Maximum Takeoff Mass versus Number of Passengers

Figure 4.5 describes the relationship between passenger capacity and MTOM, which also depends on the mission range for carrying more fuel for longer ranges. In con­junction with Figure 4.4, it shows that lower-capacity aircraft generally have lower ranges (Figure 4.5a) and higher-capacity aircraft are intended for higher ranges (Figure 4.5b). Understandably, at lower ranges, the effect of fuel mass on MTOM is not shown as strongly as for longer ranges that require large amounts of fuel. There is no evidence of the square-cube law, as discussed in Section 3.20.1. It is possible for the aircraft size to grow, provided the supporting infrastructure is sufficient.

Figure 4.5 shows an excellent regression of the statistical data. It is unlikely that this trend will be much different in the near future. Considerable scientific break­throughs will be required to move from the existing pattern to better values. Light but economically viable material, superior engine fuel economy, and miniaturization of systems architecture are some of the areas in which substantial weight reduction is possible.

In conjunction with Figure 4.4, it can be seen that longer-range aircraft gener­ally have higher MTOM; estimates of MTOM per passenger are provided herein (Table 4.1). At the start of a conceptual study, the MTOM must be guessed – these statistics provide a reasonable estimate. Below 2,500 nm, the accuracy degenerates; the weight for in-between ranges is interpolated.

EXAMPLE: For a mission profile with 300 passengers and a 5,000-nm range, the MTOM is estimated at 750 x 300 = 225,000 kg (comparable to the Airbus 300-300).