JAXA's S4 Supersonic Low-Boom Airliner – A Collaborative Study on Aircraft Design, Sonic Boom Simulation, and Market Prospects

Abstract

In this work, the design methodologies and technical rationales for the design of JAXA's low-boom S4 (System integration of Silent SuperSonic airplane technologies) airliner are detailed with a focus on aerodynamic engine-airframe integration with respect to efficiency and sonic-boom abatement, respectively. The approach to high-fidelity CFD grid generation, flow simulation, and signature propagation for sonic boom assessment is explained, resulting in sonic-boom data maps with respect to flight physics parameters. Thereafter, DLR inserts the aircraft in operational scenarios for supersonic overland prohibition and permission, respectively, based on forecasted origin-destination passenger demand. Overwater flight routes are designed for the restrictive scenario, and the S4's flight performance data are used to simulate flight missions on all routes, yielding flight durations. Eventually, the respective market sizes for S4-type airliners are estimated and discussed.

Supersonic Overland Without a Sonic Boom – Quantifying the Speed Advantage of Mach-Cutoff Flight

“…Finally, the SuperTraC simulation scheme for overland Mach-cutoff flight can be described in short as follows: An altitude buffer over ground is selected that the sonic boom is never allowed to transgress, namely the cutoff altitude. Cruise segments are flown on isobaric flight levels 7 . Test ray tracings are performed on the targeted flight level over a certain forward distance in adequately small distance steps in order to determine the cutoff Mach number.…”

“…Eight supposedly representative intra-continental, inter-metropolitan city pairs of considerable distance and thus, most relevant for Mach-cutoff flight missions, were chosen for assessment (see Table 1 and Figure 4). Two supersonic aircraft designs were considered: JAXA's S4 airliner (version 1.3.4 [7], see Figure 5) whose flight performance data were provided by JAXA, and the HISAC-A supersonic business jet leadingly designed by Dassault [8] (see Figure 6) whose flight performance data were re-engineered by DLR. Additionally, the Airbus A380 as a fastcruising airliner and the subsonic high-end business jet Dassault Falcon 7X were taken for comparison.…”

“…The authors would like to express their gratitude to the Japanese Aerospace Agency (JAXA) and particularly to Atsushi Ueno and Hiroaki Ishikawa for their approval to use the comprehensive and meticulous set of flight performance data of their low-boom supersonic airliner design S4 (iteration 1.3.4, [7]). This was extremely helpful because such a sophisticated and reliable dataset requires multi-disciplinary expertise as well as considerable R&D efforts and thus, is very hard to come by.…”

“…ERA-Interim data, provided by the European Center for Medium-range Weather Forecast (ECMWF) 6. Available at www.usgs.gov/core-science-systems/eros/coastal-changes-and-impacts/gmted2010 7. It turned out that the considered aircraft designs' engine power rarely suffices for altitudes above 51,000 ft, which is the maximum certified flight level for present civilian aircraft, so that a climbing cruise will probably not be allowed.…”

Characterization of topographic effects on sonic boom reflection by resolution of the Euler equations

“…However, due to the sonic boom, overland commercial supersonic flight remains banned in most countries. This has serious consequences on the possible demand for supersonic transport and on its commercial success (Liebhardt et al, 2020). For public acceptance, it is thus important to reduce sonic boom annoyance by designing low-boom aircraft, but also to be able to accurately predict the sonic boom that will be generated at ground level by this new generation of supersonic aircraft.…”