796. Effect of the Location of a Fixed Weight Penalty on the Aircraft Growth Factor

Paper

Abstract

The fixed weight growth factor as defined by Ballhaus required performance and handling qualities to be maintained for the growing airplane. By including two essential criterias – a constant static stability margin at the aft c.g. and the trim capability at the forward c.g. – into the design loop for constant performance the fixed weight growth factor becomes a function of the location of the primary weight penalty along the fuselage station. A computer aided design program is used to calculate the growth factor by repeating the iterational design process until certain aircraft characteristics have converged to a number within a given tolerance. The wing location is used for c.g. control using the static stability margin as the driving criteria. The horizontal tail size is determined by the forward c.g. trim requirement. Growth factor variation with fuselage station can be used to consider the effect of a moment on takeoff weight. For high performance fighter airplane the fixed weight growth factor can vary by a factor of two between the most forward and most aft fuselage station.