**3. Mission performance assessment for the SBJ at fixed flight range and using of turbofan with different BPR**

The calculation of mission performance is performed for the SBJ with fixed flight range taking into account the flight segments like take-off, initial climb, climb, supersonic cruise, descent, approach, landing, and NBAA alternate. The engine size (and the corresponding SLS thrust and the take-off thrust loading) is defined from the balanced take-off condition and the given balanced field length BFL = 2000 m. At the definition of balanced field length the minimal one engine inoperative climb gradient at the altitude of 10.7 m is considered as the constraint [5].

Keeping the specified values of the flight range L, the seating capacity n and the balanced field length BFL with an increase of BPR leads to an increase of the maximum certificated take-off mass MTOM. It is primarily happened due to an increase of the required engine take-off thrust FNto and propulsion system mass Wps.

The **Figures 1** and **2** show the changes of MTOM (**Figure 1**), relative take-off thrust FNto\_rel and propulsion system mass Wps\_rel (**Figure 2**) depending on the BPR.

#### **Figure 1.**

*The change of maximum certificated take-off mass MTOM vs. engine bypass ratio BPR (L = 7400 km, n = 8 pax, BFL = 2000 m).*

*Estimation of Cumulative Noise Reduction at Certification Points for Supersonic Civil… DOI: http://dx.doi.org/10.5772/intechopen.97465*

The relative values of the take-off thrust FNto\_rel and the propulsion system mass Wps\_rel are equal to:

$$\text{FNto\\_rel} = \text{FN}\_{\text{to}} / \text{FN}\_{\text{to}\text{BPR}=2.5}, \text{Wps\\_rel} = \text{W}\_{\text{pa}} / \text{W}\_{\text{p}\text{BPR}=2.5}. \tag{1}$$

where FNto, FNto BPR = 2.5, Wps and Wps BPR = 2.5 are the take-off thrust and propulsion system mass for the turbofan with current BPR and BPR = 2.5 correspondingly.

It can be seen that as BPR changes from 2.5 to 5.0 with fixed values of L, n and BFL, the take-off thrust FNto and the propulsion system mass Wps increase by 57 and 90%, respectively, while the MTOM increases from 55 000 to 77 000 kg, i.e. on 40%.

A noticeable increase of the MTOM at highest BPR may lead to an increase of the direct operating cost, which could be economically unacceptable. Therefore, the cost efficiency of use of turbofan with the higher BPR should be evaluated in the future activities more detail.
