SAWE Technical Papers

@inproceedings{0588,

title = {588. The Determination of Center of Gravity Limits and Their Effect on Safety and Performance of Transport Aircraft},

author = {G H Cathey and G R Smythe},

url = {https://www.sawe.org/product/paper-0588},

year  = {1966},

date = {1966-05-01},

booktitle = {25th Annual Conference, San Diego, California, May 2-5},

pages = {20},

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

address = {San Diego, California},

abstract = {The effect of center of gravity limits on the design of a typical jet transport, its structural weight and performance, and the design criteria and aerodynamic characteristics which establish the allowable center of gravity range are presented in qualitative terms. 

Effects on aircraft safety and performance from inadvertently exceeding the center of gravity limits are briefly described. 

Equations used in evaluating aircraft stability and control characteristics are presented with notations of the aerodynamic and geometric terms used. Certain aerodynamic characteristics have been neglected in the development of these equations to simplify the presentation. Some of the characteristics neglected are the type of control system, aeroelastic effects, power effects, and drag. In a more comprehensive study of stability and control, these characteristics would have to be considered. 

Methods are given for improving performance capabilities of aircraft in service by altering the normal center of gravity limits for operations under special conditions. 

The effects on an airplane configuration resulting from a design which imposes an excessive range in center of gravity loading limits, an example of how performance is penalized, and the effects of these penalties on the operational economics of a typical transport aircraft are shown.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{0426,

title = {426. Use of the SC-4020 Data Plotter for C.G. Diagrams},

author = {A G Winnett},

url = {https://www.sawe.org/product/paper-0426},

year  = {1964},

date = {1964-05-01},

booktitle = {23rd National Conference / Sheraton, Dallas Hotel, Southland Center, Dallas, Texas May 18-21},

pages = {30},

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

address = {Dallas, Texas},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{0453,

title = {453. A Method of Measuring the Radial Center of Gravity of a Large Missile},

author = {J B Harris},

url = {https://www.sawe.org/product/paper-0453},

year  = {1964},

date = {1964-05-01},

booktitle = {23rd National Conference / Sheraton, Dallas Hotel, Southland Center, Dallas, Texas May 18-21},

pages = {31},

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

address = {Dallas, Texas},

abstract = {This paper presents a method of measuring and evaluating the radial center of gravity of a large missile by suspending the missile as a pendulum and measuring its tilt by means of a plumb bob. The test apparatus is low cost and unsophisticated but has been used to measure radial center of gravity coordinates with an accuracy of plus or minus 0.5% of missile diameter. Minor improvements would enable radial center of gravity coordinates to be measured within 0.25% of missile diameter. The apparatus and analysis are described in detail. Photographs of the apparatus and sample calculations are included in the paper.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{0315,

title = {315. Precision Static Center of Gravity Measurement},

author = {L G Schwartz},

url = {https://www.sawe.org/product/paper-0315},

year  = {1962},

date = {1962-05-01},

booktitle = {21st National Conference, Seattle, Washington, May 14-17},

pages = {11},

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

address = {Seattle, Washington},

abstract = {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 weighing and location of the Center of Gravity of rocket motors, reentry vehicles, and various other bodies involved in aero space programs has received ever increasing attention during the past few years. During this period we have seen considerable improvement in the instrumentation involved in these measurements. 

Ancillary equipment used in conjunction with the basic measuring equipment has become a large part of some weighing and CG locating systems. Recording and computing equipment together with associated analog to digital converters in some cases may become a quite sizeable dollar portion of the overall system. 

This paper points out the importance of the placement configuration of load transducers in the reaction measurement method of CG determination and suggests two other methods. These are a single beam system and a repositioning system, both of which are inherently more accurate than any of the reaction measurement methods. Three methods of reaction measurement, the single beam system and the repositioning system are investigated and discussed. A comparison is made of three reaction measurement configurations. The single beam system is primarily for small bodies; therefore a direct comparison between it and the other methods is not made. The repositioning system is not directly compared with the reaction methods because with its basic simplicity no detailed analysis is required to show its accuracy advantage. 

It may be concluded that, whenever possible, a system which repositions the test body so that its CG is placed in the plane of the support pivot axis, is always superior to a reaction measurement system. In some instances the size of the body or required method of handling may preclude the use of such a system. If a repositioning system cannot be used, a reaction measurement system which disposes the nominal CG over, or very near to, one reaction point should be used. Such an arrangement should always yield better results than a conventional configuration which disposes the nominal CG midway between widely spaced reaction points.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{0330,

title = {330. The Protective Level Concept of Airplane Balance Control},

author = {J R McCarty},

url = {https://www.sawe.org/product/paper-0330},

year  = {1962},

date = {1962-05-01},

booktitle = {21st National Conference, Seattle, Washington, May 14-17},

pages = {62},

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

address = {Seattle, Washington},

abstract = {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. It is the purpose of this report to present the data and statistical techniques that have been collected, analyzed and developed pursuant to the airplane balance control system which will be known as the Protective Level Concept. 

Although we would like to suggest that this concept is completely new, it is in reality the evolutionary result of pervious work done by United Air Lines, primarily in connection with passenger distribution and average baggage weight. Nevertheless, the application of statistical techniques to the airplane balance control problem, and the greater control and knowledge associated therewith, is considered to be a significant development in the field of airline weight and balance.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{0336,

title = {336. Establishment of Clearly Defined Weight and C.G. Tolerances Acceptable to New Aircraft for Benefit of Manufacturers},

author = {G W Benedict and C A Hangoe},

url = {https://www.sawe.org/product/paper-0336},

year  = {1962},

date = {1962-05-01},

booktitle = {21st National Conference, Seattle, Washington, May 14-17},

pages = {30},

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

address = {Seattle, Washington},

abstract = {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 problem of communication between the aircraft manufacturer and the airline is often obscured by the absence of clearly stated and well defined requirements. The problem can be aggravated further by such considerations as language barriers, manufacturers and airline attitudes and, above all, lack of opportunity for oral exchanges. 

In dealing with an airline customer, the manufacturer of a saleable aircraft type will frequently need to restate the description and the capability of his product and its fitness to mesh with the customer's requirements while on the other hand, the customer might labor under misdirected notions of just what can or cannot be accommodating. 

In the viewpoint of some of the manufacturers, the weight and balance sections of their specifications, deal adequately with needs of any airline in particular and in the option of airlines the opposite may be the case. Who knows the exact or even the cross-sectional opinions prevailing. 

An opinion survey might prove meaningful in this regard. This paper includes the results of such a survey. The survey was conducted by the means of a questionnaire mailed to manufacturers and airlines on a world-wide basis. A total of 72 questionnaires were forwarded to aircraft manufacturers, to airlines and to associated and/or governmental agencies. 34 completed questionnaires were returned or 47% of the total contacted responded. 

In regard to satisfaction with specification centre of gravity and weight tolerances, the returned questionnaires revealed that 5 of 30 airlines were satisfied with current practices, 12 airlines were looking for improvements while the remaining 13 airlines were non-committal. However, in responding to the questionnaire in general all but 2 of the latter airline had some opinions on the questions raised, so it is legitimate to infer that they were not altogether satisfied. On the strength of the returns it has been shown that the great majority of the airlines favor the introduction of some new thoughts and specification stipulations. Of other respondents, governmental agencies and manufacturers, only one manufacturer indicated a need for improvements.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{0282,

title = {282. A New Emphasis on Center of Gravity},

author = {G W Benedict},

url = {https://www.sawe.org/product/paper-0282},

year  = {1961},

date = {1961-05-01},

booktitle = {20th National Conference, Akron, Ohio, May 15-18},

pages = {11},

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

address = {Akron, Ohio},

abstract = {This paper was presented at the Twentieth National Conference of the Society of Aeronautical Weight Engineers at Akron, Ohio, May 15 - 18, 1961. The advent of the jet transport has brought with it changes in operating techniques which have resulted in a requirement for more specific balance information for the purpose of setting the horizontal trim more precisely prior to the airplane takeoff. The takeoff procedure is reviewed emphasizing those periods during the takeoff when the control forces are most critical. Stick force characteristics as a function of trim settings are presented for these takeoff periods which illustrate the effect of rotation speed, critical climb speed, gross weight, and center of gravity. The effect of various tolerances on the center of gravity information used for making the trim setting is examined. Procedures which establish the center of gravity as a function of fuel, cargo, and passenger loading are proposed.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{0293,

title = {293. A Low-Cost, Practical Approach to the Actual Measurement of the Horizontal and Vertical Center of Gravity of a Small Missile},

author = {R Warren},

url = {https://www.sawe.org/product/paper-0293},

year  = {1961},

date = {1961-05-01},

booktitle = {20th National Conference, Akron, Ohio, May 15-18},

pages = {20},

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

address = {Akron, Ohio},

abstract = {This paper was presented at the Twentieth National Conference of the Society of Aeronautical Weight Engineers at Akron, Ohio, May 15 - 18, 1961. Actual measurement of an aircraft's horizontal center of gravity has for years been a standard practice. However, center of gravity location in the vertical reference system has not been a critical parameter and therefore, the standard practice in this respect has been to rely on calculated values. 

This approach is entirely inadequate when confronted with high angular thrust values under ballistic conditions that have appeared on a current project at Columbus Division of North American Aviation, Inc. In July 1960, the Army Rocket and Guided Missile Agency, through the Cleveland Ordnance District, awarded a development contract for the Roadrunner Target Missile System. 

The basic configuration of the North American designed Roadrunner Target Missile pointed out the necessity for knowing the exact vertical as well as the horizontal location of the missile center of gravity. The sustaining power source for climb and cruise is a ramjet engine, mounted high on the rear of the missile. For propelling the Target Missile to a speed at which this ramjet will produce thrust, a solid propellant booster with a fixed cant angle nozzle is mounted below the missile body. The Roadrunner Target Missile is zero-length launch and behaves according to ballistic laws for approximately the first three seconds after boost ignition. At this time, aerodynamic surfaces are effective to a point where missile attitude may be controlled. From the conditions that exist, it can readily be seen that the booster thrust must be directed through the total center of gravity. Otherwise, within three seconds the missile will have pitched or yawed out of control causing structural damage, tumbled gyros, and it may not even reach engine light off speed. More serious misalignment of booster thrust could easily pitch the missile into the ground in front of the launcher, or in the other direction, drive the missile into a loop, impacting behind the launch pad.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{0064,

title = {64. Fuel Management as a Means of Controlling Center of Gravity Travel},

author = {J C Hanes},

url = {https://www.sawe.org/product/paper-0064},

year  = {1951},

date = {1951-05-01},

booktitle = {10th National Conference, St. Louis, Missouri, May 21-24},

pages = {8},

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

address = {St. Louis, Missouri},

abstract = {In the past, the control of the airplane center of gravity travel due to fuel consumption has been solved by letting the pilot select his fuel tanks in such a manner that proper airplane balance was maintained; but today when fuel consumption rates of the order of 30,000 pounds per hour is not uncommon, the pilot would be doing nothing but operating his tank selector, with no time left to look at the innumerable instruments, radar scope and fire his guns, let alone trying to fly the airplane. Up until recently, the effect of 'fuel slosh' on airplane center of gravity travel has generally been negligible. Fuel was treated as a solid that varied horizontally and vertically as it was consumed, with no thought given to the changes in fuel center of gravity with the change in airplane attitude.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{0040,

title = {40. Determination of Center of Gravity Limits From Flying Quality Considerations},

author = {G G Kayten},

url = {https://www.sawe.org/product/paper-0040},

year  = {1949},

date = {1949-05-01},

booktitle = {8th National Conference, Dayton Biltmore Hotel, Dayton, Ohio, May 23-26},

pages = {13},

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

address = {Dayton, Ohio},

abstract = {Control of airplane center-of-gravity locations is of course a matter of primary concern to the aeronautical weight engineer. Because of the specialization demanded by the complexities of modern aircraft development, however, the weight engineer is ordinarily unable to participate in the analysis of the factors which dictate the limitations on allowable c.g. range. 

The present paper represents an attempt to outline the aerodynamic considerations on which the allowable forward and aft c.g. limits are based. It is believed that an appreciation of these aerodynamic aspects will be of interest and benefit to the weight engineer, although it is not anticipated that the discussion will simplify the problem of compliance with the resultant loading restrictions.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{0030,

title = {30. The Effect of Center of Gravity on Performance},

author = {E V Argabright},

url = {https://www.sawe.org/product/paper-0030},

year  = {1944},

date = {1944-04-01},

booktitle = {Denver Colorado, April 17, 1944},

pages = {5},

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

address = {Denver, Colorado},

abstract = {The effect of weight on performance is well known, and its importance is generally recognized. The effect of balance or center of gravity location on stability and flying safety apparently is not quite as well known, but all authorities agree that it is extremely important. These points, that is, effect of weight on performance and the effect of balance on stability and safety, could hardly be over-emphasized. The effect of center of gravity position on speed and range has been seriously over-emphasized however, and without detracting from its importance as regards stability and safety, I will show by results of studies and carefully run experiments that the effects of center of gravity location on speed and range is entirely negligible.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{0025,

title = {25. The Effect of Overload and Unbalance on Long Range Operation},

author = {J B Childers},

url = {https://www.sawe.org/product/paper-0025},

year  = {1943},

date = {1943-01-01},

booktitle = {1943},

pages = {10},

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

address = {,},

abstract = {Since the beginning of this war, an increased demand for longer range, more endurance and greater load carrying ability has been forced on aircraft designed for much shorter distances and smaller loads. The number of fatal crashes resulting from this demand quickly convinced the Air Forces of the fallacy of overloading and unbalancing their ships. However, since the problem of increasing the useful load is very acute, our aircraft are still overloaded in many cases, almost to the critical point, from the standpoint of stability. 

This type of loading and its effect on long range operation is the subject with which this report is concerned. The purpose of this report is not to present an involved aerodynamic and mathematical analysis of the variation of range with weight, but rather to more or less give those directly and indirectly concerned with this problem an inkling of the fundamental theory involved and illustrate how serious the results of overloading can become on the range of modern bombers.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{0009,

title = {9. Aircraft Balancing and Center of Gravity Control},

author = {W A Semion},

url = {https://www.sawe.org/product/paper-0009},

year  = {1942},

date = {1942-01-01},

booktitle = {16th Dinner Meeting of the Los Angeles Chapter, Western Division of the Society of Aeronautical Weight Engineers, Inc., Los Angeles, California, January 16, 1942},

pages = {13},

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

address = {Los Angles, California},

abstract = {Proper airplane balancing and center of gravity location is one of the basic factors which insure successful design. Due to external and internal forces, and moments acting upon the airplane in flight, its motion is performed about its center of gravity. The equations of motion and of static and dynamic stability of the aircraft take into consideration its weight and center of gravity location, as well as mass moment of inertia. All factors combined affect the aerodynamic performance and the load carrying capacity of the aircraft. 

Both the weight and the center of gravity, if roughly estimated, are subject to considerable variation. As the design progresses, the weight, in the great majority of cases, increases at a certain rate, while the center of gravity has a considerable tendency to shift toward the tail. 

Inasmuch as the proper longitudinal, or fore and aft, center of gravity location plays the most important part in the aircraft design and operation, the vertical center of gravity location, even though significant, is far less important. 

The center of gravity of an airplane may travel within short limits (several inches) determined by the actual flight testing. In the design stage, it is possible to set a conservative limit as to the range of CG travel on the basis of wind-tunne1 test data. 

This paper offers a list of practical suggestions that may be used by the airplane designer or aircraft weight control engineer as well as by the operator, whether military or commercial. Some of the listed means of aircraft balancing and center of gravity control are applicable strictly to aircraft that are in the process of design, while others can be app1ied to the airplanes in actual service, as well as to the ones still on the drafting board. At times it is necessary to combine several of these means in order to avoid weight penalty and to correct the unbalanced condition of the aircraft.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{0002,

title = {2. Airplane Weight and Balance Control},

author = {S Shatto},

url = {https://www.sawe.org/product/paper-0002},

year  = {1940},

date = {1940-07-01},

urldate = {1940-07-01},

booktitle = {16th Semi-Annual Engineering and Maintenance Conference Air Transport Association of America, Hotel St. Paul, St. Paul, Minnesota, July 15-17, 1940},

pages = {11},

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

address = {St. Paul, Minnesota},

abstract = {(As taken from Part I of proceedings of Engineering and Maintenance Conference of the Air Transport Association of America at St. Paul, Minnesota on July 15, 16 and 17, 1940) 

I shall give you a resume of Weight Control Procedure which we have prepared by thoroughly studying some of the other operators and visiting airplane manufacturers. The importance of weight control has been very evident in the past few years; all operators are wanting to carry the maximum pay-load possible at all times. It is accurate weight control that makes it possible. 

The object of Weight Control, both from the viewpoint of the air carrier and from that of the Civil Aeronautics Authority, is the same, namely, to know at all times the actual load condition of the aircraft. It is true, however, that the reasons for requiring this information differ as considered by the Authority and the air carrier.},

keywords = {03. Center Of Gravity},

pubstate = {published},

tppubtype = {inproceedings}

}