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) where L is the airplane length, and b is the span. This will allow the airplane to have high subsonic performance with short take-off 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 take-off field length of 2,471 feet.The sonic boom overpressure propagated to ground was found to be 0.3 psf at AOA=0°. * Undergraduate Student, Dept. of Mechanical and Aerospace Engineering † Graduate Student, Dept of Mechanical and Aerospace Engineering ‡ Associate Professor, Dept. of Mechanical and Aerospace Engineering, Senior AIAA Member 48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition 4 7 January 2010, Orlando, Florida AIAA 2010-1393 Copyright © 2010 by the authors of this paper. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.