**5. Comparison of SCA noise benefit at using reference and programmed TM**

The **Figure 7** shows the comparative acoustic efficiency of using the programmed take-off TM vs. reference take-off TM. Changes of the flyover noise in case of replace of reference with programmed take-off TM does not exceed 1 EPNdB that is associated with the same flight conditions above the flyover RP (see **Figure 4**).

The changes of the lateral noise level are equal to 2.6 to 6.1 EPNdB depending on BPR.

The increase of the noise reduction benefit as increasing BPR is connected with increasing the contribution of fan noise to the total engine noise as well as increasing the influence of engine throttling in the fan noise. As a result, the change of the take-off (lateral plus flyover) noise level using programmed take-off TM instead of the reference take-off TM is equal to 2.3…6.0 EPNdB, depending on the BPR.

The **Figure 8** shows the change of SBJ approach noise level deviation from the approach noise in case of using turbofan with BPR = 2.5 and angle θ = −3.0o depending on BPR.

The changes of the approach noise level in case of replace of reference with programmed approach TM may reach up to 8 EPNdB depending on glide slope angle θ.

The assessment shown the potential effectiveness of a programmed approach TM, which reduces the approach noise level due to higher glide slope angle and flight altitudes above the approach RP.

The use of higher glide slope angle may lead to a more complex approach and landing procedures and requires the mandatory use of an instrumental automatic landing system, which is currently applied to many subsonic jet aeroplanes.

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

**Figure 7.**

*The benefit of SCA lateral, flyover and total take-off (lateral plus flyover) noise levels from the use of programmed take-off TM depending on the engine bypass ratio BPR.*

#### **Figure 8.**

*The benefit of SCA approach noise levels from the use of programmed approach TM depending on the glide slope angle* θ *and the engine bypass ratio BPR.*

## **6. Conclusions**

In connection with the development of a new version of the ICAO international standard for the noise levels of SCA at certification points during the LTO cycle and the introduction of the USA national standard, it becomes relevant to study new opportunities to reduce the noise for such type of aircraft. The use of programmed thrust management (control) at the LTO cycle is evaluated in the paper as a tool for reducing the SCA noise levels. A comparative assessment of effective perceived noise levels in case of using the reference (conventional for subsonic jet aeroplanes) and programmed thrust management is applied to notional twin-engine supersonic business jet (with seating capacity of 8 pax, a range of 7 400 km, and the balanced field length of 2 000 m).

The following main results are obtained:


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

noise are equal to 2300, 4000 and 5800 m respectively. The optimal thrust throttling rates for transition on the power settings providing reduced lateral and flyover noise are 15 and 2.5% of thrust per minute respectively.

The study of programmed thrust management should be continued in the direction of taking into account the effect of noise shielding by airframe elements and the application of acoustic liners in the propulsion system.
