# Bizjet Aircraft CG Location Example

Table 8.7 and Equations 8.54 and 8.55 are used to locate the CG. SI units are used.

Both the mass and the CG location are slightly different than the preliminary data. This results in the CG angle, в = tan-1 (8.4 -7.44)/1.357 = tan-1 0.7 = 35 deg. This is a satisfactory angle to cover the maximum fuselage-rotation angle at takeoff.

The CG is located almost at the middle of the baseline aircraft length, and the wing is positioned just behind it, which indicates that the CG is in the forward posi­tion. Proper CG positioning can be established after the aircraft neutral point is determined; the forward and aft CG limits can be ascertained by fine-tuning the

Table 8.7. Determination ofBizjet CG location

 Item Group Mass (kg) X(m) Moment Z(m) Moment Fuselage 930 6.8 4,284 1.6 1,488 Wing 864 7.8 6,739.2 1 864 H-tail 124 14 1,736 8 992 V-tail 63 15 945 3 189 Undercarriage (nose) 110 1.2 132 0.4 44 Undercarriage (main) 270 8.4 2,268 0.5 135 Nacelle/pylon 212 10.2 2,346 2.1 460 Miscellaneous Power plant 1,060 11 11,660 1.9 2,014 Systems 1,045 6.5 6,792.5 1 1,045 Furnishing 618 6 3,708 2 1,236 Contingencies 143 3 429 1.2 171.6 MEM 5,457 Crew 180 3 540 1.4 252 Consumable 119 4.25 505 1.5 152 OEM 5,800 Payload 1,100 6 6,600 1.1 1,210 Fuel 2,500 8.5 21,250 1 2,500 Total moment at MTOM 9,400 69,934.7 x = 7.44 m 12,752.6 z = 1.357 m MRM 9,450

component positions. Determining the aircraft neutral point is not addressed in this book, but it is approximately 50 to 55% of the wing MAC. Therefore, in this case, only small changes may be required to fine-tune the aircraft CG limits. Changing the wing position may be problematic, but a small degree of engine repositioning can be effective. Relocating heavy onboard items is easy and effective for last-minute fine – tuning, especially during flight-testing.