Journal Article
Minimum Trim Drag for a Three-Surface Supersonic Transport Aircraft
S. Seraj, and J. R. R. A. Martins
Journal of Aircraft, 2025
Three-surface configurations offer theoretical drag benefits over two-surface configurations, but the literature is inconclusive on what is the best configuration for a supersonic aircraft. This work uses trim-constrained drag minimization to investigate the impact of different trim surface configurations on supersonic transport design. We first use Reynolds-averaged Navier–Stokes (RANS)-based optimization to compare the trim drag at a supersonic cruise condition for three-surface, canard, and conventional variants of a supersonic transport aircraft. The three-surface configuration has the lowest trim drag at the supersonic condition. We then construct a supersonic buildup model to study the effects of variable trim surface sizing. When the trim surface spans are included as design variables, the design for minimum supersonic drag depends on the desired static margin. Canard configurations are optimal from 0% to 5% static margin, whereas three-surface configurations are optimal from 10% to 25% static margin. We also show that the canard configuration with 5% supersonic static margin is unstable at subsonic conditions. This emphasizes the need to consider subsonic stability and supersonic performance simultaneously for supersonic transport design.