Unconventional High Aspect Ratio Joined-Wing Aircraft Incorporating Laminar Flow

Unmanned SensorCraft air vehicles have been proposed as the air-breathing component of a future intelligence, surveillance, and reconnaissance (ISR) infrastructure to provide revolutionary capabilities. Such craft must take advantage of high aspect ratio (AR) wings for aerodynamic efficiency, and may also be required to enclose an antenna in a diamond aircraft planform. A large proportion of fuel must be carried, and loiter is at high altitudes for a few days in each flight. This implies that a wide CL–altitude capability is required. Several types of high AR joined-wing aircraft configurations can be envisaged to meet the possible flight envelope. Previous studies have considered configurations with aft- and forward- swept tips using conventional thick super-critical aerofoil sections. Implications of typical flight envelopes on wing design aspects have been mentioned. This paper extends the design and analysis to explore the use of laminar flow sections. Using panel codes, results are presented here for configurations with simple uncambered wing sections and then for configurations with designed camber and twist, trimmed for neutral stability. The designed wings display a considerable reduction in leading edge suction, yet maintain the lift, drag and near-elliptic wing loading characteristics. Results of an inverse design application are shown here, and further work is proposed in several areas.