

author = {G Jones},

url = {https://www.sawe.org/product/paper-2023},

year  = {1991},

date = {1991-05-01},

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

pages = {28},

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

address = {San Diego, California},

abstract = {Nearly every working day, someone will ask a mass properties engineer where a CG is located. He or she answers with the location of the center of mass, which is not exactly the same thing, but is the same for all practical purposes. Metrology specialists treat centers of gravity and centers of mass identically. This study explains the difference in CG and CM, illustrated by the trivia question which provides the paper title.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2026,

title = {2026. Three Axis Center of Gravity Determination on a Spin Balance Machine},

author = {J M McIntyre and T S Nishimoto},

url = {https://www.sawe.org/product/paper-2026},

year  = {1991},

date = {1991-05-01},

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

pages = {22},

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

address = {San Diego, California},

abstract = {A method is presented for locating the center of gravity of a spacecraft along the spin axis by modifying the spin balance procedure. The resulting ''Z'' cg determination is inexpensive, accurate, easily accomplished, and has the additional characteristics of simplifying spacecraft processing. The method is based on performing a second spin balance about an arbitrary axis which is parallel to, but shifted from the original spin axis. A parameter sensitivity analysis together with a special purpose test performed on a Star 37 motor show the method to be valid and practical.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1936,

title = {1936. Mass Properties Measurement in Japan},

author = {Richard Boynton and R Bell},

url = {https://www.sawe.org/product/paper-1936},

year  = {1990},

date = {1990-05-01},

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

pages = {37},

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

address = {Chandler, Arizona},

abstract = {The authors have recently installed a mass properties instrument conservatively capable of measuring satellites weighing more than 13,200 pounds at the Japanese Space Center (NASDA). During the installation, we were able to view some of the current mass properties equipment at various installations in Japan and to also gain information on the scope of spacecraft and rocket manufacturing in Japan. This paper summarizes some of the features of the new mass properties measuring machine (probably the largest gas bearing mass properties instrument in the world), and provides a detailed error analysis of moment of inertia measurement using an inverted torsion pendulum. Finally, we give our observations regarding some of the myths about the Japanese people and what it is like for an American engineer to work at a Japanese space center.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1939,

title = {1939. Techniques for Calculating and Minimizing Cumulative Error in Multiple Instrument CG Measurements},

author = {G A Jones},

url = {https://www.sawe.org/product/paper-1939},

year  = {1990},

date = {1990-05-01},

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

pages = {26},

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

address = {Chandler, Arizona},

abstract = {The process of measuring the CG of large test items often involves the use of several different instruments. These may include three or more load cells, length scales, calipers, micrometers, calibrated weights, machined test fixtures, vernier inclinometers, optical measurement systems and so on. In any mass properties lab, some of the instruments will be of the highest precision, whereas other equipment items may suffer somewhat from cost compromise. When using several instruments together, the measurement uncertainty of each instrument contributes in a definite way to the uncertainty of the overall measurement. The mass properties engineer must know how the uncertainty tolerances of each instrument ''stack up,'' so that he can estimate the uncertainty tolerance of his final answer. Herein the author proposes a method for tolerance stacking which requires the investigator to Derive, Differentiate, and Substitute (DDS). After developing the DDS method, the author suggests techniques for using the DDS function to not just find the uncertainty, but also to minimize the cumulative uncertainty. DDS is a measurement optimization technique, which allows the mass properties engineer to get the greatest advantage out of his finest instruments and to arrange his less precise instruments in such a way as to minimize the effect of the larger uncertainty they introduce.},

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

keywords = {03. Center Of Gravity, Mike Hackney Best Paper Award},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1884,

title = {1884. CG Measurement Error Analysis - New Technology Has Changed All the Rules},

author = {Richard Boynton and K Wiener},

url = {https://www.sawe.org/product/paper-1884},

year  = {1989},

date = {1989-05-01},

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

pages = {28},

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

address = {Alexandria, Virginia},

abstract = {This paper re-evaluates the basic methods for measuring center of gravity in light of the dramatic innovations in force measurement which have taken place in the last few years. The authors attempt to include all sources of error. These include the ability of the test operator to reliably determine the position of the unit under test relative to the reference datum of the instrument (''fixturing error''), effect of instrument lean, sensitivity (the smallest cg shift which can be detected), and linearity. The type of cg instruments analyzed are: the gas bearing rotary table moment measuring concept (using both load cells and the new active moment transducers), the multiple point weighing method (''three load cell method''), the moment of inertia method, mechanical rebalance methods, and spin balance cg determination. Typical errors for different test objects are determined, and recommendations are made for different applications. The authors conclude with an error summary of current available cg measuring instruments.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1827,

title = {1827. A New High Accuracy Instrument for Measuring Moment of Inertia and Center of Gravity},

author = {Richard Boynton and K Wiener},

url = {https://www.sawe.org/product/paper-1827},

year  = {1988},

date = {1988-05-01},

booktitle = {47th Annual Conference, Plymouth, Michigan, May 23-25},

pages = {17},

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

address = {Plymouth, Michigan},

abstract = {This paper describes a new class of mass properties measuring instruments which exhibit performance that is 10 to 100 times better than any measuring machine of conventional design. This extraordinary magnitude of improvement is the result of high speed closed-loop moment sensing. The basic concept is similar to the old re-balance CG instruments which contained a counterbalance weight and a motor drive to reposition this weight so that a moment balance was achieved. However, unlike the old 'soft' technology which was very slow and unstable, the new technology achieves balance in less than one second and, because of the high loop gain, is also very stiff and stable. Unlike most technology improvements, there is no tradeoff. The new concept improves all of the performance criteria: sensitivity, dynamic range, linearity, stiffness, and overload protection. This sounds too good to be true, but extensive tests on a number of instruments of different sizes have failed to show up any disadvantage to the new method.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}