One of the dominant parameters of longitudinal stability and control has been shown in the foregoing sections to be the fore-and-aft location of the CG (see Figs. 2.14, 2.18, 2.19, 2.25, 2.27, 2.28, and 3.2). The question now arises as to what range of CG position is consistent with satisfactory handling qualities. This is a critical design problem, and one of the most important aims of stability and control analysis is to provide the answer to it. Since aircraft always carry some disposable load (e. g., fuel, armaments), and since they are not always loaded identically to begin with (variations in passenger and cargo load), it is always necessary to cater for a variation in the CG position. The range to be provided for is kept to a minimum by proper loca
tion of the items of variable load, but still it often becomes a difficult matter to keep the handling qualities acceptable over the whole CG range. Sometimes the problem is not solved, and the airplane must be subjected to restrictions on the fore-and-aft distribution of its variable load when operating at part load.