This paper evaluates the reduction of airport noise that can be expected from an optimized LH2-fueled SST due to its shorter takeoff and landing performance compared to an equivalent kerosene-fueled SST. An initial comparison shows that flyover noise is reduced by 7.7EPNdB since the LH2-fueled SST has a steeper climb following a shorter takeoff roll. Although sideline and approach noises are increased, the total cumulative loudness is reduced by 6.5EPNdB. Then, the effect of reduced-thrust takeoff is evaluated for the LH2-fueled SST, which has a takeoff performance surplus. The result shows the sideline noise is reduced while flyover noise is increased. A parametric study is also conducted for further airport noise reduction potential.
To predict harmful acoustic loading due to the intense acoustic waves generated by exhaust jets from propulsion systems of launch vehicles during lift-off, a numerical method based on computational fluid dynamics is developed. High-fidelity large-eddy simulations, or hybrid large-eddy and Reynolds-averaged Navier-Stokes simulations are employed for the computation of the hydrodynamic field. Computational aeroacoustic simulations based on full-Euler equations are applied to compute acoustic propagation to the farfield. Validation and verification studies are conducted using experimental results of free and impinging jets from a 2.4%-scale solid motor. It is found that the prediction accuracy with approximately 4 dB in overall sound-pressure level is obtained for both the free and impinging jets.
On-board orbit determination (OD) using a Sun sensor and optical navigation camera (ONC) for autonomous navigation (AutoNav) is discussed in this paper. In low-Earth orbits, a global positioning system (GPS) is used for AutoNav. On the other hand, in deep space, the OD has been performed using range and range-rate (RARR), which is a traditional ground-tracking approach applying radio waves. RARR enables OD to have higher accuracy compared to other methods. However, such radio navigation has inevitable problems, such as the delay of radio waves, reduction in radio-wave strength and transmitter limitations. The influence of these problems becomes significant, especially for deep-space missions. Furthermore, it requires ground station staff to operate the spacecraft with full attention, which increases the operational cost considerably. Therefore there has been a growing interest in the AutoNav of the spacecraft in recent years because AutoNav can eliminate the aforementioned problems. The utilization of the AutoNav in deep space can reduce the complexity of operation at the ground station, and especially has a significant impact on reducing operational cost. This paper focuses on the configuration of observation objects and the sampling frequency for observation. Finally, as an example, the selection of observation and Earth-resonant trajectory are discussed.
July 31, 2017 Due to the end of the Yahoo!JAPAN OpenID service, My J-STAGE will end the support of the following sign-in services with OpenID on August 26, 2017: -Sign-in with Yahoo!JAPAN ID -Sign-in with livedoor ID * After that, please sign-in with My J-STAGE ID.
July 03, 2017 There had been a service stop from Jul 2‚ 2017‚ 8:06 to Jul 2‚ 2017‚ 19:12(JST) (Jul 1‚ 2017‚ 23:06 to Jul 2‚ 2017‚ 10:12(UTC)) . The service has been back to normal.We apologize for any inconvenience this may cause you.
May 18, 2016 We have released “J-STAGE BETA site”.
May 01, 2015 Please note the "spoofing mail" that pretends to be J-STAGE.