%A GENG Jianzhong;WU Huzi;DUAN Zhuoyi %T Design Criteria for Variable Range of Gravity Center for a Large Subsonic Aircraft with Relaxed Static Stability %0 Journal Article %D 2013 %J Science & Technology Review %R 10.3981/j.issn.1000-7857.2013.h1.013 %P 67-71 %V 31 %N 5-6 %U {http://www.kjdb.org/CN/abstract/article_10129.shtml} %8 2013-02-28 %X The controls of the traditional natural stable subsonic large aircraft and the modern subsonic large aircraft with relaxed static stability are analyzed. The design criteria for variable range of the allowable center of gravity are proposed based on demands for the subsonic large aircraft with relaxed static stability and various influencing factors. The relation formulas under different influencing factors between the relative horizontal tail area and the center of gravity are obtained. The curve of the center of gravity against the relative horizontal tail area is found to be different from the traditional "scissors figure". If the relative horizontal tail area is given, the scope of the center of gravity can be easily determined. To illustrate the feasibility and the reliability of the proposed design standards, a verification calculation is carried out based on a special plane. Through the analysis of the calculation results, the main factors that influence the design of the scope of the center of gravity are obtain, including the initial rotation and the taxi stability. The optimum performance of the center of gravity can be fully used in adjusting the landing gear position and the design cruising speed.