SAWE Technical Papers

@inproceedings{3659,

title = {3659. Weight and CG Curtailment},

author = {Patrick Brown},

url = {https://www.sawe.org/product/paper-3659},

year  = {2016},

date = {2016-05-01},

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

pages = {10},

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

address = {Denver, Colorado},

abstract = {Without fail, weight and center of gravity (CG) change during every aircraft flight. In some aircraft, especially large passenger aircraft, the ability to safely account for weight and CG movement during flight can become problematic. There are unknown passenger and cargo weights. The crew and passengers often move large distances in the cabin and the cargo CG can shift unexpectedly during flight. Angle of attack and fuel burn often create CG movements due to fuel migration. The complexity of the analysis is large and the risk of failure is enormous. Any one or combination of those events in flight can be catastrophic. However, the risk to crew, passengers, cargo and aircraft can be mitigated by the proper use of weight and CG curtailment. In fact, by applying proper weight and CG curtailment methods during flight planning, those risks can be entirely eliminated as a cause of incident, accident, or catastrophic failure. The only other possible way of eliminating those risks would be to know the weight and CG of every crewman, passenger, cargo, and gallon of fuel and completely limit their movement. Or, better yet, develop a 'smart' plane that senses CG movement and automatically compensates for it during flight. As yet, that technology does not exist, is too costly and or complex to implement in a commercial aircraft environment. Weight and CG curtailment uses quantitative methods to shrink the flight envelope so that every likely shift in weight and CG is accounted for in the given flight profile or mission. In fact, as the only viable solution, every large aircraft operator uses weight and CG curtailment in one form or another to dispatch their aircraft in a safe and timely manner.},

keywords = {01. Aircraft Loading - General, 17. Weight Engineering - Procedures},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3313,

title = {3313. Engineering Guidelines for Tungsten Heavy Alloy Counterweights},

author = {Steven Caldwell},

url = {https://www.sawe.org/product/paper-3313},

year  = {2003},

date = {2003-05-01},

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

pages = {14},

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

address = {New Haven, Connecticut},

abstract = {For both fixed and rotary wing aircraft, there are needs for concentrated mass to either balance gravitational forces or provide inertial damping of specific mechanisms. Several high-density materials have been used historically in such applications, but the continued use of some now falls into question on the basis of associated environmental and/or occupational safety issues. 

Tungsten heavy alloys (WHAs) offer a unique combination of high density, good mechanical properties, easy machinability, and low life cycle cost in addition to low toxicity. As a consequence, they are the ideal materials for counterbalance weight applications. While composed of common metals, WHAs are a unique family of engineering alloys for which material properties and design information are generally difficult to locate, as they are listed in few reference texts. This presentation provides basic design and metallurgical considerations for the use of this family of materials in a variety of aerospace applications. Important engineering aspects such as elevated temperature implications, mechanical strength requirements, joining considerations, and corrosion protection are addressed. Additionally, as WHA components are fabricated by the powder metallurgy process of liquid phase sintering, special design guidelines should be followed for obtaining optimal performance of these metal matrix composite materials. Examples are also presented that illustrate how larger assemblies can be constructed and yet circumvent the size and shape limitations of the liquid phase sintering process for individual components. 

These data are presented to assist the mass properties designer with information specific to WHAs for better utilization of material properties and weight integration options for aircraft systems. WHAs allow the design of space efficient, environmentally friendly aviation counterweights for both new vehicles and the retrofit of existing craft to comply with increased regulatory constraints for toxic metals.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3019,

title = {3019. Microsoft Excel Applications for Airliner Weight & Balance},

author = {Tom Farncombe},

url = {https://www.sawe.org/product/paper-3019},

year  = {2000},

date = {2000-06-01},

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

pages = {19},

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

address = {St. Louis, Missouri},

abstract = {Spreadsheet applications can provide many software solutions to the weight and balance engineering processes of an airline. It is possible to couple individual applications to evolve larger and more comprehensive software solutions without the need for extensive programming knowledge or experience. Individual tasks within the Qantas Airways weights engineering department were gradually migrated to spreadsheets, leading to the beginnings of simple applications such as weighing result calculation and weight growth surveillance. It became apparent that there was duplication of data stored within individual applications that could be minimized by linking individual spreadsheets to common data files. The core data for each aircraft type was written into spreadsheet files, formatted to replicate the IATA AHMSO report, the document used by IATA member airlines as a standard for the transmission of base weight and balance data between airline I.T. departments. From these files, other spreadsheets were programmed to receive core data for manipulation into other specific tasks such as the production of charts and operational weight certificates. 

With all core data stored in a structured format, development tasks were simplified as specific tables could be easily located and identified. Mini applications were developed to enable access to files, by adding additional menus to the spreadsheet application environment. Visual Basic interfaces were developed to assist the user in finding and opening specific spreadsheets by following on-screen prompts such as ?Enter Aircraft Type...? and ?Enter Aircraft Registration...? Date checking functionality was also built into the environment to address expiry dates of operational documentation such as weight certificates, which are issued for a defined time period. Prompts were designed to draw the user to certain data when an expiry date was close. 

Refining the existing spreadsheets was an ongoing process and with the introduction of a new Mainframe Departure Control System, a requirement emerged to develop a testing environment to facilitate regulatory approval of the new system. With the knowledge gained from working inside the Departure Control System, and an understanding of the limitations of spreadsheet capabilities, a full working model of a departure control system was evolved. The working model was then improved to a level of reliability suitable for release into the live load control environment itself. Other small applications were also investigated to determine the benefit of developing small applications to run in parallel to the Departure Control System. 

This paper discusses three projects undertaken using spreadsheet applications for I. T. solutions.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2450,

title = {2450. AIRBUS A340 Weight and Balance System},

author = {U Kehlenbeck},

url = {https://www.sawe.org/product/paper-2450},

year  = {1999},

date = {1999-05-01},

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

pages = {16},

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

address = {San Jose, California},

abstract = {For take-off and flight planning pilots require the actual gross weight and the centre of gravity of an aircraft. A so called Weight and Balance System (WBS) has been certified in 1993 for all AIRBUS A330/A340 aircraft types. It is an on-board system which measures Gross Weight (GW) and Centre of Gravity (CG) on-ground and displays these values in real-time in the cockpit. Over a period of 5 years the WBS has proven that the achieved accuracy, reliability and robustness are far better than certified. Airlines are aware of a useful system for independently cross-check the load and trim sheet (LTS) manifest with an accuracy better than 1% of the actual aircraft weight. During development and certification tests and within a two years In-Service-monitoring phase at one customer the AIRBUS WBS has been tested in any kind of external influences to an aircraft (e.g. wind, torsion, temperatures, hard turns). Heart of system are 32 inductive sensors mounted on lugs at different locations at the landing gears. Due to the extremely high sensitivity of these sensors (working area 10_m under full load) careful installation, adjustment and a complex system calibration is required. For future aircraft programs the existing system should be improved to include some more specific functions related to the landing gears. It is very likely that ?hard landing detection? or ?landing gear monitoring? function could be included as well as new types of sensors could be found. Within a European research project it shall be demonstrated that the magnetic Barkhausen noise (known from the non-destructive testing - NDT) can be used to measure the actual weight of an on-ground aircraft in real-time. Extensive laboratory testing have to be carried out to discover the accuracy, reliability and robustness of Barkhausen Noise Sensors operating in the harsh environment of aircraft landing gears. The compensation of external influences and parameters on the micromagnetic effect is one of the challenges. Basis of the expected results is the extremely high and reproducible sensitivity of Barkhausen Noise to the stress and strain variations in the loaded components of the aircraft under weight increments. This technical paper is describing the development of the current AIRBUS WBS as well as future system developments in relation to additional functions and the use of new sensor types.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2437,

title = {2437. Weight and Balance in the Airline Operation},

author = {J S Frimer},

url = {https://www.sawe.org/product/paper-2437},

year  = {1998},

date = {1998-05-01},

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

pages = {47},

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

address = {Wichita, Kansas},

abstract = {The weight and balance role in airline operations is an important role that is not always given the attention and dedication it requires. Federal Aviation Regulations require control of weight and balance for all air operations. In many parts of the developing world, an extensive program for control of weight and balance has been implemented, but, as will be shown, there still remains plenty of opportunity for improvement. This paper provides the reader an orientation to the role of the Flight Operations department in ensuring weight and balance is carefully controlled, and the mission is safely carried out.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2278,

title = {2278. Real Time Related Dry Operating Weight System},

author = {E R Galjaard},

url = {https://www.sawe.org/product/paper-2278},

year  = {1995},

date = {1995-05-01},

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

pages = {30},

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

address = {Huntsville, Alabama},

abstract = {A major concern of airlines is weight saving. Each extra kilogram (pound) on an aircraft Basic Weight costs fuel and may not be used for payload. In the 1970s when fuel prices soared, within KLM it was decided to organize a Weight Saving Committee. The committee was composed of members from the following departments: Technical/Engineering, Flight Operations, Performance, Ground Handling, Catering/Inflight Services, and Cabin Crew. During Weight Saving Committee sessions most of the weight savings were obtained on the aircraft Basic Empty Weight (BEW), in the form of light weight inplane loading systems, removal of permanent technical flight kits, installation of light weight floor panels, tires, etc. KLM is a so-called Dry Operating Weight (DOW) carrier. A DOW can be calculated for a group of aircraft in the same weight range, a so called fleet weight or a DOW for each individual aircraft. Within KLM for each flight a DOW and Dry Operating Index (DOI) was calculated based on maximum weights for Pantry and Potable Drinking Water. It was realized that further weight savings could be made in the DOW by controlling the uplift of potable water and catering to match the number of passengers carried. The weight reduction will result in a fuel saving and would enable us to carry additional payload. Naturally this will require additional fuel to carry the extra payload. It was calculate that this would result in an annual profit of about 6 million Dutch guilders (US $4 million). For this reason in 1992 a working group started to develop a Dry Operating Weight System which would calculate the ?Real Time Related? Dry Operating Weight and Index for each individual flight. As from Spring 1994 the Dry Operating Weight System was gradually introduced in the KLM network for flights operating with Boeing 747-400 and MD-11 aircraft which are equipped with a potable water preselect system. Other aircraft types in the KLM fleet are not equipped with a potable water preselect system (Boeing 747-300, Boeing 737, and Fokker 100). Based on the experience with the B747-400 and MD-11 fleet it will be decided if it is worthwhile to equip all aircraft in the KLM fleet with a potable water preselect system. The Dry Operating Weight and Dry operating Index (DOW/DOI) can be retrieved from the DOW System with a request message. The main purpose of the DOW System is to release the actual calculated DOW/DOI data to the station which made the request based on the actual number of crew and the weight for potable water and pantry based on the actual number of booked passengers.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2162,

title = {2162. Basic Principles of Weight and Balance},

author = {G L Marion},

url = {https://www.sawe.org/product/paper-2162},

year  = {1993},

date = {1993-05-01},

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

pages = {9},

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

address = {Biloxi, Mississippi},

abstract = {Knowledge of the basic principles of weight and balance will lead to better understanding of aircraft loading. This should allow for the control of the Center of Gravity (CG) within the aircraft' s safe loading range. Controlling the CG within the safe loading range will have an effect on the pitching moment of the aircraft and thus an effect on induced drag. Effecting induced drag is relative to thrust setting and fuel burn. Shifting the CG as far aft as possible in the safe loading range could see reductions in fuel consumption ranging from ,05% to .2% for each percent mean aerodynamic chord (MAC) shift aft. Although the percentages may be small they are significant when considering total fleet fuel.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{2166,

title = {2166. KLM's Passenger Weighing Survey},

author = {E R Galjaard},

url = {https://www.sawe.org/product/paper-2166},

year  = {1993},

date = {1993-05-01},

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

pages = {39},

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

address = {Biloxi, Mississippi},

abstract = {The reappraisal of the standard passenger weights currently in use in Europe was prompted by a Joint Aviation Requirement (JAR) issued by the Joint Aviation Authorities (JAA). The JAA, which developed by informal collaboration among European civil aviation authorities in the 1970s, has been officially recognized by the European Civil Aviation Conference (ECAC) since 1989. Since this date, the development, approval, and introduction of JARs has been regulated at an international level. Any ECAC state may join the JAA by ratifying these regulations. The interest of the various air carriers in Europe is represented in the JAA and its working groups and committees by the Association of European Airlines. The main section of JAR OPS 1-4,097, ''Mass values for passenger and baggage,'' contains standard weights to be used for weight calculation on loadsheets. Standard passenger weights vary according to the number of seats with which an plane is equipped. On an plane with more than 30 seats, for example, a standard weight of 84 kg (185 lb) for adult passengers should be used, This figure is higher than those currently used by most European carriers. However, JAR-OPS 1-4.097 also offers member states the option of using different standard weights from those prescribed, provided their accuracy and validity can be proved. KLM Royal Dutch Airlines has made use of this option, in association with the Dutch Civil Aviation Authority. Furthermore, the survey was conducted on request by the JAA standard weights study group. The survey results will be used by this group to obtain representative weights for the final JAA regulation. This paper presents the results of the passenger weighing survey performed by KLM in relation to the J AR OPS Furthermore, it presents the research to the most economical passenger weights related to payload.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1986,

title = {1986. Weight and Accountability - an Airline Point of View},

author = {G Marion},

url = {https://www.sawe.org/product/paper-1986},

year  = {1991},

date = {1991-05-01},

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

pages = {16},

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

address = {San Diego, California},

abstract = {The certified weight and center of gravity (C.G.) limitations define the envelope of weight and C.G.'s that an airplane may be flown. Governmental air regulatory agencies require a check of the aircraft's weight and C.G. prior to takeoff to insure the aircraft is within these limits. Airline operators not only want to he safely within the limits, but also want to fly the airplane efficiently. Airlines preplan the airplane loading to most efficiently use the airplane within these limitations. Historically, the preplanning and the final weight and C.G. check have been accomplished with some type of a hand manifest. Estimated weights and C.G.'s of passengers, cargo, fuel, and operating items are added to a basic aircraft weight and C.G. Some hand manifests are computerized, but all manifests require the operation to input the aircraft basic weight, plus the passengers, cargo, fuel, and operational items. Weighing equipment which could be mounted on the aircraft was developed in the late 1960s. These ''Onboard Weight and Balance Systems'' as they are commonly referred to, use sensors to measure gear loads. These sensors are linked to a computer which calculates the weight and C.G. System manufacturers have proposed the use of onboard weight and balance systems to eliminate the hand manifest final weight and balance checks. In order to do this, the system must be accurate, reliable, and most of all, economical. This paper attempts to explain basic weight and balance, presents an insight into how it occurs for an airline operation, and ends with a view of onboard weight and balance systems as they exist today.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1959,

title = {1959. Check Sheet for Structural Loading Limitations - Boing 747-Combi Aircraft},

author = {E R Galjaard},

url = {https://www.sawe.org/product/paper-1959},

year  = {1990},

date = {1990-05-01},

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

pages = {13},

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

address = {Chandler, Arizona},

abstract = {Accurate checks for structural loading limitations are required for every commercial aircraft flight to ensure that the certified structural loading limitations of an aircraft are not exceeded. The Weight and Balance manual is the authority that specifies the allowable limits on aircraft loading. The data contained in this manual reflects the design limits established by the aircraft manufacturer and approved by the aviation regulatory authorities. The techniques used by the manufacturer to present and publish these limits in their manuals usually preclude direct use in the operational environment. The data published is general and not related to a specific aircraft passenger/ULD (Unit Load Device) configuration. The configuration is decided by the airline and may differ by aircraft/flight The purpose of this paper is to familiarize the audience with the basic principles of structural loading limitations and the ''check sheet for structural loading limitations'' for the Boeing 747 COMBI aircraft in use at KLM.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1964,

title = {1964. Trends in Standard Passenger Weight},

author = {D R Banes},

url = {https://www.sawe.org/product/paper-1964},

year  = {1990},

date = {1990-05-01},

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

pages = {48},

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

address = {Chandler, Arizona},

abstract = {In May of 1983, the Society of Allied Weight Engineers (SAWE) was asked by the International Air Transport Association (IATA) for assistance in updating IATA's guidelines concerning standard passenger and baggage weights. This paper contains a summary of the study performed by SAWE and IATA's revised guidelines pertaining to standard passenger and baggage weights. The standard passenger weight is the weight assigned to every passenger, regardless of their actual weight, for the purpose of determining the total passenger load on the airplane. The standard passenger weight is derived by statistically analyzing surveys of actual passenger weights. The IATA guidelines provide a standard passenger weight suitable for most carriers and recommended procedures for establishing standard passenger weights for airlines wishing to determine their own standard weight. The SAWE study was conducted at the 1984, 1985, and 1986 SAWE International Conferences in the Government/Industry Session. This paper presents the effects of population weight trends and changes in the ratio of men to women passengers of the standard passenger weight. It will also give some possible reasons for changes in standard passenger weights. Included is an example of the effects a change in the standard passenger weight would have on the loading characteristics of a midsize airliner.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1895,

title = {1895. Effects of External Loads on Onboard Weight and Balance System},

author = {M L Nolan},

url = {https://www.sawe.org/product/paper-1895},

year  = {1989},

date = {1989-05-01},

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

pages = {22},

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

address = {Alexandria, Virginia},

abstract = {Accurate weight and center of gravity (cg) checks are required for every commercial aircraft flight to insure the certified weight and center of gravity limits of an airplane are not exceeded. The hand manifest and the onboard weight and balance system are two current methods available to accomplish these checks. The hand manifest is the most common method. It determines the airplane weight and cg by adding estimated weights and cg's of the passengers, cargo, fuel, and operational items to a known empty airplane weight and cg. The onboard weight and balance system automates this task and provides a more accurate weight and cg. It is a computer link with load measuring sensors which can weigh the fully loaded airplane just prior to takeoff in a typical airport environment. The onboard weight and balance system is subject to some uncertainties. These include the load sensing equipment tolerances and external loads. External loads that may be read by the load sensors include effects of wind, ice, rain, snow, and asymmetrical gear loads. The classical method of accounting for uncertainties like these is to place restrictions on the cg range of the certified limits. This paper attempts to account for the uncertainties caused by the external loads and to compare these to typical uncertainties of the hand manifest system. The magnitude of each external load is determined. CG restrictions are developed to account for these external loads and compared to the typical cg restrictions of the more common hand manifest system. The external load effects on a large and small commercial airplane are addressed.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1824,

title = {1824. MH-53E Flight Performance Computer},

author = {R Gilliam and A Billings},

url = {https://www.sawe.org/product/paper-1824},

year  = {1988},

date = {1988-05-01},

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

pages = {36},

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

address = {Plymouth, Michigan},

abstract = {This paper briefly reviews the evolution of VTOL performance/weight and balance computation devices, from charts and graphs through hand held load adjusters, performance slide rule calculators, and on-board electronic devices. The newly developed MH-53E missions and flight performance computers and their capabilities are discussed in detail. Horizon Technology Corporation capabilities and developments in this area are presented and the potential capabilities of the next generation VTOL performance computer systems are discussed.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1840,

title = {1840. Lodability Consideration in Preliminary Design},

author = {P Scott},

url = {https://www.sawe.org/product/paper-1840},

year  = {1988},

date = {1988-05-01},

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

pages = {20},

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

address = {Plymouth, Michigan},

abstract = {Loadability (i.e., flexibility in accommodating various payloads without exceeding volume or center of gravity limitations) is analyzed for military cargo aircraft. A loadability parameter is defined to permit comparison between military cargo transports and to aid preliminary tail sizing. This parameter is the acceptable payload CG range for the maximum 2.5 g payload as a percentage of the flat cargo floor length. A significant increase in this parameter from the C-130 to the C-5 to the C-17 is documented. It is projected that the demanding operational requirements of the Advanced Tactical Transport (ATT) will further increase the magnitude of the loadability parameter. The weight-versus-loadability tradeoff is investigated for both STOL and VSTOL ATT configurations. Perhaps the most significant aspect of the loadability parameter is its usefulness for tail sizing. The loadability parameter may be used directly in determining tail size, thus enabling trade studies to be performed for equal loadability between competing configurations.},

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

keywords = {01. Aircraft Loading - General, Mike Hackney Best Paper Award},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1466,

title = {1466. Optimizing Tail Size and Wing Location Within Loadability Constraints},

author = {W B Tutor and D R Busch and D P Marsh},

url = {https://www.sawe.org/product/paper-1466},

year  = {1982},

date = {1982-05-01},

booktitle = {41st Annual Conference, San Jose, California, May 17-19},

pages = {22},

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

address = {San Jose, California},

abstract = {The determination of center of gravity (CG) limits for transport aircraft is a subject that interests not only the project weight engineer, but also the loadmasters and operational weight engineers who represent airlines and the military. The size of the horizontal tail area determines the CG range, and the wing location determines the position of the payload envelope within this range. This paper discusses the problem of determining CG limits, with special emphasis on selecting the optimum wing location and tail size for new or derivative aircraft, to ensure safe and economical operation while maintaining the required load ability characteristics. 

Methods are discussed that use functional/geographical mass distribution fractions, center-of-gravity factors, loading limits from 'scissor plots,' and computer-generated loading diagram. A procedure to balance an aircraft is described, including an outline of the necessary data base information required to perform the calculations, as well as a definition of the tools required to actually perform a balance analysis. This technique allows experienced engineers to find optimum solutions quite rapidly by having computers perform the multitude of tedious and repetitive calculations; the engineers visually monitor the process and the results. The ability to rapidly balance advanced-design aircraft is also important in candidate selection studies where several configurations have to be analyzed. For example, an all-cargo and a passenger-transport balance analysis are traced, showing the different techniques required to satisfy each condition. 

The interaction between the various parameters involved in the analysis are discussed, showing that a change in any one of the parametric values has a ripple effect on all of the other parameters, causing a direct, one-pass approach to the solution to be virtually impossible. 

Economic trades are also discussed, specifically the trade off between tail area and cruise CG position to find a minimum-fuel-usage solution},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1470,

title = {1470. Philosophy of Automated Balance Calculations},

author = {J R McCarty},

url = {https://www.sawe.org/product/paper-1470},

year  = {1982},

date = {1982-05-01},

booktitle = {41st Annual Conference, San Jose, California, May 17-19},

pages = {15},

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

address = {San Jose, California},

abstract = {It is the intent of this paper to outline the philosophy, or methodology, developed and used by United Airlines to evaluate and control the balance aspects of a trip departure using a real time computer program. 

As large computers become available and have been used for all kinds of data storage and processing in real time in the airline industry, the idea of using them for weight and balance control has been considered. Any numbers of airlines have already implemented programs to perform this function to their satisfaction. United is somewhat of a late comer largely because it proved difficult for us to justify the cost of automating, at last, its time has come. 

We have had limited discussions with other operators as to their automated systems. Much of the feedback has been second or third hand and so leaves open questions. In total, we have been unsuccessful in getting concrete information on how other operations perform their task either because our contact did not know or would not say. There is a general impression that the equivalent of the old tabular loading chart, max-min in a controlling cargo pit, is calculated and then stored in the computer as a look-up table. Computer people seem to view method as the easiest and least expensive approach. 

At the inception of the specification writing for our automated balance control program, we knew how we wanted to do the job so the effort to learn about the programs was perhaps somewhat academic and largely a reflection of the natural desire to have one's concepts confirmed or vindicated. 

In summary our philosophy is to have the computer do a complete calculation or analysis for each change in loading in order to exploit the loading flexibility as much as possible. This means that we consider the exact passenger count, the exact cargo load, and the exact fuel load - takeoff through burnout. These combinations are measured against the CG limits and related balance variations for the three operating modes of takeoff, enroute and landing to evaluate the critical or controlling case for the flight. 

The methodology for performing this task is our so called 'Protective Level Concept' of balance control, a statistically based method that measures the variability of all load items in order to arrive at a level of CG limit protection directly related to the passenger/cargo/fuel combination that exists on this trip today. 

As an example, the curve representing the familiar passenger seating, window-aisle concept envelop, at a defined one sigma level, is reduced to a polynomial and the coefficients stored in the data base. In this form, the computer program can process it for any passenger count in that class or cabin zone. 

All of the statistical data is combined statistically, square root of the sum of the squares, set at the number of standard deviation defined as adequate, and added to any non-statistical variables, such as landing gear retraction, to arrive at the CG limit protective value. We can then calculate the cargo distribution to satisfy this restricted limit condition. At the same time, the takeoff CG position, %MAC, based on mean weight/moment condition can be calculated. 

This obviously is the point, that as a number cruncher the computer can repetitively process a large amount of detailed data very rapidly and thus exploit the airplane.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1401,

title = {1401. An FAA Approved, Simplified Method for Determining, Recording and Controlling Aircraft Weight, Loading and Balance in Ligh},

author = {E I Miller},

url = {https://www.sawe.org/product/paper-1401},

year  = {1981},

date = {1981-05-01},

booktitle = {40th Annual Conference, Dayton, Ohio, May 4-7},

pages = {28},

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

address = {Dayton, Ohio},

abstract = {At the present time, due to certain changes in the FAA regulations (FAR's) operators of airplanes in the 'light aircraft' category are now required to meet virtually the same requirements for their commuter and charter operations as those in the 'heavy wagon' class. Corporate aircraft, who often for financial tax and insurance advantages, choose to conduct their flight operations as an FAA approved charter business must also meet these requirements. This paper reviews these requirements and regulations, discusses the reasons (and reasoning) behind FAA's changes, and why they have had such an impact of light aircraft operations. It suggests a method similar to that used by the large commercial airline operations which can be easily adapted for use by light aircraft without changing any of the material or methods outlined in current ops manuals or FAA regulations, will lessen this impact and provide a quick, simple and accurate method of meeting all requirements.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1405,

title = {1405. Aft Index - A Normalized C.G. Envelope to Aid Computer Load Planning},

author = {R D Maxwell},

url = {https://www.sawe.org/product/paper-1405},

year  = {1981},

date = {1981-05-01},

booktitle = {40th Annual Conference, Dayton, Ohio, May 4-7},

pages = {13},

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

address = {Dayton, Ohio},

abstract = {A real time computer aircraft load planning system has been developed and put into service by Delta Air Lines. The most notable aspect of this system is the use of a C.G. envelope which has been normalized so the forward limit is zero and the aft limit is 100 on a scale designated as 'aft index.' The computer takes into account both the takeoff weight and zero fuel weight C.G. limits. The aft index is thus a 0 to 100 measure of how far aft (but within the envelope) the aircraft is loaded. It gives in one number the relationship of the aircraft C.G. to the allowable limits (which otherwise requires six numbers), and emphasizes the importance of aft loading for fuel economy. Although the internal computer calculations are relatively complex, the load planning function has been simplified for the user. Calculation routines are available to suggest a cargo distribution to achieve a desired aft index with a given passenger, fuel, and total cargo load.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1408,

title = {1408. United Designed System for Weighing Wide-Body Aircraft},

author = {J R McCarty},

url = {https://www.sawe.org/product/paper-1408},

year  = {1981},

date = {1981-05-01},

booktitle = {40th Annual Conference, Dayton, Ohio, May 4-7},

pages = {12},

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

address = {Dayton, Ohio},

abstract = {SAWE Paper 898, presented in 1971 outlined the development of a tripod jack fixture and a short stroke jack which permitted the load cell weighing of an airplane without removing the airplane from its jacked position. This was categorized as 'weighing in place'. The same philosophy was desired to weigh the wide-body airplanes but difficulties were encountered with vendor equipment. The result was again an in-house design of a tripod jack fixture which seems to do the job very well. Downtime of about 10 minutes to accomplish the actual weighing is achieved.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1338,

title = {1338. Operational Responses to Aft Empty C. G.},

author = {J R McCarty},

url = {https://www.sawe.org/product/paper-1338},

year  = {1980},

date = {1980-05-01},

booktitle = {39th Annual Conference, St. Louis, Missouri, May 12-14},

pages = {18},

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

address = {St. Louis, Missouri},

abstract = {When the 727-200 series, herein referred to as the Stretched airplane, came on the United Airlines scene in 1968, it became apparent that a ground handling problem of a magnitude not previously encountered was with us. 

The sequence of events appear to be as follows: 

A. An existing tail mounted engine design was stretched. 

B. Since the centroid of the cabin and pits in this design is forward, the Stretched airplane is more tail heavy when empty and tends to be more nose heavy when loaded for flight, compared to the standard or -100 airplane. 

C. Geometry, or location, of the main landing gear was unchanged. 

There was no particular problem with the loaded airplane, even in ferry flight operation, since compliance with the aft CG limits and the normal landing fuel load produced acceptable, or at least unreported difficulties with nose wheel steering for taxi-in. 

Off loading/loading of the airplane at the gate was protected by the requirements that the aft airstair must be down and locked before the airplane could be worked. The same rule applies to the case where maintenance is being accomplished. 

The problems lay in the case where the empty or maintenance airplane was being towed or taxied and in the overnight airplane where it was necessary to park the airplane, aft airstair up, for security purposes. This was addressed by imposing a minimum normally distributed fuel load or fuel distribution requirements that would load the nose wheel. 

The so called Advanced 727-200 airplane, which United Airlines began to receive in late 1977, worsened the situation. Further development of the design had produced the following changes. 

A. -15 engines with soundproofing and quiet nacelles added approximately 1000 pounds at the back end. 

B. Redesign in order to minimize weight growth results in a more tail heavy airplane since the weight removed tends to be at cabin centroid, forward of the main landing gear. 

The net effect was that the empty CG of the Advanced airplane is some 3 to 4 inches further aft than the Stretched airplane. The ballast required to get inside the aft CG limit in ferry flight operation and the minimum fuel required for ground handling is discouraging. Where we had apparently learned to live with the Stretched airplane, the dam burst when the requirements of the Advanced airplane became known in the field. 

A new problem arose in that the Flight Department now began to complain about the taxi-in characteristics of the airplane, particularly under slippery runway conditions. Ramp personnel also stated that towing-in was difficult at some tow-in gate positions due to nontracking of the nose wheel. 

Out of all of this grew procedures to routinely utilize 'payload fuel' and/or what was then called 'landing fuel credit' in ferry flight operation. Additionally, a ground CG limit was introduced, more restrictive than the aft flight CG limit, to force load on the nose wheel and further increase the ballast requirements. Evolution of terminology, coordination between departments, and training were initial problems, that seem to have been essentially resolved with time.},

keywords = {01. Aircraft Loading - General},

pubstate = {published},

tppubtype = {inproceedings}

}