1466. Optimizing Tail Size and Wing Location Within Loadability Constraints
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Paper
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