LEMAC = station 144 CG – LEMAC = Distance from LEMAC 161" – 144" = 17" CG = 161" MAC = 206 – 144 = 62 In order to find the percent MAC, firs determine the distance  of the CG from LEMAC. Determine the location of the CG in inches from the datum  by using the formula found in  Figure 3-19 . The CG of this airplane is located at station 160.9 inches aft  of the datum. It is important for longitudinal stability that the  CG be located ahead of the center of lift of a wing. Since the  center of lift is expressed as percent MAC, the location of  the CG is expressed in the same terms. The location of the CG expressed in percent MAC is  determined using the formula found in  Figure 3-18 . The CG  of the airplane is located at 27.4 percent MAC. It is sometimes necessary to determine the location of the  CG in inches from the datum when its location in percent  MAC is known. The CG of the airplane is located at 27.4 percent MAC. Figure 3-18.  Formula for determining the CG expressed in percent  MAC. Figure 3-19.  Formula for determining the CG in inches from the  datum. Figure 3-17.  Largeaircraftweightand balancecalculationdiagram. CG = 27.4% CG = 161 MAC TEMAC LEMAC Datum CG CG  1 = 1 61 1 Station 144" Station 206" CG inches from datum = LEMAC +  MAC × CG % MAC 100 = 144 +  = 160.9 62 × 27.4 100 CG inches % MAC =  Distance aft of LEMAC × 100 MAC = = 27.4 17 × 100 62 3-9