However, optimal (A(x)) shifts with (M). The MAC fuselage consists of overlapping, segmented panels reinforced with shape memory alloy (SMA) ribs that contract or expand, altering the radius at each station (x). For hypersonic flight, the nose becomes sharper (lower bluntness ratio) and the midbody swells to reduce wave drag. The wing uses a dual-pivot mechanism embedded in a thermally insulated wing box. Sweep angle (\Lambda) changes via linear actuators, while tilt (\theta_t) changes via rotary joints at the root.
[ C_L = 2\sin^2\theta_p \cdot \cos\Lambda ]
Hypersonic VST-MAC: A Variable-Sweep/Tilt Mach-Area Ruled Configuration for Multi-Regime Flight hypersonic vst mac
[ A(x) = A_\textmax \cdot \frac4xL\left(1 - \fracxL\right)^3/2 ]
| Mach | Fixed fuselage (C_D_w) | MAC fuselage (C_D_w) | % reduction | |------|---------------------------|--------------------------|--------------| | 0.9 | 0.009 | 0.008 | 11% | | 1.2 | 0.045 | 0.027 | 40% | | 2.5 | 0.031 | 0.021 | 32% | | 6.0 | 0.022 | 0.018 | 18% | 4.2 Aerodynamic Efficiency (L/D) The VST wing improves L/D across all regimes. At Mach 0.8, low sweep (20°) and slight anhedral (-5°) give L/D = 14. At Mach 5.0, sweep 75°, dihedral +20° yields L/D = 5.2 — high for a hypersonic vehicle (typical L/D ~ 3-4). The improvement stems from reduced induced drag via spanwise load redistribution at hypersonic speeds. However, optimal (A(x)) shifts with (M)
(conceptual plot): L/D vs. Mach number — VST-MAC outperforms fixed-delta and fixed-sweep designs by 15-40%. 4.3 Thermal-Structural Feasibility The leading edges are C/C-SiC composites with active cooling (endothermic fuel). Fuselage morphing segments use NiTi SMA wires embedded in a high-temperature polymer matrix, rated to 850 K transient. At Mach 6.5 stagnation temperatures reach 2200 K on nose, but the morphing mechanism is located 1.5 m aft of the stagnation line, staying below 700 K. 5. Control and Stability Variable sweep and tilt alter the aerodynamic center (AC). At low speed (Λ=20°, anhedral), AC is at 45% MAC. At hypersonic (Λ=75°, dihedral), AC shifts to 38% MAC. The flight computer uses a gain-scheduled LQR controller, adjusting elevator, canards (deployed only subsonically), and differential wing tilt for roll control.
A. J. Morrow(^1), L. Chen(^2) (^1)Department of Aerospace Engineering, Stanford University (^2)Center for Hypersonics, University of Queensland The wing uses a dual-pivot mechanism embedded in
Hypersonic, Variable Sweep, Area Rule, Morphing Structures, Wave Drag, Multi-Regime Flight 1. Introduction Hypersonic vehicles (Mach > 5) typically sacrifice low-speed performance for high-speed efficiency. Fixed-wing designs suffer from severe wave drag at transonic and supersonic transitions, limiting operational flexibility. Conversely, variable-sweep wings (e.g., B-1, F-14) improve subsonic/supersonic transition but are not designed for hypersonic thermal and pressure loads. Additionally, the classic area rule — which dictates that aircraft cross-sectional area distribution should be smooth to reduce wave drag — is Mach-dependent, yet most airframes are static.
This paper presents the conceptual design and preliminary analysis of the Hypersonic VST-MAC , a novel air-breathing vehicle capable of efficient subsonic, transonic, supersonic, and hypersonic (Mach 6+) flight. The design integrates two enabling technologies: (1) a Variable Sweep/Tilt (VST) wing, which adjusts both sweep angle and anhedral/dihedral tilt to control wave drag and lift distribution, and (2) a Mach-Area Ruled (MAC) fuselage, dynamically deforming via morphing panels to maintain Sears-Haack body equivalence across Mach numbers. Analytical and numerical results indicate a 40% reduction in wave drag at transonic speeds and a 25% improvement in hypersonic lift-to-drag ratio compared to fixed-geometry hypersonic vehicles. The paper details aerodynamic principles, structural mechanics, thermal management, and control strategies.
Lift coefficient in hypersonic regime (Newtonian theory):