Drag Reduction on the Basis of the Area Rule of the Small-Scale Supersonic Flight Experiment Vehicle Being Developed at Muroran Institute of Technology

A small-scale supersonic flight experiment vehicle (OWASHI) is being developed at Muroran Institute of Technology as a flying testbed for verification of innovative technologies for high speed atmospheric flights which are essential to nextgeneration aerospace transportation systems. The second-generation configuration M2011 of the vehicle with a single Air Turbo Ramjet Gas-generator-cycle (ATR-GG) engine has been proposed. Its transonic thrust margin has been predicted to be insufficient, therefore drag reduction in the transonic regime is quite crucial for attainability of supersonic flights. In this study, we propose configuration modifications for drag reduction on the basis of the so-called area rule, and assess their effects through wave drag analysis, wind tunnel tests, and CFD analysis. As a result, the area-rule-based configurations have less drag than the baseline configuration M2011. However, the effects of the proposed bottleneck on the fuselage below the main wing are smaller than predicted. It would be caused by the drag due to separation and shocks around the bottleneck. It is necessary to redesign the area-rule-based bottleneck to be smoother.