Supersonic Bi-Directional Flying Wing, Part II: Conceptual Design of A High Speed Civil Transport

Abstract

This report designs a supersonic passenger transport using a novel supersonic bi-directional (SBiDir) flying wing (FW) concept that achieves low sonic boom, low wave drag, and high subsonic performance. For supersonic flight, the planform is designed to achieve optimum aspect ratio, span, and sweep angle to minimize wave drag. For subsonic mode, the airplane will be rotated 90° so that the side of the airplane during supersonic flight becomes the front of the airplane. The sweep angle of the LE at subsonic mode is significantly reduced and the aspect ratio is considerably increased by (L/b) 2 where L is the airplane length, and b is the span. This will allow the airplane to have high subsonic performance with short takeoff and landing distance and low stall velocity due to low wing loading. The airfoil suggested is symmetric about the 50% chord location with both sharp leading edge (LE) and sharp trailing edge (TE). The whole 3-D configuration is symmetric about the longitudinal and lateral planes. As the demonstration of concept, the AOA=0° is selected as the low boom design point. A flat pressure surface of the airfoil used as the isentropic compression surface is employed to cancel the downward shock and sonic boom. Diminished take off noise will be achieved by attaining a low stall velocity and mounting the engines on the upper part of the airplane in order to shield the jet noise. A novel LE radial air injection to delay LE stall is suggested to avoid using the conventional LE slats system, which is heavy and complicated. The calculation shows that the 90° rotation can be done in 3 to 5 seconds with a very small centrifugal acceleration. The rotation transitional time will be short enough not to lose lift and the acceleration is so small that no passenger discomfort will be created. This design has the mission requirements of a cruise f Mach 1.6, a range of 2,000 nautical miles, a payload of 70 passengers and a takeoff field length of 2,471 feet. 1 The sonic boom overpressure propagated to ground was found to be 0.3 psf at AOA=0°.

Toward Zero Sonic-Boom and High Efficiency Supersonic Flight, Part I: A Novel Concept of Supersonic Bi-Directional Flying Wing

“…As the proof of concept, the SBiDir flying wing concept is used for a conceptual design of a supersonic civil transport with cruise Mach number of 1.6, payload of 70 passengers, and range of 2500 nautical miles at cruise altitude of 60,000ft [54]. The airfoil used is 3% thickness.…”

Review of Sonic Boom Prediction and Reduction Methods for Next Generation of Supersonic Aircraft

“…Designed by Professor Zha [209] from the University of Miami, the project was picked up by NASA as part of its Innovative Advanced Concepts Selected For Continued Study program. According to the first design stages, analyses and trade studies made by Zha and his research group [210][211][212], the bi-directional flying wing has the potential to revolutionize supersonic flight with virtually zero sonic boom and ultra-high aerodynamic efficiency in both subsonic and supersonic flight phases. The novel planform, shown in Figure 33, is symmetric about both the longitudinal and span axes.…”

“…The time required for the transition between modes can be controlled to be about 5 to 10 s: it appears to be short enough so that from an inertia point of view, neither the momentum nor lift should be affected. Concerning aerodynamic performance and sonic boom, the preliminary CFD simulation [210] for a SBiDir-FW business jet (BJ) at Mach numbers of 1.6 and 2.0 indicates that the configuration generates no N-wave sonic boom on the ground at a high lift-to-pressure drag ratio L/D of 16. The platform adopts a sharp nose and an isentropic compression pressure surface, which minimize the shock wave propagating downward and the resulting sonic boom.…”

Towards High Efficiency Hypersonic Flight-Hypersonic Bi- Directional Flying Wing

“…This paper examines the design of a high efficiency hypersonic vehicles using the bidirectional flying wing concept first employed by Zha 1,2,3,4,5 for use in a supersonic vehicle. This concept successfully allows for many technical challenges involved in supersonic flight to be overcome.…”